Species redistribution creates unequal outcomes for multispecies fisheries under projected climate change

Abstract

Climate change drives species distribution shifts, affecting the availability of resources people rely upon for food and livelihoods. These impacts are complex, manifest at local scales, and have diverse effects across multiple species. However, for wild capture fisheries, current understanding is dominated by predictions for individual species at coarse spatial scales. We show that species-specific responses to localized environmental changes will alter the collection of co-occurring species within established fishing footprints along the U.S. West Coast. We demonstrate that availability of the most economically valuable, primary target species is highly likely to decline coastwide in response to warming and reduced oxygen concentrations, while availability of the most abundant, secondary target species will potentially increase. A spatial reshuffling of primary and secondary target species suggests regionally heterogeneous opportunities for fishers to adapt by changing where or what they fish. Developing foresight into the collective responses of species at local scales will enable more effective and tangible adaptation pathways for fishing communities.

Fig. 1.. Coastwide projections of bottom temperature, bottom oxygen, and species abundance.

(A) Projected coast-wide change in bottom temperature (°C) and bottom oxygen (mmol/m³), comparing the 2075–2100 mean to the 1985–2010 baseline period and presented as an ensemble mean across the three CCROMS-ESMs. (B) Projected ensemble abundance indices for the four DTS species under the three CCROMS-ESMs, presented as 5-year running averages. Solid lines are median projection values, and ribbons display ±1 SE. Black vertical bars denote the range of historical variability in the abundance index for each species from 1985 to 2010.

Fig. 2.. Projected changes in DTS species’ distance from shore and depth distributions.

(A) Projected change in the weighted distance from shore centroid of species’ distributions, comparing the 2075–2100 mean to the 1985–2010 baseline period. Values to the left and right of the dashed vertical line at 0 indicate species whose distributions are expected to shift onshore and offshore, respectively. Individual points indicate values from one simulation of the 100 performed for each species and CCROMS-ESM projection (panels). Lines are locally estimated scatterplot smooths. (B) Projected changes in depth distribution for each species, displayed as the proportion of summed catch in areas shallower than 700 fathoms, the current depth limit of allowable bottom trawling. Points and lines are as described in (A).

Fig. 3.. Projected environmental change within fishing footprints.

(A) Trawl fishing footprints of major U.S. West Coast ports targeting DTS species. Projected change in (B) mean bottom oxygen (mmol/m³) and (C) mean bottom temperature (°C) coastwide and within specific fishing footprints, based on an ensemble mean across the three CCROMS-ESMs. Arrows represent change from a 1985–2010 mean to a 2075–2100 mean. (D) Empirical environmental niches of DTS species. Outlines encompass the 75th percentile of each species’ estimated biomass density values from 1985 to 2010 in environmental state space. Arrows indicate the same climate changes as (B) and (C) within fishing footprints.

Fig. 4.. Changes in Dover sole and sablefish biomass density and overlap.

(A) Projected percent change in density from a 1985–2010 mean to a 2075–2100 mean for sablefish and Dover sole in the Astoria and Fort Bragg fishing areas, under alternative CCROMS-ESMs projections. (B) Change in spatial overlap between sablefish and Dover sole within the same footprints and time periods, measured by the Bhattacharyya’s coefficient. Points below the dashed line at zero represent reduced overlap in future projections compared to the historical mean. Error bars represent the distribution of change in overlap across the 100 draws from the joint parameter distribution for each species and CCROMS-ESM projection.