Many scuba divers feel strongly that killer whales should not be held in captivity, but new evidence of damage to orca teeth has reinforced calls to end the practice.
Orcas have some 48 large teeth, and a sore tooth is thought to be no less painful or debilitating in a killer whale than it is for a human.
The new research into 29 captive orcas held by a single company in US and Spanish facilities has found that tooth damage causes major problems for the animals from an early age.
“Every whale had some form of damage to its teeth,” said ex-orca trainer Dr John Jett, now a professor and first author of the paper, a collaboration between US and New Zealand-based scientists.
“We found that more than 65% possessed moderate-to-extreme tooth wear in their lower jaws, mostly as a result of chewing concrete and steel tank surfaces.”
The researchers also found that more than 61% of the orcas had “been to the dentist” to have their teeth drilled, with the soft tissue inside extracted in a procedure called a modified pulpotomy.
In humans the hole would be filled or capped but in orcas it is left open for the rest of their lives, and daily flushing with chemicals is then required to prevent infection.
“Teeth damage is the most tragic consequence of captivity, as it not only causes morbidity and mortality in captive orcas, but often leads to chronic antibiotic therapy compromising the whale’s immune system,” said co-author Dr Jeff Ventre, another former trainer who had drilled orca teeth in the past and witnessed whales “breaking their teeth on steel gates while jaw-popping”.
Most individual orcas could be identified by their tooth fractures and wear alone.
Ventre added that the daily teeth-flushing left the compromised orcas “poor candidates for full release”, should that possibility ever arise.
“We know that confining them in tanks is bad for the animals, and this research now gives us some hard numbers to illustrate just how their health and welfare is compromised,” said co-author Dr Ingrid Visser, an Orca Research Trust scientist who has studied orcas in the wild for more than three decades and advocates ending all orca captivity.
“Given how big the root of an orca’s tooth is and that orca have a nervous system similar to ours, these injuries must be extremely painful,” said Dr Visser.
“You just don’t see this type or level of damage in the wild.”
“Tooth Damage in Captive Orcas (Orcinus orca)” is published in the Archives of Oral Biology.
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16-Oct-17
