University:
California State University, Northridge
Course:
BIOL 430/L | Ichthyology and Lab
Academic year:

2024
Views:

224

Pages:

2
Author:

Kolby Schultz

Grey Whale's Migration The gray whale is the only living member of the baleen whale family Eschrichtiidae. The gray whale differs from the other two baleen whale families primarily in its feeding behavior B it is a bottom feeder. Gray whales inhabit the eastern North Pacific Ocean. They spend summers in the icy waters of the Bering and Chukchi seas, off Alaska. As the ice pack advances in the fall, gray whales embark on one of the longest known migrations of any mammal. Hugging the North American coastline, the whales swim south more than 9,000 km (5,600 mi.) to Baja California, Mexico. The gray whale forages along the ocean floor. Turning on its side, the gray whale gulps great mouthfuls of silt, strains out water and mud through its baleen, and swallows bottom-dwelling invertebrates. Females give birth to 4.9 m (16 ft.) calves in the warm, shallow lagoons of Baja. While in the lagoons, some gray whales are unusually receptive to the attentions of humans who travel to the lagoons to see them. During the 19th and early 20th centuries, whalers hunted gray whales to the brink of extinction B twice. Legally protected since 1946, gray whales have made an astonishing comeback. The current population is about 21,000 individuals, a figure believed to match pre-whaling numbers. In 1993 the National Marine Fisheries Service (NMFS) determined that the gray whale should be removed from the Endangered Species List. Female gray whales average 14.1 m (46 ft.) and may weigh almost 32,000 kg (70,000 lb.) Male gray whales are generally smaller than females, averaging 13 m (43 ft.). Pollution May be Whale's Greatest Threat Pollution, not commercial whaling, constitutes today's greatest threat to whales worldwide, according to marine biologists from nearly 60 countries meeting here this week. More than 1000 experts in Monaco for the world's first Marine Mammal Science Conference said industrial fishing also posed a threat to marine mammals by infringing on their natural food supplies. But record levels of man-made marine pollution was threatening some species with extinction, they said. Whaling, once the prime threat to the world's largest mammals, is no longer a serious concern among scientists monitoring their numbers and well-being as long as the catch of minke whales remains at what the International Whaling Commission (IWC) says is a few hundred whales a year. ``That may be shocking because we're talking about whales, but whaling today is really not endangering any whale populations because the catch is relatively small,'' said Anne Collet, a marine biologist with the Marine Mammal Research Centre in La Rochelle, France. ``The real problem is pollution, particularly heavy metal pollution,'' said Collet, one of the organisers of the conference here. ``The problem is all the more serious and widespread because marine mammals are at the end of the food chain.'' ``We are not getting at the causes of pollution today,'' she said. Two things are clear, she said: pollution diminishes the immune systems of marine mammals, making them more prone to viral or bacterial attacks, and it reduces reproduction by preventing conception or provoking miscarriage. Under the combined pressure of pollution and whaling, some of the more fragile species are today on the brink of extinction, as is the case of the Mediterranean monk seal.