Threats to menhaden are exaggerated

The status of the menhaden fishery is much less dire than depicted

Dave Shirley’s op-ed (“Why should we care about the menhaden,” Nov. 30-Dec. 13 NHBR) repeats several familiar claims about the menhaden fishery. Unfortunately, most of these claims are misleading, presenting half-truths and rhetoric instead of a balanced account of the facts.

For example, Mr. Shirley begins his piece claiming, “the menhaden population has plummeted 90 percent over the past 25 years.” This is, at best, an incomplete statistic. While Mr. Shirley is correct that the menhaden population has declined from a relative high in the early 1980s, his claim is still misleading because it does not examine all of the available data collected over the past 50 years by the Atlantic States Marine Fisheries Commission (ASMFC).

This data shows that menhaden biomass depends on the strength of menhaden recruitment (the number of menhaden that are born), which varies from year to year and is influenced by a number of factors, perhaps most importantly environmental conditions. For example, the early 1980s was a period of strong menhaden recruitment influenced by favorable environmental conditions, which led to high biomass. Since then, environmental conditions have been much less favorable, resulting in lower recruitment and a smaller population.

The decline that Mr. Shirley cites is part of this natural variation, as the current size of the menhaden population is similar to the size of the population in the late 1960s.

That environmental factors are perhaps the strongest influence on menhaden recruitment is recognized by both the ASMFC, which concluded in its 2010 stock assessment that fluctuations in menhaden abundance may be, “almost entirely driven by non-fishery sources.”

Similarly incomplete is Mr. Shirley’s assertion that overfishing of menhaden “has occurred 32 of the last 54 years.” But not mentioned is that overfishing (where the fishery exceeds mortality limits set by the ASMFC) has become an increasingly rare occurrence in the fishery: Out of the 32 years overfishing was recorded, only two of them occurred in the last 15 years for which reliable data is available (1993-2008).

The stock is also not overfished, meaning that it is producing enough eggs to sustain itself.

Mr. Shirley also writes “in the Chesapeake Bay, the percentage of menhaden in the diets of many recreational fish such as striped bass and weakfish has fallen from double to single digits in the last decade. Today many striped bass show signs of malnutrition and poor health.” But striped bass are not as dependent on menhaden as Mr. Shirley implies.

Bass are opportunistic predators, who consume a variety of prey species depending on their availability and location; bay anchovies, small crustaceans, and worms are all significant parts of the striped bass diet in addition to menhaden. Because bass diets are so variable, it is unlikely that they are dependent on any single food source for survival.

Ultimately, the status of menhaden is much less dire than Mr. Shirley’s article indicates. While Mr. Shirley advocates for a 50 percent reduction in the commercial menhaden catch, based on all the available evidence a much less precipitous cut is more likely needed.

John Shafmaster
Little Bay Lobster

Categories: Opinion