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Humphead wrasse

populations and sizes

Research and education in biodiversity conservation and sustainable use of marine environments of East Malaysia.

 

HUMPHEAD WRASSE POPULATIONS IN SABAH

 

Humphead wrasse with large viable populations are currently only found around the coast of Sabah, Malaysia at Pulau Sipadan and Pulau Layang Layang.

Pulau Sipadan, situated on the East coast of East Malaysia (1 hour boat ride from Semporna), is amongst the top ten dive sites of the world. Destruction of its coral reefs was quickly stopped during the mid-1970's with the construction of dive resorts and the development of ecotourism upon its small shores. After more than 15 years of unofficial protection from resort managers Pulau Sipadan once again supports a vast diversity and abundance of coral reef fish as well as marine turtles with little to show for its past abuse. Pulau Layang Layang, situated some 300nm off the west coast of East Malaysia within the South China Sea, has evaded the attentions of fishermen due to its inaccessibility and protection from the Royal Malaysian Navy. Like Pulau Sipadan, fish diversity and abundance are very high, rivaling that of the Great Barrier Reef (Oakley et al, in prep), including a large viable population of humphead wrasse.

Estimated population size: 

Pulau Sipadan = 75 fish 

Pulau Layang Layang = 350 fish.

 

At each site, a 2 km x 20 m wide strip of reef ( along the reef slope) was searched, with divers at 15 m. 

Only 2 sites had more than 1 Humphead wrasse per kilometer. 

 

SIZE OF REMAINING FEW HUMPHEAD WRASSE

The species very poorly known so this study is asking simple questions about the biology of the species and the nature of the threats as a first step toward more informed management. The results of global reef check surveys show that the species has disappeared from even the best reefs over most of its range.  In Sabah, East Malaysia, surveys at 60 fished sites found only a few  immature fish yet at two reefs protected by ecotourism there were  viable breeding populations.

 

 

HUMPHEAD WRASSE ARE VERY RARE. THEY ARE LOCALLY EXTINCT OVER MUCH OF SABAH.

 

 

Pulau Layang Layang is almost unique in Sabah because it has a viable breeding population of over 350 individual fish (approx. 20/km of forereef).  Pulau Sipadan also has reproductive sized fish but the population is much smaller with approximately 70 adults.  There is a distinct shortage of small Humphead  wrasse on both these reefs.  Searches of all habitats on Pulau Layang Layang revealed only 3 medium sized fish (30-50 cm) and no small fish.  Recruitment is probably naturally variable on any oceanic atoll but with heavy fishing pressure on populations in adjacent areas the chance of recruitment is probably very small and restricted to the chance of larval fish being brought back to their natal reef.

Clearly, we have to manage these remnant populations of humphead wrasse carefully because even if the adults are protected the population is still very vulnerable to recruitment failure.

 

 

|HUMPHEAD WRASSE IN SABAH|  |HUMPHEAD WRASSE AND THE LIVE FISH TRADE|  |POPULATIONS AND SIZES|  |NATURAL IDENTIFICATION

|SOCIAL BEHAVIOUR|  |SPAWNING