Relative Impacts of Simultaneous Stressors on a Pelagic Marine Ecosystem

Abstract

Climate change and fishing are two of the greatest anthropogenic stressors on marine ecosystems. We investigate the effects of these stressors on Hawaii's deep-set longline fishery for bigeye tuna (Thunnus obesus) and the ecosystem which supports it using a size-based food web model that incorporates individual species and captures the metabolic effects of rising ocean temperatures. We find that when fishing and climate change are examined individually, fishing is the greater stressor. This suggests that proactive fisheries management could be a particularly effective tool for mitigating anthropogenic stressors either by balancing or outweighing climate effects. However, modeling these stressors jointly shows that even large management changes cannot completely offset climate effects. Our results suggest that a decline in Hawaii's longline fishery yield may be inevitable. The effect of climate change on the ecosystem depends primarily upon the intensity of fishing mortality. Management measures which take this into account can both minimize fishery decline and support at least some level of ecosystem resilience.

Ensemble Projections of Future Climate Change Impacts on the Eastern Bering Sea Food Web Using a Multispecies Size Spectrum Model

“…That said, in the absence of detailed species-specific information, the model set could also be expanded to represent other general but more nuanced hypotheses regarding temperature effects. For instance, the scaling of temperature-dependencies may change with ontogeny (Lindmark et al, 2018), differ across biological rates (Englund et al, 2011;Rall et al, 2012), or scale with temperature in a manner different from that described by the Arrhenius correction factor (Woodworth-Jefcoats et al, 2019). The latter may occur if species are currently at or near their thermal maximum.…”

“…The latter may occur if species are currently at or near their thermal maximum. If so, additional warming could reduce rates ultimately controlling body growth, for example (Woodworth-Jefcoats et al, 2019). In the EBS, this issue may emerge for some species, particularly those with restricted northern distributions (e.g.…”

“…This latter feature makes multispecies size spectrum models (MSSMs) strong candidates for evaluating climate impacts because the hypothesized effects of climate variables (e.g. temperature) on animal energy budgets can be modeled in a more mechanistic fashion and scaled up to the population and community levels (Maury and Poggiale, 2013;Lefort et al, 2015;Guiet et al, 2016;Woodworth-Jefcoats et al, 2019).…”

Complex Dispersal of Adult Yellowfin Tuna From the Main Hawaiian Islands

“…The contrasting movement patterns exhibited by different yellowfin life stages and studies conducted over a decade apart have demonstrated that tuna movement between tropical and temperate regions remains inadequately understood (Holland et al, 1999;Pecoraro et al, 2017Pecoraro et al, , 2018Anderson et al, 2019). As the Central North Pacific faces various anthropogenic stressors (Erauskin-Extramiana et al, 2019;Woodworth-Jefcoats et al, 2019) and stakeholders experience potential changes to fisheries management and conservation measures such as creation of large-scale marine protected areas (Richardson et al, 2018;Hernández et al, 2019), availability of yellowfin tuna and economic impacts to local communities will remain a serious issue.…”

Contrasting Futures for Australia’s Fisheries Stocks Under IPCC RCP8.5 Emissions – A Multi-Ecosystem Model Approach

“…different diet compositions) and various scenarios (including a greater suite of climate drivers, potential human impact effects, and socioeconomic characteristics). For example, development of multispecies and trait-based size spectrum models for use in climate projections (Woodworth-Jefcoats et al, 2019) has focused on testing the effects of alternative climate processes and mechanisms as well as the use of statistical models to quantify their contribution toward uncertainty (Reum et al, 2020). Such advances, in addition to those discussed above, will provide more confidence in the robustness of individual, multiple and ensemble ecosystem model projections of the future.…”