Are farm raised fish unhealthier than their wild caught counterparts?

Question

I like to eat fish on a regular basis, most notably salmon and tuna. Recently, I've been reading about some of the dangers of fish raised on fish farms. Notably, these can include

• Increased level of PCB's
• High levels of antibiotics to combat crowded conditions
• Toxic environment (Often in excrement being flushed out to sea)
• Lower level of Omega-3 fatty acids
• Added dyes and colors to enhance flesh color

Has any of this been proven, or is this just media hype?

Answer 1

• The claim that farmed salmon have more PCBs than wild salmon is true.

  For example, this paper from Science shows that the PCB (and other organic pollutant) concentrations are approximately 8 times higher in farmed than in wild salmon.

• The claim that Omega-3 fatty acids are lower in farmed than wild salmon is false.

According to the USDA, farmed salmon has a higher concentration of Omega-3 fatty acids than wild salmon at 4.2g vs 3.4g for the default 1/2 fillet tested.

• The claim that dyes are added to make salmon pink is true.

This paper describes an assay to measure astaxanthin content, which is one of the dyes added to the feed of farmed salmon.

Astaxanthin is the single most expensive constituent in salmonid fish feed. Even though astaxanthin constitutes less than 20% of the total fish feed costs, control and optimization of the concentration of astaxanthin from feed to fish is of paramount importance for a cost effective salmonid fish production.