|By goGreen | May 31, 2012|
Mangrove forests occupy the area of the coastal zone between the mean sea level and extreme high water of spring tides. They thrive in sheltered tidal flats, coves, bays, and river estuaries. Usually, they are associated with thick stands of medium-sized and even aged trees, nipa palms and other herbaceous plants.
Mangroves are very important to marine life, according to the Laguna-based Philippine Council for Aquatic and Marine Research and Development (PCAMRD). They serve as sanctuaries and feeding grounds for fish that nibble on detritus (fallen and decaying leaves) trapped in the vegetation, and on the bark and leaves of living trees.
A study done by the Department of Environment and Natural Resources (DENR) showed that mangrove forests are home to 68 species of fish, 54 species of crustaceans, and 56 species of gastropods.
Among the fishes that thrive best are the mangrove snappers (locally called banagan). They are found in, under, and around the root structures. It has been observed that they patrol the entire root structure looking for food and using the entangled roots as protection from larger predators.
The fish is typically greyish red, but it can change color from bright red to coppery red. It has a dark stripe running through its eye if you look at it from the top when it is underwater. Its size ranges from one to three kilograms but many biologists have now confirmed that a 13.4 kilograms mangrove snapper was speared off of the coast of Louisiana in the United States.
They are called snappers for a reason. “Keep your fingers away from its mouth,” Brown warns. “It has very sharp teeth and is very willing to use them.”
The upper jaw of mangrove snapper has two canine-like teeth that are used to tear into their food. Once caught, their jaws will lock down hard on a hook. As the hook is being removed they snap their jaws open and shut with great force, often catching a careless angler by surprise.
In the Philippines, mangrove snapper has a ready market -particularly in restaurants. “They are a delicious fish,” says Dr. Rafael D. Guerrero III, a fishery scientist who is affiliated with National Academy of Science and Technology.
Unknowingly, mangrove snapper can be reared in captivity. In fact, it is one of the promising high-value finfish species for culturing in sea cages, such as those in the mariculture parks being developed by the Bureau of Fisheries and Aquatic Resources in different parts of the country.
Dr. Guerrero, who was the former executive director of the PCAMRD, recommends culturing mangrove snapper “if the fingerlings are available.”
In Roxas City, one fishfarmer actually raised mangrove snapper in his pond. For nursery operation, he stocks 700 pieces of one-inch fingerlings in a cage measuring 4 meters by 6 meters and 1 meter deep. That means 29 pieces per cubic meter. In 25-30 days, the fingerlings quadrupled their size.
Double net is used in the cage with a mesh of 0.5 centimeter and outer net mesh is #17. Feeding is done at least three times a day, initially at 8% to 10%of body weight. For the first 10 days, feed is finely chopped shrimp or fish. From the 11th to 30th day, trash fish is fed.
For grow-out operation, cage with the same dimensions as above may be used. A total of 150 four-inch fingerlings are stocked. These are cultured for 6 to 7 months with a target harvest size of 750 to 800 grams each.
The cage is double net with #17 net mesh. The net is changed at least three times during the whole culture period, or depending on the degree of fouling.
The fish are fed with chopped trash fish based on demand up to satiation, or initially at 6 to 8 percent of average body weight and adjusted based on consumption and response. The target feed conversion ratio is 8-10 kilograms of trash fish for every kilo of fish harvested.
If in the past fingerlings of mangrove snappers are available only from the wild, such is not the case today. In fact, fingerlings are available throughout the year — from hatchery. Those who want to raise mangrove snappers in their ponds can buy their fingerling stock from Finfish Hatcheries, Inc. (Fill), a member of the Alcantara Group of Companies, based in Alabel, Sarangani province.
“We deliver fingerlings up to the nearest airport of the buyer nationwide,” says Rene B. Bocaya, the Fill national sales manager. The minimum order is 10,000 pieces per delivery.
Finfish Hatcheries, Inc.
2286 Alsons Bldg, Pasong Tamo Ext., Makati City
Tel: (02) 815-2142
SOURCE: Entrepinoy ATBP