Electrochemical properties of lanthanide metals in relation to their application as shark repellents

Published source details McCutcheon S.M. & Kajiura S.M. (2013) Electrochemical properties of lanthanide metals in relation to their application as shark repellents. Fisheries Research, 147, 47-54.
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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, randomized study in 2010–2011 in a laboratory in Florida, USA (McCutcheon & Kaijura 2013) found that a potentially deterrent metal (neodymium) attached to bait did not reduce the incidence of bait capture by bonnethead shark Sphyrna tiburuo or young lemon shark Negaprion brevirostris, compared to three non-deterrent materials. Across trials, the percentages of bites taken to remove bait from the neodymium was similar to all three other materials for both bonnetheads (neodymium: 27–32%, acrylic: 23–25%, lead: 22–23%, and stainless steel: 23–27%) and young lemon sharks (neodymium: 35%, acrylic: 23%, lead: 23%, and stainless steel: 21%). A total of 12 bonnethead sharks and 13 immature lemon sharks caught by gillnet and hook and line fishing in September 2010–August 2011, were maintained in an aquarium. After one week to acclimatise, sharks were starved for 48 h. Four equal-sized (2.5 × 2.5 × 0.6 cm) pieces of neodymium (the test material), acrylic, lead, and stainless steel were put in a shallow (0.9 m depth × 4.6 m diameter) tank fixed to a 1m²acrylic plate. Position of each material was randomized each trial. Sharks were introduced to the tank and the baited (shrimp for bonnethead, mullet and herring for lemon sharks) plates they bit were recorded. Bonnethead sharks were tested individually and in groups of 2–4 and lemon sharks were tested only in groups of 2–4 (see original paper for full methods).

(Summarised by: Chris Barrett)