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Stepwise function of natural growth for S cylla serrata in E ast A frica: a valuable tool for assessing growth of mud crabs in aquaculture
Author(s) -
Moksnes PerOlav,
Mirera David Oersted,
Björkvik Emma,
Hamad Muumin Iddi,
Mahudi Humphrey Matalu,
Nyqvist Daniel,
Jiddawi Narriman,
Troell Max
Publication year - 2015
Publication title -
aquaculture research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.646
H-Index - 89
eISSN - 1365-2109
pISSN - 1355-557X
DOI - 10.1111/are.12449
Subject(s) - scylla serrata , biology , carapace , aquaculture , growth function , fishery , ecology , juvenile , metamorphosis , crustacean , larva , fish <actinopterygii> , statistics , mathematics
Predicting growth is critical in aquaculture, but models of growth are largely missing for mud crab species. Here, we present the first model of natural growth in juvenile and adult mud crabs S cylla serrata from E ast A frica using a stepwise growth function based on data on intermoult periods and growth at moult from field mark‐recapture, pond and laboratory studies. The results showed a sigmoid growth pattern in carapace width and suggest that S . serrata in E ast A frica will reach 300 g and sexual maturity ~9.9 months after settlement, and a commercial size of 500 g after 12.4 months. Analyses of the literature identified several issues with the common praxis to compare standard growth measures between aquaculture studies with different initial size or growing periods. Using the new growth function to estimate the proportional difference between modelled and obtained growth as an alternative method, we show that growth rates of S . serrata cultured in cage systems, which are dominant in E ast A frica, was <40% of the estimated natural growth and growth obtained in pond systems. The analysis also indicated that growth rates of S . serrata in S outheast A sia was over 50% higher compared with similar culture systems in E ast A frica, and that different species of mud crabs had large differences in growth rates. This study shows that growth in the present mud crab aquaculture systems in E ast A frica is below their expected potential. Further work is needed to identify the factors behind this observation.