May 2006
Read the full report on the preliminary assessment of hook sink rates using two branchline types aboard F.V. Ikatere.

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Full report (PDF, 1,200 K)


Time depth recorders (TDRs) were used to compare the rate at which baited hooks sank on two types of branchlines aboard the pelagic longliner, F.V. Ikatere. A normal monofilament branchline was compared with an experimental branchline which had a short terminal wire section with a lure. The mean depth of the hooks 30 seconds after deployment (i.e. at the end of the protection zone
afforded by the tori line) was 8.31 ± 0.56 m (range 5-10 m) for the normal branchlines and 10.56 ± 64 m (range 8-13 m) for the experimental ones. The tori line coverage was estimated as 100-144 m behind the vessel (or c. 30-40 s) at the normal setting speed of 3.6 m/s, which appears to be above average for the vesselís size. Further research should investigate whether the gain in sink rate achieved with the experimental branchline can be replicated on other vessels.

Publication information

Anderson, S. (2004). Preliminary assessment of hook sink rates using two branch line types aboard
F.V. Ikatere. DOC Science Internal Series 190. Department of Conservation, Wellington. 13 p.


Conservation Services Programme
Department of Conservation
PO Box 10-420
Wellington 6143


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