Creating and evaluating indices of climate-induced changes in spatial distributions of North Pacific fishery resources

Malin Pinsky, Rutgers University

Abstract

A primary step in accounting for climate change in fisheries management is to develop

robust indices of long-term climate change effects on the distribution and biomass of

commercially harvested species. Accounting for climate-associated changes in the spatial

distribution of commercially harvested species is of high priority because such shifts can

complicate accurate assessment of stock status. Indicators of species-specific spatial shifts in

distributions could inform these stock assessments, but are currently lacking. In addition, most

projections of species distributional shifts in response to climate change consider the thermal

tolerances of each species in isolation. However, if trophic dynamics depend on temperature

either through changes in prey or predator biomass or predator-prey overlap, this can modify the

response of the species from what would be predicted from temperature alone.

Our analysis will focus on the effects of climate on North Pacific fishery resources.

Ultimately projecting the impacts of climate change on fishery resources in the northeast Pacific

will require evaluations that consider how spatial distributions and abundance of managed

populations are directly affected by temperature, sea level, and coastal transport and indirectly

affected by climate-associated changes in their trophic dynamics. Such analyses are needed to

highlight where shifts associated with climate will be the most dramatic and likely drive the

greatest changes to species and fisheries. Our proposal aims to address these needs by achieving

the following objectives:

(1) Evaluate the degree to which spatial shifts in distributions are related to variability in abiotic

conditions and fishing pressure across the North Pacific.

(2) Create an index of predator-prey overlap, and evaluate how much additional variability in

spatial shifts in distributions is explained by climate-driven changes in predator-prey overlap.

(3) Develop and index of stock availability to US fisheries based on historical changes in

distribution

(4) Predict how future climate change will affect species distributions and predator-prey overlap,

and availability to fisheries.

Specifically, this proposal directly responds to FATE research priority #3 by developing

indices of climate distributional shifts, predator-prey overlap, and availability to fisheries for key

species. Indicators play a critical role in assessing status, trends, and even reference points for

Integrated Ecosystem Assessments (IEAs), and these products will directly inform the

Ecosystem Integrity and Risk sections of the IEA for the three regions. Furthermore, the

indicators from this project would provide a critical step towards proactively identifying species

most at risk from climate change and providing a time-series of shifts in distribution, predatorprey

overlap, and availability to fisheries for use in stock assessment and management. These

will also inform regional, national and international Climate Assessments (project personnel

include members and leads of regional and national climate assessment teams). In addition, this

approach will provide a temporally explicit index to assess which species are moving out of or

are transitory in each region and could be excluded from future FMPs while also identifying

species that are expanding into the region and may require addition to FMPs.