December 21, 2015 — With cod at historically low population levels and commercial fishermen limited to landings that are just a fraction of what they once were, the recreational catch is now believed to account for as much as one-third of total landings of Gulf of Maine cod.
But recreational landings data was considerably poorer than the commercial data, which made it hard to estimate their true impact on the population or know the effectiveness of regulatory measures.
Solving the cod crisis will take a lot of research. Now, scientists are no longer restricted to their lab. As a recent study shows, creative thinking and technology can turn the ocean into a lab, and the results can be more precise and minimize the regulatory impact on fishermen.
A key missing piece in the puzzle was information on how many fish died after they were released by anglers. Lacking key data such as length and weight of released cod resulted in the assumption that 100 percent of those fish died. Missing data can lead to underestimating the population size, with overly strict regulations, said Michael Palmer, National Marine Fisheries Service research fishery biologist.
Researchers started collecting length and weight data in 2005 after regulators tightened reporting requirements for recreational fishermen. In 2011, a panel arrived at a consensus that 30 percent of cod released by anglers died. But Palmer was concerned that there were no directed studies, in the U.S. or internationally, to truth-test the estimate.
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