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Scientists and managers have become increasingly interested in how pelagic marine protected areas (PMPAs), or protected areas away from the coast, can be used to protect pelagic species. Subsurface-predator facilitated foraging (‘facilitated foraging’) between seabirds and subsurface predators, such as tunas, is a key ecological interaction in the...
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... has been an increasing trend in the creation of mostly pelagic marine protected areas (PMPAs) to protect ocean ecosystems ( Table 1). Marine ecosystems encompass 99% of the earth’s biosphere volume (Angel 1993), and the vast majority of this volume occurs in the pelagic realm, or areas away from the coastal zone (e.g. non-neritic). Protection of pelagic ecosystems, in addition to coastal regions, is necessary to meet global marine conservation targets, such as the Convention on Biological Diversity’s call to establish 10% of the worlds’ oceans as MPAs by 2020 (Convention on Biological Diversity 2010). Additionally, pelagic ecosystems provide > 80% of global fish production (Pauly et al. 2002), are critical in the regulation of the Earth’s climate (Field 1998), and support the majority of marine life during all or some part of their life history (Hays et al. 2005). Still, pelagic ecosystems face a number of threats, including overfishing, pollution, climate change, and species introductions (Halpern et al. 2008), and PMPAs have been proposed as one means of ameliorating these effects (Game et al. 2009). Protecting pelagic or wide-ranging species from effects is often cited as one of the primary reasons for designating PMPAs, but the areas must be large enough to incorporate significant portions of the habitat of far-ranging or migratory animal species or protect crucial life history phases (Hyrenbach et al. 2000, Norse 2005, Alpine & Hobday 2007, Ardron et al. 2008, Game et al. 2009). Additionally, protective measures must re flect effects managers are attempting to ameliorate (e.g. fishing must be reduced or prohibited to prevent overfishing), and areas must be effectively enforced (Walmsley & White 2003). Several PMPAs, particularly in the Central Pacific and Indian Oceans (e.g. Chagos Marine Reserve, Phoenix Islands Protected Area, Papah naumoku kea Marine National Monument [MNM], and the Pacific Remote Islands MNM), are now in place (Table 1), and managers are beginning to grapple with the dif- ficulties of developing and monitoring indicators of effectiveness for these protected areas within an eco- system-based management context. This is particularly difficult in PMPAs because of the dynamic processes that occur in pelagic ecosystems (e.g. eddies and fronts) and the highly mobile species that are the focus of protection (Game et al. 2009). Tropical seabirds are 1 example of a highly mobile species group that managers are aiming to protect. Many tropical seabirds are far-ranging foragers, breeding on small islands and atolls and carving out an existence in largely oligotrophic parts of the oceans (Owen 1981, Ballance et al. 1997). Many rely on dynamic and ephemeral oceanographic processes to forage. PMPAs may be of particular ecological sig- nificance to tropical seabirds because they are central place foragers during the breeding season, when they must return to colonies to incubate eggs and feed chicks (Ashmole & Ashmole 1967, Ballance et al. 2006). Seabirds may travel thousands of kilometers in a single foraging trip, but their long-distance movements are centered on the colony during the breeding season (King 1974, Flint 1991, Laniawe 2008, Catry et al. 2009a). This increases the chances that protection from PMPAs may influence seabirds throughout some or all of their foraging range be cause foraging opportunities may be increased through the additional protection of the resources they depend on. PMPAs that reduce or eliminate commercial fishing may influence seabirds via direct and indirect mechanisms. (We refer to PMPAs that reduce or eliminate fishing effort when referring to PMPAs for the remainder of the text.) Reduced fishing within PMPAs may lower seabird bycatch or diminish the opportunities for seabirds to forage on fishery discards (Tasker et al. 2000, Lewison & Crowder 2003, Votier et al. 2004). Additionally, reduced pressure of some fisheries may increase foraging opportunities for seabirds by increasing the abundance of prey species. However, unlike the majority of temperate seabirds, most tropical seabirds lack deep diving capabilities and instead must forage in the top-most surface layer (Ashmole & Ashmole 1968, Harrison et al. 1983). This has led to the evolution of subsurface- predator facilitated foraging (hereafter referred to as ‘facilitated foraging’) (Fig. 1). In this interaction, large pelagic fishes, such as tunas, drive forage fish into surface waters, making them available to surface predators (Murphy & Ikehara 1955, Ashmole & Ashmole 1967). Though this interaction occurs in many parts of the world (Burger 1988), it is of particular importance in the tropical waters of the world’s oceans because it is one of the primary means by which tropical seabirds forage (Au & Pitman 1986, Spear et al. 2007). Because it is a critical interaction for seabirds, a reduction or cessation of fishing efforts targeting prey species or subsurface predators within tropical PMPAs may increase subsurface predator or prey density, resulting in more foraging opportunities for seabirds. Facilitated foraging has been relatively well studied in the Eastern Tropical Pacific (ETP) (see Au & Pitman 1986, Spear & Ainley 2005, Spear et al. 2007), but it has been largely unstudied in the Central Tropical Pacific (CTP) (but see Ashmole & Ashmole 1967), although distinct differences in facilitated foraging occur between the 2 systems. For example, tunas, primarily skipjack Katsuwonus pelamis and yellow fin Thunnus albacares , are the main subsurface pred ators in the CTP, in contrast to dolphins and tunas in the ETP (Spear et al. 2007). These species have different vertical and horizontal movement patterns, which may influence facilitated foraging be havior. Additionally, seabird assemblages in the CTP differ from those in the ETP (Ashmole & Ashmole 1967). Still, it is unknown how variability in the interaction influences seabird populations. Given the corre lations previously identified between fishery development and seabird crashes in many areas of the world (Harrison et al. 1983, Cury et al. 2011), there is a need to understand how seabirds interact with subsurface predators, particularly commercially important species, such as skipjack and yellowfin tunas, across the range where these interactions occur. These interactions are of particular interest to managers of large PMPAs in tropical oceans as seabirds are often a guild that managers aim to protect. One such MPA is the US Pacific Remote Islands Marine National Monument (PRIMNM), created in 2009 by Presidential Proclamation (Federal Register 2009), resulting in 225 038 km 2 of protected area in the CTP. It includes the far-flung and mostly unpop- ulated US territories of Wake Island, Johnston Atoll, Palmyra Atoll and Kingman Reef, Jarvis Island, and Howland and Baker Islands. These islands and atolls are home to as many as 4.4 million breeding seabirds representing at least 16 species (Table 2). Co-managed by the US National Oceanic and Atmospheric Administration (NOAA) and the US Fish and Wildlife Service (USFWS), monument managers want to know if the PMPA is likely to have a positive effect on seabirds and, subsequently, how to adequately monitor and manage seabird and pelagic fish populations. To assess our current state of knowledge of facilitated foraging in the CTP and to determine the key research questions and methodologies for managing human activities that may influence facilitated foraging, we conducted a literature review and held an expert workshop. We focused specifically on the seabirds breeding on the PRIMNM islands and atolls (Table 2), though this information is applicable to other tropical areas. We further focused on a set of topics we identified in conjunction with managers at the NOAA Pacific Islands Regional Office, which is responsible for PRIMNM management. These topics were intended to focus future research on key ele- ments of seabird and subsurface predator ecology and included the determination of the importance of subsurface predators to tropical seabird foraging, the distributions of seabirds and tunas, and the foraging behaviors and diets of seabirds in the PRIMNM re gion. At the heart of this review is this question: how do subsurface predator populations influence seabird population behavior and reproductive performance, and how can this knowledge be integrated into management of seabird and subsurface predator species in PMPAs? Below, we review current re search aimed at answering this ...
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Many species of tropical seabirds rely on subsurface predators such as tuna and dol- phins to drive prey close to the ocean's surface. We observed seabird foraging events from fishing vessels around the island of Oahu, Hawaii, to determine the prevalence and relative importance of different subsurface predators to seabird foraging. Sixty-nine seabi...
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... MPAs (Breen et al., 2016;Maxwell & Morgan, 2013;Paiva et al., 2015). programme of editorial assistance, and we thank Daniel Brooks for managing it. ...
1. Seabirds, particularly albatrosses, are among the most threatened birds as a result
of their continuous exposure to anthropic pressures including interaction with
commercial fisheries, climate change and pollution. Several studies that have
focused on the spatial distribution of foraging seabirds have identified a certain
level of segregation between age classes.
2. The black-browed albatross Thalassarche melanophris is the most abundant
albatross species in the South-west Atlantic Ocean and the main pelagic seabird
interacting with a range of fishing fleets. There is a considerable lack of
knowledge about the biology of immature individuals and on habitat suitability of
the species during non-breeding season (winter).
3. The aim of this study was to assess the foraging habitat suitability of the blackbrowed
albatross in the South-west Atlantic during the austral winter, analysing
differences between adults and immatures individuals.
4. Habitat suitability models were based on foraging locations recorded by
15 satellite transmitters deployed on six adults and nine immature individuals
between 2011 and 2015. Remotely sensed oceanographic data were used to
characterize suitable foraging habitat for the albatrosses.
5. Differences were found in foraging habitat suitability by age class, with adult
selecting areas located in deeper waters over the continental shelf break as well
as in neritic zones under cooler water temperatures, whereas immature
individuals foraged chiefly off coastal waters having more moderate temperatures.
6. Knowing habitat suitability and segregation patterns within-species is key for the
conservation of critical marine habitats given that, by only considering one age
class, other important habitats would be neglected and not considered in
conservation efforts to mitigate threats such as incidental mortality. It is
important to include all age classes when studying patterns of associations with
threats, such as fishing activity as a proxy of risk of bycatch, and for the
development of Marine Protected Areas.
... The number of existing no-take MPAs exceeds 50% of all the MPAs in China Seas (Bohorquez et al., 2021), but only 11 of them are primarily designed to protect fish species. Other no-take MPAs might have protected fish as well (Maxwell & Morgan, 2013), but only 25% of them are larger than 100 km 2 , limiting their capacity for conservation. Area size is one of the important factors influencing the functionality of no-take MPAs (Vandeperre et al., 2011). ...
Climate change is one of the major threats to coastal fish biodiversity, and optimization of no-take marine protected areas (MPAs) is imminent. We predicted fish redistribution under climate change in coastal China Seas with joint species distribution modeling and prioritized areas for conservation with Zonation, for which we used core area zonation (CAZ) and additive benefit function (ABF). Based on our results, we devised an expansion plan of no-take MPAs. Under climate change, fish were redistributed northward along the coast. These redistributions were segmented by the Yangtze River estuary and its adjacent waters, indicating a possible biogeographical barrier. Under CAZ and ABF, significantly more fish habitat was conserved than under random prioritization (p < 0.001, Cohen's d =-0.36 and-0.62, respectively). The ABF better represented areas with higher species richness, whereas CAZ better represented core habitats for species with narrow distributions. Without accounting for species redistribution, the expanded MPAs were mainly distributed in the northwest of the South China Sea, the East China Sea, the north of the Yellow Sea, and the west of the Bohai Sea. When accounting for species redistribution, the proposed MPAs were mainly distributed in the north of the Bohai Sea and southwest of the Yellow Sea, corresponding to the northern species redistributions. These MPAs conserved less habitat for fishes at present but protected more and better quality habitat for fishes in 2050 and 2100 than those MPAs that did not account for species redistribution, indicating improved fish conservation under climate change. Incorporating species redistribution and trade-offs between areas with high species richness and areas that contain habitats for rare species are suggested to address coastal fish conservation under climate change. This work provides valuable information for fish conservation and is a precursor to systematic conservation planning along the coastlines of China Seas. Mejora de la eficiencia y la resiliencia de las áreas marinas protegidas con veda para la conservación de peces bajo el cambio climático en la costa de los mares de China Resumen: El cambio climático es una de las principales amenazas para la biodiversi-dad de peces costeros, y la mejora de las área marinas protegidas (AMP) con vedas es inevitable. Pronosticamos la redistribución de los peces por el cambio climático en la costa de los mares de China con un modelo de distribución de especies y las áreas pri-orizadas para la conservación con Zonation, para el cual usamos zonación de las áreas núcleo (ZAN) y la función del beneficio aditivo. (FBA). Con base en nuestros resultados, diseñamos un plan de expansión de AMP con veda. Con el cambio climático, los peces se redistribuyeron hacia el norte a lo largo de la costa. Esta redistribución fue segmen-tada por el estuario del río Yangtze y las aguas vecinas, indicador de una posible barrera Conservation Biology. 2023;e14174. biogeográfica. Con la ZAN y la FBA, se conservó una cantidad significativa de peces en comparación con una priorización aleatoria (p < 0.001, d de Cohen =-0.36 y-0.62, respec-tivamente). La FBA representó de mejor manera las áreas con una riqueza de especies elevada, mientras que la ZAN representó de mejor manera los hábitats nucleares de las especies con una distribución reducida. Sin contar la redistribución de las especies, las AMP expandidas se localizaron principalmente en el noroeste del Mar del Sur de China, del Mar del Este de China, al norte del Mar Amarillo y al oeste del Mar Bohai. Cuando consideramos la redistribución de las especies, las AMP propuestas se localizaron princi-palmente al norte del Mar de Bohai y al suroeste del Mar Amarillo, lo que corresponde a la redistribución hacia el norte de las especies. Estas AMP conservaron un menor hábi-tat de los peces en el presente pero protegieron un mejor hábitat y de mayor calidad para los peces en 2050 y 2100 que las AMP que no consideraron la redistribución de especies, lo que indica una mejora en la conservación de peces bajo el cambio climático. Se sugiere que la incorporación de la redistribución de especies y las compensaciones entre las áreas con una riqueza de especies elevada y las áreas que albergan hábitats para especies raras abordarán la conservación de peces costeros bajo el cambio climático. Esta investigación proporciona información valiosa para la conservación de peces y es un precursor de la planeación sistemática de la conservación a lo largo de la costa de los mares de China.
... A partir de la información resultante, los tomadores de decisión pueden establecer áreas prioritarias o bien revisar el grado de implementación y efectividad de las áreas protegidas vigentes (Maxwell et al., 2014(Maxwell et al., , 2015. Dadas las características de las historias de vida de ciertas especies de aves marinas, tales como su longevidad, amplia distribución y superposición con importantes factores de estrés antropogénico, estos depredadores pueden utilizarse como indicadores biológicos para identi car y priorizar áreas para la conservación marina (Breen et al., 2016;Maxwell y Morgan, 2013;Paiva et al., 2015). El Albatros Ceja Negra (Thalassarche melanophris) es una especie que puede vivir más de 60 años, sus poblaciones de Islas Malvinas (y en parte las de Islas Georgias del Sur) se distribuyen ampliamente en el Atlántico Sudoccidental Grémillet et al., 2000;Paz et al., 2021;Phillips et al., 2004;Ponchon et al., 2019), y es la principal especie que se asocia a buques pesqueros, sufriendo altos niveles de captura incidental en pesquerías de la región (Bugoni et al., 2008;Favero et al., 2011Favero et al., , 2013Jiménez et al., 2009;Neves et al., 2007;Paz et al., 2018;Seco Pon et al., 2015;Sullivan et al., 2006) (Fig. 1). ...
La planificación espacial marina es una herramienta de gestión útil para la conservación de la biodiversidad. Depredadores como las aves marinas pueden utilizarse como indicadores biológicos, tanto para monitorear el estado de los ecosistemas marinos como para identificar y priorizar áreas para la conservación marina. El Albatros Ceja Negra (Thalassarche melanophris) es una de las especies de aves marinas más abundante del Atlántico Sudoccidental y listada como Vulnerable a nivel nacional, siendo las altas tasas de captura incidental en buques pesqueros una de las principales causas de esta categorización. El presente estudio tuvo como objetivo definir áreas prioritarias para la conservación en el Mar argentino, utilizando al Albatros Ceja Negra como estudio de caso y especie clave. Se realizaron análisis de priorización espacial utilizando información de idoneidad de hábitat de la especie, así como variables antrópicas relacionadas a la actividad pesquera (esfuerzo pesquero y áreas de veda) como limitantes o forzantes en la selección de áreas. Las áreas prioritarias de base (sin considerar la actividad pesquera) identificadas para la conservación de la especie se ubicaron sobre la isobata de 50mdesde el norte de la Península Valdés hasta Mar del Plata, y otras en la desembocadura del Río de la Plata, sobre la isobata de 50m en la Plataforma Bonaerense y una en la zona externa de El Rincón, dependiendo de los años utilizados para el análisis. El análisis de áreas prioritarias incluyendo capas de actividad pesquera permitió la identificación de áreas prioritarias para la conservación dentro de las zonas de veda ya establecidas. La información presentada es útil como insumo para el desarrollo y gestión de Áreas Marinas Protegidas y Otras Medidas Efectivas de Conservación Basadas en Áreas e inclusive el ordenamiento de actividades antrópicas en el Mar Argentino.
Citar como: Paz J A, Copello S, Seco Pon J P, Favero M (2023) Áreas de importancia para la conservación de aves marinas en el Mar Argentino: el Albatros Ceja Negra (Thalassarche melanophris) como especie clave. Informes científico-técnicos del Instituto de Investigaciones Marinas y Costeras N°22 (UNMdP-CONICET). 20pp. ISSN 2796-9088
https://www.iimyc.gob.ar/iimyc/wp-content/uploads/2023/12/Informe22.pdf
... Not only did the forceful removal of this satellite tag cause traumatic injury to the shark, but it negatively impacts the entire species through loss of invaluable data needed for increased protection. Telemetry data have been used to effect policy change from scales of only a few kilometers up to open oceans, influenced Marine Protected Area designs, contributed to stock management, and helped change the conservation status of marine species [33][34][35][36][37]. While this injury provided the first record of fin regeneration in silky sharks, the data collected by the satellite tag could have provided data to better protect and conserve an entire species. ...
Tissue regeneration and wound healing remain extremely understudied in elasmobranchs as many wounds are recorded through one-off opportunistic observations with an inability for long-term monitoring of individuals. This study demonstrates partial fin regeneration of a silky shark (Carcharhinus falciformis) almost one year after a traumatic injury that resulted in a 20.8% loss of the first dorsal fin. The shark was photographed 332 days after the recorded injury with a newly shaped dorsal fin that had healed to 87% of the original size. Photographs provided by divers allowed for accurate measurements of fin growth, confirming an approximate 10.7% increase in fin area, indicative of tissue regeneration. Wound healing rate was calculated to conclude that the initial wound reached complete closure by day 42, which is analogous with other elasmobranch healing rates. Prior to this study, only one other record of dorsal fin regeneration had been documented in a whale shark. This provides the first evidence of dorsal fin regeneration in a silky shark and contributes to the limited studies of wound healing rates in sharks. This newfound insight into tissue regeneration and wound healing underscores the importance of further research to understand how they respond to traumatic injury in the face of mounting environmental challenges, both natural and anthropogenic. Additionally, this study exemplifies the power of collaboration between researchers and the public, including photographers and divers, to expand the scope of research studies and bridge the gap between science and society.
... Reynolds et al. (2019) highlighted the importance of increasing sea surface temperatures (SST) and tuna extraction by fisheries in explaining long-term changes in the trophic ecology of sooty terns breeding on Ascension Island. Sooty terns are heavily reliant on large schools of surface-swimming tunas, such as yellowfin (Thunnus albacares) and skipjack (Katsuwonus pelamis) tuna, to drive their common prey to the ocean surface, where many tropical seabirds forage in so-called « facilitated foraging » (Ashmole, 1963a;Au and Pitman, 1986;Ballance and Pitman, 1999;Maxwell and Morgan, 2013). Sooty terns are therefore susceptible to any over-exploitation and major declines in these associated species (Cullis-Suzuki and Pauly, 2010;Juan-Jordá et al., 2011). ...
Mercury (Hg) is a highly toxic metal that adversely impacts human and wildlife health. The amount of Hg released globally in the environment has increased steadily since the Industrial Revolution, resulting in growing contamination in biota. Seabirds have been extensively studied to monitor Hg contamination in the world's oceans. Multidecadal increases in seabird Hg contamination have been documented in polar, temperate and subtropical regions, whereas in tropical regions they are largely unknown. Since seabirds accumulate Hg mainly from their diet, their trophic ecology is fundamental in understanding their Hg exposure over time. Here, we used the sooty tern (Onychoprion fuscatus), the most abundant tropical seabird, as bioindicator of temporal variations in Hg transfer to marine predators in tropical ecosystems in response to trophic changes and other potential drivers. Body feathers were sampled from 220 sooty terns, from museum specimens (n = 134) and free-living birds (n = 86) from Ascension Island, in the South Atlantic Ocean, over 145 years (1876-2021). Chemical analyses included (i) Hg (total- and methyl-Hg), and (ii) carbon (δ1³C) and nitrogen (δ15N) stable isotopes, as proxies of foraging habitat and trophic position, respectively, to investigate the relationship between trophic ecology and Hg contamination over time. Despite current regulations on its global emissions, mean Hg concentrations were 58.9% higher in the 2020s (2.0 μg g-1, n = 34) than in the 1920s (1.2 μg g-1, n = 107). Feather Hg concentrations were negatively and positively associated with δ1³C and δ15N values. The sharp decline of 2.9‰ in δ1³C values over time indicates ecosystem-wide changes (shifting primary productivity) in the tropical South Atlantic Ocean and can help explain the observed increase in tern's feather Hg concentrations. Overall, this study provides invaluable information on how ecosystem-wide changes can increase Hg contamination of tropical marine predators and reinforces the need for long-term regulations of harmful contaminants at the global scale.
... The observed redistribution of fish based on the water flow regime resulted in the Southwest Florida Water Management District changing their practices to release water from the lake more slowly rather than large pulse events, reducing physiological stress in bull sharks and sawfish. At a much larger scale, tracking data for several seabird species, along with sea turtles, sharks, and marine mammals, showed that the original boundaries of two large-scale MPAs, Papahanaumokuakea and the Pacific Remote Islands Marine National Monuments, were not capturing the entire habitat of these species and were key components of the scientific justification for the expansion of these MPAs [85][86][87]. In 2016, Papahanaumokuakea was extended to 1.5 million km 2 , which is three times its original size, and the Pacific Remote Islands increased to 1.27 million km 2 , six times its original size ( Figure 1, example 28). . ...
Відстеження та інформування за ходом товаропросування харчового продукту є основою для забезпечення ідентифікації та належного керування всіма відповідними небезпечними чинниками та ризиками виробництва харчового продукту на кожній ланці у межах харчового
... In protected areas, fish population structures should shift toward older, larger individuals, allow more development time for young, and include greater size class diversity (Lester et al., 2009) and these changes should also provide more food for predators like seabirds and cetaceans, though these trophic relationships are complex at Palmyra (Bradley et al., 2017). Seabirds depend on subsurface predators for foraging (Au and Pitman, 1986), and can benefit from increased access to prey via facilitated foraging in concert with subsurface predators (Maxwell and Morgan, 2013). Decreased fisheries interactions, reduced entanglements, and reduced by-catch are also expected (Handley et al., 2020), which could benefit reef manta rays and green sea turtles. ...
... In pelagic habitats, the yellowfin tuna is a large, economically important pelagic fish that is wide-ranging and can be found at depths of up to several hundred meters, making extensive use of the epipelagic zone (Fonteneau and Hallier, 2015;Lam et al., 2020). Yellowfin tuna also shoal prey species, facilitating foraging for other predators and providing an important ecosystem service (Au and Pitman, 1986;Maxwell and Morgan, 2013). Seabirds (sooty tern, red-footed booby, great frigatebird) are central-place foragers when caring for offspring and are constrained by how far they can travel from the nest to search for food. ...
... Yellowfin tuna had the largest mean ranges (Fig. 3A), but movement patterns within PRIMNM are unknown. Sooty terns and great frigatebirds rely on sub-surface predators to shoal prey to the surface (Au and Pitman, 1986;Maxwell and Morgan, 2013) and at Palmyra, great frigatebirds foraged both inside and outside MPA boundaries (Gilmour et al., 2019;Fig. 3B). ...
Marine protected area (MPA) designs, including large-scale MPAs (LSMPAs; >150,000 km2), mobile MPAs (fluid spatiotemporal boundaries), and MPA networks, may offer different benefits to species and could enhance protection by encompassing spatiotemporal scales of animal movement. We sought to understand how well LSMPAs could benefit nine highly-mobile marine species in the tropics now and into the future by: 1) evaluating current range overlap within a LSMPA; 2) evaluating range overlap under climate change projections; and 3) evaluating how well theoretical MPA designs benefit these nine species. We focused on Palmyra Atoll and Kingman Reef, a 2000 km2 area within the 1.2 million km2 U.S. Pacific Remote Islands Marine National Monument (PRIMNM) that contains marine megafauna (reef and pelagic fishes; sea turtles; seabirds; cetaceans) reflecting different behaviors and habitat use. Our approach is useful for evaluating the effectiveness of the Palmyra-Kingman MPA and PRIMNM in protecting these species, and tropical LSMPAs in general, and for informing future MPA design. Stationary MPAs provided protection at varying scales. Reef manta rays (Mobula alfredi), grey reef sharks (Carcharhinus amblyrhynchos), green sea turtles (Chelonia mydas), and bottlenose dolphins (Tursiops truncatus) had overall small ranges (
... Seabirds and cetaceans often associate at sea, either through overlapping spatial distributions when targeting the same foraging habitats (Yen et al., 2004;Cox et al., 2018;Sutton et al., 2019), or by maximizing foraging efficiency when feeding together (Harrison, 1979;Ballance et al., 1997;Maxwell and Morgan, 2013). In these feeding associations, seabirds are the likely beneficiaries as cetaceans make food more accessible by driving prey that is typically out of reach toward the surface and sometimes concentrating prey into tight groups (Evans, 1982). ...
With accelerating climate variability and change, novel approaches are needed to warn managers of changing ecosystem state and to identify appropriate management actions. One strategy is using indicator species—like seabirds as ecosystem sentinels—to monitor changes in marine environments. Here, we explore the utility of western gulls (Larus occidentalis) breeding on Southeast Farallon Island as a proxy of ecosystem state in coastal California by investigating the interannual variability in gull foraging behavior from 2013 to 2019 in relation to upwelling conditions, prey abundances, and overlap with humpback whales (Megaptera novaeangliae) as gulls frequently feed in association with whales. Western gulls have a flexible diet and forage on land and at-sea. We combined gull GPS tracking data during the incubation phase, ecosystem survey data on multiple predator and prey species, and derived oceanographic upwelling products. When foraging at sea, gulls overlapped with cool upwelled waters. During 2015–2017, 25% more gull foraging trips visited land than in other years, where land trips were on average ∼8 h longer and 40% further than sea trips, which coincided with high compression of coastally upwelled waters (habitat compression) in 2015–2016. Gull foraging behavior was related to local prey abundances, where more foraging occurred near shore or on land when prey abundances were low. However, visual surveys indicated that ∼70% of humpback whale observations co-occurred with gulls, and the year with the most foraging on land (2017) corresponded to regionally low relative whale abundances, suggesting gull movement patterns could be an indicator of whale presence. Further, both whales and gulls forage near-shore under high upwelling habitat compression and low krill abundance. Hence, the deployment of year-round tags on gulls with the capability of near real-time data accessibility could provide important fine-scale metrics for conservation and management of the threatened yet recovering eastern Pacific humpback whale population between infrequent and coarse surveys. Entanglement in fishing gear and ship strikes are major inhibitors to whale recovery and have increased concomitantly with human use of ocean resources. Moreover, as climate variability and change increase, novel indicators should be explored and implemented to inform marine spatial planning and protect species across multiple scales from new risks.
... Reynolds et al. (2019) highlighted the importance of increasing sea surface temperatures (SST) and tuna extraction by fisheries in explaining long-term changes in the trophic ecology of sooty terns breeding on Ascension Island. Sooty terns are heavily reliant on large schools of surface-swimming tunas, such as yellowfin (Thunnus albacares) and skipjack (Katsuwonus pelamis) tuna, to drive their common prey to the ocean surface, where many tropical seabirds forage in so-called « facilitated foraging » (Ashmole, 1963a;Au and Pitman, 1986;Ballance and Pitman, 1999;Maxwell and Morgan, 2013). Sooty terns are therefore susceptible to any over-exploitation and major declines in these associated species (Cullis-Suzuki and Pauly, 2010;Juan-Jordá et al., 2011). ...
... Thirdly, as both our echosounder mounts (poleor towed-body mounted) sampled at depth (> 3 m for the pole mount) the near-surface portion of the fish assemblage is likely not insonified. Surface aggregation is a major mechanism of trophic energy transfer in the tropics, whereby prey fish are eaten by predators such as tunas, sharks, cetaceans and seabirds (Maxwell and Morgan 2013). In the future, there may be considerable value in applying acoustic methods that are able to capture schools in the near-surface, for example, through horizontally facing echosounders, or side-scan sonar. ...
The pelagic ecosystem is the ocean's largest by volume and of major importance for food provision and carbon cycling. The high fish species diversity common in the tropics presents a major challenge for biomass estimation using fisheries acoustics, the traditional approach for evaluating mid-water bio-mass. Converting echo intensities to biomass density requires information on species identity and size, which are typically obtained by lethal means, and thus unsuitable in the portion of the ocean that is 'no take'. To improve conservation and ecosystem based management, we present a procedure for determining fish biomass density, using data on species identity, relative abundance, and lengths obtained from stereo baited remote underwater video systems (stereo-BRUVS) to inform the scaling of echosounder survey data (at 38 kHz). We apply the procedure in the British Indian Ocean Territory marine protected area, using acoustic data from 3025 km of survey transects and 546 BRUVS deployments recording relative abundance and size of 12,335 individual fish. Using a Generalised Additive Model of biomass density (GAM, adjR 2 = 0.61) we predict, on the basis of oceanographic conditions and bathymetry, that the top 200 m pelagic ecosystem in the Chagos Archipelago, some 118,324 km 2 , held 3.84 (2.66, 5.62, 95% CI), 33.09 (23.41, 47.35) and 4.08 (3.1, 5.44) million tonnes of fish in November 2012, January 2015, and February 2016, respectively. Our non-extractive procedure yields ecologically credible patterns in biomass across multiple temporal (hours and years) and spatial (metres and kilometres) scales, and marks an improvement on the use of echo intensity alone as a biomass proxy. High seasonal and interannual variability has implication for pelagic fish monitoring.
