Switch off artificial lighting at wild fisheries

How is the evidence assessed?

Study locations

Key messages

  • One study evaluated the effects on freshwater mammals of switching off artificial lights at a wild fishery. The study was in the Puntledge River (Canada).





  • Human-wildlife conflict (1 study): One randomized, controlled study in the Puntledge River found that switching off artificial lights on a bridge did not deter harbour seals from feeding on salmon released from a hatchery.

About key messages

Key messages provide a descriptive index to studies we have found that test this intervention.

Studies are not directly comparable or of equal value. When making decisions based on this evidence, you should consider factors such as study size, study design, reported metrics and relevance of the study to your situation, rather than simply counting the number of studies that support a particular interpretation.

Supporting evidence from individual studies

  1. 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
Please cite as:

Berthinussen, A., Smith, R.K. and Sutherland, W.J. (2021) Marine and Freshwater Mammal Conservation: Global Evidence for the Effects of Interventions. Conservation Evidence Series Synopses. University of Cambridge, Cambridge, UK.

Where has this evidence come from?

List of journals searched by synopsis

All the journals searched for all synopses

Marine and Freshwater Mammal Conservation

This Action forms part of the Action Synopsis:

Marine and Freshwater Mammal Conservation
Marine and Freshwater Mammal Conservation

Marine and Freshwater Mammal Conservation - Published 2021

Marine and Freshwater Mammal Synopsis

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