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The biology of the bigeye grenadier at South Georgia

Morley, S.A.; Mulvey, T.; Dickson, J.; Belchier, M.. 2004 The biology of the bigeye grenadier at South Georgia. Journal of Fish Biology, 64 (6). 1514-1529.

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Abstract/Summary

The biology of the bigeye grenadier Macrourus holotrachys caught as by-catch in the Patagonian toothfish Dissostichus eleginoides longline fishery conducted around South Georgia was investigated to improve data available for fisheries management. Age estimates suggest that M. holotrachys is a moderately slow growing species (K = 0.10), reaching ages of >30 years and attaining total lengths (L-T) >80 cm (L-infinity = 33). The size at which 50% of females had started to mature (L-int50) for M. holotrachys was 21 cm pre-anal length (L-PA) and occurred at c. 9 years old. Estimates of natural mortality and Pauly's growth performance index were found to be low (M = 0(.)09 and Phi = 2.82 respectively). Gonad maturity stage was described from macroscopic and histological investigation. Mature ovaries had oocytes at all developmental stages with between 22 and 55% likely to be spawned each year. Absolute fecundity ranged from 22 000 to 260 000 eggs and was positively correlated with both pre-anal length and mass. A highly skewed sex ratio of 32 : 1, females: males, was found for specimens caught by longlines but not for a small sample of shallower trawl-caught specimens. It is suggested that females are far more susceptible to longline capture than males. Macrourus holotrachys is a bentho-pelagic predator and scavenger that feeds on a wide range of fishes and invertebrates. The fish are long lived, slow-growing species typical of deep-water grenadiers; fisheries management strategies should reflect their probable susceptibility to overfishing. (C) 2004 The Fisheries Society of the British Isles.

Item Type: Publication - Article
Programmes: BAS Programmes > Other
ISSN: 0022-1112
Additional Keywords: Fish
NORA Subject Terms: Biology and Microbiology
Date made live: 03 Aug 2010 14:03
URI: http://nora.nerc.ac.uk/id/eprint/10215

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