Multi-methods approach to characterizing the magnitude, impact, and spatial risk of Irrawaddy dolphin (Orcaella brevirostris) bycatch in small-scale fisheries in Malampaya Sound, Philippines

TitleMulti-methods approach to characterizing the magnitude, impact, and spatial risk of Irrawaddy dolphin (Orcaella brevirostris) bycatch in small-scale fisheries in Malampaya Sound, Philippines
Publication TypeJournal Article
Year of Publication2016
AuthorsWhitty T.S
JournalMarine Mammal Science
Volume32
Pagination1022-1043
Date Published2016/07
Type of ArticleArticle
ISBN Number0824-0469
Accession NumberWOS:000385006800012
KeywordsAsia; bottle-nosed-dolphin; bycatch; cetaceans; conservation; dolphin; entanglements; interview; Irrawaddy; Orcaella brevirostris; population; risk; small-scale fisheries; spatial overlap; tursiops-truncatus; whales
Abstract

Addressing the urgent conservation threat of marine mammal bycatch in small-scale fisheries requires information on bycatch magnitude, gear types, population impacts, and risk. However, data on these proximate attributes are widely lacking in developing countries. This study used a multi-methods approach integrating boat surveys and interviews with fishermen (n = 526) to assess proximate attributes of bycatch for the Critically Endangered subpopulation of Irrawaddy dolphins (Orcaella brevirostris) in Malampaya Sound, Philippines. Given an updated population estimate of 35 individuals (CV = 22.9%), the estimated rate of bycatch fatalities exceeds the potential biological removal rate. Spatial overlap scores were calculated to characterize overlap between dolphins and fisheries as a proxy of bycatch risk. These scores identified particularly high risk areas that could be prioritized for gear bans. However, completely reducing bycatch risk would require more widespread bans beyond these high risk areas. Implementing gear restrictions will be immensely challenging, given serious obstacles to fisheries management at this site. The multi-methods approach describes the urgency of the bycatch problem and the changes required for mitigation, setting the stage for identifying and evaluating potential solutions. It can be readily applied to developing country sites to guide more efficient and complete data collection and conservation efforts.

DOI10.1111/mms.12322
Short TitleMar. Mamm. Sci.
Student Publication: 
No