During Maryland’s striped bass trophy season this spring, John Mayer could guide his clients to plenty of big striped bass that had migrated from the coast into the Bay to spawn.
“It was the best I’ve ever seen,” said the charter boat captain,who is based in Solomons, MD.
Fishing stayed strong through the early summer, he said, then things got “weird.” Fish became more scarce, and those that were left were getting thinner. “It makes me think they were leaving town — there was not enough to eat,” he said.
“The observation I have is that we have a problem,” Mayer said. “I personally don’t know what the problem is.”
In that, he has a lot of company.
For more than a year, some scientists and fishermen, mostly in Maryland, have been raising concerns about the health of the striped bass. The remarkable rockfish recovery — from a total fishing moratorium a decade ago to record abundance today — is touted as one of the Chesapeake’s biggest success stories.
Yet while there are more striped bass in the Bay today than has been the case for decades, many appear to be thin while others have lesions. All of this is happening at a time when the population of menhaden, the preferred food of striped bass, is unusually low. Such observations have led some to proclaim that rockfish are “starving to death.”
While many think that is an overstatement, concern is everywhere. In November:
- The Maryland Department of Natural Resources convened an internal workshop in which its scientists reviewed the situation. They agreed that the poor condition of striped bass was being observed at a time when populations of “forage” fish were low. But “whether this is coincidence, or cause and effect, is unknown,” they said in a consensus statement.
- The Atlantic States Marine Fisheries Commission — the multijurisdiction agency responsible for managing migratory fish — convened a panel of scientists to review menhaden management. A prime discussion topic: whether management should be adjusted to consider the ecosystem value of menhaden, such as its role as food for predators. A report is expected in December.
- The Bay Program convened a panel of scientists at its Implementation Committee to discuss predator-prey relationships within the Chesapeake. Much of the discussion dealt with the menhaden-striped bass issue.
- Several conservation groups hosted a symposium, “Striped Bass in Crisis?” which drew about 200 people, mostly fishermen, to hear scientists, agency officials and others discuss the situation.
One thing that came out of that discussion was that few people believe there is a “crisis.” But many think something has gone awry.
“I don’t know what’s going on,” said Bob Bachman, director of the Maryland DNR’s Fisheries Service, “but I think I know the difference between a problem and a crisis. We’ve got a problem.”
It’s just that no one knows exactly what the problem is, or what can be done about it.
People generally agree on two key points:
- There are more striped bass in the Bay now than at any time in recent decades. That’s the result of conservative management actions that followed a total fishing moratorium in the late 1980s. Management today seeks to control fishing pressure to ensure that the population does not collapse as it did in the early 1980s. As a result, the total weight of the reproducing striped bass population — the spawning stock biomass — is twice what it was in the 1960s. Reproduction has been higher than average almost every year since 1993, with two of those years being the best on record.
- The numbers of menhaden are the lowest since the 1960s. But the spawning stock biomass is higher than it has been for decades, largely because the population is increasingly made up of larger, older fish. That means there is a potential for a population boom whenever the spawning fish meet the right environmental conditions. But that hasn’t happened in years. Menhaden numbers have declined mainly because the population has had several years in a row of unusually poor reproduction.
The question perplexing scientists is how — and whether — the high striped bass abundance and low menhaden abundance are intertwined. Evidence is not clear, and some studies appear to be contradictory.
In fact, surveys by the Virginia Institute of Marine Science indicate that striped bass in that portion of the Bay are finding menhaden to eat. Menhaden accounted for 88 percent of the striped bass diet in the summer of 1997 and 71 percent that fall, according to figures from the study, which examined about 2,000 striped bass.
“I don’t think the striped bass is in danger,” said VIMS scientist Herb Austin, who oversaw the study.
But in Maryland, two separate surveys, one conducted by the state and one by university researchers, found that about 70 percent of striped bass examined had little or no body fat stored. Little evidence of menhaden was found in their stomachs. Fish in poor condition were found throughout the Bay, in all ages and both sexes.
“If some underlying stressor is at work, like they’re not getting enough to eat as some have suggested, this is probably what we would expect to see,” said Steve Jordan, director of the Oxford Cooperative Laboratory, which is jointly run by the Maryland Department of Natural Resources and the National Marine Fisheries Service.
In Maryland, striped bass stomachs had few menhaden, but more crabs, bay anchovy and other less desirable fish. Jim Price, president of the Chesapeake Bay Acid Rain Foundation, said he has seen menhaden in 6 percent of the 203 Maryland striped bass he examined this year and last, and he said the average weight of an 18-inch rockfish has declined 23 percent since 1992. Menhaden is an oily fish that is considered more nutritious because it helps to build up body fat.
In both states, more lesions were observed than in the past, regardless of whether the fish were thin or fat. In Maryland, about 15 percent had external lesions, and a similar number had internal infections not visible from the outside.
But is that the sign of a problem, or normal biology?
Some note that as a fish population expands, it’s normal for individuals to begin competing for food, resulting in slower growth rates. “These are responses that are often seen in fish populations when abundances are unusually high,” said Ed Houde, a fisheries biologist with the University of Maryland’s Chesapeake Biological Laboratory. “The basic rule is that when things are abundant and competing with each other, ‘density dependent’ factors kick in. Growth goes down, the mortality rate may go up, things like communicable diseases, which I think these skin diseases are, become more prevalent. It’s what you would expect.”
At the same time, Houde and others said the lack of menhaden reproduction is a concern, and one that should be examined.
Menhaden lay their eggs off the coast, usually during the winter. After 50 to 80 days, the larvae move into bays to feed. But survival of menhaden young has been low for the several years, and no one knows why.
It’s possible the series of unusually high flows that have flushed through the Bay and other coastal areas in recent years may have altered water quality for the young fish.
Claire Buchanan, a biologist with the Interstate Commission on the Potomac River Basin, said monitoring data shows the Bay has become more turbid — its waters clouded with dirt — in recent years. That’s coincided with an apparent shift in the populations of phytoplankton toward species that are less desirable for filter feeders such as menhaden, and declines in summer populations of zooplankton.
Others question whether links between water quality, phytoplankton and zooplankton, and menhaden larvae can be solidly made.
Austin noted that while menhaden numbers have been down, so have populations of other ocean-spawning fish, such as spot. Meanwhile, river-spawning fish, such as striped bass and some species of shad, have been doing well. That trend was reversed in the 1980s. Some, Austin said, believe that climatic conditions rarely favor ideal conditions for both ocean-spawning and river-spawning species to occur at the same time.
“It’s important that we not forget that these fluctuations may be perfectly natural.” he said.
What can be done about such fluctuations looms as a big question.
Some say that menhaden and striped bass management plans should be changed so fishing rates reflect, at least in part, the abundance of the other species.
For example, if the commercial menhaden catch in the Bay were lower, it would make more fish available for predators, such as striped bass, weakfish and blue fish, to eat. The Atlantic Coast menhaden catch is about 300 thousand tons a year, more than 60 percent of which comes out of the Chesapeake. The fish are used to produce oil and to make chicken and other animal feeds.
“It might help buy time to get the dominant year class we need,” said Sherman Baynard, chairman of the Maryland Coastal Conservation Association, which sponsored the “Striped Bass in Crisis?” symposium along with the Chesapeake Bay Foundation and the Chesapeake Bay Acid Rain Foundation.
Conversely, if the menhaden population remains low, some believe a case could be made that fishing pressure on striped bass should be increased for the sake of the menhaden.
Such “multispecies management” considerations — in which interrelationships between species or ecosystem services provided by species — are not presently incorporated in any fishery management plans along the East Coast.
Besides serving as an important source of prey for striped bass and other predators, menhaden are — like oysters — important filter feeders that can remove large amounts of bloom-forming algae from the water.
“One thing I think we can say for sure is that the menhaden role ecologically, as well as its role as a commercial fishery, needs to be considered,” said Bill Goldsborough, senior scientist with the Chesapeake Bay Foundation.
That may happen soon. Those relationships were a key issue examined by a panel of scientists who gathered from across the nation to review ASMFC’s menhaden management. Their recommendations are expected to be available for public review in December.
Austin noted that, although his surveys don’t indicate a problem for striped bass, management plans should better reflect the value of forage species. He said that not only should more efforts be placed on menhaden, but also other small forage fish, such as bay anchovy, even though they are not targeted by any fishery.
Many forage fish are short-lived, Austin said, and the health of their stocks may more quickly reflect important environmental or climatic changes than larger, sport or commercial species.
“Whether there is a problem or not, let’s go ahead and get a management plan written which at least identifies what we should be watching for what the potential problems are, so that everyone sees the importance of all these little fish that nobody has ever paid any attention to,” Austin said. “Maybe they would make a good index of the health of the Bay.”
Goldsborough said striped bass management may have resulted in the rockfish’s recovery outpacing the Bay’s recovery.
While the number of striped bass in the Bay has increased dramatically, the quality of their habitat has not. The size of the oxygen-starved “dead zone” has not shrunk in recent years — this year it was among the worst on record. This has the effect of squeezing a growing striped bass population into smaller areas.
Critical habitats, such as grass beds and oyster reefs, which can help support other forage species for striped bass, remain severely depleted. “I think lack of menhaden in the Bay is part of the problem,” Goldsborough said, “but it’s not the whole problem.”
Understanding these predator-prey relationships should be a “high priority” because it would help officials make better management decisions, Houde said. But he cautioned against making quick judgments about the striped bass. The stock, he said, does not appear to be at risk.
“I know of no population of fish in the world that starved to death,” Houde said. “But populations in poor condition can be exposed to factors that might increase their mortality rate or reduce their reproductive rate due to poor condition.”
If the striped bass stock was “nutritionally stressed” because of a lack of food, he said, that would ultimately result in poor reproduction — something that has not been the case. If those signs emerge, Houde said the present population is strong enough to withstand several years of poor reproduction without jeopardizing the stock, as long as it is not overfished at the same time.
“Whether there is enough food to feed striped bass is a good question, and we ought to be looking at that,” Houde said. “On the other hand, I don’t get very worried. This is the greatest striped bass fishery we’ve ever seen. It’s spectacular. The population might decline significantly because they are deprived of food, but I would be very surprised if the population collapsed.”