How sustainable is the production of fish by aquaculture?
Take salmon for instance.
Farmed salmon is now Scotland's largest single food export, outstripping beef, diary produce and wild-caught fish. Worth nearly £540m in 2010 to the producers, its global retail value is estimated to be well over £1bn, according to these figures from the SSPO. The industry and Scottish government hope to increase production by 50% by 2020, particularly to target new markets such as China.
Here are some problems though...
According to the Scottish Salmon Producers Organisation (SSPO), the main industry body, there are disclosed consistent reports of significant sea lice problems. In west Shetland last February, sea lice infestation rates are 584% higher than the recommended levels and on average more than 250% higher.
What is sea lice?
The sea louse (plural sea lice) is a copepod within the order Siphonostomatoida, family Caligidae. There are around 559 species in 37 genera, including approximately 162 Lepeophtheirus and 268 Caligus species. Sea lice are marine ectoparasites (external parasites) that feed on the mucus, epidermal tissue, and blood of host marine fish.
The SSPO admits that sea lice infestation cost the industry £30m in 2010, against sales of £400m. The SSPO denies the situation in Scotland is out of control, but it told industry experts in 2010 that "sea lice represent the greatest single threat to the health and welfare of farmed salmon and the sustainability of salmon production."
The data from Sepa, the first time that farm-by-farm chemical useage figures have been seen, shows that between 2008 and 2011, these chemicals were used 2,756 times with the overall weight of the five treatments used rising from 188kg to 395kg.
Don Staniford, a campaigner who was given the chemicals data by Sepa, and who has previously been deported from Canada for his activities against its fish-farming industry, said he believed the increase breached the UK's legal duties to protect the marine environment.
"Instead of reducing chemical use, Sepa has shamefully sanctioned a doubling in the use of toxic chemicals which are known to kill lobsters and other shellfish," he said.
The chemicals used are highly toxic to marine species such as lobster, prawns and other fish. The salmon industry is expected to keep their use under strict control but has seen significant problems in Norway with the emergence of "superlice" that are highly resistant to normal treatments.
Some are organophosphates, which attack the nervous system of the sea lice, while teflubenzuron interferes with their ability to grow their shells. Marine scientists have shown that the chemical is extremely threatening to young lobsters, crabs and prawns.
Ecologists and campaigners argue there is compelling evidence some fish farms are failing to use chemicals safely. Sepa disclosed last week that while a large majority were satisfactory or excellent, 54 fish farms were rated as "poor" in 2011 – mostly for having too high chemical residues on the seabed, an increase on the 51 found to be poor or very poor in 2010.
In Stirling, research is carried out to solve this problem with a more holistic approach. Recent developments in sequencing, mucosal immunity, protein mass spectrometry and vaccine technology are used in order to develop a novel vaccine capable of providing substantive, eco-friendly control of sea lice infections in farmed salmon. Vaccines provide a means to tackle a major constraint to the sustainability of protein production, as well as helping to protect rural jobs, the marine environment and wild salmon stocks.
Chemicals to control salmon parasites
Scottish fish farmers use record amounts of parasite pesticides
Development of a novel sea louse vaccine: an environmentally friendly tool for increasing sustainability of protein production in UK salmon aquaculture