effect of packing density and habitat material on ... -
Proceedings ong>ofong> the Tenth Kerala Science Congress, January 1998, Kozhikode pp 251-25404-49EFFECT OF PACKING DENSITY AND HABITAT MATERIAL ON THE SURVIVAL ANDDURATION OF PENAEUS INDICUS POST LARVAE DURING OXYGEN-PACKEDTRANSPORTATIONCeetha Sasikumar ong>andong> Jayasree ~ idhyar KColleg ong>ofong> Fisheries, Keraia Agricultural University, Panangad, Cochin - 682 506.Absrmn: The survival ong>andong> duration ong>ofong> the Indian white shrimp. Penorw indieus postlarvae (PL,) packed with oxygen undnuniform water quality conditions wcrertvdisd atong>packingong>dcnriticsong>ofong>200.300,400 ong>andong> 500PLII. with ong>andong> without ong>habitatong> ong>materialong>wvJich was in the form afhailaw 10-15 mm bits ong>ofong> tranrlurccnt plastic *raw at a ratio ong>ofong> 1 bit: 2 PL. The ong>effectong> ong>ofong>ong>packingong> ong>densityong> onthe cumulative percentage survival was significant. The duration ong>ofong> obtaining IW%survivsl ;which was taken as the 'safe duratioinal'transpon' was significantly different at all the ong>packingong> densiticstricd. The ong>habitatong> ong>materialong> had signitient ong>effectong> on enhancing theduration ong>ofong>tranrpon at higher ong>packingong> dendties ong>ofong> 4W ong>andong> 500 PLlduring the later period ong>ofong> ong>packingong> I.=., at 70% survival. Theduration ong>ofong> 100% survival was not altered significantly with the introduction afthe ong>habitatong> ong>materialong>. The duration ong>ofong>transport wasinversely related lo the survival rates. The water quality paramctns - dissoivcd oxygen, ammoniaN, free carbon dioxide ong>andong> pH -were also studied with ong>andong> without the ong>habitatong> ong>materialong> at thedifferent ong>packingong> densities, initially ong>andong> finally at 70%survival, ong>andong> thechanges that took piece in the oxyeen-packed sxpcrimsntal jars were discussed.1. introductionThe shrimp post-larvae an cannibalistic in behaviourong>andong> hence on beingtransported under oxygen ong>packingong>, do notong>ofong>ten reach their destinations in totality, Cannibalistictendencies develoo due to insufficient smce . (Subrahmanvam. . - .1973). higher temperature (Shiguena, 1975) ong>andong> in associationwith moulting (Varghese el a/., 1975; Segal ong>andong> Roe, 1975;New ong>andong>,Singholka, 1985; Subrahmanyam, 1986). Loweringong>ofong> temperature reduces the moulting frequency ong>andong> therebydiscourages cannibalism (Shigueno, 1975; Singhoika 1982).At normal temperature in the tropics, provision ong>ofong> ong>habitatong>ong>materialong> in the oxygen tilled transportingcontainers was foundto reduce cannibalism in the - eiant freash water . Drawn. .Macrobrachiurn rosenbergii post-larvae since it serves as a .shelter forthe over-stressed weaklings ong>andong> the newly moultedones which arevulnerabie topredation (Aliasong>andong> Siraj, 1988;Javasree - Vadhvar era[.. . 1992). . The aresent . studvwas aimedat determining the ong>effectong> ong>ofong>ong>packingong> ong>densityong> ong>andong> hollow ong>habitatong>ong>materialong> on the survival ong>andong> duration ong>ofong>oxygen-packed seedong>ofong> Penaeus indicus during transportation.2. Materials ong>andong> Methods'Hatchery reared P. indicus post-larvae (PLJong>ofong>aver-age weight 10 mg were used for the exprriinent. They weremaintained initially in I ton capacity rectangular fibre glasstank after acclimating them from 32 ppt to 25 ppt salinity ong>ofong>the tank water at ambient temperature ong>ofong> 3M1°C. They werefed ad libirum using powdered dry clam ong>andong> minced prawnmeat. Aeration wasprovided in ihe tank. g e feed remnantsong>andong> excaory wastes were removed tiom thetank by siphoning,once daily. Twenty four hours prior to the starting ong>ofong> thcexperiment, feeding was stopped. 'Transparent rigid plastic, air tight jars ong>ofong> 600 mlcapacity were used for ong>packingong> the shrimp seed underuniform oxygen pressure, water quality ong>andong> quantity.The screw type lid ong>ofong> each jar was provided with a onewayvalve for regulating the flow ong>ofong> oxygen as well asfor fecilitating the reading ong>ofong> oxygen pressure in theexperimental jars on a pre~sure gauge. Rourdon typepressure gauge w:th a precision ong>ofong> 0.02 Kglcm', tined hilh abressure resistant hose, regulating knob aid pressing nippleserved to fill in the oxygen in the experimental jars from anoxygen cylinder.Thisfecilitated wntirmationong>ofong> uniform initialoxygen pressure within the jars (see Jayasree-Vadhyar el ai.,1992).