Publisher :
Place of publication :
Publication year : 2009
Thematic : Fisheries
Language : English
Note
To evaluate how fishing practices affect bycatch survival and to identify opportunities to reduce bycatch
mortality, we estimated the odds of hooking survival for common bycatch species in the Canadian longline
fishery for swordfish (Xiphias gladius) and tunas (Thunnus spp.) fishing in the North Atlantic. Generalized
linear models, with binomial response, were based on 859 sets observed between 2001 and 2004
and were tested using data from 2005 and 2006. Bycatch included targeted species in poor condition
or below regulatory size limits. Odds of survival were two to five times higher for swordfish, yellowfin
tuna (Thunnus albacares), pelagic stingray (Pteroplatytrygon violacea), porbeagle (Lamna nasus) and blue
shark (Prionace glauca) caught on circle hooks compared to J-hooks during the 2001–2004 period. Further,
odds of severe hooking injuries decreased for three shark species caught on circle hooks. We found no
conservation benefit for loggerhead turtles (Caretta caretta) from circle hook use. Increased circle hook
use coincided with increased targeting and higher landings of tunas. Hooking survival rates and, therefore
opportunities to reduce bycatch mortalities differed among the 10 species commonly discarded or
released. Where the odds of survival to the time of release are high (e.g., loggerhead turtles, pelagic stingray,
blue shark), methods to reduce post-release mortality can be considered. Where the odds of hooking
survival are low (e.g., swordfish and longnose lancetfish, Alepisaurus ferox), methods to reduce encounter
rates would have greater conservation impact.
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Keywords : Prosciurillus rosenbergii
Encoded by : Pauline Carmel Joy Eje
