Switch off artificial lighting at wild fisheries
Overall effectiveness category Unknown effectiveness (limited evidence)
Number of studies: 1
Background information and definitions
Marine and freshwater mammals, such as seals, may use artificial lighting to feed on fish at wild fisheries at night. Switching off lighting that shines onto the water may reduce mammal predation, thereby reducing human-wildlife conflict and the motivation to use lethal or harmful deterrents.
Supporting evidence from individual studies
A controlled study in 1996 at a site in the Puntledge River, British Columbia, Canada (Yurk & Trites 2000) found that switching off artificial lights on a bridge did not reduce the number of harbour seals Phoca vitulina feeding on migrating juvenile salmon Oncorhynchus spp. Average numbers of seals feeding on salmon under the bridge did not differ significantly with artificial lights switched off (1–10 seals/30 minutes) or on (2–15 seals/30 minutes). In April–May 1996, fourteen artificial lights on a bridge over the river were switched off for four nights. Juvenile salmon were released from a hatchery. Two observers counted seals feeding on salmon using a red-filtered spotlight every 30 minutes from 2100–0300 h during each of the four treatment nights and eight randomly selected nights with no treatments.Study and other actions tested