Hook modification to reduce rockfish and Pacific spiny dogfish bycatch in the U.S. West Coast Pacific halibut longline fishery

Hook appendages (16/0 size circle hooks modified with stiff wire extending from their shank at either a 22° or 45° angle in relation to the hooks’ offset and non-offset sides) have the potential to reduce yelloweye rockfish and Pacific spiny dogfish bycatch in the U.S. West Coast Pacific halibut longline fishery. Hooks with a 45° appendage on the non-offset side caught significantly fewer rockfish, Pacific spiny dogfish, and smaller Pacific halibut without impacting legal-sized halibut catch. The appendages change the shape of the hook and greatly reduce the available opening for a fish’s mouth to engage with the hook, which may make it more difficult for fishes with vertical mouths (e.g., dogfish and rockfishes) than fish with horizontal mouths (e.g., halibut) to be caught using this method.