The Sailfish is one of the most instantly recognizable creatures in the ocean. With its distinctive, sail-like dorsal fin, it’s a readily identifiable fish and is the one species of billfish that isn’t easily confused with any other. Because it’s a billfish, it also has a long, sword-like bill that it uses when hunting.
The scientific name for the Sailfish is Istiophorus platypterus, though some scientists consider Sailfish in the Pacific and Atlantic Oceans to be two different species.
They are sometimes called Ocean Gars and Bayonetfish, but the coolest name is the Japanese one: nishibashou or nishibashoukajiki.
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Most everyone can recognize a Sailfish when they see them, as they have a distinctive, prominent dorsal fin that resembles a sail. But other aspects separate them from other billfish.
Within the species, as in all the other billfish species, exists sexual dimorphism, and the females grow larger than the males. This size disparity increases the number of eggs a female Sailfish can carry.
Females can grow to ten feet long, while males can be as small as 5.6 feet long. The largest Sailfish on record was more than 11 feet long.
The Sailfish has a dark blue dorsal side (the top of the fish) and a white underbelly (ventral side) with brown spots. Most of the fins are dark blue, though the anal fins can often be white.
But the big thing is the Sailfish’s dorsal fin. It runs almost the entire length of its body and stands taller than the fish’s body is wide.
It’s taller toward the middle and has black spots on it, though they are most heavily concentrated toward the back of the fin.
Because it’s a billfish, the Sailfish has a long, sword-like upper jaw twice as long as its similarly pointed lower jaw. Together with the dorsal fin, this constitutes the Sailfish’s iconic appearance.
Finally, the Sailfish has a series of whitish, vertical stripes running the length of its body on both sides. These stripes are almost as pronounced as the same kind of stripes on the striped marlin.
Sailfish live relatively short lives compared to other billfish, living an average of about four years. They begin life when they hatch from eggs and are less than a centimeter long.
But they don’t stay so small for long at all, reaching a length of more than four feet within their first six months of life.
As larvae, the Sailfish don’t have the long upper jaw but instead have several spines on their head, but by the time the larval Sailfish has grown to a quarter of an inch long, the upper jaw begins to emerge.
They spawn in warmer months off the coasts of North America and West Africa. Oceanographers have recorded them spawning year-round in some cases in the Atlantic Ocean.
Since the Sailfish reproduces using external fertilization, the female releases eggs (more than four million at a time), after which the male releases sperm into the water to fertilize them.
Sailfish can dive deep. The deepest recorded dive of a Sailfish is 464 meters (almost 1,500 feet), but like other billfish, they prefer shallower waters.
They spend most of their time above the thermocline, which separates warmer ocean water from the colder waters that occur at greater depths.
Sailfish prefer the upper waters of the open ocean (epipelagic), but they also spend a lot of time in coastal waters. They spend most of their lives in waters between 70° and 83°F.
While Sailfish have been caught in the Mediterranean Sea, they’re not common there. Rather, they occupy the Atlantic ocean between the Tropic of Cancer and the Tropic of Capricorn, give or take a few longitudinal degrees.
As carnivores, Sailfish eat other fish. They are predators and are relatively high on the hierarchy of those in the ocean, as there aren’t many other creatures who go after them.
Sailfish use their dorsal fin— their sail— in hunting. They eat squid and octopus, but they do a good deal of their hunting near schools of fish.
Smaller fish like anchovies and sardine make up the bulk of the Sailfish’s diet. They use their dorsal fin to shepherd the fish where they want to go, ushering them to the Sailfish’s dinner table.
But they don’t eat the fish yet. They use their upper jaw (the “sword”) to slash at the fish— individuals or groups— to stun them and otherwise beat up on them.
Swinging that sword, a Sailfish can turn its tip through as many as 575 degrees in one second.
With the sword moving so quickly, the smaller prey fish do not have fast enough reflexes to dodge it, and they get beaten and battered.
Once they’re bruised and exhausted, they can’t escape the Sailfish when it begins feasting on the defeated fish.
Sailfish also eat mackerel, needlefish, and herring and most often feed during daylight hours, though night hunts are not uncommon.
As one of the ocean’s top predators, Sailfish face few threats under the ocean waves, though juveniles can fall prey to larger creatures. Human activity is a much more significant threat.
While global warming and climate change— human-driven forces— affect the Sailfish as much as any other living creature on earth, the only direct threat to Sailfish from humans is via sports fishers.
Game fishing for Sailfish is a popular and big business since the trophy fish has a distinctive look.
Sailfish meat is considered tough and relatively unpalatable, so commercial fisheries do not threaten them.
As the planet warms— and the oceans with it— ocean acidification grows into a bigger problem every day. But the threat to Sailfish comes from the falling oxygen levels in the sea.
Deeper waters contain less and less oxygen as global warming continues, so Sailfish and other billfish are diving deep with decreasing frequency.
While larger fish may occasionally feed on Sailfish, their main oceanic threat is the dolphinfish, also known as the mahi-mahi.
They may also get fed on by larger seabirds, and since the Sailfish are spending more time near the surface due to low oxygen levels, these birds have more opportunities to feed on them.
Another significant threat to Sailfish is commercial fishery activity. While the fisheries do not target Sailfish, they can get caught in trolling nets.
This happens mainly with commercial tuna fishing, though any net-based commercial fishing presents a risk to Sailfish or any other fish unfortunate enough to be in the wrong place at the wrong time.
While the Sailfish is not endangered or even threatened, commercial vessels in the United States may not buy or sell any billfish.
Sports fishers need a NOAA permit to fish for Sailfish in federal waters, and many coastal states have laws governing fishing for Sailfish and others like it.
- Sailfish can swim up to 70mph.
- Scientists disagree as to whether there are one or two species of Sailfish.
- Sailfish change colors depending on their mood and level of excitement.
- They have a mechanism in their brains that serves as a brain heater for when Sailfish dive into deeper, colder waters.
- Sailfish also have specialized photoreceptors in their eyes to make it easier for them to see in deep water, which doesn’t get much light.
- They can live as long as 15 years, though the average lifespan is much lower.
- A Sailfish egg hatches within three days of fertilization.