Southeast Alaska Sperm Whale Avoidance Project (SEASWAP): a successful collaboration among scientists and industry to study depredation in Alaskan waters

TitleSoutheast Alaska Sperm Whale Avoidance Project (SEASWAP): a successful collaboration among scientists and industry to study depredation in Alaskan waters
Publication TypeJournal Article
Year of Publication2015
AuthorsStraley J., O'Connell V., Liddle J., Thode A, Wild L., Behnken L., Falvey D., Lunsford C.
JournalIces Journal of Marine Science
Volume72
Pagination1598-1609
Date Published2015/05
Type of ArticleArticle
ISBN Number1054-3139
Accession NumberWOS:000356233800032
Keywordsanalysis; behavior; behavioural ecology; collaboration; commercial fishing; depredation; fishery; georgia; gulf; Gulf of Alaska; killer whales; longline; orcinus-orca; physeter-macrocephalus; population estimate; sablefish; spatial; sperm whales; tracking
Abstract

In Alaskan waters, depredation on sablefish longline gear by sperm whales increases harvesting cost, negatively biases stock assessments, and presents a risk of entanglement for whales. The Southeast Alaska Sperm Whale Avoidance Project (SEASWAP), a collaborative effort involving industry, scientists, and managers, since 2003 has undertaken research to evaluate depredation with a goal of recommending measures to reduce interactions. Prior to 2003, little was known about sperm whale distribution and behaviour in the Gulf of Alaska (GOA). Although fishers were reporting increasing interactions, the level of depredation varied with no apparent predictor of occurrence across vessels. Between 2003 and 2007, fishers were provided with fishery logbooks and recorded information on whale behaviour, whale presence and absence, during the set, soak, and haul for 319 sets in the GOA. Data were evaluated for a vessel, area, and seasonal (month) effect in the presence and absence of sperm whales. Using catch per unit effort (cpue) as a metric, in kg/100 hooks, results indicated that depredation depended on both the vessel and the area. More whales associated with vessels from April to August. Sperm whales were also likely to be present when cpue was high, revealing that whales and fishers both knew the most productive fishing areas, but confounding the use of cpue as a metric for depredation. Using a Bayesian mark-recapture analysis and the sightings histories of photo-identified whales, an estimated N = 135 (95% CI 124, 153) sperm whales were associating with vessels in 2014. A spatial model was fitted to 319 longline sets and quantified a 3% loss in cpue, comparable to other global studies on sperm whale depredation. Through all phases of SEASWAP, our understanding of depredation has gained significantly. This successful collaboration should be considered as a model to create partnerships and build collaborations between researchers and fisher people encountering marine mammal interactions with fishing gear.

DOI10.1093/icesjms/fsv090
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