Sockeye and King salmon tend to be darker in color.
Coho and the other varieties tend to be pinker.
From all the research I have done, there is such a small difference (very small) in omega-3 content from the red and pink that one should eat for taste preference (and cost).
The sockeye is more expensive, the pink less so.
Remember that the nutritional analysis will vary from fish to fish because it depends on the water temperature, their diet, health, etc....just like our bodies and the chemistry vary from meal to meal and from season to season
Overall, for those concerned about Omega-3 content in, say, canned pink versus canned red .....it's within 10 or so mg.
Thoreau said, 'A man is rich in proportion to the things he can leave alone.'