Generalised linear modelling of fecundity at length in southern rock lobsters, Jasus edwardsii
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Accurate fecundity estimates are central to population modelling of reproductive status and egg production in a fishery. Southern rock lobster (Jasus edwardsii) fisheries are managed with the consideration of performance measures based on the level of current egg production relative to the unfished stock. Egg production is a function of the size at the onset of maturity, the size structure of the stock, and the fecundity at length of lobsters. Fecundity at length of the Tasmania stock of J. edwardsii has not been reported previously and was estimated from seven sites around Tasmania. Data were analysed by classical linear regression and also generalised linear models (GLM) with gamma and Poisson distributions. GLM with a gamma distribution produced the best fit and did not require a correction factor to generate a model on the linear scale. Individual fecundity ranged from 43,918 to 660,156 and could be predicted from carapace length according to the equation F = −1.707 + 2.969 (log length). The coefficient of length approximated three, implying the fecundity at length relationship is cuboidal. Despite the spatial heterogeneity in reproductive parameters in this fishery, the inclusion of spatial information and egg development stage into the analysis only explained an additional 1% of the variance in fecundity. Thus, it appears valid to apply the relationship across the fishery without spatial separation.
KeywordsGeneralise Linear Model Gamma Distribution Carapace Length Length Relationship Rock Lobster
We thank D. Tarbath, R. Pearn, P. Terry, G. Zucherans, M. Edmunds and C. Sanderson for field and laboratory assistance. Thanks also to G. McPherson for invaluable advice for data analyses.
- DeMartini EE, DiNardo GT, Williams HA (2003) Temporal changes in population density, fecundity, and egg size of the Hawaiian spiny lobster (Panulirus marginatus) at Necker Bank, Northwestern Hawaiian Islands. Fish Bull (Wash DC) 101:22–31Google Scholar
- Goni R, Quetglas A, Renones O (2003) Size at maturity, fecundity and reproductive potential of a protected population of the spiny lobster Palinurus elephas (Fabricius, 1787) from the western Mediterranean. Mar Biol (Berl) 143:583–592. doi: https://doi.org/10.1007/s00227-003-1097-5 CrossRefGoogle Scholar
- Junio MAR (1987) Some aspects of the reproduction of Panulirus penicillatus. Bull Mar Sci 41:242–252Google Scholar
- Silberbauer BI (1970) The biology of the South African rock lobster Jasus lalandii (H. Milne Edwards) 1. Development. Division of Sea Fisheries, 92, Cape TownGoogle Scholar