Coastal Aquaculture and Mariculture (2+1)

5.2.2. Fry collection and Hatchery production

Unit 5 - Finfish culture systems

5.2.2. Fry collection

• Most fry are obtained from natural systems.
• The striped mullet breeds in the sea, fry and fingerlings enter estuaries and congregate in shoals.
• The fry collection methods are similar to those of the milkfish. Commonly seines and dip nets are used.
• The most suitable areas for collection are marginal areas of rivers, tidal streams, creeks, swamps and inundated fields.
• They swim against slow currents and such areas are ideal sites for collection

Hatchery production

• Taiwan was the first to succeed in artificial propagation of stripped mullet.
• 2.5 to 3 years old spawners are obtained from the sea and stocked in cement tanks.
• They are injected with 3-5 mullet pituitary glands mixed with 20-50 rabbit units of synahorin (mixture of chorionic gonadotropin and mammalian hypophyseal extract) per female or with salmon gonadotropin.
• Eggs with best chances of fertilization are released 40-50 hours after hormone injection.
• A soft swollen belly with excretion of calcium deposits indicates they are ready to release eggs.
• Females are stripped and eggs are mixed with milt collected from males.
• Both dry and wet fertilization can be followed.
• 1.0 to 1.5 million eggs can be obtained per female.
• Eggs are incubated in flow through systems are in aquaria with static water and aeration.
• Eggs hatch in 34 to 48 hours at a temperature of 24^oC.
• Larvae are reared in indoor tanks.
• Newly hatched larvae are planktonic, they swim with heads down and bellies up.
• Larvae start feeding three days after hatching.
• They are fed fertilized oyster eggs.
• From 5th day onwards they are fed with rotifers and copepods. In 45 days fry are ready for stocking in grow-out ponds.