Science Articles

Big Fish, Little Sea

Wed, 5th Oct 2005

The Napoleon Wrasse

Helen Scales

Alongside their neighbours on coral reefs, few fish come close. They can even outsize turtles and sharks. With sad-looking lips and inquisitive eyes their faces are Napoleanwrassedecorated with intricate blue-green scribbles resembling New Zealand Maori war paint, hence their other name is Maori wrasse.

Napoleon wrasses are found on reefs across the Indian and Pacific Oceans and for my PhD I study them both on a pristine, remote atoll in the South China Sea and around the coral fringed coast of the northern Borneo.

Sadly it is becoming increasingly rare to catch a glimpse of the majestic Napoleon wrasse in the wild. You are more likely to see them swimming around tanks in expensive seafood restaurants in Hong Kong or Singapore.

Since the 1970's it has become a prestigious delicacy to dine on large, colourful coral reef fish that are killed moments before cooking. The Napoleon wrasse is an especially favoured status symbol. A plate of their rubbery lips sells for 250 US dollars and a magnificent 40 kilogram specimen can cost as much as 10,000 US dollars.

Despite the high value of these fish, and the growing demand, very little is known about Napoleon wrasses, their biology, how they are exploited, and how remaining populations might be protected from extinction. But what is clear is that this big fish is in big trouble.

Various features of the Napoleon wrasse biology make them especially vulnerable to overexploitation. Like many other large animals they grow slowly and take years to reach maturity, which means populations take a long time to recover from even low levels of hunting.

Their mating system also predisposes Napoleon wrasses to being heavily fished. During each new moon they congregate to mate at specific locations on the reef. Like lions in the African savannah, each group of Napoleon wrasses has a dominant male who does most of the mating. He stakes out his territory, fiercely chases off intruding males and mates with the dozens of females that arrive.

The timing of these spawning aggregations is highly predictable. In the population I study the females begin to arrive at 12.30pm, and everything is over by 3pm. The problem is that if fishermen learn the precise timing and location of these aggregations, then they too can lie in wait and catch many more fish than they would at other times by painstakingly hunting for these otherwise solitary fish.

The live reef fish market demands two distinct sizes of fish, both smaller "plate sized" individuals enough for a single diner, as well as outsized adults that will impress guests at a banquet. Plate or Banquet sized ? A Napoleon Wrasse - Click to enlargeEither way this spells bad news for the wild populations of Napoleon wrasses. The smaller fish are juveniles, taken from the wild before they have had a chance to reproduce. As for the large fish, these are all males and their removal potentially leads to a serious female bias. This is because Napoleon wrasses start off life as females and undergo a sex change when they grow to a large enough size, but this takes time.

It seems that Napoleon wrasses just aren't cut out for high levels of exploitation and my data are backing this up. I have collected thousands of records of Napoleon wrasse sales from fisheries in northern Borneo going back for nearly ten years. Graphs show that the number and size of Napoleon wrasses caught by each fisherman has taken an unmistakeable and disheartening nosedive over the years. This suggests that there are few Napoleon wrasses left and fishermen are struggling to find them.

The sales records also show another very worrying trend. As the Napoleon wrasse become a rarity their status and exclusivity escalate so that diners are prepared to pay even more inflated prices. As prices are driven higher, so is the incentive for fishermen to catch the last remaining fish.

What can be done to help? As with most fisheries, there is no easy answer. Just like the blue fin tuna or North Sea cod, there is too much demand for too few fish. If the trade were to be banned, fishermen would lose their jobs, but when the fish have gone there will be no trade and no jobs.

There is however a glimmer of hope for the Napoleon wrasse. Not all countries that could trade in live Napoleon wrasses actually do so. The trade is banned in the Seychelles and the Maldives and licences are strictly regulated in Fiji. These and other countries are beginning to realise that by leaving Napoleon wrasses on the reefs they can gain from scuba diving dollars.

The question is who is prepared to pay most in the long run, diners or divers?

Subscribe Free

Related Content

Not working please enable javascript
EPSRC
Powered by UKfast
STFC
Genetics Society
ipDTL