Position statement on the release of long-term captive cetaceans

Introduction

Any reintroduction effort, regardless of species, should be regarded as a scientific undertaking.

The release into the wild of captive bred or long-term captive animals of a great variety of species is fraught with a number of difficulties. These include the presence (or lack thereof) of a suitable habitat and other individuals or groups of animals of the same species with which the introduced animals might interact. The introduced animals must be able to avoid predators and to fend for themselves, although additional provisioning in the early stages of the release can be considered. The risk of disease transmission both from the introduced animals to the receiving population and vice versa must be minimized (NMFS, 1996a), since this may endanger the wild population. It is imperative to release animals back to the same stock from which they came since genetic mixing may have unknown long-term effects. Social behaviour and natural history should be taken into account as well. This issue can be complicated if the animals have been in captivity for a long period or are captive-born; the composition of the original stock may have radically changed or may have moved to an unknown location. Genetic factors are less important if the species has become extinct in the wild over all or a major part of its previous range. For these and other reasons the reintroduction into the wild of long-term or captive-bred species needs very careful consideration.

Release of cetaceans

A number of release schemes have been aimed at re-establishing wild populations in areas from which the species has been eliminated or at restocking depleted populations. For these situations, guidelines have already been established (IUCN, 1987; UFAW, 1992). However, these situations are quite different from the situation with cetaceans maintained in human care where the animals to be released generally do not belong to endangered species or do not come from depleted populations. (The only exception to this is the Baiji in China). For this reason the release of cetaceans should not be considered a conservation-related release and the IUCN and UFAW guidelines do not apply.

There have been quite a number of releases into the wild of long-term captive cetaceans, mainly in the U.S.A but also elsewhere in the world. The animals released have usually been bottlenose dolphins (Tursiops truncatus) because there are more of these in captivity than any other species of cetaceans. In some cases the release was accidental, in other cases the release was poorly prepared and did not include a follow-up. Thus the fate of the animals involved remains unknown. Unless we know the fate of the animals we cannot determine whether or not they are able to cope with the wild situation.

A few other releases that have been planned over a considerable period of time, appeared to have been well organised with consideration of the points raised in the introduction and the required training of the animals (as outlined in Brill and Friedl, 1993). However, to date only the release of two male dolphins after only 2 years in captivity has been demonstrated to be successful (Wells et al, 1998). In other cases, animals had to be recaptured in poor condition and at least one captive-born calf is known to have died after release (NMFS, 1996b; Gales and Waples, 1993). However, in most cases, the fate of the animals remains unknown due to a lack of confirmed sightings of the animals.

Reintroduction should not be seen as an option for the management of the cetacean population in human care (Brill and Friedl, 1993). We should continue to provide all captive marine mammals with the highest quality care for the duration of their lives.

Position statement

The European Association for Aquatic Mammals is of the opinion that the release into the wild of long-term captive cetaceans or those bred in captivity is not needed for conservation reasons. There is a general lack of proof that cetaceans do well after a release and therefore any release attempt should be considered an experiment. The European Association for Aquatic Mammals therefore does not support any release attempts of long-term captive and captive-born cetaceans. The success of reintroducing cetaceans to the wild will depend upon resources, methodologies and technologies which still need to be tested.

Nothing in this document relates to the release of cetaceans held short-term when found injured, debilitated, stranded or in need of human intervention for whatever reason. For guidelines regarding rehabilitated stranded animals see St. Aubin et al (1996).

References

D. J. St. Aubin, J.R. Geraci and V.J. Lounsbury (1996)

Rescue, Rehabilitation and Release of Marine Mammals: An Analysis of Current Views and Practices. NOAA Technical Memorandum NMFS-OPR-8, July 1996

R.L. Brill and W.A. Friedl (1993)

Reintroduction to the Wild as an Option for Managing Navy Marine Mammals
NCCOSC, RDT&E Division (NRaD) Technical Report 1549

N. Gales and K. Waples (1993)

The rehabilitation and release of bottlenose dolphins from Atlantis Marine Park, Western Australia
Aquatic Mammals 19(2): 49-59

IUCN (International Union for Conservation of Nature and Natural Resources) (1987)

Translocation of living organism
IUCN Position Statement, Sept 4. 1987
International Union for Conservation of Nature and Natural Resources
Avenue du Mont-Blanc
CH-1196 Gland
Switzerland

NMFS (National Marine Fisheries Service) (1996a)

What should we know before we free Willy?
MMPA Bulletin 8:1-2

NMFS (National Marine Fisheries Service) (1996b)

Former Navy dolphins rescued in Florida Keys
MMPA Bulletin 9:3

UFAW (Universities Federation for Animal Welfare) (1992)

Welfare guidelines for the re-introduction of captive bred mammals to the wild
Universities Federation for Animal Welfare
8 Hamilton Close, South Mimms, Potters Bar
Hertfordshire EN6 3QD
United Kingdom

R.S. Wells, K. Bassos-Hull and K.S. Norris (1998)

Experimental return to the wild of two bottlenose dolphins
Marine Mammal Science 14(1): 51-71