Growth and dispersal of razor clam Solen dactylus in the mudflats of Indus Delta, Sindh ‎Coast (Northern Arabian Sea)‎.

Abstract

The Razor clam Solen dactylus is being harvested for the last 10 years from mudflats in ‎creeks of district Thatta. The results of water and soil quality samples indicate the ‎suitability and support for growth, dispersal, production and reproduction of Solen ‎dactylus occurring in Indus delta eco-region. Water quality parameters of creeks ‎indicated the ranges of temperature of water and air 11 to 30 ℃ and 12 to 42℃, pH of ‎water between 8.2 to 8.9, alkalinity of water 267 to 480 mg/l, hardness of water 620 to ‎‎1150 mg/l, salinity of water from 22 to 33 ppt. The soil samples of mudflats indicated silt ‎clay 15 to 30%, sandy clay 20 to 40% and fine sand 30 to 40%. Spring, summer and ‎early winter seasons are suitable timing for harvesting razor clam. However, winter cold ‎and rainy seasons are not suitable for razor clam fishing. In winter, the animals become ‎inactive and remain in deep barrows and do not come to the surface. In period of rainfall ‎the razor clam holes were filled with fine silt thus large number of razor clam were ‎affected and even deaths may have been caused if mudflats were exposed at the time ‎of rain. ‎ The recorded mature size of razor clam ranged between length of 6 to 3.5 cm and weight ‎‎12 to 40 grams. A trained person dig-out 1.5 to 3 kg of razor clam in 12meter square in ‎‎20-40 minutes. Thus a person can exploit 10-20 kg of razor clam in a period of 3- 4 ‎hours, hence 15 - 20 kg of live razor clam can be harvested in a day or night by a person ‎when mudflat become exposed after tidal action. Coastal communities inhabiting creek ‎areas are engaged in its harvesting using traditional techniques of using salt and probing ‎with thin sticks and hauling razor clams from burrow during low tides when mudflats ‎become exposed. It is concluded that Razor clam is an ecologically important group of ‎marine organism, lives in mudflats and creek systems. Although the razor clams are not ‎locally consumed by native people of Pakistan but it is a fishery having export value ‎which foreign exchange earned by exporting it to South East Asian countries.‎