Ocean Fish Farms Won’t Save Wild Fish & Can Easily Destroy Them
by Matthew McDermott, New York, NY 
on 12.15.08
Sea lice photo: Watershed Watch
A couple months ago we ran a short animation on how sea lice from fish farms can reduce wild salmon populations. Now a new study in shows, in a broader context, why and how ocean fish farms can hurt wild fish populations.
Done by Prof. Neil Frazer of the University of Hawaii at Manoa, the basic premise is that the higher density of fish in the farms promotes infection, and that infection lowers the fitness of surrounding fish. For the wild fish this means:
Lower Fitness Doesn’t Benefit Fish Any More Than Humans
...more difficulty finding food and escaping predators, causing higher death rates. But farmed fish are not only fed, they are also protected from predators by their cage, so infected farm fish live on, shedding pathogen into the water. The higher levels of pathogen in the water cause the death rates of wild fish to rise. (Science Codex)
Even if Fish Farms Are Medicated, the Effect Isn’t Good
After describing how sea lice attack salmon the report sums up the impact on ocean fish farms:
...even if lice levels on farm fish are controlled by medication, local wild fish still decline. Also, there is a critical stocking level of farmed fish. If a sea-cage system is stocked above the critical level, local wild fish decline to extinction. Long story short — growing farm fish in sea cages can't save wild fish, but it can easily destroy them.
via: Science Codex
Ocean Fish Farming
Animation Shows How Sea Lice From Fish Farms Can Reduce Wild Salmon Population
Deep Sea Fish Farm: Deep Trouble?
Coastal Fish Farms Endanger Wild Fish?
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I was watching a Discovery Channel show about solutions to fish farming problems. They mentioned putting pens much farther out in the ocean in strong currents so the sea lice larva would be swept away. I believe they said tht there weren't any other species living in the area they were testing so the lice starved to death before the currents brought them to more fish. I've also seen plans to put muscle and kelp farms around fish farms to treat the sewage from the fish. I wonder how muscles grown exclusively on salmon poo taste? I'm not a vegetarian yet, but I'm getting there. I'd be thrilled if there was a native North American herbivorous fish (like talapia) that could be farmed without worrying about introducing invasive species.