Population dynamics of the antarctic opisthobranch Philine gibba Strebel

Population structure and growth of Philine gibba Strebel have been examined using weight- and length-frequency analyses. The population consisted of five year classes but the 4th and 5th year classes were only separable immediately after spawning. Sexual maturity was reached after ≈ 3 yr, spawning occurred at 3.75 yr and death, after a second spawning, at 4.75 yr. Somatic growth was discontinuous and reproduction caused a mean somatic weight loss of 30.2% (ash-free dry wt). Shell growth was interrupted briefly during reproduction and the growth rate increased during the first 18 months of life but decreased steadily thereafter. Mortality of juveniles was high and during the 2-yr study there was negligible recruitment to the mature population. High mortality of juveniles was attributed to intraspecific competition for food and size-specific predation.

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