The power of fishy old ideas

Never underestimate the appeal of a simple idea.

This splendid photograph of Atlantic herring comes from
http://www.gma.org/herring/

The New York Times reports this week on an unusual alliance between small boat fishermen and environmentalists, joining forces against the larger boats that catch approximately 98 percent of the 100,000 tons of herring taken each year off New England.  The big boat captain argues that that herring are most abundant species in the area and “to keep the ecosystem in balance, somebody has to harvest them.” In other words, fishing plays a vital role in sustaining fish populations.

A lot of people thought this—back in 1949. One of them was a University of Washington ichthyologist, Wilbert McLeod Chapman, whose ideas about fish and fishing powerfully shaped fisheries science in this country.

The years following World War II were difficult for New England fishermen. They were plagued by cheap imported fish from Canada. Traditional fisheries were depleted and they had to fish further from home. They sought relief from the fish imports, but American trade policy was moving towards open markets.

The fishing industry sought to influence State Department policy over tariffs and a sympathetic George C. Marshall agreed to appoint a fisheries attaché. The Department wanted an attorney, but the industry wanted Chapman. Within months of arriving in Washington, he announced the U.S. Policy on High Seas Fisheries, published in the State Department Bulletin in January of 1949.  Chapman believed that if fish weren’t harvested, they were wasted. They matured, died, and benefited no one.

But as the small-boat captains and the environmentalists in the Times article point out, herring are basis of the food chain, not only for other fish, but for mammals and sea birds. If too many herring are caught, the impacts will ripple throughout the entire ecosystem.

At the heart of Chapman’s version of fishery science in 1949 is the idea that removing larger, older fish freed up food for faster-growing small fish. Fishing produced the conditions that allowed the population to respond and produce the maximum number of fish on a sustained basis, year after year. Human intervention played an integral role in stabilizing fish populations and allowing the fish to gain maximum weight, when they would be removed. Thinning out the old population through intense fishing replaced the old, slow-growing fish with younger, fast-growing individuals, increasing the weight of the crop, just as thinning trees increased the yield in a forest.

It took a long time for scientists to gather the data to prove that Chapman’s construction was way too simple. The technology to catch fish spread with enormous rapidly after World War II, fueled by government money that built boats to meet a variety of domestic and foreign policy objectives.

But understanding the structure of fish populations was as much more subtle and difficult. Fishermen began fishing in deep-water, beyond 100 fathoms, for redfish (Sebastes spp.)  in the 1930s; it took until 1980 for scientists to craft the tools to property age these medium-sized, bright red fish. Many stocks were depleted by the time scientists determined the fish could live for decades, far longer than originally assumed.

Other information came still later, like the importance of old females, that provide larger, more viable eggs, especially important in carrying a population through years of poor spawning conditions. Sub-populations lend stability, helping withstand disturbances, such as shifts in currents, temperatures, and food supply. Ecologists call this resilience and see it as the key to sustaining fish populations in the future.

The small boat fishermen in The New York Times story are wary about climbing into bed with the environmentalists and opposing how fellow fishermen catch their share of the fish. But if we’re going to sustain fish populations, we have to discard what we thought was right in 1949, and shift our focus from just harvesting masses of fish, to stabilizing the ecosystems that we—and the fish—both depend on. And it’s going to take new alliances to do it, especially between old enemies.

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About finleyc

I'm a writer and a historian of science. I'm interested in the intersection of science and policy in the oceans, and especially around fishing.
This entry was posted in Environmental History, Fisheries policy, Fishing, History of Science, Marine Policy, Ocean fishing, Pacific Fishing History Project, Rosefish, Sebastes rockfish and tagged , , , , , , , . Bookmark the permalink.

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