It is now six weeks since the Supreme Court released its judgement on New Zealand King Salmon’s expansion in the Marlborough Sounds.  The Court found that a proposed salmon farm at Paparua, Port Gore, did not uphold the principles of the New Zealand Coastal Policy Statement.  The judgement means that only three of the original nine new farms proposed by NZKS will go ahead.  While the judicial implications of the decision have yet to be fully explored, one certain outcome is an increase in awareness of the effects of intensive aquaculture amongst the general public.  In light of the high degree of concern expressed by individuals and groups throughout New Zealand in response to salmon farming in Marlborough, perhaps it is time for a public discussion around international innovations in aquaculture, and how these might be appropriate here.

An interesting recent blogpost on Triple Pundit introduced one of the many examples of land-based aquaculture that have proliferated in the last decade.  In the inland US state of Indiana, Bell Aquaculture (video below) raises a variety of freshwater fish in large indoor tanks, using an almost closed-loop system that filters and recirculates 99 percent of water used.  Rather than using wild-caught fishmeal as the sole feed source, Bell also uses plant-derived feed pellets from largely local sources, and converts offal, off-cuts and faeces into garden fertilisers.  While land-based aquaculture has a long history in Asia and Europe, and is expanding in North America and the Middle East, the majority of fish farmed in New Zealand are raised in enclosures in coastal waters. The Cawthron Institute has published a report on the feasibility of land-based aquaculture in New Zealand.  It is certainly not a panacea for the problems associated with intensive fish farms such as those involved in recent controversies in the Marlborough Sounds, as land-based systems, even those that recirculate water and nutrients, are also very resource-intensive operations with high infrastructure costs.  But it is a technique that is worth considering as New Zealand searches for more sustainable sources of fish protein into the future.

Other options include ‘fish ranching’, where fish are not enclosed for a large part of their life cycle.  Most experiments with ocean ranching have involved species with a strong homing instinct such as salmon.  Juvenile fish are often reared to smolt stage before being released to the ocean to gain weight as part of a natural ecosystem.  At the end of their life cycle they return as mature adults to the point of release, where they are harvested.  Similar systems have been established in Iceland, Japan and the United States, with various degrees of success.  Also interesting are developments in offshore finfish mariculture, where enclosures are suspended in the water column a considerable distance from land.  The deeper waters and stronger currents in these environments may avoid – or at least dilute – some of the direct nutrient pollution experienced by operations in more sheltered coastal waters such as Marlborough.  These represent the potential for quite remarkable changes in finfish farming, especially in light of the extraordinary variety of stresses being placed on inshore waters around the world and here in New Zealand.