November 8, 2012 — The following is an excerpt from a story published by the Chesapeake Bay Journal.
In the 1940s, a company in Reedville, VA, that fished Atlantic menhaden for "reduction" (industrial processing) described the little silvery fish as "made for Man to harvest." To them, the supply was inexhaustible, with no other value except crab pot bait.
Today, that viewpoint seems outrageous, but it dies hard. It has caused big problems for the menhaden, aka bunker, pogy, or alewife. These herring relatives have ranged along the coast in astronomical numbers for thousands of years. Most of the fish winter and spawn off the Carolina coast.
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Why such vast numbers? Simple: Menhaden eat low on the food web. They are omnivorous filter feeders, straining whatever water they swim through. Depending on a fish's age, it might catch phytoplankton (tiny algae cells), zooplankton (tiny invertebrate animals), or — especially in estuaries — detritus (semi-decayed plant material).
The success of this ecological niche lies in tapping these vast food sources and converting them to oily, protein-filled flesh for the next level of the coastal food web. Menhaden feed predators like rockfish, bluefish and sea trout, plus ospreys, loons, gannets and marine mammals. Their value to these fish and birds is immense.
We humans make scant use of menhaden as food. They are mostly valued as bait for finfish and shellfish, or for their oil. The oil goes into industrial products, including paints, cosmetics and Omega-3 diet supplements. The leftover high-protein meal becomes livestock feed.
The reduction industry came to the Chesapeake in the 1870s. Today, small airplanes help find menhaden schools, then skillful captains and crews use purse seines to surround them. The harvest is highly automated, using twin 32-foot "purse boats" and 175-foot-long "steamers" (mother ships). Reedville is the fishery's hub. The industry supports 250 good-paying jobs. (To learn more, visit the Reedville Fishermen's Museum at www.rfmuseum.org.)
As bait, the menhaden's oily flesh exudes a trail to lure crabs and lobsters, as well as rockfish and bluefish. It has been particularly valuable in the Chesapeake since the invention of the crab pot in 1928.
The bait fishery is concentrated between Virginia and Massachusetts. Every watermen's village from Hampton Roads to Rock Hall is dependent on bait as well as coastal North Carolina, Delaware Bay, New Jersey and Long Island. With the recent closure of most river herring fisheries because of depleted stocks, menhaden are now critical for New England's lobster fishery. Though more spread out than the reduction fishery, the bait fishery supports more jobs.
How many menhaden do these human fisheries need? Several-hundred-thousand metric tons per year. According to peer-reviewed fishery science, though, the current stock stands at only 8 percent of an unfished population, the lowest point on record. Are we wise enough to back off before we crash it?
Consider these alarming statistics: Historically, they provided 70 percent of an adult rockfish's diet, but that number has fallen to 8 percent. The percentage for Chesapeake ospreys has fallen from 70 percent to 28 percent, causing serious chick mortality.
Read the full story at the Chesapeake Bay Journal
Analysis: While the Chesapeake Bay Journal correctly details the many ways in which menhaden are economically and ecologically significant, several of the statistics cited overstate the problems currently facing the stock, specifically in reference to the size of the current menhaden population and their role in the Chesapeake food chain.
The author writes, “the current stock stands at only 8 percent of an unfished population, the lowest point on record.” This refers to Maximum Spawning Potential (MSP), which is an estimate of a theoretically unfished population, rather than an historical figure. While menhaden are currently at an MSP of around 8 percent, this does not by itself mean that the population is overexploited or that there are too few menhaden. Historically, in the 50-plus years of data available for the fishery, MSP has averaged less than 10 percent — sometimes dipping even lower than the current 8 percent rate. At that level, the fishery has traditionally been able to rebuild itself, given the large number of eggs that an individual menhaden can produce. According to recent assessments, the stock is currently producing enough eggs to sustain itself, meaning that it is not overfished.
The article also makes the claim that menhaden’s current population level is having a negative impact on striped bass, stating, “historically, [menhaden] provided 70 percent of an adult rockfish’s diet, but that number has fallen to 8 percent,” and that, “at 8 percent, there aren’t enough to go around.” However, this is not clearly the case given the available data on striped bass diet. Striped bass are opportunistic predators, consuming a variety of prey species depending on their availability and location. The 2010 annual report of the Chesapeake Bay Multispecies Monitoring and Assessment Program noted that bay anchovies, small crustaceans, and worms are all significant parts of the striped bass diet, in addition to menhaden. Given the variety and variable nature of striped bass diets, it is not likely that they are dependent on any one single food source for survival.