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Maryland's Big Game Billfish - August 7, 2016

                Billfish are touted as some of the most prized big game fish in North America, as demonstrated by tournaments such as the White Marlin Open and the Mid-Atlantic $500,000. Billfish are distinguished by a long, spear-like rostrum that is used to stun and kill prey, and by prominent dorsal fins that run along a large portion of their body that help with swimming stability and control. The billfish family includes species such as sailfish, spearfish, swordfish, and marlin. These apex predators are highly migratory and can be found throughout the world’s oceans, primarily in tropical and sub-tropical waters. The species found off Maryland’s coast include swordfish, sailfish, roundscale spearfish, blue marlin, and the famed white marlin.

                Most billfish, including sailfish, spearfish, and marlin, belong to the taxonomical family Istiophoridae. Sailfish are some of the fastest fish in the ocean; reaching speeds of more than 68 miles per hour, which is about the same speed as a cheetah. Sailfish are distinguished by their large and colorful dorsal fin, which give them their common name. A unique characteristic of sailfish is that they have the ability to change their coloration based on their level of excitement. It can change from dark blue and white to light blue with yellowish stripes to confuse prey so they are easier to capture and eat.

                Swordfish have the widest habitat range of billfish, due to their ability to tolerate a wide range of temperatures in their search for food. Warm water habitats are preferred, but swordfish have been found in waters near freezing temperatures. Unlike other billfish, swordfish are the sole member of the taxonomical family Xiphiidae. The bill of a Swordfish is much longer proportionally to its body than that of other billfish species, hence their common name.

                Blue marlin are one of the largest billfish species, and are easily recognized by their cobalt blue and silvery coloration. They can reach lengths of over sixteen feet and weigh over 2,000 pounds, with females being significantly larger than males. Marlins will use their bills to slash through schools of fish and return to eat their wounded prey.

                The roundscale spearfish is recently discovered species of billfish. Prior to their discovery, this species was often mistaken for either white or hatchet marlin due to their similar appearances. The primary differences in appearance are truncated anal fins and distinct round scales on the spearfish. While marlins have rounded anal fins but occasionally they can appear to be truncated, like the spearfish. Roundscale spearfish made up 27% of the commercial catch that was previously thought to be white marlin. Genetic testing on white marlins caught in recreational tournaments show that about 18% of white marlins weighed in are actually roundscale spearfish.

                White marlin are only found in the tropical and warm temperate waters of the Atlantic Ocean. They are among the smaller species of billfish, with lengths up to nine feet and weighing up to 200 pounds. Similar to sailfish, white marlin can change their coloration based on their level of excitement. Due to the recent discovery of the roundscale spearfish, population estimates for white marlin may be overestimated as the two populations were counted as one.

                Marlin populations are in decline due to increased pressure from the commercial fishing industry. In the United States, only the recreational fishery is allowed to fish for billfish. Commercial fishing vessels are required to release all billfish however, 25-30% of all marlin caught on commercial longlines are dead prior to arrival of commercial vessels. Commercial fishing methods such as longlines, gillnets, and purse seines are responsible for about 99% of reported Atlantic marlin kills. Recreational fishing is only responsible for less than 1% of marlin kills due to their catch and release methods to help conserve the population. Circle hooks are being used by the recreational fishery as they have been shown to reduce release mortality and are more likely to hook in the jaw reducing injury.

                The Billfish Conservation Act of 2012 was a large step in billfish protection. The act bans the sale of all species of billfish, excluding swordfish, in the United States. Traditional fisheries in Hawaii and the Pacific Islands are still allowed to sell billfish, however. The importation of foreign-caught billfish is also banned under the act; which is an estimated 30,000 billfish a year.

                Billfish are apex predators in the food chain and help maintain healthy marine ecosystems. They are renowned as prized game fish and bring in millions to the local economy by way of billfish tournaments. The importance of promoting sustainable fishing methods, good stewardship, and proper handling of all hooked fish cannot be overstated, and will lead to the continued survival of these grand fish of the sea.

 

Phillips is the Program Manager for the Maryland Coastal Bays Program.



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