The experiment evaluated the effectiveness of two types of pingers (Aquamark 100 and Aquamark 200) to reduce the bycatch rate of harbor porpoise (Phocoena phocoena) in a set gillnet fishery in the Black Sea. The study also evaluated the effects of the pingers on catch of target and non-target fish species. There was no significant difference in catch of target and non-target fish species in trials with pingers versus control sets.
Preliminary field studies were carried out on a potentially cetacean-friendly acoustic deterrent system for seals (played using underwater loudspeakers). The “smart seal deterrent signal” produces a startle response in seals rather than an aversion to a very loud noise, and is transmitted at a sound level which is not harmful to seals, even at very close distances.
The study investigated the effects of bait size and hook size on catching efficiency and size selectivity in Icelandic longline fisheries targeting cod (Gadus morhua), haddock (Melanogrammus aeglefinus), tusk (Brosme brosme), ling (Molva molva) and wolffish (Anarhichas lupus). Five sizes of hooks and two sizes of bait were tested. Larger bait (30 grams vs. 10 grams) caught more large fish and fewer small fish of all species, with the exception of ling. Additionally, haddock catches were reduced by 57% when the large bait was used.
The study tested the use of a horizontally divided codend with small square mesh (40mm) and a simple frame to stimulate fish to swim into the upper compartment of a separator trawl. The majority of fish were separated successfully from Nephrops norvegicus, but fish preference for both trawl compartments was uniform. Additionally, separation efficiency was lower for small roundfish and flatfish.
This study investigated the efficiency of a sieve‐panel to separate bycatch species from Norway lobster (Nephrops norvegicus) in trawl gear via mechanical and behavioral means. Four different designs of varying panel mesh size or inclination were tested. The sieving efficiency for Nephrops increased from ~17% to ~71% as mesh size increased, and decreased with increasing carapace length, but did so less as panel inclination and mesh size increased. The sieving efficiency for roundfish was low, while the efficiency for flatfish decreased with fish size.