[Depurator]

I'm doing a Ph.D. in salmon farming, it's an exciting field for sure. Just to address some common misconceptions:

* The feed used for norwegian salmon is about 70-80% plant based, so the fish is a net producer of marine protein. The majority is soy, and the industry is trying to transition to sustainable feed ingredients such as insects (see Protix) and micro algae for EPA/DHA (See veramaris)

* The farmed salmon does not contain any contaminents over allowed limits and they do frequent tests (see https://sjomatdata.hi.no/#/seafood/1577)

* The indsutry is beginning to transition from traditional net-pen farming to offshore, land-based and into cell-based and plant-based production, thus also getting production closer to market and spread over areas that may be less susceptible to pollution.

[GordonS]

I've done a lot of reading on salmon farming over the past 6 months, as the tech consultantancy I work for has been investigating approaches within the industry, primarily in Norway. I look forward to reading your thesis :)

The feed conversion rates that Norway is achieving are, frankly, incredible. But the thing that troubles me the most is welfare. Sea lice remain a huge problem, and the mechanical and chemical treatments that are used hurt, damage and kill fish. There are also a shocking number of accidents that can kill millions if fish at a time - for example, chemical treatments gone wrong, or pens not deep enough so millions die from overheating. Then there is the welfare of cleaner fish, with reports of mortality rates over 40%.

Outside of Norway, I've seen some absolutely horrible cage conditions, with the netting completely fouled and the water thick with waste, and damaged, dead and malformed fish everywhere.

While there has been a lot of investment in offshore farming technology, the capex costs are huge, and it will still be some time before we see success at scale. It also comes with it's own risks - I think it was perhaps Havfarm that recently had an incident where the whole platform tipped to the side.

I also find the recent investments into land-based farming are troubling. For all the problems, at least with sea-based farming the fish live in part of their natural environment and have some semblance of space.

IIRC, for land-based farming to even be viable, they need something like 5x more biomass per cubic metre than sea-based farms. Thousands of fish are packed into a tiny area, and literally swim round in circles all day and night, never seeing anything other than the thousands of other fish that surround them, and if they're lucky the occasional glimpse of the side of the raceway.

How do you feel about welfare of farmed salmon, and in particular land-based farms?

[Depurator]

Thank you for your thoughful and interesting reply!

First off, you are absolutely correct in fish welfare being a huge issue. I am in no way condoning the current practices that lead to an average of 20% mortalities in the sea phase in norway, and around 5-10% in regions such as tasmania not affected by sea lice.

Cleaner fish is also a worrying issue with very questionable fish health pactices. Fortunately there are stronger regulations being implemented, that will help remedy some of these issues. One trivial example is that farmers are now required to feed the cleaner fish, whereas they were not before.

I agree that you can absolutely see some horribel looking cages and fish with health issues. The industry explanation is that the percentage that is sick will most likely swim toward the surface and thus give the wrong impression. I say, increase the omega 3 from 1% to 3% and imrpove the quality of the smolt we will surely see benefits.

both offshore and land-based have their issues. net-pen is incredibly efficient and beautiful in its simplicity when it works and the locality is optimal. Salmon will be reared at maximum 25kg/m3, but on land they wanna do 50kg+/m3 to be profitable. They wont do more than 100, as you will see decreasing fish health. For comparison tilapia is known to be farmed at 600kg/m3 in some regions.

Land-based farming will be interesting for sure, and a compeltely new set of issues regarding pathogens and Co2, H2S, NH4 problems. I'm sure they will figure it out. Atlantic Sapphire sure has a lot riding on figuring fish health on land out. Not very promising with the big emergency slaughter the other week.

let me know if you wanna have a chat at some point, always intersting to look at the industry with different eyes.

[bjoli]

Are there any viable solutions to the problems with off-shore farming? Last time I checked the ecosystem around you typical Scandinavian salmon farm in the ocean was devestated.

We take extreme care not to flush our own sewers into the sea, yet happily permit salmon farms with the equivalent fertilizing effect of a town of 25000 having all their toilets flush everything out on the shore.

[Depurator]

To compliment Gordons reply, here's a (norwegian) overview of the environmental conditions around the farms: https://www.fiskeridir.no/Akvakultur/Drift-og-tilsyn/Overvaa...

The last years they have hovered around 95% being very good or good. So statistically you are very wrong. But sure there are some localities that have bad conditions, and those should be closed and new localities should be opened for those farmers. Such as offshore localities when the technology is mature. Many smart people are trying to figure that out with strong scientific backing, but the report from havmerden is avaliable to read if you understand norwegian

In norway there are many environmental institutions following the state of the fjords, so I wouldn't be too concerned.

[bjoli]

What I am saying is not that that are not following current regulations. I am saying at the current regulations are too weak, which Naturvernforbundet agrees with.

They are _still_ using hydrogen peroxide to combat lice for example, despite it's effect on shrimp and plankton.

I am all for farming fish, but on land in closed systems.

[GordonS]

There are lots of different approaches being taken to offshore farming, but few have been tried at scale yet.

One of the concepts is closed-containment farming, where the fish are kept in a sealed enclosure. The fish can be kept below the sea lice level, and all waste can be collected. The downsides are cost, failure modes, and welfare (the fish have less area than open-pen near-shore farms, and will never see sunlight, for example).