A scientific estimate of the number of young striped bass in Maryland’s portion of the Chesapeake Bay earlier this year was the lowest on record. But the drop -– following a near-record high last year -– was likely caused by poor weather conditions this spring, and is not a sign of worsening pollution or a crisis in the population of the popular game fish, according to the Maryland Department of Natural Resources.
“Generally, warm winters and dry springs are unfavorable conditions for fish that return to freshwater to spawn,” said DNR Striped Bass Survey Project Leader Eric Durell in a written statement.
Striped bass, which spawn in the Bay’s rivers, often experience erratic spikes and drops in their populations as spring temperatures and the amount of rainfall determine how many of the fertilized eggs hatch and how many of the young survive. Low rainfall in the spring means that Bay tributaries have saltier water, which can kill the larvae of striped bass.
“While we expect large variation in striped bass reproduction from year to year and do not view this low value as an imminent problem, we will be carefully monitoring the results of future surveys,” said DNR Fisheries Director Tom O’Connell. “Three consecutive years of poor reproduction would be necessary to trigger mandatory conservation measures.”
This year’s striped bass juvenile index came in at 0.9, the lowest on record, and a figure significantly lower than the long-term average of 12, according to DNR. The number represents the average number of young striped bass caught by per sample by researchers using a-100-foot seine net along a beach. Last year’s survey, by contrast, showed the fourth highest result (an index of about 35) in the 59-year history of the survey.
The Virginia Institue of Marine Science (VIMS) reached similar conclusions about the drop in young striped bass in 2012, according to a statement issued by the institute. Professor Mary Fabrizio, who directs the VIMS survey, said: “Poor recruitment during 2012 is consistent with patterns observed by our long-term monitoring program. Since the fishing moratorium for striped bass was lifted in 1990, single years of low recruitment have occurred approximately every 10 years, with the last one occurring in 2002."
Historically, highly successful spawning years, such as 1989, 1996, and 2001, were followed by below-average years.
Because of overfishing, striped bass populations crashed during the 1970s and early 1980s –- before rebounding strongly because of moratoriums and catch limits imposed by Maryland, Virginia and other regional states in the late 1980s.
Striped bass eat smaller fish, including menhaden, which have been overfished in the Chesapeake Bay. Scientists are examining whether this overfishing of menhaden is hurting the nutrition and health of striped bass.
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By Tom Pelton
Chesapeake Bay Foundation
(Chart at top from Maryland Department of Natural Resources. Photo of striped bass from NOAA.)