Effects of biofouling on shellfish aquaculture

The culture of oysters, clams, scallops, and other molluscs is collectively one of the fastest growing sectors of the aquaculture industry. An inherent issue with shellfish culture methods, particularly for off-bottom culture (i.e. floating trays, racks, long lines, strings, rafts), is biofouling. This can occur directly, by biofouling of the animals themselves, or indirectly, by fouling of cages, nets, filters, and other equipment. Problematic biofouling species have been identified and segmented into six groups: algae, barnacles, mussels, tubeworms, ascidians and hydroids. Controlling and mitigating biofouling can result in significant costs for commercial shellfish culture operations

Aquacultural production of mangrove oyster, Crassostrea gasar, in tidal waters of Niger Delta, Nigeria

Aquaculture or fish farming is a developing industry in Nigeria with potentials to make significant contribution to food security, livelihood, socioeconomic status, and the nation's economy. The aquaculture industry has grown substantially the last decades, both as a result of the over-fishing of wild fish populations, and because of the increasing consumer demand for fish meat. Oyster production around the world is becoming a growing industry since natural production is decreasing. The main species used for culture belong to Crassostrea genus and are in use for aquaculture. The native mangrove oysters are an important group of shellfish, exploited along the coasts and estuaries where they are naturally found. Mangrove oysters are found naturally in abundance in the brackish water creeks of Bayelsa, Delta and Rivers states, attached to the aerial roots of red mangrove vegetation, Rhizophora racemosa

The effects of culture system on growth and appearance of the mangrove oyster, Crassostrea gasar

The effect of culture system on the growth and appearance of the mangrove oyster, Crassostrea gasar, was studied. The off-bottom culture method was used under two culture systems of continuous and periodic submergence in two tidal ponds, designated A and B, respectively. The level of water was regulated in pond A while it was allowed to flow freely in pond B. The oysters were submerged in pond A and in pond B, were only submerged at high tide and exposed to air at low tides. A total of 375 oysters were used in each of the ponds at a stocking density of 75 per cage. Growth and appearance in the oysters were monitored monthly. Final mean length and weight: 50.3 mm ~c 6.68 SD, 20.8 g ~c 6.53 SD, and 52.3 mm ~c 7.14 SD, 18.8 g ~c 5.73 SD recorded for ponds A and B, respectively. No statistically significant differences were observed (P<0.05). Oysters from pond A appeared brittle, rough and unattractive and oysters from pond B were strong, neat and attractive. Salinity of 10-18 ppt and water temperature of 26~'C - 35.7 ~'c was recorded. The results revealed favourable growth under both culture systems but the unattractive appearance of oysters from pond A, made the oysters from pond B to show comparative consumer preference. However based on yield only, pond A is of greater advantage for the culture of mangrove oysters

Exploitable socio-economic benefits of mangrove oyster culture to the people of Niger Delta

The Niger Delta, a 30,000 km2 wetland of global ecological significance is located at the southernmost part of Nigeria. The Delta is dissected by a dense network of rivers and creeks of saline and freshwater surface bodies. The brackish water (saline) sector consists of estuaries and intertidal mangrove swamps; the total brackish water area for the Niger Delta estimated at about 7,415 km2. The mangrove oysters grow chiefly in brackish water creeks of Bayelsa, Delta and Rivers States, found attached to the aerial roots of the mangrove Rhizophora racemosa (Red mangrove). Mangroves are salt-tolerant evergreen forests found along sheltered coastlines, shallow-water lagoons, estuaries, rivers or deltas; stands stretching 30-40 km inland with an estimated area of 997, 700 ha in Nigeria. Aquaculture has an important role in the development of many national economies and plays a key role in rural development. The abundance of a natural population of mangrove oysters in the Niger Delta makes seed collectors and growing easier and inexpensive. The culture of mangrove oysters by the locals will contribute significantly to economic growth, increases income and food security, efficient utilization of surplus rural labour and reduced social problems, poverty alleviation, and social stability. This paper enumerates the culture and socio-economic benefits derivable from the practice of aquaculture through the sustainable culture of the native mangrove oysters