New branch line weighting regimes reduce risk of seabird mortality in the Australian pelagic longline fishery without affecting fish catch

Authors: 

Robertson, G., Candy, S. and Hall, S.

Year: 

2012

Journal/Publisher Name: 

Western and Central Pacific Fisheries Commission

Volume (Issue #): 

WCPFC-SC8-2012/EB-WB-09

Page #s: 

19

Contact information: 

Australian Antarctic Division 203 Channel Highway Kingston, Tasmania Australia 7050
Summary: 

Two new branch weighting techniques were tested aboard Australian pelagic longline vessels to determine their effect on catch rates of both target and non-target species and their potential use for seabird mitigation.  The two new branch lines included one with a 120 g lead weight < or equal to 2 m from the hook or a branch line with a 40 g lead weight placed at the hook.  There were no significant differences in catch rates for either the main target (yellowfin tuna, albacore tuna, bigeye tuna, swordfish and mahi mahi) or non-target species (sharks) between the industry standard branch line and either of the new ones.  However, the new branch line with the 40 g weight sank more quickly than the industry standard, improved crew safety and reduced the amount of time spent constructing gear. Therefore this option may have the potential to reduce seabird interactions without affecting catch rates of target species.