on Georges Bank
George Liles, NOAA
NMFS Northeast Fisheries Science Center
N E W S
Haddock Baby Boom Detected on Georges Bank
Woods Hole, Mass. -- Resource surveys conducted by federal fishery scientists in late summer and fall of 2003 have detected evidence suggesting that spawning haddock on Georges Bank have produced the largest incoming group of young fish in forty years, and perhaps the largest on record for the stock.
How many are there? “A lot,” says Dr. Russell Brown, who is in charge of the Center’s resource surveys. “Right now, we’re measuring by the number of baby fish caught per tow in the trawl survey net, which uses a liner to capture small fish and other sea life. We got an average of about 154 young haddock per tow this autumn. That’s the highest ever recorded in the survey, nearly twice as much as the previous record, and about 30 times the average since 1963,” said Brown.
Subsequent, similar surveys conducted by researchers in the United States and Canada will further refine estimates of the 2003 year-class size as individuals age and grow large enough to reproduce, and to be harvested. The old catch-per-tow record for “age-zero” fish (those younger than one year) was about 84 fish per tow in 1963, which eventually became the largest group of one-year-old haddock ever observed -- 486 million fish.
“This is quite promising, but we’re not home free,” said Dr. Steven Murawski, who leads the Center’s effort to track changes in fish populations. “These young fish have to survive their first few years. It’s critical to keep harvests at or below the target rate -- taking about one in five mature fish every year -- and to keep discard at a minimum.” If that happens, researchers believe Georges Bank haddock could be fully rebuilt to 250,000 mt, a level that many thought was unattainable, before the end of the decade.
Research also indicates that the haddock stock may have passed an important biological milestone. “Historically, when haddock spawning biomass is above 75 thousand metric tons, the odds of an above-average year-class are 30 times greater than when spawning biomass is below that level,” said Dr. Jon Brodziak, who studies haddock, and the relationship between spawning stock size and production of age-zero fish. “There are about 120,000 metric tons of spawners out there now, the most since 1967, and about ten times what was there in 1993, before groundfish rebuilding began in earnest,” he said.
The stock may also be benefitting from optimum conditions for good survival of eggs and larvae. Studying what environmental conditions are favorable to groundfish reproduction on Georges has been a focus for Center oceanographer, Dr. David Mountain. “Wind-driven currents during the spring of 2003 appear to have been quite different from other years, and may have resulted in increased retention of eggs on Georges Bank,” Mountain suggested. “If this hypothesis is correct, these environmental conditions may have contributed to a high survival rate from spawning to the early juvenile for the 2003 year class.”
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