Their study suggests that the condition of the adult haddock not only leads to an improved chance to reproduce, but that the adults will produce more eggs of higher quality with higher fertilization rates. Those factors in turn will produce more abundant, larger and potentially better-conditioned offspring with a higher probability of survival to adulthood, which can significantly affect haddock stocks.
Georges Bank haddock have been heavily fished by domestic and foreign fleets over the past 50 years, with shifting patterns of fishery yields that are largely dependent on successful recruitment events. The paradigm that processes affecting mortality during the early life stages determine recruitment has guided research on Georges Bank for decades, with many recent studies suggesting that the formation of each incoming year class of new fish is driven by differing sets of external environmental factors ranging from climate change patterns like the North Atlantic Oscillation to timing of spawning and the feeding environment.
Friedland and colleagues suggest a new paradigm, that the condition of parents affects egg size and fertilization success through the most difficult growth-mortality period early in the haddock life cycle. The bottom line: the number and quality of offspring is more important than the external environmental factors that occur after spawning.
We need to be able to explain extreme recruitment events for species like haddock, where recruitment is typified by highly unusual circumstances like that in 2003, Friedland says. Factors that may be responsible for these large recruitments will help dictate how the haddock resource on Georges Bank is utilized and conserved. This new hypothesis needs to be tested, but it seems to be the only one that explains the 2003 record year class. If it proves true, the implications could be significant.
|Contact: Shelley Dawicki|
NOAA National Marine Fisheries Service