Article by Capt. Mark Sampson
I recently reviewed a publication I had on file from the National Marine Fisheries Service (NMFC) about the Atlantic highly migratory species they manage.
The report was from a few years old and essentially a rundown of the status of the HMS fishery, new rules and regulations that were up for consideration, and how those rules might impact fishermen.
Even though the report was a bit dated, I did find some interesting facts in it's description of the different fish covered by their HMS management plans. I’ve always maintained being well educated about the different fish we pursue not only makes us better fishermen, but also gives one a better appreciation, and concern, for the well-being of all of our marine resources. Seeing this kind of stuff coming from fishery reports and publications also makes me feel a bit more confident that those involved with managing our resources know a lot more about the different species that we fishermen often give them credit for. So here’s a few “fun facts” from the report:
Atlantic Swordfish
Reaching a maximum size of about 1165 pounds, Atlantic swordfish are one of the largest and fastest predators in the Atlantic Ocean.
Like sharks, swordfish must continually swim with their mouth open to keep water flowing across their gills to maintain an oxygen supply. This process is known as “ram gill ventilation” and is believed to conserve energy better than the more common mechanism used by most fish where water is pumped across the gills.
Because they do not have the ability to contract, swordfish’s eyes produce heat when stimulated by the nervous system, which in turn warms the eye and brain tissues. This allows the fish to more effectively hunt in deep, cold-water environments without experiencing a decrease in brain and visual functions.
Atlantic Bluefin Tuna
Bluefin tuna are known as fish that are of a late age when they become sexually mature and can live to a relatively old age. The oldest age recorded from a tagged bluefin was one that was about two years old when tagged and was recaptured 18 years later.
Bluefin tuna from the western Atlantic generally reach a larger size than those of the eastern Atlantic.
Western Atlantic bluefin first spawn at about eight years old from mid-April into June in the Gulf of Mexico and the Florida Straits.
Atlantic Bigeye Tuna
Exhibiting very extensive vertical movements, bigeyes are actually able to dive deeper than other tuna species. They become sexually mature at about age three and a half and spawning takes place in tropical waters.
Atlantic Yellowfin Tuna
Small yellowfins will congregate near the surface in mixed schools with skipjacks and juvenile bigeyes.
Yellowfin growth rates depend on the size of the fish. Young fish grow slowly at first but faster after they leave the nursery grounds and most of the large yellowfins caught by fishermen are males.
Blue Marlin
Young blue marlin are one of the fastest growing of the bony fishes. They can reach close to 100 pounds after their first year. Females grow faster and reach a larger maximum size than males. The life expectancy for blue marlin is 20-30 years.
Blue marlin have relatively small stomachs which reduces the proportion of the body needed for “guts” and allows more volume for muscles. This translates into more swimming speed and endurance.
White Marlin
White marlin have a life span of about 18 years, they grow quickly and mature females are larger than males.
In July of 1995 a white marlin was tagged off Cape May NJ. It was recaptured off West Africa in November of 1996. The track covered 3,517 nautical miles in 476 days and is the longest recorded distance for one of these fish.
Some of the largest prey found in white marlin stomachs includes snake mackerel over 28-inches long.
Sailfish
Sailfish are probably the slowest growing of the Atlantic billfishes. The longest a tagged sailfish has gone from capture to recapture is 16.1 years and most sailfish caught off Florida are under three years of age.
Adult sailfish have few natural enemies but studies show that they are sometimes preyed upon by killer whales, bottlenose dolphin, and sharks.
Sharks
There is a lot still unknown about the natural life span of sharks, but for many species it is believed to be 30-40 years or longer.
Compared to other fish, sharks have a low reproductive potential. Species such as the sandbar, lemon, and bull shark do not reach sexual maturity until 12-30 years of age.
There are 73 species of sharks known to live in the Atlantic coastal waters and since 1962, volunteer recreational and commercial fishermen, scientists, and fisheries observers have tagged over 128,000 sharks representing 40 different species. §
