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        The ecological impacts of offshore aquaculture are somewhat uncertain because it is still largely in the research stage. Many of the concerns over potential offshore aquaculture impacts are paralleled by similar, well established concerns over inshore aquaculture practices.

Pollution

        One of the concerns with inshore farms is that discarded nutrients and feces can settle on the seafloor and disturb the benthos. The "dilution of nutrients" that occurs in deeper water is a strong reason to move coastal aquaculture offshore into the open ocean.How much nutrient pollution and damage to the seafloor occurs depends on the feed conversion efficiency of the species, the flushing rate and the size of the operation.However, dissolved and particulate nutrients are still released to the environment.Future offshore farms will probably be much larger than inshore farms today, and will therefore generate more waste. The point at which the capacity of offshore ecosystems to assimilate waste from offshore aquaculture operations will be exceeded is yet to be defined.

Wild caught feed

        As with the inshore aquaculture of carnivorous fish, a large proportion of the feed comes from wild forage fish. Except for a few countries, offshore aquaculture has focused predominantly on high value carnivorous fish.^[5] If the industry attempts to expand with this focus then the supply of these wild fish will become ecologically unsustainable.

Fish escapes

       The expense of offshore systems means it is important to avoid fish escapes.However, it is likely there will be escapes as the offshore industry expands.This could have significant consequences for native species, even if the farmed fish are inside their native range. Submersible cages are fully closed and therefore escapes can only occur through damage to the structure. Offshore cages must withstand the high energy of the environment and attacks by predators such as sharks.The outer netting is made of Spectra – a super-strong polyethylene fibre-wrapped tightly around the frame, leaving no slack for predators to grip.However, the fertilised eggs of cod are able to pass through the cage mesh in ocean enclosures.