Increasingly sophisticated techniques since the late 20th century have led to the massive harvesting of sharks and rays. Previously invincible species such as mako and basking sharks are killed for their fins only; the remainder is thrown overboard. In parts of Asia, shark-fin soup is consumed as an aphrodisiac.
A worldwide movement aims to stop such wasteful practices and conserve some of the vulnerable larger sharks. The 2000 World Conservation Union Red List categorises 19 species as vulnerable, 17 as endangered, and four as critically endangered. Four New Zealand sharks – the basking, spiny dogfish, whale and great white – are listed as vulnerable.
In Australia, South Africa and parts of the United States, the great white is a protected species. The grey nurse shark is also protected in Australia. Great white sharks have been fully protected in New Zealand since April 2007.
Curtailing shark fishing
Formed in 1957, the New Zealand Big Game Fishing Council has 61 affiliated clubs with 33,000 anglers throughout the country. Many of these anglers catch sharks – the most sought after are mako because they fight fiercely and are good eating.
In recent years, however, there has been a change of approach. Rather than take sharks home, many anglers prefer to release them to fight another day. They will land a shark only if it could be of record-breaking size.
A cure for cancer?
Long believed to have health-giving properties, shark cartilage and liver oil are manufactured by several companies in New Zealand. There is a widespread belief that sharks do not get cancer or other diseases. However, no systematic research has been carried out to prove this.
In 2002, New Zealand researchers at Industrial Research Ltd and the Wellington School of Medicine tested the anti-cancer properties of shark muscle. Their studies showed that, when fed to rats with cancer, the extract prevented new blood vessels from forming. Because cancer spreads through the body through these vessels, shark muscle may help in the fight against cancer. However, the product does not actually stop cancers from forming; it may simply delay the progression of tumours.