Offshore mariculture

February 2019: Offshore mariculture is a viable and emerging alternative to land-based coastal aquaculture. It uses submersible cages in high energy off-shore environments that allow producers to raise large numbers of fish in small spaces such as in the Caribbean. However, off-shore mariculture struggles from insufficient capital investments, regulatory issues, and environmental concerns.

Information

Rising demand for animal protein, in particular seafood ,is predicted to further increase with a growing population. However, many wild fisheries are already over-exploited and current fishing methods are unsustainable. A new study explores the potential of offshore mariculture in the Caribbean, also known as open ocean aquaculture, from a bio-economic angle. Offshore mariculture is a promising emerging alternative to land-based coastal aquaculture that suffers from high environmental impacts and limited available space. Offshore mariculture uses submersible cages that can move up and down the water column and are anchored on the sea floor. The operation targets deep and open waters with strong currents. The high-energy off-shore environment allows fish faeces and nutrient effluents to be diluted. This avoids impacts on water quality and sensitive near-shore habitats such as coral reef and sea meadows.

Implications & Opportunities

When considering socio-economic, political, and environmental risks, offshore farming is a viable alternative to land-based coastal aquaculture, especially for locations such as the Caribbean where space is limited. Applying open ocean aquaculture technologies could lead to the Caribbean expanding their fish industry to producing 40 million metric tons of seafood in less than 1.5% of the country’s economic zone. Further, the multi-functional use of offshore waters could enable developers to re-purpose equipment for aquaculture or to introduce polyculture trials such as fin fish and oysters. One example is the Hubb-Sea World Research Institute that repurposed a retired oil platform as an experimental open ocean aquaculture facility.

Limitations

Despite the technology showing a large potential for sustainable aquaculture, there are several main barriers and limitations. The new industry represents a high risk for foreign investments and suffers from a negative image due unsustainable production methods from coastal aquacultures, making capital insufficiently available. Up-front capital costs are high due to higher maintenance costs of offshore facilities and the need to find sufficiently profitable species. Further, open aquaculture can compete with some marine resource users in deep waters and many critics are concerned over the use of antibiotics or cultured fish escaping in open waters. The concept of using roaming cages to rear fishes in open waters is still in its development stage due to its regulatory and legal implications.

Sources

Lennon, R., Clavelle, T., et.al. (2019). The ecological and economic potential for offshore mariculture in the Caribbean. Nature Sustainability, 2(1), 62. DOI: 10.1038/s41893-018-0205-y

FAO. (2013). A Global Assessment of Offshore Mariculture Potential from a Spatial Perspective. Retrieved from http://www.fao.org/docrep/017/i3100e/i3100e01.pdf