Critics still talking crap about farmed salmon poop

The entire BC farmed salmon industry produces about as much poop every year as 409 dairy cows.

That’s it. That’s barely the equivalent of two average-sized BC dairy farms.

This is important because one of the most common criticisms leveled at salmon farms is that they are using the ocean as an “open sewer.” As usual, the risks are vastly blown out of proportion.

Our favourite activist Alexandra Morton likes to say that salmon farmers are one of the only farmers that “don’t have to shovel their manure” and that we should all be very concerned and scared of farmed salmon poop because there’s so much of it and it’s full of “chemicals.”

We hear or read this one at least a few times each week. And it’s true. It’s also true that, as usual, Morton is telling half-truths distorted by her obsession with the scatology of salmon.

So how bad is it really? Well, for one thing, fish poop is a lot more benign than human poop because they eat a way healthier diet than most of us. And for another thing, recent research shows the environmental impacts are hardly noticeable.

 

Old data, old arguments

Before we get to the new data, we have to consider the old, and it’s really old. The tidbits of info you’ve probably heard are almost all certainly based on information published back when the Vancouver Canucks still played in Pacific Coliseum.

Some environmental activists still claim (without providing a source) that a farm of “200,000 fish can produce as much fecal matter per year as a city of 62,000 people.”

Others, quoting even more ancient sources from the 1980s and 1990s, claim that the waste from a farm is equivalent to a city the size of Victoria, BC.

They’re all wrong. Time to catch up to the latest science.

The Hardangerfjord in Norway produces as much farmed salmon as all of BC. Plus it makes a great desktop wallpaper.

Studying the Hardangerfjord

The Hardangerfjord is the second-largest fjord in Norway and possibly the most beautiful. It’s also home to enough salmon farms to produce 70,000 metric tonnes of fish each year. That’s nearly equivalent to the total capacity of all salmon farms in BC.

According to research published just two years ago, all the salmon farms in the Hardangerfjord produce 7,000 tonnes of particulate organic waste (as well as organic phosphorus and nitrogen, included in the 7,000 tonne total); 127 tonnes of dissolved inorganic phosphorus and 770 tonnes of dissolved inorganic nitrogen.

So all the farmed salmon in the Hardangerfjord produce 7,897 tonnes of waste. Considering that the BC industry is very similar to the farms in Hardangerfjord, with very similar fish, feeding practices and almost identical feed, it’s pretty safe to assume that the BC industry produces about the same amount of waste per year as Hardangerfjord.

Fish poop vs human poop vs cow poop

The average human makes about 128 grams of poop each day (more after Taco Tuesdays). That’s 46.72 kilograms per year.

The average dairy cow produces 19.6 tonnes of poop (and urine) per year.

That means all the salmon farms in BC, all around Vancouver Island, produce as much poop as 169,028 people each year, and as much poop as 409 dairy cows. 

We can’t think of another farming industry that produces so much healthy protein with such little waste.

So next time someone tells you that one salmon farm produces as much poop as a city, you can tell them that’s just a load of crap.