Reducing seabird bycatch in the Hawaii longline tuna fishery

Gilman, Eric, Kobayashi, Donald and Chaloupka, Milani (2008) Reducing seabird bycatch in the Hawaii longline tuna fishery. Endangered Species Research, 5 2-3: 309-323. doi:10.3354/esr00133

Author Gilman, Eric
Kobayashi, Donald
Chaloupka, Milani
Title Reducing seabird bycatch in the Hawaii longline tuna fishery
Journal name Endangered Species Research   Check publisher's open access policy
ISSN 1863-5407
Publication date 2008-12-01
Sub-type Article (original research)
DOI 10.3354/esr00133
Open Access Status DOI
Volume 5
Issue 2-3
Start page 309
End page 323
Total pages 15
Place of publication Oldendorf, Germany
Publisher Inter-Research
Language eng
Abstract Mortality in longline fisheries represents a global threat to some species of pelagic seabirds. Regulations were adopted in 2001 to reduce seabird bycatch in the Hawaii longline tuna fishery. We used a Poisson generalized additive regression modeling approach to evaluate the change in seabird bycatch rates from the pre- to post-regulation period, and to evaluate the efficacy of alternative combinations of seabird bycatch reduction methods employed during the post-regulation period. Informative covariates of temporal and geo-referenced spatial effects of fishing effort and sampling variation commonly found with count data were included in the model to provide a better inference of the effect of employing required changes in fishing gear and methods. We found a significant 67 % (95 % CI: 62 to 72) reduction in the seabird bycatch rate following the introduction of regulations. Post-regulation, sets employing 4 different combinations of seabird avoidance methods all resulted in significant reductions to the pre-regulation seabird catch rate. Employing side-setting and 60 g weights Was the only combination with no seabird captures during the post-regulation period. Using heavier branch line weights and treated bait (thawed and dyed blue) both significantly reduced seabird catch rates. Temporal and spatial distribution of fishing effort and the timing of initiating setting were also significant factors affecting seabird bycatch rates: time-area closures and restricting the timing of setting could further reduce seabird bycatch. A substantial proportion of seabird captures occurred south of the area where mitigation measures are required: moving the southern boundary farther south would further reduce seabird catches.
Keyword Albatross
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collection: School of Biological Sciences Publications
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