Tuesday, January 4, 2011

Giant Grouper, Kerapu Kertang, Epinephelus lanceolatus

GG as they popularly known among the researcher and farmers. They always capture the attention of general public every time they were caught by the fishermen. Records shown they can grow to hundreds of kilogram and achieve an old age of 60 years old.

Giant Grouper caught in Perak. Source: Utusan Malaysia

In my previous post, Common Grouper Fishes Of Malaysia, I did mentioned how special and popular this fish to the local of Asian populations. Believed and beloved due to the potential of superpower that they might bring, the fish naturally gain popularity to all of us, the grouper interested people, be the farmers, fishermen, fish culturists, hatchery operators, researchers and the seafood lovers.  It have been said that GG is  very rich in protein and vitamins, high in calcium, which are beneficial for bone development, able to curb blood clot, having anti-cancerous properties and also good for brain development. As in many deep water fishes, the GG skin is high in collagen, the element that known to prevent ageing process especially to the skin if being taken regularly. Even the GG scales also reported to be very nutritious and having remedial effects. Every part of GG has its own special usage, from scales, bones, fins, lips, tails, skin, liver, intestine, gill, tongue, bladder, roe or even its sperm duct . No wonder it was so much being looked after, the buyers will not waste any part of the fish and will not waste their money on this fish. 

Due to its high demand in the markets and their maturity size, this species is now considered under the International Union for Conservation of Nature's (IUCN) Red List. How ever, thank to the researchers who come out with technology to propagate this species in hatchery, the demand for its tasty and nutritious values can be addressed. As in my many postings, I really feels that this is the way to overcome the problem of over fishing for all species of marine organisms be it as small as sea-horses to the giant whales. Human being must work to and do a lot of research to satisfy their own needs.

Distribution of GG. Source: fishbase.com
Giant grouper normally found in the reef associated waters and said to be the biggest bony fish in that ecology. They are common in the shallow water and used to be found in even brackish water. They feeds on crustacean, fishes and squids. Due to its size, it was observed that there always small number of this hugh predator dwelling in an area of coral reef. The big fish always found in their "home" cave from as shallow water of 4 meters up to 100 meters deep.

As being shown in the map above, this species is most widely and largest distributed among the groupers species but rarely found in all locations. It inhibit from  throughout the Indian Ocean, Pacific Ocean, Andaman Sea, Malacca Straits, South China Sea, covering a region from the Red Sea to South Africa and eastward to the Pacific islands up to Micronesian islands. In western Pacific from southern Japan southwards to Australia.  It covers tropical and temperates waters ranging from 29°N to 39°S, 24°E to 122°W.

Clean water in the coral area makes the best place for Giant Grouper.
Photo: Sim See Hong

According to a scientific report, based on their observation of  250g GG fishes that being cultured in the cages, this fish achieved its maturity in the fourth year. With an average growth rate of 19.51 to 22.76 gm/day and length increase at 0.035 to 0.58 cm/day, at the end of fourth year, its sizes were around 28.27 to 28.31 kg. Some reports says that GG can grow up to 400 kg.

The growth rate of 19.51 to 22.76 gm/day is considered very good growth rate indeed for aquaculture species. If our fish farmers stock their fry of 250 gm each, theoretically they only need an average of 64 days to get their GG to achieve market size 1.5 kg / fish! Even if we give another 64 days for its culture periods, this species IS still the 5 stars fish for all of us!  The same report confirmed that GG can achieve 1 kg weight within 4 months.  No wonder in Malaysia even GG fry price is around RM30 each. Hey, we not yet discuss the price of GG!
The 2009 Import and Export Market for Live Fish in Asia 
4 years old for maturity is considered not that too long for us to work with this species. Further, we know their weight during that time is around 28 kg and above. So, keeping our own broodstocks from our own fry, do the genetic selection process based on their growth rate could be our option for this species.

According to an assessment done in 2006, the small size GG price was around US$169/kg in HongKong. The small size GG (1.5 - 1.8kg/fish) were more preferred by the outlets in that market. HongKong was reported as the main importer for this species but some fishes were trans-shipped to mainland China. The other markets including South East Asian countries. I believe mainland China will become the major importer of this species in the very near future, and it will only be limited by the ability to supply the market size GG to that market by producing countries.

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