Achievements

SUCCESS ACHIEVED IN MASS SCALE SPAT PRODUCTION OF GREEN MUSSEL (Perna viridis) IN VISAKHAPATNAM HATCHERY OF CMFRI

 

Green mussel (Perna viridis) has been spawned and larvae reared successfully to settlement of spat at the Visakhapatnam hatchery of the VRC of CMFRI, Visakhapatnam. Large scale spat production of green mussel in the hatchery has been achieved for the first time in India.

Spawning of the green mussel P. viridis occured on 08th December 2024. 6.5 lakh larvae were reared in the hatchery. The 'D’ stage larvae were obtained within 20-24 h. Feeding was initiated with microalgae Isochrysis galbana. Umbo stage was reached on the 8th day. The eyespot stage was reached on the 16th day. Pediveliger stage was attained on the 19th day. Spat settlement began on the 21st day and continued up to the 30th day. The spat are being fed with Isochrysis galbana and Chaetoceros calcitrans. Over 2.0 lakh spat have been successfully settled in the hatchery. The spat are being reared in the hatchery. The technology can be further refined and will be ready for transfer to end users in due course. Large scale spat production in the hatchery has thus been achieved in the Marine Hatchery of the Visakhapatnam Regional Centre.

Broodstock Development, Induced Breeding and Larval Production of Cobia, Rachycentron canadum was achieved for the first time in India

At Mandapam Regional Centre of CMFRI, broodstock development of Cobia in sea cages was achieved by feeding with broodstock diets. The sexes were determined by cannulation and males and females were segregated and stocked in separate cages. The cannulations of the females were done at regular intervals to assess the size of the intra-ovarian eggs. On 11.03.2010, one of the female with intra-ovarian eggs around 700 μ was selected for induced breeding. The size of the female was 120 cm in total length and 23 kg in weight. Two males were also selected from the male cage. The sizes of the males were 100 cm and 103 cm in total length and weighed 11 kg and 13.5 kg, respectively. The selected brooders were introduced in a 100 ton roofed cement tank with about 60 ton of sea water on the same day. At around 1300 hours, the brooders were induced for spawning with HCG at doses of 500 IU per kg body weight for female and 250 IU per kg body weight for males. Spawning was noted at 0430 hours on 13.03.2010. The total eggs spawned were estimated as 2.1 million. About 90% fertilization was recorded (fertilized eggs amounted to 1.9 million). The eggs were collected by a 500 μ mesh and stocked in incubation tanks with varying densities. The eggs were hatched after 22 hours of incubation at a temperature range of 28-30º C. The percentage of hatching was 80 % and the total number of newly hatched larvae was estimated as 1.5 million. The newly hatched larvae measured in total length from 2.2-2.7 mm. The mouth opening was formed on 16.03.2010 (on 3rd day post hatch). The mouth opening of the newly hatched larvae measured around 200 μ. The larvae were stocked in 15 FRP tanks of 5 ton capacity each at an average density of 50,000 larvae per tank for intensive larviculture.The remaining larvae were stocked in three 100 ton cement tanks for extensive larviculture trials. The intensive larviculture tanks were provided with green water at a density of about 1x 105 cells per ml and rotifers enriched with DHA SELCO at a density of 6-8 nos. per ml. In the extensive larviculture tanks, green water along with rotifers are maintained. Good survival of larvae is being observed and the larviculture is progressing well.

Fishermen adopts small scale cage culture (CAPTURE BASED AQUACULTURE) at Uppunda, Byndoor, Karnataka: A success story

 

 Artisanal cages used for cage culture

Introduction:

The importance and popularity of farming food fishes is increasing rapidly in coastal States of India. Capture based aquaculture (CBA), wherein the juveniles of wild fishes caught are reared to marketable sizes in captivity, is being practiced throughout the world using marine and freshwater fish species of economic importance.

Background:

Estuarine and coastal waters of Karnataka is known for the abundance of finfish seeds of mullets, sand whiting, pearlspot, milkfish, Indian terapon, butterfish and flatfishes. During June- September, juveniles of a number of cultivable species of finfishes like Lutjanus spp. Gerres spp., Etroplusspp. are caught in the seines, castnets and gillnets operated along the coast. Usually these juveniles are discarded or are sold at a low price. An attempt was made to popularize the concept of capture based aquaculture by judiciously utilizing these seed resources.

Fishermen group:

The fishermen society ‘Sampradayaka Meenugara Sangha, Byndoor Valaya’ of Upunda village located at Byndoor participated with the researchers from CMFRI, Mangalore. It has been observed that, attitude change appears to be more readily achieved when individuals are in groups. Further, group decisions are more likely to be accepted by the individual farmer if he participates in the decision making process. Thus, group dynamics has been effectively utilized in the transfer of technology to the end users.

Capture Based Aquaculture:

Stocking: The concept of CBA was introduced in this village by collection of Lutjanus argentimaculatus, Etroplus suratensis and Lates calcarifer fingerlings and stocking in floating cages of 2.5 m x 2.5 m x 2 m, made of Netlon (mesh of 30 mm) lined with nylon net. It was envisaged to use local seeds for culture, in addition to assure good production seeds for Lates calcarifer was supplemented by CMFRI. The netlon cages was designed and fabricated by CMFRI with the participation of local fishermen. Five cages were provided to the fishermen for stocking the fingerlings.

Husbandry: The red snapper and pearlspot fingerlings were continuously stocked by fishermen and the fishermen community was engaged in the cage setting, cage cleaning, feed sourcing, feed preparation and feeding.  Feeding was done with locally available trash fish and also fish waste from fish processing areas/plants.  

Production and Harvest: Altogether five cages were installed and three of the cages were partially harvested as and when the fishes were grown to marketable  size, to meet day to day needs of the fishermen. Two cages were spared for final  harvest to demonstrate total production possible from these cages.

 Theses cages were harvested during July, 2024, when the mechanized fishing is banned. The Lutjanus sps attained an average weight of 755 ± 415g ranging from 105 to 1,914g. The pearlspot ranged from 37-222 g (96 ± 35g). About 255 numbers of seabass of average weight 1819 ± 540g was harvested. The total production from the cages including seabass, red snapper and pearlspot was around ~400 kg realizing a farm gateprice of ~Rs75,000 per cage.

 

Harvest details (2 cages)
Species	Mean size	Mean weight	Numbers	Harvest wt. (kg)	Amount (Rs.)
Redsnapper	350 ± 70 mm (190-500 mm)	755 ± 415g (105-1914g)	105	150	27,000
Pearlspot	158 ± 17 mm (115-205 mm)	96 ± 35g (37-222g)	988	150	22,500
Seabass	510 ± 50 mm (310-620 mm)	1819 ± 540g (262-3049g)	255	450	99,000
		Total	1348	750	1,48,500
Production per cage				375	74,250

 

Harvest in progress

 

Close view of harvested  Redsnapper ( Lutjanus argentimaculatus )

The fishermen view this as an alternative source of fish when adverse climatic conditions prevent them from venturing into the sea. This concept could be popularized along the coast of Karnataka and sustainable use of the finfish resources to augment the fish production could be done. Demonstration of this methodology encouraged the fishermen to install cages of similar type in the estuary and at present many cages stocked with fingerlings of L. argentimaculatus, E. suratensis and L. calcarifer are found in the village. Thus this concept of CBA was adopted by the fishermen and the diffusion of the technology in this village has been phenomenal. This is because, this technology has imbibed all the attributes of an innovation namely relative advantage, compatibility, simplicity, trialability and observability. The innovation-decision process has undergone the stages of knowledge, persuasion, decision, implementation and confirmation before reaching the final adoption stage. In the normal bell shaped adoption curve, the technology has been adopted by the first category of dopters namely the innovators. Similar cages are also installed in Kundapura estuary and the small size fishes which are otherwise discarded are grown into marketable size in these cages. This concept could be popularized along the coastal Karnataka and sustainable use of the finfish resources to augment the fish production could be done. The popularization and adoption of the concept of CBA by the fishermen would generate alternate livelihood, income and contribute to fish production of the region. The persistent efforts to bring forth a selective contact change on the part of the researchers and extension system of the centre is expected to bring about a major social change among the coastal fisher folk of this village.

 

Full view of harvested  Redsnapper ( Lutjanus argentimaculatus )

 

Mangalore RC of CMFRI