STRIPED BASS AMENDMENT 7--ITS PROMISE AND PERILS: PART II, REBUILDING THE STOCK

To put it bluntly, a fishery management plan that, because of how it is written, fails to prevent overfishing, fails to maintain spawning stock biomass at a level likely to assure the long-term health of the stock, and fails to provide for the prompt rebuilding of such stock should it become overfished isn’t worth the paper that it’s written on.

And any management body that tolerates such a plan, and makes no effort to correct its flaws, is derelict in its duties to both the resource and to the public.

Thus, it is good that, at the October meeting of the Atlantic States Marine Fisheries Commission’s Atlantic Striped Bass Management Board, such Board voted to include a rebuilding provision in the most recent version of the Draft Amendment 7 to the Interstate Fishery Management Plan for Atlantic Striped Bass.  Such action followed another commendable action at the Board’s previous meeting, when it tasked the Plan Development Team with devising ways to protect the large 2015 striped bass year class, in order to facilitate such rebuilding.

Both of those topics have been addressed in the latest version of the Draft Amendment, and both will be discussed in today’s edition of One Angler’s Voyage.  The discussion will be a lot shorter than the one addressing the management triggers, but the issues are complicated enough to deserve a thorough review.

Because rebuilding, and then maintaining, healthy fish stocks should be the primary goal of any management effort, we’ll take a look at that issue first.

Rebuilding the stock by 2029

The current version of the Draft Amendment acknowledges that

“Rebuilding the Atlantic striped bass population will enhance the economic and social benefits attributable to this population in the ASMFC member states.  Economic benefits of a rebuilt stock would include increased use values (e.g., consumptive and non-consumptive use values related to commercial and recreational fishing) and non-use values (e.g., existence values) for current and future generations…potential changes [to management measures] may result in short-term negative impacts to recreational angler welfare.  However, the net positive long-term social and economic benefits stemming from stock recovery and subsequent catch increases in successive years will likely outweigh the short-term impacts.”

Thus, rebuilding the population should be the Management Board’s first priority when considering the impacts of Amendment 7.  There are undoubtedly a number of Management Board members who won’t see things that way, particularly because the management plan calls for rebuilding the stock within 10 years, a deadline that is now being interpreted as 2029.  

By the time a rebuilding plan is put in place, it will have only 5 years to get the job done. 

Despite that, the draft amendment has so far been faithful to the 10-year timeline.  It clearly states that

“The 2018 benchmark stock assessment indicated the striped bass stock is overfished and experiencing overfishing relative to the updated reference points defined in the assessment.  By accepting the assessment for management use in 2019, two management triggers were tripped requiring the Board to take action to address both the overfishing and overfished status determinations…To address the overfished status, the Board must adjust the striped bass management program to rebuild the [spawning stock biomass] to the target level in a timeframe not to exceed 10 years, no later than 2029.”

The Draft Amendment never suggests that rebuilding can be avoided or deferred, or that a longer rebuilding timeframe could be adopted.  However, the Management Board retains the power to alter the Draft Amendment’s language, so those things all remain possibilities. 

However, for purposes of next week’s meeting, the question is not if a rebuilding plan will be put in place—it will be—but how any necessary rebuilding measures will be calculated.  The Draft Amendment includes two options.  As such draft explains,

“The Board has expressed concern about recent low recruitment rates and the potential impact of low recruitment levels on the ability of the striped bass stock to rebuild by no later than 2029.  Several years of poor recruitment may indicate the stock is entering a low recruitment regime, and levels of recruitment that were sustainable during average or above average recruitment regimes may not be sustainable in the future.

“[The fishing mortality rate required to rebuild the stock] could be calculated by drawing recruitment from the values observed from 1990 to the terminal year of the stock assessment (i.e., the standard recruitment method used in the striped bass stock assessment).  However, if recruitment is drawn from a below-average period instead of the period from 1990-forward, for example, [the fishing mortality rate required to rebuild the stock] would be lower.  If the population is fished at [a fishing mortality rate intended to rebuild the stock] using the standard recruitment method but average recruitment remains lower than the time series mean, the population might not be able to rebuild to the [spawning stock biomass target] by 2029.”

Thus, picking the right recruitment rate is an important part of the rebuilding process.  To put it in a real-world context, the average Maryland juvenile abundance index for the years 1990-2021 is 14.16, somewhat above the long-term average of 11.4.  On the other hand, if recruitment for the years 2007-2020, identified by the Plan Development Team as a low-recruitment period, are used, the average Maryland juvenile abundance index would be 10.18, slightly below average.

Although that’s not exactly the way the Atlantic Striped Bass Technical Committee would calculate rebuilding measures—they would very probably use the numbers of Year 1 fish recruiting into the population each year, rather than juvenile abundance estimates—it’s clear that the years picked will have a significant impact on the success of any rebuilding plan.

Thus, the Draft Amendment’s section 4.4 REBUILDING PLAN offers two options.  The first, designated Option A, would use the standard method of calculating recruitment when preparing the rebuilding plan.  Option B is more conservative, and would calculate recruitment based on the lower recruitment that occurred in the period 2007-2020.

Given that the last three years saw the Maryland juvenile abundance index return values of 3.37, 2.48, and 3.20, adopting Option B would seem to be the more prudent approach.  But I say that knowing that striped bass recruitment is highly variable, and largely dependent on environment conditions in the rivers when and where the spawning takes place. 

If the current cold continues this winter, and we have a nice, rainy spring, 2022 could produce the highest juvenile abundance index in the past 20 years.

Or it might not.

There’s no way to be sure.

The one thing that we can be sure of is that any rebuilding plan based on low recruitment will need to include very restrictive management measures if it is to succeed.  Measures so restrictive that I expect many Management Board members to either try to defer the rebuilding deadline or try to remove the rebuilding provision from the Draft Amendment.

I also expect that there will be enough Management Board members concerned about the future health of the striped bass stock that any effort to do the latter, at least, will not succeed.

Until there is hard evidence to the contrary, Option B seems the right way to go, although there’s no compelling reason for the Management Board to delete either one before approving the Draft Amendment.

Protecting the 2015s (and perhaps the 2017s and 2018s, too)

I believe in, and am constantly calling for, science-based fishery management, whether the species being managed is striped bass or something else.  Most of the folks I know who are involved in fisheries issues say that they want the same thing.

That means that we ought to accept scientists’ findings, even when they seem counterintuitive or are contrary to our expectations.

Thus, none of us ought to put up a fuss when we learn that the Plan Development Team, after consultation with members of the Technical Committee, has recommended removing protections for particular year classes from the Draft Amendment.  In doing so, the PDT said,

“The PDT is recommending that the Board remove [options to protect the 2015, 2017, and 2018 year classes] from consideration in Draft Amendment 7…

“…Stock projections for [the various options] indicate the stock recovery timeline (i.e, the year the [spawning stock biomass] is projected to exceed the threshold and the year the [spawning stock biomass] is projected to exceed the target) is the same as the stock recovery timeline under Status Quo.”

At first glance, that might not sound right, but it all comes down to killing fewer fish.

Protecting a few larger year classes does not, in itself, reduce landings.  It merely shifts angling effort onto other year classes, which would then make up most of the harvest (lacking any way to accurately calculate how anglers will respond to changing size limits, managers must assume that effort will remain constant despite any regulatory change).  Thus, to rebuild the stock, it's not enough to protect one part of an otherwise fishable population; management measures must allow more fish, regardless of year class, to survive, if the  spawning stock biomass is to increase.

As always, things aren’t quite that easy.  One might argue that shifting effort off the older, larger fish, that produce larger, more viable eggs and more viable larvae, might result in a greater benefit than protecting first-time spawners.  But one might also argue that allowing too many of the younger spawners to be killed puts the future of the stock at risk, since the older, larger bass won’t live forever; their ranks are constantly waning, and can only be maintained by allowing smaller fish to grow large.

A few of the size limit options considered did seem to provide some benefit.  A one-fish bag limit and 35-inch minimum size on the coast, coupled with a 2-fish bag and 18- to 23-inch slot in the Chesapeake Bay, seemed to offer the greatest protection, but such measures' benefits were still so small that they weren’t statistically meaningful, and fell within the confidence intervals—what we might think of as the margin for error—of the scientists’ calculations.  

Other options, besides the status quo, included a one fish bag and either a 32- to 40-inch slot limit or 28- to 32-inch slot limit on the coast, and a one-fish bag and 18- to 28-inch slot in the Chesapeake Bay.  None of those provided as much benefit as the 35-inch coastal minimum or 18- to 23-inch Bay slot, which themselves didn’t do enough to  merit adoption, and so the alternatives aren't worth further discussion.

I have to admit that, in my gut, I hate to see the year class protections taken out of the Draft Amendment.  But good fishery management isn’t driven by gut reactions—we’ve gotten into far too much trouble that way—but by good science conducted by competent professionals.  And since that sort of science is what led to the recommendation that the year class protections ought to go, then we need to be good with that.

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Nest Thursday—just six days ahead of the Management Board meeting—I’ll address the final issues, conservation equivalency and efforts to reduce recreational release mortality.