Utilizing Fishermen's Ecological Knowledge to Map Atlantic Cod Spawning Grounds on Georges Bank and Nantucket Shoals

Rebuilding the Georges Bank stock of Atlantic cod (Gadus morhua) has been much slower than expected due to interactions between scientific uncertainty, environmental influences, and species interactions. An important source of scientific uncertainty is our incomplete understanding of cod population dynamics, including the spatial and temporal distribution of spawning. The objective of this study is to map the fine-scale spawning grounds of cod on Georges Bank and the Nantucket Shoals using fishermen’s ecological knowledge to supplement existing scientific data, which alone is insufficient for meeting this objective. Semi-structured interviews were conducted with 50 retired and active Georges Bank cod fishermen from the U.S. and Canada in order to gather detailed information on spawning locations, seasons, duration, magnitude, fish size, preferred depth, and habitat characteristics. Combining fishermen’s ecological knowledge with data from trawl surveys, fishery observers, and ichthyoplankton sampling has successfully identified many fine-scale spawning grounds distributed throughout Georges Bank and the Nantucket Shoals, with spawning mostly observed from November through June. By providing an improved understanding of cod spawning and population dynamics, results from this study are expected to support rebuilding efforts by informing future research and fishery management plans.