Shape of to come
Banning the use of acoustic deterrents could leave marine mammals worse off
Prime Minister Boris Johnson recently announced a new energy strategy which he described as a green industrial revolution. Included in the plans is the ambition to quadruple offshore wind power to 40GW by 2030. This should provide enough energy to power every home in the UK, but meeting the target will require up to 6,000 offshore windmills.
The installation process for each windmill involves using a specialist hydraulic ram to set a “monopile” – a steel tube of about 6m diameter – into the seabed. Once set, the windmill is attached to the monopile. I mention all this because the process of ramming the foundation of the windmill into the seabed is an extremely noisy process which could disturb cetaceans, such as dolphins, porpoises and whales.
To ensure that these creatures stay well out of harm’s way, the construction companies place acoustic deterrent devices (ADDs) around the area. In Germany, the use of these devices is mandatory.
ADDs are also used in a variety of other industries, including the fishing and aquaculture sectors. Under EU rules, ADDs, or “pingers”, are mandatory on fishing vessels of more than 12m in length, but these represent only two per cent of all boats using static nets.
According to Whale and Dolphin Conservation, more than 1,000 porpoises die every year caught up in such nets, yet when Cornish fishermen applied for a licence to use pingers to help reduce this by-catch, the licence was refused on the grounds that the pingers could disturb a protected species by putting noise into the environment.
Under current legislation, which does slightly vary between England and Scotland, it is illegal to deliberately or recklessly disturb, injure, kill or capture whales, dolphins and porpoises. It seems that the regulators would rather the porpoises died in the nets than be deterred from getting near them.
How the legislation is interpretated has led to all sorts of confusion.
The Coastal Communities Network (CCN) in Scotland is demanding that ADDs on salmon farms are banned. They say that many farms don’t use them, and that this shows farms can operate without them. They seem to ignore the fact that many farms don’t have a local seal population, which is why they don’t need to use ADDs.
In the future, ADDs will, however, have to be licensed by Marine Scotland and farms will need to prove that they don’t harm the protected species.
Like salmon farming itself, ADDs are continuing to evolve. Dolphins, porpoises and toothed whales use high or very high frequencies to communicate and hence to hear, so the new generation ADDs operate between these high frequencies and the very low frequencies used by baleen whales. They are also much more targeted, with thermal sensors that switch on the deterrent when a heat source, such as a seal, approaches a farm.
The concept of different animals operating on different frequencies will be familiar to dog owners, whose pets can hear whistles that are silent to the human ear.
In much the same way, the “Mosquito” deterrent has been deployed to
Common seals Offshore wind farm
stop large groups of teenagers congregating in town centres. The noise emitted is undetected by most of the public but young people have more sensitive hearing. They find the noise objectionable and move away within minutes.
This is how ADDs on salmon farms work, yet critics consider their use reckless. They claim that the noise is like sonic torture but as with teenagers, the whales, dolphins and porpoises are unlikely to move towards noise sources they find unpleasant.
Of course, people in the salmon farming industry would rather not use ADDs. They did not like shooting seals, either. But no-one has come up with a solution should a seal manage to get into a pen with the fish. Critics say farmers should use double layers of reinforced nets but, not surprisingly, some seals still overcome these obstacles.
Salmon companies regularly post images of dolphins, porpoises and whales swimming in the vicinity of salmon pens. They are welcome visitors and there is never any intention of disturbing them. There has been a prosecution for such harassment, but by someone on a jet ski.
Determining what is disturbance can be difficult. Some of the most outspoken critics are the owners of whale watching tours but it could be said that such activities are also a form of harassment.
Like all boats and ships which emit extensive noise, tourist boats could easily disturb protected animals as much as an ADD on a salmon farm.
The underlying problem is that ADDs are not the primary target of lobby groups such as CCN. They simply don’t like salmon farming in their area and will use any means of attack to ensure farms are moved. The word “nimby” springs to mind.
It will be interesting to see whether CCN, which is not exclusively based in the west, will campaign against Boris’s new green industrial revolution.
Wind farms are just as likely to be sited around Scotland as they are in the rest of the UK and they will all need to be protected by ADDs.
Some more discerning consumers o�en complain that salmon is not as pink as it used to be. They probably have a point. An intriguing research project by Nofima, the Norwegian Ins�tute of Food, Fisheries and Aquaculture Research, hopes to show why salmon fillets are becoming paler even though fish are receiving more dye in their feed.
Nofima says the red colour of salmon meat comes from the pigment astaxanthin, found in several types of fish and shellfish, which is added to the feed.
According to the Fisheries and Aquaculture Industry’s research funding body (FHF), the pigment level in salmon fillets has decreased in recent years, with some fish farmers this year repor�ng some of the lowest pigment levels yet recorded.
Both the feed and the stress levels of the salmon have changed over �me. Farmed salmon now eat feed with a lower propor�on of marine raw materials. This can increase the fish’s need for the pigment astaxanthin, which is also an an�oxidant. The researchers are planning to inves�gate how the composi�on of feed affects the colour of the fillet, along with the salmon’s ability to handle stressful processes such as delousing. Kris�an Prytz, head of aquaculture and processing
at FHF, hopes the project will provide be�er knowledge allowing the industry to develop and use modern ingredients in feed that do not affect pigmenta�on.
The work will build on an earlier FHF project where researchers from Nofima and the Norwegian University of Science and Technology (NTNU) inves�gated the connec�on between the feed’s content of marine raw materials and the colour of the salmon fillet.
It seems that where there is less marine raw material in the feed, there are also fewer fats, such as phospholipid, which can affect how pigment is u�lized by the salmon.
“We found a lot of interest in the FHF project, but we were also le� with new ques�ons which we need answers,” said senior Nofima researcher Trine Ytrestøyl.
In summary, the research shows that colouring can be greatly affected when changing the feed composi�on:
Other points made by Nofima show:
• The amount of phospholipid in the feed affected the salmon’s ability to digest astaxanthin and fat. Too low a level of phospholipid in the feed caused the salmon to grow more slowly.
• With much less fishmeal in the feed, the appe�te of the salmon decreases, and fat was deposited in the intes�ne.
• When phospholipid was added to feed low in fish meal, it normalised salmon diges�bility and growth.
• Salmon that received feed supplemented with marine phospholipid in the feed deposited less fat in the intes�ne than salmon that received the plant-based phospholipid soy lecithin in the feed. • Although pigment diges�bility was similar in the two groups, the salmon that received soya lecithin had the reddest fillets.