WASHINGTON — August 1, 2012 — On July 23, Peter Baker, Director of the Northeast Fisheries Program of the Pew Environment Group, sent an email to supporters urging them to contact the Atlantic States Marine Fisheries Commission and take a number of steps related to the regulation of Atlantic menhaden. Unfortunately, Pew Environment is misleading the public though the selective presentation of facts.
– Pew Environment states for dramatic effect that “overfishing has occurred in 32 of the last 54 years”, but they avoid mentioning that 30 of those 32 instances occurred between 1954-1993. From 1994-2008 (the last 15 years for which there is data) overfishing occurred only twice, most recently in 2008 and only by 0.4%.
– Pew Environment does not mention the work of, among others, Dr. Doug Butterworth of the University of Cape Town, one of the world's leading scientists in the area of mathematical modelling approaches in the assessment of renewable marine resources and Dr. Alexia Morgan, of the University of New England, who is also a consultant with the Ocean Sciences Division at the Pew Charitable Trust, and a contractor with both the New England Aquarium and the Blue Ocean Institute. Drs. Butterworth and Morgan analyzed the results of a menhaden aerial survey conducted by Dr. James Sulikowski of the University of New England, an expert in the area of composition and spatial/temporal distribution of fish communities, and found that the actual menhaden stock size may be more than twice as large as the stock assessment's estimate.
– Pew Environment, while voicing concern about the health of the menhaden population, fails to mention that in the most recent assessment the number of eggs produced was almost double the number below which menhaden would be considered overfished.
– Pew Environment asks its supporters to demand that menhaden management be based on the 2012 menhaden update stock assessment. They fail to mention that because of issues such as a pattern of contradictory historical population estimates, and incorrect assumptions about the age distribution of fish caught by the fishery, the members of the ASMFC Menhaden Technical Committee have deemed that assessment to be severely flawed and not reliable for management purposes.
Analysis in Detail:
In their recent petition, “Protect Atlantic Fish and Fishing – Keep Menhaden Recovery on Track”, the Pew Environment Group misleads the public by selectively quoting the 2010 menhaden stock assessment to give the impression that the status of Atlantic menhaden is significantly more dire than it actually is.
Pew claims, “according to the ASMFC's [Atlantic States Marine Fisheries Commission] peer-reviewed 2010 stock assessment, overfishing has occurred in 32 of the last 54 years and is still occurring.” In reality, most of that overfishing occurred between the 1950s and the 1970s, and incidences of overfishing are much rarer in the recent history of the fishery. In that same 2010 stock assessment, it can be seen that in the last 15 years for which data is 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 threshold determined by the ASMFC. Because menhaden is 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 is much more relevant in determining the health of the species than older, dated statistics.
Pew also fails to make the important distinction that while the 2010 benchmark stock assessment (a peer-reviewed assessment where the assessment methods can be analyzed) determined 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 shows that the species abundance, measured by the number of eggs produced, is at a level that is currently considered healthy, and is nearly twice the level needed in order to be considered overfished.
Contrary to what the petition states, the members of the menhaden fishery do not oppose new menhaden management and are not trying to “derail” the management process. Rather, industry participants have always advocated that any decision be based on the best available science. In the past, members of the fishery have supported efforts by members of Congress to improve the management process and stock assessment model through efforts such as the inclusion of new aerial survey data. The fishery depends on the stability of the stock, and the industry supports any plan to restore the menhaden population that is scientifically justified.
Pew recommends that the 2012 update assessment (an assessment that adds more data to the previous benchmark assessment but does not change the methods) for menhaden, along with the 2010 benchmark assessment, be the sources considered when setting the new annual menhaden quotas. In doing so, Pew goes against the advice of the ASMFC’s Menhaden Technical Committee, which considers the 2012 update assessment to be severely flawed and not a suitable reference for future management decisions. Many of the flaws present in the 2012 update assessment were first noticed in the 2010 benchmark assessment.
At the last Menhaden Technical Committee meeting, the committee noted that the updated assessment revealed a retrospective pattern in the model, meaning that the estimates in previous population assessments contradicted the population estimates in the most recent assessment, and needed to be revised in order to fit the more current data. With the addition of the 2012 update assessment results, it was found that, from 2006 to 2010, the menhaden assessment model showed a pattern of underestimating the population size and overestimating the fishing mortality rate. This indicates that the model being used for menhaden assessments may be too pessimistic, implying that more fish are dying than actually are. The appearance of retrospective patterns in stock assessments is an indication that a particular assessment model may not be working and that the data being produced is not reliable.
A widely acknowledged flaw in the current menhaden assessment process is that very little data from the northern range of the menhaden population, an area that extends from New Jersey to Maine, is included in the assessment. To address this lack of data, Dr. James Sulikowski, of the University of New England, conducted an aerial study in 2011 of the area and determined that significant amounts of menhaden are located there. In reviewing this study, Dr. Doug Butterworth and Dr. Alexia Morgan determined that over two times as many fish may exist than are accounted for in the assessment. Because the assessment draws much of the data used to calculate population estimates from fishery data, these fish are not included. This is reflected in the assessment’s selectivity pattern, the graphical reflection of what kinds of fish are available to be caught by the fishery.
The menhaden assessment model has a “flat-topped” selectivity, which assumes that for the commercial fishery, all adult fish age three and older are equally likely to be caught by the fishery. When this assumption is graphed, the vulnerability to fishing increases until the age of three, at which point the fish are assumed to be caught by the fishery. Here, the selectivity curve pattern plateaus at maximum selectivity, creating a flat top.
In the 2010 peer review of the assessment, the reviewers suggested that, instead of the flat-top selectivity, a different selectivity might better reflect the fishery’s catch. Menhaden become increasingly vulnerable to being caught as they grow to three years old, and then become increasingly less susceptible to harvest. So, the true selectivity curve for the fishery would take a different shape. Because the fishery only catches a high proportion of the middle age group of one to three year old fish, the likelihood that the fishery will catch these groups is much higher than other age groups. The increasing availability of menhaden up to the age of three, and the decreasing availability beyond that age creates a curve that is bell-shaped. This is known as a “dome-shaped” selectivity curve.
The 2010 peer review recommended that the “dome-shaped” selectivity be used to represent the commercial fishery in southern waters, because they could not access the older, larger fish that were found by the Sulikowski aerial survey to inhabit the northern waters during the fishing season.
These issues have led the Menhaden Technical Committee and Stock Assessment Subcommittee to consider recommending that the ASMFC Menhaden Management Board conduct a new benchmark assessment as soon as possible, rather than using the critically flawed 2012 update for future management purposes.
Because the most recent data available is from 2008, the current health of the menhaden population is unknown. The next full benchmark assessment will not be available until 2015 at the earliest. Assessments are conducted in a three-year cycle , with each three year period ending in either an update assessment or a peer-reviewed benchmark assessment. 2011 was the end of a cycle resulting in an update assessment, which was released this year. Pew is suggesting that the ASMFC make severe cuts in the beginning of a new cycle when only a flawed update assessment is available.
Enacting regulations based solely on data that is either out of date or scientifically questionable does not serve the goal of good, science-based management, especially when the result will cause definitive economic harm to Virginia’s Northern Neck, home of the Atlantic menhaden reduction industry. A recent economic impact study conducted by the Virginia Institute of Marine Science highlighted the importance of the industry to this rural area of Virginia: the reduction fishery employs almost 300 people directly, and many more indirectly, and contributes more than $80 million in economic output to the Northern Neck. Without the reduction fishery, employment in the region would decrease by 8 percent and economic output by 14 percent. Enacting a new quota now could lead to a bad economic situation, and could be considered bad management with no science-based rationale for setting quotas and no recent, reliable stock assessment as a reference.
Citations:
Atlantic States Marine Fisheries Commission, “Stock Assessment Report No. 10-02 of the Atlantic States Marine Fisheries Commission Atlantic Menhaden Stock Assessment and Review Panel Reports ,” 2010
Atlantic States Marine Fisheries Commission, “Stock Assessment Report No. 10-02 of the Atlantic States Marine Fisheries Commission Atlantic Menhaden Stock Assessment and Review Panel Reports – Figure 8.4 Annual Fishing Mortality ,” 2010
Saving Seafood, Areas of Concern in ASMFC’s Atlantic Menhaden Assessment Update , 2012
Atlantic States Marine Fisheries Commission, “Menhaden SAS/TC Conference Call 5/29/12 ,” 2012
Kirkley, James E. “An Assessment of the Social and Economic Importance of Menhaden (Brevoortia tyrannus)(Latrobe, 1802) In Chesapeake Bay Region ,” 2011
Atlantic States Marine Fisheries Commission Menhaden Management Board, “Draft Proceedings of the Atlantic States Marine Fisheries Commission Menhaden Management Board ,” May 2, 2012
Sulikowski, James; Morgan, Alexia; Carlson, Amy; Butterworth, Doug, “Inferences from aerial surveys on the abundance of Atlantic menhaden from outside the normal fishery range : Implications for improved management of the resource ,” 2012,
NOAA FishWatch, “Overfishing vs. Overfished: The Same Thing? ” 2012
Thorson, James; Prager, Michael, “Better Catch Curves: Incorporating Age-Specific Natural Mortality and Logistic Selectivity ,” Transactions of the American Fisheries Society, 2011
Atlantic States Marine Fisheries Commission, “Atlantic Menhaden Stock Assessment Subcommittee Conference Call Summary ,” June 15, 2012
Wittman, Robert; Michaud, Michael, et. al., Letter to John V. O’Shea and Sam Rauch , April 9, 2012
NOAA Chesapeake Bay Office, “Menhaden Fact Page ”
Atlantic States Marine Fisheries Commission, “Addendum to Amendment I to the Interstate Fishery Management Plan for Atlantic Menhaden ,” August 2004