Menhaden, a tiny fish considered “the most important in the sea,” is making big waves off the Atlantic coast.
The Atlantic States Marine Fisheries Commission (ASMFC), which manages the menhaden, discovered a technical error in how they had been measuring the stocks of the forage fish that showed overfishing had occured in two of the last ten years. In fact, a longer view of the Atlantic menhaden stocks indicated that the small fry had, in fact, been overfished for more than half of the fishing seasons over the last 54 years. (Whoops!)
The ASMFC has been gathering comments through public hearings in preparation for a November meeting in Boston where they could adjust future harvest limits, and ultimately determine the fate of Atlantic menhaden stocks.
Why are menhaden important? They’re filter feeders that swim together in large schools, and it’s believed that each tiny fish can filter phytoplankton from four to six gallons of water per minute. But heavy exploitation of the fishery has meant declining numbers. That’s important when you consider the water quality in areas like the Chesapeake Bay and Long Island Sound, where shrinking numbers of menhaden have coincided with algae blooms, pollution, and dead zones.
Menhaden are also an extraordinarily important link in the food chain. They are feeder fish for larger predatory fish, including sea trout, bluefish, wreckfish, tuna, and most especially, striped bass, whose stocks are suffering from disease (mycobacteriosis) and malnourishment.
So just where have all the menhaden gone?
A whopping 80 percent of the harvest is being taken by Houston-based Omega Protein, which targets the fish for its abundance of oil. Menhaden are literally vacuumed up at sea, ground up and reduced to fish meal and fish oil, much of which is then used in dietary supplements or as feed in aquaculture, dairy cow, and hog operations.
We’re talking about vast quantities of these small, silvery fish. In 2010, the reduction fishery landed 183,085 [PDF] metric tons of menhaden, followed by the commercial bait fishery, which landed 44,000 metric tons.
The majority of the menhaden harvest is taking place in the state waters off Virginia and a small section of North Carolina—the only Atlantic states that haven’t outright banned menhaden fishing by those looking to produce fish oil. But menhaden are also being harvested in federal waters, three to 200 miles offshore, from New Jersey to North Carolina.
That’s why the upcoming the decision by the ASMFC (and the hearings leading up to it) is so important. It’s possible that board members may consider setting new harvest limits designed to preserve a significantly larger portion of the menhaden spawning stock (i.e. wild fish that are left alone to reproduce).
Read the full article at Grist.
Analysis: The article omits several important facts about the menhaden fishery. Most notably is that, according to the ASMFC, the menhaden fishery is currently not considered to be overfished, and the population is currently meeting its fecundity target.
The article also overstates the importance of menhaden as a source of food for species like bass, and mistakenly implies that menhaden are responsible for cases of mycobacteriosis that have been reported in bass. Bass diets, as well as the diets of the Bay predators, is highly variable and is dependant on several factors independent of the menhaden fishery; menhaden have been found to make up as little as 9.6% of bass diets. A lack of menhaden is also not a likely cause of mycobacteriosis. Rather, it is more likely caused by bass being forced out of the deeper, colder water they normally inhabit by low-oxygen zones, know as hypoxia. These hypoxia zones, caused by run-off in the Bay, force bass to move to warmer waters where that they are ill-suited for, causing them to not feed properly and leading to increased susceptibility to a variety of diseases.
Finally, menhaden's role as a filter feeder, as mentioned in the article, is also in doubt. A recent study found that menhaden's contributions to improving water quality are negligible.