Abstract
Crab pots were used to sample a population of Scylla serrata (Forskal) in an estuarine area in Queensland, Australia. Pots were laid 100 m apart at fixed positions for 4 d each month for 1 yr (April 1980–June 1981). Data from recapture of tagged crabs showed that males larger than 140 mm carapace width and females larger than 150 mm had a higher capture probability than did smaller crabs; thus size-frequency distributions based on crab-pot captures are biased. Spacing trials showed that pots positioned 50 m apart fished competitively but that there was no difference in catch between those placed 100 and 200 m apart. Catch distribution indicated that the presence of a crab in a pot reduced the probability of further captures. Temperature and incidence of recently moulted crabs accounted for 66% of variation in monthly catches. Catch-per-unit-effort (CPUE) data can be used as a measure of relative abundance of adults if allowance is made for temperature and the incidence of moulting. The capture-mark-release-recapture method for making population estimates was tested but it is concluded that, because of cost and bias in collecting techniques, it cannot be recommended as a technique for studying S. serrata.
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Communicated by G. F. Humphrey, Sydney
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Williams, M.J., Hill, B.J. Factors influencing pot catches and population estimates of the portunid crab Scylla serrata . Mar. Biol. 71, 187–192 (1982). https://doi.org/10.1007/BF00394628
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DOI: https://doi.org/10.1007/BF00394628