March 24, 2011

The Great Migration of the Grey Whales

It is the longest annual migration of any mammal in the world; and their destination is Mexico. Grey whales were recently on the brink of extinction, but this year up to 25,000 of them are expected to appear off the coast of Baja California. It is their mating season and, for a creature so big, that is quite a feat to accomplish.

Grey Whale

The grey whale (eschrichtius robustus) are giants of the sea. They can grow up to 16 meters (52 ft), weighing in at about 36 tonnes. However, those spotted so far this year, off the coast of Mexico, have been a mere 11 meters (36ft). As the name suggests, they tend to be slate-grey in color, with barnacles clinging to them for the ride through the ocean. They have two blow-holes, which cause a distinctive 'V' shape plume of water and air.

Their migration will have begun, in the icy north, last October. Starting in the Bering and Chukchi seas, they travel down the length of Alaska, Canada and the USA, in a journey of 6,000–22,000km (9,900–14,000 miles). By January, the first of them are spotted in Mexico, making for three of their favourite lagoons. Tens of thousands of them descend upon Laguna Ojo de Libre, San Ignacio and Magdalena, to birth their babies and breed some more.

The latter is a tricky process. The sheer size of the grey whales means that some co-operation is clearly required. The female will flip onto her back, stabilized by one or more males; her actual mate will then be able to approach. All of this beneath the watchful eyes and cooing of hordes of marine biologists and tourists gathered upon the shore. It is all clearly visible.

Grey Whale
Photo by Gerard Soury

Also very much in evidence are the female grey whales in labour and the newborn calves. The pregnant females are usually the first to arrive and the last to leave. Their calves are born tail first and already around 4.9 meters (16ft) long. They will stay close to their mothers, breaching the surface in a synchronized arc, not departing from the lagoons until late April or early May.

Like mothers everywhere, the grey whales wish to protect their babies for as long as they can. The lagoons of Baja California are too shallow for two of their greatest predators, orcas and sharks; while it is illegal for their third predator, humans, to hunt them here. Mexico is at the forefront of whale conservation, with many of its fishermen, in Baja California, trained and co-opted into protecting the grey whales during this season.

Grey Whale

Another huge danger lies out in the Pacific Ocean. This is pollution and littering. A recent study undertaken by researcher Rob Williams (University of British Colombia, in Canada) estimated that the migration route of the grey whales contains some 36,000 pieces of plastic and other human shed debris. The whales ingest large amounts of ocean water, as they swim, filtering out the smaller organisms from its stomach sacs. But anything bigger says put.

In April, last year, a dead grey whale was beached in Seattle. When its stomachs were opened, they were found to contain: more than 20 plastic bags, small towels, surgical gloves, sweat pants, plastic pieces, duct tape and a golf ball. (Vancouver Sun: Ocean garbage: Floating landmines)

Grey Whale

Grey whales came with a hair's breadth of extinction. A few years ago, the prognosis for their species looked very bleak. Their North Atlantic cousins disappeared completely under the harpoons of hunters, during the 18th century. The Pacific almost had a similar story. An infamous American whaler, Captain Charles Melville Scammon, discovered the Mexican grey whale breeding lagoons. Between 1857-1860, he hunted so many that the lagoons were nearly emptied. It has been a slow crawl back from the brink, but the outlook is good now.

Dr Jorge Urban, a grey whale expert based in Baja California, has already reported that this year's migration has brought nearly four times the usual number of grey whales. It appears that they are surviving out in the ocean's depths and that the future is looking rosy.

Grey Whale

For now, the tourists watch from the shores of the Baja; with experts on hand to explain to excited children all that they can see. Some go out on boats, but the fishermen are patrolling in vessels of their own. By Mexican law, none can interfere with the breeding and birthing of these majestic whales, and the fisherman are there to ensure that this is the case. They will let the tourist boats out only as long as they will not be disturbing the mating.

There will always be lone whales, just hanging out, awaiting their turn to breed or leave. Grey whales are some of the friendiest marine creatures. They are quite happy to swim alongside boats and, despite their checkered past with human beings, will pause to say hello.

AlJazeera currently has an eye-witness report and footage of the awe-inspiring scenes, in Baja California, right now: 'Breaking waves: The story of the grey whales'.

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