Risk factors for seabird bycatch in a pelagic longline tuna fishery

Gilman, Eric, Chaloupka, Milani, Peschon, John and Ellgen, Sarah (2016) Risk factors for seabird bycatch in a pelagic longline tuna fishery. PLoS ONE, 11 5: . doi:10.1371/journal.pone.0155477


Author Gilman, Eric
Chaloupka, Milani
Peschon, John
Ellgen, Sarah
Title Risk factors for seabird bycatch in a pelagic longline tuna fishery
Journal name PLoS ONE   Check publisher's open access policy
ISSN 1932-6203
Publication date 2016-05-18
Year available 2016
Sub-type Article (original research)
DOI 10.1371/journal.pone.0155477
Open Access Status DOI
Volume 11
Issue 5
Total pages 24
Place of publication San Francisco, CA, United States
Publisher Public Library of Science
Language eng
Formatted abstract
Capture in global pelagic longline fisheries threatens the viability of some seabird populations. The Hawaii longline tuna fishery annually catches hundreds of seabirds, primarily Laysan (Phoebastria immutabilis) and black-footed (P. nigripes) albatrosses. Since seabird regulations were introduced in 2001, the seabird catch rate has declined 74%. However, over the past decade, seabird catch levels significantly increased due to significant increasing trends in both effort and nominal seabird catch rates. We modelled observer data using a spatio-temporal generalized additive mixed model with zero-inflated Poisson likelihood to determine the significance of the effect of various risk factors on the seabird catch rate. The seabird catch rate significantly increased as annual mean multivariate ENSO index values increased, suggesting that decreasing ocean productivity observed in recent years in the central north Pacific may have contributed to the increasing trend in nominal seabird catch rate. A significant increasing trend in number of albatrosses attending vessels, possibly linked to declining regional ocean productivity and increasing absolute abundance of black-footed albatrosses, may also have contributed to the increasing nominal seabird catch rate. Largest opportunities for reductions are through augmented efficacy of seabird bycatch mitigation north of 23° N where mitigation methods are required and during setting instead of during hauling. Both side vs. stern setting, and blue-dyed vs. untreated bait significantly reduced the seabird catch rate. Of two options for meeting regulatory requirements, side setting had a significantly lower seabird catch rate than blue-dyed bait. There was significant spatio-temporal and seasonal variation in the risk of seabird capture with highest catch rates in April and May and to the northwest of the main Hawaiian Islands.
Keyword Seabirds
Laysan (Phoebastria immutabilis) albatrosses
Black-footed (P. nigripes) albatrosses
Seabird bycatch mitigation
Fisheries
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: HERDC Pre-Audit
School of Biological Sciences Publications
 
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