BLACK SEA BASS ASSESSMENT LEADS TO UNNECESSARY CONSTERNATION

 

On Wednesday, August 14, the Mid-Atlantic Fishery Management Council and the Atlantic States Marine Fisheries Commission’s Summer Flounder, Scup, and Black Sea Bass Management Board will meet in joint session to, among other things, consider 2025 specifications for the recreational and commercial black sea bass fishery.

It promises to be a contentious meeting.

Late last year, the Northeast Fisheries Science Center released a research track stock assessment for black sea bass.  A research track assessment (similar to what the ASMFC calls a “benchmark stock assessment”) is intended to take a new look at the management process, and attempts to address particular issues and/or explore new scientific models, in order to better understand the dynamics of the fishery.  In this case, the research track black sea bass assessment ended up adopting an entirely new assessment model, the Woods Hole Assessment Model (WHAM), replacing the Age Structured Assessment Program (ASAP) model previously used.

The new research track assessment passed peer review, and so represents the current state of the art in black sea bass management.  It managed to largely eliminate what had been a significant retrospective pattern in the previous assessment, which overestimated fishing mortality and underestimated spawning stock biomass in the northern region (that is, north of Hudson Canyon), while at the same time underestimating fishing mortality and overestimating biomass in the southern region.  That in itself was a significant improvement.

However, while the research track assessment provided a new approach to assessing the black sea bass stock, its findings did not directly translate into fishery management measures.  Instead, the methodology of the research track assessment was then incorporated into a management track assessment (similar to what the ASMFC calls a “stock assessment update”) that determined the status of the stock through the end of 2023, and will be used by the Council and Management Board to set 2025 management measures.

Once the management track assessment was completed, the Council’s Scientific and Statistical Committee must set the Allowable Biological Catch, which establishes the upper limit for catch—that is, the combined landings and dead discards of both the recreational and commercial fleets—as the Magnuson-Stevens Fishery Conservation and Management Act dictates that each regional fishery management council must

“develop annual catch limits for each of its managed fisheries that may not exceed the fishing level recommendation of its scientific and statistical committee or the peer review process established”

elsewhere in Magnuson-Stevens.

The Council’s Scientific and Statistical Committee met on July 23-25 to address black sea bass and a number of other species; an Executive Summary of the meeting, released on August 7, noted with respect to black sea bass that,

“The 2024 [management track] assessment in June represented the first implementation of the new modeling paradigm and its use for deriving Biological Reference Points and projections.  The SSC appreciated the conceptual advances, but noted that many of the model features are not easily compared to previous models, particularly fishing mortality reference points.  As in previous models, the stock is not overfished and overfishing is not occurring.  The stock biomass is more than twice the B_msy level and expected to decline towards the biomass target in the short run, but not as quickly as previously thought.  Another [management track assessment] will be conducted in 2025 to get specifications for 2026 and 2027.  (The shortened interval between is a result of a management need to synchronize specifications among the other stocks in the Fishery Management Plan.)  An OFL CV of 150% was used, primarily due to the uncertainty associated with MRIP estimates of recreational removals.  The SSC recommends an ABC of 6.027 [metric tons] for 2025.”

Given that the Acceptable Biological Catch for 2024 was 7,557 metric tons, and that the 2025 recommendation was about 20 percent lower, the SSC’s decision made a lot of people unhappy.

While that unhappiness is understandable, as black sea bass remain one of the most abundant inshore species, particularly in New England and the upper mid-Atlantic, reading both the 2021 management track assessment, which was based on the no-longer-used ASAP model, and the 2024 management track assessment, helps to explain why landings must be reduced in 2025.  In addition, with respect just to the recreational fishery, it’s easy to argue that landings probably should have been reduced by 10 percent in 2024, and that any 2025 reductions that may occur will merely serve as a delayed substitute for measures that should have been adopted a year ago, and don’t even begin to account for the lowered estimate of the spawning stock biomass target.

The ASAP model that was formerly used to assess the black sea bass stock had set the biomass target at 14,092 metric tons; the actual spawning stock biomass was about 220 percent of that target, or roughly 31,000 metric tons.  When the assessors switched to the WHAM model, the estimate of SSB_target dropped to 11,225 metric tons, and 219 percent of that number is only a little over 24,500 metric tons—about 20 percent less.  Such smaller biomass estimate means that, to prevent overfishing, harvest has to be reduced accordingly, as the estimate of maximum sustainable yield fell from 4,773 metric tons to 3,649 metric tons—again, by a little over 20 percent.

In that context, a harvest reduction of 20 percent seems completely reasonable.  It’s not that the new ABC is being set too low,  as some people claim, because of questionable estimates of recruitment, past fishing mortality, future landings, or any other, similar factor; instead, the old ABC, used in the 2021 management track assessment, was set too high, and probably allowed too many black sea bass to be caught in previous years.  The 20 percent reduction in ABC merely amounts to a reset, which aligns catch with what is now considered the best estimate of spawning stock biomass.

Yet too many people hear the word “reduction” and then hear nothing else, but instead have a knee-jerk reaction to oppose harvest cuts without even trying to understand why such cuts might be needed.  That was clearly the case at the August 5 Advisory Panel meeting, where

“Advisors were very frustrated with the 20% decline in the 2025 black sea bass acceptable biological catch (ABC) limit recommended by the Council’s Scientific and Statistical Committee (SSC) compared to the 2024 ABC.”

At the meeting,

“Several advisors questioned the accuracy of the biomass projections which inform the ABC…One advisor said it feels as if the ABC needs to be cut by 20% just in case recruitment is worse in the future…Several advisors said the current stock projections should not be used in management as the numbers don’t make sense and there is not a comprehensible explanation for why biomass is projected to decline rapidly.”

I’ll be the first to admit that the 2024 management track assessment was a bit sparse, and didn’t provide a particularly clear explanation for why various values had changed significantly since 2021.  Like others, I was a bit puzzled by the assessment's conclusions.  However, instead of merely rejecting the assessment and the advice of the SSC, I took the time to inquire as to why the WHAM seemed to produce such different results.  A biologist from the Northeast Fisheries Science Center provided an explanation:

“The model from the 2024 management track still exhibits the strong year classes in 2011 and 2015, however the magnitude is a bit less.  This is probably owing to our new understanding of the recruitment process in the WHAM model.  These models allow us to include more variability in processes like recruitment, survival, and selectivity, such that these models can have more flexibility to better reflect the actual underlying population dynamics.  There are many additional features in the WHAM model…compared to the ASAP model…that we think better reflect reality—the use of a single fisheries independent index that doesn’t ‘chase noise’ of several fisheries independent indices with small spatial footprints and a selectivity pattern for the recreational fishery in the North that more accurately reflects the size limits that changed over time.  The lessened magnitude of those recruitment spikes does mean the SSB has a consequential increase in the following years…in 2017-2018.  However, both models end up with SSB in the same place in 2019, they just have different explanations for how the stock got there.  The changes in [maximum sustainable yield] and target [spawning stock biomass at maximum sustainable yield] are likely because of our changed perception of SSB…”

A lot of that could probably be summed up by saying, “We thought that the spawning stock biomass was larger than it actually was; now that we know better, we had to revise some of our estimates downward to reflect our current understanding of reality.  Although such summation wouldn’t capture all of the nuances, it would be close enough to provide a better understanding of why the 20 percent reduction was needed—at least to those folks who had any desire to actually understand, and not merely fight for the status quo.

One of the more remarkable aspects of the discussion was that those representing the recreational sector seemed unaware of how the recreational black sea bass fishery was actually managed, and that, because of the so-called “Percent Change Approach” adopted by the Council and the ASMFC’s Interstate Fishery Management Plan Policy Board in June, 2022, the biggest reduction in landings that anglers might experience in 2025 is just 10 percent—and that’s the worst case, because depending on how the numbers turn out, anglers could even get a small landings increase.

That’s because, right now, black sea bass are considered a “very abundant” species, with spawning stock biomass more than 150 percent of the target level.  Thus, Council staff would calculate whether, if 2024 management measures were carried over into 2025, there would be at least a 90 percent probability that recreational landings would exceed the recreational harvest limit.  If the answer to that question was yes, then management measures that would reduce 2025 landings by 10 percent compared to 2024 would be imposed.  However, if the 90 percent confidence interval (essentially, a “margin for error” above and below the point estimate of 2025 landings, calculated so that there is a 90 percent chance that the actual value of 2025 landings would fall somewhere within the specified range of values) overlapped the 2025 recreational harvest limit—something that it not beyond the realm of possibility—recreational landings would be increased, rather than reduced, by the same 10 percent.

Pursuant to the "Precent Change" process, 2024 black sea bass landings should have been reduced by 10 percent, compared to landings in 2023.  However, because competing priorities at the Northeast Fisheries Science Center delayed completion of the management track assessment by one year, and because the Percent Change Approach was intended to be used in conjunction with a recent stock assessment that was not yet available, no reduction in 2024 landings occurred.  Thus, even in the worst case scenario, which sees a 10 percent landings reduction in 2025, the recreational sector will be no worse off than they would have been had the most recent management track assessment been completed in time for the current season.

Given such circumstances, the recreational sector, in particular, has little reason to complain if it must ultimately face a 10 percent harvest reduction in 2025.  Yet not only complaints, but misinformation, is rife.  A recent column in the [Delaware] Cape Gazette is a prime example, where the author complained that

“Our dear friends at NOAA have once again done the unbelievable.  With the population of black sea bass at 219% of the biomass target, they are calling for a 20% decrease in the recreational catch to prevent overfishing.  You read that right:  They want to cut our catch by 20% to prevent us from overfishing a stock that is 219% above the biomass target.  Please let that sink in for a moment.”

Such overblown rhetoric serves no one, except perhaps the handful of people that might profit from overharvesting sea bass in the short term.  It creates antipathy toward fisheries managers and management bodies that are merely trying to execute their obligations under federal law.  And factually, it is just plain wrong.

As noted above, there is no way that 2025 recreational black sea bass landings will be reduced by 20 percent, so long as the Percent Change Approach remains in effect.  The greatest possible reduction will be 10 percent, and a 10 percent increase in landings is not completely out of the question.

The article confuses the notion of a stock being at 219 percent of the target level with that of a stock being 219 percent above such target—which would denote a stock 100 percentage points larger than it actually is.

It suggests that fisheries managers are imposing a reduction on their own initiative, rather than merely carrying out the requirements of the management plan and federal law.

And perhaps worst of all, it makes no serious effort to explain why the 2024 management track assessment might lead the SSC, council staff, or those charged to interpret federal law to believe that a reduction is required.  It is intended only to spawn outrage.

And outrage is a funny thing, because there are a lot of people, in the recreational fishing industry and in the angling press, who get outraged when landings are cut.  But it’s hard to recall a time when many of the same writers and industry members were outraged because managers allowed striped bass to become overfished once again, did nothing to protect the winter flounder when stocks began to decline, or allowed New England cod stocks to collapse.

Which probably says more about their current outrage than you will ever need to know.