Tests with lanthanide metals were conducted to determine their potential application as a shark repellent in longline fisheries. Six lanthanide metals were tested (cerium (Ce), neodymium (Nd), praseodymium (Pr), cerium-lanthanum mischmetal (CeLa), praseodymium neodymium metal alloy (PrNdA) and praseodymium neodymium mischmetal (PrNdM)) to quantify their voltage and compare dissolution rates in seawater. A behavioral study was used to determine their efficacy in deterring bonnethead and lemon sharks.
Two experiments were conducted to determine if 1) UV illumination reduced green sea turtle capture rates in large mesh gilllnets and 2) what was the impact of UV illumination on target catch rates in bottom-set gillnets. Paired tests were conducted using a control net and an experimental net with UV LEDs placed every 5 m on the floatlines for the sea turtle experiment. In the target catch experiment, inactive LEDs were also placed on the control net at 5 m spacing's.
This paper presents a review of studies on gear technologies used to improve species and size selection in Nephrops trawl fisheries in the North Sea, Irish Sea, Kattegat and Skaggerak. The following categories of gear modifications were analyzed: separator grids, separator/guiding panels, square-mesh panels, capture avoidance designs, and codend modifications. The best gear design depends on the management objectives of the fishery.
At sea trials were conducted comparing the catch composition and weight of standard Nephrops scraper trawls and a new trawl termed the Flip Flap netting Grid trawl (FFG). The FFG includes a 160 mm mesh size netting in the top wing and top sheet netting panels, flip-flap netting grid, and fish outlet hole and 200 mm square mesh panel fitter in front of the fish outlet hole. The FFG trawl resulted in a ~30% reduction (number) of small cod around 32 cm in length but not in fish smaller than this.