A Vulnerability Assessment of Fish and Invertebrates to Climate Change on the Northeast U.S. Continental Shelf

Climate change and decadal variability are impacting marine fish and invertebrate species worldwide and these impacts will continue for the foreseeable future. Quantitative approaches have been developed to examine climate impacts on productivity, abundance, and distribution of various marine fish and invertebrate species. However, it is difficult to apply these approaches to large numbers of species owing to the lack of mechanistic understanding sufficient for quantitative analyses, as well as the lack of scientific infrastructure to support these more detailed studies. Vulnerability assessments provide a framework for evaluating climate impacts over a broad range of species with existing information. These methods combine the exposure of a species to a stressor (climate change and decadal variability) and the sensitivity of species to the stressor. These two components are then combined to estimate an overall vulnerability. Quantitative data are used when available, but qualitative information and expert opinion are used when quantitative data is lacking. Here we conduct a climate vulnerability assessment on 82 fish and invertebrate species in the Northeast U.S. Shelf including exploited, forage, and protected species. We define climate vulnerability as the extent to which abundance or productivity of a species in the region could be impacted by climate change and decadal variability. We find that the overall climate vulnerability is high to very high for approximately half the species assessed; diadromous and benthic invertebrate species exhibit the greatest vulnerability. In addition, the majority of species included in the assessment have a high potential for a change in distribution in response to projected changes in climate. Negative effects of climate change are expected for approximately half of the species assessed, but some species are expected to be positively affected (e.g., increase in productivity or move into the region). These results will inform research and management activities related to understanding and adapting marine fisheries management and conservation to climate change and decadal variability

Relative importance of population size, fishing pressure and temperature on the spatial distribution of nine Northwest Atlantic groundfish stocks

<div><p>The spatial distribution of nine Northwest Atlantic groundfish stocks was documented using spatial indicators based on Northeast Fisheries Science Center spring and fall bottom trawl survey data, 1963–2016. We then evaluated the relative importance of population size, fishing pressure and bottom temperature on spatial distribution with an information theoretic approach. Northward movement in the spring was generally consistent with prior analyses, whereas changes in depth distribution and area occupancy were not. Only two stocks exhibited the same changes in spatiotemporal distribution in the fall as compared with the spring. Fishing pressure was the most important predictor of the center of gravity (i.e., bivariate mean location of the population) for the majority of stocks in the spring, whereas in the fall this was restricted to the east-west component. Fishing pressure was also the most important predictor of the dispersion around the center of gravity in both spring and fall. In contrast, biomass was the most important predictor of area occupancy for the majority of stocks in both seasons. The relative importance of bottom temperature was ranked highest in the fewest number of cases. This study shows that fishing pressure, in addition to the previously established role of climate, influences the spatial distribution of groundfish in the Northwest Atlantic. More broadly, this study is one of a small but growing body of literature to demonstrate that fishing pressure has an effect on the spatial distribution of marine resources. Future work must consider both fishing pressure and climate when examining mechanisms underlying fish distribution shifts.</p></div

The set of models used to sum Akaike weights.

<p>The set of models used to sum Akaike weights.</p

Northeast Fisheries Science Center bottom trawl survey offshore strata.

<p>Stock strata definitions are shown for Gulf of Maine and Georges Bank cod (upper left), the northern and southern stocks of red hake and silver hake (upper right), Georges Bank and (spring only) Southern New England-Mid Atlantic yellowtail flounder (lower left). Ecoregions used in previous analyses are also shown (lower right). Further details, as well as the stock strata definition for white hake, are provided in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0196583#pone.0196583.s001" target="_blank">S1 Supporting Information</a>.</p

Summary of time series trends in the spatial distribution of nine Northwest Atlantic groundfish stocks.

<p>Summary of time series trends in the spatial distribution of nine Northwest Atlantic groundfish stocks.</p

Maps for the three cases in this study where a significant change in the center of gravity was accompanied by a significant decrease in inertia.

<p>Centers of gravity (left) and inertia (right) for Georges Bank yellowtail flounder at five year intervals in the spring, 1970–2015 (upper), and in the fall, 1965–2015 (middle); and Southern New England-Mid Atlantic yellowtail flounder in the spring, 1970–2015 (lower). Closed Area II and the Hague Line are also shown in the upper and middle panels. Due to the tight grouping of the centers of gravity in the lower left panel the year labels are shown in the inset plot. Year labels for both stocks are truncated where necessary for clarity.</p

Sample sizes (<i>n</i>) for objective 1 (time series analysis of spatial distribution) and objective 2 (relative importance of predictor variables on spatial distribution).

<p>Sample sizes (<i>n</i>) for objective 1 (time series analysis of spatial distribution) and objective 2 (relative importance of predictor variables on spatial distribution).</p