A desk-based study was conducted to evaluate 'conservation-relevant elements' of local governments involved in coastal and aquatic resource management, particularly bycatch mitigation. Four sites were looked at: 1) Trat, Thailand, 2) Mahakam River, Indonesia, 3) Malampaya Sound Philippines and 4) Guimaras and Iloilo Straits, Philippines. The species of interest was Irrawaddy dolphin (Orcaella brevirostris) caught in small-scale fisheries.
Two models of high field strength neodymium magnets (N35-Ni and N35-NdFeB types) were tested to determine their ability to deter sharks incidentally captured in Spanish and Portuguese longline fisheries operating in the Northeast Atlantic Ocean. The main shark species tested was blue shark (Prionace glauca). The larger magnet was 26 mm X 11 mm X 12 mm, 0.885 T and the smaller magnet was 20 mm X 13 mm X 15 mm, 0.464 t. Field test results indicated the magnets do not reduce blue shark catch rates and may instead have an attractive effect.
This article describes the design and fabrication of a prototype rope-less fishing system that might be used in the Gulf of Maine lobster fishery. Rope-less fishing gear, which secures vertical fishing lines to the bottom until they are released for hauling, is a potential mitigation measure to reduce vertical line entanglements of marine mammals including North Atlantic right whales, along with leatherback sea turtles. The prototypes consists of a flotation line spool capable of holding up to 900 m of 1/2 in line.
Acoustic deterrents were tested for their ability to deter humpback whales (Megaptera novaeangliae) from potential sources of entanglement. Low frequency (3 kHz, 135 +/- 5 db, 5 s emission interval and 400 ms emission duration) alarms were tested. Alarms were placed in the center of the northerly migration path (southern hemisphere) of humpback whales. Observers, who were unaware of the alarm status (i.e. on/off) tracked the pods as they passed the alarms. Sixty percent of the pods (N=137) passed within the assumed detectable range (500 m) of the alarm.
This study investigated the impact of rope polymer type, breaking strength and diameter in relation to the injury severity of entangled baleen whales, primarily North Atlantic Right whales (Eubalaena glacialis). Fishing gear removed from live and dead entangled whales from the US East Coast and Canadian Maritimes region between 1994 and 2010 were included in this study. Average tested breaking strength of removed rope was 2,616 bs, 26% below strength at manufacture. Median rope diameter was 3/8 in.