Evaluating Biological Stock Structure of Atlantic Cod to Inform Industry Fishery Management

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Project Type: 
Research
Project Number: 
R/SFA-3
Inception Date: 
2016
Completion Date: 
2018

Participants:

Erik Chapman N.H. Sea Grant Co-Principal Investigator
Steven Cadrin University of Massachusetts - Dartmouth Collaborator
Lisa Kerr Gulf of Maine Research Institute Collaborator
Adrienne Kovach UNH - Department of Natural Resources & the Environment Principal Investigator
Abstract: 

One of the most economically and culturally important commercial fish in the North Atlantic, Atlantic cod (Gadus morhua) populations today are at a small fraction of their carrying capacity, and fishing communities that once depended on them are struggling for their existence. Rebuilding cod stocks is vital to the economies of New England coastal communities, and to restoring a healthy ecosystem. While management has been effective in controlling fishing pressure, cod stocks have suffered in part due to an inadequate understanding of cod population structure and dynamics and poor linkages between science and management. Addressing this problem necessitates reevaluating stock structure and spatial distribution, the basis for management. It also requires working together with fisherman and fisheries managers to achieve consensus on applying the science to effect policy change. These are the goals that we address in this project through interdisciplinary research collaboration, extension and outreach. We will use a state-of-the art population genomic approach to characterize the biological stock structure of Atlantic cod in U.S. and neighboring Canadian waters. Genome-wide data will elucidate fine-scale gene flow and demographic processes in relation to spatial scale. The genomic approach will also yield information on adaptive genetic variation underlying ecologically relevant differentiation. Integration of high-resolution data on demographic and adaptive processes will reveal comprehensive knowledge of population structure to facilitate optimal decision-making. By forming a formal cod stock structure working group, we will synthesize our findings with those of regional scientists studying multidisciplinary aspects of cod stock structure and engage with managers and fishermen to interpret the implications of research results for management. Our efforts will lead to an improved understanding of cod population structure and alternative management strategies that more accurately reflect cod population structure and spatial scale.

Objectives: 

1. To characterize spatial genetic structure and demographic connectivity of all active spawning cod populations in U.S. and neighboring Canadian waters.

2. To identify adaptive genetic variation that may underlie ecological differences among cod populations.

3. To reconstruct the recent historical population structure and stock composition of now depleted population segments of eastern Gulf of Maine cod using archived otolith samples from the 1960s, and to determine if local population structure has been lost through recent declines.

4. To facilitate communication of data collection and analysis with other scientists and projects that are conducting complementary research to improve our understanding of biological structure of Atlantic cod in U.S. waters.

5. To provide fisheries scientists, managers and fishermen with an improved understanding of the biological structure of modern cod stocks, the extent to which they are influenced by local recruitment and adaptive processes, and if/how this structure has changed over time.

6. To engage fishermen, fisheries scientists and managers in discussion about cod stock structure and its implications, identify barriers and opportunities for using the current understanding of structure to adjust groundfish management strategy, and collectively identify a set of management alternatives.

Methodology: 

Biological stock structure of Atlantic cod in U.S. and adjacent Canadian waters will be characterized using a population genomics approach that identifies both fine-scale gene flow and spatial structure reflective of demographic processes and adaptive variation indicative of underlying ecological differentiation. Findings of this study will be synthesized with those of regional scientists studying multidisciplinary aspects of cod stock structure to form a comprehensive understanding of cod population structure. A working group comprised of researchers, managers, fisherman and fisheries scientists will be formed to synthesize the best available science and achieve consensus on its interpretation for management. Through a workshop attended by these diverse stockholders, a set of management alternatives will be developed that reflect the improved understanding of cod stock structure. Outreach efforts will engage fisherman through meetings with Sector Fisherman Groups and multiple educational venues will be used to reach college students and the general public and provide increased awareness about the project results and the importance of population resilience in fishery management and ecosystem science in general.

Rationale: 

U.S. Atlantic cod (Gadus morhua) populations today are at a small fraction of their carrying capacity, and fishing communities that once depended on them are struggling for their existence. Cod stocks currently are at <5% of target levels in the Gulf of Maine and Georges Bank, and the latest Cod Stock Assessment finds spawning stock biomass to be the lowest ever estimated, generating grave concern among fishermen for their livelihoods and among managers for the poor condition of cod stocks. The collapse of the Atlantic cod fishery and resulting economic hardships may be due in part to an inadequate understanding of cod population structure and dynamics and poor linkages between science and management. Biological knowledge of local populations is necessary for appropriate fisheries management and recovery of depleted stocks. Aligning management boundaries with the spatial boundaries of sub-populations increases potential for stock recovery, while misalignment of these boundaries may exacerbate declines. Identifying biologically relevant stock boundaries, therefore, is an important goal of fisheries science. Working together with fishermen and fisheries managers is also necessary to achieve consensus on applying the science to effect policy change. These goals are addressed in this project through interdisciplinary research, extension and outreach. By filling key knowledge gaps in cod stock structure and transferring these results to fisheries managers, this project will provide information necessary for reevaluating fisheries assessment and management. Synthesis of our findings with those of other regional scientists studying Atlantic cod stocks will provide a framework for developing management alternatives that recognize the importance of stock complexity in population resilience, and of spatial scale to sustainable management. Direct integration of fisheries scientists, fishermen, and managers into our project through a formal working group and collaborative workshop will facilitate consensus building around management implications and ensure the results are used to improve the management of cod. Rebuilding cod stocks is vital to the economies of New England coastal communities, and to restoring a healthy ecosystem.