Action: Move fish-eating birds to reduce conflict with fishermen
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A single before-and-after study in the USA found that Caspian tern Sterna caspia chicks had a lower proportion of commercial fish in their diet following the movement of the colony away from an important fishery.
Supporting evidence from individual studies
A before-and-after study in 1999-2001 on two small islands in the Columbia River Estuary, Oregon, USA (Roby et al. 2002), found that various interventions led to the relocation of a Caspian tern Sterna caspia colony (8,900 pairs in total) away from an important fishery. Tern chicks had a significantly lower proportion of juvenile commercial fish (such as coho salmon Oncorhynchus kisutch, steelhead O. mykiss and chinook salmon O. tshawytscha) in their diet following the movement of the colony to East Sand Island, compared with its original position on Rice Island (commercial fish making up 42% of the diet on East Sand Island vs. 83% on Rice Island, approximately 120 bill-loads sampled at each site each year). The predation of commercial fish by terns was a significant source of conflict with local fishermen, and translocation may well have reduced this conflict. Tern productivity was significantly higher at East Island than Rice Island in every year of the study. Individual interventions are discussed in ‘Use decoys to attract birds to new nesting areas’, ‘Use vocalisations to attract birds to new nesting areas’, ‘Control avian predators on islands’, ‘Habitat restoration/creation – intertidal habitats’ and ‘Translocations - Alter habitat to encourage birds to leave an area’.