Striped Bass (Rockfish)

Maintaining Our "Restored" Striped Bass Population

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Striped bass are often seen as the greatest success story of the Chesapeake Bay. Populations of this iconic sport fish plummeted in the 1970s and early 1980s, but then rebounded because of tightened catch restrictions in a dozen states from 1985 to 1990, including a moratorium on catching them in Maryland, Virginia and other states.

A New Decline

Today, we face a new decline, albeit one that has not taken "stripers" anywhere near as low as last time. According to the latest science developed by the Atlantic States Marine Fisheries Commission—a regional fisheries management board—the Atlantic striped bass stock (which includes populations from the Bay and Delaware and Hudson Rivers) has been declining since 2004 when it was at an all-time peak. Concurrently, recreational catches have dropped steadily, especially at the edges of the range of the species in New England and North Carolina—shrinking of a fish's range is a sure sign of decline in the population. To protect this important species and reverse the decline, the commission recently voted to consider a reduction in the allowable catch of striped bass by up to 25 percent beginning in 2015.

CBF Senior Fisheries Scientist Bill Goldsborough, who serves on the commission, said that cutbacks would be a wise move. He said the Atlantic states need to move beyond the "wait-for-a-crisis" style of fisheries management that allowed the rockfish crash in the early 1980s and instead adopt a preventative style.

Water Pollution and Poor Diet

Goldsborough explained that water pollution and poor diet may be partly to blame for the recent decline in striped bass. "Their favorite food, menhaden, is at an all-time low, and that appears to be causing problems that we see in the Chesapeake's resident striped bass," Goldsborough said. "They’re skinny, they're diseased, and they're dying at a faster rate, in part because they are not getting enough good nutritious food to eat."

So where is the striped bass' food—these smaller fish, the menhaden—going? Many are being caught by an industrial fishing fleet out of Virginia, which processes them to make livestock and fish feed, fish oil pills, and other products. Virginia is the only state on the coast that still allows this industrial fishing.

Without enough nutrients from menhaden, and stressed by poor water quality, some scientists believe the immune systems of striped bass are becoming suppressed. The theory is that weakened disease-fighting systems make stripers more likely to become ill with a chronic wasting disease called mycobacteriosis, which infects as much as 70 percent of the Bay's striped bass.

The disease is caused by bacteria that are found nearly everywhere in the water and sediment, said Dr. Wolfgang Vogelbein of the Virginia Institute of Marine Science. "We feel that these environmental bacteria…are opportunists, and that disease outbreaks are stress-related," said Dr. Vogelbein, who discovered mycobacteriosis in striped bass in 1997. His lab is now studying the possible link between mycobacteriosis, stress in fish, and low-oxygen "dead zones," often caused by pollution.

Preventing Another Crash

Tom O'Connell, Fisheries Director for the Maryland Department of Natural Resources, noted that the Atlantic states are also considering limits on catching menhaden as a way to prevent another striper population crash.

"The last thing we want to do is get back into a situation where we are faced with a moratorium. Nobody wants to do that," O'Connell said. "Some modest adjustments today would help avoid future significant actions."

In other words, an ounce of prevention is worth a ton of sustainable fishing.

Disappearing at an Alarming Rate

Seventy percent of an adult rockfish's diet historically has been filled by menhaden. Today that's down to eight percent. What is causing the menhaden population to plummet and what can we do about it?

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