Incidental c of seabirds by Japanese southern bluefin tuna longline vessels in New Zealand waters, 1988-1992
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Published source details
Murray T.E., Bartle J.A., Kalish S.R. & Taylor P.R. (1993) Incidental c of seabirds by Japanese southern bluefin tuna longline vessels in New Zealand waters, 1988-1992. Bird Conservation International, 3, 181-210.
Published source details Murray T.E., Bartle J.A., Kalish S.R. & Taylor P.R. (1993) Incidental c of seabirds by Japanese southern bluefin tuna longline vessels in New Zealand waters, 1988-1992. Bird Conservation International, 3, 181-210.
Actions
This study is summarised as evidence for the following.
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Set longlines at night to reduce seabird bycatch Action Link |
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Use streamer lines to reduce seabird bycatch on longlines Action Link |
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Set longlines at night to reduce seabird bycatch
A study using data from bluefin tuna Thunnus thynnus boats operating off New Zealand between 1988 and 1992 (Murray et al. 1993) found that the effects of night-setting on seabird bycatch rates varied between fishing areas, probably due to different species making up the majority of bycatch. In southern areas, 87% of 47 identified birds caught were albatrosses and 73% of 88 birds were caught between 0600 and 1400 (when 41% of 1,009 lines were set). In contrast, in northern fishing grounds, where 59% of 75 identified birds were petrels, 44% of the 181 birds caught were hooked within 90 minutes of dawn or dusk and 42% were caught at night (when 54% of 1,180 lines were set).
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Use streamer lines to reduce seabird bycatch on longlines
A comparative study of ten bluefin tuna Thunnus thynnus longlining boats fishing off New Zealand in 1992 (Murray et al. 1993), found that none of five vessels that used a streamer line over 51% of the time caught any birds (over 100 line sets). The remaining five boats used streamer lines for less than 12% of the time and caught 14 birds over 157 sets. However, the authors cautioned that these results were preliminary, with limited observer coverage, no controls and no statistical tests.
Output references
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