Premium
Studying small purse‐seine vessel fishing behavior with tuna catch data: Implications for eastern Pacific Ocean dolphin conservation
Author(s) -
LennertCody Cleridy E.,
Rusin Jeremy D.,
Maunder Mark N.,
Everett Edward H.,
Largacha Delgado Erick D.,
Tomlinson Patrick K.
Publication year - 2013
Publication title -
marine mammal science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.723
H-Index - 78
eISSN - 1748-7692
pISSN - 0824-0469
DOI - 10.1111/j.1748-7692.2012.00608.x
Subject(s) - tuna , fishery , fishing , yellowfin tuna , bycatch , skipjack tuna , sampling (signal processing) , geography , pacific ocean , population , port (circuit theory) , oceanography , biology , fish <actinopterygii> , geology , demography , engineering , filter (signal processing) , sociology , electrical engineering
Despite achievements in dolphin conservation for the tuna purse‐seine fishery of the eastern Pacific Ocean, debate continues about the magnitude and importance of dolphin mortality caused by small (unobserved) vessels. In‐port sampling of tuna catch size composition is a potentially cost‐effective means of identifying unobserved vessels that may be catching tunas associated with dolphins because yellowfin tuna caught in association with dolphins are larger, on average, than those caught in other types of purse‐seine sets. A classification algorithm to predict purse‐seine set type (“dolphin” vs . “nondolphin”) was built from port‐sampling data on yellowfin tuna length‐frequencies and the date and location of fishing of large (observed) vessels. This classification algorithm was used to screen the port‐sampling data of small vessels collected during 2006‐2009, assuming the fishing practices of the two groups resulted in similar catch characteristics. From these results, hypothetical time series of dolphin mortality for small vessels were constructed and incorporated into a population dynamics model, along with mortalities of large vessels. Results suggest that any dolphin mortality of small vessels is unlikely to be substantially affecting trends in dolphin abundance. These results underscore the importance of in‐port sampling, in combination with at‐sea observation and fishery‐independent surveys, to effective management.