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Parametric relationships of recruitment to an index of parental stock size assume the latter is proportionally related to spawning potential, irrespective of the demographic composition of adults. Recent empirical information, however, suggests that repro-duction by older and experienced females is...
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| Format: | Text |
| Language: | English |
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.605.8460 http://icesjms.oxfordjournals.org/content/58/5/1002.full.pdf |
| Summary: | Parametric relationships of recruitment to an index of parental stock size assume the latter is proportionally related to spawning potential, irrespective of the demographic composition of adults. Recent empirical information, however, suggests that repro-duction by older and experienced females is more successful than by young and inexperienced females. New models are developed incorporating the proportion of each age group spawning for the first, second, etc., time (from information contained in the maturity ogive) and differences in the survival of eggs and larvae in relation to the demography of spawners (based on experimental results). A series of spawning metrics [spawning-stock biomass (SSB), egg production, hatched egg production, viable larval production] and associated recruitment-based fishing mortality reference points (Fmed, Fcrash, and the F that allows at least one lifetime spawning per recruit) are contrasted for the Georges Bank Atlantic cod (Gadus morhua) stock. The time-series of spawning intensity is significantly altered when hatched eggs or viable larvae are used as the metric, reflecting the contribution of first- and second-time spawners in some years, and the increasing trend in F. The effect of reduced average maternal size in |
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