Cetorhinus maximus and their Implications for Management of Whale Sharks Rhincodon typus
New methods were used to reanalyse previously published length-frequency data on basking shark Cetorhinus maximus and thereby resolve an earlier controversy about the growth rate ofthis fish. These methods confirm earlier suggestions of a slow growth (von Bertalanffy K>0.06/year, for an asymptoti...
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| Format: | Text |
| Language: | English |
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.310.2128 http://www.seaaroundus.org/researcher/dpauly/PDF/2002/Books%26Chapters/GrowthMortalityBaskingSharkImplicationsWhaleShark.pdf |
| Summary: | New methods were used to reanalyse previously published length-frequency data on basking shark Cetorhinus maximus and thereby resolve an earlier controversy about the growth rate ofthis fish. These methods confirm earlier suggestions of a slow growth (von Bertalanffy K>0.06/year, for an asymptotic length of 10m), and correspondingly low natural mortality (M>0.07/year), as appropriate for a fish with a record length of 9.7m. Given what is known of the inverse relationship between asymptotic length and K in hundreds of fish species (including sharks), the above results imply that whale sharks Rhincodon typus should exhibit, for an asymptotic length of 14m, K and M values of about 0.03 and O.OS/year, respectively. Such slow growth and the high longevity this implies should make whale sharks even more sensitive than basking sharks to human-induced mortality, thus arguing against exploitation by fisheries. Also, ecotourism schemes will have to be careful to avoid becoming a source of indirect mortality. |
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