Age-modulated variation in reproductive development of female Pacific Ocean perch (Sebastes alutus) in waters off Oregon

Age-modulated variation in reproductive development of female Pacific Ocean perch (Sebastes alutus) in waters off Oregon

R.W. Hannah, and S.J. Parker

Age-modulated variation in reproductive development of female Pacific Ocean perch (Sebastes alutus) in waters off OregonThis is part of Biology, Assessment, and Management of North Pacific Rockfishes
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Description

We investigated the maturity of female Pacific ocean perch (Sebastes alutus) in waters off Oregon. Visual and histological methods produced similar results during the months of December to March; however, neither method provided reliable determinations of reproductive maturity in other months. Evidence of abortive maturation, characterized by mass atresia of the developing class of oocytes, was observed in 7.1% of the fish sampled during December to March, with a strong age-related decline in prevalence. Fish older than 18 (N = 73) showed no evidence of abortive maturation regardless of size, further supporting the higher reproductive value of older rockfishes. Abortive maturation was associated with adolescence (age 5-9 years), but was also observed in post-adolescent fish, especially in 2001 samples. Rates of abortive maturation varied between the years 2001 and 2003, suggesting an environmental influence on successful egg development in younger fish. Pacific ocean perch off Oregon were 50% mature at a length of about 31 cm and an age of six, two years younger than assumed in recent stock assessment models for the West Coast population.

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