STRIPED BASS DEJA VU: MANAGERS CONSIDER REVISED REFERENCE POINTS

 

About a quarter-century ago, after striped bass had recovered from their stock collapse, and both fishery managers and stakeholders were debating what that stock ought to look like in the future, some individuals, mostly representing the commercial fleet and the recreational fishing industry, supported a management approach that would truncate the age and size structure of the stock, in order to maximize harvest.

There were others, mostly recreational fishermen who spent most of their spare time on the water targeting striped bass, who argued that the best thing for both the fish and the fishermen was to keep fishing mortality low enough to allow a well-stratified age and size structure to develop, which featured a substantial number of older, larger, and more fecund females, in order to better insulate the stock against periods of low recruitment and to create what the anglers called a “quality” striped bass fishery.  They came together under the mantra of

“The job’s not done until we bring back the big bass.”

Things got heated, particularly as the Atlantic States Marine Fisheries Commission began holding hearings on what would eventually become Amendment 6 to the Interstate Fishery Management Plan for Atlantic Striped Bass.

Here in New York, there was a weekly saltwater angling publication that was handed out free at tackle shops, marinas, and similar places, which also maintained a popular website.  As New York’s Amendment 6 hearing drew near, the publication’s owner posted a poll on the website, asking whether readers would prefer to see striped bass managed primarily for harvest, with a population consisting mainly of small fish, and very few large ones, or whether they would prefer to see a population managed for larger fish, and a quality fishery, which necessarily meant lower landings.

His readers, by far, preferred managing for larger fish rather than for larger harvest, and he dutifully reported that preference at the hearing.

Immediately, New York’s recreational fishing industry retaliated, with tackle shops, for-hire boats, and at least some marinas cancelling their advertisements and threatening the publication’s survival, thus forcing the owner to recant and print editorials supporting industry positions.

Amendment 6 emerged somewhat better, adopting as its goal

“To perpetuate, through cooperative interstate fisheries management, migratory stocks of striped bass; to allow commercial and recreational fisheries consistent with the long-term maintenance of a broad age structure, a self-sustaining spawning stock; and also to provide for the restoration and maintenance of their essential habitat.  [emphasis added]”

Amendment 6 also included seven objectives intended to help achieve its stated goal, including

“Manage fishing mortality to maintain an age structure that provides adequate spawning potential to sustain long-term abundance of striped bass populations,”

and

“Establish a fishing mortality target that will result in a net increase in the abundance (pounds) of age 15 and older striped bass in the population, relative to the 2000 estimate.”

Unfortunately, the fishing mortality target finally adopted in the amendment represented a compromise between the harvest-oriented stakeholders and those more concerned with the age and size structure of the stock.  Amendment 6’s combination of generous commercial quotas and coastal recreational regulations that included a 2-fish bag limit, 28-inch minimum size and no closed season proved inadequate to constrain landings to anything close to the fishing mortality target.

The 2018 benchmark stock assessment found that, under the harvest regime established in the amendment, by 2017 the striped bass stock had already become overfished and was experiencing overfishing, while a presentation made at the February 2019 meeting of the ASMFC’s Atlantic Striped Bass Management Board revealed that overfishing had clearly taken place in 11 of the 15 years between 2003, when Amendment 6 was adopted, and 2017, while in two more years, the fishing mortality rate was just about equal to the threshold that defined an overfished stock.  Only two years out of the 15—2007 and 2009—saw a fishing mortality rate clearly below threshold, although even in those years, it appeared to be above Amendment 6’s fishing mortality target.

Yet even before the benchmark assessment was released, there were those on the Management Board who argued that, instead of reducing overfishing, the reference points that guided management actions—the target and threshold levels of female spawning stock biomass and fishing mortality—should instead be changed to accommodate what had long been deemed excessive harvest.

At the May 2018 Management Board meeting, in preparation for the next benchmark assessment, there was a long discussion of whether the reference points ought to be coastwide, or whether each spawning stock should have their own set of reference points.  There was also the question of whether the reference points should be “biological” reference points, derived from the stock assessment model, or whether the Management Board should continue to use “empirical” reference points based on observations and not the model itself.

In the end, biologists decided that the biological reference points derived from the model were “unrealistic,” and that empirical reference points based on the size of the female spawning stock biomass in 1995, the year that the formerly collapsed stock was declared fully rebuilt, would continue to be used.

But that didn’t end the reference point discussion.  At the May 2019 Management Board meeting, which focused on the then-anticipated Amendment 7 to the management plan, Maryland fisheries manager Michael Luisi again raised the question of moving the goalposts—that is, changing the reference points—in a way that reduced the spawning stock biomass target and made larger annual harvests possible, saying that

“We’ve had concerns over the reference points for quite some time.  In our mind they’re a bit too high.  I think they provide for an unrealistic expectation to the public that we’re going to achieve that level.

“You know, currently the threshold reference point is 91,000 metric tons and 125 percent of that puts us at a target value, and when you look at the estimates of spawning stock biomass that came out of the benchmark.  We have never achieved the target in all of that time as we’re evaluating that.”

Of course, Luisi was wrong about never achieving the biomass target, although he couldn’t know it at the time.  The 2022 stock assessment update made it quite clear that female spawning stock biomass was above the target level between 2002 and 2005, and just below the target in 2008, 2009, and 2010, a not unlikely result when fishing mortality remained below threshold for all but one of the years between 1982 and 2002.  The stock only began to decline after fishing mortality exceeded the threshold and the stock began to experience chronic overfishing.

And during those years when the stock exceeded the biomass target, the recreational fishery, which is responsible for most striped bass removals, was still allowed to harvest two fish per angler, with a 28-inch minimum size.

We can only speculate whether, had anglers already been constrained by the sort of regulations adopted in Addendum VI to Amendment 6 to the Atlantic Striped Bass Interstate Fishery Management Plan, with its one-fish bag and 28- to 35-inch slot size limit (without Addendum VI’s provision for conservation equivalency, which allowed states like New Jersey to legally skirt the rules), the spawning stock biomass might have climbed even higher, and might not have become overfished by 2013—or whether it ever would have become overfished at all.

As it happened, going into the debate over the Public Information Document for Amendment 7, options to change the reference points and the goals and objectives of the management plan were presented for public comment.  The public overwhelmingly rejected both suggestions, with 1,719 out of 1,747 comments addressing the issue—98.4%--opposing any change to the goals and objectives of the management plan, while 2,746 out of 2,764 comments—fully 99.4%--opposed changing the reference points to something that would, presumably, sacrifice the size and structure of the stock for a larger harvest.

Faced with that level of opposition, the Management Board wisely chose to remove any options to change the reference point or the goals and objectives from the draft of Amendment 7 that was finally sent out for public comment.

Yet, here we go again.

The ASMFC’s Atlantic Striped Bass Management Board will hold its next meeting at 1:15 in the afternoon of May 4.  One of the topics on its agenda is

“Discuss 2027 Benchmark Stock Assessment…

“Provide Guidance to Stock Assessment Subcommittee on Biological Reference Points and Spatial Management.”

The discussion will probably address two items that were highlighted in a January 26 memo from the Atlantic Striped Bass Stock Assessment Subcommittee to the Management Board, which was included with the meeting agenda.  The relevant item for this discussion is

“How does the Board want to balance preserving SSB and allowing fishing?”

As the memo explains,

“There is a trade-off between preserving SSB and allowing fishing, and determining the best balance between these two parameters requires management input.  If the Board wanted to establish a lower SSB target and threshold—for example, setting the target to the 1995 estimate of SSB and the threshold to some lower percentage of that value—then the F target and F threshold values could increase, depending on the assumptions about future recruitment.  Or the Board could set higher F target and threshold values based on a stable period in the fishery and calculate the SSB target and threshold values associated with those F rates in the long term, which would be lower than current values.”

In either case, striped bass abundance would decline.  As the memo noted,

“A lower SSB would mean lower availability of larger fish.  Even if the F target is increased, that may not translate into a higher harvest or yield, since that F rate is applied to a smaller population.  In addition, lower availability of larger fish means lower encounter rates overall, particularly in the ocean region.”

So, it would seem that a higher fishing mortality rate would be bad for the recreational fishery all around, as it would not only result in a smaller striped bass population made up largely of smaller fish, but it wouldn’t necessarily put ,pore fish in anglers’ coolers while lowering the encounter rate, and thus the overall quality of the fishery.

Nor would it seem to do the commercial fishery much good, since removing a greater proportion of fish from a smaller population probably wouldn’t result in significantly higher commercial landings.

And when the scientists on the Stock Assessment Subcommittee start saying things like

“If the Board is interested in considering options for a set of [biological reference points] with a higher F and lower SSB targets and thresholds, it would be helpful to receive inputs on things like…acceptable level of risk when it comes to preventing stock collapse…”

it might be past time to accept that making such changes to the reference points is a bad idea, given that we’re already worried that current levels of harvest and recruitment might be creating a risk of stock collapse that is higher than we’re comfortable with.

Yet it’s likely that there are some members of the Management Board—probably including most, if not all, of the delegations from Maryland, New Jersey, and Delaware, very possibly jointed by New York’s Governor’s Appointee—who will nonetheless want to include such possible changes in the 2027 benchmark assessment. 

That is not a good thing, but it is probably inevitable.  We will just have to deal with such proposed changes once the assessment is completed, just as they were dealt with in the runup to Amendment 7.

However, there are also changes to the reference points that might—and in some cases almost certainly will—emerge from the benchmark assessment itself.

At this point, I don’t know whether anyone is certain what model will be used to perform the benchmark assessment.  The biologists doing the work might utilize the same model that they used the last time around, but it is more likely that they will consider making some changes—examining the appropriateness of the model is, after all, one of the things that a benchmark assessment is for—in an effort to find a more accurate model, or at least one that is a better fit for the available data.

In the course of selecting the model, it is possible that they will select one that will generate biological reference points that aren’t deemed “unrealistic,” but instead provide useful guidance for the spawning stock biomass target, based on the productivity of the stock.  If that is the case, and managers can replace the current empirical reference points with a new set rooted firmly in striped bass biology, it will be a step forward, regardless of what the SSB target turns out to be.

We can only speculate about whether that might happen, but one thing is virtually certain:  If the benchmark assessment sticks with empirical reference points, and some version of the current model, the spawning stock biomass target and threshold will be reduced.  That’s not because of conniving, or any effort to increase striped bass landings, but rather because the current model uses recreational landings as one of its inputs and—perhaps counterintuitively—higher recreational landings generally lead to a higher estimate of SSB.

We saw that in the last benchmark, when the use of Marine Recreational Information Program landings estimates, which were significantly higher than those provided by the obsolete Marine Recreational Fishing Statistical Survey, led to a substantially higher estimate of spawning stock biomass.  But now, the National Marine Fisheries Service has determined that MRIP overestimated the number of recreational fishing trips, and thus recreational catch, releases, and landings.  Since 2023, NMFS has been working to correct flaws in the survey and revise the data accordingly, a process that is expected to be completed later this year.  The revised data, which will include lower estimates of recreational landings, will be available in time for the benchmark assessment and, unless a new model dictates otherwise, will result in the estimate of spawning stock biomass being revised downward as well.

The spawning stock target will be revised accordingly, as will the fishing mortality reference points.

And that will be good, as it will bring the reference points into alignment with the best available science.

As to any other proposed change to the reference points?  We’ll just have to wait and see.