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Shortnose Sturgeon fish identification, its habitats, characteristics, fishing methods.
The shortnose sturgeon, a swimming fossil among the oldest living species, is a primitive fish predating dinosaurs, back 65 million years, characterized by rows of armor-like plates along its sides and a mostly cartilaginous body. Its name refers to its short shovel-shaped snout. Rarely exceeding 3-4 feet in length, the shortnose is a very small sturgeon. Its body is usually olive-yellow to bluish gray with a white to yellow belly. Only occasionally entering the open sea, the shortnose lives in rivers, lakes, estuaries, and bays along the Atlantic coast from New Brunswick, Canada to Florida.
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The shortnose sturgeon (Acipenser brevirostrum) is one of smallest sturgeons, growing to 2 to 4 feet in length and about 14 pounds in weight. Shortnose sturgeons are found along the Atlantic coast of North America in estuaries and large rivers: St. John River in Canada to St. Johns River in Florida. There is a partially landlocked population in the Connecticut River.
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Description
The Shortnose sturgeon has a short and rounded conical snout, bluntly V-shaped, not upturned at tip, four short barbels in front of its large underslung wide toothless mouth, numerous dorsal, lateral and ventral scutes (unique body armor of diamond-shaped bony plates), and a heterocercal tail (the upper lobe of the tail fin is larger and contains the upturned end of the spinal column). The Shortnose Sturgeon has small eyes because they rely on whisker like feelers called barbels to find food, touch and taste things. The mouth is sucker shaped and under the head because they feed off the bottom. Five rows of bony plates (called scutes) occur along its body: 1 on the back, 2 on the belly, and 1 on each side. Absence of fontanelle and post dorsal shields is distinguished characteristics.
Distinguish Characteristics
- Dorsal soft rays: 33–42
- Anal soft rays: 18–24
- Single row of pre anal shields, 6-11
- Dorsal shields 7-13
- Lateral shields 22-34
- Max length: 49 in (143 cm)
- Max weight: 7 lb 4 oz (23.0 kg)
- Max age: 67 years for female and 32 for male
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The body is generally olive-yellow or yellowish brown and to gray or bluish on the back above the upper lateral line of shields, nearly black on the head and side’s level to lateral plates, marked with alternate black and pale bands, and milky-white to dark yellow on the belly. The peritoneum (body cavity lining) is black.
Length at initial maturity for this species occurs between 45-55 cm fork lengths, from the snout to the middle of the tail (18-22 in.). Males may mature when only 19-20 inches long and most of them do by the time they pass 21 inches; most of the females at about 24 inches. Maximum known fork lengths are nearly 49 in. for a female and nearly 39 in. for a male.
The Shortnose sturgeon resembles the Sea sturgeon especially when young with some noted most obvious differences. This is a much smaller fish than the sea sturgeon. The shields in its dorsal row are relatively smaller, and each shield is separated from the next by a space up to 1/2 as long as the shields themselves while dorsal shields are contacted or overlapping in the sea sturgeon. The space between its dorsal row of shields and the upper lateral row on each side is only sparsely set with fine prickles while it is closely set with coarse prickles in the sea sturgeon. Its viscera are blackish and pale in the sea sturgeon. Shortnose sturgeon has 18-24 anal soft rays’ averages and sea sturgeon has 23-30 rays. The snout and broader in young shortnose are shorter than in sea sturgeons of equal size. When fully grown, sea sturgeons have their snout much larger that the Shortnose.
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Habitats
Shortnose sturgeons rarely venture into the river’s larger tributaries, and they are usually found in the main stems, river mouths, tidal rivers, lakes, estuaries, and bays. Those are the prime habitat for the shortnose sturgeon. However some individuals occasionally enter the open ocean. Shortnose sturgeon do not appear to make long distance offshore migrations.
Bottom feeders, shortnose sturgeon eat a variety of organisms. Using their barbels to locate food and their extendable mouths to then vacuum it up, they eat sludge worms, aquatic insect larvae, plants, mussels, snails, shrimp, and crayfish. Juveniles eat mainly midge larvae and amphipods, along with other available benthic crustaceans and insects. Adults in freshwater will consume mollusks, crustaceans, and insect larvae. In estuaries, adults will eat polychaete worms, crustaceans, and mollusks.
Spawning
Shortnose sturgeons are typically anadromous, migrating from the ocean salt water to fresh water specifically to reproduce, except some populations that are partially landlocked, moving between fresh and salt water. Males reach maturity in approximately 3 years (females 1–2 years later up to 5 years) in southern rivers to 12 years for both sexes in northern rivers, at 18 to 22 inches (45 to 55 cm) in length.
Spawning always occurs in fresh water, above the head of the tide, in moving water over rubble or gravel bottoms with little silt or organic material. They spawn within a 1- to 3-week period in late winter and early spring, from January to May, with water temperatures from 44 °F to 59 °F (6.5 °C to 15 °C) while 48 °F to 54 °F (9 °C to 12 °C) is optimal. If temperature or any other environmental conditions are not acceptable, shortnose sturgeon will not spawn, resorbing their eggs and milt (sperm). Most shortnose sturgeon females spawn every 3 to 5 years while males spawn every other year. Females lay between 40,000-200,000 eggs, depending on size in areas with rocky bottoms or gravel. They don’t guard their eggs.
The eggs hatch after 13 days, into 7–11 mm long fry with a large yolk-sac, very poor swimmers that drift downstream with the currents under any available object on the bottom and remain there for 9–12 days where they continue to live off nutrients provided by their yolk. After that they mature to a swimming larval stage at about 1 inch (12-15 mm) in length, start looking like tiny adults when they reach 20mm in length and begin feeding. As they grow and mature, the fish move downstream into the most brackish water, in the deep channels of the river, in area with low enough flow that they can feed in less turbulent water, and remaining in fresh water for the first year of their life. Juveniles, up to 18 inches long, spend their tidal cycle in the area where fresh and salt water mixed together.
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Fishing Methods
White sturgeon is an excellent food fish that is sold fresh, smoked or frozen. Worldwide, sturgeon commercial fisheries use sturgeon for meat and eggs, the eggs being most sought after. Caviar is considered a delicacy in many parts of Europe and North America. White sturgeon have been a very important fish, both commercially and for sporting purposes, recently became a popular target fishery in the Columbia River production, with its valuable roe for caviar, is the second only to the Soviet Union's production. The white sturgeon is also an important fish for Native American fishermen on the Columbia and Klamath rivers.
Some sturgeons are caught with hook and line gear or hoopnets from platforms along the shore. In the Columbia River, size restrictions make it very unlikely any fishers ever legally retain egg bearing fish. The fish caught legally by sport and commercial fishers are too small and not yet sexually mature enough to make harvesting for eggs worthwhile.
Bait used for sturgeon is mostly its natural prey including shad, anchovies, shrimp, and smelt. Sometimes cheese, anchovies, pickled squid, dog food, and cat food could be used as bait. A strong, 10–12 foot (3.1–3.7 m) long rod and heavy salt water reel spooled with 40–100 pound test fishing line is used for bank fishing. For boat fishing a smaller 6–7 foot (2 m) long rod is used. Anglers vary the amount of weight used depending on how heavy the current is, anywhere from 6 to 20 ounces (210–560 g). Often, an angler will use a 10–12 inch soft braided leader to connect the weight to the hook. When sturgeon first encounters the bait, they mouth it to taste and feel it before inhaling it whole.
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