Do rare-earth metals deter spiny dogfish? A feasibility study on the use of electropositive “mischmetal” to reduce the bycatch of Squalus acanthias by hook gear in the Gulf of Maine

Published source details Tallack S.M.L. & Mandelman J.W. (2009) Do rare-earth metals deter spiny dogfish? A feasibility study on the use of electropositive “mischmetal” to reduce the bycatch of Squalus acanthias by hook gear in the Gulf of Maine. ICES Journal of Marine Science, 66, 315-322.
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This study is summarised as evidence for the following.

	Action	Category
	Attach an electropositive deterrent to fishing gear Action Link

Attach an electropositive deterrent to fishing gear

A replicated, controlled study in 2007 in an area of pelagic water in the Gulf of Maine, USA (Tallack & Mandelman 2009) found that attaching mischmetal (a nonmagnetic metal alloy) to commercial and recreational hook fishing gears did not reduce catches of spiny dogfish Squalus acanthias compared to hooks with no mischmetal. Total numbers of dogfish caught with mischmetal present was not statistically different from when mischmetal was absent for commercial longlines (present: 221 fish; absent: 244 fish) or rod and reel (jig) gear (present: 14 fish; absent: 16 fish). Fishing took place in August/September 2007 over 10 days. Pieces of mischmetal (45 × 45 mm and 5 mm thick) were attached 10 cm above the hook and bait on longlines and jigging gears. A total of 21 longlines (2,080 hooks, half with mischmetal and half without) were set for 1–2 h. Jigging using rod and reel took place during the longline deployments. Three rod and reels were configured with two hooks, one with mischmetal attached and one without. Seventy-three jig lines were set (146 baited hooks, half with mischmetal, half without). Captured fish were recorded by hook and bait type.

(Summarised by: Natasha Taylor)