The accidental/incidental capture of seabirds by longline gear may be causing a significant decline in the numbers of some species (most notably albatross Diomedea sp) in the Southern Oceans.
In response to the sea bird problem, the New Zealand Department of Conservation funded a programme in 1996 to develop a device to set baits underwater on commercial longliners.
Trials on two U tube devices are reported in this document. One with the tube opening facing forward was unsuccessful ,in flushing bait to the setting depth, however a backward facing U tube succeeded in flushing the bait on all trials to the setting depth of 1.5 metres.
A second trial was undertaken with the backward facing U tube. On all trials the U tube * successfully flushed the baits to the required three metre depth.
The U tube is a simple mechanical device requiring only one additional item of equipment - a deckhose. The device requires minimal operator skill, and is easy to build and maintain.
The U tube has the potential to set baits at greater than three metres. However, this capability has not been tested. Further study is required to test the device on commercial tuna vessel operating conditions and to assess the effectiveness of the device in thwarting seabirds from capturing the baits underwater.
Document Number:
WG-FSA-97/53
Agenda Item(s)
Abstract