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Providing evidence to improve practice

Individual study: Movements of sea otters relocated along the California coast

Published source details

Ralls K., Siniff D.B., Doroff A. & Mercure A. (1992) Movements of sea otters relocated along the California coast. Marine Mammal Science, 8, 178-184


This study is summarised as evidence for the intervention(s) shown on the right. The icon shows which synopsis it is relevant to.

Translocate mammals away from site contaminated by oil spill Terrestrial Mammal Conservation

A study in 1988–1989 in coastal waters of California, USA (Ralls et al. 1992) found that after being translocated in a trial of responses to a hypothetical pollution incident, most sea-otters Enhydra lutris survived for the duration of monitoring and did not return to their capture location. Seventeen of 19 translocated sea otters survived for at least 16–87 days after release. Two died at the release site, after 21 and 28 days after release. Five of 19 translocated sea otters were recorded back at their capture location during the monitoring period. Twelve were last recorded at a site 27 km from the release site. Nineteen sea otters were caught between May 1988 and May 1989 and were released 291 km further north. Nine were released immediately on arrival and 10 were held for 48 hours in floating pens before release. Sea otters were radio-tracked from the ground or air for 16–87 days after release.

(Summarised by Nick Littlewood)

Use holding pens at release site prior to release of translocated mammals Terrestrial Mammal Conservation

A study in 1988–1989 in coastal waters of California, USA (Ralls et al. 1992) found that after being held in pens at the release site, fewer translocated sea otters Enhydra lutris returned to the capture site compared to those released immediately after translocation. No statistical analyses were performed. None of 10 sea otters held in release pens returned to the capture site and all remained within 27 km for the duration of monitoring. Five of nine released immediately on arrival returned to the capture site. Nineteen sea otters (18 male, one female) were caught between May 1988 and May 1989 and were released 291 km further north. Nine were released immediately on arrival and 10 were held for 48 hours in floating pens before release. Sea otters were radio-tracked from the ground or air for 16–87 days after release.

(Summarised by Nick Littlewood)