Monday, July 9, 2007

Shortened Lives in Captivity

Does captivity cause the premature death of cetaceans? This question has been debated for nearly as long as whales and dolphins have been on display. Marine parks and aquariums maintain that captive animals live just as long, if not longer, than animals in the wild.

Belugas and bottlenose dolphins can live up to 30 and 50 years, respectively while the latest estimates put the average life expectancy of wild orcas at 50 years for females and 29 years for males. The maximum life span for orcas is believed to be 60 years for males and between 80 and 90 years for females.

Of the 185 orcas held in captivity since 1961, only 26 have survived more than 20 years, and only two have survived for more than 35 years.

While comparative data between the longevity of wild and captive animals is limited, there have been some significant studies conducted showing captive animals live shorter lives than their wild counterparts.

For example, a 1997 study conducted by the International Marine Mammal Association (IMMA) compared survival rates of captive and free-ranging bottlenose dolphins, orcas and belugas. The information came from the United States Marine Mammal Inventory Report (MMIR) and data collected from studies conducted on free-ranging populations between 1973 and 1994.

Although the available data on free-ranging belugas was inadequate for comparison with captive animals, annual survival rates (ASRs) from both captive bottlenose dolphins and orcas were significantly lower than free-ranging animals.

These findings are disputed by an industry that continues to tell its visitors that bottlenose dolphins only live 30 years, an industry that has failed to improve survival rates for captive dolphins, even though this species has been kept in captivity for over 70 years.

Marine parks also underestimate orca longevity, claiming the average life span of orcas to be between 20 and 35 years. However, a 1994 study by the Center for Whale Research found that almost 65% of the 94-plus orcas in Washington waters were over 45 years of age. Field researchers in the Pacific Northwest also found, after more than two decades of studies that not one female between the ages of 12 and 25 had died.

Birth Rates

When a whale or dolphin is born in captivity, it is used by the industry as proof that the animals are happy and healthy. Most animals however, even those kept in less-than-satisfactory conditions, will breed if they are given the chance. The problem with captive-born animals is that they don’t live very long in captivity.

Birth rates for captive-born orcas, after more than 40 years in captivity, have been at best, no better than in the wild and have almost certainly been worse. Of the 185 orcas in captivity and 74 known pregnancies, only 33 calves have survived past the first year.

Captive-born dolphins are no better off, even though this species has been kept in captivity even longer, approximately 70 years. Still, the captive display industry continues to state that high numbers of infant mortalities are normal, as they also occur in the wild.

This position however, contradicts the industry’s argument that the animals are better off in captivity, protected from the dangers of an otherwise harsh environment.

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