DIVE DRY WITH DR. BILL #753: RED, WHITE AND BLUE
This week's column will focus on the red, white and blue but I'm not talking about my country's flag. It is extremely rare to see that underwater, and when I do it is usually because I'm near the surface and can see the flagpole at our dive park. On rare occasion I have seen it underwater, and thought that was disrespectful but was told it is not as long as the flag is flying free.
The red, white and blue I'm referring to today would be visible if you frequented fish markets on your surface intervals. There you would undoubtedly see fish filets displaying those colors. Anglers and spearos would also be aware of this morphological diversity. For example, tuna flesh is often reddish in color (and salmon flesh more pink), halibut steaks are white and fresh lingcod filets are blue before cooking.
This topic was brought to mind by my mainland dive friend Konrad Fry who posted an article on Facebook about it written by Alastair Bland which was featured on NPR public radio. I do eat my fine finned friends on occasion (mostly salmon) but stopped hunting and spearing back in the mid-1970s. Despite that I have no objection to those who do so legally.
My dive buddy, Captain Andrea Bill, loves sushi and sashimi, especially when prepared with the bright red flesh of yellowfin tuna. These fish are highly active predators and speed demons. Their red flesh is related to this. No, it isn't due to their prey. It is caused by the protein myoglobin in their muscle tissue.
Other fast swimming fish including swordfish, marlin and mako sharks and marine mammals have reddish muscle tissue due to this protein. Deep diving marine mammals such as seals and sea lions as well as humans and other terrestrial mammals also exhibit this. Like the hemoglobin in our blood, myoglobin binds to and stores oxygen and high levels of it are necessary to permit continued high speed in pursuit of munchies. The protein also gives the flesh the red color. It is also responsible for the brownish flesh that is sometimes discarded.
I don't eat much tuna or swordfish due to the elevated mercury levels in the flesh. I am red-blooded but my preference in fish flesh is usually pink, especially the smoked salmon sandwich at The Lobster Trap. Salmon meat is often pinkish in color (and sometimes red). Dr. Milton Love explains this due to two factors. First, salmon often eat a lot of krill which contains carotenoid pigments that are incorporated into its flesh. They have a special gene that allows these pigments to dominate the appearance of the filets and steaks. However pink is only found on our flag when it has faded in the sun.
Most fish eaters are familiar with the white flesh of species like the tasty halibut. These flatfish are bottom dwellers that rest on the sand or mud, often partially buried. They are ambush predators so capturing prey consists of rapid attacks followed by long sedentary periods lying on the bottom. Only rarely do they need to swim any distance. Therefore they do not need the same level of oxygen storage in their tissues and the flesh is white.
So how do we get the "blues." Spearos and anglers often take lingcod, which tend to be in colder, often deeper waters along our coast. Dr. Love writes that the blue color is believed to be a result of a bile pigment, biliverdin. How this molecule enters the blood and flesh is still a mystery. The lingcod's relatives such as the rock and kelp greenlings also exhibit blue flesh, as does the cabezon.
So if you want to be super patriotic on the Fourth of July, cook up some tuna, halibut and lingcod on your barbie!
© 2018 Dr. Bill Bushing. For the entire archived set of over 750 "Dive Dry" columns, visit my website Star Thrower Educational Multimedia (S.T.E.M.) Home Page
Image caption: Red yellowtail tuna (ahi) steak and orange salmon meat; white halibut steak and blue lingcod filet.
This week's column will focus on the red, white and blue but I'm not talking about my country's flag. It is extremely rare to see that underwater, and when I do it is usually because I'm near the surface and can see the flagpole at our dive park. On rare occasion I have seen it underwater, and thought that was disrespectful but was told it is not as long as the flag is flying free.
The red, white and blue I'm referring to today would be visible if you frequented fish markets on your surface intervals. There you would undoubtedly see fish filets displaying those colors. Anglers and spearos would also be aware of this morphological diversity. For example, tuna flesh is often reddish in color (and salmon flesh more pink), halibut steaks are white and fresh lingcod filets are blue before cooking.
This topic was brought to mind by my mainland dive friend Konrad Fry who posted an article on Facebook about it written by Alastair Bland which was featured on NPR public radio. I do eat my fine finned friends on occasion (mostly salmon) but stopped hunting and spearing back in the mid-1970s. Despite that I have no objection to those who do so legally.
My dive buddy, Captain Andrea Bill, loves sushi and sashimi, especially when prepared with the bright red flesh of yellowfin tuna. These fish are highly active predators and speed demons. Their red flesh is related to this. No, it isn't due to their prey. It is caused by the protein myoglobin in their muscle tissue.
Other fast swimming fish including swordfish, marlin and mako sharks and marine mammals have reddish muscle tissue due to this protein. Deep diving marine mammals such as seals and sea lions as well as humans and other terrestrial mammals also exhibit this. Like the hemoglobin in our blood, myoglobin binds to and stores oxygen and high levels of it are necessary to permit continued high speed in pursuit of munchies. The protein also gives the flesh the red color. It is also responsible for the brownish flesh that is sometimes discarded.
I don't eat much tuna or swordfish due to the elevated mercury levels in the flesh. I am red-blooded but my preference in fish flesh is usually pink, especially the smoked salmon sandwich at The Lobster Trap. Salmon meat is often pinkish in color (and sometimes red). Dr. Milton Love explains this due to two factors. First, salmon often eat a lot of krill which contains carotenoid pigments that are incorporated into its flesh. They have a special gene that allows these pigments to dominate the appearance of the filets and steaks. However pink is only found on our flag when it has faded in the sun.
Most fish eaters are familiar with the white flesh of species like the tasty halibut. These flatfish are bottom dwellers that rest on the sand or mud, often partially buried. They are ambush predators so capturing prey consists of rapid attacks followed by long sedentary periods lying on the bottom. Only rarely do they need to swim any distance. Therefore they do not need the same level of oxygen storage in their tissues and the flesh is white.
So how do we get the "blues." Spearos and anglers often take lingcod, which tend to be in colder, often deeper waters along our coast. Dr. Love writes that the blue color is believed to be a result of a bile pigment, biliverdin. How this molecule enters the blood and flesh is still a mystery. The lingcod's relatives such as the rock and kelp greenlings also exhibit blue flesh, as does the cabezon.
So if you want to be super patriotic on the Fourth of July, cook up some tuna, halibut and lingcod on your barbie!
© 2018 Dr. Bill Bushing. For the entire archived set of over 750 "Dive Dry" columns, visit my website Star Thrower Educational Multimedia (S.T.E.M.) Home Page
Image caption: Red yellowtail tuna (ahi) steak and orange salmon meat; white halibut steak and blue lingcod filet.
