SUMMER FLOUNDER: A FISHERY IN TRANSITION

 

On the morning of August 8, the Mid-Atlantic Fishery Management Council held a joint meeting with the Atlantic States Marine Fisheries Commission’s Summer Flounder, Scup, and Black Sea Bass Management Board, to consider specifications for the 2024 and 2025 fisheries.

The meeting didn’t run very long, and was remarkably free from controversy.  However, it did reveal that the summer flounder fishery might be undergoing real, and perhaps long-lasting, changes, that will cause landings over the next two years to be substantially reduced.

The problem seems to be focused around an extended period of below-average recruitment of new fish into the population.  The average annual recruitment of Age 0 summer flounder for the period 1982-2022 is 51 million fish.  But for the period 2011-2022, recruitment fell to an average of just 36 million fish per year, with annual production ranging between 27 and 43 million annually. 

Initially, it appeared that a strong year class of about 61 million fish was produced in 2018, and that such year class might help boost summer flounder abundance.  Unfortunately, data compiled since then indicates that the size of the 2018 year class was initially overestimated, and that its true size was around 43 million Year 0 summer flounder, placing it well below the long-term average.

While the 15 million recruit difference between the long-term average and the average over the past 12 years is stark enough on its face, it nonetheless fails to convey the full magnitude of the recent decline in recruitment, since the years 2011-2022 comprise over one-quarter of the long-term recruitment time series, and the low recruitment during those 12 years drags down the long-term average.  If average recruitment for the period 1982-2010 was compared to the average for the past 12 years, the difference would be even more marked.

The stock’s persistent failure to produce even a single average year class is now causing fishery managers to ask whether they might be seeing a fundamental, long-term alteration—what one Mid-Atlantic Council staff member referred to, during the meeting, as possible “regime change”—in summer flounder productivity, although they have not determined why such reduced productivity is occurring. 

Lower recruitment isn’t the only change that scientists are seeing.  It was noted at the meeting that summer flounder seem to be smaller, at any given age, than they had been in the past, and that the proportion of males in the population is increasing.  At the same time, it seems that current regulations are allowing some summer flounder to live to older ages.  In 2018, NMFS’ sampling of commercially caught fish turned up a 22-inch male summer flounder believed to be 20 years old; it is the oldest summer flounder ever collected.  Two other fish sampled in the same year, one a male and one a female, were believed to be 17 years old.  The presence of such large fish led Council staff to note that

“These samples indicate that increased survival of summer flounder over the last two decades has allowed fish of both sexes to grow to the oldest ages estimated to date.”

Still, the changes affecting the stock present the summer flounder with an uncertain future.  A management track stock assessment released in June 2023 commented that

“Declining trends in growth rates and changes in the sex ratio at age may change the productivity of the stock and in turn affect estimates of the biological reference points.  Changes in growth, maturity, and recruitment may be environmentally mediated but mechanisms are unknown.”

Overestimating the size of the 2018 year class also had more immediate impacts.  The 2023 management track assessment found that the summer flounder stock experienced overfishing in 2022, something that caught a lot of people by surprise, because the overfishing limit, which had been set earlier, was never exceeded.  Kiley Dancy, a biologist employed by the Council, explained what happened in a July 13 memo to Dr. Christopher Moore, the Council’s executive director.

“Despite the previously specified [Overfishing Limits] not being exceeded…the new 2023 [management track assessment] now estimates that overfishing was occurring for summer flounder in 2022.  This is primarily driven by the latest model run adding three years (2020-2022) of fishery catch, survey catch, and biological data (including continued decreases in mean weights and maturities at age).  While the average retrospective errors for [spawning stock biomass] and [the fishing mortality rate] are small, adding multiple years of data contributed in this case to overestimating stock size and underestimating [the fishing mortality rate].  The previous [Overfishing Limits] were set using an assessment with terminal year 2019 and creating biomass projections for 2020-2023, which now appear to have been overoptimistic.”

In other words, we all thought that the summer flounder biomass was bigger than it actually was, so fishermen were allowed to take more fish than they would have, had the actual size of the stock been known.  As a result, the 2022 fishing mortality rate was 103% of the fishing mortality threshold, and overfishing occurred.

On August 8, the Council and Management Board set about fixing the problem.

The first step was to set an Overfishing Limit that was in accord with both the actual size of the stock and with the current level of scientific uncertainty.  That job fell to the Council’s Scientific and Statistical Committee, which reduced the OFL from 34.98 million pounds in 2023 to 22.98 million pounds in 2024 and 2025 (the SSC also gave the Council the option of setting varying OFLs of 22.98 million pounds in 2024 and 25.39 million pounds in 2025, but the Council preferred not to do so).  Such change would lower the Acceptable Biological Catch from 33.12 million pounds in 2023 to 19.32 million pounds in 2024 and 2025 (again, the Council also decided against setting a varying ABC of 17.88 million pounds in 2024 and 20.75 million pounds in 2025).

Such reductions will naturally lead to substantial reductions in both the commercial quota and the recreational harvest limit over the next two years.  For both sectors, reductions are expected to be in the 40 percent range.

The Council settled on a commercial quota of 8.79 million pounds, which is a 42 percent reduction from the 2023 quota, but only about a 30 percent reduction from actual 2022 landings. 

The Council also set a recreational harvest limit of 6.35 million pounds, which represents a 40 percent reduction from the 2023 RHL, but just a 28 percent reduction from estimated 2022 landings.

We don’t yet know how the reduction in the recreational harvest limit might affect 2024 regulations.  That decision will wait until the December joint meeting of the Council and Management Board, when managers will have a better estimate of what anglers landed during the 2023 season.  

Of course, given the recent discovery that the Marine Recreational Information Program may be overestimating recreational fishing effort, and so recreational catch and landings, by somewhere between 30 and 40 percent, there is going to be significant uncertainty as to what recreational landings really were this year.  Depending on whether, and how, that uncertainty is addressed when calculating the confidence interval surrounding the estimate of recreational landings, the lower recreational harvest limit might or might not have a big impact on the regulations governing the recreational summer flounder fishery next year.

That’s because recreational management measures are now governed by the so-called “Percent Change Approach” of the Harvest Control Rule adopted last year.

Summer flounder biomass is estimated to be 83 percent of the target level, which is deemed “low” abundance pursuant to that approach.  If the new recreational harvest limit falls within the confidence interval bounding the estimate of recreational summer flounder harvest (more precisely, what such harvest would be if current rules remained unchanged),  the Control Rule would require that new management measures reduce landings by the difference between the harvest estimate and the recreational harvest limit, provided that such reduction not exceed 20 percent.

However, if the new recreational harvest limit falls below the lower bound of such confidence interval, the Control Rule would require that  new management measures reduce landings by the difference between the harvest estimate and the recreational harvest limit, but under no circumstances may such reduction exceed 40 percent.

If the 2023 recreational landings estimate tracks that of 2022, the landings estimate will probably be about 30 percent above the recreational harvest limit for 2024; whether the RHL will fall within or below the confidence interval for such landings estimate is anyone’s guess (we should also remember that the entire Harvest Control Rule/Percent Change Approach is being challenged in a federal lawsuit, and might possibly be invalidated by the court, adding another layer of unknowns to the issue).

Barring any big, unexpected change in the size of 2023 landings, anglers can probably expect to see new management measures, intended to reduce summer flounder landings by somewhere between 20 and 30 percent, in place for 2024.

We’ve seen reductions of that magnitude before.

The only difference is, in the past, such reductions were usually driven by excessive recreational landings, which occurred at a time when the stock was either expanding or, at worst, maintaining a stable level of abundance.  An increasing biomass, or a decrease in recreational landings, led to relaxed management measures after a year or two.

This time, 2022 landings fell well below both the commercial quota and the recreational harvest limit, yet overfishing still occurred due to a smaller than expected summer flounder stock.  No one knows why the stock isn’t expanding.  No one knows why recruitment has been low for over a decade, why summer flounder are growing more slowly, or why the stock has become less productive.

And no one knows when, or even whether, recruitment, or growth, or productivity will increase again.  The current situation could be here to stay.