Effects of condition on fecundity and total egg production of eastern Scotian Shelf haddock (Melanogrammus aeglefinus)

• Published in: Canadian journal of fisheries and aquatic sciences Vol. 60; no. 3; pp. 321 - 332
• Main Authors: Blanchard, Julia L, Frank, Kenneth T, Simon, James E
• Format: Journal Article
• Language: English
• Published: Ottawa, Canada NRC Research Press 01.03.2003; National Research Council of Canada; Canadian Science Publishing NRC Research Press
• Subjects: Animal populations; Animal reproduction; Animal, plant and microbial ecology; Applied ecology; Biological and medical sciences; Breeding; Egg production; Energy reserves; Exploitation and management of natural biological resources (hunting, fishing and exploited populations survey, etc.); Fecundity; Fish; Fish stocking; Fundamental and applied biological sciences. Psychology; Haddock; Lipids; Melanogrammus aeglefinus; Spawning; Time series; Canada; Nova Scotia; North America; Northwest Atlantic; America; ANW, Atlantic, Scotian Shelf; Melanogrammus aeglefinus; Egg; Spawning; Coastal zone; Marine environment; Reproduction; Vertebrata; Fishery; Production rate; Pisces; Body size; Population recruitment; Condition index; Fecundity; Reproductive potential; Stock; Hepatosomatic index
• ISSN: 0706-652X; 1205-7533
• DOI: 10.1139/f03-024

A fecundity study of the eastern Scotian Shelf haddock (Melanogrammus aeglefinus) stock during the 1997–1999 spawning seasons is reported. We developed a model that accounted for fecundity changes at the individual level and that could be used to estimate population egg production beyond the study period. Incorporating condition factors into the model (relative condition factor (Kn) and hepatosomatic index) accounted for a significant proportion of the residual variation. The model predicted that a change in Kn from 0.8 to 1.0 resulted in a twofold increase in fecundity at length. This variability was as great as that observed for fecundity–length relationships among stocks. Three time series (1979–2001) of total egg production (TEP) were constructed using different fecundity relationships: one with a condition effect, one based on length only, and one based on weight only. The magnitude of change in TEP resulting from the condition effect ranged from +30 to –20%. Condition effects during the first half of the time series resulted in an enhancement of TEP, whereas in the latter half, condition effects depressed TEP. This evaluation of TEP generated new insights into haddock stock dynamics but did not result in a dramatic improvement of the relationship between recruitment and stock reproductive potential.