It’s a fact that farmed fish can and do escape. Sometimes these escapes happen because storms rip up and damage the cages, or when predators attack the nets to get at a tasty meal, leaving a hole for the fish to escape through. Sometimes escapes can happen from unexpected incidences – like when a cargo ship hit a rainbow trout farm off Assens, Denmark, releasing 80,000 individuals into the western Baltic Sea. Less dramatically, simple human error may be the cause – as is the more serious issue of negligence. When some 250,000 Atlantic salmon broke out of Cooke Aquaculture's Cypress Island farm into the Pacific in 2017, Cooke initially blamed a combination of currents, unusually high tides, and a solar eclipse for the escape. It later emerged failure to properly clean the pens, poor condition of parts of the infrastructure, and engineering issues were the most likely cause.
Getting a handle on just how many escapees there are is no easy task. Not all countries require aquaculturalists to report escapism. In some cases, aquaculturalists under-report the number of escapees, or simply may not know how many have broken free. Cooke Aquaculture, for example, initially reported some 160,000 salmon escaped from Cypress Island in 2017, but an independent investigation put that number between 243,000 and 263,000. Despite such accounting issues, the number of escapees is large. In the 1990s, between 20% and 40% of Faroe Islands salmon fisher catches consisted of farmed Atlantic salmon. Meanwhile in Europe, over just three years some 8.9 million finfish escaped farms located in just six countries. Regardless of how it happens, for the aquaculturalist escapees come at a cost. Damaged equipment needs to be repaired or replaced. Every individual lost is revenue lost. When gusts of up to 100 mph tore twelve salmon cages off their mooring in Scotland on Christmas day in 2011, they were washed out into the North Sea - along with £3 million worth of fully-grown salmon. Fines may also be issued. In April this year, Cooke Aquaculture reached a settlement with the Washington Department of Ecology for U$322,000. With Cooke Aquaculture being the largest seafood company in the world and bringing in an estimated C$2.4 billion of revenue in 2018 alone, the settlement amount has invariably received some criticism.
Economic impacts on aquaculturalists are easier to measure than impacts escapees the natural world. Nevertheless, it is clear that impacts can - and do - occur…
This story was written for (and can be read in full in) Eco Magazine.