Sustainable Shellfish Aquaculture For the Gulf of Guinea

The Gulf of Guinea is a highly productive ecosystem with bountiful natural and marine resources. Its oil-rich offshore waters are also rich with upwelling nutrients for growing shellfish. The region has the potential to become a major producer of shellfish for feeding its population and generating foreign exchange from exports as its vast non-renewable petroleum resources are depleted.

Unlike all other forms of marine aquaculture, commercially grown bivalve shellfish have been identified as the only sustainable form of aquaculture that have no negative impact on the environment. Rather, shellfish aquaculture operations actually improve water quality by filtering out pollutants, sediments, and phytoplankton from the water column. Furthermore, shellfish remove nitrogen from the water helping to control and prevent harmful algae blooms.

Shellfish, such as oysters and mussels are one of the planet's most perfect foods containing enormous amounts of omega-3s. They are successfully farmed throughout the world and represent a legitimate use of the marine environment for sustainable food production.

Furthermore, “open ocean” farming is a new paradigm challenging traditional shellfish farming in bays and estuaries. The swift currents and upwelling in the open ocean supply ample food to promote faster growth rates and suspended long-lines prevent predation and parasites that impact shellfish in calmer shore waters.

Large Marine Ecosystem of the Gulf of Guinea

Sixteen countries border the Large Marine Ecosystem (LME) of the Gulf of Guinea: Angola, Benin, Cameroon, Congo, Democratic Republic of the Congo, Cote d'lvoire, Gabon, Ghana, Equatorial Guinea, Guinea, Guinea-Bissau, Liberia, Nigeria, Sao Tome and Principe, Sierra Leone and Togo. The LME covers an area of about 2 million kilometers, which has the largest continental shelf in West Africa and possessing some of the most productive coastal and offshore waters in the world.

The region surrounding the LME has an estimated population of 300 million and at the present rate of growth, this number is expected to double in 20-25 years. Fisheries are a major source of food security for the burgeoning population and a substantial source of foreign exchange for countries such as Angola, Cote d'lvoire, Ghana and Guinea. A large proportion of the population is affected by the overexploitation of the fisheries sector having widespread socioeconomic impacts on more than 500,000 men and women working along the coast in artisanal fisheries.

The Gulf of Guinea is rich in living marine resources supporting significant biomasses of plankton, tuna, sardines, mackerel, shrimp and other species. These include locally important resident stocks of shellfish supporting artisanal fisheries. Average per capita fish consumption is estimated at 20-25 kilograms, about double that of the world average, and marine fish provide over 80 percent of the supply. Annually, the region catches about 200,000 tons of fish, which is the same amount that it imports.

However, the Gulf of Guinea's complex trans-boundary straddling of migratory fish stocks have attracted large commercial foreign fishing fleets exploiting the abundant natural resource. The once-rich LME is now over-fished and terribly stressed creating a crisis for those who depend on fisheries for their livelihoods and jeopardizing food security for the region. Since the Gulf of Guinea's wild fisheries have reached or exceeded their maximum sustainable harvest, marine aquaculture is becoming an imperative for food security.

Shellfish for Habitat
Filter-feeding bivalve shellfish were once the global ecosystem engineers enabling prosperous habitats for other species and providing prodigious ecosystem services. A single adult bivalve can filter up to 50 gallons of water a day, allowing sunlight to penetrate so that foundations of the food chain can thrive.

The coastal and marine environments of the Gulf of Guinea are seriously polluted in the vicinity of large cities and an estimated 47 percent of the population lives within 200 kilometers of the coast. While the incidence of eutrophication (excess nutrients causing aquatic plant growth) is not widespread and tends to be episodic, there have been increased occurrences of harmful algae blooms in the Gulf of Guinea since 1993.

Shellfish remove nitrogen and other nutrients from the water and reduce eutrophication to help control and prevent harmful algae blooms. Consider that a weekly harvest of about 10,000 shellfish removes about 200 pounds of nitrogen per year. Thus, a shellfish farm of 1,000 acres would compensate for the nitrogenous wastes of about 50,000 coastal inhabitants.

Shellfish for Harvest
Shellfish are a healthful addition to a balanced low-fat diet, are much lower in saturated fat than pork or beef, and provide high quality protein. Moreover, shellfish contain significant amounts of heart-healthy omega-3′s, which are undetectable in chicken, beef and pork. Furthermore, shellfish are especially good sources of iron, zinc, copper, and vitamin B12.

The mangrove oyster of West Africa has promising commercial potential although the export market has not yet been adequately identified. Harvesting oysters have been part of the West African coastal cultures since living memory. Oysters grow on roots of mangrove trees and on submerged stones and rocks. Traditionally, they are harvested, processed and sold by women. Trials with the Perna mussel conducted in Angola showed promising results. It took only six to seven months to rear the mussels to commercial size and further trials confirmed that it was possible to harvest two crops a year.

Mussels have been cultivated for almost 800 years in Europe and have been a food source for more than 2,000 years. Amazingly, malnourished millions residing in the Gulf of Guinea Region are unaware of this delectable and nutritious food source. This provides an opportunity for mussels to become a local and versatile food source for increasing food security to the region.

From a harvest perspective, sustainable shellfish aquaculture would provide food security with a high-quality, high-value product for exports and for local consumption. From a habitat perspective, shellfish would provide valuable benefits to the Gulf of Guinea marine environment.

By Abdul Razak Haruna
Country Director,
KZO Sea Farms Inc.
Accra - Ghana.
[email protected]