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BASS VS BLUEFIN

A look at two of the northeast’s most popular saltwater gamefish: the striped bass and the bluefin tuna.
By Capt. Al Anderson
Tags: offshore, special

There is no doubt that the striped bass and the bluefin tuna are the most popular gamefish in northeast waters. Knowing their biological differences will help shed light on why different techniques work to catch them. Here’s a brief comparison sure to spark arguments over which is a greater gamefish.

SPEED & MUSCLE
Short burst swimming speed of several bluefin tuna in captivity were measured at 18 body lengths per second, which computes to 45 mph; about 3X faster than a stripers. They have a sustained swimming speed of up to 8 mph, 24 hours a day, which could result in their covering nearly 200 miles. A tagged bluefin we recaptured off Block Island had been tagged off New Orleans, LA 10 days prior, nearly 1600 miles away.

Like most tunas, bluefin have high amounts of red muscle for sustained swimming, whereas their white muscle is used for fast, short burst swimming. Red muscle contains high amounts of myoglobin, a protein that stores oxygen within the tissues, which is prized as table fare. White muscle contraction is anaerobic; the energy comes from glycogen stored in the tissues.

White muscle, like that in a striper filet, comes into play when chasing bait in a river mouth rip and does not require the huge amounts of oxygen necessary for foraging open-ocean waters. However, when very strong currents mandate active swimming by stripers, research tells us they simply slide away and wait for it to subside.

ON THE MOVE
Years ago a school striper I tagged while fishing Nova Scotia’s Annapolis Basin was recaptured the following spring in the Choptank River in Maryland, over 900 miles away. Stripers we tagged at Block Island were recaptured from Cape May, NJ less than two weeks later, nearly 200 miles distant. Other stripers we’ve tagged at Block Island have been recaptured at Nauset Beach on Cape Cod seven days later. Who knows how long any of these fish were there before being recaptured?

For years I’ve sent school bluefin tuna tissue samples (finlets) to scientists at the Virginia Institute of Marine Science studying genetic (DNA) profiles. Would it surprise you to learn that we here in southern New England have been catching Mediterranean-spawned school bluefin for years when we thought they were Gulf of Mexico origin fish?

GAS EXCHANGE
All tunas are what we call ram gill ventilators, which means they open their mouth while swimming forcing water over their gills. Striped bass are capable of doing this as well, but only for a very brief period. This method of gas exchange is highly efficient. Tuna have a huge gill surface that works to control body temperature, but more importantly to fuel the muscles that propel them. Gill surface area in a bluefin is about 10X that of a similar-sized striper.

Removal of one waste product—carbon dioxide—from muscle contraction is of paramount importance. Should it fail, lactic acidosis results, producing fatigue. You want to bring a tuna to the boat quickly? Simply slowing its swimming speed down reduces the flow of water over the gills which, in turn, forces the fish to slow down. Light drags and long fight times elevate body temperatures and produces high levels of metabolic waste. Should they reach critical levels, the fish cooks itself and succumbs making the flesh unpalatable.

Years ago I examined the scales from an 85-pound striped bass taken in a net from Chesapeake Bay which showed 24 distinct and four indistinct rings, indicating the fish was around 28 years old.

TAILS & SCALES
All scombrids (mackerel family) have narrow, rigid, lunate-shaped tails. Fish with “high speed propellers” have a body that stays stiff while muscles transmit their contractions via tendons to the tail. Just like those high-speed racing boats that have narrow-bladed props that spin at very high rpms. Stripers, on the other hand, have a slow tail beat that produces thrust through a wide, soft, forked tail, much like that of the slow turning but massive blades of a tug boat propeller. This provides them with superior agility when chasing prey in turbulent surf zones.

The few scales tuna have are small and thin, covered by a layer of mucous that helps reduce drag. Unlike the scales of a striper that are large and thick, working to protect them from injury when in a rocky surf zone. For a tuna, speed is more important than protection from mechanical injury, and hence some species, including the bluefin, have evolved an unscaled aft portion of its mid-section to reduce drag.

Each scale shows annuli (growth rings) when examined under a microscope, much like the rings seen on the end of a cut tree trunk. Years ago I examined the scales from an 85-pound striped bass taken in a net from Chesapeake Bay which showed 24 distinct and four indistinct rings, indicating the fish was around 28 years old. Whether tuna or striper, once scales are lost, they are soon replaced but appear granular with no growth rings.


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