Catch rates and hook and bait selectivity in longline fishery for Greenland halibut (Reinhardtius hippoglossoides, Walbaum) at East Greenland

Published source details Woll A.K., Boje J., Holst R. & Gundersen A.C. (2001) Catch rates and hook and bait selectivity in longline fishery for Greenland halibut (Reinhardtius hippoglossoides, Walbaum) at East Greenland. Fisheries Research, 51, 237-246.
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This study is summarised as evidence for the following.

	Action	Category
	Use a different bait type Action Link
	Use a different hook type Action Link

Use a different bait type

A replicated study in 1997 in an area of seabed in the Denmark Strait off the east coast of Greenland (Woll et al. 2001) found that baiting hooks in a longline fishery with grenadier (Macrouridae) reduced the catch of unwanted (non-target) fish, and increased the size-selectivity of the target Greenland halibut Reinhardtius hippoglossoides, compared to squid bait (Cephalopoda). The proportion of the total number of hooks with unwanted non-target fish (consisting mostly of roughhead grenadier Macrourus berglax) on them was lower for grenadier bait (1%) than for squid bait (21%). For the target halibut, catch rates were 34% more using grenadier bait. However, the average size of halibut caught were larger (grenadier: 82 cm, squid: 72 cm). Data were collected from deployments of five longline sets (750–1,080 m depth, 5–14 h), by a fishing vessel between July-August 1997. Each set had 1,560 standard hooks, baited alternately with squid or grenadier (species not reported). All halibut and unwanted fish caught were counted, and their lengths recorded.

(Summarised by: Rosslyn McIntyre)
Use a different hook type

A replicated, controlled study in 1997 of deep water in the Denmark Strait off the east coast of Greenland (Woll et al. 2001) found that circle hooks (three types) did not reduce the catch of unwanted roughhead grenadier Macrourus berglax compared to standard hooks in a longline fishery. Overall, the percentage of hooks that caught unwanted grenadier was similar for both hook types (circle hooks: 13%, standard: 14%). However, between the three circle hook types, one caught fewer (11%) compared to the two other types (14–15%). In addition, catch rates of the target commercial species Greenland halibut Reinhardtius hippoglossoides were higher for the same one of three circular hooks compared to the standard hook (circle - blue: 435, standard 281 kg/1,000 hook), and the other two circle hooks were similar (344–368 kg/1,000 hook). Twenty-nine longlines with 1,560 hooks each were deployed from a fishing vessel between July–August 1997. Equal numbers of three types of circle hook and one type of standard hook baited with squid were tested (see original paper for hook specifications). Lines were recovered after 5–14 hours. All fish catch was counted and weighed.

(Summarised by: Rosslyn McIntyre)