How long do marlins get

Like many migratory species, the females are larger than males. In fact, adult female blue marlin are as much as four times the size of the largest males. All of the largest individuals are female.

Once the sperm find the eggs, fertilization occurs. While spawning, a single female may release several million eggs, increasing the likelihood that some will be fertilized and that at least one hatched larva will grow to reach adulthood. Though almost all fishes are cold blooded, blue marlin and the other billfishes have a specialized blood vessel structure — called a countercurrent exchanger — that allows them to warm their brains and eyes.

This adaptation provides them with a major advantage when hunting, by allowing them to think more quickly and see more clearly. The blue marlin is a targeted fishery species in only a limited number of areas but is captured as accidental bycatch in fisheries targeting other species throughout its range. In some areas, this accidental capture is threatening blue marlin populations, and scientists consider the species vulnerable to extinction. Generally speaking, blue marlin populations are decreasing in numbers.

Though it is not targeted commercially throughout much of its range, the blue marlin is one of the most highly sought after big game fishes in the world.

Sport fishing enthusiasts spend tens of thousands of dollars to catch large blue marlin, and they are typically released alive though recent data suggests that released individuals may frequently die after the fact. If numbers continue to decline, this highly valuable sport fishery may be in danger of collapse.

Taxonomy note: Several times throughout the history of studying marine fishes, researchers have divided the blue marlin into multiple species, but recent genetic studies leads scientists to believe that all blue marlin around the world are the same species.

Click here or below to download hands-on marine science activities for kids. NOAA Fisheries. Ocean Fishes Blue Marlin Makaira nigricans. Bycatch Regulations are in place to minimize bycatch in the tuna and swordfish fisheries, which incidentally catch the most commercially available blue marlin. Blue marlin are deep cobalt blue on top and silvery white on the bottom.

They have a pronounced dorsal fin and a long, spear-shaped upper jaw bill. Blue marlin may grow to be more than 12 feet long and may weigh up to 2, pounds. Female blue marlin grow larger than males and may live 20 years. Male blue marlin reach 7 feet in length and may live up to 10 years. They grow fast and may reach 3 to 6 feet in the first 1 to 2 years of life.

Males mature around 2 years old, and females mature between 3 to 4 years old. Blue marlin spawn between May and September. They eat mostly tuna and other open water fishes. Blue marlin live throughout tropical and subtropical waters of the Indian, Pacific, and Atlantic Oceans. Permits and logbooks are required. Observers are required on all Hawaii-based longline vessels.

NOAA Fisheries vessel monitoring system program requires longline boats to be equipped with a satellite transponder that provides real-time vessel position updates and tracks vessel movements. Longlines are prohibited in certain areas to protect endangered Hawaiian monk seals and reduce the potential for gear conflicts and localized stock depletion.

Vessels operating under longline general permits must carry special gear to release incidentally hooked or entangled sea turtles. Fishing gear requirements apply to all Hawaii longline limited access permitted vessels. The requirements may change depending on type of fishing trip, location of fishing, and how the gear is set.

An overview of gear requirements can be found here. Management of highly migratory species, like Pacific blue marlin, is complicated because the species migrate thousands of miles across international boundaries and are fished by many nations.

Effective conservation and management of this resource requires international cooperation as well as strong domestic management. These Commissions rely on the scientific advice of their staff and the analyses of the International Scientific Committee for Tuna and Tuna-like Species in the North Pacific ISC to develop and adopt international resolutions for conservation and management measures.

Working with the U. Commercial fishery: Marlin are primarily caught incidentally in pelagic longline commercial fisheries for tuna and swordfish.

They are also a popular target fish for recreational fishermen. In , commercial landings of Pacific blue marlin from the waters around Hawaii totaled more than 3. The Billfish Conservation Act , along with existing billfish regulations, prohibits the sale and commercial possession of billfish and billfish products.

Gear types, habitat impacts, and bycatch: U. Fishing gear used to catch tuna and swordfish rarely contacts the seafloor so habitat impacts are minimal. Restrictions on the type of fishing gear that can be used, and prohibitions on fishing in certain areas, minimize impacts on protected species.

Interactions with protected species such as sea turtles, marine mammals, and seabirds in these fisheries are rare and survival rates are estimated to be high for all gear types. Longline fishermen are trained in safe handling and release techniques for sea turtles, seabirds, and marine mammals, and they carry and use specific equipment for handling and releasing these animals.