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Closed Containment

by Roger Cottis - 17:31 on 01 August 2015

During my consultancy work there is a need to gather accurate information, collate the data and present the findings on a map.  This informs where areas of conflict might arise with a development related to whichever species or habitat might be impacted.  The survey data are displayed in a formal report, which highlights the legislation and background related to the subject and creates a discussion culminating in a series of mitigation measures if required.

With marine fish farms it has been acknowledged by government agencies that severe problems can be encountered in the form of pollution that smothers important seabed habitats and the species which rely on those habitats.  This stems from fish faeces and urine to excess food, which contains chemical therapeutants to combat another and ever increasing problem, that of sea lice and wild salmonids.  Sea lice exist naturally and wild fish are often host to a very small number, with which they cope.  However, when up to a million captive fish are exposed to the same parasitic threat they are unable to escape, being confined in open-mesh nets.  Sea lice multiply uncontrollably, especially when water temperatures increase and hosts are readily accessible as is the case with open-net cages.  The effect of such parasitism is for the affected fish to be eaten alive, hence the intervention with large doses of therapeutant chemicals.  It seems that sea lice are becoming resistant to the current treatments, which eventually results in wholesale culling of fish followed by transportation to landfill sites.  Government agencies are trying their best to combat these and other problems with strict controls but all to no avail.  

Because seals naturally predate fish they are attracted to industrial sized fish farms by all of the distress signals emitted by the fish when they register a predator is nearby.  This has the effect of stimulating hungry seals.  This is no fault of the seals, yet they are condemned to die albeit under a government licence.  Similarly when inshore cetaceans, typically porpoise, become attracted, acoustic deterrent devices (ADD’s) are deployed, which to an animal relying on their sonar, will be at the very least painful and possibly disorientating.  Scientists are unable to confirm the efficacy of the ADD’s; I sense there should be a moratorium on their deployment while deleterious impacts on cetaceans are studied properly.

So, having highlighted some of the problems with open-cage marine fish farming it became necessary for me to consider what could be done to mitigate the effects.  Online research found several individual and corporate aquaculturalists designing and utilising closed containers, both in the sea and on land.  The designs are scalable, enabling large units producing high outputs of clean fish, which because they are able to pump water in a stream, fish naturally swim against the current and their flesh confirmation becomes similar to that of wild fish (not so with current marine farmed fish).  The closed design eliminates all of the problems already highlighted and when combined with small scale hydro and solar panel energy further benefits accrue.  If the design is extrapolated to incorporate aquaponics then additional benefits, through recirculating water being pumped to a series of other containers, can produce other species than fish culminating with green vegetables before the same water is reused in the system.

Therefore I suggest government agencies should investigate all aspects of the science related to the current fish farming industry then instigate a programme of phasing-in closed containment facilities to start redressing the damage to our sensitive marine ecology.  Brown field sites could be targeted for new facilities and eventually even more jobs could be created in an ecologically sustainable way, especially when combined produce is enabled from a correctly designed installation.  So, fish and other species plus vegetables from the west coast of Scotland.  This would be a truly imaginative and bold initiative in the spirit of entrepreneurship associated with previous generations of imaginative and creative Scots.   

Comment from Niall McKillop at 20:21 on 02 August 2015.
Very succinctly and comprehensively put Roger. I'd like to add that I feel a small watershed levy should be raised from every renewables project, and retrospectively where appropriate, to be used to return to wild fish health what has already been damaged and also perhaps to assist in moving to closed containment. It would scarcely be noticed after a couple of years but would be a serious contribution in terms of cleaning things up.

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