Though in Japan’s southernmost islands temperatures are already reaching into the 20s C, which many would call summer weather, in the north the temperatures have been fluttering and dipping, generally remaining well on the frigid side and with the definite feel of winter. In fact, some of the major lakes have only frozen in the last month, and with colder temperatures further north still, the drifting pack ice or sea-ice only reached the Okhotsk Coast of Hokkaido in early February, turning what was a leaden gray seascape brilliant white.
While the southern islands are already alive with the sounds of buzzing insects, in the north, the bizarre harmonics of frozen lake ice as it cracks, and the eerie creaking and groaning of sea-ice as it impacts on the shore are the distinctive seasonal sounds.
Accompanying the arrival of the sea-ice are the Steller’s sea lions (Eumetopia jubata) which migrate annually to reach waters around northern Japan. I have written of wolves recently, and there is a connection here, for Steller’s sea lions may well be regarded as wolves of the sea. They are hunters.
Their English name, sea lion, and their scientific name “jubata” come from the fact that the massive males sport long manes of dense fur around their necks. The males and females of these seals are very different, a distinction known as sexual dimorphism: The males reach lengths in excess of 3 meters and weights sometimes exceeding 1,000 kg. The females are much more slender, not quite reaching 3 meters and weighing only up to 350 kg.
Like so many of the creatures of the Pacific Rim, they were discovered and studied relatively recently. One of my heroes, the German surgeon and naturalist Georg Wilhelm Steller, first studied them while he was overwintering on Bering Island, where he was shipwrecked upon his return from explorations of the north Pacific with Vitus Bering in 1742.
In Steller’s day, these pale to mid-brown animals would have been abundant. They are powerful swimmers, and once were common around the Pacific Rim from Japan to California, where they lived off the abundant stocks of fish and cephalopods, with the occasional supplementary meal of seal. Now, however, their numbers are a mere fraction of what they once were and most surviving rookeries are in Alaska and in the central Aleutian Islands.
Each spring Steller’s sea lions visit the rocky coasts at these rookeries. The large bulls arrive on shore first and stake claims to patches of rocky shoreline. Each defends his patch with ritualized barks, bluffs, charges and occasional fighting to drive off their competitors. So obsessed are they in the hormone-driven spring battle to establish territories and attract a breeding harem that they may not eat for two months!
Among sea lions, size counts for a lot. The larger the males, the more likely they are to be able to maintain the defense of their beach territory and thereby be able to mate with the females that land on that strip of beach. The physical cost of battling on the beaches and then mating with up to 30 females is so great that most males lose their place in the rookery within a matter of three or four years.
The females, which are the cause of all the blustering and posturing among the males, arrive at the rookery after the males have already established their territories. In an incredible concentration of all of their essential land-based behavior in one brief season, the females who mated the previous year give birth to their pups within a few days of coming ashore, and then within the next two weeks they enter heat once more and mate with the bulls on shore.
The nearest rookeries to Japan are in the Kurile Islands and around Sakhalin. It is from there that the wintering animals, known here as todo, reach Japan. The existence of a Todo Cape in the Tohoku region of Honshu bears witness to their past presence at least that far south. Now they are to be found only around the coasts of Hokkaido, and most often along the east coast from the Shiretoko to the Nemuro peninsulas, though they are also found around Rebun and Rishiri, and as far south as Cape Erimo.
During the 1980s, in the heyday of the massive winter sea eagle gathering on the Shiretoko Peninsula, where the world’s largest concentration of Steller’s sea eagle could be found, sightings of Steller’s sea lions offshore were a regular bonus for early morning eagle watchers. The sea lions, particularly females, were to be found in groups and parties swimming off the river mouths along the peninsula, or patrolling the edges of the drifting sea ice.
With the significant decline by the early 1990s in the Rausu-based fishing industry, as a result of overfishing, the eagles have mostly dispersed. Eagle watchers now spend their time elsewhere, and the Steller’s sea lions must be having as hard a time as the human fishermen.
Before the 1950s todo appeared regularly around Hokkaido in winter. There they hunted fish, squid and octopus, in relatively shallow waters of 200 meters. They are able to dive to the bottom and resurface repeatedly with no ill effects, something impossible for human scuba divers to do.
As commercial fisheries expanded to include the same areas and the same species of marine life that the sea lions were hunting, conflicts arose. The animals were deemed the culprits for damaging the fishery of the lately arrived humans. It is not unlike a late arrival on a train punishing an earlier passenger for having already obtained a seat! Though the sea lions were there first, minding their own business long before humans even sailed the north Pacific, what they were doing was considered in direct conflict with human interests.
When fishing nets are set in the normal fishing grounds of the sea lions, it is inevitable that some will become entangled in them. Though risky, it is much easier for the lions to take their prey from the nets than to hunt the fish themselves. For this human-induced conflict, it is the sea lions that have been persecuted, with government support. The hunting of todo in Japanese waters has amounted to at least 22,481 animals between 1961 and 1992.
This has coincided with a drastic decline in the breeding population in the Kurile Islands from 20,000 to 4,000 animals over the same period. The likelihood that hunting in Japan, combined with innumerable deaths in trawl and drift nets, has caused this drastic decline in the population is overwhelming. Saddest of all is that recent research has concluded that the dramatic reduction of the sea lion’s numbers in order to “protect the fishery” hasn’t achieved any positive results for the fishing industry.
It seems that the sea lions have been killed in vain. The real reason for declining fish catches is, of course, grossly unsustainable overfishing, not the limited predation by a rapidly declining sea lion population. Sad to say, even the total elimination of the species would not solve the problems faced by the fishing industry, but in the meantime, pointing the finger of blame at the sea lions may enable fishermen to avoid thinking about the issue for a few more years.