Research on live-bearing fishes of the genus Sebastes has shown positive relations hips between the age of females and the quality of their offspring, where “quality” is measured as size, oil globule volume, growth rate, days to starvation, and/or swimming speed. Females of different age classes may also spawn at different times, with younger females generally releasing their larvae later in the parturition season. These studies have reintroduced an important concept in life history evolution that ties to fisheries management: the potential need to preserve age structure of the spawning stock, not simply biomass. We are investigating the age-specific characteristics of spawning Pacific Ocean perch (POP) Sebastes alutus from the Gulf of Alaska to see if the patterns observed in nearshore rockfishes also occur in this deep water species. In general, we have found support for age-related differences in reproductive characteristics among females although these signals do not appear as strong as that seen for shallow-water species. Our attempt to approximate the timing of parturition for females collected through trawl sampling may have been confounded by an interesting phenomenon – approximately 3% of females examined show evidence of differential development between the two ovarian lobes, suggesting that some fish may release their larvae one ovary at a time. Our research has not found a strong relationship between mother’s age and offspring quality in POP, but has revealed differential timing of release that correlates with age, as well as other important aspects of reproductive physiology in this species. Modeling results indicate that maternal effects are not as important as other impacts to population demographics.

Selina Heppell et al.
Short Description: 
A final report filed with the North Pacific Research Board on preserving age structure of Pacific Rockfish.
Product Number: 
Entry Date: 
Friday, May 9, 2014
52 pp.
Size and Format: 
8 1/2 x 11, online
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Download the report from the North Pacific Research Board.