Sex change & threatened species
The reasons for the fishes vulnerability to extinction are compounded in the case of groupers and wrasse by their sex change during growth. With severe fishing pressure foccused on the largest (male) fish, there are very few male fish surviving and therefore there is little chance of successful reproduction. It is little wonder that there is extreme concern that spawning aggregations are being selectively targeted by the live fish trade.
Within the huge areas that were surveyed by TRACC, the humphead wrasse and grouper species are also being heavily targeted at small sizes. Fish of below 40 cm are caught wherever they occur and transported to on-growing cage farms who buy the small fish and grow them to a preferred market size of 1-1.5kg. With heavy focused fishing pressure on both juveniles and adults, these fish could be the first marine fish to become extinct in the new millennium.
SPAWNING AGGREGATIONS, INDEED EVEN SPAWNING INDIVIDUALS, NO LONGER EXIST.
Barramundi cod (Cromileptes altivelis): The most prized and highly priced of all groupers in Chinese restaurants. They are further threatened by the large demand for juveniles by the ornamental fish trade. This fish was so rare that none were seen in our Sabah surveys. On the remote reefs we surveyed in Kalimantan, (see projects) there were Barramundi cod under almost every rock. One reef check survey saw 100 different fish in 100m of reef.
Humphead wrasse (Cheilinus undulatus): One of the largest reef fishes, and can weigh up to 200 lbs. Their longevity has never been accurately determined, although one humphead wrasse grew from a weight of a pound to about 70 1bs in 19 years. Much of the fish that are exported from Indonesia, Philippine or Malaysia are juveniles.
Click here for more details on declines in other species, e.g. Epinephelus lanceolatus (Giant or Goliath grouper), E. leopardus (Leopard grouper), E. aureolatus (Square-tailed coral trout).
Coral reef survey to 2005 menu
Survey sites – Ecotourism - Fisheries issues – Fisheries issues E Malaysia – Pelagic fisheries – Non reef fisheries
- Blast fishing – Frequency – Regulations – Economics – Effects of bombs on diversity – effects of bombs on reef structure
Cyanide fishing – Cyanide fishing Map -Regional threats – Market forces - Social impacts of cyanide – Environmental costs of Cyanide -
Reef fish population decline – Coral trout & Leopard Groupers – Large grouper size change with fishing - Sweetlips – Snappers – small groupers – Sex change & threatened species -
Humphead wrasse & Live fish trade -location map– Regionally extinct – HHW populations – Spawning & Feeding – ID of individuals
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