SEED PRODUCTION OF COBIA

Radhakrishnan NairMFK1508

HISTORICAL BACKGROUND• Aquaculture research with cobia was first reported in 1975 with the

collection of wild caught cobia eggs off the coast of North Carolina.• By 1997 the technology to raise large quantities of cobia fry had been

developed. • In the USA, the first reported captive spawning of cobia occurred in 1996

in Mississippi. • Research on cobia was also conducted in early 1990s in Taiwan Province

of China and the technology to raise large quantities of cobia, fry was developed in 1997.• Between 2000 and 2006, aquaculture facilities in Virginia, Texas, South

Carolina and Florida also reported spawning cobia by either capturing gravid females, administering hormone injection or implants, or using photoperiod/water temperature manipulations to induce spawning.

RECENT ADVANCES IN INDIA • Realising the immense aquaculture potential of Cobia in India ,

the Central Marine Fisheries Research Institute (CMFRI) has been pursuing the broodstock development & seed production of Cobia.• At Mandapam regional Centre of CMFRI, success broodstock

development of Cobia had achieved on Wednesday, June 16, 2010.

DISTRIBUTION AND HABITAT

• Cobia are pelagic and are normally solitary except for annual spawning aggregations; • They will congregate at reefs, wrecks, harbours, buoys

and other structural oases. • They may also enter estuaries and mangroves in

search of prey.• They are found in warm-temperate to tropical waters

of the West and East Atlantic, throughout the Caribbean and in the Indo-Pacific of India , Australia and Japan.

DISTRIBUTION PATTERN

BIOLOGY• They are able to tolerate a wide range of temperatures

(eurythermal) and salinity (euryhaline) between 1.6 and 32.2°C and 5-44.5 ppt in the environment.• Cobia prefer warm water (>20 ºC) and typically have annual

migratory patterns. • Spawn many times from April to September, with peak in July.• Sexual maturity -in males at 1-2 years and in females at 2-3 years• Females grow larger and faster with maximum sizes up to 60 kg.• Spawning occurs in both nearshore and offshore waters where

females release thousand to million eggs (1.4 mm diameter) which are then fertilized by the males.

• The viable eggs begin development, are heavily pigmented, buoyant, and hatch in approximately 24 hours. • Cobia larvae grow rapidly and are large in comparison to most marine

species • Juvenile fish are found in both nearshore and offshore waters, often

among weedlines where they seek shelter from predators and can feed.• Cobia are opportunistic feeders and examinations of stomach contents

have revealed various fish, shrimp, squid, and, in particular, crabs.

SEXUAL DIMORPHISM

• No pronounced sexual dimorphism. • Sexual maturity is reported in males at 1-2 years and in females 2-3

years, with females growing larger and faster with maximum size upto 60 kg (Shaffer and Nakamura, 1989).

PRODUCTION CYCLE

STAGES OF COBIA CULTURE

Brood stock

rearing

Spawning & egg

collection

Hatchery productio

n

Nursery rearing Grow out

BROOD STOCK MANAGEMENT • Broodstock management usually includes collection, selection and

domestication of brooders as well as control of maturation, spawning and egg collection.• Broodstock development is mostly practised in sea cages in order to

ensure good water exchange and healthy environment. Brood fishes can be stocked at a density of about 2 kg/m3.• Trash fishes (sardines, scads etc.) are fed once in a day at the rate of 5% of

biomass or till satiation. The trash fish has to be supplemented with vitamins and HUFA (fish oil, squid liver oil). Broodstock nutrition is very important and there is positive correlation between HUFA in the broodstock diets and in the eggs and larvae.

• Bigger fishes of 10-15 kg weight having normal shape without any deformity and with healthy behaviour are selected as broodstock. The other important criteria for broodstock include bright colour and with anus easily recognizable.• Best temperature for maturation is around 27 ºC and the best salinity

range is 30-34 ppt.• Separation of males and females from the broodstock cage is required

for conditioning the fish for breeding• Cannulation can be done to assess the maturity condition of the female.

The maturation characteristics of female include egg with size above 0.7 mm, non-adhesive, white colour and round shape. • In the case of mature males, by gently pressing the belly, the milt oozes

out

• Usually two males and one female are introduced to the spawning tank. Natural spawning also can be obtained if brooders are selected properly.• Induction of spawning can be done by injecting LHRHa 20 μg kg-1 for

females and 10 μg kg-1 for males. • Spawning occurs within 12-24 h after the injection. • Egg collection can be done manually from the tank by employing 500

μm net.

Broodstock development and captive breeding at Mandapam

• The wild collected cobia brood fishes (hooks and line commercial catches)• In hatchery the fishes were treated with 100 ppm formalin (2-5 min)• Conditioned for 2-3 days in 10 t FRP tanks before transferring to cages.• These fishes were fed twice daily (@5% of bw) with sardines and other fish

species like Pellona and Ilisha and occasionally with squids and portunid crabs.• Vitamin and mineral supplements were also given twice a week along with the

feed.• The sexes were separated by cannulation using a flexible catheter (2 mm inner

diameter) and stocked in separate cages. • Thereafter, the females were cannulated every fortnight to assess the

diameter of the intra-ovarian eggs.

Induced Spawning• Spawning can be obtained either naturally or by inducing with

hormone• 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.• The spawning occured within 36 hours after injection.• The number of eggs spawned by cobia ranges from 0.4 to 2.5 million• Egg collection can be done manually by employing 500 micron net.

• The fertilized eggs were incubated in 2 tonne capacity rectangular / circular tanks (SD 200 to 500 eggs per litre)• The eggs were hatched after 22 h of incubation at a temperature

range of 28-30 ºC. • The percentage of hatching was 80%• The newly hatched larvae measured 2.2-2.7 mm in total length

LARVICULTURE AND SEED PRODUCTION

• Cobia eggs are pelagic with single oil globule which is resorbed completely at 7 dph• Larval mouth opens at 2-3 dph (temperature dependent).• Metamorphosis starts from 9-11 dph.

Stage of Larvae(dph)

3 dhp – 10 dhp • The enriched rotifer (Brachionus rotundiformis) @ 10-12 nos./ml, four times a day

• Rotifers enriched with DHA SELCO at a density of 6-8 nos./ml8 dhp - 10 dph • enriched Artemia nauplii @ 1-3 nos./ ml, 4-6 times per day.

10 dph – 18 dph • During the rotifer and Artemia feeding stage, green water technique is used in the larviculture system with the microalgae Nanochloropsis oculata at a cell density of 1x105 cells/ml.

18 dph – 25 dph • Weaning to artificial larval diets. While weaning, formulated feed has to be fed 30 min before feeding with live feeds.

• Continuous water exchange is required during weaning.

25 dph -40 dph • the larvae are highly cannibalistic and hence size-grading is undertaken every four days to one week.

• fry could be weaned totally to artificial diets

feeds was also started as per details given below:

• The juveniles measuring 10 cm (30 dph) length were ready for stocking in hapas • All the fingerlings of 10 cm length and above were stocked in hapas in

the sea for nursery rearing for about a month before transferring them to the grow-out cages.

NURSERY REARING

FIRST PHASE• 0.2 - 2g to 5g fry grow rapidly to fingerlings• Size 8-10 cm (20 to 45 dph)

SECOND PHASE• 2 -5 to 30 g (45 to 75 dph)• In large ponds with green water or in hapas in the sea.• Artificial feed are provided manually to satiation, 5 to 6 times daily.• grading should be undertaken

THE THIRD PHASE• 30 to 600 - 1000 g (75-150 dph to 180 dph).• Grading is undertaken only once during this stage

Nursery rearing of cobia generally comprises three phases.

GROW-OUT FARMING

• Cobia is cultured in offshore grow-out cages until they reach marketable size. Culture period ranges between 6-8 months. • Small scale family owned cage farms and commercial cage farms are

employed for cobia grow-out farming. Usually most of the cagefarms integrate nursery and grow-out culture in one area for convenient transfer of fish stock from nursery to grow-out cages. • Sinking and floating pellet feeds are used in grow-out cages.

SEA CAGES.

Norwegian type sea cage. Taiwanese type sea cage.

ENVIRONMENTAL FACTORS DO - >5mg/l, NH3 - <0.1mg/l, pH - 7.8-8.4, Salinity - 25-35ppt, Temperature - 24-330C

NUTRITIONAL ASPECTS

JUVENILESProtein 45%Lipid 5-10%Vitamin& minerals No information

Asian seabass or grouper feeds are accepted

FCR 1.5-1.8

DISEASES AND CONTROL MEASURESDISEASE AGENT TYPE SYNDROME MEASURES

Marine velvet disease;

AmyloodiniosisAmyloodinium

ocellatumParasitic

dinoflagellate

Coughing; flashing; operculum flared out;

reluctance to feed; visible on gills & fins; appears as small dark spots on gill filaments under a stereoscope

Copper sulphate pentahydrate; decrease salinity in some cases (freshwater dip); flush

system; formalin bath/treatment;

mechanical filtration down to at least 40

microns

Cryptocaryonosis; marine white spot

Cryptocaryon irritans External protozoan

White foci visible on skin; interconnected,

larger masses of whitish spots

Prolonged copper immersion; freshwater

dips; formalin treatment; decrease salinity to 15 ‰

or less for 2 weeks; decrease system

temperature to <19 ºC

Sessile, colonial, ciliate infestation Epistylis spp. Stalked ciliate

Reported during larval stage; white or reddish masses on the skin/fins,

gill arches, or in mouth; more common in polluted waters; often

associated with gram-negative bacterial condition called red sore

disease

Formalin treatment; freshwater bath/dip; antibiotics for severe

bacterial infection

Trichodinosis Trichodina sp. Protozoan parasite

Reported during nursery stage; found on skin & gills; loss of

appetite; lethargy; chronic low level mortality; often leads to secondary

infections

Formalin treatment; freshwater bath;

copper treatment; Praziquantel bath or

prolonged immersion

Monogenean infestation

Neobenedenia sp.

Monogenean flatworm parasite

Reported during grow-out stage; skin damage & ulceration; eroded fins; eye lesions which can lead to

blindness

Formalin treatment; freshwater bath;

copper treatment; Praziquantel bath or

prolonged immersion

Myxidiosis Sphaerospora-like myxosporidean

Myxosporidian parasite

Poor appetite & ascites; enlarged kidney exhibiting

patches or nodules; skin ulcers; spores in

the digestive tract

No known treatment; disinfect system;

quarantine affected fish

Coccidiosis Coccidia spp. Protozoan parasiteAbdominal swelling;

exopthalamy; cysts in liver tissue; varies with

organ affected

Treat fish with oral monensin; reduce

stress

Lymphocystis Iridovirus VirusReported during

nursery stage; skin, fins & gills with white,

bumpy growths

No known treatment; disinfect system; quarantine fish

PasteurellosisPhotobacterium damsela subsp.

PiscicidaBacterium

Whitish, granulomatous

deposits on kidney, liver & spleen

None known but vaccine being

developed

VibriosisVibrio alginolyticus; V.

vulnificus & V. parahaemolyticus

Bacteria

Swollen abdomen; skin ulcers; protruded

eyes; lethargy; darkening of skin;

ascites in peritoneal cavity

Administer antibiotics; remove diseased fish;

disinfect system; reduce stress

Secondary bacterial infection (after Neobenedenia

infestation)Streptococcus sp. Bacterium

Can cause blindness in cobia; protruded eyes;

skin ulcers; skin darkening

Administer antibiotics; remove diseased fish;

disinfect system; reduce stress

Recent success in Mandapam Regional Centre of CMFRI

Volitional spawning of cobia in RCC tanks– spawned volitionally without any hormonal induction during the

month of May 2013. – The water quality parameters were maintained at highest standards

with indigenously designed filtration systems.– A total of 2.5 million fertilized eggs were obtained and 85 % hatching

was achieved in the volitional spawning.

First successful spawning of cobia in RAS– Was achieved at Mandapam on 20th September 2013.– The total number of eggs spawned was 2.40 million and the

fertilization percentage was 86.1. – The temperature range was 27.5 – 29°C

The first successful off-season spawning of cobia– through thermal regulation has been achieved in the RAS on 02nd

December 2013.– Temperature was raised in the RAS to 29.7 to 30.3 °C, by titanium

heaters.– Hormonal induction with hCG was done

PASSIVE INTEGRATED TRANSPORDER (PIT)

• The brood fishes were sexed and tagged with Passive Integrated Transponder (PIT) tags in order to maintain the breeding history.

• The PIT tag is a device to permanently mark fishes internally with radio frequency tags.

1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 20130

5000

10000

15000

20000

25000

30000

35000

40000

45000

50000

Series1; 43395

Chart Title

TON

NES

GLOBAL PRODUCTION OF COBIA

SOURCE:-http://www.fao.org/fishery/culturedspecies/Rachycentron_canadum/en

Production trends1997- 9 tonnes2013- 43395 tonnes

• Of the production reported to FAO in 2004, 80.6 percent was produced in China and all the rest in Taiwan Province of China. The total value of the global production of this species in 2004 was USD 36206000.

• Cobia aquaculture production has been steadily expanding in Asia, primarily in Taiwan, Vietnam and China, but also in other Southeast and Indo-Pacific Asian countries including the Philippines, Indonesia, Iran and Reunion Island.

CONCLUSION• Cobia, a fast growing potential marine candidate species for the future, which

has already been gaining momentum in China, Taiwan, Indonesia, USA, Vietnam, Australia, etc. could be developed for culture in India.

• Encourages more farmers to undertake cobia culture (hatchery and farming) for livelihood support.

• 20% of the currently unutilized shrimp farms could be converted into productive cobia farms with minimum investment.

• Effective utilization of near shore waters for cobia farming in floating cages.• Innovative value added fish products will be introduced in domestic and

export markets. • Technologies developed would be transmitted to the fisherfolk to raise their

income through cobia culture.

REFRENCES• Successful seed production of cobia Rachycentron canadum and its prospects for

farming in India. G. GopakumarMarine Fisheries Information Service T&E Ser., No. 206, 2010

• Major achievements of researchMD/IDP/03 - Broodstock development, captive breeding and seed

productiontechniques for selected marine finfishes and ornamental fishes (2009-2012)(AND)

FISHCMFRISIL201202400024 - Development and standardization of seed production technologies for selected high value finfishes and shellfishes (2012-2014)

• Broodstock development & seed production of cobia rachycentron canadum Dr. A. Gopalakrishnan

• http://www.thefishsite.com/articles/1234/seed-production-of-cobia-in-india/• http://eprints.cmfri.org.in/8456/• http://www.fao.org/fishery/culturedspecies/Rachycentron_canadum/en