Seaside “Sanctuaries” for Marine Mammals


Animal liberation activists want to shut down aquariums and marine parks. What would happen to the animals? For dolphins and whales, activists propose releasing them into coastal “sea pens,” which they call sanctuaries.

The Whale Sanctuary Project is raising money to build a sea pen on the coast of Nova Scotia. Additionally, activists made a sea pen off the coast of Iceland to house two beluga whales that were previously in a marine park.

While the idea may sound appealing at first, there are numerous challenges to the wellbeing of animals in seaside pens. The National Aquarium, based in Baltimore, announced plans to find a seaside sanctuary for eight dolphins by 2020–but as of 2023 still has not announced a site.

“[I]t’s not clear to me that it is any better than what the whales currently have,” says Andrew Trites, director of marine mammal research at the University of British Columbia’s Institute for the Oceans and Fisheries.

The Death of “Free Willy” 

Why can’t marine mammals in human care simply be released into the ocean? The release and death of the orca Keiko shows why.

Animal rights activists, spurred by the 1992 movie Free Willy, demanded the release of Keiko, the killer whale used in the film. Marine mammal experts who had more than a Hollywood education were skeptical. But more than $20 million was raised to release Keiko into the wild, and activists were determined to do it. The release effort was led by the Free Willy-Keiko Foundation and the Humane Society of the United States. (See Profile: Humane Society of the United States for more information on this group.)

Keiko was flown from the US to Europe, where the animal was first placed in a pen and eventually released into the open ocean. However, Keiko never joined a wild orca pod, and kept seeking human attention and feeding. He died, likely from pneumonia, in a cove in Norway in late 2003.

What is a Sea Pen? 

A sea pen is an area of coastline that is enclosed with a net. Some smaller fish and aquatic life would be able to pass through the holes in the net, but larger marine mammals would not. While larger than an aquarium, a sea pen would not provide access to an open body of water.

The Problems With Sea Pens

While the mental image of a sea “sanctuary” sounds pleasant, the reality is starkly different. Sea pens have a number of drawbacks from an animal welfare perspective:

  • Environmental contamination
  • Disease
  • Relocation stress
  • Reduced social interaction
  • Reduced care
  • Reduced lifespan

Environmental Contamination

In a facility such as an aquarium, water can be treated to ensure that it is of the highest quality for fish and marine mammals. This is not true for sea pens, which are in open waters and located next to a coastline.

Boat traffic can release oil and create noise pollution. Sewage, industrial and agricultural chemicals, and other runoff goes into the ocean. Trash and other litter goes from shore to water. Pollutants can create both sudden problems for animals in sea pens and also chronic problems as they bio-accumulate in the animal. This can lead to long-term health problems and death for marine mammals.


Just as the sea pen cannot stop pollutants from entering, it cannot stop zoonotic diseases from crossing its barrier, either. Because of the stress the animals would endure in being transported and placed into an unfamiliar enclosure, they would be more susceptible to disease.

Relocation Stress

Like pets, marine mammals in human care have become accustomed to their living environment. Moving them to a completely new environment will create stress for the animals. The transportation itself is stressful and complicated, and the new location will be unfamiliar to the animals.

“Moving them to a different environment could be very stressful to them and actually do greater harm,” says Andrew Trites, director of marine mammal research at the University of British Columbia’s Institute for the Oceans and Fisheries.

Reduced Social Interaction

Scientific research shows that dolphins benefit from contact with humans. Researchers have measured that stress hormones in dolphins are lower after they interact with people. In other words, dolphins don’t find swimming with people stressful–quite the opposite. Sea pens remove this social element from the animals’ lives; instead, they would only interact with other animals in the confined pen area.

Reduced Care

Just like people, dolphins can suffer from all kinds of maladies, including viral, bacterial, and fungal infections; cancer; heart disease; and respiratory problems. Under human care with dedicated staff, these conditions may be caught early and quickly. In sea pens, health problems will be harder to observe.

Reduced Lifespan

Dolphins in human care are given close care and attention, and it’s no surprise that they live nearly 30 years on average. A 2019 study found that dolphins in U.S. zoological facilities have lifespans that “are at least as high as those for the wild dolphin populations for which there are comparable data.” A 2014 review found that some facilities have average lifespans of almost 45 years for bottlenose dolphins, higher than the average lifespan in the wild of 25 years.

Given the above challenges, including less attention from human caretakers, it is unclear if dolphins in sea pens will live as long as dolphins living in human care.

Other Criticism 

The Whale Sanctuary Project’s proposed sea pen off the coast of Washington State drew criticism from a local Native American community. “Why does a whale sanctuary make sense? You can’t change nature that is wild,” said Judith Sayres, president of the Nuu-chah-nulth Tribal Council.

The Orca Conservancy also noted that moving marine mammals out of human care and into sanctuaries could be counterproductive. China is increasing the number of aquariums it has, and those animals can either come from animals in human care or their offspring, or taken from the wild. “By putting whales in sanctuaries, that would mean China will use wild captures to fill their aquariums rather than transferring in captive born whales.  The negative impact of wild captures far exceeds the negative impact of ongoing captivity for whales that have already acclimated to it,” the Orca Sanctuary writes.