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Monday, 3 March 2014

Questionable claims

Animal antics: Orcas during a show at SeaWorld in Orlando, Florida. They are a major draw at the park but marine scientists fear that when confined in tight spaces, the killer whales will have limited life spans. - MCT

Animal antics: Orcas during a show at SeaWorld in Orlando, Florida. They are a major draw at the park but marine scientists fear that when confined in tight spaces, the killer whales will have limited life spans. - MCT

The debate continues as to whether orcas live longer in the wild or in captivity.

IN the middle of Blackfish, the scathing documentary about SeaWorld’s killer whale programme, an activist says the whales in SeaWorld parks die early while their counterparts in the wild live as long as humans.

The claim, which goes unchallenged in the film, is a powerful contrast, meant to suggest that the giant marine mammals suffer when forced to live in man-made pools.

Yet SeaWorld Entertainment Inc says its killer whales have life spans equivalent to those of wild orcas, an assertion the company makes to show that it provides a healthful, stimulating environment for the 29 orcas it owns at four marine parks – the largest captive collection on the planet.

The truth is not nearly as simple as either side claims. The fact is that scientists don’t know for sure how long killer whales live. Some experts accuse both sides – the marine park industry, which is led by SeaWorld, and the anti-captivity movement, which Blackfish has come to symbolise – of cherry-picking research and manipulating statistics to support their arguments. That, they say, has muddied what should be an honest debate about whether the US should continue to allow killer whales to be exhibited in captivity.

“Both sides skew the numbers,” said John Hargrove, a former SeaWorld killer whale trainer who said he wants to see an end to captivity but who is also critical of what he calls the vocal “fringe” of animal rights groups. “This is a debate, but you have to debate with facts,” added Hargrove, who appears on screen in Blackfish.

One of the biggest obstacles to understanding the whales’ life spans is that researchers have studied only a small percentage of the world’s wild killer whales – a handful of populations off the coasts of Washington state, British Columbia and Alaska – long enough to reach trustworthy conclusions. Killer whales are found around the globe, from Iceland to Sri Lanka to Antarctica. There are at least nine genetically distinct “ecotypes”, according to Brad Hanson, a Seattle scientist with the US National Marine Fisheries Service.

Visitors watching orcas from the underwater viewing area at SeaWorld.
Visitors watching orcas from the underwater viewing area at SeaWorld.

It may be, for instance, that salmon-eating orcas in the Pacific Northwest have different life expectancies than mammal-eating orcas in the Southern Ocean. Several peer-reviewed studies conducted by US and Canadian government researchers have calculated average life expectancies for killer whales in the Pacific Northwest. The results range from 30 to 50 years for females – depending on which specific population was studied and during what period – and from 19 to 31 years for males.

Individual whales can live much longer. Maximum longevity has been estimated at up to 90 years for females and 70 years for males, depending on the study. Most of SeaWorld’s whales are far younger; only one has so far lived into her 40s.

But with the limited data available, scientists say it can be misleading to compare life expectancies between whales in the wild and those in captivity. Instead, they say, the more accurate comparison to use is the “annual survival rate” – essentially, an estimate of the percentage of whales in a population expected to survive each year.

One of the most recent studies of wild killer whales was led by Craig Matkin, executive director of the North Gulf Oceanic Society in Alaska. That survey found that a population of orcas off the southern Alaskan coast had annual survival rates generally of 97% to 99%, depending on their age.

The best known peer-reviewed study comparing annual survival rates between wild and captive killer whales was published in 1995 by a pair of fisheries service researchers. Using federal government records, they calculated an annual survival rate of a little more than 93% for captive orcas.

That’s a substantial difference. Put another way: captive whales were dying at a rate of more than 6% a year, close to three times the rate at which wild whales were dying. That study continues to be widely cited today by animal rights groups and other activists. It’s one of the studies the makers of Blackfish relied on while researching the film.

But newer studies suggest that captive whales are doing better. At a conference last month in New Zealand, a research team that included Douglas DeMaster – one of the co-authors of the 1995 study – gave a presentation indicating that the annual survival rate for captive whales had improved to about 98% in the past decade, based on data through November 2013.

The survival rate “for captive killer whales seems to be improving, although that is certainly not the only metric that we should be using in evaluating husbandry practices in captivity,” DeMaster said. He added that newer data indicate that captive-born whales, in particular, appear to be surviving at about the same rate as wild whales.

SeaWorld, for its part, says its whales have survived at an annual rate of about 98% during the past decade and about 97% during the past two decades. The annual survival rate for killer whales held at SeaWorld facilities since the 1960s is substantially lower, but the company says using the more recent data better reflects improvements in husbandry and veterinary care.

Of course, most of SeaWorld’s killer whales are younger and haven’t yet lived long enough to know for sure whether they will match the lives of whales in the wild. When the company says its whales have equal life spans, it’s actually making a projection on the basis of its annual survival rates during the past two decades, using an approach substantiated by researchers studying wild whales. – Orlando Sentinel/McClatchy Tribune Information Services

Tags / Keywords: Environment , Environment , ecowatch , orca , kille whale , captive animal , Sea World


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