Current affairs
The waters around Shetland produce around three quarters of the rope-grown mussels in Scotland and about a third of Scotland’s annual salmon harvest.
But these stocks can be threatened by HABs and one bloom in July 2013 led to a voluntary ban on harvesting from all 20 mussel sites on Shetland, as toxins from some of these algae are absorbed by shellfish, posing a risk to human health.
More recently Grieg Seafood Shetland attributed a poor second quarter this year to a number of algal incidents – including an outbreak of the flagellate known as ‘golden algae’ occurring in the summer and autumn of 2014, which was then followed up by an outbreak of Ceratium in March of this year, leading to losses and poor growth in a number of their salmon sites.
In a bid to give farmers advanced warning of such events, scientists at the Scottish Association for Marine Science (SAMS) in Oban are investigating currents around the islands and yesterday deployed 16 floating ‘drifters’ in the waters to the north of Scotland to track ocean currents, which along with data from satellite images, will help them anticipate when some of these HABs could occur.
The collected data will then be used to validate a model that will more accurately predict the emergence of blooms and will complement a HAB monitoring service currently funded by the Natural Environment Research Council (NERC) and Biotechnology and Biological Research Sciences Council (BBRSC). This will give fish and shellfish growers a reliable early warning system to the emergence of HABs, allowing them to take mitigating actions.
The move has been welcomed by the islands’ aquaculture industry and, David Sandison (pictured above), SSPO's general manger in Shetland, told Fish Farming Expert: “The industry welcomes all new developments that help in our defence against risks to our stocks. There is a need to collaborate with the scientific community to enhance our early warning of harmful algal blooms and this in turn will help us manage options for how to react when any threats are likely.”
Michael Tait, owner and operations director of Sheltand mussels added: “We receive a report on toxin risks in Shetland every week from SAMS and it's very valuable to us. We hope this deployment will support this work and help improve techniques for forecasting risks on an ongoing basis.”
Professor Keith Davidson, SAMS’ principal investigator in Microbial Ecology and Modelling, said: “The security of Shetland’s aquaculture industry is key to ensuring products are safe to eat and to the success and reputation of both Scotland and the wider UK seafood market.
“Science can help build robust early-warning systems that can help reduce the risk of HABs affecting farmed products. The more work we can do in this area, the better prepared we will be.”
A drifter is a floating GPS which can track currents by transmitting their location via satellite every hour. Eight of the 16 drifters have sails to anchor them to the top metre of the water column, while the other eight will have a wire tether and a sea anchor to keep them at about 15m deep, to follow subsurface currents. This allows investigators see how the more wind-driven surface layer moves compared to deeper water.
Plymouth Marine Laboratory and Exeter University are conducting remote sensing as part of this project and the drifters will be released from the Marine Scotland Science vessel, Scotia. The Shetland-based North Atlantic Fisheries College (NAFC) Marine Centre is also contributing to inshore oceanography.
