Now, to bring all the posts I have done together and figure out a reasonable estimate of the forage fish killed to feed fish farm fish. The global catch of forage fish is about 20Million metric tonnes per year.
There are many sources that say the ratio of fish in fish out for kgs of forage feed to 1 kg of a farm salmon is 5 to 1. You will find it in this document, for example: http://fishfarmnews.blogspot.ca/2016/08/jack-mackerel-fish-farms-buffalo.html.
That post gives you the catch in Chilean Jack Mackerel over the decades until it collapsed. Look at the graph: http://fishfarmnews.blogspot.ca/2016/08/jack-mackerel-fish-farms-buffalo.html. Norwegian fish farm companies did most of the catching, and along with poor management and closely held quotas, this vast resource has been largely destroyed. In the Sea Around Us document, Norway is listed as the country that fished it down. See: http://www.seaaroundus.org/doc/publications/books-and-reports/2016/End_Use_Reconstruction_Report.pdf.
The BC fish farmers claim that the FIFO ratio is less than 1 to 1, meaning more farmed fish out than forage fish in. This is a very deceptive way of talking because it fails to mention that the reason for the ratio is not efficient conversion, but decimation of the forage fish stocks around the globe by fish farms and they having no choice but to turn to vegetable sources for protein and energy.
The Sea Around Us document, 2016, says that reduction fisheries have largely destroyed (or the stocks are poorly managed in) 19 out of the top 20 stocks, including the jack mackerel off Chile, and now, the anchovetta stocks off Peru and Chile.
At a 5kg conversion rate, the huge loss of forage fish is dramatically shown by the following calculation: number of forage fish per kg X 5kg conversion rate X 5 kg salmon growth X average fish farm number of 600,000 fish X 85 farms in a BC-sized industry. For more background, go here: http://fishfarmnews.blogspot.ca/2016/09/post-3-forage-fish-fish-farm-feed-stats.html.
And the numbers are 282 fish killed per fish farm fish,169.5 Million killed fish per farm, and 14.4 billion fish killed to feed all the farms in an industry the size of BC's.
These staggering numbers would prevail today if there were many fish stocks left to plunder, but there aren't and vegetables have been used, and of course, the conversion rate for forage fish necessarily had to come down. Do go to the NOFIMA report, the research arm of fish farms in Norway, and read the section on conversion rates (p27 - 32). It is very convoluted: https://www.nofima.no/filearchive/rapport-53-2011_5.pdf. The other constituents include fish guts and factory waste, chicken feathers, and in some countries excrement. (I asked EWOS feed company six times to confirm they used no excrement, and they failed to respond).
The Sea Around Us document on reduction fisheries is: http://www.seaaroundus.org/doc/publications/books-and-reports/2016/End_Use_Reconstruction_Report.pdf.
In a personal communication from The Sea Around Us, the people who put the best stats together for reduction fisheries from 1950 to 2010 say a rate of 1.7- to 2.4-kg for fish meal and fish oil is most likely. They are the people in the know on this subject. So I simply took the average, or 2.0 kg in, to 1 kg out.
Correcting for this most believable conversion rate, the estimates are still staggering, but less. The calculation is 11.3 forage fish/kg X 2 kg conversion rate X 5 kg of salmon growth before harvest X 600,000 average fish per farm X 85 operating farms in a BC-sized industry.
The revised figures are still staggering, and this is after fish stocks have been decimated: 113 forage fish killed per farmed salmon; 67.8 million forage fish killed to bring one farm to harvest; and 5.76 billion forage fish killed to bring all farms to harvest in a BC-sized industry.
Please note that I will go back and adjust the half dozen posts on this subject on this blog where my preliminary higher figures were used.
To put these figures in context, based on an 85,000 metric tonnes harvest and 1Million metric tonnes harvest per year in Norway, an industry the size of BC's is less than 8.5% of the Norwegian industry. Hard to believe but true. And then there are the Faroes, Scotland, Iceland, Chile, Tasmania, New Zealand, Australia, Nova Scotia, New Brunswick, Newfoundland and Labrador, Denmark, Finland, Russia and... . In other words: trillions of forage fish killed.