Latin name

Ammodytes americanus

Other name

American sand eel

Identification

Like all lances, the American sand lance has a long, slender body with a pointed snout. The mouth is large and toothless, with the lower jaw protruding well beyond the upper. 

When watching a fish swim, it can be observed to make sinusoidal swimming motions similar to those of an eel. The undulating movements begin at the head and extend down the body. This curved body shape aids in eluding prey due to its high agility and ability to glide along the bottom.

Features of fish fins

The American sand lance has a long, low dorsal fin (described as "very thin") that extends along most of its back and folds into a depression at the base of the fin when not in use. Its anal fin is about the same height as the dorsal fin and runs along the back third of the fish's body. Its pectoral fins are small and its caudal fin is bifurcated.

Fish colouring

The body coloration of the American sand lance is generally greenish-silver, with a muted brownish-green dorsal that transitions to white flanks and belly, a camouflage known as countershading. A visible lateral line separates this color transition, running down the body and ending at the caudal peduncle. The elytra are silvery white, matching the color of the abdomen. The eyes are silvery with a dark pupil. The fins are pale brown and are difficult to see when examining the fish.

Distribution

American sand lance have been found from Cape Hatteras, North Carolina to Labrador in the Northwest Atlantic.

Habitat

Historically, this fish has inhabited bays, estuaries, and coastal shallows at depths of less than two meters. In order for this species to have a suitable habitat, there must be substrate available for them to burrow into. Substrates that attract fish include clean grains of sand or gravel and crushed shells. This choice may be because larger grains are easier to move and because the substrate may hold more dissolved oxygen.

Size

Adult fish are usually 4 to 6 inches (10 to 15 cm) long, although some fish can reach 7 inches (18 cm). A. americanus, like other Ammodytes species, mature within the first year after hatching. Males of A. americanus reach a smaller size than females, about 85 mm, as opposed to females which reach about 90 cm. There is no noticeable difference between the final length of males and females, although males reach a smaller size than females. Fish caught in more northerly waters tend to be longer than those that swim in the southern waters of Northwest Asia. 

Behavior

The schools that these fish form number from a hundred to many thousands of individuals, which is relatively small for fish schools. The schools are visually arranged vertically and densely packed, with the average distance between two individuals being ½-¾ of their body length. The size of an individual school, when measured, was 1-5 meters wide, 0.5-1.5 meters high, and 3-20 meters long. The schools swim at a speed of about 30-50 cm/s. This type of school is a stratified school. When attacked, the school will split or scatter to avoid encountering what they believe to be a predator. Disturbed fish break up into small groups and sink to the bottom. They begin digging into the sand at 60°-75° until they move to an angle of 20°-40° when a quarter of their body is covered. They continue burrowing at a new angle until they are completely buried. Once inside a burrow, the fish only open their heads to survey their surroundings. Some will even move to another location and surface if further disturbed.

Food and feeding habits

American sand lance have been found to feed primarily on copepods, small crustaceans, making them a zooplanktonic fish. These crustaceans are the main source of nutrients for the lance and were found in 37.8% of the stomachs examined in one study. The abundance of other prey varies seasonally. Stomach contents during the fall months show that the diet consisted mainly of paddlefish and mysids. During the spring months, paddlefish, hydroids and cumaceans were found, indicating a benthic diet. Paddlefish continued to be favored during the summer months. Bottom crustaceans, small snails and crabs, and isopods were also found. The American sand lance was found to feed both day and night, which is not the case with other Ammodytes. In European waters it feeds only during the day.

Reproduction

Females lose up to 45% of their body weight during spawning. The egg is opaque in appearance, with an average size of 0.05-1 mm. Yellow globules of yolk and oil are visible inside the egg. The spawning season lasts from December to March and is completed by June, once a year after the female reaches sexual maturity. In December, the sex glands of the females tend to be more developed than those of the males. After hatching, the fish develop with pigmented eyes, a functional mouth, and a complete intestine. After hatching, it can take more than a hundred days for the first calf to undergo metamorphosis. Gathering behavior is observed on day 90 and schooling behavior on day 133. Burrowing in the sand, the fish can remain hidden for several days, then emerge in small groups of two or three individuals and begin to forage. American sand lance are highly fecund, which is a major reason why they have adapted so well to cold winter waters with low zooplankton.

Fishing

American sand lance are not fished, but are affected by fishing and caught as bycatch in some northeastern fisheries.

Relationship with a person

Harmless.