Evaluating post-intervention survival of free-ranging odontocete cetaceans

Published source details Wells R.S., Fauquier D.A., Gulland F.M.D., Townsend F.I. & DiGiovanni R.A. (2013) Evaluating post-intervention survival of free-ranging odontocete cetaceans. Marine Mammal Science, 29, 463-483.
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This study is summarised as evidence for the following.

	Action	Category
	Remove derelict fishing gear from mammals found entangled Action Link
	Rescue and release stranded or trapped marine and freshwater mammals Action Link
	Rehabilitate and release injured, sick or weak marine and freshwater mammals Action Link

Remove derelict fishing gear from mammals found entangled

A review of three case studies in 2003–2010 in the North Atlantic Ocean, USA (Wells et al. 2013) found that three common bottlenose dolphins Tursiops truncatus entangled in derelict fishing gear that were rescued and released survived for at least 1–4 years. All of three rescued and disentangled dolphins (including one calf) were successfully tracked for 365–1,541 days after release. The dolphins (two males, one female calf) were found entangled in derelict fishing gear in 2003, 2006 and 2008. They were disentangled, treated, transported to appropriate habitats, and released immediately. All three dolphins were radio-tracked after release. Details of monitoring methods were not reported. Data were from published and unpublished studies.

(Summarised by: Anna Berthinussen)
Rescue and release stranded or trapped marine and freshwater mammals

A review of seven case studies in 2006–2010 in the North Atlantic Ocean, USA (Wells et al. 2013) found that five of seven trapped common bottlenose dolphins Tursiops truncatus that were rescued and released survived for at least 1–3 years. Five of seven rescued dolphins were successfully tracked for 365–1,040 days after release. Two other trapped and rescued dolphins were tracked for <1–2 days after release. One stranded and died, the other was considered unlikely to have survived. The dolphins (three males, three females, one unknown) were found trapped out of their natural habitats in 2006, 2007 and 2010. They were rescued, treated, transported to appropriate habitats, and released immediately. All seven dolphins were radio-tracked after release. Details of monitoring methods were not reported. Data were from published and unpublished studies.

(Summarised by: Anna Berthinussen)
Rehabilitate and release injured, sick or weak marine and freshwater mammals

A review of 56 case studies in 1986–2008 in the North Atlantic Ocean and North Pacific Ocean, USA (Wells et al. 2013) found that approximately one third of rehabilitated common bottlenose dolphins Tursiops truncatus and other small cetacean species that were released back into the wild survived for at least six weeks and had normal behaviour. For common bottlenose dolphins, seven of 20 releases (35%) were considered successful (the dolphin was tracked for at least six weeks after release with normal behaviour for the species). Eight releases (40%) had unknown success, and five (25%) failed (the dolphin died, re-stranded or had abnormal behaviour). For other small cetaceans (including other dolphin species, porpoises and whales; see original paper for details), 13 of 36 releases (36%) were considered successful, 22 releases (61%) had unknown success, and one (3%) failed. The common bottlenose dolphins were found stranded (13 dolphins), trapped out of their natural habitats (three), entangled in fishing gear (three) or orphaned (one) in 1992–2008 and rehabilitated for 37–225 days before release. Thirty-six other small cetaceans were found stranded in 1986–2007 and rehabilitated for 35–394 days before release. Data were from published and unpublished studies. Eleven studies have also been summarized individually. Details of monitoring methods were not reported.

(Summarised by: Anna Berthinussen)