COLLECTION OF LIVE JUVENILE Siganus USING DIVERSE GEARS AT THOOTHUKUDI COAST

Siganus fishes which are commonly called as rabbit fishes or spine foot fishes are herbivorous fishes recorded in the nearshore waters.  They are normally distributed in the coral reefs, mangroves, seaweeds and sea grass beds. Due to their lower trophic level and carbon efficiently, these fishes are emerging as a candidate species for aquaculture.  

As hatchery technology is yet to be standardized at India, juveniles were collected from nearby shore.  The collection efficiency of three different gears at various nearshore environment were assessed.  Crab gillnet, gillnets and traps were operated at three nearshore environment of Thoothukudi Fig.1) usually during late evening and early morning. The number of fish caught by each gear was recorded. As per the gear the live and dead animals were analyzed and % live fishes caught by the gear was recorded. Effect of net soaking time, depth of collection, species, effect of aeration and water exchange on fish survival were analyzed.  The live fishes were taken to the SRFF facility with aeration and without aeration in a 30 lit plastic bucket.  A formalin dip as well as freshwater dip was given to disinfect the animals.  They were monitored for 21 days and based on the survival the best method for collecting the juveniles were assessed.

Among the various methods followed, the fishes collected on crab gill net survived better that other gears.  Survival of fishes collected onboard mainly depended on the following factors viz. time taken for collection, handling of live fishes by the crew, depth of collection, haul duration, type of fish (Species), density in the collection tank, water exchange rate and aeration rate.  

From the following it could be understand that among the various methods followed the fishes collected by crab gill net showed higher survival which consist of lower depth and less soaking time provided with sufficient aeration .