Using Fishermen's Ecological Knowledge to map Atlantic cod spawning grounds on Georges Bank

Abstract

The spawning dynamics of Atlantic cod (Gadus morhua) on Georges Bank and Nantucket Shoals are not well understood. To address this uncertainty, we combined Fishermen's Ecological Knowledge (FEK) with traditional scientific data to develop a more holistic understanding of cod spawning on Georges Bank. Data from historical reports, trawl surveys, fisheries observers, and ichthyoplankton surveys were used to describe the spatial and temporal distribution of cod spawning activity. We also collected FEK regarding cod spawning dynamics through semistructured interviews (n=40). The fishermen had detailed knowledge of the spatial and temporal distribution of cod spawning, and identified persistent fine-scale (i.e. <50 km2) spawning grounds that were often associated with specific habitat features, including spawning grounds that were previously unreported in the scientific literature. The spawning seasons and locations identified by fishermen generally agreed with information from traditional scientific data, but it was evident that seasonal scientific surveys lack the spatial and temporal resolution needed to fully characterize the distribution of cod spawning activity. Our results will help inform management measures designed to promote the rebuilding of Georges Bank cod, and also provide a basis for further investigations of cod spawning dynamics and stock structure.