STRIPED BASS: IS IT TIME TO CHANGE FOCUS?

 

Since the 2013 benchmark stock assessment told us that striped bass spawning stock biomass and fishing mortality were both headed in the wrong direction—and maybe even since the 2011 stock assessment update predicted that the stock would become overfished by 2017—responsible striped bass anglers have focused on reducing fishing mortality and rebuilding the striped bass stock.

That focus only intensified in 2019, after the most recent benchmark assessment revealed that the striped bass stock was both overfished and experiencing overfishing.

But now we have a stock assessment update—it will be formally revealed at tomorrow afternoon’s Atlantic Striped Bass Management Board Meeting, but has been publicly available for about ten days—which informs us that overfishing has not only ended, but that the fishing mortality rate in 2021 was a mere 0.14, below the F=0.17 target.  While the assessment finds that the stock remains overfished, it predicts that if overfishing doesn’t recur, the stock will rise above the spawning stock biomass threshold, which defines an overfished stock, at some point in 2023; if the fishing mortality rate doesn’t exceed the 0.17 target, it is more likely than not that the stock will be fully rebuilt by 2029.

Admittedly, there is some uncertainty built into the assessment update, and there remains a substantial chance—48% at F=0.17, 21% at F=0.14—that the stock will not be rebuilt by that deadline.  However, a benchmark assessment scheduled for 2024 and an update a few years later will provide the Management Board with opportunities to put rebuilding back on schedule should it begin to veer off track. 

Even assuming the worst case, and a stock that isn’t rebuilt by the deadline, managers have already ended overfishing and reversed the long decline in the female spawning stock biomass, which are both positive steps.  If the rebuilding effort falls short of attaining SSB_target by 2029, it’s not likely to miss by much.

Taken together, that’s pretty good news.  It may lack the absolute certainty we want to hear, assuring us that the stock will be fully restored by 2029, but if you’re looking for absolute certainty, you probably shouldn't get involved with fisheries management.  The science is pretty good—and in the case of striped bass, it’s far better than that—but Mother Nature can be capricious, and some uncertainty always remains.

Even so, far too many striped bass anglers remain focused on rebuilding.  Since the stock assessment update, with its prediction that the stock is likely to rebuild under current regulations, was released, there has been a wave of angler complaints and comments attacking the assessment, those who performed it, and the Atlantic States Marine Fisheries Commission as a whole; many recreational fishermen are unwilling to accept the scientific advice, and refuse to believe that the stock can be rebuilt without further reductions in fishing mortality.

I’ll admit that, at the gut level, I share some of their doubts.  Looking at the data presented in the benchmark assessment, knowing what I see on the water, and talking to a lot of experienced anglers who fish between Maine and the Chesapeake Bay, I expected that fairly massive harvest reductions would be needed to achieve rebuilding by the 2029 deadline. 

In fact, when preliminary information coming out of the Atlantic Striped Bass Technical Committee and Stock Assessment Sub-Committee seemed to suggest that a fishing mortality reduction somewhere in the 25% range would be needed to rebuild the stock, I felt a sense of relief, as such a reduction was probably close to the limits of what was politically and practically doable.

When I heard that the folks preparing the update determined that no management changes were needed to achieve the rebuilding goal, I was immediately taken aback.  But after having the opportunity to read the draft update, and to ask the assessors questions during one of their meetings, I understand how they came to their conclusions and why such conclusions make sense.

That doesn’t mean that I’m completely convinced that the stock will be rebuilt by 2029.  Uncertainties remain, and those uncertainties aren’t trivial.  But there seems to be little doubt that the stock will be in much better condition in 2029 than it is in today.

So, unlike other striped bass anglers, I’m not really focusing on 2029 anymore.

I’m more concerned about what happens after 2030, when threats to the striped bass stock, which might be far more damaging and harder to fix than past overfishing or missing a rebuilding deadline, could easily arise.

Ending overfishing and rebuilding overfished stocks are, in most cases, less scientific problems than political issues.  It’s not that managers don’t know how to get the job done, it’s just that they don’t always want to endure the public abuse and political pressure that always accompanies efforts to conserve fish stocks by reducing harvest.  

It doesn’t really matter what fish are involved, or what sector is most affected; impose more restrictive management measures, and someone—either commercial fishermen, anglers, or the for-hire fleet, and often some combination of the three—is not only going to complain, but will put up a spirited fight in the press, at public hearings, and perhaps even at the legislative level.

But if managers are allowed to do their jobs, they know how to end overfishing and put overfished stocks on the road to recovery.  It’s not so simple when the problems besetting a stock aren’t caused primarily by people, but by nature.  

While the ASMFC, acting through the states’ fishery management agencies, has the ability to impose its will on fishermen, it has no similar ability to dictate environmental conditions in the spawning rivers, and it is those conditions that have proven to be the primary determinant of striped bass spawning success.  Cold, wet winters followed by cool, wet springs tend to produce large year classes, while warm winters followed by early, dry springs lead to below-average spawns.

In recent years, the latter sort of weather has prevailed, and as the climate warms, such conditions may become even more common.

Over the past four seasons, the Maryland Juvenile Abundance Index, historically the most reliable predictor of future striped bass abundance, averaged just 3.16, as compared to the long-term average of 11.3.  The recent mark tied the average for the years 1983-1986, when the stock was just beginning to recover from its earlier collapse; there has not been a lower four-year average in the 65-year history of the Maryland juvenile abundance survey.  The period 2019-2022 also marks the first time in history when the Maryland JAI failed to rise above 4.00 for four consecutive years.

Right now, the striped bass stock can be rebuilt to, or at least close to, its target by 2029 because of the large 2011 and 2015 year classes, and the somewhat above average 2017 and 2018 year classes, that have already been produced.  Because female spawning stock biomass is measured in metric tons (which are generally converted to pounds in ASMFC documents) as those fish grow larger, such biomass will naturally increase, even if there are fewer overall fish in the population; given the slot limit, there shouldn’t be many removals of fish over 35 inches in the future, something that should allow the spawning stock biomass to increase more quickly, even as abundance declines somewhat.

We’re already seeing that occurring.  In 2019, female spawning stock biomass was estimated at 56,634 metric tons, while overall abundance was estimated to be 263.7 million fish; two years later, spawning stock biomass had increased to an estimated 64,805 metric tons, while overall abundance decreased to 218.9 million individual striped bass.  Those diverging trends seem counterintuitive to many anglers, but make perfect sense:  Bigger, older bass weigh more.

However, the trends can’t diverge forever.  Bass of every age and size are removed from the population each year, and there will come a time when diminishing numbers of individual fish also cause the biomass to decline.

When that will occur, and even if it will occur, can’t be determined now.  A good spawn over the next year or two can reinforce the spawning stock biomass and prevent future decline, at least for a while.  But if that good spawn doesn’t occur…

Striped bass can live for at least 30 years, so in theory, fish from the 2011 and 2015 year classes will still be around in the early 2040s.  As a practical matter, both natural and fishing mortality will have so whittled away their numbers by then that they will make up only a very small fragment of the spawning stock.  For management planning purposes, it probably makes more sense to assume a 20-year lifespan—and even that might be high; a 50-pound bass is about 20 years old, and there aren’t that many 50s still swimming around.  But assuming a 20-year lifespan, we can figure that the contributions of the 2011 and 2015 year classes will quickly taper off after the early 2030s—right after the stock is scheduled to be rebuilt.

What happens then?

So far, it seems nothing good.

Over the past decade, the average for the Maryland JAI was 8.38, a little below average, even with the large 2015 year class included; the average for the seven years after 2015 is an even lower 6.12. So beginning just after the stock is, hopefully, rebuilt, the stage is being set for a decline in abundance.

From a recruitment perspective, that doesn’t matter too much.  Successful recruitment isn’t dependent upon a large spawning stock; there is virtually no relationship between the numbers of spawners and the success of the spawn. 

Having said that, it’s still necessary to have some adult bass around for recruitment to occur.

With recent recruitment well below average, future recruitment unpredictable, and a changing climate more likely to usher in conditions unfavorable to successful spawns, it’s probably time to stop focusing on what the striped bass stock will look like at one discreet point in time—that is, whether it will be rebuilt in 2029—and start to take a longer, more extended view, and consider what it will take to maintain a healthy and sustainable striped bass stock well into the future.

If managers do that, they may well find that the current regulations, although sufficient to rebuild the stock, will not be sufficient to maintain it at healthy levels if recruitment does not improve soon. 

If that is the case, it is probably time to start considering more conservative management, that will increase the proportion of fish that survive to older ages, before too many fish from the successful year classes are removed from the stock.  Or, managers can maintain the existing regulations, and hope that a good year class will eventually come along.

I’ve always liked the expression, “Hope is not a plan.”