The Integrity of a Stratified Random Stock Survey Design in Light of Projected Climate-Induced Changes in Species Distribution: The Case of the Atlantic Surfclam, Spisula Solidissima, Over the Remainder of the 21st Century

Abstract

The distribution of the commercially important Atlantic surfclam, Spisula solidissima, is projected to expand offshore as ocean warming continues, extending this species into what has historically been a cold-water habitat occupied by the ocean quahog, Arctica islandica. This anticipated range shift prompts an investigation into the resiliency of the Atlantic surfclam survey design over the remainder of the 21st century. To our knowledge, this is the first evaluation of the resiliency of a stratified random survey design in anticipation of shifts in a stock’s geographic range. Simulations of survey performance show that the Atlantic surfclam survey provides reliable estimates of biomass over the remainder of the 21st century, with bias generally decreasing over time. Improvement in survey performance accrues from the influence of warming temperatures on geographic distribution, where a reduction in large-scale patchiness is predicted as surfclams disperse more evenly across the shelf over coming decades. However, the survey eventually fails to capture the entirety of the Atlantic surfclam stock, as an increasing number of clams occupy areas outside of the survey domain.

Keywords: Survey design, Climate change, Atlantic Surfclam, Commercial Fisheries, Stock Assessment