The northwest Atlantic cod fishery is arguably one of the best-known and most historically important fisheries in the world. That importance made the collapse of the region’s cod stocks all the more noteworthy, and adds a degree of urgency to ongoing efforts to return such stocks to health.
Unfortunately, biologists have found cod slow to respond to management measures. Canada imposed a moratorium on the Newfoundland cod fishery in 1992; twenty-five years later, the stocks are finally beginning to recover.
Off the coast of New England, cod stocks still languish at or near their historic lows, despite managers’ efforts to rebuild them. One of the reasons for such a stubborn decline may be that the current management units, which define all cod off the northeastern United States as belonging to either the Gulf of Maine or the Georges Bank stock, oversimplifies the population structure. Instead of there being just two large stocks of fish that share similar biological characteristics, research suggests that there may instead be many smaller, local spawning populations.
Such a complex population structure would help to explain why current management measures have not been more effective, as management measures which are likely to be successful when applied to a large, unitary population fail when the vulnerabilities of small, local populations are not taken into account. Annual catch limits that appear conservative when applied to one of the two currently recognized stocks could still be high enough to cause such local spawning populations to collapse; historical records indicate that populations that once spawned just off the coast of Maine may already have been seriously depleted in the 1940s.
Such local depletion becomes even more significant in the face of research that suggests that once a spawning area has lost its resident cod population, fish from adjacent spawning areas do not move in to repopulate the site. Instead, it remains barren.
Thus, it is important that the governments of the United States and Canada have recently created the Atlantic Cod Stock Structure Working Group (Working Group), which will endeavor to identify each local population on a biological and ecological basis. Its aim is to bring together scientists from government, academia and non-governmental organizations who have been studying such local populations, and provide an environment in which they can more easily collaborate and coordinate their research. The international nature of the Working Group will make it easier for it to study and define populations that straddle international boundaries.
The Working Group held its first meeting in February 2018; it is scheduled to continue its work for two years. We will keep you informed of any findings that it may release along the way.