The fate of discarded juvenile brown shrimps (Crangon crangon) in the Solway Firth UK fishery
In: Fisheries Research. Elsevier: Amsterdam. ISSN 0165-7836; e-ISSN 1872-6763, more
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| Author keywords |
Crangon crangon; Survival; Trawling; Sea bird predation; Management suggestions |
| Authors | | Top |
- Lancaster, J.
- Frid, C.L.J., more
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| Abstract |
The extent of discarding and the survival of juvenile brown shrimps (Crangon crangon) was investigated during a 3 year study of the commercial fishing fleet in the Solway Firth (UK) brown shrimp fishery. Shrimps of 9 mm carapace length and above were considered of marketable size, while those below 9 mm were regarded as undersized. Of all C. crangon captured 52% were below the marketable size. The riddles used to separate the catch rejected 89% of these undersized C. crangon, the remaining 11% were cooked along with the commercial sized shrimps.This study found that 99% of discarded undersized shrimps were returned to the sea alive and after 24 h it was estimated that 92% would have survived. The riddling process did not significantly reduce their survival rate, however, riddling occasionally resulted in the loss of antennae or a telson. Estimates of bird predation on living C. crangon discards ranged from 0.5 to 4.5%. Combining these survival data it was estimated that between 77 and 80% of all undersized C. crangon entering a shrimp beam trawl would survive, depending on the level of bird predation. In view of this high survival level the introduction of a minimum size/count would be an effective management measure to ensure that juvenile C. crangon are not landed if market conditions became favourable for small shrimps. |
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