No-one seems to know why the fish keep dying at King Salmon’s Waihinau farm in Pelorus Sound – or if they do they aren’t telling us.
King Salmon’s aquaculture general manager Mark Preece recently commented that up to seven per cent of fish were dying each day at the Pelorus Sound marine farm. Testing by the Ministry of Primary Industries (then known as Agriculture and Fisheries) confirmed the fish were clear of all known viruses and bacterial diseases.
Testing had ruled out site and seabed conditions, including low oxygen levels, said chief executive, Grant Rosewarne.
“In all our years of salmon farming we have never known the seabed to contribute to a high rate of mortality and it is not something (the ministry) has identified as a possible cause of concern.”
Ecologist Rob Schuckard, of French Pass, recently questioned why King Salmon had not followed protocol provided by Cawthron, their science provider, for managing its Waihinau Bay and Forsyth Bay sites between 2010 and 2012.
An independent science report showed the worst pollution under a King Salmon farm was at Waihinau in 2009, Mr Schuckard said.
Hydrogen sulphide gas, which was harmful to fish, was present and copper and zinc levels exceeded levels allowed under their resource consent.
Advice was that it would take eight or more years for the seabed to recover but after being fallowed in early 2010, the site was reoccupied only 18 months later.
And this from the Government aquaculture site; Seabed Effects.
Salmon farms affect the seabed directly beneath them through faeces and uneaten feed falling to the seafloor. These organic-rich particles can alter the physical, chemical and biological nature of the seabed. Organic enrichment increases microbial activity that, in turn, can lead to oxygen depletion in the sediment (and subsequent changes to biodiversity).
Possible causes included combined effects of towing the farm from Forsyth Bay to Waihinau in November 2011 (unlikely as this was over three months ago), high water temperatures last summer (‘yeah right’ – last summer was hardly a scorcher) and seal attacks (laughable). An infectious disease, or a one-off event such as an algae bloom (the irony), were other possibilities.
Maybe it had something to do with stuffing tens of thousands of these fish into an environment that is nothing like they have evolved to deal with. It is interesting that this has not been offered up as a potential cause.
With National running the Ministry of Primary Industries like a corporation it is likely King Salmon will be confirmed disease free again in the future. King Salmon like to talk about how it is in their best interests to keep the water clean and disease free but at the end of the day they are a for profit foreign-owned company -nothing more and nothing less always pushing the limits.
King Salmon’s chief executive, Grant Rosewarne, has said “testing by the Ministry and King Salmon, in New Zealand and overseas, had failed to discover what was causing fish at Waihinau to become emaciated, stop eating then die”. He continued: “The healthy fish are staying healthy and the affected ones are slowly dying off.”
So only the affected fish have a problem Mr Rosewarne and they are slowly dying, so really there is ‘no problem’ and hey, the healthy fish are staying healthy. Well, that’s until they start dying!
But every cloud has a silver lining:
Dead fish are rendered at a temperature above boiling point to make fertiliser, pet food and animal feed now, instead of being dumped in the Blenheim landfill.