Returning dolphins from zoological collections to the wild?

 

Returning dolphins from zoological collections to the wild?

One of the claims often made by those who oppose zoological collections, particularly facilities that house dolphins, is that these animals should simply be released back into the wild. This is a rather glib position that overlooks the serious biological, social, and practical challenges involved.

First, the vast majority of bottlenose dolphins held in zoological collections today originate from captive-breeding programmes rather than from wild capture. This creates a fundamental constraint on release, as their family groups exist within these collections rather than in natural wild populations.

As of 11 March 2025, there are 415 dolphins held in 32 facilities in the United States. Excluding killer whales, the figures for dolphin species are as follows:

Wild-caught: 55 (13%)
Captive-born: 325 (78%)
Rescued: 35 (8%)

A European snapshot can be taken from Harderwijk Marine Mammal Park, where the bottlenose dolphin inventory comprises:

Wild-caught: 3 (10%), captured in 1979, 1980, and 1989
Captive-born: 26 (90%)

Some European facilities, such as Planète Sauvage, hold dolphin populations that are entirely derived from captive-breeding programmes.

Looking specifically at resident bottlenose dolphins at SeaWorld parks in the United States, 6 animals (6%) were taken from the wild in 1972, 1978, 1982, and 1987, while 98 (94%) were obtained through captive breeding. Five animals at SeaWorld are listed as rescued and are not included in the above statistics. See the explanatory note below regarding this status and what it entails.

Activist groups often describe these animals as having been “snatched from their families”. However, dolphins born in zoological collections typically remain with their family groups. It is also important to consider the natural fusion–fission social structure of bottlenose dolphins when assessing social groupings in both wild and managed settings. An explanatory note on fusion–fission societies is provided below.

Second, even when considering the release of wild-caught animals, guidance from organisations such as the International Union for the Conservation of Nature (IUCN) is clear. Individuals should, wherever possible, be returned to their original area of capture as part of any release or rewilding effort.

And what of killer whales?
Based on the Cetabase Global Orca List dataset exported on December 2025 there were 53 living captive killer whales: 

Captured: 22 (41.5%)
Born: 30 (56.6%)
Rescue/non-releasable: 1 (1.9%)

The majority of these animals were therefore born in zoological collections and would not be appropriate candidates for release. The 41.5% that were wild-caught have also been in captivity for extended periods, which substantially alters their behaviour and survival skills. This was clearly demonstrated during the failed attempt to release Keiko, the killer whale. Despite substantial financial investment, he never integrated with wild killer whales. After being left to fend for himself, he swam to a Norwegian fjord, actively sought human contact, and begged for food. He died shortly afterwards from pneumonia.

See: Kieko the Killer Whale blog.

Turning to the question of sanctuaries, only one currently exists, housing two beluga whales. This facility has faced significant difficulties during the six years the animals have been resident there. For the past two years, they have been confined to an indoor pool at a Sea Life tourist centre. The bay intended to function as the sanctuary can only be used during the summer months, and the animals must be removed for safety reasons affecting both them and their carers. At least one of the belugas became ill while in the bay, probably as a result of stress.

See: Beluga Sanctuary Blog

A sanctuary proposed for Canada remains many years away, even if it ultimately proves feasible and sufficient funding for construction and long-term operation can be secured.


Explanatory notes

Rescue and rehabilitation in the United States
In the United States, any dolphin that strands or enters rehabilitation falls under the federal authority of NOAA Fisheries, which enforces the Marine Mammal Protection Act. Decisions on whether an animal is deemed non-releasable, whether due to health concerns or because it stranded as a neonate, are made by NOAA rather than by the facilities that carry out rescue and rehabilitation.

Fusion–fission societies explained
A fusion–fission society is a form of social organisation in which group membership is fluid. Animals periodically come together into larger groups for activities such as feeding, travel, or protection, and then separate into smaller subgroups or individuals as conditions change. This flexibility allows a balance between the benefits of cooperation, such as increased safety and information sharing, and the costs of competition, including limited food resources or social conflict.

Bottlenose dolphins are a well-established example of fusion–fission dynamics. They may form large pods when hunting schools of fish or navigating predator-rich waters, but these aggregations are not permanent. Smaller subgroups, sometimes consisting of only a few individuals, frequently break off to forage independently or engage in social behaviour. Group membership is not fixed, creating a constantly shifting social landscape.

Male dolphins often form long-term alliances with one or two partners, although these alliances may temporarily merge with others during competition for mates or defence against rivals. Females tend to associate more loosely, often moving between groups depending on reproductive status or calf-rearing requirements.

CetaBase
As mentioned, the data presented here are drawn from the CetaBase website, which is widely regarded as an objective and accurate source of information on cetaceans in human care.

References

IUCN/SSC (2013). Guidelines for Reintroductions and Other Conservation Translocations. Version 1.0. Gland, Switzerland: IUCN Species Survival Commission.

Carver, S., Convery, I., Hawkins, S., Hertel, S., Fallon, J., Lyons, K., Beyers, R., Locquet, A., Derham, T. and Kun, Z. (eds.) (2025). Guidelines for rewilding. Gland, Switzerland: IUCN.

Marine Animal Welfare (2025) Releasing cetaceans back to the wild. Available at: https://marineanimalwelfare.blogspot.com/p/releasing-cetaceans-back-to-wild.html (Accessed: 14 December 2025).

The History of Seal Rescue and Rehabilitation in the United Kingdom

The original Cornish Seal Sanctuary, St Agnes

Seal rescue in the United Kingdom has grown from small, locally driven efforts into a coordinated national system that now supports hundreds of animals each year. Two centers stand out for their longevity and consistency: the Cornish Seal Sanctuary in Cornwall. and Natureland Seal Sanctuary in Skegness. Their histories underpin almost all modern developments in UK marine-mammal welfare.

Ken Jones outside the new seal hospital in Gweek in 1976.

The Cornish Seal Sanctuary

In 1958, the first organised rescue effort in Cornwall began in St Agnes, led by individuals concerned about increasing reports of stranded pups on the county’s storm-exposed beaches. This early work laid the groundwork for what would eventually become the Cornish Seal Sanctuary.

By the 1970s, the operation had formalised and later moved to its permanent home at Gweek. The site offered the space and facilities needed for proper rehabilitation—deep pools for swimming practice, veterinary areas, quarantine sections and dedicated pup-rearing units.

The sanctuary became one of the best-known facilities of its kind in Europe. Its staff and volunteers refined methods for tube-feeding emaciated pups, treating injuries caused by entanglement, and managing the complex process of reintroducing animals to open water. Many of the protocols used today across the UK trace their origins to the systems developed here.

The Cornish Seal Sanctuary’s work remains intensive. Cornwall’s exposed Atlantic coastline produces high annual strandings, particularly during winter storms. The sanctuary’s long history means that it still receives a substantial number of calls from the public, fishermen and coastal authorities.

Natureland Seal Sanctuary, Skegness

Natureland’s story began in 1965, when John Yeadon with his business partner Alan Dales took over  a small  animal attraction that quickly became known for something far more important than tourism. The small marine zoo began taking in exhausted or injured grey seal pups washed ashore along the Lincolnshire coast. Their work soon evolved into a structured rehabilitation programme, and Natureland became one of the earliest facilities in the UK to run a repeatable “rescue–recover–release” model.

Over the decades it gained a reputation for reliability. The Lincolnshire coastline, particularly around Donna Nook, sees significant grey seal breeding each year, meaning large numbers of pups are vulnerable to storm surges, separation and malnutrition. Natureland’s ability to step in season after season has made it one of the UK’s steadier rescue centres. Today, it is still family-run, and still releasing seals back into the North Sea after months of specialist care.

Seal sanctuary celebrates diamond anniversary 
© 2025 County Life Ltd.

  

Expanding Capacity: Volunteer Networks and New Facilities

While Skegness and Gweek formed the backbone of UK seal rehabilitation, the work eventually outgrew two main centres. Several developments helped meet this increasing demand:

British Divers Marine Life Rescue (BDMLR)

Formed in the late 1980s, BDMLR created the first nationwide network able to respond rapidly to strandings. Trained volunteers now attend callouts along nearly the entire UK coastline, stabilising seals before transferring them to specialist hospitals.

More recently BDMLR opened its Cornwall Seal Hospital, providing high-dependency care and relieving pressure on Gweek during busy pup seasons.

South Essex Wildlife Hospital 

South Essex Wildlife Hospital in Orsett opened a dedicated seal-rescue unit in 2023, filling a major gap in coverage along the east and south-east coasts. The new facility includes purpose-built pools, filtration systems, and veterinary areas designed for treating grey and common seals, and it is overseen by founder Sue Schwar with veterinary support from Tom Linsel. The hospital now handles an increasing number of stranded or displaced pups—often from the Thames Estuary or inland waterways—and provides stabilisation, rehabilitation and release for cases that previously had to be transported long distances to established sanctuaries. 

Welsh Mountain Zoo – Seal Rescue Unit

The Welsh Mountain Zoo in Colwyn Bay hosts a dedicated seal-rescue unit (sometimes referred to as the “North Wales Seal Rescue Centre”). Since the zoo’s own founding in the early 1960s, staff have occasionally admitted injured or orphaned native wildlife — but in 1997 they opened a formal facility for marine mammals, featuring two filtered pools and an indoor intensive-care unit. 

Kipper the first successful rehabilitation of a rescued seal in 1982

Over the years the unit has taken in young grey (and occasionally common) seal pups stranded along the Welsh coast — often in collaboration with RSPCA or other responding charities.  Once in care, pups receive tube-feeding or hand-feeding until they regain condition; as they improve they are moved to deeper outdoor pools to practise swimming and diving. 

Welsh Marine Life Rescue (WMLR)

Operating mainly in south-west Wales, WMLR handles first response, treatment and occasional rehabilitation for seals along the Pembrokeshire coast. Their presence has been vital in a region without a large dedicated sanctuary.

Mablethorpe Seal Sanctuary

On the Lincolnshire coast, the Mablethorpe Seal Sanctuary & Wildlife Centre has been caring for seals since 1974. Over the years, it has treated more than 1,000 grey and harbour seals, many of them orphaned or injured pups from nearby colonies such as Donna Nook. Visitors can glimpse the rescue process first‑hand: pups are stabilised with fluids and antibiotics, hand‑ or tube‑fed, and gradually introduced to pools until they are strong enough to return to the sea.  

Not every seal can be released, and those that remain become permanent residents — ambassadors who help tell the story of their species and the challenges they face. Alongside seals, the centre also rescues seabirds and other native wildlife, reflecting its broad commitment to animal welfare. By handling local rescues, Mablethorpe eases pressure on larger sanctuaries and shortens transport times for distressed pups. For the public, it offers a chance to learn about seal biology, conservation threats, and how donations directly support ongoing care. During storm seasons, the sanctuary often operates at full capacity, making community support vital to its mission.  

Teesmouth Seal Rescue & Coastal Conservation Centre

Further north, the Teesmouth Seal Conservation Trust (TSCT) is creating a dedicated rescue and rehabilitation centre at South Gare, Redcar. In 2024, the charity secured a 30‑year lease on a former lifeboat station, transforming it into the region’s first seal hospital. Plans include heated dry pens for newly admitted pups, seawater “wet pens” for growing seals, and larger pools for swim training before release. The facility will also house food preparation areas, offices, and a top‑floor space for training and community engagement.  

The centre will focus on harbour and grey seals from the Tees estuary — a population that has rebounded but remains vulnerable to disease, entanglement, and disturbance. Once operational, it is expected to rehabilitate up to 30 seals annually, reducing the need to transport animals to distant sanctuaries. Beyond direct care, TSCT envisions the site as a hub for coastal conservation, hosting researchers, charities, and local groups. For the Tees region, this project represents a major step forward in strengthening the UK’s seal‑rescue network and connecting communities with marine conservation.  

Scottish Facilities

Several centres in Scotland, including the Scottish SPCA National Wildlife Rescue Centre, offer rehabilitation for seals from the northern coasts and the islands. Smaller groups such as Caithness Seal Rehab & Release support remote areas where strandings are common.


The Situation Today

The UK now has a mixed system: long-established sanctuaries with decades of expertise, supported by volunteer-driven organisations and emerging regional centres. Communication between groups is clearer than ever, with BDMLR acting as the national first-response coordinator and local teams providing on-the-ground knowledge.

Natureland in Skegness and the Cornish Seal Sanctuary continue to set the standard for rehabilitation work. Their histories have shaped the way the country approaches marine-mammal welfare, and they remain key destinations for pups that need long-term care.

This structure has created a strong foundation for understanding what happens after rehab as well. Tracking, post-release monitoring and long-term studies now offer insight into how rehabilitated seals behave once they return to the wild—topics explored further in the article that follows.
 

Where Do Rehabilitated Seals Go? Tracking the Journeys of Released Common and Grey Seals

When seal pups are rescued, rehabilitated, and released back into the wild, their journey doesn’t end at the shoreline. Thanks to satellite GPS tracking and long-term monitoring, researchers are now uncovering the remarkable dispersal patterns of these marine mammals — and the data tells a compelling story.

From Cornwall to France and Ireland: 100–200 Mile Journeys

Recent studies by the University of Exeter and the Cornish Seal Sanctuary have tracked rehabilitated seal pups traveling astonishing distances. One pup, nicknamed Maggot, swam 150 miles from Cornwall to Brittany, France. Another, Pink Heptahedron, made a similar journey to Wexford, Ireland. These aren’t isolated cases — tracking data from Cornwall Seal Group Research Trust and BDMLR confirms that dispersal of 100–200 miles is common.

Why Do They Travel So Far?

The primary driver is food. Released seals must locate productive foraging grounds, and juveniles often travel widely before settling into seasonal ranges. But dispersal isn’t just about hunger:

 Competition avoidance: Coastal areas near release sites may be crowded with wild seals, prompting juveniles to seek less contested waters.

Exploration and learning: Young seals are in a critical phase of habitat testing, learning where to haul out and hunt.

Environmental pressures: Pollution, disturbance, and climate shifts can push seals to find cleaner, safer habitats.

Innate behaviour: Even wild-born pups disperse after weaning, suggesting rehabbed seals are following natural instincts.

What This Means for Conservation

These journeys demonstrate that rehabilitated seals are capable of reintegrating into wild populations. Their ability to forage, explore, and adapt confirms the value of rehabilitation programs — not just for individual welfare, but for broader ecosystem resilience.

Visualizing the Data

Tracking maps show seals crossing the Celtic Sea, linking UK coastlines with Ireland and France. These movements highlight the transboundary nature of marine conservation and the importance of international collaboration.

Rehabilitated seals don’t just survive — they thrive, explore, and contribute to wild populations across vast distances. Their journeys are a testament to the success of evidence-based rehabilitation and the power of GPS tracking to illuminate marine life in motion.

References

Cornwall Seal Group Research Trust (2021) Post-release monitoring of rehabilitated grey seal pups. Cornwall Seal Group. Available at: https://www.cornwallsealgroup.co.uk (Accessed: 27 November 2025).

University of Exeter & Cornish Seal Sanctuary (2024) Tracking rehabilitated seal pups using satellite GPS. University of Exeter Marine Ecology Research Group. Available at: https://www.exeter.ac.uk/research/marine (Accessed: 27 November 2025).

Mammal Society (2022) Seal dispersal and survival post-rehabilitation. Mammal Society Reports. Available at: https://www.mammal.org.uk (Accessed: 27 November 2025).

UK Government (2023) Seal movement and dispersal patterns in UK waters. DEFRA Marine Wildlife Division. Available at: https://www.gov.uk/government/publications/seal-dispersal-report-2023 (Accessed: 27 November 2025).

British Divers Marine Life Rescue (BDMLR) (2022) Rehabilitation outcomes and tracking of released seals. BDMLR Annual Review. Available at: https://bdmlr.org.uk Accessed: 27 November 2025).