Rates of sexual maturation of Atlantic cod in NAFO Division 5Ze and commercial fishery implications
An analysis of maturity data for Georges Bank cod (Gadus morhua) in NAFO Division 5Ze, derived from Canadian 1986–94 spring research surveys, showed a significant de-crease in the total length (~4 cm) and age (~0.5 years) of fish at fifty percent maturity, over the nine year period. Differences in m...
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| Format: | Text |
| Language: | English |
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1996
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.518.5910 http://journal.nafo.int/J18/hunt.pdf |
| Summary: | An analysis of maturity data for Georges Bank cod (Gadus morhua) in NAFO Division 5Ze, derived from Canadian 1986–94 spring research surveys, showed a significant de-crease in the total length (~4 cm) and age (~0.5 years) of fish at fifty percent maturity, over the nine year period. Differences in mean size-at-age for males and females appeared to occur after the age at which full maturity was achieved, allowing the use of data pooled by sex for estimating maturity ogives by length and age. Maturity ogives, derived from the pre-fishery survey data, were adjusted for growth and used to estimate commercial landings of immature cod. Results indicated that over 40 % by number and 20 % by weight of the 1987 catch was of juvenile cod from the 1985 year-class. However, the average 1987–93 catch of juveniles was substantially lower at 15 % by number and 6 % by weight with a decrease in the latter part of the time series. Estimates based on maturity-at-length and at age gave similar results but length was considered the better estimator. |
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