Second study links cod comeback to environment
While North Atlantic cod has been in decline for years – and the Gulf of Maine cod stock is currently experiencing the same dilemma – a second study published in October 2015 documents North Atlantic cod’s recovery, and suggests overfishing alone is not to blame.
The study, led by Dr. George Rose with the Centre for Fisheries Ecosystems Research, Fisheries and Marine Institute, Memorial University of Newfoundland in St. John’s, was published in the Canadian Journal of Fisheries and Aquatic Sciences. Rose profiles the “remarkable” comeback of cod in Newfoundland and Labrador, writing that cod biomass in the Bonavista Corridor has increased from a few thousand tons in 2007 to more than 200,000 tons today.
In addition to abundance, the size and condition of the biomass have improved. “The northern cod is making a remarkable comeback from commercial extinction, with production increasing rapidly since 2007 for the first time in nearly two decades,” Rose wrote. “One feature of both the decline and the comeback is how quickly such changes can occur. “
While the Northern cod fishery was plagued with criticism on overfishing and mismanagement, the comeback is linked in part to the abundance of capelin, which cod feed on. “Capelin biomass has been strongly correlated with rebounding cod biomass, which supports earlier notions that northern cod could not rebuild without them,” Rose wrote.
The study is an example of how governments and NGOs claim that overfishing is the problem of reduced fish supply, when that may not be the issue, researchers say. “Cod has been this icon of fisheries that collapse but don’t come back. Yes it was certainly overfished, but the collapse wasn’t due as much to the overfishing,” Ray Hilborn, professor in the School of Aquatic and Fishery Sciences at the University of Washington in Seattle, told SeafoodSource.
Steve Cadrin (pictured), professor in the Department of Fisheries Oceanography and School for Marine Science & Technology at the University of Massachusetts – Dartmouth, agreed. ”I think the first lesson is that cod and most other fishes have a great capacity for recovery, and eventually can rebuild from depleted conditions,” Cadrin said. “The second lesson is that fishing was not the primary factor of cod productivity. Ten years after closing the fishery, the stock still had not shown any signs of rebuilding. Recovery didn’t begin until environmental conditions were favorable for cod production.”
The report’s findings are similar to another study, also released last month, which suggests that rapid warming of the Atlantic Ocean off the northeast coast of the United States played a role in the collapse of the cod fishery there – not overfishing.
The report, published by the academic journal Science, said cod stocks shrank because waters in the Gulf of Maine warmed 99 percent faster there than anywhere in the world, preventing cod from recovering from even a minimal fishing effort.
As a result, scientific recommendations on cod stock in the Gulf of Maine should be re-assessed, according to Cadrin. “Emergency management actions are permanently changing fishing communities to end overfishing as quickly as possible. The cod resource is not endangered, but the fishing community is, Cadrin said. “The primary reason for slow recovery and continued overfishing of Gulf of Maine cod has been scientific uncertainty and abrupt changes in our perception of the resource. Fishery managers have followed the scientific recommendations, but in retrospect, those recommendations were misleading.”