Fecundity of haddock (Melanogrammus aeglefinus) off southern Newfoundland

摘要

Reproductive life history parameters, such as size-specific fecundity, can contribute to our understanding of fish population dynamics. However, most of these parameters are difficult or time-consuming to obtain. Therefore, previously calculated parameters are often used in combination with more easily collected metrics of size. Significant temporal variation in fecundity is known to occur in many fish species, meaning that previous estimates may be unreliable when examining contemporary fish stocks. For southern Newfoundland haddock, the only published fecundity data were collected more than 50 years ago when this species supported a major fishery in the area. Here we present fecundity data collected during the 1960s immediately following stock collapse, as well as data from 2013 to 2014 (after 20 years of a fishing moratorium) and examine potential differences in egg production among the time periods. Contemporary estimates of haddock fecundity were more similar to estimates of fecundity immediately following stock collapse than estimates during the period of maximum exploitation. Additionally, comparison of haddock fecundity throughout the northwest Atlantic Ocean revealed contemporary estimates from southern Newfoundland to generally be higher than those from the Scotian Shelf for haddock at all lengths as well as greater than those from George's Bank until about 60 cm in total length. The ability of various fish characteristics (length, weight, age, and condition) to serve as metrics of haddock fecundity were investigated and found that while length was the best predictor of fecundity, explanatory power was relatively low (maximum R-2 = 0.37), and there was little to no effect of fish condition on fecundity. Inter-annual variability in fecundity estimates, coupled with the lack of a suitable proxy for fecundity for Newfoundland haddock suggests that ongoing monitoring is required to accurately estimate reproductive potential.