HOW TO SHOOT YOURSELF IN THE FOOT AT THE MID-ATLANTIC FISHERY MANAGEMENT COUNCIL

Let’s start with the basics.  Fisheries management is a science, that takes years of sweat and study to learn.

To do it well requires multiple sources of accurate data, which are then incorporated into complex computer models, which models are, in turn, subject to review by a panel of independent experts, who determine whether both the models and the data are suitable for management purposes.

It also requires that fishery managers recognize that their data, and their findings, are not perfect, but instead always incorporate a greater or lesser amount of uncertainty.  Identifying sources of uncertainty is important, and can allow managers to account for at least some of the unknowns when estimating the health of a stock or recommending future harvest levels.

Thus, at last week’s meeting of the Mid-Atlantic Fishery Management Council, attendees were advised that major sources of uncertainty in the bluefish operational stock assessment included the revised Marine Recreational Information Program (MRIP) estimates of anglers’ catch and effort, the increased importance of dead discards in the assessment, uncertainty as to whether the full allowable biological catch will actually be caught, the relatively scarce data regarding the 60% of the biomass that is six years old or older, uncertainty about how the MRIP index and MRIP estimates interact in the stock assessment, and whether commercial discards are larger than currently believed.

Because of those and other sources of uncertainty, managers are unable to provide a perfectly precise estimate of any species’ spawning stock biomass, or of any other value used to assess and/or manage the stock.  So, in the case of the bluefish operational stock assessment, instead of only providing a single point estimate for the size of the spawning stock biomass, the assessment said

“Spawning stock biomass (SSB) was estimated to be 91,041 (metric tons) in 2018, about 46% of the updated target biomass reference point SSB_MSY proxy=SSB_35%=198,717 (metric tons), and 92% of the SSB_threshold=99,359 (metric tons).  There is a 90% chance that SSB in 2018 was between 66,840 and 99,299 metric tons.  [emphasis added, internal references deleted]”

That last sentence, which I emphasized in the quote above, tells us a lot. 

First, it tells us that after incorporating all of the uncertainty that the assessment team was aware of, the best they can tell us, employing what is referred to as a “90% confidence interval,” is that 2018 spawning stock was somewhere between 66,840 and 99,299 metric tons; the 91,041 metric ton point estimate was effectively the peak of the probability bell curve that then fell away to—and past—those values.

It also tells us that there is very little doubt that the bluefish stock is overfished, and in need of rebuilding, for even the high figure in the range provided, 99,299 metric tons, would fall very slightly below the spawning stock biomass threshold that defines an overfished stock.  However, it does not tell us that the stock is overfished with absolute certainty.  Because a 90% confidence interval was used, there remains a 10% chance that the spawning stock could be either smaller than 66,840 or larger than 99,299 metric tons—although given the shape of the curve, the likelihood is that if the stock fell outside of the 90% confidence interval, it would do so on the low side.

Apologies for getting so deep into the statistical side of things, but I still have to dive just a bit deeper before I get to the “shoot yourself in the foot” part of this essay. 

That’s because uncertainty doesn’t only impact potential size of the confidence interval surrounding each important point estimate; it’s because higher uncertainty also raises the risk that management decisions will go wrong, and won’t adequately protect fish stocks.

So the Mid-Atlantic Council’s Scientific and Statistical Committee is governed by a policy which sets one of three “coefficients of variation” (CV) that are used to create buffers that account for uncertainty and its potential for increased risk.  

A CV of 60 is used when uncertainty is relatively low, while a CV of 100 is employed for more typical levels of uncertainty, and a CV of 150 used when uncertainty is particularly high.  The buffer between the overfishing limit and the allowable biological catch—which is often equivalent to the annual catch limit—established to account for scientific uncertainty, typically increases when higher CVs are set.

In the 2015 benchmark bluefish stock assessment, the level of uncertainty was deemed low enough to justify a CV of 60, but due to the uncertainty inherent in the bluefish operational assessment, that CV was increased to 100.  At the October 8 Mid-Atlantic Council meeting, when explaining why a CV of 100 was chosen, the Chair of the Council’s Scientific and Statistical Committee advised that

“The chief uncertainty with Bluefish relates to patterns in the revised MRIP estimates.”

And that makes sense.  The revised MRIP methodology is new, and even though it has undergone rigorous testing and review, it is only prudent to make sure that it is producing more accurate estimates before placing unquestioned reliance on its results.

Thus, in fisheries such as bluefish and black sea bass, where recreational catch plays a large role in the health of the stock and the MRIP estimates have a big impact on the assessments and on future projections of catch and stock health, managers are adopting larger CVs, and so reducing the recreational harvest limit, in order to account for the increased uncertainty.

But here’s where the whole “shoot yourself in the foot” thing comes in.

While scientists are exhibiting due caution with respect to the new MRIP estimates, some members of the recreational community, including those who sit on recreational advisory panels, have gone beyond caution, and have aggressively rejected the new MRIP approach.  For example, the report of the Summer Flounder, Scup and Black Sea Bass Advisory Panels’ meeting reported that in the recreational scup fishery,

“Multiple advisors said that they had no faith in the data from the Marine Recreational Information Program (MRIP), which they see as inaccurate and fundamentally flawed.”

The report of a September 24 Advisory Penal webinar states that, with respect to black sea bass,

“Many advisors said they have no trust in the Marine Recreational Information Program (MRIP) data.  One advisor said it’s not true that we now know that recreational catch is higher than we previously thought because we don’t know that the revised numbers are accurate.”              

At the October 9 meeting, Council staff quoted advisors who called some MRIP data “unbelievable.”

Often, many of the advisors, and many fishermen, don’t think that anyone is listening to their complaints, but comments at the October 9 meeting demonstrated that just isn’t true.

One of the topics that the Council and ASMFC's Summer Flounder, Scup and Black Sea Bass Management Board discussed that day was possible changes to the commercial/recreational allocation.  

The Council and Management Board ultimately decided to begin work on an amendment that might do just that.  One of the justifications for revisiting allocation was that the new MRIP numbers indicated that recreational harvest was, and had always been, higher than previously believed, even during the base years that determined how the commercial/recreational allocations would be set.

Naturally, some of the commercial fishermen present, and even a few who supposedly represent the angling sector, expressed doubt about the accuracy of the MRIP estimates, and questioned whether the Council could justify reallocating fish based on MRIP estimates that, as evidenced by the higher CVs, even the Scientific and Statistical Committee seemed to doubt.

And that’s when the most interesting comment was made by the SSC’s Chairman.  

It seems that the Scientific and Statistical Committee’s cautious approach to MRIP wasn’t merely due to the newness of the revised estimates, and the need to be careful until there are a few more years of data to confirm the estimates’ validity. 

It seems that the SSC has been listening very carefully to the advisors’ criticisms of MRIP, and that those criticisms have led the SSC to consider why the MRIP estimates seem to diverge so much from the advisors’ views of the fishery.  Thus, those criticisms, and the questions that they raised, were one of the factors that caused the SSC to increase the CVs in a couple of fisheries, and so lower the recreational harvest limits for 2020 and 2021.

Thus, by their relentless criticism of MRIP, some of those advisors, who typically argue for higher recreational harvest limits, helped to convince the SSC to increase the CVs, and so lower the harvest limits in upcoming years.

Which is why it’s probably a good idea to thoroughly understand the management process, and how each factor plays into management decisions, before shooting off your mouth.

Because you might end up shooting off your own foot as well.