Effect of the salt-box catch-bycatch separation procedure, as used by the Texas shrimp industry, on short-term survival of bycatch
Colura, R.L.; Bumguardner, B.W. (2001). Effect of the salt-box catch-bycatch separation procedure, as used by the Texas shrimp industry, on short-term survival of bycatch. Fish. Bull. 99(3): 399-409
In: Fishery Bulletin. US Government Printing Office: Washington, D.C.. ISSN 0090-0656; e-ISSN 1937-4518, more
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| Authors | | Top |
- Colura, R.L.
- Bumguardner, B.W.
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| Abstract |
Experiments were conducted to determine the effect of the salt-box catch-bycatch separation procedure, as used by the Texas shrimp industry, on short-term survival of bycatch. Bioassays were conducted on five economically important bycatch species: spotted seatrout (Cynoscion nebulosus); red drum (Sciaenops ocellatus); Atlantic croaker (Micropogonias undulatus); southern flounder (Paralichthyes lethostigma); and blue crab (Callinectes sapidus). Red drum were most affected by hypersalinity, requiring 17 minutes exposure to a 70 parts per thousand salt water solution to kill 50% of the test specimens within 48 hours. For samples collected from commercial boats and Texas Parks and Wildlife (TPW) trawl samples, we found that neither initial nor final percent survival was significantly different for bycatch removed with or without the aid of a salt-box, Bycatch mortality was high regardless of the method used to separate bycatch from the target catch, At the conclusion of catch separation, bycatch survival averaged 76% (+/- 22%) for commercial samples and 48% (+/- 40%) for TPW trawl samples separated with salt-boxes. Survival at the conclusion of catch separation without a salt-box averaged 56% (+/- 35%) for commercial samples and 43% (+/- 39%) for TPW trawl samples. Bycatch survival 21-27 h after catch separation averaged 13% (+/-6%) for commercial samples and 5% (+/-9%) for TPW trawl samples separated with salt-boxes and 34% (+/- 29%) for commercial samples and 10% (+/- 19%) in TPW trawl samples separated without a salt-box. Mortality rates (AT) for bycatch separated with a salt-box averaged 0.08 (+/-0.03) for commercial samples and 0.10 (+/-0.04) for TPW trawl samples. For bycatch separated without the salt-box, M averaged 0.48 (+/-1.23) for commercial samples and 0.10 (+/-0.05) for TPW trawl samples. Results of an exploratory analysis with stepwise multiple regression suggested that final percent survival of bycatch was most affected by trawling time. The salt-box had little or no effect on bycatch survival; therefore, regulating the use of salt-boxes in shrimp trawling operations is not necessary. |
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