Family: Istiophoridae (Billfishes)
Genus and Species: Tetrapturus audax
Range: Striped marlin occur in tropical and warm temperature waters of the Indian and Pacific Oceans. On the west coast of the United States they range as far north as Oregon, but are most common south of Point Conception, California. They usually appear off California in July and remain until late October. They appear to be predominant species of Kenya, Mozambique, Mexico, Ecuador and New Zealand. Commercial fisheries catch them all the way across the Pacific. Striped marlin have traveled up to 31 miles per day. The longest southern migration was 1,153 miles from the tip of Baja near Clipperton Islands in seventy-one days. The longest migration of any billfish was by a striped marlin, tagged and released near the tip of Baja, and then recovered 200 miles southwest of the Hawaiian Islands three months later, a distance of about 3,120 miles. Most of the striped marlin wander in the ocean alone, but, as with all marlin when breeding, they may be in pairs or schools.
(click image to view anatomy)
Description: The body of the striped marlin is elongate and compressed. The upper jaw is much extended, forming a rounded spear. Smaller than the blue marlin, the striped marlin has a dark steely blue back that is lined with dark cobalt blue or lavender stripes (coloration varies with
location), fading to a silvery white underside.
Of the billfishes that occur in California waters, the striped marlin is difficult to confuse with the others. Marlin have scales, fins on the belly, and a rounded spear which set them apart from swordfish which have no scales or ventral fins and have bills that are flat. Sailfish have an extremely high dorsal fin not found among the marlins, and shortbill spearfish do not have the long spear on the upper jaw nor the body weight of the marlin. The striped marlin normally develops conspicuous stripes along the sides of its body after death. This feature is unique to striped marlin.
The first dorsal fin at its highest point, is from 75% to a 100% of the body depth, measured at that point on the body, with the length going back to almost the second dorsal fin. The striped marlin's dorsal fin is generally higher in its total height than other marlin species. The dorsal fin has many dark black to purplish-black spots scattered throughout with a light purplish or violet blue background. The anterior part of the dorsal is pointed like the blue marlin. The second dorsal is slightly posterior to the second anal fin and is also pointed.
The pectoral fins of the striped are pointed, fold easily against the body and are slightly shorter than the longer pectoral fins of the sailfish. Striped marlin pectoral fins are generally straight, with a slight curve on the bottom. However, they are not as curved as the blue or black marlin, nor are they as wide as the blue or black marlins.
The striped marlin has the most pronounced vertical line markings, hence the name. Generally fourteen to twenty vertical stripes from the true gill plate to the caudal peduncle. The stripes are prominent lavender to blue in color and they appear wider than the stripes on sailfish and seem to be made up of various size dots to form lines. The striped can "light up" to a very brilliant lavender to purple. The other marlin have the ability to "light up" but not to the same intensity as the striped marlin. The body scales are covered with a layer of heavy skin so they are not easily seen. The scales are single or unbranched, similar to the black marlins only smaller.
Natural History: The food of striped marlin is predominately fishes, squid, crabs and shrimp. The latter three make up lesser portions of the diet than do fish.
The spear of the marlin is sometimes used as a weapon for defense and as an aid in capturing food. Wooden boats frequently have been rammed by billfish, and in one instance the spear penetrated 18.5 inches of hardwood - 14.5 inches of which was oak. When it uses its bill in capturing food, the striped marlin sometimes stuns its prey by slashing sideways with the spear rather than impaling its victim, as some believe.
Since marlin cannot yet be accurately aged, the age and duration of different life stages cannot be determined. Females are reported to reach first maturity at 50-80 lb.; it is not possible to determine onset of sexual maturity in males because change in the size of testes is slight. Striped marlin are believed to spawn in the northwest Pacific and migrate eastward as juveniles, which would account for the abundance of smaller fish in Hawaiian waters.
Fishing Information: Most striped marlin are taken by trolling artificial lures in areas they are known to inhabit. Blind strikes are generally the rule, but one can occasionally tempt a "finner" or "sleeper" (marlin swimming along the surface) to strike if lures are trolled past the fish. Live bait such as tuna, dorado or mackerel also work well but requires more effort since the fish must usually be first spotted visually. Once a striped marlin is located, the angler should cast a bait in front of and past the fish so it can be reeled back towards the animal. Strikes usually result from properly presented live bait. Most striped marlin anglers prefer Pacific mackerel as bait. The best California fishing locality is in a belt of water which extends from the east end of Santa Catalina Island offshore to San Clemente Island and southward in the direction of the Los Coronados Islands. Other hot spots include New Zealand and Baja California.
Temperature Range: 70 - 86° F.
Conservation: Like all billfish species, the striped marlin population has been significantly reduced as a result of intense commercial and recreational fishing pressure. As populations of billfish decline, many organizations are working to protect these amazing blue water hunters. Several conservation groups are proposing area closures and establishing conservation zones for billfish protection. While catch and release practices are more prevalent these days, many fish are still being killed.
Other Common Names: striper, marlin, nairagi, Pacific marlin, spikefish, spearfish.
Largest recorded: 13.5 feet, 339 pounds (California); 494 pounds (New Zealand)
Sources: Marine Sportfish Identification, California Department of Fish and Game, 1987; FishBase, FishBase Consortium, 2001; Billfish, Saltaire Publishing, 1976
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