Aquaculture 2025

March 6 - 10, 2025

New Orleans, Louisiana USA

Add To Calendar 07/03/2025 13:45:0007/03/2025 14:05:00America/ChicagoAquaculture 2025EVALUATING THE INTEGRITY OF A STRATIFIED RANDOM STOCK SURVEY DESIGN IN LIGHT OF PROJECTED CLIMATE-INDUCED CHANGES IN SPECIES DISTRIBUTIONS: AN ATLANTIC SURFCLAM CASE STUDYStudio 8The World Aquaculture Societyjohnc@was.orgfalseDD/MM/YYYYanrl65yqlzh3g1q0dme13067

EVALUATING THE INTEGRITY OF A STRATIFIED RANDOM STOCK SURVEY DESIGN IN LIGHT OF PROJECTED CLIMATE-INDUCED CHANGES IN SPECIES DISTRIBUTIONS: AN ATLANTIC SURFCLAM CASE STUDY

Molly Spencer*1, Dan Hennen2, Eric Powell1

1University of Southern Mississippi, Gulf Coast Research Laboratory, 703 East Beach Dr., Ocean Springs, MS 39564

2Northeast Fisheries Science Center, NMFS, NOAA, Woods Hole, MA, United States

 



Instances of range expansion and poleward shifts in species continue to occur on the Northeast Continental Shelf due to climate-induced warming. Changes in the distribution of commercial species has severe implications for fisheries stock assessments, as changes in species’ distributions outpace revisions in stock survey designs, therefore increasing uncertainty in stock biomass estimates. The distribution of the commercially important Atlantic surfclam, Spisula solidissima, a biomass dominant on the Mid-Atlantic Bight shelf, has been projected to expand offshore and north as shelf warming continues, landing this species into what has historically been a cold-water habitat for the commercially important ocean quahog, Arctica islandica. This anticipated range shift prompts an investigation into the statistical strength of the Atlantic surfclam federal survey design over the remainder of the 21st century. The survey is organized into 4 parts: the inshore and offshore regions of the MAB west of the Great South Channel, and the periphery and interior of Georges Bank. Anticipated outcomes of this distributional shift among these four units include a degradation in the integrity of the stratified random sampling regime as the stock redistributes itself, leading to decreased confidence in status of stock estimates. This is particularly true for the two offshore regions for which stratum design and sample density were originally developed to optimize biomass estimates of the colder-water ocean quahog, a species being displaced over time by the Atlantic surfclam. Results of this investigation show that the Atlantic surfclam survey in all four regions provides reliable estimates of biomass over a 79-year period, with bias generally decreasing over time. This perhaps unexpected improvement in survey performance accrues from the influence of warming temperatures on geographic distribution, where a reduction in large-scale patchiness is observed as clams disperse more evenly across the shelf over the coming decades. However, the survey becomes increasingly incapable of capturing the entirety of the Atlantic surfclam biological habitat over time, as an increasing number of clams occupy areas outside of the survey boundaries, with the worst mismatch occurring in the early 2080s when approximately 12% of total surfclam biomass will be missing from the survey.