populations and sizes
HUMPHEAD WRASSE POPULATIONS IN SABAH
wrasse with large viable populations are currently only found around the
coast of Sabah, Malaysia at Pulau Sipadan and Pulau Layang Layang.
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.
|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|