February 26, 2013 — The following is an excerpt from the Chesapeake Bay Foundation's Winter 2013 "Bay Bound" newsletter.
They've been called "the most important fish in the sea." Small, silvery, and packed with nutritional value, menhaden are filter feeders that consume plankton and in turn are food for striped bass and other important fish, as well as marine mammals and sea birds. They are in effect a critical link in the marine food web. But in 32 of the past 54 years (through 2008), menhaden were overfished, and they are now at their lowest level on record.T
Many people have never even heard of this boney, oily, unappetizing fish (also known as bunker or pogy). But without this little unsung hero the Bay's ecosystem would likely collapse. The Bay's other valuable fish like striped bass (rockfish), bluefish, and summer flounder rely heavily on menhaden for nutrition as do sea turtles, osprey, and other fish-eating marine mammals and seabirds.
Further, the Chesapeake Bay is the most important nursery area for Atlantic menhaden. From spring through fall, juveniles as well as adults would be found throughout the entire Bay when the population was healthy.
Read the full story from the Chesapeake Bay Foundation
Analysis: The Chesapeake Bay Foundation (CBF) story, "The Chesapeake's Unsung Hero," misconstrues data on Atlantic menhaden stock assessments along with the causes for the species' declining numbers.
How Overfishing Becomes Overstated
The article states, "in 32 of the last 54 years (through 2008), menhaden were overfished, and they are now at their lowest level on record." This claim is often echoed in publications without appropriate context. Nearly all overfishing occurred between the 1950s and the 1970s. In the last 15 years for which data are available, from 1993 to 2008, overfishing occurred only twice. The last recorded instance of overfishing was in 2008, when the fishery was just 0.4 percent over the overfishing limit determined by the Atlantic States Marine Fisheries Commission (ASMFC) at that time.
Incidences of overfishing are much rarer in recent history. Because menhaden are a comparatively short-lived species (living from 10-12 years), and the average menhaden produces a high number of eggs during its lifetime, the most recent data are much more relevant in determining the health of the species than older, dated statistics.
CBF’s article also fails to make the important distinction that while the 2010 benchmark stock assessment determined that menhaden were experiencing slight overfishing (meaning that the number of fish caught exceeded the mortality level set by the ASMFC), it concluded that the stock was not overfished (meaning that the population is still producing enough eggs to sustain itself). In fact, the assessment showed that the species abundance, measured by the number of eggs produced, was at a level considered healthy, and was nearly twice the level needed in order to be considered overfished.
The current status of menhaden is unknown. In a January 2013 meeting, the AMSFC concluded that there is not enough evidence to determine the status of the stock.
Is the Fishing Industry to Blame?
Though menhaden numbers have declined, the Foundation blames the fishing industry rather than accounting for the many natural factors currently affecting menhaden reproduction, stating: “Taking too many young fish both greatly diminishes the spawning potential of the population and reduces their availability to predators.” Federal scientists, through a number of studies, have repeatedly concluded that environmental factors, and not fishing, are affecting menhaden numbers.
On their website, the National Oceanic and Atmospheric Administration’s (NOAA) Chesapeake Bay Office explains, “menhaden recruitment appears to be independent of fishing mortality and spawning stock biomass, indicating environmental factors may be the defining factor in the production of good year classes.”
Federal scientists take issue with this assumed link between the menhaden fishing industry and the success of the stock, and agree that we should focus on environmental conditions.
A 1991 study on menhaden management in Marine Fisheries Review by D.S. Vaughan and J.V. Merriner, of NOAA Fisheries, concluded, “it appears that managing the fishery to maintain large numbers of spawners may prove fruitless since environmental conditions appear to outweigh the availability of spawners (as numbers or eggs) in controlling subsequent recruitment.”
Similar studies from the ASMFC and NOAA have shown a poor correlation between the number of adult menhaden available to reproduce and the number of viable offspring that survive to join the population, indicating that factors other than fishing mortality affect recruitment.
Fluctuating Stocks
Claims that menhaden "are now at their lowest level on record” fail to provide adequate context. The chart included in the Foundation’s article illustrates that current declines in the menhaden stock began in 1983. However, the chart also shows that these levels are not new for the population. As it illustrates, fluctuations in menhaden biomass have occurred over the 50-plus years for which data are available.
The Providence Journal, in an analysis that found the claim of a 90 percent drop in menhaden abundance by the Pew Environment Group to be “mostly false,” presented an in-depth discussion on the fluctuations over the past half-century.
These fluctuations are based on the strength of menhaden recruitment (the number of menhaden born within a respective year that enter the spawning stock) with current biomass levels similar to those seen in the late 1960s, when biomass was lower. The late 1970s and early 1980s saw several years of especially strong recruitment, followed by years of high biomass.
Sticking to the Science
The article also includes a designation of menhaden as “the most important fish in the sea,” without an explanation of the phrase’s origin. Although menhaden are economically and biologically important, this phrase is entirely qualitative. It stems from the title and premise of the book, The Most Important Fish in the Sea: Menhaden and America, by Rutgers University English Professor, Dr. H. Bruce Franklin. This hyperbolic statement is based on judgments made by the author, rather than scientific evidence. Promulgating this idea represents only the authors’ opinion, rather than any scientific consensus.