An abundant catch triggers curiosity

Several hundreds of balistids being loaded from a mechanised boat to a lorry at the Tuticorin fishing harbour.  

TIRUNELVELI, AUG. 21. A sudden excess catch of balistids (triggerfish) off the coasts of Tirunelveli and Tuticorin in the Gulf of Mannar this month has evoked interest among fishermen and scientists.

According to Venkataramani, Head and Professor, Department of Fisheries Biology, Fisheries College and Research Institute, Tuticorin, 36 species of balistids are known to occur only in the tropical seas across the globe. Of the 10 species found in the Gulf of Mannar, eight are recorded throughout the year. Among them Odonus niger, popularly known as `red-toothed triggerfish', is so common that over 1,200 tonnes of this variety is being harvested on the Tuticorin coast alone during the southwest monsoon period (June-September).

The profusion of balistids in the Gulf of Mannar during the monsoon could be attributed to seasonal currents and availability in abundance of their food organisms. This 7.50 to 31cm-long species has a life span of about six years. Odonus niger usually occurs at a depth of 5-40 metres and is abundant near coral reefs.

According to T. Vaitheeswaran, a scientist in the institute, this species mainly feeds on sponges, zooplankton and crustaceans and is caught mostly in trawl nets. It is identified by its blackish brown colour with a dark stripe running from the mouth to the pectoral fin base and its caudal fin is lunar shaped. Triggerfish have an aquarium value and are not preferred for human consumption. They are mostly sun-dried and used in poultry feed production. The triggerfish skin is leathery and thick, used in foreign countries to make belts and wallets.