Grey Whales of Baja California: ancient sailors of the Pacific

The gray whales making their annual migration trip to the coastal lagoons of Baja California make one of the most impressive journeys ever made in nature, covering up to 12,000 miles to and fro between the feeding grounds of the Arctic, as well as the Mexican breeding waters. These spectacular cetaceans, formally called Eschrichtius robustus, exhibit remarkable navigation as well as stamina and maternal affection that have amazed researchers and wildlife lovers over the years and is one of the conservation stories of the greatest success.

The eastern Pacific gray whales Baja population, which is estimated to be about 20,000-27,000, undertakes this great journey every year, due to the biological needs, which have influenced their habit over the millennium. This is due to their regular patterns and seashore path which makes them especially available to human observation and gives them a chance to study and connect with marine life in ways which most whale species cannot offer to the public.

Physical Characteristics and Adaptations.

Gray whales are 40-50 feet long and 30-40 tons when fully grown, being mottled gray in color, with much scarring and masses of barnacles on their bodies, giving each whale an individual appearance. Grays also have a full ecosystem on their skin unlike most other whales species, which have smooth skin, and have barnacles, whale lice and other organisms that create textured surfaces, a feature reminiscent of being encrusted.

Their filter-feeding strategies are possible due to their baleen plates (130-180 on a side of the upper jaw) that allow them to filter-feed unlike other cetaceans. Instead of getting the small planktons out of the surface waters, gray whales plunge deep in the sea bottoms rolling on their sides and sucking the sediment-harboring amphipods out of the mud. This scavenging habit leaves characteristic feeding scars on the seabed of the Arctic oceans, and provides the explanation of the asymmetry in the wear they generally show on their baleen.

The Migration Cycle

The southward movement starts in October when the ice cover of the arctic grows and the pregnant female will be the first to leave followed by other adults and the juveniles until December. The whales move about 75-100 miles per day, following the coastline where they make use of acoustic signals, topography of the seabed and perhaps detection of magnetic field.

When they arrive at the lagoons of Baja during the months of December to April, the whales birth, nurse and mate. Calves are 12-15 feet at birth and weigh about 1,500 pounds and grow rapidly on the milk of mother which is 53% fat--the richest of all mammals. During the weeks spent in shallow, sheltered waters, mothers build up strength in swimming and body fats required to get to the north.

The reverse migration begins in March and the newly pregnant females and males are the first to leave, then the mothers with calves who can delay as long as possible to develop their calves. By May, the bulk of the gray whales are back in nutrient-dense Arctic and subarctic waters where they forage hard over the summer seasons, increasing their energy stores of huge amounts of amphipods on which they survive through the winter migration and breeding season that follows.

Success and Continual Struggle of Conservation.

During commercial whaling, gray whales were almost eradicated, and by the beginning of the twentieth century, they numbered around a few thousand. It was only in 1946 that international protection was introduced which has enabled a remarkable recovery which shows that with proper protection and conservation of habitat, the population of marine mammals can recover.

Nonetheless, modern dangers such as vessel collisions, fishing equipment entanglement, noise in the ocean, and climate change effects to the feeding grounds of the Arctic demand further attention. The warmer oceans change the distributions of prey and sea ice which can cause a disruption in the fine-tuning that keeps such magnificent animals alive.

The gray whales of Baja California remind us that such conservation programs can be as spectacular as possible, and that it is possible that other endangered marine life will also be able to recover with equal success though their protection efforts and international collaboration. https://www.greywhale.com/grey-whale-watching-baja