We stand behind our statement that that farming 800,000 salmon would produce the same volume of human faeces as 10,000 people in one day.
Tassal's website states that they intend to farm 800,000 fish in Okehampton Bay – read it here.
Our research and calculations were conducted in the following manner:
- Analysis and consultation with authors of peer-review academic papers to determine dry fecal waste amounts from fish and the equivalent figure in humans.
- Expert analysis and cross-referencing of Tassal's numbers against peer-reviewed papers.
- It was determined that those 800,000 live fish (of what Tassal says is an “average weight” in their sustainability report; weigh about 4000 tonnes.
From this information further calculations were made … in three easy steps, just like cooking a salmon [catch it, bake it, squeeze on lemon].
- To grow 4000 tonnes of fish will take 5,400 tonnes of feed. Of the food fed around 20% will come out of the fish as a mixture of solid & liquid waste - in the example of Okehampton Bay, that’s about 920 tonnes.
- A human excretes 87 grams of solids per day, which is 31.75 kilograms a year.
- Divide the 920,000 kilograms of fish poo by 31.755 kilograms per year and you get an annual average 28,971 people’s worth of people poo, per day.
That’s a lot of poo.
So what about the '10,000 people taking a dump' figure used in our TVC?
Well, LGTF took our research to people with decades of practical experience in the Tasmanian salmon industry – and asked them for a thorough fact-check.
They reported back that the amount of annual fish poo would actually be lower for Okehampton Bay, because the local water temperature during the three hottest months of the year would prevent Tassal from being able to leave salmon stocks in the ocean. Which by the way is one of the key reasons that Huon and other past lease holders have decided that Okehampton Bay is NOT a good place to farm salmon.
They also indicated that Tassal's Feed Conversion Rates are not currently as efficient as those being reached in the Northern Hemisphere. Given these less than optimal growing conditions and other factors, our Tassie salmon experts suggested to us that the relative number of human poo-producers was more likely to be in the range of 10,000 people.
View citations & references