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

Abstract

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.

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

“…Regarding changes in environmental variables and shifts in range, in our study, temperature range, and other variables related to temperature, made the highest contributions to the niche models. This supports the findings of other studies on shark distributions (Lezama-Ochoa et al, 2016;Birkmanis et al, 2020). Being ectothermic organisms, in common with other teleost fishes, the physiological functions of many sharks are controlled and determined by temperature and their thermal tolerance limits.…”

“…Some studies of shark species in particular have described potential changes in their distribution in response to projected changes in climate, which are related to the reduced or increased availability of suitable habitat and poleward shifts in their distribution (Hare et al, 2016;Tanaka et al, 2021). Other studies have evaluated the potential distribution of carcharhinid sharks with climate change using species distribution modeling and generally report a reduction or shift in suitable area for future distributions under different climate change scenarios (Jones et al, 2013;Lezama-Ochoa et al, 2016;Gonzalez-Pestana, 2018;Birkmanis et al, 2020;Crear et al, 2020).…”

Elasmobranch Responses to Experimental Warming, Acidification, and Oxygen Loss—A Meta-Analysis

“…As such, the identification of knowledge gaps, along with the targeted focus toward the most pressing concerns, is particularly critical for this group. On the other hand, while experimental research provides a central stepping-stone to understand the impacts of climate change over this taxon, it is crucial that we further integrate these insights with the information collected through different approaches (e.g., Chin et al, 2010;O'Brien et al, 2013;Lighten et al, 2016;Birkmanis et al, 2020;Vedor et al, 2021).…”

Habitat model forecasts suggest potential redistribution of marine predators in the southern Indian Ocean

“…Araújo & Luoto, 2007;Gilman et al, 2010). However, Erauskin-Extramiana et al (2019) used fishing records to forecast the worldwide, end-of-century distributions of six tuna species while Birkmanis et al (2020) used catch records for seven shark species in Australian waters to forecast their future distributions (see also Hobday, 2010). Some studies have used multi-species animal tracking data sets for this purpose.…”