In the lower Connecticut River, fisheries' biologists are studying shortnose sturgeon; primitive, bizarre-looking creatures that are considered some of the rarest fish in the United States.

Sturgeon are essentially living fossils and exhibit several primitive features: a mostly cartilaginous body, a shark-like tail, rows of sharp, bony plates and prominent barbels, which are used for finding freshwater mussels, worms and other small creatures. Because they’re bottom feeders and don’t strike at bait, short-nose sturgeons are rarely caught or seen, even though they’re one of the biggest fish in the river. A large short-nosed sturgeon can be nearly 3 feet long and weigh 25 pounds.

Historically shortnose sturgeon were plentiful and lived in all the major coastal rivers from New Brunswick to Florida but today, they’re found in only 16 rivers. Their decline began 300 years ago with the arrival of Europeans. From the colonial period until the mid-19th century, shortnose sturgeon and their much larger cousin, the Atlantic sturgeon, were caught by the tens of thousands for meat and eggs, which brought high prices as caviar. In addition to overfishing; dredging, pollution and dams nearly drove the species to extinction. Dams, in particular, were a big problem because they blocked the fish from traveling upstream to their specialized spawning grounds.

In 1973 the US Congress passed the Endangered Species Act and shortnose sturgeon received federal protection. Although biologists knew that shortnose sturgeon were rare, little was known about their biology. Where did they spawn, how long did they live, how often did they breed, what was their seasonal pattern of movement? Basic questions, but hard to answer since you can’t see them down at the bottom of the river. One of the most effective techniques for getting some answers to these questions is through radio telemetry. By attaching a radio transmitter to some these fish we can track their movements. But to do this, first you’ve got to catch’em.

Over a month, a series of bottom nets in sections of the river where we know there’s a population of shortnose sturgeon were set up. As they migrate upriver, the adults get hung up in the nets. The researchers make a point of getting out every morning, no matter what the weather’s like, to check on what has caught.

If the crew finds a sturgeon in their net, they take several measurements, attach an identification tag to the fin and then release the fish. On a few sturgeon, they insert a small radio transmitter just behind the dorsal fin. Each radio emits a unique frequency that enables the researchers to track the movements of individual fish for 1-2 years until the battery dies. On a calm day, the signal can be detected from as far as a mile away.

To find the fish, a large antenna is used. With radio telemetry, it has been learned that after spawning in the spring, shortnose sturgeon travel downriver to less than half a dozen, special feeding areas. These summer feeding grounds are probably selected because of the abundance of freshwater mussels and snails. They stay in these areas until early fall when the water temperatures drop to about 8C. Then, the sturgeon move to overwintering areas, usually deep holes, 20-40 feet deep, where the fish remain essentially inactive until the water temperature rises in the spring.

Next spring, when the water temperatures reach about 6 C, a small percentage of adults will migrate upriver to spawn. But not just anywhere. The habitat they select is very specific and is characterized by swift water with a silt free cobble or boulder bottom. If the water temperature and speed are just right, the sturgeon will spawn. Each female releases between 100-200,000 eggs, each of which is coated with a sticky outer layer that glues it to the cobbly bottom.

In about a week, the young sturgeon hatch and immediately wiggle down and hide in the dark rock crevices but in only a few weeks they can swim and actively hunt. During its first year of life, a short nose sturgeon can grow up to a foot. But this rapid rate of growth slows down, and in fact, it takes between 5 to 8 years for a sturgeon in our area to reach sexual maturity. On top of this relatively long maturation time is the fact that female sturgeon breed only every 3 to 5 years.

Along with this slow rate of reproduction, the lack of suitable spawning habitat and presence of dams continue to inhibit the recovery of shortnose sturgeon. As biologists learn more about shortnose sturgeon, the opportunity to improve water quality and modify dams will likely lead to the long-awaited recovery of this remarkable fish.

Questions After Watching the Video:

1. All the shortnose sturgeon that are netted get permanent identification tags injected into their bodies, but only a few are fitted with radio transmitters. Why use permanent ID tags for all, but only a few radio transmitters?

2. Do the biologists have to catch the sturgeons fitted with the transmitters to collect information? Why or why not?

3. The feeding, overwintering and spawning grounds for shortnose sturgeon seem to be chosen for their characteristics of depth, bottom material and other abundance of food. What are some human-caused disturbances that could potentially adversely affect these areas?

4. Although it takes a shortnose sturgeon 5-8 years to reach sexual maturity and females breed only every 3-7 years, they do lay a huge number of eggs, about 150,000 per fish. Why doesn’t this lead to a large number of adult sturgeon in the Connecticut River?

Field Trips: Holyoke Fish Lift, Holyoke, MA (May-June) Silvio O Conte Anadramous Fish Research Station, Turners Falls, MA Northfield Mountain Environmental Center, Northfield, MA   Curriculum Resources: Bandolin, Larry et al.1995. Final Action Plan and Environmental Impact Statement for theSilvio O. Conte National Fish and Wildlife Refuge. Turners Falls, MA: US Fish & Wildlife Service. To Order: 413-863-0209. (H) Fishways Curriculum Guide. 1993. Northfield Mountain. Northeast Utilities. Call 413-659-3714. Includes great info on the CT River dams, anadramous fish and history of restoration. (H) Ranger Rick’s NatureScope. 1987. Endangered Species: Wild & Rare. Published by the National Wildlife Federation, Washington, DC. (H) (Includes an overview of extinction, habitat destruction and species loss; environmental pollution and problems affecting species; recovery efforts and an appendix of key words and resources. Grades 6-8) Wright, Alexandra. 1992. Will We Miss Them? Endangered Species. Charlesbridge Publishers, Watertown, MA. Grades 6-8. (H)   Video Extension: NOVA’s The Great Wildlife Heist. 60 minutes. WGBH, 1994. Explores the illegal traffic of rare and endangered birds that has become a business worth at least $2 billion a year worldwide. Available through WGBY’s Lending Library: 800-639-8879.   Reading: Look at Your Fish, By Samuel H. Scudder Samuel H. Scudder (1837-1911), a naturalist who specialized in the study of insects, wrote this amusing account for a Boston literary journal in 1873. He tells of enrolling at Harvard’s Lawrence Scientific School, and of his first lesson under the inspired teacher and popularizer of science, Louis Agassiz (1807-1873), then Professor of Natural History. After hours of detailed but unpatterned observation, Scudder let his problem incubate during an evening away from the laboratory, and suddenly was able to combine his individual observations into an important general inference. It was more than fifteen years ago that I entered the laboratory of Professor Agassiz, and told him I had enrolled my name in the Scientific School as a student of natural history. He asked me a few questions about my object in coming, my antecedents generally, the mode in which I afterwards proposed to use the knowledge I might acquire, and finally, whether I wished to study any special branch. To the latter I replied that, while I wished to be well grounded in all departments of zoology, I purposed to devote myself especially to insects. "When do you wish to begin?" he asked. "Now," I replied. This seemed to please him, and with an energetic "Very well!" he reached from a shelf a huge jar of specimens in yellow alcohol. "Take this fish," he said, "and look at it; we call it a haemulon; by and by I will ask what you have seen." With that he left me, but in a moment returned with explicit instructions as to the care of the object entrusted to me.

This web page made possible in part by a grant from the Massachusetts Department of Environmental Management Greenways and Trails Demonstration Grant Program & the Silvio O. Conte National Fish and Wildlife Refuge Challenge Cost Share Program, 1997.