MORPHOLOGICAL DIFFERENCES BETWEEN WILD AND CULTURED EUROPEAN LOBSTER, MALES AND FEMALES. IMPACT ON SIZE AT MATURITY?
A release program with the objective of enhancing the local stock of European lobster (Homarus gammarus) began off southwestern Norway in 1990 (Agnalt et al. 1999, 2004). A total of 128 000 hatchery-produced lobster juveniles were released over 6 years. The commercial landings were monitored for cul...
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| Format: | Text |
| Language: | English |
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.556.5563 http://www.searanching.org/program/documents/Agnaltetalb.pdf |
| Summary: | A release program with the objective of enhancing the local stock of European lobster (Homarus gammarus) began off southwestern Norway in 1990 (Agnalt et al. 1999, 2004). A total of 128 000 hatchery-produced lobster juveniles were released over 6 years. The commercial landings were monitored for cultured survivors until 2001, 11 years after the first release. From a conservation point of view, one important measure in a release program is to obtain survival to reproductive size or age (e.g. Brown & Day 2002 and references therein). Recaptures of adult lobster, including berried females, have been significant leading to the conclusion that released hatchery-produced juveniles survive and contribute to the total reproduction in the release area (Agnalt et al. 2004). However, the questions remains whether cultured lobster behave or differ from wild ones. It has previously been documented that the physical environment in the hatchery can significantly influence the normal development of the claws of the lobster juveniles (Govind & Kent 1982, Wickins 1986, Korsøen 1994), and improvements in providing a substrate to the produced juveniles have been suggested and implemented. Despite the improvement about 20 to 30 % of the lobsters released had two scissors claws rather than the normal set of one crusher and one scissor. Van der Meeren & Uksnøy (2000) compared claw morphology in wild to those cultured males that had survived with two scissor claws. The largest claw in cultured males was in general longer and thinner than wild male claws. This paper examines morphological differences between wild and cultured lobsters, with emphasis on characteristics often termed as secondary sexual characters such as abdominal width in females and claw size in males. Size at maturity is presented for both sexes. Cultured females are generally narrower in the second abdominal segment than wild females (Figure 1). This is also the case in males. What are the A bd om dt h/ c e le |
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