CONTAINMENT SPECIAL
thermore, detailed study would be required to confirm whether human error was a contribu- tor.
The project characterised a total of 134 in- cidents to a greater or lesser extent, meaning that just two remained uncharacterised.
• The highest number of incidents (26%) were due to holes in the net caused by predation, although this only accounted for the third highest number of escaped fish (12%).
• The second highest number of inci- dents (17%) were due to holes in the net caused by chafe/snag, which resulted in the fourth highest amount of escaped fish (9%).
• The third highest number of incidents (7%) were a result of cage/mooring fail- ure caused by the use of cages that may not have been appropriate for the loca- tion. This accounted for by far the high- est number of escaped fish (23%) and was very much influenced by the January 2005 storm.
• The fourth highest number of incidents (4%) were due to cage/mooring failure caused by the use of moorings that may not have been appropriate for the loca- tion. This was responsible for the second highest number of escaped fish (16%) and, again, was largely related to the January 2005 storm.
• All other immediate causes each ac- counted for 5% or fewer of incidents and included fish handling, net under water, freshwater screen failure, vandalism, helicopter bucket incident, transfer pipe failure, flooding and wellboat collision. Whilst most of these incidents accounted for a relatively small number of escaped fish, two flooding events and one net underwater incident together accounted for 16% of escaped fish, but just 2% of incidents.
A wide range of causes and factors came behind escape incidents, with multiple factors often coming together to create the incident. Therefore, there is no single remedy that will immediately reduce escape incidents in Scot- tish finfish farming; instead it is necessary to consider a range of issues across the sea wa- ter and freshwater environments. These need to focus on salmon and rainbow trout and include consideration of issues as diverse as cage and mooring specification, net design, equipment installation and maintenance, operational issues, fish transfer operations, predator protection, flooding and vandalism – the majority of which have a human error and/or training element to them. Nevertheless, four underlying causes ac- counted for 54% of incidents and 60% of es- caped fish, while all the other causes each ac- counted for two per cent or less. The authors concluded that attention should be prioritised on the following:
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A WIDE RANGE OF CAUSES CREATED ESCAPE INCIDENTS
• Hole in net incidents caused by preda- tion.
• Hole in net incidents caused by chafe/ snag.
• Cage failures from the use of cages inappropriate to the location. • Mooring failures from the use of moor- ings inappropriate to the location.
However, they also pointed out that, as cage and mooring failure has been less evident in recent years, greater attention should be given to holes in nets.
The authors also recommended that more accurate and detailed information on the reporting of escapes in Scottish finfish farming is obtained to allow a greater understanding of the causes of escape incidents.
TOP: TOTAL SCOTTISH ESCAPES PER YEAR
ABOVE: PROPORTION OF ESCAPES PER YEAR BY SPECIES
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ALL GRAPHS IN THIS SECTION COURTESY OF THISTLE ENVIRONMENTAL PARTNERSHIP
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