The following is an excerpt from the Washington Monthly story by Alison Fairbrother:
May 10, 2012 – Harvested by the billions and then processed into various industrial products, menhaden are extruded into feed pellets that make up the staple food product for a booming global aquaculture market, diluted into oil for omega-3 health supplements, and sold in various meals and liquids to companies that make pet food, livestock feed, fertilizer, and cosmetics. We have all consumed menhaden one way or another. Pound for pound, more menhaden are pulled from the sea than any other fish species in the continental United States, and 80 percent of the menhaden netted from the Atlantic are the property of a single company.
To determine whether or not Omega Protein is overfishing menhaden, the government relies on a set of methods and calculations that are mystifying in their complexity. Every time Omega’s captains return to the Reedville port, they report their daily “unload”—how many tons of fish they have removed from the water. Onshore, a government agent periodically examines a handful of fish scooped from the ship’s hold and uses them to estimate the size and age composition of the day’s catch. Information from these samples, collected over the course of the fishing season, are collated with the captain’s logs, and the data goes to a single scientist for processing at the National Oceanic and Atmospheric Administration’s (NOAA) fishery lab in Beaufort, North Carolina. There it is gathered together with harvest information from the handful of smaller companies that fish for menhaden along the coast to sell as bait, as well as trend data from a few independent scientific surveys. This stew of data is fed into a mathematical fishery assessment model that takes many scientists and several months to run. The process generates an estimate of how many eggs the current menhaden population is producing, compared to how many eggs there would be in an unfished, pristine environment. This information is handed over to a sleepy, part-time board of regulators called the Atlantic States Marine Fisheries Commission (ASMFC), who decide whether fish stocks are at a safe level or if there should be concerns about overfishing.
Read the full story at Washington Monthly.
Analysis: Alison Fairbrother’s, "A Fish Story: How an Angler and Two Government Bureaucrats May Have Saved the Atlantic Ocean," published on May 10 in Washington Monthly, makes several key omissions about the current state of scientific thought on the menhaden fishery. These omissions call into question the article’s portrayal of the fishery as being near-collapse due to a lax regulatory environment, and reveal a more complex picture of the fishery than the article’s reporting displays.
The central question of both the article and the current public debate concerning menhaden management is what the best available science says, and does not say, about menhaden. This is especially true when the article attempts to explain the scientific calculations that are used when setting fishing limits and determining when overfishing has occurred. The article misrepresents the calculation of the reference point – a value that, if exceeded, indicates that overfishing has occurred in a population.
In discussion of this reference point, the article states that it is based on the Maximum Spawning Potential (MSP), an estimate of the reproductive capability of a theoretically unfished population. It claims:
"This estimate then goes before the ASMFC Menhaden Technical Committee, which is made up of NOAA scientists and biologists from state fisheries agencies. Their job is to weigh the menhaden’s current spawning potential against an estimate of how many eggs menhaden would produce in an imaginary world with no fishermen. The ratio of these two figures is called “maximum spawning potential.”
It is from these estimates that the committee derives the real magic number: the threshold below which the menhaden population would be unable to replenish or sustain itself. This threshold, which is debated and then voted on by the full commission, is called a “reference point.” The reference point currently in use for menhaden is 8 percent of maximum spawning potential. That is to say: according to the ASMFC, the Atlantic menhaden population can safely be fished down to 8 percent of the spawning potential that it would possess in a natural state."
The article inaccurately describes how the reference points were determined. While the reference point is expressed as a percentage of MSP, the reference points used in the 2010 benchmark assessment were not MSP-based. The reference points were, instead, based on measures of fishing mortality and fecundity. For a detailed explanation of how the reference points were calculated, see the “Biological Reference Points” section in “Addendum 1 to Amendment 1 to the Interstate Fishery Management Plan for Atlantic Menhaden,” beginning on page 4.
The article also states that the reference point for menhaden is much lower than the reference point for striped bass. While the level of MSP in that assessment was 8%, that value was not used as one of the reference points. An updated assessment is currently being conducted. More importantly, comparing the menhaden reference point to the striped bass reference point ignores an important reality: that the average menhaden lays many more eggs than a predator species like striped bass, and thus are able to increase population size from a smaller starting stock biomass.
The article also fails to note that, historically, MSP levels appear to be poorly correlated with menhaden recruitment (the number of menhaden that survive to join the migratory population). It criticizes the current reference point of 8 percent as too low. But this is actually higher than historic averages. Since the 1950s, the reference point has averaged approximately 6 percent MSP. In the same period, menhaden recruitment fluctuated dramatically, rising to a high in the late 1970s when the reference point equaled only 2 percent MSP. Although reference points this low are not considered optimal for management today, it is important to be aware of the historic performance of the population to fully understand the current stock and the parameters used to analyze its health.
These scientific arguments are quickly dismissed by the article, which states:
"At every moment in this long history, the reduction industry has denied, counterintuitively, that fishing has any impact on the number of menhaden in the Atlantic. A publication of the United States Oil and Guano Association from 1884 asserted, ‘The plentitude or scarcity of sea fish is wholly independent of the operations of man, but is determined by the forces of nature.’ To this day, Omega Protein maintains that menhaden have been subject to a historical pattern of ebbs and flows, driven by external factors like pollution and poor recruitment."
But Omega Protein is not alone in its assertion. Both the commission responsible for regulating menhaden, the Atlantic States Marine Fisheries Commission (ASMFC), and the agency responsible for US fisheries science, the National Oceanic and Atmospheric Administration (NOAA), agree that environmental conditions, rather than commercial fishing efforts, are the greatest influences on the menhaden population. For example, in its 2010 stock assessment, the ASMFC writes, “past performance of Atlantic menhaden suggests it has gone from periods of low recruitment and fecundity to periods with high recruitment and fecundity, while sustaining moderate to high landings.” They conclude, “[menhaden] population fluctuations are almost entirely driven by non-fishery sources.” Similarly, NOAA’s Chesapeake Bay Office concludes, “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.”
The article also alleges that the current rate of menhaden fishing is having a negative impact on predator fish species, such as striped bass, even though the science behind some of these claims is inconclusive at best. For example, the article claims that a lack of menhaden caused the spread of mycobacteriosis, a bacterial infection that is currently present in around 76 percent of the Chesapeake Bay striped bass population, according to the Virginia Institute of Marine Science. The article goes on to state that striped bass, “were quite literally starving,” which lead them to contract mycobacteriosis, “a serious infection related to malnutrition.”
A 2009 study by Dr. David T. Gauthier in The Veterinary Journal reviewing the available scientific literature concluded that there is currently no consensus about the primary cause of mycobacteriosis, and it is not known which of several potential factors has the greatest influence. However, like much of the Bay’s current ecological problems, environmental degradation from nutrient runoff is likely to play a key role. Excess nitrogen and other nutrients that enter the Bay, from sources such as agriculture and urban development, lead to algal blooms, the excessive growth of phytoplankton and algae. When these blooms die off, the process of decay consumes the oxygen in the surrounding water, creating hypoxic (low oxygen) areas. These hypoxic areas are usually in deeper, cooler waters, which bass inhabit during the summer. But because the hypoxic conditions make them uninhabitable, the bass are forced into shallower, warmer waters for which they are not ideally suited. The sub-optimal temperature makes them unable to feed properly, and makes them more susceptible to disease. This phenomenon, known as the thermal niche/oxygen squeeze, was documented in striped bass in reservoirs by Charles Coutant, a scientist now retired from the U.S. Fish and Wildlife Service. Coutant published three scientific journal articles (one in 1988 and two in 1990) describing the same phenomenon for striped bass in the Chesapeake Bay.
It is possible that a relative increase in the striped bass population, which has coincided with a relative decline in the menhaden population, may be a contributing factor to the spread of the disease. But striped bass, despite what the article indicates, are not exclusively reliant upon menhaden for their diet. Striped bass are opportunistic predators, and consume 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. Therefore, Chesapeake Bay striped bass population stability is not dependant on menhaden population fluctuations.
Though the article asserts that ASMFC science, “has now become a huge liability,” for Omega Protein, the science is not as clear-cut as it indicates. As the article indicates, the ASMFC recently revised its stock assessment model. When this new model was applied to previous years, it was retroactively determined that overfishing had occurred in 32 of the last 50 years. This reflects the fact that Omega Protein and other fishing companies fished according to the regulations present at the time, which were only subsequently found to have lead to overfishing. More relevant to the current state of the fishery is that overfishing has only occurred once in the last decade, and then only .4% over the reference point.
And while the assessment judged that overfishing is occurring, meaning that the number of fish caught exceeds the mortality limit imposed by the ASMFC, the stock is not currently overfished, meaning that it is currently producing enough eggs to rebuild itself. Because the ASMFC has determined that there already are enough eggs being produced by the menhaden stock, it is most likely that a factor other than fishing mortality has led to low spawning. Equally important, this makes it unclear whether the decreased catch limits environmental advocates prefer would effectively solve the problem.