Chile salmon authority says ISA virus under ‘full control’ as sanitary conditions improve

August 19, 2014, 4:20 pm

Chile's salmon producers have experienced improved sanitary conditions in the first half of 2014, although the Piscirickettsiasalmonis disease (SRS) remains the major cause of mortality in salmonids, said a report by authorities.

After a slight decrease in the number of productive centers operating in the first six months of the year, biomass present in sea cages has gone up by 10% year-on-year, reveals the latest report on Chile's sanitary situation by the aquaculture management body Sernapesca.

The worst years of the infectious salmon anemia (ISA) crisis -- between 2007 and 2010 -- have been overcome, with this year's last outbreak detected in January, at Invermar's Traiguen center, shows the report.

Sernapesca issued an order to prematurely harvesting the farm, and the salmon producer had to advance harvesting in early May.

"With analysis conducted in the focus and nearby areas, today we can rule out the presence of new outbreaks of this virus in the area," said Jose Miguel Burgos, national director at Sernapesca.

Although the Sernapesca director said ISA is "under full control", the virus is still present in Chile, and new cases are expected in Atlantic salmon under stress factors in the regions of Los Lagos, Aysen and Magallanes, the report reads.

Lower mortality, high SRS impact in trout

Mortality rates in salmonid species -- Atlantic salmon, coho and trout -- are lower in each one of the six first months of this year, compared to H1 2013, shows the report.

January was the month with highest salmonid mortality (1.4%), while June showed the lowest level of this year's first half (0.88%). Mortality percentages follow the expected seasonal behavior, the report reads.

Monthly mortality in Chile's sea cages, January 2013 - June 2014

Monthly mortality in Chile's sea cages, January 2013 - June 2014

By end of June, SRS was the cause of above 70% mortality rate in Atlantic salmon (79.4%) and trout (76.4%), but the last was the most hit, since trout is the only species showing a decrease of production.

"[SRS] affects mainly centers in the last stage of the productive cycle, with higher prevalence and severity in trout species," the report says.

As Undercurrent reported before, some large Chilean farmers -- such as AquachileCamanchaca or Blumar -- announced plans to suspend trout production due to biological challenges that caused high mortalities in the cages.

Thus, while Atlantic salmon has increased biomass by 19.2% in H1, trout has experienced a 16.8% biomass decrease, the report reads.

"Trout production has had important losses due to high mortality and lower harvests, so we are challenged to modify our control program in order to decrease the impact of this desease," Burgos said.

The 62,327t  drop of trout production by end of June, already hit total aquaculture production in Chile, down by 11.3% to 524,000 metric tons, according to Chile’s undersecretariat for fisheries and aquaculture, Subpesca.

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