Lingcod are large, mottled fish found in the Pacific Ocean, particularly along the west coast of North America from Alaska to Baja California. These predatory fish can grow significantly, reaching lengths of up to five feet and weights over 80 pounds. While typically exhibiting colors like dark gray, brown, or greenish on their backs, some lingcod display an unexpected and vibrant electric blue or turquoise coloration in their flesh.
The Chemical Explanation
The striking blue color observed in some lingcod flesh is primarily attributed to a bile pigment called biliverdin. Biliverdin is a natural byproduct formed during the breakdown of heme, a component of hemoglobin found in red blood cells. When red blood cells complete their lifespan or are broken down, the heme portion is converted into biliverdin. This bluish-green pigment normally undergoes further conversion into bilirubin, which is yellowish. However, in blue lingcod, biliverdin accumulates and circulates through their lymphatic system, ultimately suffusing the muscle and connective tissues, leading to the distinct blue or turquoise coloration. The presence of biliverdin is also responsible for the green color seen in healing bruises in humans.
While the role of biliverdin is well-understood, the precise mechanisms by which it accumulates in such high concentrations in the muscle tissue of some lingcod, or why only certain individuals are affected, remain areas of ongoing scientific inquiry. Scientists hypothesize that factors like diet, genetics, or even liver function might influence biliverdin levels and its deposition in the flesh. Studies have also suggested that biliverdin levels can be elevated in other fish species during periods of starvation.
Variations in Color
Not all lingcod exhibit the blue coloration; their flesh can range from the more common white to shades of green or turquoise. The occurrence of blue-fleshed lingcod varies by region, with reported incidences ranging from 4% to 25% of the total population, indicating that it is a minority trait.
Research indicates that the probability of having blue flesh is highest in female lingcod, smaller individuals, and those caught in shallower waters. For instance, about 80% of blue lingcod observed in some studies were female. While diet is often speculated to play a role, studies have not definitively linked specific food items to the blue color. Some findings suggest that blue-fleshed fish may have lower concentrations of certain fatty acids, potentially indicating differences in energy storage or nutritional stress. The blue coloration is also observed in other members of the greenling family and some sculpins.
Eating Blue Lingcod
Blue lingcod is entirely safe and healthy to consume. Despite its unusual raw appearance, the blue color is not indicative of disease, contamination, or any adverse quality. When cooked, the blue pigment typically disappears, and the flesh transforms to a normal white, flaky consistency.
The cooked flesh of blue lingcod has a mild flavor and a firm, flaky texture, similar to other lingcod or Pacific cod. This makes blue lingcod a versatile option for various cooking methods, including baking, searing, or grilling.