There Is a Striped Bass Stock-Recruitment Relationship

This blog should give you hope amidst a flurry of rightfully pessimistic calls for management reform. Striped bass are insanely resilient; at a level we don’t appreciate. They hit rock bottom three decades ago and bounced back as soon as we halted the slaughter. We reopened harvest and have overfished the stock since. The data upon which the stock is managed (MRIP) is a disaster. The Striped Bass Board in charge of their management is a bigger disaster. Among their lengthy résumé of missteps is allowing the commercial sector to gillnet giant females coming into the spawning tributaries. Possibly the biggest mistake in this catastrophe is that ASMFC has managed the striped bass stock under the assumption that there is no relationship between the number of fish in the water and how successful the spawn is. That dynamic is referred to as the “stock-recruitment relationship”. Managers decided a bigger stock does not equate to more recruitment. This decision has never sat right with conservationists. Even in the face of this ignorance, these incredible fish persist.

The harsh reality of the current state of the fishery is a result of a never-ending assault, substandard management and scientists who are adept at mental gymnastics to avoid accountability for their past reckless decisions. All that said, we hope this blog will give you hope. Join us for a dive into the reality of the “striped bass stock recruitment relationship”, where we dispel one of the biggest myths holding back striped bass conservation progress.

That’s right. It does matter how many big old females are in the water. Truthfully, if there is a silver bullet out there, protecting the big females may be it. This fishery will bounce back to the glory days if managers actually keep more fish in the water. That’s a promise.

Our position is simple: the size of the spawning stock matters. The decision that there is no stock recruitment relationship (It doesn’t matter how many sexually mature females are in the system) was 100% subjective and not ecologically honest. It didn’t fit into the model, or so that was the reasoning. It was not based on fact. The reward of denying the relationship is evident: more opportunity to harvest the big fish if the “science says they’re not that important.”

As a reminder, the Chesapeake Bay produces anywhere from 70-90%+ of all baby striped bass any given year. The spawning record from the Bay shows the relationship plainly, and the stock assessment’s own lead scientist has said on the record that the relationship exists. In our view, management hasn’t acted as if it does. So, let’s make it clear: there is absolutely a stock-recruitment relationship for Atlantic striped bass. And if we ever lower the target (to which the stock is managed), we may never get a good spawn again. As the data below shows, larger numbers of spawning females can perform well, even with “unfavorable” environmental conditions. If the spawning stock biomass (SSB) is small, the fishery can’t even foster an average spawn, no matter how favorable the conditions.

An individual’s perspective of the fishery does not alter the ecological reality. If you are concerned about the impact of climate change on striped bass, the only solution is to make sure more stripers are in the water. If you’re concerned about the variable weather conditions of a given year, just make sure more stripers are in the water. It is really that simple. Concerned about anything? Keep more fish in the water – and our research below proves that beyond a shadow of a doubt.

The information below will change the trajectory and mismanagement of striped bass. Recruitment failure isn’t explicitly caused by climate change, habitat degradation, or some other external mysterious force; it’s happening because we manage this resource terribly and kill too many fish. They let fishing mortality run rampant over the F-target from 1995-2020 and peaked at over double the F-threshold. That’s why the SSB has been below the threshold since 2013. Overfished SSB results in spawning failure.

As an avid striped bass angler, do you want to spend every year praying for perfect spawning conditions, or do you want to maintain a healthy, sustainable striped bass fishery? Do you want a 0% chance or a 25% chance for success? For every pound we lower the SSB target, we cut the chances for a spawn to produce the YOY index (young of the year, how spawning production is measured) that every angler is praying for. Anyone who says “lower that target” is just saying, “Let us keep killing, and we don’t give a damn about the future. We want what we want now.”

We need to stop asking how low the spawning stock can go and still produce a decent year class. We need to start prioritizing how to keep it high enough that it always can.

What the stock assessment actually says

The 2019 benchmark stock assessment, the science behind today’s management, says this: “Based on literature reviews and committee opinion, the Beverton-Holt equation was selected as the appropriate stock recruitment relationship for striped bass. Internal model fits of this relationship were poor and so recruitment is estimated as a log-normal deviation from average recruitment.”

The scientists picked a stock-recruitment curve as the right one for striped bass. Then they couldn’t fit it inside their model, so they set it aside. Recruitment in the model is treated as random bounces around an average. That is a subjective modeling decision. It is not a finding that spawners don’t matter. Read that again. The reason why they told us there was no relationship was because it didn’t fit into the math formula.

The 2013 assessment went the same way. It moved away from stock-recruitment curves “because of the sensitivity to the stock-recruitment model.” Today’s spawning biomass reference points are pegged to the 1995 stock, and the reference point and rebuilding projections draw future recruitment from the 2008 to 2023 low-recruitment years, with no link to how many spawners are out there.

At the May 2026 Board meeting, New York commissioner Emerson Hasbrouck asked ASMFC Stock Assessment Team Lead Dr. Katie Drew about this directly. Her answer: “There is clearly some kind of stock recruit relationship, right. If you don’t have spawning stock biomass you won’t get any recruitment.” She went on to explain the two real problems: the environment drives a lot of the year-to-year swings, and the reference points get very sensitive to small changes in how the curve is fit. When Hasbrouck followed up and asked whether there is a minimum spawning stock needed to make a good year class in a good spring, she said her team had not looked at that and added: “I think we do have a fairly decent history of extremely low SSB and extremely low recruitment. Can we parse that apart from the environmental effect that we’re seeing? I don’t know, but that is something we can look into a little more with this assessment.” Our Association is done waiting for scientists and managers to do their jobs while the fishery spirals towards the brink. So, we went ahead and assessed the data ourselves.

Yes, the stock-recruitment relationship exists. Yes, it is hard to pin down with a formula. These are two independent statements. We believe management has been acting as if only the second one is true.

Let’s look at that history of low spawning stock and low recruitment.

Zero for seven

Every year with spawners under 66 million pounds was below average, wet spring or dry.

The stock assessment estimates female spawning stock biomass every year back to 1982. Maryland DNR has counted young-of-year striped bass in the Bay every summer since 1954. Line the two up for the 1982 to 2023 spawning years and one result jumps out.

In the seven years when female spawning biomass was under 66 million pounds, the Maryland juvenile index never once reached its long-term average of 10.8. Not one time in seven.

Now the other end. In the 15 years when female spawning biomass was over 198 million pounds, the index hit average or better eight times.

Zero of seven against eight of 15. The four biggest year classes in the record, 1996, 2001, 1993 and 2011, all came from female spawning stocks of 160 million pounds or more. That is roughly five times the mid-1980s level.

Big spawning stocks can beat dry water. Small ones couldn’t use the best water.

The obvious objection is that the 1980s were just bad years for the Bay. The weather doesn’t back that up, at least not for the best springs of the decade.

River flow in spring is one of the things the research ties most closely to young-of-year success. Split the 1982 to 2023 spawning years into wet springs and dry springs, using average Susquehanna River flow from February through May (above or below the 1968 to 2025 median of about 60,700 cubic feet per second), and set them against the size of the spawning stock. A good year class here means a Maryland index at or above the 10.8 long-term average.

The bottom right cell is important. In dry springs, the kind the research links to weaker year classes, big spawning stocks still produced an average or better year class two times out of eight. One of those was 2001, a dry spring that produced a Maryland index of 50.75, the second biggest in the 42 years. The other was 2007, at 13.39. Dry springs still hurt: the other six dry high-spawner years fell short.

Now read the top left. With few spawners, the best water in the record produced nothing. By our count, 1983 and 1984 were two of the best Chesapeake springs of the last four decades. We ranked every spring from 1982 to 2023 on river flow and temperature together. 1984 ranked 2nd of 42. 1983 ranked 5th. Those springs produced Maryland indexes of 4.21 and 1.37. The third wet spring with few spawners, 1986, came in at 4.14. Female spawning biomass in those years was about 33 million pounds, a fraction of what it would reach in the 1990s.

Zero of three in wet springs. Zero of seven overall. Small spawning stocks never got there, not even with near-perfect water. Big spawning stocks showed up in wet springs six out of seven times, and dry water didn’t shut them out completely. In fact, they had a 25% success rate, including the 2^nd biggest spawn ever recorded during a major drought in 2001.

This points one way: two good year classes from big stocks in dry springs, none from small stocks in the best springs. The way we see it, the environment does matter. However, the number of fertile females in the water matters far more.

What the numbers say together

We also ran a standard statistical test: a regression of the Maryland index on spawning biomass, spring river flow and spring temperature, using all 42 years from 1982 to 2023. In our analysis, after accounting for flow and temperature, doubling the spawning stock goes with about a 70 percent higher typical juvenile index (the geometric-mean version of Maryland’s index). That effect is statistically strong: if spawners had no effect, a result this strong would turn up by chance less than one time in a thousand. Flow and temperature matter too. Each degree Fahrenheit warmer from February to May goes with about a 21 percent lower typical index. Together, these three things explain a little more than half of the year-to-year swings in the index.

Some will say the link fades if you set the 1980s aside. That’s the point. From 1982 through 1988 spawners were lower than at any other time in the assessment record, and recruitment fell short of average in every one of those seven years. We think that is what a stock-recruitment relationship looks like in real data: noisy, pushed around by the weather, and still there.

The 1982 year class

The 1982 Maryland index was 8.45, an ordinary number. After a decade of failures, it was cause for celebration. Managers did something about it. Maryland closed its striped bass fishery on January 1, 1985. ASMFC’s Amendment 3 raised size limits so that at least 95 percent of the 1982 females could spawn at least once.

It worked. Female spawning biomass went from 39 million pounds in 1987 to 53 million in 1988 and 81 million in 1989. When scientists from the University of Maryland surveyed eggs on the spawning grounds in 1989, the 1982 year class laid 54.7 percent of the eggs in the upper Chesapeake Bay and 41.8 percent in the Potomac. One average year class, protected until it could reproduce, became a backbone of the recovery.

1989: a bad start and a huge year class

1989 was not an easy spring. March and April river flows were below average. In early May a cold snap dropped water temperatures to about 12 degrees Celsius, the level that kills striped bass eggs and newly hatched larvae. On the Potomac, the researchers on the water reported that the cold “apparently killed most larvae from the earlier hatches.” In the upper Bay, the cold delayed spawning and was believed responsible for significant losses of early eggs and larvae. The upper Bay fish that made the year class came mostly from a late-May spawn, helped by high May river flows. Our spring ranking, which uses monthly averages, doesn’t capture that cold snap at all.

That spring still produced the best Maryland juvenile index in nearly two decades, the highest since 1970. The researchers pointed to the egg counts. In the upper Bay, the female spawning biomass estimated from egg production went from about 19,200 pounds in 1988 to about 156,100 pounds in 1989. That is roughly eight times the spawning biomass in a single year.

The scientists who did the work, Houde and Rutherford of the University of Maryland’s Chesapeake Biological Laboratory, wrote the conclusion themselves: “The probable importance of spawning stock biomass to recruitment must not be underestimated. In the Upper Bay, when the temperature regimes experienced by surviving 1988 and 1989 cohorts were similar, the higher recruitment in 1989 resulted from a much higher egg production.”

Same kind of water, more spawners, more fish.