The use of algae to grow larvae could reduce industry reliance on wild larvae.
Marine scientists in Scotland have developed “designer” algae that could signal a breakthrough in how shellfish larvae are produced for the aquaculture industry.
The Scottish mussel industry currently produces around 8,000 tons a year using wild larvae and is therefore reliant on a successful spawning year. This method is also a limiting factor in the expansion of the industry, which has the potential to become a major part of Scotland’s economy.
6-10 times more efficient than current systems
The scientists at the Oban-based Scottish Association for Marine Science (SAMS) have discovered this new way of farming larvae in a hatchery by feeding them with “designer” algae, which have been selected and cultivated in a laboratory for optimal growth. By feeding the algae a diet of organic carbon and exposing them to varying levels of light, scientists can control the growth, the size and the composition of the algae. Because it is controlled and tailored for use as mussel feed, this system is 6-10 times more efficient than the current production methods used for oyster or other mussel larval species.
This approach could also change how microalgae are produced for the biotechnology industry.
Dr. Joe Penhaul Smith, who developed the process at SAMS, has published his findings in the journals Bioresource Technology Reports (https://doi.org/10.1016/j.biteb.2019.100321) and Aquaculture International (https://doi.org/10.1007/s10499-020-00629-7).
“These algae are not genetically modified in any way but are ‘designer’ in that we can cultivate these species in different ways to control their nutritional profile,” said Dr. Smith. “We are using their natural evolutionary versatility to control how they grow.
“This is rather like comparing a person’s fitness: someone eating anything they could find in the shops, compared to another person following a managed diet, targeted at staying healthy.
“The system we’ve developed will have an initial start-up cost but growing the larvae on the scale required will save the industry money in the long term. I see parallels with the green lip mussel industry in New Zealand, which benefited from a government-built hatchery at the Cawthron Institute in the 1990s which now produces around 30 per cent of the larvae for the industry there.”
The newly developed feed combines ratios of three algal species: Tetraselmis and the diatoms Phaeodactylum and Cyclotella, which have all previously been used in aquaculture feeds.
“Using these techniques is a huge step forward in algae production and shellfish aquaculture,” said Dr. Adam Hughes, a senior lecturer in sustainable aquaculture at SAMS. Making use of these organisms’ natural ability to grow in different ways means we can increase productivity hugely, and that has the potential to dramatically reduce costs to the industry.”
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