Conundrum

At the same time hundreds of dead gray whales were washing up on beaches, their birthrate was plunging. Theories abound, but little hard data has been gathered to solve this environmental puzzle.

"I think with the government what happens is they respond to crisis," he says. "They don't get much money unless there's a crisis and the politicians lean on them and they produce a product."

So Le Boeuf, Bruce Mate from Oregon State University and several noted Mexican whale scientists decided to sidestep government red tape and collaborate on a paper. They had no intention of actually studying the feeding grounds or even applying for any grants.

"I think what you hope is that your paper presents an idea which stimulates further research," Le Boeuf says. "You don't necessarily have to do it yourself. You're moving things forward. I would hope that it would serve as a boot in the butt to the government."

Migrating whales captured by aerial photography.
Wayne Perryman
Migrating whales captured by aerial photography.

In fact, their paper has gotten wide circulation in the small world of whale research. The 12-page paper has been the catalyst for a growing debate on whether there are just too many gray whales for the environment to support.

The scientists relied on existing data of various kinds surrounding the 1999 strandings: the locations of the strandings, how often they occurred, the sex and age of the dead whales, their physical condition, reports of whales feeding in new spots, especially along the migration route.

They found that most of the dead whales were female adults, not the usual calves and yearlings. Tests of dead whale tissue samples, although limited, showed thin blubber and low levels of oil and fat, which suggested low energy reserves.

"If gray whales have become food-limited, a high stranding rate and lowered reproduction would be expected to continue until an equilibrium is reached," the scientists predicted.

Le Boeuf and his colleagues' "starvation hypothesis" held that whales were going hungry for two related reasons. One, changes in the northern ecosystem were reducing the whales' principal prey, the amphipods. Moreover, they theorized, there are simply too many whales competing for the same meal.

This "carrying capacity hypothesis" has floated to the top of scientific debate over the future of the gray whales. Some researchers think the population has grown so large that the ocean environment simply cannot sustain 26,000 or more grays. The large number of strandings was simply nature's way of cutting the herd down to a sustainable size, they believe.

Other scientists don't buy the carrying capacity theory. They think the strandings were a random event, a spike -- albeit a sharp one -- on the whales' biological timeline that shows an upturn in strandings every seven or eight years. The more likely culprit for the 1999 and 2000 strandings, they say, was a short-term warm water event, an El Niño effect that reduced the amphipods for a couple of years.

But some scientists like Le Boeuf and Mate, as well as many environmentalists, worry that the low birthrate on top of the high number of strandings means something more long-term is afoot.

"If the whales have come on hard times and their food supply is threatened, the first thing you would have is some starving in the first couple years," explains Le Boeuf. "So maybe that was kind of like the first cut and the weak ones have succumbed. So that perhaps explains why we have not had the same strandings rate."

Or perhaps not.

In July, two other leading gray whale scientists, Robert Brownell and David Weller, both on the staff of NMFS' Southwest Fisheries Science Center in La Jolla, California, submitted a paper to the IWC that argued against the carrying capacity theory. Both men have worked extensively with the Western Pacific gray whale population that is found mainly off Sakhalin Island in the Okhotsk Sea near Russia. That population has been deemed "critically endangered" and is down to fewer than 100 whales.

Brownell and Weller contend that by no stretch of the imagination could the Western gray whales be overgrazing their feeding grounds; there are simply too few of them. Yet they are dropping in numbers, too, almost to the point of extinction.

Instead, "more global or oceanwide changes may be influencing the availability of, or access to, primary prey for numerous large whale populations," Brownell and Weller say.

Again, Brownell and Weller don't have any recent data on the actual food supply. That's the work that won't be done until the coming year, perhaps by both NMFS and the National Science Foundation.

But the two scientists got together with 10 other whale experts at a meeting of the Society of Marine Mammalogy in Hawaii in December 1999. The group scrutinized photographs of skinny whales from both the Eastern and Western populations. Many of the features were the same: protruding shoulder blades, depressions behind the head and a pronounced ridge or visible "bulge" along the lateral flank.

The scientists concluded that the "starvation hypothesis" proposed by Le Boeuf earlier in the year was indeed plausible. "However, we do not think that starvation is necessarily related to exceeding carrying capacity."

Evidence from throughout the world points to something much bigger at work, they say. Skinny blue whales have been observed in the Gulf of California and skinny right whales have been spotted in the North Atlantic. Changing global weather patterns may be affecting sea ice, which means the feeding grounds are not as accessible to the whales. Plankton production may be off in the North Atlantic because of long-term weather changes.

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