Farmed salmon killed by disease leaps to 8.5 million

from Sunday Herald, 10 February 2013 

The number of salmon killed by diseases at Scottish fish farms leapt to over 8.5 million last year, sparking fresh doubts about the sustainability of the £1 billion industry.

New figures released by the Scottish Environment Protection Agency (Sepa) reveal that losses from all salmon farms have reached nearly ten per cent of their production. The main problem has been the spread of Amoebic Gill Disease, blamed by some on the warmer seas caused by climate pollution.

A mountain of 13,627 tonnes of dead fish had to be disposed of in 2012 by 230 fish farms along the west coast and on the islands, compared to 9,717 tonnes in 2011 and 7,159 tonnes in 2010. The worst problems were in Shetland, where 2.4 million salmon died.

The mass mortalities – known in the industry as morts – have also raised questions about how such large amounts of diseased waste are safely disposed of, and how the process is regulated. Sepa and local authorities both say it is not their responsibility.

Farmed salmon is Scotland’s single largest food export, with a worldwide retail value of over £1 billion and major sales in the US, China and France. Production has risen fivefold since 1990, and now involves 27 companies employing more than 1,000 people in rural areas to produce over 158,000 tonnes of salmon a year. 

The industry, backed by the Scottish government, is hoping to continue the boom with a further 50% increase in the production of all farmed finfish by 2020. But such ambitions may now suffer because of the mounting mortalities, and the financial problems they are triggering.

Two of the leading Norwegian-owned fish farm companies, Grieg Seafood and Marine Harvest, have recently reported major production losses from diseases in Scotland. Analysts have suggested that the industry could forfeit more that £30 million in revenue.

Sepa released detailed information about the deaths at fish farms over the last three years in response to a request from the Sunday Herald. The figures showed that the huge weight of prematurely dead fish that had to be disposed of nearly doubled between 2010 and 2012.

It was Grieg Seafood, which owns Hjaltland Seafarms in Shetland, that suffered the most mortalities, losing a massive 4,661 tonnes of salmon at 35 farms. Seven of the ten fish farms with the worst mortality rates were run by the company. 

Second in the dead fish league was the foreign-owned Scottish Salmon Company, with 2,374 tonnes of mortalities at 39 farms. The other major operators – Meridian Salmon, Marine Harvest and Scottish Sea Farms – also suffered major losses (see tables below).

Amoebic Gill Disease can suffocate fish by blocking their gills, and can also render them too weak to withstand the chemical treatments commonly used to combat sea lice infestations. In the last few years, the disease has spread from Tasmania in Australia to America and Europe, and was first reported in Scotland in 2011. 

Anglers and environmentalists pin the blame on the intensive production methods used in salmon cages, and are demanding a halt to the industry’s expansion plans. “It is clear from these massive mortality figures, that there are major problems,” said Hugh Campbell Adamson, the chairman of the Salmon and Trout Association in Scotland.

“Any intensive farming system, whether on land or in the sea, is highly prone to disease outbreaks. When a large number of animals or fish are closely confined, the likelihood of endemic disease is greatly increased.”

He was worried that the diseases could spread to wild fish. “Until it is crystal clear what is causing these deaths, and whether that cause of mortality is transferrable to wild fish, then surely the government and the industry must stop any expansion.”

The association’s aquaculture lawyer, Guy Linley-Adams, argued that salmon farms had to be kept apart from wild fish. “It must mean aquaculture in closed containment, where there is a biological separation between farmed and wild fish,” he said.

Don Staniford from the Global Alliance Against Industrial Aquaculture warned that diseases were crippling the salmon farming industry. “Scottish salmon farming's debt and mort mountain is piling up higher than Ben Nevis,” he said. 

“The stench is so powerful that the CEOs of the Norwegian companies controlling over 80% of the industry can smell dead farmed salmon from their head offices in Norway where they are counting their losses in the millions.”

Grieg Seafood declined to comment, referring inquiries to the Scottish Salmon Producers’ Organisation (SSPO). It argued that the survival rate of farmed salmon was “vastly higher” than wild salmon.

“A proportion of the elevated mortality during the last year is a consequence of an influx of naturally-occurring amoeba from the wild marine environment which has impacted global fish populations and has recently arrived in Scotland,” said the SSPO’s chief executive, Scott Landsburgh. 

“Naturally occurring losses are unfortunately a part of all animal production,” he added. “With as much as 240,000 tonnes of farmed salmon growing in Scottish waters at any one point, the losses represent a small percentage of total production.” 

The Scottish Salmon Company pointed out that that was trying to keep mortality rates as low as possible. “We ensure that all fish stocks are rigorously monitored so that fish mortalities are identified and disposed of quickly, in accordance with industry regulations agreed with statutory environmental agencies,” said the company’s chief executive, Dr Stewart McLelland.

The huge rise in fish farm deaths

year / tonnes of dead fish / number

2012 / 13,627 / 8.5 million
2011 / 9,717 / 6.8 million
2010 / 7,159 / 5.5 million

The companies with the most dead fish

company / tonnes of dead fish in 2012 / number

Hjaltland Seafarms / 4,661 / 2.4 million
Scottish Salmon Company / 2,374 / 1.5 million
Meridian Salmon / 1,913 / 1.8 million
Marine Harvest / 1,897 / 1.4 million
Scottish Sea Farms / 1,659 / 725,000
Loch Duart / 822 / 525,000
Others / 301 / 150,000

The 10 farms with the most dead fish

site / company / tonnes of dead fish

Swining Voe Site 3, Collafirth Ness, Shetland / Hjaltland Seafarms / 551
Setterness South, Shetland / Hjaltland Seafarms / 514
Skewart Holm, Linga, Shetland / Hjaltland Seafarms / 495
Trilleachan Mor, North Harris / Scottish Salmon Company / 490
Collafirth Delting Site 3, Shetland / Hjaltland Seafarms / 448
Setterness North, Shetland / Hjaltland Seafarms / 366
Linga South, Shetland / Hjaltland Seafarms / 297
Brindister Crossroads, Shetland / Hjaltland Seafarms / 248
Sron, Lochalsh / Marine Harvest / 234
Cava South, Orkney / Meridian Salmon / 226

source: Scottish Environment Protection Agency

The spreadsheet summarising fish farm mortalities in 2010, 2011 and 2012 released by the Scottish Environment Protection Agency can be downloaded here (188KB Excel).

Comments

[Alaska Fishing Tackle]

Well I guess when a large number of fish are closely confined, the likelihood of endemic disease is greatly increased. I think this is the reason for fish kills.