TTW editor Chris Leibbrandt reveals some of his early career in horticulture and discusses an interesting link with salmon farming, and with a little help from our fishy friends.
A long time ago, in a galaxy far, far away… I used to be a professional horticulturalist, groundsman and greenhouse manager, with a staff of around 50 people. I used to grow around three million plants a year in some four hectares of glass. Not big by Dutch standards but still plenty to keep me occupied.
You might be wondering what on earth this has got to do with fishing, and the connection may seem tenuous, but just indulge me for a few paragraphs and all, I trust, will become clear. When I began to review and upgrade an old plant nursery, I decided to employ an ethos that had interested me for a number of years (more of this later), namely biological control to control the usual problems of pests and diseases. Pests and diseases in glasshouses are generally the result in stocking densities that are too high, the same as it is in any intensive farming of plants, livestock and fish. In those days, biological control was a bit cutting edge because most greenhouse pests and diseases were controlled with chemicals, herbicides and pesticides with little thought to the residual effects on the environment.
So what is biological control? Basically it’s the use of any creatures (sometimes viruses and fungi) to create a symbiotic equilibrium with the pests and diseases. For example, anyone who has been in a greenhouse and been covered in a cloud of tiny whiteflies, they’re a real pest. Luckily for us, there’s a tiny wasp, Encarsia formosa, (around two millimetres long) that just loves to eat them in a gruesome display of motherhood. They inject their eggs into the whitefly and the babies eat their way out. Luckily, this is all in a tiny world where you can ignore the alarming terror of natural selection and survival. There are also beetles,
Cryptolaemus montrouzieri, that like to eat aphids and mealy bugs. The downside is that the pests are never fully eradicated, the predators understanding that an equilibrium is essential, otherwise they’d exterminate their own food source. What happens is the two colonies come to a balance that is manageable enough that you can forget it. It runs itself, with nature working out the logistics.
This is similar to predators like walleye, zander, pike or muskies in a fishery. When left alone they work out their own levels, something as a pike angler I was very interested in. I was collaborating with a famous pike angler and Cambridge Professor, Dr Barrie Rickards, to produce a document that set out the case for keeping, and even stocking, pike into waters to improve overall fishery biodiversity and health. The two worlds of fishing and horticulture appeared to me to be parallel and complementary. They would both benefit from a biologically based solution led by science rather than anecdotes and prejudice.
Okay, so what made me think back on those interesting and formative years was an article I read a couple of years ago about biological control of sea lice in salmon farms. The benefits to every link of the food chain, right through to recreational sport fishing, were obvious. Last week saw the results of implementing the research and the near miraculous results that letting nature do the business had produced.
About four years ago, four organisations, Swansea University’s Centre for Sustainable Aquatic Research (CSAR), Marine Harvest (Scotland) Ltd, RAS Aquaculture Research Ltd and The Cleaner Fish Company Ltd, got together to work on the sea lice problems in salmon farms.
Salmon lice are crustacean parasites that can reduce health, growth and survival of salmon. Sea lice infestation also compromises fish welfare and its treatment costs the European salmon industry around €300m every year.
Companies across the salmon industry have been working to reduce the severity of lice outbreaks using appropriate management. Despite the use of various medicines the lice have become increasingly resistant. The disease is fast becoming the primary threat to salmon farming, all at a time when demand for Atlantic salmon is increasing.
Looking at biological control as an effective alternative to medicines, use of ‘cleaner fish’ in the salmon pens has been investigated. There are a number of cleaner fish species that naturally develop a symbiotic relationship by removing and eating parasites, such as sea lice, from their host. One of them is the ugly little lumpfish, or lumpsucker (Cyclopterus lumpus), its use, particularly in the cold months during winter and spring, has received particular attention.
The project at CSAR brought industry and academic personnel together to investigate the potential of lumpfish for use as cleaner fish, and to develop methods of sustainable juvenile lumpfish production for use in commercial salmon farming.
Starting with around 8,000 juvenile lumpfish in 2014, CSAR production in 2015 reached over 1.2 million larvae for a number of Scottish sites that were deployed once they got to 10g to 15g. Lumpfish research at CSAR has led to more efficient and sustainable production methods, including lumpfish genetics, improved hatch rates and survival, and optimised health and growth.
The Scottish Salmon Producers’ Organisation (SSPO) shows that over the past two years, use of medicinal treatments has dropped from 71 per cent of total fish health management costs to 28 per cent.
The use of cleaner fish, not only lumpfish, but also wrasse, has produced positive results, according to the SSPO’s Fish Health Management Annual Report. By the end of 2016, sea lice management was the best it had been for some years.
Scott Landsburgh, chief executive of SSPO, said: “The investment in cleaner fish like wrasse and lumpfish, as well as the new machinery to remove lice, is proving successful and looks encouraging for the future.
“We will always need responsible access to medicines as part of a multi-faceted strategy, but this has been a significant turnaround for the salmon farmers. Wrasse and lumpfish are becoming a key part of fish farming and the potential to farm wrasse for the salmon farming sector is an exciting opportunity for further investment and jobs in Scotland.”
Biological control looks to continue to be a major part of the battle against sea lice, with wrasse and lumpfish now used throughout the industry in Scotland, with investment of around £14 million in the farming of both species.
It seems to me that a lot of the answers have always been with us, we just need to have open minds to recognise them and trust the natural world to provide them.