Breeding of grey Mullet pdf

Breeding of grey mullet

11.1. Distribution and importance

• Grey mullets belong to the family Mugilidae and Order Mugiliformes
• They are distributed in the Indo-Pacific region; commonly cultured in Indonesia, Philippines, Taiwan, etc.
• One of the most important groups of brackishwater fishes cultured
• Found in both the coasts of India, but is more abundant in the east coast
• Hardy, highly resistant to diseases, euryhaline, herbivorous and easy to culture.
• Widely cultured in South-east Asian countries in brackishwater and marine waters.
• Harvested from Indian estuaries and coastal waters.
• Form an important fish in pokkali fields of Kerala
• Good food fish.
• Mugil cephalus (striped grey-mullet) is the most important species and has good growth rate.
• M. cephalus grows to comparatively to a large size (400-500g in 6-8 months).
• Non-availability of seed is a major constraint.
  

Identifying characters

·                  M. cephalus has elongate and stout body, with emerginate caudal fin.

·                  Head moderate, concave between eyes.

·                  Mouth ventral, protrusible.

·                  First dorsal fin inserted nearer to caudal fin.

·                  Dull brown superiorly, lighter along abdomen; dorsal and anal fins stained with gray. Eyes golden.

11.2. Brood-stock development

• M. cephalus broodstock is raisedin rectangularcement tanks in the presence of benthic algae and plankton and artificial feed.
• Female brooders are selected based on ova-diameter.
• Females that possess eggs having a diameter of 600 µm or more are selected for injection.
• Gonadal development is synchronous and six stages gonadal maturity are found.
• Mature brooders of 4-6 years are preferred
• Does not spawn naturally in captivity.
• Spawns naturally in open sea during May-August.
• Difficult to identify ripe brooders based on morphological characters
• Fecundity : one million/kg b.w.

11.3. Induced spawning

• No. of injections – mostly two, interval between the two is 24 h
• Water quality requirements: Salinity – 32-38 ppt, temperature - 27-32⁰C
• After 2^nd injection, 2-3 males are released with one female
• Dry method of fertilization is practiced, if necessary.
• Spawning occurs 12-18 h after injection.
• Hatching period : 16-30 h.

Hormones and dosage are as follows

Hormone	Dosage
	Female	Male
Carp pituitary homogenate (CPH)	20 mg/kg	1/3 dose
HCG	5,000-10,000 IU/kg	1/3 dose
mLHRH-a	200-400 µg/kg	-
Synahorin (HCG + CPH)	10 – 60 Rabbit units	-

Larval rearing

• Larvae are small, ranging from 2.5 to 3.5 mm and tend to avoid direct sunlight.
• Hatchlings are fed with Artemia nauplii and zooplankton.
• The larvae grow to fry stage in about a month and are ready for transfer to freshwater nursery pond.