June 8, 2006
Runaway salmon farm returns home after 3 months
The NZ King Salmon Co, a new Zealand aquaculture company, announced Tuesday (6 Jun) the successful return of its Te Pangu farm to its Tory Channel site after it slipped away from its moorings in early March.
After the farm drifted off, the company had first taken stock of the situation and investigated its likely causes.
Mooring consultants, independent experts and insurance assessors have not been able to agree on a single cause as to how the farm could have floated off by itself.
The cause was, naturally, excessive pressure.
The company said that an uneven distribution of pressure on one section of moorings caused the problem. The extensive array of 31 moorings did not evenly spread the load and this resulted in the snapping of mooring lines due to excessive loads. The failure then allowed the farm to skew across the prevailing current, increasing the mooring load which resulted in a series of mooring line breakages that cause the farm to drift off.
In an effort to get the farm back, the company hired expert mooring advice to re-capture the farm. While doing so, it also repaired the cage infrastructure and grow-out nets and made other preparations for the return of the prodigal farm.
The company had intentionally timed the return of the farm so that it was buoyed by supportive tides.
However, the runaway farm did not escape unscathed from its 3-month sojourn. Losses were mainly in very small fish, but these would result in fish shortages next autumn, when they would have reached harvest size.
The company has been able to mitigate the fish loss with additional smolt stocks while other damages have been covered by insurance
Most losses had probably resulted from the lack of feed and natural predators in the area, the company said.
To avoid a repeat of this event, NZ King Salmon has strengthened the mooring system to keep the farm in place while adding a tensioning management plan designed to ensure that the pressure load is always evenly distributed.
