Survival of a herring stock subjected to a catastrophic event and fluctuating environmental conditions

• Published in: ICES Journal of Marine Science
• Main Authors: Winters, G. H., Wheeler, J. P., Dalley, E. L.
• Format: Text
• Language: English
• Published: Oxford University Press 1986
• Subjects: Articles; Newfoundland
• Online Access: http://icesjms.oxfordjournals.org/cgi/content/short/43/1/26; https://doi.org/10.1093/icesjms/43.1.26

The population dynamics of a northerly located stock of predominantly springspawning herring in St. Mary's—Placentia Bay, Newfoundland, were examined as a test of the hypothesis that variations in growth and recruitment are largely a function of fluctuating environmental stress. Adult growth is shown to be primarily temperature- dependent whereas variations in juvenile growth are mainly density-dependent. Correlation analyses point toa cross-over in spawning season between spring-and fall-spawning herring, and this interchange is attributed to annual variations in juvenile growth rates. Despite a substantial decline in abundance as a result of a catastrophic mortality caused by industrial pollution, poor recruitment, and fishery removals, parent stock size (and hence total egg production) was not a significant factor in determining recruitment variability. Rather, recruitment variability is largely caused by fluctuations in overwintering (i.e. prespawning) temperature and salinity. We postulate that the mechanism responsible for such recruitment resiliency is density-dependent changes in hatching success and conclude that it is this feature of the reproductive biology of St. Mary's–Placentia Bay herring which must account for its survival and resurgence after a period of substantial population decline.