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Feeding habits of Beryx splendens and Beryx decadactylus (Berycidae) off the Canary Islands
Abstract
The feeding habits of Beryx splendens and B. decadactylus were determined from stomach contents obtained on a monthly basis during commercial fishing off the Canary Islands in 1996–1997. Changes in diets were studied in relation to predator size and seasonal variation in the food composition. The diet of both species has much in common with regard to its main components of small fishes, crustaceans and cephalopods. More important differences were found in the fish prey of B. decadactylus. A variation in the diet of B. splendens was observed according to its length. Seasonal variations in feeding habits were associated with either variations in the abundance of prey or variations in the depth distribution of predator and prey.
... Platell et al., 1997;Bohórquez-Herrera et al., 2015;Maschette et al., 2020). When available, dietary data for other co-occurring species also highlight whether a species is potentially competing for the same food resources (Edgar and Shaw, 1995;Dürr and González, 2002;Morton et al., 2008;Wuenschel et al., 2014). Dietary data are also relevant to developing plans for managing fisheries resources and their environment (Wuenschel et al., 2014;Bizzarro et al., 2017). ...
... While dietary compositions can sometimes be related directly to prey abundance (e.g. Dürr and González, 2002), they can also act as a broad proxy for the relative abundances of prey when such data are not available (e.g. Hanson and Chouinard, 2002). ...
... Certain berycid species contribute to commercial and/or recreational fisheries in many regions (Dürr and González, 2002;Horn et al., 2010;Nishida et al., 2016;Shotton, 2016). This applies in particular to the widely-distributed Beryx splendens and to a lesser extent Beryx decadactylus, which accounts for dietary studies of the berycid species having focussed largely on Beryx spp. ...
Data for the Berycidae, collected during extensive past scientific surveys, were used to quantify the depth distributions of the four species of Centroberyx and two of Beryx found in Australian coastal waters and thus elucidate the extent to which these species are partitioned by region and depth. The dietary, jaw and dentitional characteristics of the ecologically and fishery-important Centroberyx gerrardi were then determined, providing the first such account for any Centroberyx species. While Centroberyx gerrardi, Centroberyx lineatus, Beryx splendens and Beryx decadactylus are found throughout southern Australia, the last two species extend further up the west and east coasts. Centroberyx australis occurs on the lower half of the west coast eastwards to the central south coast and Centroberyx affinis on the lower half of the east coast. The four Centroberyx species typically occur at depths <350 m and the two Beryx species at > 350 m. On the south coast of Western Australia, depth distributions undergo an overlapping progressive gradation, from C. lineatus in inshore and nearshore shallow waters, to C. gerrardi and C. australis in nearshore deep waters, and then B. splendens and B. decadactylus in offshore deep waters. The main dietary categories of C. gerrardi change with increasing body size from crabs and isopods in small fish to teleosts in the largest fish, in which volumetrically they constituted >60% of the stomach contents. The wide range of teleost prey (at least 39 species from 33 families) ingested by C. gerrardi would be valuable to this species if continuing climate change or other anthropogenic effects lead to alterations in the composition of potential prey. Differences between depth distributions account for the fish prey of C. gerrardi comprising nearshore species, such as those of clupeids, congrids, pomacentrids and platycephalids, whereas those of B. splendens (from studies elsewhere) are dominated by myctophids, which are abundant in deeper waters. The combination of a large mouth and numerous, exclusively small teeth (edentulate morphotype) strongly suggest that C. gerrardi is a suction feeder adapted to engulfing larger prey. While the co-occurring and likewise commercially-fished Oplegnathus woodwardi also ingests substantial volumes of crabs and teleosts, its diet is distinguished from C. gerrardi by large volumes of poriferans and appreciable volumes of echinoderms, likewise reflecting feeding specialisations. Although differing in depth distributions and dietary compositions, berycid species in general are close to the apex of the food web.
... Bien que l"écologie des béryx longs soit relativement bien connue (Masuzawa et al. 1975, Uchida & Tagami 1984, Pshenichny et al. 1986, Dubochkin & Kotlyar 1989, Lehoday 1994, Gomes et al. 1998, Dürr & González 2002, Kakora 2003, 2005, Muto et al. 2005, Vinogradov et al. 2005, les connaissances sur sa génétique et donc sur sa structure populationnelle restent approximatives, ou du moins spatialement assez restreintes, ce qui empêche une gestion maîtrisée et raisonnée de la ressource. Les monts sous-marins, bien que très répandus (Hillier & Watts 2007), constituent un milieu fragmenté (Richer de Forges 1998), ce qui pousserait à penser que la différenciation génétique pourrait être élevée du fait de l"isolement géographique des stocks. ...
... Les premières études sur l"alimentation des B. splendens réalisées par Dubochkin & Kotlyar (1989) abordaient essentiellement un aspect quantitatif. D"autres études du régime alimentaire ont été entreprises, à des échelles plus ou moins locales (Masuzawa et al. 1975, Uchida & Tagami 1984, Pshenichny et al. 1986, Gomes et al. 1998, Dürr & González 2002, Kakora 2003, 2005, Muto et al. 2005, Vinogradov et al. 2005 al. 2010). Globalement, il apparaît que le béryx présente un spectre alimentaire très large. ...
... (Lehodey et al. 1997). Depuis quelques années, plusieurs études ont permis de mieux connaître les caractéristiques biologiques générales de ces espèces, comme le régime alimentaire ou le mode de reproduction (Lehodey & Grandperrin 1996, Adachi et al. 2000, Dürr & González 2002, González et al. 2003, Schönhuth et al. 2005, Horn et al. 2010). Cependant, il reste beaucoup à apprendre avant de pouvoir prétendre à une gestion contrôlée des pêcheries. ...
Le béryx long Beryx splendens est une espèce d'intérêt commercial à distribution circumglobale mais n'est pas encore exploitée en Nouvelle-Calédonie. Les connaissances sur la biologie et la génétique de l'espèce sont susceptibles d'influencer le développement et la gestion de sa pêche. Cependant la structuration et la diversité des populations de béryx sont encore insuffisamment connues. Afin d'étudier ces paramètres de façon approfondie, des marqueurs mitochondriaux et nucléaires ont été utilisés dans le cadre d'une approche comparative. Dans un premier temps et afin de cibler au mieux le marqueur mitochondrial le plus approprié dans cette étude, les séquençages des génomes mitochondriaux complets de l'espèce et de B. mollis ont permis l'estimations du niveau de variabilité génétique intraspécifique, marqueur par marqueur. Des fragments de 815 pb du gène du cytochrome b ont ensuite été séquencés et utilisés pour tenter d'interpréter au mieux l'histoire de l'espèce. Au total, 204 individus issus de 14 populations géographiques naturelles réparties à travers le monde ont été analysés. Les populations de la ZEE de la Nouvelle-Calédonie ont par ailleurs fait l'objet d'une étude particulière. Enfin, les résultats sur l'intensité et la distribution spatiale de la diversité génétique des populations de B. splendens ont été approfondis à l'aide de marqueurs nucléaires. Ainsi, 193 individus, issus des trois océans et incluant une et deux populations de B. decadactylus et B. mollis, respectivement, ont été caractérisés à huit loci microsatellites. Bien que moins contrastés, les résultats obtenus avec ces derniers vont dans le sens de ceux obtenus par l'analyse avec le marqueur mitochondrial. Ainsi, les résultats indiquent une forte diversité génétique chez l'espèce et suggèrent une population globalement en expansion. Une scission de la population de béryx entre l'Atlantique et l'Indo-Pacifique a été mise en évidence. A plus petite échelle, les analyses statistiques n'ont pas mis en évidence de structuration particulière. Nos analyses montrent que l'espèce tendrait à suivre les courants océaniques, suggérant qu'au moins une partie des individus migrent probablement sur de longues distances. Cette étude a permis de détecter un brassage génétique à large échelle océanique, assurant le maintien de la diversité au sein de la population globale de B. splendens.
... It is presumed that individuals have a continual feeding activity and are known to migrate vertically over night for feeding on fish and crustaceans on the slope (Galaktionov, 1985;Dubochkin & Kotlyar, 1989). The diet of B.splendens consists of small meso-or benthopelagic fishes and decapods or species with diurnal vertical migration (Dürr & González, 2002). ...
... Most information about this species is extrapolated from Beryx splendens works because of the similarity between the two species. There is some comparative work on the two species focusing on diet (Dürr & González, 2002) and larval morphology (Mundy, 1990). ...
... Some work exists on the reproduction (Lehodey et al., 1994(Lehodey et al., & 1996Gonzalez et al., 2003), development (Massey & Horn, 1996;Anibal et al., 1998;Rico et al, 2001), distribution (Busakhin, 1982;Ivanin, 1987;Relini et al, 1995) and behavior (Galaktionov, 1984) of B.splendens and its life-history characteristics are normally assumed to be the same for B.decadactylus. No specific studies on B. decadactylus are available, except for some comparative studies with B.splendens on feeding habits (Dürr & González, 2002) and larval stages (Mundy, 1990). ...
MtDNA sequences and microsatellite loci were used as independent molecular markers to reveal the genetic population structure in three deep-sea demersal fish species from the North Atlantic. In the Azores archipelago, the demersal fishery is the second most important after tuna and Helicolenus dactylopterus, Beryx splendens and Beryx decadactylus are among the most captured species.
Partial sequences for the mitochondrial control region and cytochrome b gene were obtained for the three species using universal primers. The diversity encountered for these markers is consistent with diversity found on other marine fishes, except for B.decadactylus in which the d-loop and cyt b diversity was lower than expected.
Haplotype data indicated a strong genetic differentiation between Helicolenus dactylopterus NW, Cape Verde and NE Atlantic populations suggesting long distance colonisation processes by jump dispersal events along major oceanic currents. Eight microsatellite loci were developed for H.dactylopterus in order to resolve population structure at a finer intraregional scale (within Portuguese waters). Significant deviations from allelic frequencies expected under Hardy-Weinberg equilibrium were detected at several loci. Analysis of FIS revealed significant differences from zero as a result of heterozygote deficiency. Estimates of FST, RST and AMOVA were also significant, suggesting that the population structure of this species within Portuguese waters was not homogeneous. Pairwise comparisons of FST, RST and genetic distances (DSW and (s)2) between populations revealed a significant separation of the Azores and Peniche (continental Portugal) populations as well as a moderate differentiation among subpopulations of the Azores archipelago.
Beryx splendens and Beryx decadactylus are two congeneric species with many similarities in known biology. Analysis of haplotype data revealed striking differences in structure and history of the populations of these two species. MtDNA sequences confirmed that Beryx splendens is constituted by one panmitic population within the Northeast Atlantic as has been previously hypothesised by other authors. Surprisingly, indices of genetic diversity were lower in the closely-related B.decadactylus and there was a strong genetic differentiation between Cape Verde and the rest of the NE Atlantic populations when analysed for the same molecular markers. Differences found are discussed based on the limited knowledge of these species especially with respect to lifehistory.
Population structure results are discussed in relation to historical and on-going hydrogeographic events. Evidence for the strong influence of several events previous to the last glacial maximum (LGM) on the population demographic history and evolution of deep-sea demersal fish species in the North Atlantic was found.
... Weight percentage, numerical percentage, the percentage of frequency of occurrence and the index of relative importance, IRI, were also calculated to evaluate the relative importance of each prey item (Cortés 1997;Dürr and González 2002), as follows: ...
... In Lake Ulungur, it was reported that in 1986, before the introduction of Japanese smelt, rotifers accounted for ,6.58% of the total zooplankton (rotifer and crustacean) biomass, whereas cladocerans and copepods dominated total biomass (51.47% and 41.95%, respectively) (Wang and Dou 1998). However, in 2001-2002, several years after the Japanese smelt was introduced into the lake, the biomass structure changed to rotifers (16.67%), cladocerans (39.25%) and copepods (44.08%) (Ye et al. 2004). During our study (November 2006to July 2008, rotifers were dominant, comprising a high proportion of 87.18% of the total zooplankton biomass; cladocerans and copepods comprised 4.05% and 8.78% of the total biomass, respectively (Yang et al. 2011a(Yang et al. , 2011b (Table 6). ...
... Our results also showed that Japanese smelt primarily feeds on rotifers in spring, in terms of N%, and rotifer abundance in this lake was lower in spring during our study period (Yang et al. 2011a(Yang et al. , 2011b, than it was in -2002(Ye et al. 2004, although the overall biomass of rotifers increased. This indicated that rotifer abundance could also be suppressed in spring by the high predation pressure from Japanese smelt. ...
Studies of feeding ecology are essential in gaining an understanding of how established non-indigenous fish species interact with the invaded communities. In the present study, we investigated the composition and seasonal variation in the diet of the introduced Japanese smelt Hypomesus nipponensis, a small planktivorous fish, in Lake Ulungur, China. The objective was to examine the ecological role of this established non-indigenous smelt through the analysis of its diet, which might give more insight into the relationship between its introduction and the collapse of the native Eurasian perch population. Results showed that the Japanese smelt had a broader feeding spectrum than had been previously reported. Of 10 taxonomic or ecological categories of food, cladocerans (54.70%) and rotifers (15.39%) were the most important food items in terms of the index of relative importance (IRI), whereas surface food and chironomid larvae were the most important by weight. Although cladocerans were consistently the most important food, rotifers and copepods, together with surface food and chironomid larvae, substituted when cladocerans were scarcer. Because both rotifers and chironomid larvae are important food of larval and young perch, introduction of Japanese smelt into the lake might be responsible for the collapse of the perch population because of the suppression of rotifers and chironomid larvae in spring through seasonal predation.
... Feeding habits: Feeds on small fishes and several invertebrates (Shimizu 1984;Dürr & González 2002). The splendid alfonsino Beryx splendens is a berycid fish with circumglobal distribution, but does not occur in the Northeast Pacific (Paxton 1999;Golani et al. 2002). ...
... Feeding habits: Feeds on fishes, crustaceans and cephalopods (Dürr & González 2002). Juveniles are found mainly on seagrass beds and adults on rocky reefs (Espino et al. 2015). ...
Studies on life history and stock structure of marine species have evolved in the Azores region during the last 40 years. This information is essential to feed fishery stock assessment models that fit available data to determine current stock status and provide advice on the optimum (sustainable) exploitation. However, most of these data are only available in a fragmented manner in several scientific papers, books, theses and reports. In some cases, these sources of information are difficult to access. The present document aims to gather and summarize biological, ecological and fisheries-related information for the main commercially exploited species in the Azores. The species treated here have previously been selected as priority stocks for assessment and monitoring at regional level by applying a standard framework aligned with the ICES and FAO recommendations. They are: the blackspot seabream Pagellus bogaraveo, veined squid Loligo forbesii, blue jack mackerel Trachurus picturatus, blackbelly rosefish Helicolenus dactylopterus, red porgy Pagrus pagrus, forkbeard Phycis phycis, European conger Conger conger, alfonsino Beryx decadactylus, splendid alfonsino B. splendens, parrotfish Sparisoma cretense, silver scabbardfish Lepidopus caudatus, red scorpionfish Scorpaena scrofa, Atlantic chub mackerel Scomber colias, blacktail comber Serranus atricauda, offshore rockfish Pontinus kuhlii, amberjacks nei Seriola spp., common
mora Mora moro, common spiny lobster Palinurus elephas, black scabbardfish Aphanopus carbo, rough limpet Patella aspera, thornback ray Raja clavata, and Mediterranean slipper lobster Scyllarides latus. The document is presented as concisely and effectively as possible. An overview table of the current data available is presented by stock.
... The closest known reports of the species are from deep waters off Portugal at approximately latitude 40°N, longitude 15°W (Southampton Oceanography Center Discovery Collections Midwater Database, on line). The species has been recently reported from the Canary Islands (Dürr & González, 2002;Wittmann et al., 2004). ...
... However, some specimens have also been reported from examination of stomach contents of bathyal epibenthic/demersal fish, such as deep-sea Beryx spp. (Dürr & González, 2002). ...
The occurrence of the lophogastrid crustacean Lophogaster spinosus is reported for the Gulf of Cadiz waters, in the North-East Atlantic. This constitutes the first report of the species for the Iberian Atlantic region. Samples were collected by demersal trawling during a fisheries research survey performed in March 2008. A total of four specimens were collected at three sampling sites. Depths of occurrence ranged between 363 and 548 m.
... The diet of red bream has been studied in the Canary Islands, where it is a secondary target species in a local fishery for splendid alfonsino (Durr and Gonzalez, 2002). Consistent with the present study, red bream prey on fish, crustaceans, and cephalopods; few prey species could be identified because of the advanced stage of digestion (Durr and Gonzalez, 2002). ...
... The diet of red bream has been studied in the Canary Islands, where it is a secondary target species in a local fishery for splendid alfonsino (Durr and Gonzalez, 2002). Consistent with the present study, red bream prey on fish, crustaceans, and cephalopods; few prey species could be identified because of the advanced stage of digestion (Durr and Gonzalez, 2002). Red bream seem to feed mostly in the water column on mesopelagic fish, pelagic shrimp, and squid. ...
Goldman, S. F. and Sedberry, G. R. 2011. Feeding habits of some demersal fish on the Charleston Bump off the southeastern
United States. – ICES Journal of Marine Science, 68: 390–398.
The feeding habits of several demersal fish on the upper continental slope were investigated to determine the trophic relationships
of these ecologically dominant and commercially important species, and to determine food sources for slope fish off the southeastern
United States. Stomach contents were examined from 534 fish, including wreckfish (Polyprion americanus), barrelfish (Hyperoglyphe perciformis), and red bream (Beryx decadactylus). Fish fed on 46 prey taxa, and there were dietary differences among predators. Wreckfish predominantly consumed teleost
fish and squid; barrelfish had a diet dominated by pelagic tunicates and some mesopelagic fish and squid; red bream consumed
mainly fish, squid, and crustaceans. Seasonal shifts in diet were observed in all three species. Many of the prey items encountered
were vertically migrating organisms, which are a critical link between surface waters and the slope ecosystem.
... These metals can accumulate in different ways in fish organs, posing significant health risks to humans who consume them (Authman et al., 2013; Aiman et al., 2016). Due to its profitability, tilapia production has recently dramatically increased, particularly in Africa (Durr & Gonzalez, 2002). In Egypt, fish play a vital role in the economy, and O. niloticus is one of the ten most important species, contributing to the protein supply-demand balance (Hatem et al., 2013;Mahrou et al., 2022). ...
... The FA profiles of the liver and muscles of B. splendens showed particularly high levels of MUFA, largely owing to the OA content in both tissues. This pattern was largely reflected in the FA profile of the stomach content of B. splendens (i.e., in their diet), which was consistent with adult B. splendens preying on mesopelagic Myctophidae fish that generally possess high levels of MUFA (Dürr et al. 2002;Horn et al. 2010;Saito and Murata 1996). Although the ratios of MUFA/SFA in the tissues were higher than those in the stomach contents, this difference can be explained by the more efficient retention of MUFA in B. splendens tissues than the retention of SFA and/or endogenous production of MUFA from SFA substrates. ...
The splendid alfonsino Beryx splendens is a commercially important deep-sea fish in East Asian countries. Because the wild stock of this species has been declining, there is an urgent need to develop aquaculture systems. In the present study, we investigated the long-chain polyunsaturated fatty acid (LC-PUFA) requirements of B. splendens, which are known as essential dietary components in many carnivorous marine fish species. The fatty acid profiles of the muscles, liver, and stomach contents of B. splendens suggested that it acquires substantial levels of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) from its natural diet. The functional characterization of a fatty acid desaturase (Fads2) and three elongases (Elovl5, Elovl4a, and Elovl4b) from B. splendens confirmed their enzymatic capabilities in LC-PUFA biosynthesis. Fads2 showed Δ6 and Δ8 bifunctional desaturase activities. Elovl5 showed preferential elongase activities toward C18 and C20 PUFA substrates, whereas Elovl4a and Elovl4b showed activities toward various C18–22 substrates. Given that Fads2 showed no Δ5 desaturase activity and no other fads-like sequence was found in the B. splendens genome, EPA and arachidonic acid cannot be synthesized from C18 precursors; hence, they can be categorized as dietary essential fatty acids in B. splendens. EPA can be converted into DHA in B. splendens via the so-called Sprecher pathway. However, given that fads2 is only expressed in the brain, it is unlikely that the capacity of B. splendens to biosynthesize DHA from EPA can fulfill its physiological requirements. These results will be useful to researchers developing B. splendens aquaculture methods.
... Therefore, otoliths of these species are vital for studying piscivorous predators' feeding habits. Furthermore, alleviating the problem of species identification caused by otolith allometric growth provides more accurate feeding studies, which contribute significantly to our understanding of marine food webs, especially at the upper trophic level (Dürr and González, 2002;Garcia-Rodriguez et al., 2011). ...
Species identification by fish otoliths is an effective and appropriate approach. However, the allometric growth of otoliths can cause discrimination confusion, particularly in juvenile otolith classification. In the Southern Ocean, Chionodraco rastrospinosus, Krefftichthys anderssoni, Electrona carlsbergi, and Pleuragramma antarcticum are frequently caught together in krill fishery as bycatch species. Furthermore, the otolith shape of these four species is relatively similar in juvenile fish, making the identification of fish species difficult. In this study, we tried and evaluated many commonly used machine learning techniques to solve this problem. Eventually, by introducing a triplet loss function (function used to reduce intraspecific variation and increase inter-specific variation), the discrimination confusion caused by the allometric growth of otoliths was reduced. The classification results show that the neural network model with the triplet loss function achieves the best classification accuracy of 96%. The proposed method can help improve otolith classification performance, especially under the context of limited sampling effort, which is of great importance for trophic ecology and the study of fish life history.
... In other regions, the diet of alfonsino does not differ and consists mainly of crustaceans and mesopelagic fish. The proportion of fish in the diet composition of alfonsino varies from 11 to 58% depending on the season (Lehodey and Grandperrin, 1996;Durr and Gonzalez, 2002;Horn et al., 2010;Kells and Carpenter, 2011). The features of feeding of species and their habitat affect the composition of erythrocytes and leukocytes of fish, and the ratio of particular cell types can characterize the physiological state. ...
The hematological parameters of the peripheral blood of the Atlantic chub mackerel Scomber colias, bonito Sarda sarda, and splendid alfonsino Beryx splendens are presented based on materials of scientific monitoring on board the fishing vessels in the exclusive economic zones of Morocco and Mauritania in the years 2004-2017. A larger number of immature erythropoietic cells was recorded in the alfonsino, which is probably due to its possible vertical feeding migrations to greater depths with high pressure and low oxygen content. The analysis of erythropoiesis and the leukocyte formula revealed features of physiological and immunological aspects. Bonito has a higher monocyte content than atlantic chub mackerel and alfonsino, which indicates a high level of innate cellular immunity, represented by phagocytosis.
... Most of the classic diversity indices have been used in various studies of cephalopod trophic ecology (e.g. Shannon's diversity, Simpson's dominance, Gini-Simpson, among others), for instance, to describe diet breadth through time and space and among populations (Clark 1985;Ambrose 1986;Dürr and González 2002;Chong et al. 2006;Letelier et al. 2009;Lopez et al. 2009;Bernal et al. 2020). The most common diversity indices, namely the Shannon-Wiener and Gini-Simpson, are based on entropies and lack intuitive interpretation (Jost et al. 2006). ...
Dietary descriptions based on stomach content are pervasive regardless of the biases concerning its methodology, statistics and descriptors. We here review different biases on the stomach content analysis, sample size, and indices used for cephalopods. These mollusks are key components in marine food webs and most are characterized as active predators, thus, knowledge of their feeding ecology based on stomach content analysis is of paramount importance. We suggest alternatives to describe dietary data using unbiased estimators. These are based on re-sampling, using published data of cephalopod stomach content, and conducting estimations using intervals. In our review, we detected that several studies found a high proportion of empty stomachs and highly digested preys, which influences the sample size with contents. In turn, sample size is positively associated with the number of prey species in the stomach contents. Moreover, many studies confuse the terms opportunistic vs. generalist predator and selective vs. specialist predator. Therefore, to improve the understanding of these concepts, we calculated niche-width indices and compared them with prey richness and evenness at individual and population levels. We also show that although most cephalopods exhibit generalized diet and wide trophic niche, their hunting strategy is selective and specialized at individual level. It is worth noting that the diet of over 90% of cephalopod species is not yet known, and thus, the number of trophic studies should increase to fill this gap of knowledge. We provide a series of recommendations to improve and correctly conduct and interpret the studies of stomach content for cephalopods.
Graphical abstract
... They are the prey of organisms living at different depths because they migrate vertically throughout the day. Some predators of G. denudatum are Beryx splendens (Dürr and González, 2002), Chauliodus sloani (Battaglia et al., 2018), Etmopterus spinax (Bengil et al., 2019), Mesoplodon bidens (Pereira et al., 2011) and Todarodes sagittatus (Rosas-Luis et al., 2014). ...
Gonostoma denudatum belonging to Gonostomatidae family are small fishes living in deep-sea around Atlantic and Mediterranean. They are vital species for plastic accumulation because they can be available in all depths of the water column during the day. In this study, it was aimed to present the recent record of G. denudatum, which captured from North Cyprus in May 2018. The total length of the specimen, which obtained from a depth of between 420 and 640 m, is 12.8 cm. Its photograph was taken and the catalogue number (MEUFC-19-11-108) was given. Morphometric characteristics were measured and calculated. The specimen is stored in the Museum of the Systematic, Faculty of Fisheries, Mersin University.
... The occurrence of one crustacean, one fish, and some cephalopods in the stomach is consistent with the preferential diet of the species as reported for populations occurring in the Atlantic Ocean (Dürr and Gonzáles 2002). Prey items similar to those eaten by the fish in the Atlantic Ocean, are available in the deep habitats of the Mediterranean Sea. ...
A new specimen of splendid alfonsino, Beryx splendens Lowe, 1834, was caught by trawling in July 2016 in the Ligurian Sea at the depth of 350 m, in the proximity of a submarine canyon. It represents the 10th documented record of B. splendens in the Mediterranean. Because of the rarity of the records in the basin, there could be doubts whether to consider or not such species as established in the area. However, some findings may support the hypothesis of the possible establishment of the species in the Mediterranean Sea. For example, the stomach of the specimen was nearly full, with rests of one crustacean decapod, one fish, and some cephalopods, which are commonly reported prey items for the species. Macroscopic observation and histological analysis of the gonads revealed that the specimen was a male in an advanced stage of gonadal development. Finally, the coherence of habitat type and prey items with that of extra-Mediterranean populations coupled with gonadal maturation consistent with the observations on other specimens caught in the Mediterranean.
... Role as food organisms. -In marine to freshwater environments, numerous Lophogastrida and Mysida are found in the stomachs of many species of decapods (Lagardère, 1972(Lagardère, , 1977aSiegfried, 1982;Cartes & Abello, 1992;Cartes, 1993a-c) and fish (Sorbe, 1981;Mauchline, 1982;Astthorsson, 1984;Mauchline & Gordon, 1984a, b;Thiel, 1996;Dürr & González, 2002;Wittmann et al., 2004;Specziár, 2005;Specziár & Rezsu, 2009;Carrasco et al., 2012). In certain cases they may play an important role in predator diets. ...
Contents. – Introduction – Outline of the orders – Outline of history – Terminology and definitions. External morphology – Habitus – Size of adults – Carapace – Cephalothorax – Pleon – Telson – Integument and colour – Cephalic appendages – Thoracic appendages – Pleonal appendages. Internal morphology – Musculature – Nervous system – Sensory organs – Digestive system and digestion – Circulatory system – Respiratory system – Reproductive system – Excretory system and excretion – Endocrine organs. Reproduction and sexuality – Sexual dimorphism – Intersexuality – Sex ratio – Mating and oviposition – Fecundity – Incubation – Adjustment of reproductive parameters. Development and moulting – Marsupial development – Moulting and growth – Regeneration – Life cycle. Ecology and ethology – Habitat and distribution – Locomotion, orientation, and taxis – Migration – Social aggregation – Grooming – Food and feeding – Trophic interactions – Symbiotic associations – Parasites. Ecological and economic importance – Contribution to biodiversity – Impact on ecosystems – Importance in fisheries. Phylogeny and biogeography – Fossil record – Phylogeny – Biogeography. Systematics – Guideline on classification – Classification – Keys to the families, subfamilies, and tribes of the Lophogastrida, Stygiomysida, and Mysida. Appendix. Acknowledgements. Bibliography.
... B. splendens was observed to follow actively the migrating prey (Vinnichenko, 1997;Horn et al., 2010), reflected in the present study by its isotope ratios that match those of potential prey organisms like the decapods Acan- thephyra spp. and Sergestes spp. as well as myctophids (Dürr and Gonzalez, 2002). ...
Specific mechanisms, driving trophic interactions within the pelagic community may be highly variable in different seamount systems. This study investigated the trophic structure of zooplankton and micronekton above and around Ampère and Senghor, two shallow seamounts in the subtropical and tropical Eastern Atlantic, and over the adjacent abyssal plains. For the identification of food sources and trophic positions stable isotope ratios (δ¹³C and δ¹⁵N) were used. δ¹³C ranged from -24.7‰ to -15.0‰ and δ¹⁵N covered a total range of 0.9-15.9‰. Based on epipelagic particulate organic matter, zooplankton and micronekton usually occupied the 1st-3rd trophic level, including herbivorous, omnivorous and carnivorous taxa. δ¹³C and δ¹⁵N values were generally lower in zooplankton and micronekton of the subtropical waters as compared to the tropical region, due to the differing nutrient availability and phytoplankton communities. Correlations between δ¹³C and δ¹⁵N values of particulate organic matter, zooplankton, micronekton and benthopelagic fishes suggest a linear food chain based on a single energy source from primary production for Ampère Seamount, but no evidence was found for an autochthonus seamount production as compared to the open ocean reference site. Between Senghor Seamount and the open ocean δ¹³C signatures indicate that hydrodynamic effects at seamounts may modify the energy supply at times, but evidence for a seamount effect on the trophic structure of the pelagic communities was weak, which supports the assumption that seamount communities rely to a large extent on advected food sources.
... Clarke (1964) reported for the first time the capture of two young individuals in the "Canary Islands region". Other records of this species in the archipelago are beaks found in stomach contents of stranded cetaceans (Fernández et al. 2009, Hernández-García & Martín 1994 and slender alfonsino, Beryx splendens Lowe, 1834 (Dürr & González 2002), captured in the area. ...
Two well conserved female specimens of the uncommon soft-scaled squid Lepidoteuthis
grimaldii Joubin, 1895 (Lepidoteuthidae, Oegopsida) were caught in Canary
Island waters: a maturing female of 580 mm dorsal mantle length found dead
on the surface at 27°38'N, 18°01'W (near El Hierro Island); an immature female of
350 mm dorsal mantle length captured by commercial open midwater trawl at
28°48'N, 16°00'W (north of Tenerife Island), between 342 and 487 m depth. This is
the first report of an adult of this species from the Canary Islands. Morphological
data are presented and the bathymetric distribution of this species in Canary waters
is discussed
... B. splendens was observed to follow actively the migrating prey (Vinnichenko, 1997;Horn et al., 2010), reflected in the present study by its isotope ratios that match those of potential prey organisms like the decapods Acanthephyra spp. and Sergestes spp. as well as myctophids (Dürr and Gonzalez, 2002). ...
Specific mechanisms, driving trophic interactions between seamount associated fishes and the pelagic community may be highly variable in different seamount systems. This study investigated the trophic structure and the main prey of benthopelagic fishes from the summit and slope regions of Ampère and Senghor, two shallow seamounts in the subtropical and tropical NE Atlantic, and the adjacent deep-sea plains. For the identification of food sources and nutritional links to the pelagic realm a combination of stomach content and stable isotope ratio (δ¹³C and δ¹⁵N) analyses was used. δ¹³C ranged from −22.2‰ to −15.4‰ and δ¹⁵N covered a total range of 8.0–15.9‰. Feeding types of fish species comprised mainly zooplanktivores and mixed feeders, but also benthivores, piscivores, and predator-scavengers. Based on epipelagic particulate organic matter, they occupied trophic positions between the 2nd and 4th trophic level. Differences in stomach contents and stable isotope signatures indicate a resource partitioning among the benthopelagic fish fauna through distinct habitat choice, vertical feeding positions and prey selection. Topographic trapping of vertically migrating zooplankton on the summit seemed to be of minor importance for food supply of the resident near-bottom fishes, rather horizontal current-driven advection of the planktonic prey was assumed as major factor. Vertically migrating micronekton and mesopelagic fishes show up as key players within the food webs at Ampère and Senghor Seamounts and the adjacent deep-sea plains.
... Transitions between deep-sea and marine habitats in the photic zone are not unusual across the species in this study. For example, Berycidae are primarily slope and shelf dwelling fishes that occupy a range of depths commonly spanning 50-700 m (Dürr and González, 2002), with juveniles often occurring in shallow near-shore waters and even estuaries (Mundy, 1990;Smith, 2000). Transitions between deep-sea and shallow marine habitats are not limited to this clade, and shifts in depth ranges spanning hundreds, if not thousands of meters are observed across numerous lineages in this study. ...
Isolated in one of the most extreme marine environments on Earth, teleost fish diversity in Antarctica’s Southern Ocean is dominated
by one lineage: the notothenioids. Throughout the past century, the long-term persistence of this unique marine fauna has become increasingly threatened by regional atmospheric and, to a lesser extent oceanic, warming. Developing an understanding of how historical temperature shifts have shaped source–sink dynamics for Antarctica’s teleost lineages provides critical insight for predicting future demographic responses to climate change. We use a combination of phylogenetic and biogeographic modelling to show that high-latitude Antarctic nearshore habitats have been an evolutionary sink for notothenioid species diversity. Contrary to expectations from island biogeographic theory, lower latitude regions of the Southern Ocean that include the northern Antarctic Peninsula and peripheral island archipelagos act as source areas to continental diversity. These peripheral areas facilitate both the generation of new species and repeated colonization of nearshore Antarctic continental regions. Our results provide historical context to contemporary trends of global climate change that threaten to invert these evolutionary dynamics.
... Transitions between deep-sea and marine habitats in the photic zone are not unusual across the species in this study. For example, Berycidae are primarily slope and shelf dwelling fishes that occupy a range of depths commonly spanning 50-700 m (Dürr and González, 2002), with juveniles often occurring in shallow near-shore waters and even estuaries (Mundy, 1990;Smith, 2000). Transitions between deep-sea and shallow marine habitats are not limited to this clade, and shifts in depth ranges spanning hundreds, if not thousands of meters are observed across numerous lineages in this study. ...
Percomorph fishes represent over 17,100 species, including several model organisms and species of economic importance. Despite continuous advances in the resolution of the percomorph Tree of Life, resolution of the sister lineage to Percomorpha remains inconsistent but restricted to a small number of candidate lineages. Here we use an anchored hybrid enrichment (AHE) dataset of 132 loci with over 99,000 base pairs to identify the sister lineage of percomorph fishes. Initial analyses of this dataset failed to recover a strongly supported sister clade to Percomorpha, however, scrutiny of the AHE dataset revealed a bias towards high GC content at fast-evolving codon partitions (GC bias). By combining several existing approaches aimed at mitigating the impacts of convergence in GC bias, including RY coding and analyses of amino acids, we consistently recovered a strongly supported clade comprised of Holocentridae (squirrelfishes), Berycidae (Alfonsinos), Melamphaidae (bigscale fishes), Cetomimidae (flabby whalefishes), and Rondeletiidae (redmouth whalefishes) as the sister lineage to Percomorpha. Additionally, implementing phylogenetic informativeness (PI) based metrics as a filtration method yielded this same topology, suggesting PI based approaches will preferentially filter these fast-evolving regions and act in a manner consistent with other phylogenetic approaches aimed at mitigating GC bias. Our results provide a new perspective on a key issue for studies investigating the evolutionary history of more than one quarter of all living species of vertebrates.
... This suggests that the species is more specialized than the snappers (Etelis and Pristipomoides species). B. decadactylus and the rare E. radiatus feed on crustaceans and teleosts, whereas the former species was found to be almost strictly piscivorous in the Canary Islands (Dürr & González 2002). Although B. decadactylus and E. radiatus presented a very high dietary overlap, it is important to note that they did not occupy the same depth layer (E. ...
L'objectif général de cette thèse est d'étudier les relations alimentaires entre différents prédateurs d'intérêt local, appartenant à plusieurs compartiments écologiques. L'échantillonnage, réalisé entre janvier 2012 et décembre 2014 en partenariat avec la filière pêche, s'est concentré sur les principales espèces d'intérêt commercial ou en interactions avec les pêcheries (captures accessoires et déprédateurs). La détermination des sources de matière organique dont elles dépendent, de leurs relations interspécifiques, ainsi que des facteurs de variation de leurs alimentations, a été réalisée grâce à l'analyse des isotopes stables du carbone (δ13C) et de l'azote (δ15N), ainsi que celle des contenus stomacaux. Bien qu'associées au substrat, les espèces profondes (100-600m) dépendent indirectement de la production primaire de surface via leurs proies qui effectuent des migrations verticales dans la colonne d'eau. Cette dépendance aux organismes mésopélagiques induit un chevauchement alimentaire globalement important entre ces espèces, atténué par l'occupation de zones bathymétriques différentes. Concernant les espèces de surface, celles-ci se répartissent selon un gradient côte-large, formant trois groupes aux régimes alimentaires distincts. Les requins tigre semblent former une population homogène constituée d'individus généralistes tandis que les requins bouledogue forment une population hétérogène d'individus spécialisés sur des ressources différentes. Ces résultats indiquent qu'une approche centrée sur l'habitat conviendrait à la gestion des espèces profondes, tandis qu'une approche centrée sur les espèces serait plus efficiente pour les espèces de surface.
... Madeira Archipelago (Wittmann & Wirtz 1998). Azores (Nouvel 1943 (Dürr & González 2002, Wittmann et al. 2004, Hernández et al. 2008, Wittmann & Riera 2012. Off Morocco (De Jong 1996). ...
The zoogeographic distribution of lophogastrid species occurring in the diverse seas of the Iberian Peninsula and neigh-bouring areas is analysed. For each species, data on general distribution, bathymetric ranges, habitat and localities reported on published data are provided. A total of 16 lophogastrids species belonging to 6 genera have been recorded, representing the 30% of all known world extant species and the 67% of genera. Two of them are common to the Atlantic and the Med-iterranean. All known Iberian species are present in the Macaronesian region, 43.8% in the North-western Atlantic and 12.5% in the western Mediterranean. Lophogastrid distributions suggest the existence of an evolution and distribution cen-tre of the group located around the Macaronesian Islands.
... Eigenvalue vector values of major prey items (Thecosomata, Cephalopoda, Decapoda, Fishes, and Porifera) are also plotted Therefore, small and large B. splendens, which we classified here expediently, are probably sub-adult and lower classes, and adult fish, respectively. Previous studies in other waters have been reported that B. splendens prey composition varies according to ontogenetic shift in the demersal zone (Dubochkin and Kotylar 1989; Dürr and Gonzàlez 2002;Horii 2006;Horn et al. 2010). The difference in the %IRIs of plankton and micronekton between large and small B. splendens indicates that intraspecific resource partitioning occurred according to body size-or in other words, ontogenetic shift. ...
We analyzed the stomach contents and nitrogen and carbon stable isotope ratios of three deep-sea fishes Pentaceros wheeleri (North Pacific armorhead), Beryx splendens (splendid alfonsino), and Allocyttus folletti (oxeye oreo)—to elucidate interspecific and intraspecific differences in prey use among demersal fishes in the Emperor Seamount waters (North Pacific Ocean). Principal component analysis using an index of relative importance revealed interspecific differences in prey use: P. wheeleri preyed on plankton and benthos; B. splendens on micronekton and plankton, and A. folletti on micronekton. The relationship between the index of relative importance in B. splendens and body length also indicated ontogenetic shifts in prey use. High percentage of empty stomachs and low stomach fullness index in P. wheeleri indicated this species’ limited feeding ability during its demersal life on seamount. Nitrogen isotope ratio analysis suggested that the trophic level of A. folletti was the highest, followed by large B. splendens, small B. splendens, and P.wheeleri. Variation in carbon isotope ratio values were small, indicating that primary producers were similar. Differences in nitrogen isotope ratio (trophic level) coincided with differences in prey use by the three fishes. Thus, these species are likely able to coexist in seamount waters by partitioning their use of benthos, plankton, and micronekton food resources. They might be supported by food supplied from the surrounding water columns by horizontal flux of plankton or vertical migration of micronekton in the deep scattering layer because except for the benthic prey of P. wheeleri they consumed plankton and micronekton.
... Isidro 1996;Krug et al. 1998;Estácio et al. 2001), and feeding habits in the Azores and Canary Islands (e.g. Gomes et al. 1998;Durr & González 2002). ...
González 2010. Age and growth of the alfonsino Beryx decadactylus (Cuvier, 1829) from the Azores, Madeira and Canary Islands, based on historical data. Arquipelago. Life and Marine Sciences 28: 25-31. Age and growth of the alfonsino Beryx decadactylus from the Azores, Madeira and Canary Islands were studied based on otolith readings. Alfonsino otoliths are thin and show clear annual growth rings. Specimens ranged in size from 21.0 to 50.0 cm fork length (aged 2 to 10 years) in the Azores, 20.0 to 45.0 cm fork length (1 to 11 years) in Madeira, and 21.0 to 44.0 cm fork length (0 to 9 years) in the Canary Islands. No significant differences in growth parameters were found between males and females in any of the three archipelagos. The von Bertalanffy growth parameters for all individuals were: L =68.40 cm L F , k=0.11 year-1 , t 0 =-1.90 year in the Azores; L =70.10 cm L F , k=0.07 year-1 , t 0 =-4.83 year in Ma-deira; L =58.11 cm L F , k=0.11 year-1 , t 0 =-4.70 year in the Canary Islands. No significant differences in growth parameters were found between the three archipelagos.
... Several contributions need to be highlighted here, particularly the impressive studies on European decapods (d'Udekem d'Acoz 1999, Türkay 2001, Iberian decapods (gathering many records from the Canaries, Zariquiey Álvarez 1968), and West African brachyuran crabs (Manning and Holthuis 1981), but also several specific works on brachyurans (Neumann 1996, Fransen and Wirtz 1997, Moro et al. 2014, particularly the accounts on Canarian species of several crab families , 2000, Quiles et al. 2002. Several studies on feeding habits of fishes in waters of the Canaries (Fanlo et al. 1993, 1996, Tuset et al. 1996, Dürr and González 2001, Moreno-López et al. 2002 have also been used as a source of brachyurans occurring in the area. Some projects (DGXIV/C/1 94/034, CAMARON, PESCPROF 1-3, REDECA, AQUACRU, MAR-PROF) have provided us with deep-water crabs from the Canaries, collected with a panoply of fishing gear. ...
Just 20 years have passed since González (1995) finished one of his seminal works on decapod crustaceans of the Canary Islands, thanks to the help of the reputed carcinologists L.B. Holthuis and C.H.J.M. Fransen. This publication allowed d’Udekem d’Acoz (1999) to include the Canarian decapods in his inventory of the NE Atlantic. No checklists of decapod fauna specifically covering this area have been published since then, and an update is needed. The current list of Canarian brachyuran crabs comprises 132 species. Additional species have been recorded thanks to intensified research into deep water, natural range expansions from nearby areas, introduction by anthropogenic activities and description of new taxa; several of these changes are detailed in this review. Although the description of new brachyuran species is not expected to occur at a significant rate, an increase in the number of species from the Canaries is expected to result from trawling and dredging sampling, as well as from introduction of non-native species. For the first time, some zoogeographic comments on the Canarian brachyuran carcinofauna are made. Finally, crab species of commercial interest are listed, their current threats are identified and some updated conservation measures are proposed.
... The analysis of gut content (each single item identified to the lowest taxonomic level possible) revealed 8 undamaged specimens of Sergia robusta (Crustacea, Sergestidae) and the beaks of 10 cephalopods belonging to Histioteuthis sp. The high number of cephalopods remains and mesopelagic decapod crustaceans are in agreement with the observations by Dürr and González (2002) for the eastern-central atlantic. ...
... Gnathophausia zoëa Willemoes-Suhm [66]: 401; [67] [17]; Dürr [15]; Wittmann & Wirtz [73]; Dürr & González [16]; Haroun & Garrido [30]; studied: Canary Islands.-Samples listed in Wittmann et al. [71]. ...
RESUMEN Las aguas que rodean el archipiélago canario constituyen las de mayor riqueza de espe-cies de lofogástridos en el Océano Atlántico, con doce especies meso y batipelágicas de este grupo. Esta diversidad es debida a la elevada intensidad de nuestros conjuntamente con las fa-vorables condiciones marinas. Todas las especies citadas son propias de esta zona, aunque el grado de endemicidad es muy bajo. Diez especies son consideradas cosmopolitas y dos presen-tan una distribución restringida al área Atlántica, encontrándose limitada una de ellas al Atlántico Este. Además, se analizan a nivel biogeográfico las áreas de distribución de las especies canarias de lofogástridos con zonas adyacentes (Macaronesia, Mediterráneo y Costa Atlántica Africana). ABSTRACT The species numbers of lophogastrids in open waters off E. Atlantic islands (Azores, Madeira, Canaries, and Cape Verdes) exceed those in waters off N.W. African continental coasts and in the Mediterranean Sea. With twelve currently known, mainly meso-to bathy-pelagic species, the waters off the Canary Islands appear to be the most species-rich in the Atlantic Ocean. This comparatively large number may reflect high sampling intensity in combination with favourable environmental conditions. All the here documented species appear to be indigenous, but the degree of endemism is very low: ten Canarian species are cos-mopolitans, two are endemic to the Atlantic, only one of the latter two is restricted to the E. Atlantic. Biogeographical data are provided for the lophogastrids from the Canary Islands and surrounding areas (Macaronesian region, Mediterranean and Atlantic African coasts).
... Some of the smaller species eaten (such as Brachioteuthis and the myctophids) may have represented secondary prey items. Symbolophorus barnardi (Tåning, 1932) and Diaphus metopoclampus (Cocco, 1829), for instance, have been recorded in the diet of Beryx from the Canary Islands (Dürr & González, 2002), while myctophids have been recorded as a prey item for Hoplostethus (Bulman & Koslow, 1992). ...
Shepherd's beaked whale Tasmacetus shepherdi is one of the most poorly known cetaceans, whose diet has created some speculation given that its dentition differs greatly from that of most other beaked whales that are primarily teuthophagous. The few stomachs examined previously have given seemingly conflicting dietary information. In this paper the stomach contents of a freshly stranded adult female on Tristan da Cunha have been examined through identification of trace elements and genetic analysis of soft parts. At least 13 cephalopod and 8 fish species were identified from beaks and otoliths respectively, but only undigested fish remains were present in the stomach and identified genetically as Beryx splendens. Reconstituted masses totaled 8809 g for cephalopods and 17,554 g for fish, with four species (Histioteuthis atlantica, Taningia danae, Ommastrephes bartrami and Pholidoteuthis 'A') comprising 78.6% of the cephalopods and one species (B. splendens) comprising 87.4% of the fish eaten. It is concluded that Tasmacetus may alternately exploit fish and cephalopods, depending on the time of day and access to seamount or continental slope areas.
... The decrease of B. splendens at Condor follows a period of high catches, between 2000 and2002 (Figs. 3 and4), by the larger longline vessels, which resulted in a pronounced decline in landings in subsequent years. B. decadactylus has similar morphological and biological characteristics as its congener B. splendens, and the two species are often sympatric (Busakhin, 1982;Dürr and Gonzalez, 2002;Isidro, 1996). Although life history data for this species are sparse, studies on age and growth conducted in the eastern and western North Atlantic show that it is a longer lived, slow growing species, and therefore highly vulnerable to overfishing Friess and Sedberry, 2010;Krug et al., 2011). ...
... Beryx splendens is also the main target species of smallscale fisheries in some regions such as the Canary Islands or Japan (Anon 1995;Akimoto et al. 2002). Some studies made in recent years have helped to improve our understanding of the general biological features of the species, such as reproductive or feeding habits (Lehodey and Granperrin 1996;Adachi et al. 2000;Dürr and González 2002;Gonzalez et al. 2003). Without genetics data, however, an important part of the necessary information is still lacking, precluding controlled fisheries management. ...
La presente tesis utiliza la modelización con “Ecopath with Ecosim” (EwE) como herramienta para describir el funcionamiento de los ecosistemas marinos costeros, incluyendo la pesca artesanal de la isla de El Hierro. Esta modelización se realiza con el objetivo de tener una aproximación al ecosistema litoral de la Isla y evaluar los efectos que tuvo la erupción submarina de 2011 en las comunidades litorales y en la pesca artesanal. Gracias a esta modelización se dibujan unos escenarios actuales y futuros con las tendencias en biomasas de los componentes de las comunidades litorales, los recursos pesqueros y el esfuerzo pesquero. Estos escenarios son útiles para evaluar las dinámicas de recuperación de las comunidades y los recursos pesqueros frente al evento catastrófico que supuso la erupción submarina y generan unas propuestas útiles para el manejo y gestión de los espacios naturales y los recursos pesqueros de la Isla.
Cephalopods are a diverse group of species, with a high ecological and economic relevance. Despite this, its species diversity has been studied in few places at regional scale. We herein aim to update the current state of knowledge and diversity of cephalopods fauna of the Canary Islands. We carried out a systematic review of the available literature regarding cephalopod species in the area spanned from 1834 to 2019. More specifically, we reviewed (a) records of historic and recent research cruises; (b) records of species from scientific literature and technical reports; and (c) stomach contents analysis of top predators. A total of 48 documents, including scientific literature, technical reports, and species referenced in museums collections of cephalopods caught around the Canary Islands were identified. The current species richness in different habitats from coastal to deep-sea zones was determined according to records and previous information on the ecology of each species. These records revealed that this small archipelago holds 85 confirmed species belonging to 31 families, representing ca. 10% of the overall known cephalopod diversity. The cephalopod community was dominated by oceanic cephalopods, followed by shelf-slope and coastal cephalopods species with 65, 11, and 9 species, respectively. 47% of the species showed a wide geographic distribution (33 cosmopolitan and 7 presents in more than one ocean), whereas 19 are only encountered in the Atlantic Ocean and Mediterranean Sea and 26 are exclusively Atlantic. This species richness is comparable to other cephalopod biodiversity hotspots, such as the Indian Ocean Ridge or the Caribbean. The Canarian cephalopod diversity likely to be underestimated, since scarce information exists on species inhabiting the deeper water layers around the Canary Islands. This work represents the first baseline of cephalopod biodiversity around the Canary Islands; hence, it constitutes a first step to develop future research on this taxonomic group.
The present study was carried out in the Tigris river south of Baghdad for the period from July 2016 to April 2017. During which 169 fish were harvested. Oreochromis niloticus Nile tilapia ranged from 68 to 274 mm in length and total weights from 6.6 to 378.79 g. Water temperatures ranged between 31 and 8.5c. With values of pH ranges from 7.2 and 7.8. The values of dissolved oxygen ranged from 11.5g-1 to 7.1g-1 and salinity values were recorded from 0.82g-1 to 0.44g-1. The physic-chemical properties were suitable for the growth and living of Nile tilapia in the Tigris River. The relationship between total length and weight was found to be allometric 2.039. The growth criteria values were k 0.108 and t o 0.27. Maximum expected length L ∞ of fish reaches 293.68 mm. The average condition factor was 2.67. Six age groups were identified and recorded the highest increase in length during the first year of the fish's life and by 34.10%.
Information used for the predator-prey relationships for the JFRE.
The functional group codes correspond to the codes used to identify the functional groups these codes come from S1 Table.
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The present study was carried out in the Tigris river south of Baghdad for the period from July 2016 to April 2017. During which 169 fish were harvested. Ranged total from 68 to 274 mm in length and total weights from 6.6 to 378.79 g. Water temperatures ranged between 31 and 8.5˚c.With values of pH ranges from 7.2 and 7.8. The values of dissolved oxygen ranged from 11.5g-1 to 7.1g-1 and salinity values were recorded from 0.82ppt to 0.44ppt. The physic-chemical properties were suitable for the growth and living of Nile tilapia in the Tigris River. The relationship between total length and weight was found to be Allometric 2.039. The growth criteria values were k 0.10 (yr) and to 0.27 (yr). Maximum expected length L∞ of fish reaches 293.68 mm. The average condition factor was 2.67. Six age groups were identified and recorded the highest increase in length during the first year of the fish's life and by 34.10
جمعت عينات أسماك البلطي النيلي Oreochromis niloticus والأزرق Oreochromis aureus خلال ألمدة من تموز 2016 إلى حزيران 2017 من نهر دجلة جنوبي بغداد بواقع عينة كل شهر استخدمت شباك النصب Gill nets ذات فتحات 20 و30 ملم، جمعت 218 سمكة بلطي نيلي بأطوال كلية تراوحت بين 68 الى 279 ملم، وأوزان كلية بين 6.6 الى 379.68 غم ، و236 سمكة بلطي أزرق وبأطوال كلية بين 35 الى 279 ملم وذات اوزان كلية بين 11.6 الى 387.79 غم. تراوحت درجة حرارة المياه من 8.5 الى 31م˚ ودرجة حرارة الهواء بين 9.2 - 35.1م˚، وسجلت قيم الأس الهيدروجيني فكانت بين 7.2 و 8.2 ، أما قيم الاوكسجين الذائب والمتطلب الحيوي للأ وكسجين، فتراوحت بين 7.1 الى 11.5 ملغم/لتر و1.2 الى 4.4 ملغم/لتر على التوالي . سجلت ادني قيم للتوصيلية الكهربائية وبلغت 690 مايكروسيمنز/ سم خلال شهر نيسان 2016 وأعلى قيمة 1290 مايكروسيمنز/سم بلغت خلال شهر كانون الثاني 2017. تراوحت قيم الملوحة بين 0.44 الى 0.82 جزء بالألف ، فيما تراوحت قيم المواد الصلية الذائبة من 345 الى 645 ملغم/لتر . سجلت ادنى قيمة للعكارة 10.53 واعلى قيمة 235 نفلومترية . بلغت قيمة b (2.01) لعلاقة الطول الكلي بالوزن الكلي وهذا يشير إلى أن نمو سمكة البلطي النيلي ليس قياسيا". وكانت قيمة b 1.76 لعلاقة الطول الكلي مع الوزن الكلي لسمكة البلطي الازرق والتي تظهر نموا ليس قياسيا". بلغ معدل معامل الحال لسمكة البلطي النيلي خلال مدة الدراسة 1.96 . ولسمكة البلطي الأزرق 1.98 واظهر قيما" متباينة اعتمادا" على مديات الطول المختلفة . وجد أن سمكة البلطي النيلي تصل إلى العمر السادس لكلا الجنسين . وسجلت أكبر زيادة سنوية في الطول خلال السنة الأولى وبلغت 89.49 ملم وبنسبة 40.02% ، فيما وصلت سمكة البلطي الأزرق االعمر السابع ، وسجلت أكبر زيادة سنوية في الطول خلال السنة الأولى من عمرها إذ كانت 82.56 ملم وبنسبة 37.00% تصل أسماك البلطي النيلي إلى أقصى طول متوقع في نهر دجلة 293.68\ ملم فيما بلغت قيمة k 0.10 سنة و to -0.19 سنة . أّما سمكة البلطي الأزرق فأن اقصى طول متوقع 293.68 ملم وبلغت قيمة k 0.26 سنة و to 0.01- سنة تراوحت مديات الخصوبة المطلقة لسمكة البلطي النيلي بين 372 الى 3553 بيضة الخصوبة النسبية بمعدل 10.12 بيضة/غم من وزن السمكة. أمّا في سمكة البلطي الأزرق فتراوحت مديات الخصوبة المطلقة بين 528 الى 2654 بيضة والخصوبة النسبية 9.46 بيضة/ غم من وزن السمكة. ووجد أن سمكة البلطي النيلي تعتمد في غذائها بشكل رئيس على المواد العضوية إذ شكلت 61.79% ، فيما شكلت النسبة الأعلى من غذاء سمكة البلطي الأزرق وبلغت 46.34% وسجل نشاط تغذية عالي لجميع فصول السنة لنوعي الأسماك.
ABSTACT
Fish samples of Nile tilapia Oreochromis niloticus and blue tilapia were collected during the period from July 2016 to June 2017 from the Tigris River south of Baghdad. A sample of each month was collected by gill nets of mesh size 20 and 30 mm. A total of 218 Nile tilapia with total lengths ranged from 68 to 279 mm and total weights from 6.6 to 379.68 g, 236 blue tilapia with total lengths ranged from 35 to 279 mm and total weights from 11.6 to 387.79 g. The physical and chemical properties of water were measured. The temperature ranged from 8.5 - 31 ° C and the air temperature between 9.2 - 35.1 ° C. The pH values were ranged from 7.2 to 8.2. The values of dissolved oxygen and Biological Oxygen Demand ranged from 7.1 to 11.5 mg / L and 1.2 to 4.4 mg /L, respectively. The lowest value for conductivity were 690 μm / cm during April 2016 and 1290 μm / cm during January 2017. Salinity ranged from 0.44 to 0.82 g/L, While soluble values ranged from 345 to 645 mg /L. The lowest value of turbidity while high was 235 NTU. The values of b from relationships between total length and total weight of Nile and blue Tilapia were 2.01 and 1.76 respectively that indicating the growth was Allometric. The condition factor rate of Nile tilapia was 1.96, In the blue tilapia it was 1.98 and the condition factor showed "mixed" values at different lengths. The Nile tilapia was reach the sixth age of both sexes. The largest annual increase in length during the first year was 89.49 mm and 40.02%. The blue tilapia reached to the seventh year with the largest annual increase in length during the first year which was 82.56 mm and 37.00%. L∞ of Nile tilapia 293.68 mm while the value of k 0.10 years and t0 -0.19 years. Blue tilapia was 293.68 mm while k 0.26 years and t0 -0.01 years. The absolute fecundite was 372 to 3553 eggs and the relative fecundity was 10.12 eggs / g Weight of the fish. In blue tilapia the absolute fecundity ranges ranged from 528 to 2654 eggs and relative fecundity from 9.46 eggs / g of fish weight. The Nile tilapia was found dependon organic matericls accounting for 61.79%, while accouting in blue tilapia 46.34%. The two fish recorded high feeding activity for all seasons of the both species of fish.
أجريت هذه الدراسة في نهر دجلة جنوبي بغداد للفترة من تموز 2016 الى حزيران 2017. تم خلالها صيد 236 سمكة البلطي الأزرق بأستخدام وسائل الصيد ألمختلفة ( الشباك والكرف والنصب) . وبأطوال كلية تراوحت من 35 الى 279 ملم وذات اوزان كلية من 11.6 الى 387.79 غم . بلغت درجة حرارة الماء من 8.5 الى 31˚C ودرجة حرارة الهواء بين 9.2- 35.1C ودرجة ألأس الهيدروجيني بين 7.2- 8.2 وكانت ملائمة لنمو ومعيشة ألأسماك في نهر دجلة . سجلت اكبر زيادة سنوية في الطول خلال السنة الاولى من عمر سمكة البلطي الازرق اذ كانت 82.56 ملم وبنسبة 37.00% وهي لا تخضع لضاهرة لي لانها كانت متذبذبة بين الصعود والهبوط . وانها تعيش حتى السنة السابعة من عمرها ووتتناقص أعدادها مع التقدم بألعمر . وجدت العلاقة بين الطول الكلي والوزن الكلي حيث بلغت قيمة b (1.76) وهي غير متماثلة وتشير الزيادة بالنمو لصالح مكعب الطول على حساب الوزن . بلغت قيم معايير النمو k وto 0.06 و yr) )-0.18 على التوالي واقصى طول متوقع L∞ كان 293.68 ملم . كانت قيمة معامل الحال 1.79 وهي تشير الى الحالة الصحية والتغذوية ألجيدة للأسماك
أجريت هذه الدراسة في نهر دجلة جنوبي بغداد للفترة من تموز 2016 الى حزيران 2017. تم خلالها صيد 236 سمكة البلطي الأزرق بأستخدام وسائل الصيد ألمختلفة ( الشباك والكرف والنصب) . وبأطوال كلية تراوحت من 35 الى 279 ملم وذات اوزان كلية من 11.6 الى 387.79 غم . بلغت درجة حرارة الماء من 8.5 الى 31˚C ودرجة حرارة الهواء بين 9.2- 35.1C ودرجة ألأس الهيدروجيني بين 7.2- 8.2 وكانت ملائمة لنمو ومعيشة ألأسماك في نهر دجلة . سجلت اكبر زيادة سنوية في الطول خلال السنة الاولى من عمر سمكة البلطي الازرق اذ كانت 82.56 ملم وبنسبة 37.00% وهي لا تخضع لضاهرة لي لانها كانت متذبذبة بين الصعود والهبوط . وانها تعيش حتى السنة السابعة من عمرها ووتتناقص أعدادها مع التقدم بألعمر . وجدت العلاقة بين الطول الكلي والوزن الكلي حيث بلغت قيمة b (1.76) وهي غير متماثلة وتشير الزيادة بالنمو لصالح مكعب الطول على حساب الوزن . بلغت قيم معايير النمو k وto 0.06 و yr) )-0.18 على التوالي واقصى طول متوقع L∞ كان 293.68 ملم . كانت قيمة معامل الحال 1.79 وهي تشير الى الحالة الصحية والتغذوية ألجيدة للأسماك
The present study was carried out in the Tigris river south of Baghdad for the period from July 2016 to April 2017. During which 169 fish were harvested. Oreochromis niloticus Nile tilapia ranged from 68 to 274 mm in length and total weights from 6.6 to 378.79 g. Water temperatures ranged between 31 and 8.5c. With values of pH ranges from 7.2 and 7.8. The values of dissolved oxygen ranged from 11.5g-1 to 7.1g-1 and salinity values were recorded from 0.82g-1 to 0.44g-1. The physic-chemical properties were suitable for the growth and living of Nile tilapia in the Tigris River. The relationship between total length and weight was found to be allometric 2.039. The growth criteria values were k 0.108 and t o 0.27. Maximum expected length L ∞ of fish reaches 293.68 mm. The average condition factor was 2.67. Six age groups were identified and recorded the highest increase in length during the first year of the fish's life and by 34.10%.
The present study was carried out in the Tigris river south of Baghdad for the period from July 2016 to April 2017. During which 169 fish were harvested. Oreochromis niloticus Nile tilapia ranged from 68 to 274 mm in length and total weights from 6.6 to 378.79 g. Water temperatures ranged between 31 and 8.5c. With values of pH ranges from 7.2 and 7.8. The values of dissolved oxygen ranged from 11.5g-1 to 7.1g-1 and salinity values were recorded from 0.82g-1 to 0.44g-1. The physic-chemical properties were suitable for the growth and living of Nile tilapia in the Tigris River. The relationship between total length and weight was found to be allometric 2.039. The growth criteria values were k 0.108 and t o 0.27. Maximum expected length L ∞ of fish reaches 293.68 mm. The average condition factor was 2.67. Six age groups were identified and recorded the highest increase in length during the first year of the fish's life and by 34.10%.
A comparative study of food and feeding habits of two fish species, Chrysichthys nigrodigitatus (Lacepede) and Brycinus nurse (Ruppel) was carried out in the Ethiope, a tropical river. Fish species were procured from fishermen, using cast-nets, fish traps, hooks and lines for fish catch. Specimens were chilled with ice-blocks in a heat-insulated cooler and transported to the laboratory at the University of Benin for analysis. One hundred fish specimens were examined and their stomach contents analysed. Two methods were applied for the analysis, namely, the frequency of occurrence method and the volumetric method. The result of the analysis showed that C. nigrodigitatus was an omnivorous detritivore, while B. nurse was a herbivore. Thus, they occupied different ecological niches and hence were found in abundance in the same water body.
Fish stocks associated with seamounts may be particularly susceptible to overexploitation. From January to July 2001, the Spanish Oceanographic Institute (IEO) conducted an experimental fishing survey entitled ‘Palguinea-2001’ on the seamounts of the Sierra Leone Rise. Beryx splendens (commonly called alfonsino) is the main commercial demersal fish associated with this area. The aim of this study was to investigate the effects of a demersal longline fishery targeting B. splendens on the previously unexploited small Machucambo Seamount over a short time-scale, and also to consider trends in pooled catch rate at another four seamounts. During 110 fishing days at Machucambo, a total catch of 207 tonnes of B. splendens was taken with a fishing effort of 1 309 070 hooks. A spectral analysis and red-noise spectra procedure (REDFIT) algorithm was used to identify the red-noise spectrum from the gaps in the observed time-series of catch per unit effort by weight. Our results show the potential impact of longline fishing pressure on an unexploited ecosystem – after approximately 50 fishing days, the stock appeared to decline substantially, as reflected by a marked drop in catch per unit effort. The apparent rapid decline of the stock might be related to the small size and the virgin state of the Sierra Leone seamounts. The results could be extrapolated to similar small seamounts elsewhere.
In 1941, Fage (1941), referring to the shape of carapace, antennal scale, epimeral plates of sixth abdominal somite and structure of maxilliped, proposed three groups of species in the genus Gnathophausia, but did not give these groups taxonomical status. On the basis of new comparative morphological analysis, a valid genus is established for each group, and thus the family Gnathophausiidae now includes three genera: Fagegnathophausia gen. nov., Gnathophausia Willemoes-Suhm, 1873 and Neognathophausia Petryashov, 1992. Fagegnathophausia gen. nov. differs from the other two genera by sharply serrated median dorsal keel of carapace, presence of dorsal spiniferous ridge by the rostrum base, longer basal segment of maxillula endopod, which is three times as long as distal segment, wider oval distal segment of maxillula endopod, presence of large spatulate exopod on maxilliped, differentiated pereopodal dactyli, which are cone-shaped on pereopods 2–3 and stylet-shaped on pereopods 4–8, presence of spines on the inner margin of uropodal sympodite and crown shaped apex of telson.
A mass-balance trophic model was built in order to describe the impact of the different fleets that operate in the Gran Canaria marine ecosystem between 2005 and 2010. This is the first food-web model developed in the Canary Islands, and results were presented and compared with other ecosystems that have been modeled in Atlantic and Mediterranean coastal areas. Thirty-four functional groups were defined, corresponding to benthic, demersal, and pelagic domains, also including the deep scattering layer (DSL) and detritus. Keystone index and mixed trophic impacts matrix showed a bottom-up control in the benthic-demersal area while in the pelagic zone intermediate predators such as cephalopods, are more relevant to the ecosystem. Primary production required to sustain the fishery was higher when taking into account the detritus and the primary producers, suggesting the importance of detritivorous organisms such as crustaceans, DSL, molluscs, and other benthic species in the catches. Recreational fishermen exert high impacts on most groups of the ecosystem, especially in breams and epidemersal fishes. Benthic sharks, groupers, breams, parrotfishes, leatherjacket fishes, and common pandora showed high exploitation rates, suggesting that these species are overexploited.
The present study provides fisheries biology knowledge which will allow the implementation of regulatory measures contributing to the sustainability of the fisheries and the conservation of the stout beardfish Polymixia nobilis Lowe, 1838 off the Canary Islands, north eastern Atlantic Ocean. Males ranged between 16.5 and 38.4 cm fork length (FL) and females from 14.2 to 46.5 cm FL. Sex ratio by size classes provided significant differences in classes higher than 36 cm, being clearly unbalanced in favour of females. Individuals in maturing and mature stages were present during all months sampled, although a spawning peak is evident between April and June. Size at first maturity was estimated as 26 cm FL for females and 30 cm FL for males. Age was determined from annuli in whole otoliths. Age range was found to be 0–14 years for fish measuring 14.2 to 46.5 cm FL. It is a slow-growing and long-lived species. Significant differences in the growth parameters between sexes were detected. The von Bertalanffy growth parameters estimated for females (n = 213) were L ¥ = 45.92 cm LF, k = 0.16 years)1 and t 0 =)2.84 years; and for males (n = 186) L ¥ = 36.44 cm LF, k = 0.26 years)1 and t 0 =)2.16 years. Stomach analysis indicated some variations in the feeding habits with growth: individuals of small and medium sizes preyed on crustaceans and fishes, while large specimens preyed mainly on fishes.
2 Abstract: This paper provides information on the diets of Oreochromis niloticus and Sarotherodon galilaeus in Ero reservoir. Fish species were procured from fishermen every fortnight using gill nets, cast nets, traps, hooks and lines. Specimens were chilled with iced blocks at the point of collection and transported to th e laboratory. 494 fish specimens were examined and their stomach contents analyzed. Frequency of occurrence and numerical methods were employed in this study. The result of the analysis showed that O. niloticus and S. galilaeus fed on similar food items. These were mainly macrophytes, Chlamydomonas species and Spirogyra. Other food items include detritus, sand grains and insect parts. Thus both species are omnivorous and occupy the same ecological niche.
We examined the diet of nearly 7500 orange roughy Hoplostethus atlanticus Collett, 1889 from southeastern Australian waters caught during trawl surveys in 1988 and 1989. Juveniles f ed mainly on bentho- and meso-pelagic Crustaceans, while mature fish consumed predominantly fish and squid. The composition of the diet changed significantly with depth, geographical area, and year. Evidence of diel feeding periodicity found in adults at a station sampled over 42 h was supported by patterns of stomach fullness and digestion stage in the full data set. Based upon observed rates of stomach evacuation, daily rates of food consumption were estimated as 1.15 % body weight for adults and 0.91 % for juveniles. The metabolism of orange roughy, estimated from a mass balance model, is similar to that of active, migratory mesopelagic fishes and substantially higher than that of non-migratory bathypelagic fishes. The bodily composition of orange roughy, which is high in lipid and protein and low in water, is also similar to that of active mesopelagic fishes. Non-migratory bathypelagic fishes typically have exceptionally low metabolic rates, which, despite low food consumption, lead to high growth rates and high growth efficiency. Orange roughy, however, appears to have very high metabolic costs, which lead to an exceptionally low growth rate and growth efficiency, despite relatively high rates of food consumption.
Diets of 15 species of demersal and pelagic fishes on the upper continental slope (420 to 550 m) were determined, based on samples taken every two months over 13 mo (April 1984 to April 1985) off eastern Tasmania. The calorific contribution of each prey item to the diets was determined. The fish could be divided into four trophic categories: pelagic piscivores, epibenthic piscivores, epibenthic invertebrate feeders and benthopelagic omnivores. Dietary overlap between the groups was low. The pelagic piscivores Apogonops anomalus, Trachurus declivis, Brama brama, Lepidopus caudatus and Macruronus novaezelandiae primarily consume the shelf-break myctophid Lampanyctodes hectoris; their diet is narrow, with a large overlap between species. The epibenthic piscivores Deania calcea and Genypterus blacodes both take a greater variety of prey, but have little dietary overlap. The fish feeding on epibenthic invertebrates, Coelorinchus sp. 2 and Centriscops humerosus, obtain most of their energy from benthic Crustacea and Ophiuroidea, supplemented with Lampanyctodes hectoris; the diet is broad, with little overlap. Among the benthopelagic omnivores (Cyttus traversi, Coelorinchus sp. 4, Lepidorhynchus denticulatus, Neocyttus rhomboidalis, Helicolenus percoides, Epigonus denticulatus and E. lenimen), most diets are broad and show slight overlap. All but E. denticulatus consume significant quantities of Lampanyctodes hectoris as well as Crustacea, particularly Polychaeta, Euphausiacea and Pyrosoma atlanticum. Seasonal changes in diet occurred in G. blacodes, T. declivis, Lepidopus caudatus, Coelorinchus sp. 4, Lepidorhynchus denticulatus, H. percoides, E. denticulatus and E. lenimen; these were related to changes in abundance of particular prey species, not to alterations in feeding habits. Only three species, Lepidopus caudatus, Coelorinchus sp. 2 and H. percoides, showed significant diel feeding periodicity. Ontogenetic dietary changes were evident in Cyttus traversi, Coelorinchus sp. 2, Lepidorhynchus denticulatus and H. percoides. Cyttus traversi and H. percoides progressively changed from crustaceans to fish as their size increased. The diets of size classes within species showed little overlap, except for Lepidorhynchus denticulatus, which eats chiefly euphausiids and Lampanyctodes hectoris at all sizes. In addition to describing the diets and trophic relationships of 90% of the fish biomass, the results emphasize the importance to the entire fish community of mesopelagic food resources, particularly Lampanyctodes hectoris. Many benthopelagic species undertake extensive vertical migrations in search of prey, thus playing a major role in the transport of energy from midwater regions to the benthos of the continental slope.
Intraspecific virtual dietary breadth, degree of diet similarity, dietary overlap and feeding strategies of the silver barb Puntius gonionotus and the tilapia Oreochromis spp. were estimated in a pond from Bangladesh and compared using various niche indices. Appropriateness, ease of interpretation and explanation of different indices were evaluated. Dietary breadths were relatively higher in small sizes of P. gonionotus than large ones, though neither size class could be considered as a generalist feeder. There was a significant dietary overlap between large and small barbs. Niche breadths were similar for both sizes of Oreochromis spp., a little higher for the small sizes, although as with the barbs, neither size class could be considered as a generalistic feeder. Dietary overlap of large tilapia on small ones was much greater but significant in both ways. Czekanowskis' Proportional Similarity (PS) index reveals a much broader aspect of the ecological determinants of niche breadth as it incorporates resource availability and resource use and has got the ease of biological interpretation. Similarly, Levins' dietary overlap indices reveal clearly both the significance, strength and direction of dietary overlap between competitors. According to the PS index, both species are opportunistic feeders, although tilapias are relatively more generalist than the silver barbs. Evidence of significant dietary overlap between the large and small sizes of both species reflects strong competition and indicates caution for mixed-size stocking of tilapia in pond polyculture. Feeding pattern of silver barb reflected a mixed strategy with a combination of both high between- and within-phenotype contributions to the niche width, but with the between-phenotype contribution as the largest. While tilapias reflected high within-phenotype contributions to the niche width, a generalized feeding strategy showed a trend of specialization of a population for periphytic food.
Sympatric native Anolis species with similar structural habitats but contrasting climatic habitats are closer in head and body size on species-rich than on depauperate islands. In two localities, sympatric Anolis species with differential occurrences in sun or shade sought lower, more shaded perches during midday, resulting in partly nonsynchronous utilization of the vegetation by the two species. The second observation may be related to the first in the following way: nonsynchronous spatial overlap could dictate relatively great resource overlap for species coinhabiting patchy or edge areas, requiring great differences between the species in prey size in addition to those in climatic habitat. The extent of such overlap on small depauperate islands could be greater if these contained a greater proportion of patchy or edge habitats (with respect to insolation), or if climatic preferences were broader and more overlapping than on large, species-rich islands. In each locality, the relatively more shade-inhabiting species occurred more often on larger perches and on lower perches than did the other species. In both species of the Bermudan pair, adult males occupied higher and larger perches, and in grahami, shadier perches, than did female-sized individuals. The statistical significance of these and other differences was evaluated using several unweighted @g^2 procedures, Cochran's weighted @g^2 test and a partitioning technique for analyzing interactions among variables in complex contingency tables. The last method is described in detail in the papaer by Fienberg, immediately following this one.
Methods for analysing fish stomach contents are listed and critically assessed with a view to their suitability for determining dietary importance—this term is defined. Difficulties in the application of these methods are discussed and, where appropriate, alternative approaches proposed. Modifications which have practical value are also considered. The necessity of linking measurements of dietary importance to stomach capacity is emphasized and the effects of differential digestion upon interpretation of stomach contents outlined. The best measure of dietary importance is proposed as one where both the amount and bulk of a food category are recorded.
Age and growth of the alfonsino Beryx splendens off the Canary Islands, Madeira and the Azores were studied based on otoliths readings. Otoliths are thin and show clear annual growth rings. Fish aged 1–9 years (18.2–38.9 cm fork length (FL)) were found in the Canary Islands, 0–12 years (15.2–41.0 cm FL) in Madeira, and 0–11 years (15.3–43.0 cm FL) in the Azores. No significant differences in the growth parameters were found between males and females. The von Bertalanffy growth parameters for all individuals were: L∞=44.51 cm FL, k=0.15 per year, and t0=−3.41 years in the Canary Islands; L∞=58.71 cm FL, k=0.06 per year, and t0=−5.71 years in Madeira; and L∞=43.10 cm FL, k=0.17 per year, and t0=−2.80 years in the Azores. Individuals grow fast during the first year of life, attaining approximately 50% of their maximum length; after the first year, the annual growth rate drops rapidly.
Some 17 species of berycomorphid and percomorphid teleost fish occurred in pelagic and demersal samples taken in the Rockall
Trough during the period 1973 to 1981. Demersal trawls were deployed at approximately 250 m bathymetric intervals between
400 and 2900 m depth. Pelagic rectangular midwater trawls were fished open to depths of approximately 2500 m. The most common
species caught were Hoplostethus atlanticus, a subdominant among the species caught in the 1000 to 1250 m bathymetric zones, and Epigonus telescopus and Aphanopus carbo, subdominants among the species caught in the 500 to 750 m zones. The majority of the other species were rare in the samples.
Hoplostethus atlanticus and Epigonus telescopus, whose distributions do not overlap bathymetrically, both exploit the benthopelagic fauna. Aphanopus carbo prey primarily on other fish. The exploiters of the epibenthos are Beryx decadactylus, Lycodes spp., Cataetyx laticeps, and Spectrunculus grandis. The rare Nesiarchus nasutus may exploit benthopelagic prey while the remaining eight species are primarily meso- and bathypelagic. Three of them, however,
also exploit benthopelagic prey to varying degrees; they are Scopelogadus beanii, Poromitra crassiceps, and possibly Melanostigma atlanticum.
Fishes and zooplankton were obtained (March–April 1979 and partly in August 1974) from 45 hauls taken during the day and at night in the central equatorial Atlantic between Latitude 3°N and 2°S from the surface to 1250-m depth, using the RMT 1+8, a combined opening-closing plankton and micronekton trawl. The vertical distribution of 30 myctophid species is described. All species migrate in a diel pattern, Ceratoscopelus warmingii and Lampanyctus photonotus down to at least 1250 m. During daytime most species aggregated at 400-to 700-m depth, therefore only partly occupying the depth of the Deep Scattering Layer (400 to 500 m at 15 kHz). The feeding patterns of seven of the most abundant species were compared, with a total of 1 905 stomach contents being analysed. All seven species are regarded as opportunistic predators, which feed predominantly during the night on calanoid copepods. A total of 66 species of calanoid copepods were identified among the prey items, with smaller species definitely being in the minority. Stomachs of C. warmingii (700 to 1 250 m depth) and Lepidophanes guentheri (500 to 900 m depth) from daytime samples contained copepod species restricted to the upper 150 m of the water column, including Undinula vulgaris, Nannocalanus minor, and Euchaeta marina, thereby confirming an extended vertical migration of predators. Differences in diet and preferences between species in their total food spectrum are described.
The larval development of the alfonsins, Beryx spp., is described from specimens collected from the central North Pacific Ocean (29°N, 179°E) during July 1984, primarily in the upper 50 m. Yolk-sac larvae, 1.5-3.0 mm standard length (SL), have pigment at the forebrain and midbrain, the anterior end of the oil globule, over the intestine above the anus, and around the tip of the notochord. Pelvic buds form at 1.5-3.0 mm SL; flexion occurs between 3.7 and 6.0 mm SL. Fin ray formation is complete and scales are formed by 15 mm SL. Characters useful for identifying Beryx larvae include very elongate, early forming pelvic rays and anterior dorsal spines; a slightly S-shaped intestine about half the standard length; and sparse pigment restricted to internal pigment at the gas bladder, over the posterior intestine, and a spot located asymmetrically on the forebrain. Spines on the first lower infraorbital, characteristic of adult Beryx, develop at 3.8-4.5 mm SL. Juvenile B. splendens and B. decadactylus, from the North Atlantic, differ from each other in dorsal fin ray count.
Using daily catch data on the rose prawn (Aristeus antennatus) an attempt was made to construct a model relating catch per unit effort (CPUE) and a luminosity factor proportional to luminosity levels at the bottom on the prawn fishing grounds. A close relationship between this luminosity factor (defined in the text) and catchability was observed. Daily catch rates were highest during the 2 h immediately after sunrise, associated with a certain optimum light threshold. Within this pattern catch rates varied with longitude according to season and trawling depth. Based on these findings, novel alternatives for the future management of this resource are presented.
The feeding habits of John Dory (Zeus
faber) were studied, based on the analysis of stomach contents from fish sampled in five groundfish surveys. These surveys were carried out off the Portuguese coast during different seasons between 1990 and 1992. The main aspects of feeding biology analysed in this paper are: ontogenetic diet changes, temporal variations in food composition and feeding intensity. Multivariate methods were used to investigate ontogenetic diet shifts. Two main length groups were identified: 8.0–24.9 cm fish, feeding mainly on dragonets and silvery pout, and 25.0–55.9 cm fish whose diet was mainly composed of blue whiting and snipefish. A transitional phase (24.0–30.9 cm fish) with a mixed food composition was observed. This ontogenetic diet shift does not seem to correspond to any important change in body morphology but it does coincide with the onset of sexual maturity in the species.
The specific composition and abundance of bathyal decapods in the Catalan Sea were investigated. A total of 109 bottom trawls were effected at depths ranging from 141 to 730 m on the continental slope in the Catalan Sea (northwestern Mediterranean) during two sampling cruises in spring and autumn 1991. Multivariate analysis of the samples revealed four groups of the decapod crustacean communities: (1) A shelf-slope transition-zone group at depths between 146 and 296 m, primarily characterized by the presence of Plesionika heterocarpus; (2) an upper-slope community between 245 and 485 m, characterized by the presence of the mesopelagic species Pasiphaea sivado and Sergestes arcticus, with Processa nouveli, Solenocera membranacea and Nephrops norvegicus as secondary species; (3) a middle-slope community below 514 m, with Aristeus antennatus and Calocaris macandreae as the most abundant species; (4) a group at 430 to 515 m, comprising all samples collected exclusively within or in the vicinity of submarine canyons. Mesopelagic decapods were predominant on the slope, while benthopelagic fishes (Merluccius merluccius, Micromesistius poutassou, Gadiculus argenteus) replaced mesopelagic decapods on the shelf. There were seasonal variations, with higher densities of mesopelagic species in spring, which were probably related, among other factors, to variations in the photoperiod. Our surveys also revealed higher species richness in the canyons together with seasonal changes in the megafaunal biomass. Generally, the upper and middle-slope communities both displayed seasonal changes in the composition and abundance of megabenthos.
Seven years of simultaneous, quasi-continuous data collected by the Nimbus-7 Coastal Zone Color Scanner and by a deep-ocean sediment trap in the Sargasso Sea allow the derivation of empirical relationships between remotely sensed ocean color and the sinking of particulate carbon into the deep sea. In agreement with earlier observations, the results indicate a 1.5-month lag between surface-ocean events observed by the satellite and arrival of a record of those events, carried by sinking particles, at a depth of 3200 m. In addition, the results suggest that the sea-surface area most influential on particle-flux characteristics recorded by the sediment trap in the Sargasso Sea lies to the northeast of the trap's mooring site. The results point towards possible ways of quantifying the role of marine biota in the regulation of atmospheric carbon dioxide through use of satellite observations.
Berycidae Fiches FAO d'Identi®cation des Espe Áces Pour les Besoins de la Pe Ãche Age and growth of the alfonsino Beryx splendens Lowe. 1834 from the Macaronesian archipelagos Development and present status of Japanese trawl ®sheries in the vicinity of seamounts
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Annual and diel light cycle as a predictive factor in deep-water ®sheries of the prawn Aristeus antennatus (Risso, 1816) On the study of age of alfoncino (Beryx splendens Lowe) of the thalassobathyal zone of southeastern Atlantic Polar Marine Fisheries and Oceanography Research Institute
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Reproductive cycles of fish in the study of species structure and the functional structure of the habitat
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Diet and food consumption of a deep-sea ®sh, orange roughy Hoplostethus atlanticus (Pisces: Trachichthyidae) off southeastern Australia Deep-water decapod crustacean communities in the Northwest Mediterra-nean: in¯uence of submarine canyons and season
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Especies de interés pesquero de Canarias. Gobierno de Canarias. Consejerı́a de Pesca y Transportes
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On the study of age of alfoncino (Beryx splendens Lowe) of the thalassobathyal zone of southeastern Atlantic
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splendens Lowe) of the thalassobathyal zone of southeastern
Atlantic. In: Methods of Determining Age and Growth of New
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Oceanography Research Institute, Murmansk, 1980. Abstr.
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Islas Canarias. Publicaciones Turquesa, Santa Cruz de Tenerife,
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Biology and abundance of alfonsino and bluenose off the lower east coast North Island
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®sheries in the vicinity of seamounts. In: Uchida, R.N., Hayasi,
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W.B. (Eds.), Fiches FAO d'Identi®cation des Espe Áces Pour les
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