Dive Dry with Dr. Bill

054: Fish That Fly...

During August visitors to our island are often fascinated by our flying fish. Nearly 500 years ago sailors on Magellan's first voyage around the world reported their unusual behavior, and I'm sure the Gabrielinos saw many as they crossed the Channel to trade their steatite pots with mainland tribes. Even the dinosaurs may have observed flying fish as fossil remains are known from the Lower Triassic in Madagascar!

Flying fish frequent the surface waters of tropical and subtropical seas. There may be 50 to 100 different species. Their biology and ecology are not well-known. The California flying fish is seen most often here, but there are other species including the sharpchin flying fish.

Flying fish are all pelagic or open water fish. They swim in the upper 1-2 meters of the water column, so surface water temperature is important in their distribution. Being a warm water species, they enter our area in late spring and leave in the fall, and are seldom seen north of Point Conception.

Ours is one of the world's largest species, officially measuring 19" long and weighing 1 1/4 pounds although our local boat crew reports larger individuals. The streamlined body is covered with large scales and a layer of mucous. Flying fish have small mouths because they feed on plankton. The short jaws may have tiny teeth. Large eyes, about the size of a nickel, allow them to see their tiny prey and are unusual in that they are adapted to see both underwater and above water (wish mine could see clearly in either environment)!

Living near the surface, flying fish are more vulnerable to predators. Like many fish, their back is blue and the belly is silver in color, which helps to camouflage them. When searched for by birds from above, the dark backs blend in with the dark water while a fish or a sea lion approaching from below sees the silver belly against the bright sky.

Flying fish reportedly swim at speeds of 15-40 mph. Predators like tuna, bonito and broadbill swim faster (40-60 mph) so flying fish evolved another means to escape them. These fish are well-suited for flight or, more appropriately, gliding. The pectoral and pelvic fins serve as their "wings." These fins are greatly elongated and ribbed with flexible fin rays to give them added strength. The fish lack muscles to move them up and down so they are held out from the body like a glider's wings.

Their lateral line along the side of the body warns them of approaching predators. At the first sign of danger, the fish swims very fast using rapid strokes (up to 50/sec) of their modified and enlarged tail (caudal) fin, accelerating them into the air. They approach the surface at a slight angle and extend the pectoral and pelvic fins. Flight is traumatic because the fish is scared and they expend large amounts of energy trying to escape. When they return to the water, they are believed to "sound," or go to deep waters to rest.

Air speed may exceed 20 mph. As the fish drops back to the surface, it may dip its tail fin into the water and accelerate back into the air. This process ("dipping") may be repeated 6-7 times. Flight may be as brief as a few seconds for a single glide or up to 45 seconds covering distances of 50 to 1,200 feet.

During daylight, flying fish remain out at sea but in the late afternoon begin to move inshore where they congregate. Here, near the kelp beds, they may feed or lay their eggs. When day breaks, they return to the open waters. Like other baitfish, the large schools they often swim in is another form of protection from predators.

Flying fish are believed to spawn at the surface when they come inshore at night. The eggs would sink to the bottom if released in the open ocean. Instead the eggs have sticky filaments on them which are believed to attach to the giant kelp and other objects. They may even attach to one another forming large strings of eggs. The number and arrangement of these filaments differs from species to species and some can only be distinguished this way. Each female releases about 500 eggs, each less than 0.1 inch in diameter, which hatch in about 2 weeks. The young may appear quite different from the adults.

Flying fish have a strong tasting, oily flesh and many small bones. However, they are fished for food throughout the tropics. In the Phillipines they are a topping on pizzas (Hey, Antonio's... one flying fish pizza to go?). They are a major food staple on many Caribbean islands. The Japanese use the bright orange eggs in a form of sushi known as tobiko and in surimi (fish meat paste) while in Sri Lanka they are vacuum packed in chili and tomato sauce!

In the United States the flying fish is a commercial species primarily of historic interest. They are used primarily for marlin or swordfish bait, but the development of artificial lures greatly reduced demand. Commercial fishermen caught these fish in nets set parallel to shore to take advantage of their movement from the open waters to the inshore kelp beds. In Catalina waters this fishery occured between the West End and Long Point.

© 2003 Dr. Bill Bushing. Watch the "Dive Dry with Dr. Bill" underwater videos on Catalina Cable TV channel 49, 10:00 AM and 5:00 PM weekdays.

Image caption: Outstretched pectoral fins of California flying fish; top view showing pectoral, pelvic and caudal (tail)
fins as well as dark upper surface; close-up of caudal or tail fin used for propeling the fish into the air;
close-up of pectoral fin showing ribbing for added strength.

This document maintained by Dr. Bill Bushing.
Material © 2003 Star Thrower Educational Multimedia