WASHINGTON (CN) – The National Marine Fisheries Service has rejected a petition to list the eastern north Pacific gray whales as depleted, based on population levels of the species after decimation by the whaling industry, instead of historical population levels.
The California Gray Whale Coalition had argued in its petition for review that the species is depleted by historical standards, and the declining number requires the agency to prepare a conservation plan to restore the stock to its optimum sustainable population.
Gray whales were recognized as endangered even before the Endangered Species Act was passed, and were formally added to the List of Endangered and Threatened Wildlife and Plants in 1973.
In 1984 the agency determined that gray whales were no longer endangered, but the species remained on the list until 1994 when the agency determined that the population of the species was within 60 to 90 percent of the maximum population that its ecosystem could support.
The carrying capacity of the habitat for a particular species, given the needs of the rest of the ecosystem, is called “k” and the figure is at the center of the Coalition’s petition.
The petitioners say that the agency should have used the historical k–the capacity of the ecosystem to support a given population of whales when the species was at its maximum level of abundance before decimation by the whaling industry–as it has done in some status review and listing decisions, rather than on current estimates of k which are based on the way ecosystems are today.
While the agency has relied on historic levels of abundance to determine k for a few species, it has determined that in most cases it is impossible to determine the k prior to human exploitation and that its goal for conservation of a species is ‘equilibrium,’ thus, listing decisions must not be based on what ecosystems may have been able to support in the past.
The result, the Coalition argues, is that the gray whale can not reach its true optimum sustainable population because human activity will always reduce the k of an ecosystem through degradation and that ever smaller populations of the species will be accepted as the most that can be sustained.
The petition sites estimates placing the prewhaling population of gray whales at between 70,000 and 120,000 individuals and the agency estimates the current population to be about 20,000.
Mature gray whales can live to be 60 years old, reach 52 feet in length, and weigh up to 36 tons. Once found in both the Atlantic and Pacific Oceans, they are now known only as the relatively stable eastern north Pacific population and the endangered western, or Asian, Pacific population.