The influence of environmental factors and mitigation measures on by-catch rates of seabirds by Japanese longline fishing vessels in the Australian region

Published source details Klaer N. & Polacheck T. (1998) The influence of environmental factors and mitigation measures on by-catch rates of seabirds by Japanese longline fishing vessels in the Australian region. Emu, 98, 305-316.
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This study is summarised as evidence for the following.

	Action	Category
	Thaw bait before setting lines to reduce seabird bycatch Action Link
	Use bait throwers to reduce seabird bycatch Action Link
	Set longlines at night to reduce seabird bycatch Action Link

Thaw bait before setting lines to reduce seabird bycatch

An analysis of data from 86 longlining vessels operating around Tasmania, Australia, between April 1992 and March 1995 (Klaer & Polacheck 1998) and studying a total of 141 line sets, found that sets that using partially or completely thawed bait had significantly lower bycatch rates, compared to sets using unthawed bait. This study is also described in ‘Set longlines at night to reduce seabird bycatch’ and ‘Use bait throwers to reduce seabird bycatch’.
Use bait throwers to reduce seabird bycatch

A comparative analysis of data from 86 longlining vessels operating around Tasmania, Australia, between April 1992 and March 1995 (Klaer & Polacheck 1998) and studying a total of 141 line sets, found that sets that using a bait thrower had significantly lower seabird bycatch rates, compared to sets without a thrower. This study is also described in ‘Set longlines at night to reduce seabird bycatch’ and ‘Thaw bait to reduce seabird bycatch’.
Set longlines at night to reduce seabird bycatch

A replicated, controlled study using data from 86 longlining vessels operating in Australian waters, between April 1992 and March 1995 (Klaer & Polacheck 1998) found that longlines set at night caught approximately five times fewer seabirds than those set during the day (1.0 birds/1,000 hooks for 924 line-sets set at night vs. 4.8 birds/1,000 hooks for 1,372 line-sets set during the day). The difference was greatest on nights close to a new moon (with 7% of the bycatch rates of day sets), but there were always significant reductions (sets on full moon nights had approximately one-third the bycatch rates of day sets). This study does not discuss which birds were caught, but previous studies have shown that this fishery catches mainly albatross. This study is also discussed in ‘Use bait throwers to reduce seabird bycatch’ and ‘Thaw bait to reduce seabird bycatch’.