Ken Hinman-1-28-2023 Ken Hinman
Published On July 22, 2019
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The third in a series of blogs, A Question of Science, which looks at changes in the way we assess the health of one of our most important prey species.

In the first two parts of this series I described how the 2010 Atlantic menhaden stock assessment was scrapped after it triggered the first-ever catch restrictions on the menhaden fishery and replaced with one that allowed catches to increase.  Now we begin to look at why.

In a paper presented to the American Fisheries Society at its 2014 Annual Meeting, authors Doug Vaughan and Amy Schueller – past and present chairs, respectively, of the Atlantic States Marine Fisheries Commission’s Menhaden Stock Assessment Subcommittee – provide us with our first clue.

According to The Changing Landscape in Atlantic Menhaden Assessments, prior to 2013 the ASMFC’s “scientists and managers alike were not worried about overfishing or the need for management,” primarily because there had been minimal requirements for management in the past.[i]

Then the ASMFC’s Menhaden Management Board changed its management goals in order to “increase menhaden abundance and availability as a forage species,” raising the threshold for overfishing and prompting regulations to bring the fishery and the menhaden population up to the new standards.[ii]  As a result, the authors point out, the Commission was for the first time relying on its menhaden stock assessment team to determine acceptable catch limits.  But this was a problem, we are told, because “the recent assessment was not deemed useful for management purposes.”  It was “flawed.”

At the time, this sudden resistance to using the assessment came as a big surprise.  The same assessment had passed a peer review by a panel of independent scientists in 2010 and was approved a year later by the Menhaden Management Board (MMB) ”for management use” on the recommendation of the ASMFC’s menhaden technical advisors (Menhaden Technical Committee or TC).

In fact, the ASMFC’s own guidelines stipulate that “if the peer review panel accepts a stock assessment, the results can be used by management to adjust harvest regulations based on the stock status determined by the assessment.”[iii] (my emphasis)

At this point it’s important to understand that changing the management goals may change a stock status determination, as it did in this case, but it does not change the results of the assessment itself.  A stock assessment uses models and other tools to arrive at estimates of population size and fishing mortality to which performance measures or reference points – i.e., targets and limits – are applied.  Changing the reference points does not alter the assessment, only how it relates to these performance measures.

Even after the assessment was updated in 2012 with the latest data from the fishery, and the assessment team first began voicing its concerns about managing with what Vaughan and Schueller characterize as “limited and uncertain data,” the chairman of the TC told the MMB that August:  “The bottom line is that the technical committee feels that even with the uncertainty in the assessment results, we think the stock status determinations are relatively robust,” that is, “overfishing is occurring and the stock is overfished.”

Questions for the Assessment Scientists

So we are left with two questions:

    1. Why did the assessment scientists deem it useful for management purposes in 2011 – when using the old reference points they declared that overfishing was not occurring and no management was needed – but only a year later decided that, with the new reference points, it couldn’t be used to detect overfishing and respond to it?
    2. If managers were asking them to set catch limits based on “a flawed assessment,” why did they, or the independent review panel for that matter, not discover these flaws – which turned out to be so serious as to require fundamental changes to the model, its assumptions and its results – until after the Menhaden Board began using it to regulate the fishery?

We are told that until 2013, they “were not worried about overfishing”.  Perhaps because fishery managers had never needed them to provide information with which to regulate the fishery – despite approving each new assessment for management use and relying on it to determine that management was unnecessary – the assessment scientists were confident the result would be “no overfishing, not overfished,” as always, and everyone would be happy…. until they are not.

Then, and only then, does an assessment they once held up as one of the “most reliable” on the east coast reveal itself as so “flawed” that it is unfit for use.

It is true, as Vaughan and Schueller note, the TC was concerned about being able to project quotas to achieve management goals, since the most recent three years of data, including estimates of fishing mortality, were uncertain.  But the most recent data are always uncertain and making projections is always a concern.  More importantly, it was not this uncertainty that led to completely overhauling the assessment in ways that changed everything.  It was something else.

Complacency among the assessment scientists, who were never worried about overfishing, is certainly plausible, if not excusable. But there is also a more sinister explanation.

In their paper, Vaughan and Schueller correctly advise fishery scientists – that is their audience here – that it is the purview of the managers to make subjective decisions based on the science, weigh the risks, the need for precaution, etc., not the scientists.  “Never allow yourself to place value on one outcome over another.”

But it is no secret that scientists from the menhaden fishing industry had undue influence in the assessment process, or that some members of the assessment team were displeased with the Menhaden Board when it changed the definition of overfishing, to the point of openly questioning the Board’s management goals and the actions they were being asked to provide advice on.

In Part 4 of A Question of Science, we’ll take a look at what went on at two pivotal meetings of menhaden scientists during the 2012 assessment update, events that raised serious concerns about the integrity of the process.

[i] Douglas S. Vaughan and Amy M. Schueller. The Changing Landscape in Atlantic Menhaden Assessments: Best Available Science, Uncertainty, and the Tension between Science and ManagementIn Future of Fisheries:  Perspectives for Emerging Professionals. William W. Taylor, Abigail J. Lynch, and Nancy J. Léonard, editors. American Fisheries Society, July 2014

[ii] An independent review panel, while endorsing the 2010 assessment, advised the managers that the reference points being used to gauge the health of the stock, i.e., fishing mortality limits and abundance thresholds, were set far too low, allowing a menhaden population that was less than 10 percent of its un-fished level to be considered “not overfished”.  See also A Question of Science, Part 2.

[iii] ASMFC Guide to Fisheries Science and Stock Assessments June 2009 Ed. Tina Berger.