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Egg production of Baltic cod (Gadus morhua) in relation to variable sex ratio, maturity, and fecundity
Kraus, G.; Tomkiewicz, J.; Köster, F.W. (2002). Egg production of Baltic cod (Gadus morhua) in relation to variable sex ratio, maturity, and fecundity. Can. J. Fish. Aquat. Sci. 59(12): 1908-1920
In: Canadian Journal of Fisheries and Aquatic Sciences = Journal canadien des sciences halieutiques et aquatiques. National Research Council Canada: Ottawa. ISSN 0706-652X, more
Peer reviewed article  

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Keywords
    Egg production; Eggs; Fecundity; Models; Sex ratio; Sexual maturity; Size; Stocks; Time series; Gadus morhua Linnaeus, 1758 [WoRMS]; ANE, Baltic [Marine Regions]; Marine

Authors  Top 
  • Kraus, G., correspondent
  • Tomkiewicz, J.
  • Köster, F.W.

Abstract
    Observed fluctuations in relative fecundity of Eastern Baltic cod (Gadus morhua L.) were related to food availability during the main feeding period and were used to develop a predictive model that explained 72% of the interannual variations in fecundity. Time series of sex ratios, maturity ogives, and relative fecundity were combined with mean weights-at-age and stock sizes from an analytical multispecies model to estimate the potential egg production (PEP). Relationships between PEP and independent estimates of realized daily and seasonal egg production from egg surveys were highly significant. The difference between estimates of potential and realized seasonal egg production was of a magnitude corresponding to the expected loss of eggs as a result of atresia, fertilization failure, and early egg mortality. The removal of interannual variability in sex ratio, maturity, and fecundity on estimates of PEP deteriorated the relationships in all three cases. PEP proved to be superior to spawning stock biomass as measure of the reproductive potential in a stock-recruitment relationship of Eastern Baltic cod. PEP in combination with the reproductive volume explained 61% of the variation in year-class strength at age 2.

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