Atlantic Halibut

Halibut farming uses both land-based and marine net-pen sites. Appropriate siting, design and construction of on-shore and marine facilities is essential to limit adverse impacts on the environment and natural ecosystems.

Land-based aquaculture facilities (both PAS and RAS) involve a greater level of complexity and utilise much more technical equipment than open-water systems (e.g. net-pens), especially intensive production farms with numerous growing units (e.g. tanks)^{1, 2}. Major components include:

• Water abstraction and transfer
• Water treatment and wastewater discharge
• Production units
• Equipment and space for: feeding / feed storage; internal fish transport and size grading; transport of goods and services in and out (e.g. feed, staff, harvested fish); monitoring of the culture environment (e.g. water quality parameters)

There are many factors to be considered in locating a land-based aquaculture facility. Many will be project-specific depending on the type and scale of the operation and the environmental requirements needed by the cultured species (e.g. temperature, salinity, etc.)³.

The physical, locational requirements for a large marine PAS or a RAS are likely to be somewhat similar. Both need to have an adequate area of land, which is relatively flat and easy to develop. Capital costs for purchase/rental of the land needs to be appropriate in order to make an on-shore aquaculture facility viable¹. In addition, it needs to be close enough to water levels in order to reduce pumping costs³. Energy is one of a number of critical operating costs that influence the location of PAS or RAS farm developments⁴. For that reason, low-lying sites in areas with low tidal range are the most suitable locations for PAS.

On-shore aquaculture systems often require large buildings, may increase road traffic (e.g. goods and service flows) and generate noise (e.g. generators, pumps, compressors). These impacts may be of concern if located in sensitive coastal areas. Designing, building and operating an on-shore aquaculture facilities must, therefore, be undertaken with due regard to the sensitivities of the local area (e.g. not disturbing the skyline, screening by trees or other structures, respect for other coastal amenities/users), and local infrastructure (e.g. road network capacity). Working through the necessary planning policies is vital.

When halibut is farmed in floating net-pens within navigable water bodies, it must be ensured that facilities do not impinge and restrict movement of boats, aquatic animals and the water itself. There may also be concerns over the visual impact of siting net-pens in the areas of natural beauty; in such areas it is important that the design, construction and colour of farm facilities are sympathetic with the landscape in which they sit.

Halibut farmers should ensure all possible management measures are taken to protect stocks from predators. This may be more relevant to PAS rather than RAS facilities which are more contained and isolated from the external environment. Deterrents, scarers and increased on-site activity may be effective. Lethal methods of predator control should only be resorted to when appropriate licences are in place and the species are not threatened in any way.

In all cases, national and local laws should be adhered to and all farms should have the required licences, permits and registrations in regards to their site and its operations and keep documentation as evidence of compliance.