Plasticity in the diel vertical movement of two pelagic predators (<i>Prionace glauca</i> and <i>Alopias vulpinus</i>) in the southeastern Indian Ocean

Heard, Matthew S.; Rogers, Paul; Bruce, Barry D.; Humphries, Nicolas E.; Huveneers, Charlie

doi:10.1111/fog.12245

Cited by 13 publications

(6 citation statements)

References 72 publications

(141 reference statements)

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“…It is worth noting that latitudinal species shifts in response to warming can be misleading with some pelagic species migrating vertically not latitudinally (Perry et al, 2005;Beaugrand and Kirby, 2018) and this may be the case with some pelagic shark species. In Australian waters, pelagic sharks have been recorded regulating their depth to occupy regions of favorable temperatures, although this behavior could also be related to prey movements (Rogers et al, 2009;Stevens et al, 2010;Heard et al, 2017) as well as habitat suitability.…”

Section: Discussionmentioning

confidence: 99%

“…The Australian Exclusive Economic Zone (EEZ) is already being impacted by climate change with waters off south-east Australia warming at almost four times the global average (Oliver et al, 2017) and range extensions already documented in several fish species (Last et al, 2011). Australia has one of the world's most diverse communities of sharks, with 182 recognized species (Simpfendorfer et al, 2019), and SST has been shown consistently to be a strong predictor of pelagic shark occurrence in Australian waters (Rogers et al, 2009(Rogers et al, , 2015Stevens et al, 2010;Heard et al, 2017;Birkmanis et al, 2020). It is therefore important to investigate the likely impact of temperature changes on pelagic shark distribution and the location of suitable habitat on a continental scale if these species are to be appropriately managed into the future -especially if such changes may require a reassessment of interactions with fisheries in the future.…”

Section: Introductionmentioning

confidence: 99%

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Future Distribution of Suitable Habitat for Pelagic Sharks in Australia Under Climate Change Models

et al. 2020

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Global oceans are absorbing over 90% of the heat trapped in our atmosphere due to accumulated anthropogenic greenhouse gases, resulting in increasing ocean temperatures. Such changes may influence marine ectotherms, such as sharks, as their body temperature concurrently increases toward their upper thermal limits. Sharks are high trophic level predators that play a key role in the regulation of ecosystem structure and health. Because many sharks are already threatened, it is especially important to understand the impact of climate change on these species. We used shark occurrence records collected by commercial fisheries within the Australian continental Exclusive Economic Zone (EEZ) to predict changes in future (2050-2099) relative to current (1956-2005) habitat suitability for pelagic sharks based on an ensemble of climate models and emission scenarios. Our predictive models indicate that future sea temperatures are likely to shift the location of suitable shark habitat within the Australian EEZ. On average, suitable habitat is predicted to decrease within the EEZ for requiem and increase for mackerel sharks, however, the direction and severity of change was highly influenced by the choice of climate model. Our results indicate the need to consider climate change scenarios as part of future shark management and suggest that more broad-scale studies are needed for these pelagic species.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Future Distribution of Suitable Habitat for Pelagic Sharks in Australia Under Climate Change Models

et al. 2020

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“…Although probably not high conservation priorities for the IOTC, it is possible that some of these species are caught in tuna gears. The Indian Ocean contains numerous seamounts that are relatively shallow, and where many elasmobranchs make diurnal migrations through wide ranges of the water column, making them simultaneously epipelagic, mesopelagic and bathypelagic (Heard, Rogers, Bruce, Humphries, & Huveneers, 2018; Sims et al, 2006; Speed, Field, Meekan, & Bradshaw, 2010; WWF, 2020). The encounterability attribute could be improved by estimating the distribution of species and fishing effort throughout the depth range, at least by the susceptibility group (e.g.…”

Section: Discussionmentioning

confidence: 99%

Spatially explicit risk assessment of marine megafauna vulnerability to Indian Ocean tuna fisheries

et al. 2022

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By‐catch is the most significant direct threat marine megafauna face at the global scale. However, the magnitude and spatial patterns of megafauna by‐catch are still poorly understood, especially in regions with very limited monitoring and expanding fisheries. The Indian Ocean is a globally important region for megafauna biodiversity and for tuna fisheries, but has limited by‐catch data. Anecdotal and scattered information indicates high by‐catch could be a major threat. Here, we adapt a Productivity Susceptibility Analysis tool designed for data‐poor contexts to present the first spatially explicit estimates of by‐catch risk of sea turtles, elasmobranchs, and cetaceans in the three major tuna fishing gears (purse seines, longlines, and drift gill nets). Our assessment highlights a potential opportunity for multi‐taxa conservation benefits by concentrating management efforts in particular coastal regions. Most coastal waters in the northern Indian Ocean, including countries that have had a minimal engagement with regional management bodies, stand out as high risk for fisheries interactions. In addition to species known to occur in tuna gears, we find high vulnerability to multiple gear types for many poorly known elasmobranchs that do not fall under any existing conservation and management measures. Our results indicate that current by‐catch mitigation measures, which focus on safe‐release practices, are unlikely to adequately reduce the substantial cumulative fishing impacts on vulnerable species. Preventative solutions that reduce interactions with non‐target species (such as closed areas or seasons, or modifications to gear and fishing tactics) are crucial for alleviating risks to megafauna from fisheries.

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“…In addition to the effect of climate change due to the physiological and biological characteristics of the species, their shifts in distribution could be related to their biological interactions with other organisms (Gervais et al, 2020), since the first response of species to altered environmental conditions is to adjust their behavior (Wong and Candolin, 2015). One such adjustment is distribution shifts in apex predators such as the large sharks (Heard et al, 2017) because novel combinations of prey species could generate reorganization of species, even among the trophic webs (Lurgi et al, 2012;Cameron et al, 2019). It has also been observed that expansion of the distribution range is dominated by dietary generalist species (Evans and Moustakas, 2018;Bartley et al, 2019).…”

Section: Discussionmentioning

confidence: 99%

Evaluation of Shifts in the Potential Future Distributions of Carcharhinid Sharks Under Different Climate Change Scenarios

et al. 2022

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Climate change is currently considered one of the main phenomena affecting marine species through expansion or contraction of their distribution. Being ectothermic organisms, sharks of the family Carcharhinidae could be highly susceptible to the effects of climate change. These sharks are of great ecological importance, which is reflected in their role in the integrity of coastal and oceanic ecosystems as top predators that act to maintain the stability of the food chain, as well as providing economic value through fishing, consumption, and ecotourism. Currently, their populations are threatened by fishing pressure and anthropogenic activities, including meeting the demand for shark fins. Despite the ecological and economical importance of carcharhinid sharks, knowledge regarding how they are impacted by climate change remains scarce. Ecological niche modeling is a tool that allows analysis of future potential distributions under different climate change scenarios and could contribute to future planning activities and improved conservation outcomes for sharks. We generated models in Maxent in order to predict the potential geographic distribution of 25 carcharhinid sharks that inhabit Mexican waters, projecting this onto future climate change scenarios (RCP2.6, RCP4.5, RCP6.0, and RCP8.5) to calculate the potential losses and gains in their distribution areas by the year 2050. The greatest shifts in suitable areas were observed for the sharks Triaenodon obesus (gained area) and Carcharhinus porosus (lost area). Overall, under all four RCP future scenarios, six species presented gains in suitable area and 19 species presented losses. The greatest loss of suitable area for carcharhinid sharks was found with RCP8.5; however, under this high-emissions global warming scenario, seven species actually showed an increase in distribution area. Our results therefore indicate that climate change could reduce suitable areas for most of the species by 2050. Assessment of the distribution of shark species under climate change is urgently required in order to prioritize conservation efforts toward the most vulnerable species and to ensure the natural function of marine ecosystems, thus maintaining the important ecosystem services they provide to human society.

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Plasticity in the diel vertical movement of two pelagic predators (Prionace glauca and Alopias vulpinus) in the southeastern Indian Ocean

Cited by 13 publications

References 72 publications

Future Distribution of Suitable Habitat for Pelagic Sharks in Australia Under Climate Change Models

Future Distribution of Suitable Habitat for Pelagic Sharks in Australia Under Climate Change Models

Spatially explicit risk assessment of marine megafauna vulnerability to Indian Ocean tuna fisheries

Evaluation of Shifts in the Potential Future Distributions of Carcharhinid Sharks Under Different Climate Change Scenarios

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