Salmon is one of the most popular and nutritious fish consumed around the world. It is well known for its distinctive orange to red color. But is salmon naturally orange or does its color come from artificial means? Here are some quick answers to questions about the natural color of salmon:
– Wild salmon get their orange color from eating krill and shrimp that contain astaxanthin, a natural pigment.
– Farmed salmon are fed astaxanthin or canthaxanthin supplements to achieve an orange color.
– Without supplements, farmed salmon would be gray.
– Sockeye salmon develop their bright red color from eating krill and plankton.
– Chinook, coho, and Atlantic salmon get an orange hue from eating small crustaceans.
– Salmon meat contains the antioxidant carotenoid which contributes to the orange pigment.
So in summary, wild salmon obtain their vibrant orange or red color from natural sources, while farmed salmon need additives to recreate this desired color. The exact hue depends on the salmon species and their diet. But orange is not the natural state for all salmon.
The Natural Coloration of Salmon
Salmon species have different natural coloration based on their diets and environment:
| Salmon Species | Natural Coloration |
|---|---|
| Chinook | Olive green to dark blue backs with silvery sides and white bellies |
| Coho | Dark blue backs and silver sides |
| Sockeye | Bright to deep red bodies |
| Chum | Greenish blue backs with stripes and silver sides |
| Pink | Blue gray backs and silver sides |
| Atlantic | Blue-green backs with silvery sides |
As you can see, natural salmon coloration ranges from gray, silver, green, and blue hues to the iconic red in sockeye salmon. Very few wild salmon are actually orange.
Where does the orange color come from?
Salmon get their varying colors from pigments obtained through their diet. Here are the key factors that contribute to salmon color:
– Astaxanthin – This is a reddish-orange carotenoid pigment found in algae and crustaceans like shrimp, krill, and crayfish. Wild salmon obtain astaxanthin by eating these organisms, which is what gives them a vibrant orange-red color. Sockeye salmon accumulate the most astaxanthin due to their plankton-rich diet.
– Canthaxanthin – Related to astaxanthin, this carotenoid is fed to farmed salmon to achieve a pinkish-orange hue. Otherwise, farmed salmon would be pale gray.
– Carotenoids – Salmon flesh contains antioxidant compounds like carotenoids that contribute to orange and red coloration. Carotenoids dissolve in salmon fat, intensifying the color.
– Environment – The marine environment salmon inhabit impacts color. Clear, cold waters with appropriate dietary sources of pigments produce the brightest coloration.
So in the wild, the combination of astaxanthin from crustaceans plus carotenoids in their flesh gives salmon like sockeye, chinook, and coho their trademark vibrant orange-red shade.
Why are wild and farmed salmon colored differently?
Wild and farmed salmon develop different coloration due to contrasting diets and environments:
| Wild Salmon | Farmed Salmon |
|---|---|
| Eat astaxanthin-rich organisms like krill, shrimp | Fed plant-based pellets without astaxanthin |
| Swim in oceans and waters with natural pigment sources | Raised in tanks or enclosed pens |
| Attain vibrant orange-red from natural diet | Grey without carotenoid additives |
In the wild, astaxanthin from krill and plankton bioaccumulates up the food chain into salmon flesh, giving them bright coloration. But on fish farms, artificial astaxanthin or canthaxanthin must be added to feed to replicate this effect. Without pigment additives, farmed salmon would be pale and grayish.
Do different salmon species have different colors?
Yes, various salmon species have evolved distinct natural coloration:
– Sockeye salmon – Bright red, they accumulate the most astaxanthin from eating plankton.
– Coho salmon – Silvery blue backs and lighter silver-gray sides.
– Chinook salmon – Blue-green backs with silver sides. Turn redder with age.
– Chum salmon – Greenish blue backs with stripes and silver sides.
– Pink salmon – Blue gray backs and silver sides, no pink despite name.
– Atlantic salmon – Blue-green backs with silvery sides.
So sockeye salmon are the most vibrantly red, while coho and pink salmon tend to be more silver or gray. Yet most species turn orange to some degree from astaxanthin, especially when returning to freshwater to spawn.
Do wild salmon eat crustaceans?
Yes, the main source of carotenoids including astaxanthin for wild salmon are the crustaceans they eat:
– Krill – Tiny cold-water shrimp, a staple food especially for sockeye salmon. Krill contain high levels of astaxanthin pigment which accumulates in salmon flesh.
– Shrimp – An important dietary component. Shrimp hold carotenoids and give salmon their orange color.
– Crayfish – Eaten by juvenile salmon in streams and lakes. Also contain carotenoid pigments.
– Copepods – Tiny crustaceans that sockeye salmon feed on. Rich sources of astaxanthin which colors the salmon.
Salmon feed on crustaceans like these throughout their lifecycle. The carotenoids are stored in fatty tissues and intensify salmon color, especially when returning to spawn. Without these pigment sources in their diet, salmon would lose their prized orange hue.
Do all Pacific salmon turn orange-red?
No, not all Pacific salmon develop a strong orange or red shade:
– Sockeye salmon – The reddest salmon due to astaxanthin, some call them “redfish”.
– Chinook salmon – Tend to be more green-blue, but turn orange-red as they near spawning.
– Coho salmon – Remain mostly silver-gray their whole lives.
– Chum salmon – Lack orange pigment and stay green-blue with tiger stripes.
– Pink salmon – The most silver salmon, they stay blue-gray overall.
So sockeye and spawning chinook turn the reddest. But coho, chum, and pink salmon often maintain more green, blue, silver hues rather than orange or red. Yet nutritional value remains high regardless of color.
When do salmon become orange?
For most wild salmon species, they become the most orange-red when returning to freshwater rivers and streams to spawn:
– Earlier in life while in the ocean, they maintain more silver, gray, green coloration.
– As they migrate back upstream, physiological changes related to spawning kick in.
– Their bodies start metabolizing carotenoids and fatty tissues.
– This releases astaxanthin and other pigments, allowing them to permeate the skin and flesh.
– Spawning salmon become the reddest and most nutrient-rich.
– Eggs or roe become an especially vibrant orange due to pigment deposition.
So salmon tend to turn most orange at the very end of their lives when swimming back to their natal waters to continue the life cycle.
Conclusion
In summary, wild salmon like sockeye and chinook get their natural orange-red color mainly from eating astaxanthin-rich crustaceans like krill and shrimp. This allows carotenoids to accumulate in their flesh over their lifetimes and intensify during the spawning migration upstream. However, farmed salmon raised in pens are deprived of these pigment sources and would be pale gray without nutritional additives like canthaxanthin or artificial astaxanthin. So while both wild and farmed salmon can end up orange, only wild salmon obtain this color naturally from their carotenoid-rich diet in the ocean. The prized orange hue of salmon actually signifies its outstanding nutritional value.