The troubled future of Atlantic cod is murkier than ever as science reveals a myriad of behaviors in this iconic fish, making it more daunting to say when and where it should be caught. “We’re almost overwhelmed with complexity,” said Tom Nies, groundfish analyst for the New England Fishery Management Council. “We still have vast areas that have not been sampled, vast areas where we don’t know what’s happening.”
The complexity was clarified last week at a scientific conference convened by the council and the Gulf of Maine Research Institute. The conference was held in the wake of the discovery earlier this year that cod were not recovering as hoped for in the Gulf of Maine under a 10-year-plan to reestablish stocks by 2014. Fishermen are currently operating under a 22-percent cut in their allowable catch, and likely face a far more dramatic cut next year from the National Oceanic and Atmospheric Administration.
Scientists say the emerging problem in assessing future catches is not only the raw numbers of cod being caught. It is also that cod have more genetic substocks than once thought, meaning that decimation of any one substock could dramatically alter the reproductive ability of the whole stock. Also, studies of tagged cod show that a fair amount of fish move back and forth between the Bay of Fundy and Georges Bank and between inshore Gulf of Maine waters and Cape Cod waters. Tagging researcher Shelly Tallack said, “This connectivity really makes it difficult to interpret what you’re seeing at any one time.”
Other research of tagged cod suggests that some subpopulations have an amazing homing instinct for spawning sites, given the vastness of the ocean. UMass Dartmouth researcher Douglas Zemeckis is documenting multi-year fidelity of cod to their spawning sites and finding that they can return to within 100 meters of the site.
The magnitude of that finding was amplified by Ted Ames, co-founder of the Penobscot East Resource Center and a MacArthur Fellow for his research as a commercial fisherman. In 2004, Ames found that nearly half of of the Gulf of Maine’s spawning grounds of the early 20th century were inactive, a likely combination of overfishing, coastal pollution, and dams that prevented the reproduction of food for cod such as alewife and herring. “We’ve eliminated the prey base,” Ames said.
The research on spawning was so impressive that Tim Tower, who operates a charter fishing boat out of Ogunquit, said, “The biggest thing to me is to protect the big, spawning fish.” David Goethel, a commercial fisherman out of Hampton, N.H., who takes researchers out for cod tagging, said, “These facts about natal homing are critical. If we take too many of those fish, there will be no one to lead the way back.”
That does not even factor in climate change, which researchers said may warm or cool various layers of the ocean, driving cod away from food or into new areas to be overfished.
In announcing its cod catch cuts in April, NOAA said it would reassess stocks before issuing catch limits for 2013. Judging from the data being presented, there is little to be optimistic about in the short term. Most of the five dozen participants felt management boundaries needed to be changed, with an acute focus on spawning sites, but more research is needed to figure out how.
“What shouldn’t get lost in all this,” said Mike Palmer of NOAA’s Northeast Fisheries Science Center in Woods Hole, “is that we were seeing rebuilding in cod stocks, just not as much as we wanted. Cod is a resilient fish over long expanses of time. They were here before the glaciers. We have to see if we can find a management system that still gives them more time.”
Going by the data, cod may need even more time than scientists once believed.
Derrick Z. Jackson can be reached at email@example.com.