Sex change normality

Press, 22 July 1989, Page 22

Sex change normality

' NATIVES

By,

Andrew Jeffs

A change of sex is part of growing up for one remarkable fish, the spotted-black grouper, making all the large fish males. Upon reaching about one metre in length a spotted-black grouper will change from a female to a male.

These fish grow up to 1.5 metres in length and can weigh well beyond 45 kilograms. A fish of this size has been estimated to be more than 100 years old. The spotted-black grouper can also quickly change colour. Normally they are dark greenblack in colour with white-yellow spots. In a flash they can change gto a green-brown with pronounced pale stripes. They usually change colour when they are threatened or frightened.

In spite of their size and

appearance, spotted-black grouper are timid, but trusting and naive. For example, they will often nudge visiting divers inquisitively.

These fish live in shallow water on rocky reefs. They usually spend their days hiding out in large rocky crevices or in caves. They often share these with other reef fish or sometimes crayfish. The spotted-black grouper is a lurking predator, hunting for small fish and crabs.

This fish is found throughout the Pacific region, but in New Zealand waters is mainly con-

fined to the warmer waters of the most northern coast.

Very little is known about these unusual fish because in many parts of the world they have been wiped out by just limited fishing. Probably the only remaining unfished population of these creatures survive at the Kermadec Islands, the most northern point of New Zealand. This small group of Islands is some 1000 kilometres north-east of Auckland.

The isolation of these islands has discouraged fishing around them.