What happens to an 18-foot long, 2,000-pound body?
This question perplexed divers and photographers who frequently explore the waters off San Diego’s coast.
The saga began this spring when Doug Bonhouse took advantage of the mild weather to scuba dive at Scripps Canyon. As he submerged, a large mass caught his eye beneath him.
At just 115 feet below the surface, he discovered the body of a juvenile gray whale.
Whale carcasses are typically not encountered by human divers; they are usually found by remotely operated vehicles at depths exceeding 3,000 feet.
Local marine biologists speculated about the origins of the gray whale calf. The creature, which was suited to the seabed, had been sighted near La Jolla Shores, desperately searching for its mother. In its final moments, it appeared to approach a boat, as if pleading for assistance.
Other divers quickly made their way to the site, as it was the first opportunity for access during the autumn. Among them was underwater photojournalist Jules Jacobs, who documented his exploration for the New York Times.
By late January, the whale’s resting place was in a canyon valley that required careful navigation to reach. This challenge left Jacobs feeling both anxious and mentally drained.
As Jacobs navigated through the darkness with a team of five divers, the beam from his dive light suddenly illuminated the object of his search: a fragile calf with spotted skin. Its eyes had succumbed to the elements, frozen in an expression of sorrow.
“It’s humbling to swim through a whale’s carcass when only its tail is as large as your body,” Jacobs remarked.
Jacobs planned further dives to study the remains. On his second visit a week later, however, he discovered that the tail was missing, likely taken by scavenger sharks like Seven Gill and Mako.
After a series of spring storms, Jacobs descended again in late February. Gripping his camera gear so tightly that his knuckles turned white, he awaited the sight of the decaying creature.
He was met only by an empty seabed.
The calf was gone.
Adult gray whales can grow to about 45 feet and are known for their extraordinary migrations from the warm waters of Baja, California, to high-latitude feeding grounds in the Arctic Ocean. It’s likely that the calves and their mothers headed north before becoming separated. At this vulnerable point in their journey, the calves would have faced starvation after not eating for six months.
Gray whale populations experience cycles of boom and bust, recovering from significant declines, sometimes losing up to a quarter of their numbers within just a few years.
However, the population has failed to rebound for about six years, mirroring previous downturns. Scientists link this decline to climate change, which accelerates warming in the Arctic and disrupts the whales’ prey availability. Additionally, ship strikes and entanglements further exacerbate mortality rates.
“We are observing a significant increase in fatalities among gray whales,” stated Joshua Stewart, an assistant professor at the Marine Mammal Research Institute at Oregon State University. He anticipates more whale deaths along the West Coast.
Nevertheless, the death of a whale does not necessarily signify an end. Instead, it often triggers new beginnings.
Life flourishes from the remains of whales. Their meat nourishes scavengers, bones become habitats for microorganisms and insects, while the curved vertebrae provide a new foundation for flourishing coral reefs.
“Whale falls are ecological bonanzas, capable of providing sustenance for up to 200 years, as they typically reach the ocean floor,” remarked Craig Smith, professor emeritus of oceanography at the University of Hawaii. “Ironically, we understand more about deep-sea whale falls and associated communities than we do about shallow-water ecosystems.”
Whale decay occurs in three distinct ecological stages. Initially, scavengers like sharks, crabs, and hagfish consume the soft tissue. Next, worms thrive in the nutrient-rich, vibrant masses surrounding the carcass, as Dr. Smith notes; this phase can last up to seven years and is termed an enrichment stage by scientists.
Ultimately, bacteria deep within the bones produce hydrogen sulfide, fueling chemically-chemosynthetic bacteria that thrive symbiotically with the animal hosts and chemically synthesized bacteria on the bone’s surface. This final stage can endure for decades, supporting over 200 marine species within the ecosystem generated by a single whale fall.
However, the calf and its remains had vanished. Was something or someone responsible for preventing the whale fall that would support life?
Gregory Rouse, a marine biology professor at the Scripps Marine Research Institute, considers the matter less enigmatic. He explained that during the whale fall, decomposition within the body cavity can generate gas, causing the body to rise again after initially sinking.
It’s also plausible that strong winds and turbulent currents carried the body deep into the canyon. It could have descended to 1,600 feet below.
“The animal could have grown into a titan, but its life was cut short in infancy,” Jacobs reflected.
However, if it rests quietly in the depths, new life may proliferate and thrive.
Source: www.nytimes.com
