Pacific Oyster Mortality Syndrome (POMS) is a disease caused by a virus. POMS is harmless to humans but lethal to oysters causing up to 90 per cent mortality in a crop of millions within days. It weakens the oyster causing the shells to open and die.

 

The first POMS outbreak was observed in 2007 in France which nearly wiped out the oyster industry and in 2010, New Zealand's Pacific Oysters succumbed to the virus that causes POMS, OsHV-1. Eight months after that POMS entered Botany Bay's Georges River in Australia. Again, huge losses were seen at Pacific Oyster farms. 

By 2013, POMS had spread to a second NSW estuary, the Hawkesbury River; known for large production of oysters in NSW. The disease killed over 10 million oysters over three days. Then, in January 2016, POMS made it way to Southern Tasmanian waters. It was considered to be an unlikely destination for POMS in Australia as the disease preference for water temperatures above 21-22°C. The Tasmanian industry lost 50 employees and 60% of the state's growing areas were affected by it.

Industry survival lay in the hands of a genetic program set up by the industry own Australian Seafood Industries (ASI). Prior to POMS reaching New Zealand, ASI had been working closely with CSIRO and the NSW Department of Primary Industries (DPI) on genetic improvement of Pacific Oysters through selective breeding. Its research was focused on creating larger and robust Pacific Oysters, but the direction quickly changed once POMS attacked.

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Our focus was to create a POMS resistant oyster as well as maintaining genetic improvements for traits of key importance to the Pacific Oyster industry.

After the POMS breakout in Georges River, oysters from ASI's 80 distinct family 'lines' were relocated from clean locations to the 'diseased' estuary to test the genetic difference in POMS survival. NSW DPI ran field trials and CSIRO analysed survival data for the different genetic lines. CSIRO found that there was a strong genetic basis for POMS survival.

Since then, ASI has been in partnership with NSW DPI and CSIRO in a genetic breeding program for POMS resistance.  The breeding program is about accumulating and increasing the frequency of those genes with each new generation. The target is to create an overall level of POMS resistance with the commercial oyster population that the Pacific Industry could work with.

Currently ASI is in its sixth generation of POMS selective breeding. Some of the elite performing lines (one year old animals) have shown even higher levels of resistance, up to 80-90 per cent. However, the challenge for ASI is that the mortality rates of 2 - 3 month old spat are still much higher than those for one year old stock. ASI's current research target is to have a POMS resistant Pacific Oyster spat with average survival of >80% (for diploids at 2 - 3 months) to a POMS outbreak available to all Australian Oyster farmers.

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