Figure 1 - uploaded by Ryo Kawabe
Content may be subject to copyright.
Map of the study site in the Tsugaru Strait, Japan. The lower panel shows the northern part of Honshu and southern part of Hokkaido, Japan. Adult Japanese flounder were caught and released with DT loggers at the point marked by the white star. Numbers indicate flounder identification number and identify the particular fish recovery location (note numbers on both panels). SFCS indicates the location of Shiriuchi Fisheries Cooperative Society. The dashed lines show 10, 20, 30, 40, 50, 70, 100, 200 and 300 m contours.
Source publication
Analysis of high-frequency depth-recording data of adult Japanese flounder Paralichthys olivaceus (Temminck & Schlegel) with depth/temperature logging tags, released in the Tsugaru Strait of northern Japan, has yielded new insights into behavioural differences on vertical movement. Here, we document diel differences in fine-temporal-scale swimming...
Contexts in source publication
Context 1
... Mann–Whitney U -test and Wilcoxon signed rank test. Comparisons of the parameters between day and night were also made using the Mann–Whitney U -test. The significance level was set as 1⁄4 0.05. Eleven fish were released with a DT logger, and eight were recaptured by commercial fishermen, up to 225 days after release. A summary of the dates of release and recapture, fish weights and record duration is provided in Table 1. Six individuals (Flounder #3, #4, #5, #7, #8 and #9) were recaptured off the coast of Shiriuchi within 10 km of the release point, while the other two individuals (Flounder #1 and #2) were caught along the coast of northern Honshu Island and had travelled 56 and 105 km, respectively, from their release points (i.e. across the Tsugaru Strait; Figure 1). The data presented comprise 102.1 days of flounder behaviour. Unfortunately, two DT loggers failed (Flounder #1 and #9), therefore only six sets of data are reported here. There were no significant differences in body size between recovered and unrecovered fish before release (Mann–Whitney U -test, p 4 0.05). Table 2 summarizes the data on the number of swimming events, the height off the seabed, event duration, ascent and descent rate, swimming activity and ambient water temperature. Figure 3 shows time-series depth data from six flounder in Kikonai Bay. Vertical movement of tagged fish was characterized by periodic departures from the seabed, a short period of swimming in the water column, and then returning to the seabed. However, fish tended to remain on the seabed for over 90% of the recording period. Frequently, we observed a repetitive pattern of an ascent followed by a descent (i.e. swimming up and down), before returning to the seabed (Figure 4). Vertical movements included one (Figure 4a) or more (Figure 4b) distinct ascent and descent phases. Depth profiles with multiple peaks were observed when fish ascended more than 2.5 m. Overall, vertical excursions consisting of one peak were more frequent than multi-peak excursions (71.5% vs . 28.5% of the excursions, respectively). Mean swimming duration ranged from 44 Æ 49 to 94 Æ 164 s and the longest duration was 2670 s (44.5 min, Flounder #5). The distribution of swimming duration was heavily skewed to short periods, suggesting that the majority of the time ( 4 80%) in their swimming duration was 5 100 s (Figure 5). Similarly, the distribution of swimming height off the seabed was heavily skewed, suggesting that for most of the time ( 4 75%), flounder in this study made the most of their vertical excursions within 2 m from seabed (Figure 6). There was a significant difference (Wilcoxon signed rank test, p 5 0.0001) between the ascent and descent rates, where the mean ascent rate was 11.3 Æ 5.4 to 16.3 Æ 9.9 cm s À 1 and the mean descent rate was 6.1 Æ 3.2 to 8.8 Æ 6.2 cm s À 1 , suggesting that flounder adopted a swim-and-glide movement pattern. Fish experienced water temperature ranging from 14.8 Æ 1.9 to 16.6 Æ 0.2 ...
Context 2
... flounder appear in the northern part of Honshu Island (Tsugaru Strait) of Japan and spawn from May to June, and concentrate on feeding during September–November (i.e. no-spawning season) (Minami 1997). These movements have been studied using conventional tagging methods (reviewed in Minami 1997). However, variations in fish behaviour, which may cause changes in catchability, are not easily detected in conventional tagging data. The objective of this article is to examine diel differences in the swimming behaviour of Japanese flounder in the Tsugaru Strait and their effect on catchability. In this study, we used shorter- sampling-interval depth data (3 s) from six adult flounder equipped with a depth- and-temperature logger (DT logger), which provided a useful opportunity to observe continuous records of vertical movement for durations of up to 25 days. We also varied the sampling frequencies, from 3 to 120 s, to determine how sampling intervals effect the quality of the behavioural parameters (i.e. swimming duration and height off seabed) obtained. The field experiments were conducted in Kikonai Bay on the southern coast of Hokkaido, in the Tsugaru Strait, Japan (41 38 0 N, 140 28 0 E; Figure 1). The bay is relatively shallow (10–50 m depth), and has a flat bottom. Bottom substrate in the study site is mainly fine sand with some patches of fine gravel nearshore. Kikonai Bay is characterized by a simple bottom topography, with depth mainly ranging from 10 m (close to the coast) to 100 m (offshore). In most places the bottom has a gradual southeastward decline (Figure 1). As a result of this bottom topography, movement of flounder along the bottom is likely to involve a change in depth that can be recorded by the electronic depth/temperature logger attached to the flounder. We used 11 adult P. olivaceus for the tagging experiments. All fish, which were caught using trap nets and hook and line by local commercial fishermen in the Kikonai Bay, were transferred to the Shiriuchi Fisheries Cooperative Society (SFCS) located on the coast of Kikonai Bay (Figure 1), where they were kept in a circular flow-through holding tank (5 m diameter, 0.5 m depth) with a constant supply of aerated seawater. They were tagged 1–3 days later. The water temperature in the tank was maintained at ambient ocean temperature (approximately 14 C) and natural light cycles were simulated. Wounded, sluggish or apparently lifeless fish were not tagged. The size of adults in southern Hokkaido and northern Honshu- Island is known to be greater than 40 cm (total length) for females and 35 cm for males (Minami 1997). Thus, in order to determine the vertical movements of adult P. olivaceus we selected fish in good condition and were greater than 40 cm in total length. As adult P. olivaceus is completely piscivorous regardless of the size (age) and sex (Minami 1997), these tagged fish were used to estimate vertical movement patterns in relation to foraging. The selected 11 fish were anesthetized by briefly submerging them in well- oxygenated seawater containing 0.3 mL L À 1 of 2-phenoxyethanol. After measuring the body weight and length of the fish, we attached a data logger to the anterior dorsal part of the fish body with a plastic string which was passed through two tiny holes (0.5 mm diameter) and secured to 2 cm rubber discs on the ventral surface. The fish were kept for at least 24 h in the holding tank to allow recovery after ...
Context 3
... flounder appear in the northern part of Honshu Island (Tsugaru Strait) of Japan and spawn from May to June, and concentrate on feeding during September–November (i.e. no-spawning season) (Minami 1997). These movements have been studied using conventional tagging methods (reviewed in Minami 1997). However, variations in fish behaviour, which may cause changes in catchability, are not easily detected in conventional tagging data. The objective of this article is to examine diel differences in the swimming behaviour of Japanese flounder in the Tsugaru Strait and their effect on catchability. In this study, we used shorter- sampling-interval depth data (3 s) from six adult flounder equipped with a depth- and-temperature logger (DT logger), which provided a useful opportunity to observe continuous records of vertical movement for durations of up to 25 days. We also varied the sampling frequencies, from 3 to 120 s, to determine how sampling intervals effect the quality of the behavioural parameters (i.e. swimming duration and height off seabed) obtained. The field experiments were conducted in Kikonai Bay on the southern coast of Hokkaido, in the Tsugaru Strait, Japan (41 38 0 N, 140 28 0 E; Figure 1). The bay is relatively shallow (10–50 m depth), and has a flat bottom. Bottom substrate in the study site is mainly fine sand with some patches of fine gravel nearshore. Kikonai Bay is characterized by a simple bottom topography, with depth mainly ranging from 10 m (close to the coast) to 100 m (offshore). In most places the bottom has a gradual southeastward decline (Figure 1). As a result of this bottom topography, movement of flounder along the bottom is likely to involve a change in depth that can be recorded by the electronic depth/temperature logger attached to the flounder. We used 11 adult P. olivaceus for the tagging experiments. All fish, which were caught using trap nets and hook and line by local commercial fishermen in the Kikonai Bay, were transferred to the Shiriuchi Fisheries Cooperative Society (SFCS) located on the coast of Kikonai Bay (Figure 1), where they were kept in a circular flow-through holding tank (5 m diameter, 0.5 m depth) with a constant supply of aerated seawater. They were tagged 1–3 days later. The water temperature in the tank was maintained at ambient ocean temperature (approximately 14 C) and natural light cycles were simulated. Wounded, sluggish or apparently lifeless fish were not tagged. The size of adults in southern Hokkaido and northern Honshu- Island is known to be greater than 40 cm (total length) for females and 35 cm for males (Minami 1997). Thus, in order to determine the vertical movements of adult P. olivaceus we selected fish in good condition and were greater than 40 cm in total length. As adult P. olivaceus is completely piscivorous regardless of the size (age) and sex (Minami 1997), these tagged fish were used to estimate vertical movement patterns in relation to foraging. The selected 11 fish were anesthetized by briefly submerging them in well- oxygenated seawater containing 0.3 mL L À 1 of 2-phenoxyethanol. After measuring the body weight and length of the fish, we attached a data logger to the anterior dorsal part of the fish body with a plastic string which was passed through two tiny holes (0.5 mm diameter) and secured to 2 cm rubber discs on the ventral surface. The fish were kept for at least 24 h in the holding tank to allow recovery after ...
Context 4
... flounder appear in the northern part of Honshu Island (Tsugaru Strait) of Japan and spawn from May to June, and concentrate on feeding during September–November (i.e. no-spawning season) (Minami 1997). These movements have been studied using conventional tagging methods (reviewed in Minami 1997). However, variations in fish behaviour, which may cause changes in catchability, are not easily detected in conventional tagging data. The objective of this article is to examine diel differences in the swimming behaviour of Japanese flounder in the Tsugaru Strait and their effect on catchability. In this study, we used shorter- sampling-interval depth data (3 s) from six adult flounder equipped with a depth- and-temperature logger (DT logger), which provided a useful opportunity to observe continuous records of vertical movement for durations of up to 25 days. We also varied the sampling frequencies, from 3 to 120 s, to determine how sampling intervals effect the quality of the behavioural parameters (i.e. swimming duration and height off seabed) obtained. The field experiments were conducted in Kikonai Bay on the southern coast of Hokkaido, in the Tsugaru Strait, Japan (41 38 0 N, 140 28 0 E; Figure 1). The bay is relatively shallow (10–50 m depth), and has a flat bottom. Bottom substrate in the study site is mainly fine sand with some patches of fine gravel nearshore. Kikonai Bay is characterized by a simple bottom topography, with depth mainly ranging from 10 m (close to the coast) to 100 m (offshore). In most places the bottom has a gradual southeastward decline (Figure 1). As a result of this bottom topography, movement of flounder along the bottom is likely to involve a change in depth that can be recorded by the electronic depth/temperature logger attached to the flounder. We used 11 adult P. olivaceus for the tagging experiments. All fish, which were caught using trap nets and hook and line by local commercial fishermen in the Kikonai Bay, were transferred to the Shiriuchi Fisheries Cooperative Society (SFCS) located on the coast of Kikonai Bay (Figure 1), where they were kept in a circular flow-through holding tank (5 m diameter, 0.5 m depth) with a constant supply of aerated seawater. They were tagged 1–3 days later. The water temperature in the tank was maintained at ambient ocean temperature (approximately 14 C) and natural light cycles were simulated. Wounded, sluggish or apparently lifeless fish were not tagged. The size of adults in southern Hokkaido and northern Honshu- Island is known to be greater than 40 cm (total length) for females and 35 cm for males (Minami 1997). Thus, in order to determine the vertical movements of adult P. olivaceus we selected fish in good condition and were greater than 40 cm in total length. As adult P. olivaceus is completely piscivorous regardless of the size (age) and sex (Minami 1997), these tagged fish were used to estimate vertical movement patterns in relation to foraging. The selected 11 fish were anesthetized by briefly submerging them in well- oxygenated seawater containing 0.3 mL L À 1 of 2-phenoxyethanol. After measuring the body weight and length of the fish, we attached a data logger to the anterior dorsal part of the fish body with a plastic string which was passed through two tiny holes (0.5 mm diameter) and secured to 2 cm rubber discs on the ventral surface. The fish were kept for at least 24 h in the holding tank to allow recovery after ...
Similar publications
Underwater video recordings in the mouth of a squid trawl were used to evaluate the effectiveness of a trawl configured with
drop-chain groundgear to catch longfin inshore squid (Doryteuthis pealeii) and reduce bycatch of finfish in the Nantucket Sound squid fishery off Cape Cod, Massachusetts, USA. Entrance through the
trawl mouth or escape undern...
A total of 1926 flounder (Platichthys flesus luscus Pallas, 1811) were caught monthly by bottom trawl in the south -eastern Black Sea from August 1995 to August 1996. Length-weight relationships, age, growth, mortality, condition factor, gonadosomatic index and sex ratio of the samples were investigated. Individuals were composed of 43 (2.23 %) juv...
The evaluation of the daily ration and feeding periodicity in a Mediterranean demersal fish assemblage under natural conditions is presented. Data were obtained during four trawl surveys conducted on the shelf-edge of the central Mediterranean Sea. Recently, researchers have begun to consider this area an essential fish habitat due to its extremely...
The bathymetry of Baffin Bay with shallow sills both to the north and south creates a relatively isolated body of deep polar water, unique among the Arctic Seas. During 105 trawl hauls completed during autumn 2004, 45 fish species were collected in the northern Baffin Bay between 72o 02' N - 76o 55' N, depth 150-1 418 m. As a first step the abundan...
Citations
... It should be noted that gillnets are usually set over night. Visual predators, including pleuronectid and paralichthyid flatfishes, remain on the bottom and forage food usually traveling small distances during the day (Olla et al., 1972;Tsuruta and Omori, 1976;Gibson et al., 2015), but they swim more actively during the night than during the day (Miyazaki et al., 1997;Solmundsson et al., 2003;Kawabe et al., 2009). Marbled flounder and its congeneric winter flounder spawn eggs during the night (Sato, 1971;Stoner et al., 1999), although the spawning behaviour of Japanese flounder as suggested by data loggers was mainly observed during the day (Yasuda et al., 2013). ...
The present study aims to clarify the Seasonal bathymetric distributions of three coastal flatfishes (stone flounder, marbled flounder, and Japanese flounder) that are caught mainly by bottom trawls and gillnets off the coast of Fukushima, Japan, by using logbook data. All three species were found to have specific spawning depths, i.e., depths of 40–80 m, 20–40 m, and 10–60 m for stone, marbled, and Japanese flounders, respectively, with extremely high catch-per-unit-effort during their spawning seasons, reflecting spawning ground formation. Furthermore, Japanese flounder showed a tendency to expand their distribution offshore to depths deeper than 100 m after October. These results indicate interspecific variations in migration and aggregation patterns. Using logbook data and considering the seasonal catchability of each fishing gear enabled us to understand the seasonal bathymetric distribution of each species and the depths of their spawning grounds.
... However, greater swimming endurance is associated with migratory capacity (Taylor & McPhail, 1986), maintenance of position in flowing water (Blake, 2004;Peake, McKinley, & Scruton, 2005), and greater success in prolonged cruising pursuit of prey (Rice & Hale, 2010), not to mention improved escapement from fishing trawls (Winger, He, & Walsh, 1999). While primarily demersal, some flatfishes do spend time engaged in prolonged above-benthos swimming, particularly at night (Hunter, Metcalfe, O'Brien, Arnold, & Reynolds, 2004;Kawabe et al., 2009;Walsh & Morgan, 2004). Adult P. stellatus migrate from nearshore spawning grounds to deeper waters on the continental shelf annually (Orcutt, 1950), although it is unknown if longer migrations occur. ...
• Phenotypic polymorphisms often differ in multiple correlated traits including morphology, behavior, and physiology, all of which can affect performance. How selection acts on these suites of traits can be complex and difficult to discern. Starry flounder (Platichthys stellatus) is a pleuronectid flatfish that exhibits rare polymorphism for the direction of eye migration and resulting whole‐body asymmetry. P. stellatus asymmetry morphs differ subtly in several anatomical traits, foraging behavior, and stable isotope signatures, suggesting they may be ecologically segregated, yet performance and metabolic differences are unknown.
• Here we tested the hypothesis that sinistral and dextral P. stellatus asymmetry morphs diverge in performance and routine metabolic rate (RMR) by comparing prolonged swimming endurance (time to exhaustion at a constant swimming speed), fast‐start swimming velocity and acceleration, and rate of oxygen consumption. Based on subtle morphological differences in caudal tail size, we expected sinistral P. stellatus to have superior prolonged swimming endurance relative to dextral fish, but inferior fast‐start performance.
• Sinistral P. stellatus exhibited both significantly greater prolonged swimming performance and fast‐start swimming performance. However, sinistral P. stellatus also exhibited greater RMR, suggesting that their general swimming performance could be enhanced by an elevated metabolic rate.
• Divergence between P. stellatus asymmetry morphs in swimming performance and metabolic rates contributes to growing evidence of ecological segregation between them, as well as our understanding of possible ecological consequences of asymmetry direction in flatfishes. These data provide an example of the complexity of polymorphisms associated with multiple correlated traits in a rare case of asymmetry polymorphism in a marine flatfish species.
... The travel time to the laboratories was an hour and a half by car. The tagging and release procedures for flatfish such as Japanese flounder, Paralichthys olivaceus, have been previously described (Kawabe et al., 2004(Kawabe et al., , 2009Yasuda et al., 2010Yasuda et al., , 2013. In brief, we carefully selected specimens that were not injured. ...
The reproductive performance of barfin flounder (Verasper moseri), a multi-batch spawner spawning during February-April (boreal winter) in the wild, is particularly sensitive to temperature perturbations. Final oocyte maturation (FOM) of captive flounder occurred only when post-vitellogenesis fish experienced a slowly-elevated water temperature regime (SETR) (from 2. °C to 6. °C over a month). We used electronic tags to show how post-vitellogenesis flounder experience SETR during its pre-spawning migration, during their southward migration, to a location about 750. km from the summer feeding grounds in the coastal waters of Hokkaido (CWH; 40.2-43.4°N). From 2010 through 2012, we tagged a total of 208 . V. moseri in early December at the feeding grounds of the CWH, during in which vitellogenin incorporation into oocyte was almost completed. One hundred and two tags were recovered and the data from 98 were downloaded. All of the tagged females moved offshore by the end of January. Fish spent more time in cold and deeper waters (3-4. °C, 351-380. m) in January than they did in December (6-8. °C, 33-59. m), but experienced warmer temperatures (5.1-5.7. °C, 367-396. m) in February and March around the spawning period. All tagged fish experienced SETR and then experienced the onset of SETR in January, although SETR of tagged fish have large variations among individuals. A comparison between depth-temperature data recorded by data-logger and oceanic horizontal temperature conditions suggests that fish did not experience warm surface water of the Tsugaru Warm Current, a branch of the Kuroshio that flows into the Pacific Ocean via the Tsugaru Strait, and instead were in the colder Oyashio water by migrating deep and finally experiencing warmer water in February and March. In conclusion, SETR appears to be one of the exogenous factors that induces FOM in the wild.
... Hunter et al., 2004Hunter et al., , 2009Solmundsson et al., 2003) if the registration frequency is sufficiently high (cf. Kawabe et al., 2009). Previous flatfish studies using electronic tags focused on recording tracks over broad spatial scales and describing the general pattern of movements (e.g. ...
... In the analysis, the time resolution was unified at 20 s by using only every second registration of the 10 s data series. A high sampling frequency compared to previous tagging studies of marine fishes was chosen as previous studies suggested that low sampling frequencies would lead to inaccuracies in the number of identified events and the statistics of various components (see Kawabe et al., 2009). ...
... Ambient water temperatures and locations, which are recorded using traditional electronic tags, may also be useful for determining the spawning seasons of individual fish (Yasuda et al., 2010). Smart programming of advanced sensors such as acceleration sensors (Kawabe et al., 2004;Sakamoto et al., 2009) and camera sensor (Kudo et al., 2007) or by varying recording rates (Kawabe et al., 2009) ...
Vertical swimming events (VSEs) of the Japanese flounder, Paralichthys olivaceus, recorded by high-frequency depth data loggers, were analysed to identify spawning events. In total 25,907 VSEs from 10 adult fish were classified into 4 clusters using a k-means method. VSEs in a specific cluster (cluster-S) characterised by accelerated vertical swimming were identified as possible spawning events. Both the descent (0.43 ± 0.22 body length s− 1) and ascent rates (0.43 ± 0.24 body length s− 1) of VSEs in cluster-S were more than 4 times faster than in any other VSE. Our analyses indicated that 4 individuals exhibited the spawning events during the recording periods. The estimated spawning frequency ranged from 0.74 to 0.90 events day− 1. These values were comparable to those obtained in other field and laboratory studies. The spawning condition of fish at the time of recapture was confirmed by separate histological and anatomical observations, which supported the cluster analysis results. These results suggest that a clustering technique can be successfully applied to identify spawning behaviour from time-depth data of free-swimming flatfishes that exhibit vertical swimming movements.
... Over the last few decades, our knowledge of a large range of animals, including aquatic species, has been transformed due to the introduction of new electronic devices for monitoring animal behaviour. Among these devices, data loggers have emerged as a tool for quantifying the underwater behaviour (e.g., Kawabe et al., 2004Kawabe et al., , 2009Sims et al., 2009), ambient environment (e.g., Watanabe et al., 2003;Fedak, 2004), physiological conditions (e.g., Southwood et al., 1999;Froget et al., 2004), and location (e.g., Metcalfe and Arnold, 1997;Block et al., 2001;Mitani et al., 2004;Schofield et al., 2007) of aquatic animals. One disadvantage of data loggers is that they store data in an internal flash memory, which therefore requires their retrieval from the animals to which they are attached. ...
... Therefore, seasonal changes in temperature in the semi-enclosed seas may drive the behavioural decisions that underlie habitat shifts (Sims et al., 2004). The large body size of Japanese flounders makes it possible to track their behaviour using electronic devices, and previous studies have developed methodology to examine the horizontal and vertical movements of flatfish, including the Japanese flounder, using depth data loggers (Metcalfe and Arnold, 1997;Hunter et al., 2003;Kawabe et al., 2009). Here, we used depth-temperature data loggers to examine a possible causal linkage between habitat shifts, water temperature and reproduction in adult Japanese flounder, which sometimes experience the onset of maturation in semi-enclosed seas. ...
... Depth is recorded with ±0.05 m resolution and a full recording range of 200 m; temperature is recorded with a precision of 0.038°C and an accuracy of 0.18°C. If the logger is set to sample less frequently, there is a risk of underestimating the number of vertical activities and underestimating the swimming duration due to extended sampling intervals (Kawabe et al., 2009). However, high-frequency sampling may result in a short overall recording period due to the limited memory capacity of the logger. ...
For ectothermic fish, water temperature may influence the timing and location of reproduction. The water temperature in semi-enclosed bays fluctuates substantially compared to the neighbouring open sea, leading to thermal differences between the bay and the open sea. This phenomenon may stimulate the habitat shifts of seasonally migratory fish. To clarify the effects of temperature on the habitat shifts, we used depth-temperature data loggers to monitor the behaviour of adult Japanese flounder Paralichthys olivaceus (range: 47.0–57.6 cm) in Omura Bay, a typical semi-enclosed bay in Japan. Ten flounder were tagged and released in December, 2007. A total of six loggers and four tagged fish were recovered; two loggers and one tagged fish were retrieved from the Omura Bay, and four loggers and three tagged fish from the East China Sea. The variations in temperature and harmonic constants of the M2 tide extracted from the data logger showed that the emigration of three of the six fish from the bay to the open sea corresponded with the rise in temperature experienced by the fish. The water temperature in the bay continuously decreased and finally fell below the lower threshold of the optimal temperature for hatching of their eggs. Anatomical observations conducted on four individuals recaptured outside the bay revealed the presence of post-ovulatory follicles and/or oocytes at the maturing stage, indicating that they were spawning in the open sea at the time. Vertical swimming activity of the fish was significantly increased after the emigration from the bay, suggesting that spawning, foraging, and movement opportunities were increased. Therefore, it appears that adult Japanese flounder shift their habitats during the reproductive period to find higher temperatures that offer physiological and ecological advantages.
Seasonal changes in habitat use in terms of depth and temperature were estimated for Japanese flounder Paralichthys olivaceus from the Pacific coast of northeastern Japan from 2006 to 2008, using data from trawl and gillnet fisheries logbooks, to which we assigned monthly estimates of bottom temperature. Estimated distributions of flounder for depth and temperature were validated by actual depth and temperature readings from data storage tags (DSTs) attached to flounder, and from collection records by trawl survey. Year-round, flounder > 300 mm in total length were present mainly in areas < 100 m in depth, although their depth range extended to ~ 100 m in summer and ~ 200 m in winter. Flounder experienced cold temperatures (< 10 °C) for several months during winter and spring, and cooler temperatures (< 18 °C monthly mean) in summer, with a range from 4.6 °C to 21.0 °C. This temperature range of the habitat is lower than recorded for this species elsewhere in Japan, and seemed to affect regional life-history traits such as growth and spawning season. DST readings indicated that flounder experienced higher temperatures during vertical swimming behavior than bottom temperatures when the water was stratified (May–October), which may also influence life-history traits.
To elucidate the post-release movement and emigration of juvenile spotted halibut Verasper variegatus, ten hatchery-reared age-0 individuals (10 months old, 17.0–19.7 cm total length) surgically implanted with acoustic transmitters were released near the center of Matsukawa-ura, a shallow brackish lagoon, on 25 November 2009 (water temperature 13.8 °C). They were monitored by ten acoustic receivers for 5 months. Of ten individuals, eight left the release site during December–March. Three of these emigrated to the outer ocean on 17 and 29 January and 30 March 2010, respectively. Juveniles probably started wintering migration in December and January when water temperatures decreased considerably in the lagoon (mean 9.5 and 6.0 °C, respectively). They stopped their migration in the coldest month, February (mean 5.7 °C), and restarted it in March when water temperatures frequently exceeded a plausible threshold for movement (≥6 °C). Statistical analyses revealed that the fish started migration significantly more frequently at nighttime. The migration track of an individual recorded from 11 to 30 March showed gradual nocturnal movements and a slow migration speed (estimated maximum speed 2.2 m/min). Our results revealed that water temperature primarily governed the seasonal timing of nocturnal migratory movements of juvenile spotted halibut.
This review incorporates the available published information on the distribution and dynamics of habitat use for flatfishes based on over 317 published papers in the peer-reviewed literature. This includes the abiotic (temperature, salinity, depth, substratum type) and biotic (vegetation, refuges, prey resources) variables that influence habitat use including the roles of settlement, ontogeny, migrations and short (diel, tidal, seasonal, episodic) and long (annual, decadal) temporal scales. An additional focus is on the spatial dynamics of habitat use with distinction between ‘use’ and ‘selection’ where possible.
Understanding the environmental processes determining the timing and success of reproduction is of critical importance to developing effective management strategies of marine fishes. Unfortunately it has proven difficult to comprehensively study the reproductive behavior of broadcast-spawning fishes. The use of electronic data storage tags (DSTs) has the potential to provide insights into the behavior of fishes. These tags allow for data collection over relatively large spatial and temporal scales that can be correlated to predicted environmental conditions and ultimately be used to refine predictions of year class strength. In this paper we present data retrieved from DSTs demonstrating that events putatively identified as Atlantic cod spawning behavior is tied to a lunar cycle with a pronounced semi-lunar cycle within it. Peak activity occurs around the full and new moon with no evidence of relationship with day/night cycles.
This chapter provides an overview of the principal aspects of flatfish behaviour during the benthic stage of their life history. It concentrates on the activities of spawning, feeding and reactions to predators that enable flatfishes to reproduce, grow and survive. These activities take place over a wide range of spatial scales from localized foraging to long-distance migrations and a brief account of movement patterns that have evolved to make the most effective use of the environment is included. Finally, aspects of flatfish behaviour that are important in relationships with humans, including the design of fishing gear, culturing practices and stock enhancement are discussed.
