For a bill looking to end the captivity of whales and dolphins in Canada, Thursday morning it’s sink or swim.

Senators on the upper chamber’s Standing Committee on Fisheries and Oceans will hear the amendments put forward by its sponsor, Independent Sen. Murray Sinclair, and are then scheduled to vote on it clause by clause.

They have been studying Bill S-203 since February. In that time there have been several moves afoot by Conservative senators to kill it quietly and avoid sending matters back to the Senate for a vote.

As Sinclair told iPolitics earlier this month, Tory senators have been very much in the corner with Marineland and the Vancouver Aquarium, which have helped them with their research and preparation.

“They haven’t been shy about it,” Sinclair said.

Marineland and the Vancouver Aquarium are the only two facilities in Canada that have whales and dolphins in captivity. Both want the bill killed and have lobbied hard to make that happen.

Last month Green Party Leader Elizabeth May filed a complaint with the federal lobbying watchdog related to efforts by Marineland and the Aquarium to thwart the bill. In her letter to Lobbying Commissioner Karen Shepherd, May raised concerns about possible past and ongoing breaches of the Lobbying Act.

Despite the complaint, over the weekend Conservative Sen. Don Plett tweeted about attending another event at the aquarium with his “friend” — Aquarium CEO John Nightingale.

Ahead of Thursday’s committee meeting, there’s been new research released by a group of scientists who’ve studied the teeth of captive orcas, including Dr. Ingrid Visser of the Orca Research Trust in New Zealand. She testified before the committee in June.

The researchers found that of the 29 captive orca studied in the United States and Spain, every one of them had damaged teeth.

Their paper, “Tooth damage in captive orcas”, was published in the latest issue of Archives of Oral Biology.

“We found that more than 65 per cent possessed moderate to extreme tooth wear in their lower jaws, mostly as a result of chewing concrete and steel tank surfaces,” said author Dr. John Jett, a former orca trainer and biology researcher at Florida’s Stetson University.

He said they’ve documented that this tooth damage starts at a very early age in captivity.

Fellow former trainer Dr. Jeffrey Ventre, now a medical doctor, said during his time at SeaWorld, he often saw whales breaking their teeth on steel gates in their tank, while jaw popping.

“Small tooth fragments were then collected below the gate while diving the pool.”

Researchers also found that more than 61 per cent of the orcas had been to the dentist to have their teeth drilled. That involves drilling a hole into a worn down tooth to extract the soft pulpy tissue that’s been exposed. That hole isn’t filled, as it would be in humans. It’s left open for the rest of the whale’s life and requires daily flushing with chemicals to ward off infection.

“A drilled tooth is severely weakened and if any other trauma occurs, fractures will happen. We have documented more than 60 per cent of the second and third teeth of the lower jaws were broken and this high number is likely linked to the drilling,” said Dr. Carolina Loch, who specializes in the dentition of whales and dolphins at the University of Otago in New Zealand.

Co-author Jordan Waltz said “the damage to the teeth of these animals is so severe that most individuals can be identified by the specific fractures and tooth wear alone, much like forensic pathologists use for identification of humans post-mortem.”

Visser said she’s not surprised by what her team found in its research.

“I have been to every facility in the world that has orca on public display and from the first time that I saw an orca in captivity in 1998, I was horrified at the damage to their teeth. I have been gathering photographs since then.”

That includes Kiska, the lone orca at Marineland, who was not a part of this study (all animals studied were all under the same care regime, as they’re owned by one U.S.-based company, which also owns a Spanish facility for “offshore breeding”).

Asked about the state of Kiska’s teeth, Visser has seen them multiple times and described them as “shocking.”

“There are also belugas at Marineland who have atrocious teeth,” she said. “Because the owner of Marineland doesn’t like what I have been exposing through my photographs, each time I have visited I have been removed from the facility before I was able to document all the belugas, but those that I observed had multiple issues.”

Given that orcas have a complex nervous system, which is extremely similar to humans, she said we can assume that they feel pain in similar ways, so it’s highly likely that all the orcas with extreme tooth damage have experienced severe tooth ache and pain.

“The two co-authors on the paper, who are ex-trainers, have described how the orca shudder and slink away during drilling processes,” Visser said. “I’ve personally observed an orca cringe during a daily flushing session. Those behaviours are clearly indicative that the animals are experiencing pain.”

She said the primary reason for orcas to chew on the tanks is oral stereotypies, which is an abnormal, repetitive behaviour that is performed for no outwardly apparent reason. They’re generally considered to be a sign of poor welfare conditions and as a way for the animals to cope with stress and boredom.

“Teeth damage is the most tragic consequence of captivity,” Ventre said. “It not only causes morbidity and mortality in captive orcas, but often leads to chronic antibiotic therapy compromising the whale’s immune system.”

Visser started studying orcas in the wild as part of her PhD work in 1992. Since then she’s studied them in Argentina, Antarctica, Australia, New Zealand, Papua New Guinea, Alaska, Washington State, and Russia. This chewing behaviour is not something she’s witnessed in the wild.

“I have never seen any form of stereotypies in wild orca and certainly not oral stereotypies. I have never read, in all the thousands of scientific studies I have gathered on wild orca, a single mention of stereotypies in wild orca,” she said.

“This is 100 per cent a result of keeping the animals in captivity. It is undisputed that an empty (tank) provides no relief from boredom, especially for an animal that is so highly evolved and intelligent.”

A Marineland spokesperson, who refused to allow his/her name to be used, disputed the study’s findings.

“Allegations of animal abuse and mistreatment related to Kiska or any other animal at Marineland are objectively false. All the allegations you repeat were made years ago and complaints registered to relevant authorities. All were thoroughly investigated and proven false,” the statement said.

“The allegations were made with malice with the intent to injure Marineland.”

Read the park’s response in its entirety here.