Packing and transportation of fish seed

·        Packing and transportation of fish seed

 

·        Transportation of fish seed

·        Transportation of fish seed is gaining increased importance due to the ever increasing world live fish trade.

·        Successful transportation of quality fish seed from the site of production to the place of culture is an important factor which influences the viability of aquaculture industry.

·        Traditional method of transporting fish seed in hundies (earthen or aluminium pots) results in heavy mortality of fish seed during transport.

·        The main reasons for the mortality during transportation are: 

·        (i) lack of oxygen, 

·        (ii) accumulation of metabolites like ammonia, CO₂, faeces, etc., 

·        (iii) hyperactivity, strain and exhaustion, 

·        (iv) diseases and parasites and 

·        (v) physical injury.

·        Now, with the innovative changes brought about in the system, necessitated by the technological breakthrough achieved in aquaculture, the fish seed and broodfish transportation has become fairly dependable and safe, though there is still ample scope for further refinement.

·        In general, the methods of seed transport can broadly be classified into two systems:

·        (i) Open system, where the seed is transported with or without aeration/oxygenation/water circulation and 

·        (ii) closed system in which the seed is transported in sealed air-tight carries with oxygen/aeration.

5.3.1. Open systems

• Till the late forties of this century, fish seed was mainly transported using the traditional methods.
• Under this method, before transporting to long distances, spawn and fry are conditioned in order to empty their digestive tract and condition them to subsist in a restricted area they are inevitably liable to be subjected to during transport.
• The most common method of conditioning is to store fry in a cloth hapa in ponds or in a still part of the river.
• The period of conditioning depends on the size and health of the spawn, fry and fingerlings.
• During conditioning and transportation, fry and fingerlings should not be handled with bare hands lest the slime and scales covering the body be removed and thereby render them vulnerable to fungal and bacterial infection.
• Traditional method of transporting fry and fingerlings in hundies is practiced in Bengal. A traditional hundi is an earthen vessel, but later aluminium hundies were introduced.
• Though the hundies are of variable size, they are generally of two types, the smaller one of 22cm mouth diameter and 23 l capacity carried as a head load and the other larger one of 23 cm diameter and 32 l capacity used for transport by rail or bicycle or as slings.
• The hundies are filled with water from the same source as the fry and they are stocked at 50,000 in the smaller and 75,000 in the larger ones.
• About 58g of fine silt is sprinkled over the water surface in the hundi.
• During transport the hundies are shaken periodically.
• Addition of silt during transport coagulates the suspended organic pollutant as well as keeps down the zone and extent of pollution.
• The use of pulverized earth, activated charcoal and `Amberlite’ tend to absorb carbon dioxide and ammonia from the medium, consequently increasing the survival of fry.
• Improved open metal containers have increasingly come into use and are known to have an edge over earthen hundies.
• These are round vessels with a wide mouth, which can be closed with perforated pressed in lids, the larger type being 53 cm diameter at the base, 20 cm at the mouth and 38 cm high.
• To prevent denting and effect of insulation, woolen covers are used on the metal containers or the vessel is aerated and kept wet during the journey.
• Transport of carp seed in Aluminium pots mounted on bicycle or tricycle is a common sight in Kolkata.
• Another container traditionally used for the transport of fish fry and fingerlings is galvanized round tin carriers with a flat bottom of about 40-50 l capacity.
• The inner lid is perforated and dish like and it serves well for aeration by cascading down the water splashed into it during transportation.
• In other parts of the country, open method of transportation of fish seed is going out of use mainly because it involves constant vigil and frequent renewal of water on long journeys.
• And also it is not economical to transport bigger fingerlings and adults in small packing units.

5.3.2. Closed system

• In the closed system, the source of oxygen is not air, but oxygen which is supplied with a cylinder, into an enclosed space above the water.
• Earlier, sealed metal containers were employed with oxygen successfully for transporting fish spawn and fry involving long duration.
• The containers are made of galvanized iron and measured 45.75cm x 35.36cm, with airtight openings at the top, one to let in oxygen and the other to let out the displaced water.
• In the early 1950s, CIFRI, Barrackpore introduced the 18 l kerosene tins filled with air-tight screw-capped lids for filling, provided with tubes for draining in oxygen from a cylinder and letting out displaced water.
• About 900-1000 fry (1-2 cm long) could be conveniently transported by air for over 20 hr.
• The specially designed Aluminium containers were found most efficient, but considering costs of different types of containers tested, they recommended the latex-rubber bags for commercial use.
• The Department of Fisheries, Maharashtra State gets the credit for introducing polythene bags for the successful transportation of major carp fry.
• The fry (20-25 mm) was transported in polythene bags (840mm x 610mm; thickness 0.0622 cm) inflated with oxygen, kept in kerosene oil tins (18 l), from Calcutta to Bombay.
• It was found that in such bags approximately double the quantity of fry than those transportable in hundies could be shipped.
• Singh (1977) proved that rohu fingerlings need greater quantity of oxygen for transport during the same period as compared to mrigal; the oxygen required for 50 fingerlings of rohu (109-126 mm) for transport during a 12-h period is 1,680 ml against only 475 ml for mrigal (98-100mm) at 31-32^oC.
• Singh et al. (1979) observed that oxygen requirement of silver carp fingerlings is higher than that of grass carp.
• In Karnataka State, carp seed are commonly transported by road in 18 l capacity high density polythene bag containing 1/3 water and 2/3 pure oxygen, sealed and packed in rectangular metal boxes (Basavaraja, 1994).
• The number of seed to be packed in each bag depends upon their size (from 2,000-10,000, 600-700 and 150-200 for spawn (<8mm), fry (8-40mm) and fingerlings (40-150mm), respectively.
• In Karnataka and Andhra Pradesh, fish farmers over the years, have developed a method of transporting fish fry and fingerlings in large (1000 l) sinter plastered tanks, with continuous oxygenation during the journey hours.