SECTION 3 Questions 28 — 40
Read the following passage and answer Questions 28 - 40
The Blue Whale
The blue whale is the largest animal in the world. A female blue whale weighing 150 tons (killed in the Antarctic in 1928) was the largest animal ever known to have lived during the Earth‘s 4600 million-year history.
The body statistics of a blue whale are amazing. Marine biologist, Ariadne Scott, describes them. “An average individual is 21 metres long and weighs 100 tons. It has almost 2,500 gallons of blood and burns up to 3 million calories a day. Its heart weighs more than a ton and the tongue alone weighs about 2 tons.” The life expectancy of the blue whale is harder to judge, although they are known to be among Earth's longest-lived animals. Scientist, Sophie Morton, explains how whale experts try and work out their age. “We have discovered that by counting the layers of a deceased whale's wax-like earplugs, we can get a close estimate of the animal‘s age. The oldest blue whale found using this method was determined to be around 110 years old and we estimate that average lifespan is estimated at around 80 to 90 years.”
Blue whales are also the loudest animals on Earth, with their calls reaching 188 decibels (a jet reaches 140 decibels). Recently, Australian marine scientists have detected individuals singing from almost 750 kilometres away. Although no one is certain, the blue whale calls are theorised to be probably a part of breeding behaviour. The Australian scientists can use the data they found for various uses. Australian Science Leader, Dr Mike Dance, said, “Using innovative advanced echosounders, we were able to track individual krill for the first time, allowing an examination of the changing internal structure of the krill swarms that blue whales prey upon. Our ability to find these blue whales also allowed us to investigate the whales' habitat.”
This enormous animal is a real gentle giant. The blue whale is a baleen, which means it feeds only on krill, a small shrimp-like crustacean. Its stomach can hold one ton of krill and it needs to eat about four tons of krill each day. The blue whale spends its summers following its prey and building up its fat reserves, but, as wildlife expert Jon Stephens explains, things change in winter. “Summers are spent in polar waters, because food production is higher there, but in winter, they migrate several thousand miles to warmer tropic and subtropic areas and fast for the duration of their stay while breeding, using the fat on their bodies to see them through the whole winter.” Blue whales usually only congregate for this reproduction and they do not live in the pods common for other whale species. They are found in small numbers throughout the world's oceans, except the Mediterranean and the Arctic.
Conservationist Patrick Liley explains why the blue whale fat is one factor that has threatened the blue whale. "Historically, hunters have chased them to harvest their meat and render the cold - resistant fat down to oil. The larger the whale, the more profit is made from a kill. Killing blue whales therefore made the most commercial sense." The blue whale is currently one of the world's most endangered whales. It was not hunted until modern techniques made them more easily attainable, but by the mid-1900’s, only about 1,000 were estimated to remain.
Blue whales have been protected from whaling since 1966 by the International Whaling Commission, though some were hunted unlawfully until 1972. Stocks in the Southern Hemisphere and North Pacific are currently recovering. The latest estimate revealed 15,000 blue whales remaining worldwide, while pre-whaling populations were estimated at perhaps 300,000 individuals. Although numbers are increasing, worries remain of the health of the population.
New Zealand fisheries spokesman, Alan Cook, explains. "It is not known whether the population is properly recovering. There is a real concern that the drastically depleted genetic pool created by the hunting will affect their capacity to breed properly. Only time will tell if the figures continue to grow."
Other threats to the blue whale include their involvement in other forms of fishing, climate change and destruction or modification of habitat. Fisheries Inspector, Steve Hartnett, describes the threat from fishing. "Like many marine animals, blue whales are at risk of ‘bycatch’, which is accidental entanglement in fishing gear, which can cause injury, infections, starvation and drowning." Climate change may also affect blue whales throughout the Southern Hemisphere by depleting or shifting the distribution of prey. Melting ice also allows oil companies better accessibility to oil and pas deposits. This can cause various problems for blue whales and their environment, including one that is not often considered. Alice Baggley, an environment spokesperson, explains the problem. "There is concern that noise pollution may affect blue whales’ ability to communicate, particularly in New Zealand, where there is persistent seismic activity for oil and gas extraction near a blue whale foraging ground."
The blue whale is the largest animal to have lived on the Earth. Like many creatures, human activities threaten its continued existence. Patrick Liley explains what he feels is the solution. "It's not a secret. Whaling caused the initial destruction of the blue whale, and it continues to do so. We need to make all countries stop whaling and close the loophole on ‘whaling for scientific purposes’ that permits commercial whaling to carry on."
