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SSMU-specific outcomes of FBM-Krill for predators and the fishery under a modeled climate change impact. Projected penguin (A, B) and seal (C, D) abundances, and krill catches (E, F) given climate-change impacts on krill growth, with outcomes at 30 years in to the model run in the left column (A, C, E) and at 100 years in the right (B, D, F). Blues represent increases relative to the No FBM base case scenario and reds decreases; white and light colors indicate no or little change. Light grey denotes areas where the species group is not modeled as resident. Note changes are relative to the No FBM base case within each SSMU, not over the entire model arena. https://doi.org/10.1371/journal.pone.0231954.g004
Source publication
To implement ecosystem-based approaches to fisheries management, decision makers need insight on the potential costs and benefits of the policy options available to them. In the Southern Ocean, two such options for addressing trade-offs between krill-dependent predators and the krill fishery include "feedback management" (FBM) strategies and marine...
Contexts in source publication
Context 1
... the smaller SSMU spatial scale, our model projected the relative abundances of krill predators to vary spatially and across scenarios (due to the large number of results, we have projected outcomes as maps, with results available in the S1 Data). FBM-Krill generally provided slight benefits to penguins and seals in several SSMUs (Fig 4A-4D), but outcomes from FBM-Pengs were more mixed, with relative abundances increasing in some SSMUs and decreasing in others (Fig 5A-5D). While there were only slight difference in SSMU-specific outcomes from FBM-Krill after 30 and 100 years (Fig 4A-4D), we projected that FBM-Pengs intensified changes in predator abundance over time (Fig 5A-5D). ...
Context 2
... generally provided slight benefits to penguins and seals in several SSMUs (Fig 4A-4D), but outcomes from FBM-Pengs were more mixed, with relative abundances increasing in some SSMUs and decreasing in others (Fig 5A-5D). While there were only slight difference in SSMU-specific outcomes from FBM-Krill after 30 and 100 years (Fig 4A-4D), we projected that FBM-Pengs intensified changes in predator abundance over time (Fig 5A-5D). With the MPA, variability in the relative abundances of penguins and seals among SSMUs was intermediate to the levels of variability under FBM-Krill and FBM-Pengs, but with greater positive outcomes projected across most SSMUs for penguins (Fig 6A-6D). ...
Context 3
... projected performance of the krill fishery would also vary by SSMU. FBM-Krill resulted in various changes in relative catch, with decreases in most coastal SSMUs in Subarea 48.1 and 48.2, and increases elsewhere (Fig 4E-4F). FBM-Pengs projected even more pronounced changes in relative catch, but, again, decreases were projected in some coastal SSMUS and increases in others (Fig 5E and 5F). ...
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Citations
... almost200 years, fishery studies have focused on the species distributed in the 48 Antarctic Peninsula (Zhu et al., 2020), Weddell (Roche et al., 2019), Ross (Mormede 49 et al., 2020), and Scotia Seas (Collins et al., 2008;Klein and Watters, 2020); however, the Antarctic continental shelf (Collins et al., 2012;Donnelly and Torres, 2008;53 Donnelly et al., 2004;Gon and Heemstra, 1990), has the second-largest fish biomass 54 next to the Antarctic silverfish (Pleuragramma antarctica) in the Cosmonaut Sea and 55 Prydz Bay( Van de Putte et al., 2010). Adult N. coatsorum individuals live from0-4 habitat suitability and future habitat changes of N. coatsorum in the Southern Ocean. ...
The Southern Ocean faces many challenges under global climate change. Species distribution models (SDMs) are considered a powerful tool for predicting the potential distributions of species when evaluating the effects of climate change. We employed a partially area-under-the-curve (AUC)-based ensemble model to predict the current habitat suitability and future habitat changes of N. coatsorum in the Southern Ocean. The SDMs developed included six different predictors that contribute to the N. coatsorum distribution: depth accounted for the highest contribution of 33.8%, closely followed by the sea surface temperature (30.3% contribution). The contributions of the sea surface salinity distance from land, sea ice thickness and current velocity were 12.7%, 12.3%, 8.1%, and 2.8%, respectively. N. coatsorum has a suitable distribution area of approximately 5.63 million km² under current conditions, comprising29.8% of the Southern Ocean area. A significant expected decrease(43.0%) at the species’ northward edges, especially on the southeast Antarctic coast, may occur in the future as suggested by comparing the current model range to the suitable habitat changes predicted in 2100 under the RCP8.5 scenario, resulting in the formation of three newly gained or remaining climate refugia for N. coatsorum: areas close to the Ronne and Filchner Ice Shelves in the Weddell Sea, the Ross Sea, and along the coast of northeastern Antarctica (including in the Cosmonaut Sea and Prydz Bay). Our ensemble approach for assessing the habitat features of N. coatsorum allows the impacts of climate change on a mesopelagic fish species in the Southern Ocean to be assessed.
Global targets for area-based conservation and management must move beyond threshold-based targets alone and must account for the quality of such areas. In the Southern Ocean around Antarctica, a region where key biodiversity faces unprecedented risks from climate change and where there is a growing demand to extract resources, a number of marine areas have been afforded enhanced conservation or management measures through two adopted marine protected areas (MPAs). However, evidence suggests that additional high quality areas could benefit from a proposed network of MPAs. Penguins offer a particular opportunity to identify high quality areas because these birds, as highly visible central-place foragers, are considered indicator species whose populations reflect the state of the surrounding marine environment. We compiled a comprehensive dataset of the location of penguin colonies and their associated abundance estimates in Antarctica. We then estimated the at-sea distribution of birds based on information derived from tracking data and through the application of a modified foraging radius approach with a density decay function to identify some of the most important marine areas for chick-rearing adult penguins throughout waters surrounding Antarctica following the Important Bird and Biodiversity Area (IBA) framework. Additionally, we assessed how marine IBAs overlapped with the currently adopted and proposed network of key management areas (primarily MPAs), and how the krill fishery likely overlapped with marine IBAs over the past five decades. We identified 63 marine IBAs throughout Antarctic waters and found that were the proposed MPAs to be adopted, the permanent conservation of high quality areas for penguin species would increase by between 49 and 100% depending on the species. Furthermore, our data show that, despite a generally contracting range of operation by the krill fishery in Antarctica over the past five decades, a consistently disproportionate amount of krill is being harvested within marine IBAs compared to the total area in which the fishery operates. Our results support the designation of the proposed MPA network and offer additional guidance as to where decision-makers should act before further perturbation occurs in the Antarctic marine ecosystem.
