'This is the third time in a decade that MOWI has brought back proposals for a large-scale fish farm at Canna' (NTS)
Scottish conservation charity objects to Mowi's proposal for large salmon farm off Canna
Wednesday, August 21, 2019, 03:00 (GMT + 9)
The National Trust for Scotland (NTS) has written to Highland Council to express its opposition to to a large fish farm that Mowi Scotland wants to create off the Isle of Canna, seting out a number of concerns about its potential risks to the marine environment and tourist based economy.
The conservation group explains that its concerns are exacerbated by the scale of operation and its proximity to one of the most highly designated and important marine environments in Scotland.
The impacts fall within the following areas:
- Designated and other priority Marine Features within the Marine Protected Area
- Wild Atlantic Salmon and Sea Trout in surrounding areas
- Landscape features within the National Scenic Area (NSA)
- Navigation within Canna Harbour and the adjacent anchorage
- Operation of Canna Harbour
- Tourist industry for the island
The conservation charity highlights that the proposed fish farm is located within the biologically richest part of the Small Isles Marine Protected Area. “It represents probably the worst location that could have been chosen in this respect and it is essential that a highly precautionary approach is taken in assessing its potential impact.”
NTS claims that salmon farms are a major source of sealice larvae in the marine environment. These larvae have been shown to be present at levels that pose a threat to wild salmon and especially sea trout at distances at least 35 km from farms. The proposal therefore needs to assess the threat posed to salmon and seatrout populations within this zone.
The NGO says that the proposal is for a farm with a maximum biomass of 2,500t of salmon which can be expected to discharge annually the same amount of waste as a town of 33,000 people (the population of Oban is 8,500 in the winter, rising to about 25,000 in the summer).
“All of the waste is untreated and can have a devastating impact on the seabed. The proposal indicates that hydrographic modelling will be used to predict where this waste will fall and indicates we believe to be an unrealistically small footprint for this impact. Recent work by SEP has shown that in conditions of strong and complex tidal currents, such as those prevailing in the Sound of Canna, waste can accumulate up to 4km from the farm site. This long-range deposition is not well captured by existing hydrographic modelling capacity,” warns NTS.
The farm also falls within two marine Special Protection Areas (SPAs), designated in part for Manx Shearwaters.
The modelling tools promoted by SEPA provide robust predictions in most cases, requiring relatively little site-specific information. Nevertheless, the quality of the model outputs is dependent upon good quality data and careful implementation of the models and interpretation of their results.(Photo: SEPA)
“One of the greatest threats to the SPA on Canna is from introduced predators. Foremost amongst these are rats, which are currently absent from Canna, having been eradicated in 2006 at considerable effort and expense”, says NTS.
It underlines that invasive non-native species also pose a risk to features of the MPA, particularly species such as the carpet sea-squirt, known to be present in a number of harbours on the mainland. Therefore, NTS calls for the risk of introducing these through the operation of the fish farm needs to be fully assessed.
NTS also notes that the proposed farm site is within 1km of a designated seal haul-out site, and that it would greatly increase the potential for interactions with seals (predation, entanglement) and may result in the need for control measures, including lethal control.