Born Free Foundation - Keep Wildlife in the Wild

Back to the Blue

Rehabilitation

Following Misha and Tom's rescue, they were subsequently moved to a specially designed, large 30m diameter, deep rehabilitation sea pen (more about the sea pen construction here) constructed by Born Free. 

Misha and Tom's rehabilitation pen © BFF

As with any responsible reintroduction of captive or semi-captive animals back into the wild there are certain criteria that need to be followed which reflect the best interests of the individual animals released, as well as the wild indigenous populations. This process must remain dynamic in order to adjust to the dolphins’ needs and any environmental variables but the basic principles are outlined below:

Full health assessment - ensuring that the animals are healthy enough for release and there is little or no chance of transmitting any known pathogen or disease to the wild dolphin population.

Returning Tom and Misha to their native waters and or within their home range - it is believed that both Tom and Misha were captured near Izmir.  Izmir is approximately 150 miles from where the animals are currently being held and well within their home range.

Gate preparation so they are primed to depart the pen at release – this has been established by encouraging Tom and Misha to move through an artificial gate into the medical pen.

Determining if the animals can effectively hear and echolocate – we are confident in their hearing abilities and monitor echolocation through the use of hydrophones.

Establish and document that the animals can readily kill and eat live fish – transferring the dolphins’ diet from frozen fish to live fish is a slow and calculated process but essential for successful rehabilitation. Their captive diet has consisted of hand fed fish for many years and we must convert that to live fish over the coming months utilising the following process:

  • Feeding the dolphins underwater allowing them to learn that their fish comes only from under the water’s surface, simulating how they encounter prey in the ocean.
  • Slowly introducing humanely stunned live fish to coincide with encouraging the dolphins to swim variably under the water.   (In their natural environment, dolphins randomly swim throughout the water column searching for food.)  Stunned fish are the halfway point between dead fish and live fish, so this works to transfer their focus to live fish.
  • Once the animals are variably swimming under the water and eating stunned fish, we can introduce live fish to them. It may take some time for them to start hunting live fish.
  • To help with this task, a technique called broadcast feeding will be introduced.  Broadcast feeds involve delivering a mixture of dead, stunned and live fish to the dolphins which will create confusion and initially disguise the introduction of live fish to their diet.  This will allow them to get used to the ‘feel’ of such a food source and will create competition between Tom and Misha, an essential survival technique for when they are in the wild.

Developing the animals’ strength and endurance – possibly the most important aspect of the dolphins’ rehabilitation.  In captivity, dolphins become dependent on humans and work very little for their food compared to being in the wild, subsequently developing behaviours such as lulling at the surface for prolonged periods. In the wild dolphins are constantly swimming, not only for food, but for predator avoidance, playing, or migration.  In captivity this behaviour is rendered useless and they tend to lose their physical stamina. Wild bottlenose dolphins swim at an average speed of 1.5-1.7 m/s with bursts of speed up to 8.3 m/s and frequently hold their breath for 20-40 seconds, and at times up to 6 minutes and more.

Like a human in physical training for competition, dolphins must be muscular and fit in order to handle many different situations from attacking a school of sardines to avoiding sharks. The better shape the dolphins are in, the more likely they are to survive in the wild.  Conditioning is undertaken with Misha and Tom in their sea pen by encouraging them to be constantly active, incorporating high energy actions such as bows (breaching the water), speed swims and more. As we consistently work with them on these activities they will become more fit and well-developed increasing their potential for success in the wild

Misha and Tom © Jeff Foster
Born Free Foundation
Broadlands Business Campus, Langhurstwood Road
, Horsham, RH12 4QP, UK - Charity Reg. No. 1070906


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