Install barriers at wild fisheries
Overall effectiveness category Unknown effectiveness (limited evidence)
Number of studies: 1
Background information and definitions
Barriers may be installed at wild fisheries to deter marine and freshwater mammals from feeding on fish. This may reduce 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 installing a ‘cork line’ barrier did not reduce the number of harbour seals Phoca vitulina feeding on migrating juvenile salmon Oncorhynchus spp. under a bridge. Results are not based on assessments of statistical significance. Average numbers of seals feeding on juvenile salmon under the bridge were similar with a ‘cork line’ barrier installed (2–3 seals/30 minutes) and without (2 seals/30 minutes). Seals were observed ‘playing’ with the barrier. In April 1996, a ‘cork line’ (a 60-m rope with cork floats attached at 1 m intervals) was strung across a river below a bridge for an average of 3 h during each of two 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 two nights with the barrier and one randomly selected night without.Study and other actions tested