Royalty of the River
Kennebec Sturgeon
Kenneth Edgecomb at his commercial sturgeon fishing operation on Sturgeon Island, Merrymeeting Bay, circa 1900. Bath Times photo
Sturgeon, dating back 200 million years, are among the most primitive of the bony fishes. With no internal skeleton, their body surface contains five rows of bony plates, or “scutes.” They are typically large, long-lived fish that inhabit a great diversity of riverine habitat, from the fast-moving freshwater riverine environment downstream and, for some species, into the offshore marine environment of the continental shelf. Sturgeon have been harvested typically for their roe, known as cavier and for their meat.
Merrymeeting Bay and the Kennebec estuary provide spawning and nursery habitat for the large [up to 20’] and threatened Atlantic sturgeon and steady habitat for the endangered shorter [3-4’] shortnose sturgeon. Numbers of sturgeon in the Gulf of Maine are significantly lower than historical levels and have remained so for the past 100 years. The Kennebec/Androscoggin and Bay are probably the only remaining spawning areas in the Gulf of Maine. Originally decimated from overfishing, threats to the species continue from habitat degradation, dredging, accidental capture and potential injury and mortality as “incidental take” in other fisheries. Despite their diminished status, it has become common to see sturgeon leaping from the Bay in the summertime.
Tom Squiers was employed by the Maine Department of Marine Resources (MDMR) for 36 years, retiring in 2009. For many years he directed their Stock Enhancement Division. Squiers’ responsibilities involved the management and restoration of diadromous fish which includes striped bass, American shad, alewife, blueback herring, rainbow smelt, Atlantic sturgeon, shortnose sturgeon, and American eel.
Squires spoke at a meeting of The Friends of Merrymeeting Bay in Brunswick, ME on April 13, 2016. He conducted several studies to assess the status of shortnose sturgeon and Atlantic sturgeon in the Kennebec River. Some of the work he has done includes studies of sturgeon in the Kennebec River in anticipation of the expansion into the river by the Bath Iron Works and the new bridge over the river at Bath. Squiers was a member of the Shortnose Sturgeon Recovery Team which published the Final Recovery Plan for the Shortnose Sturgeon, Acipenser brevirostrum in 1998.
There are more short nose than long nose sturgeon in the Kennebec. Their long lives, 80 years, makes impacts to their lives, habitat and reproduction, which begins at 20 years of age, more significant to the species. More recently tracking data has shown that sturgeon from as far as the Merrimac and Penobscot Rivers are traveling to spawn in the Kennebec River. The reason for this migration is not known.
Below are exerpts from Tom Squires’ talk on 4/13/16 in Brunswick, Maine:
Atlantic Sturgeon
– Acipenser oxyrhinchus
1. Atlantic Sturgeon are anadromous. They spend most of their life cycle in the marine environment but spawn in freshwater.
2. Adults enter the rivers from May through July to spawn, Females are usually over 20 years old and over 6.5 feet in length and males over 12 years old and over 5 feet in length. The spawning interval for males is 1-5 years and 2-5 years for females
3. They spawn in flowing waters at water temperatures ranging from 55-68 ºF and require solid substrate for the eggs, which are adhesive. Temperatures in the Kennebec River during spawning in recent studies ranged from 64 to 77 ºF.
4. After egg deposition, hatching occurs in approximately from 4 to 6 days depending on temperature. They are initially photonegative and seek cover. 5-7 days after hatching they begin swim-up and drift with current. They absorb the yolk sac and begin feeding.
5. Juveniles remain in their natal river system for 2-6 years and 30 to 36 inches in length.
6. Subadult Atlantic sturgeon wander among coastal and estuarine habitats, undergoing rapid growth.
Shortnose Sturgeon
– Acipenser brevirostrum
1. Shortnose Sturgeon are amphidromous. They spend most of their life cycle in the riverine environment.
2. Adults migrate to spawning area from late April through early June to spawn, Females are usually over 12 years old and range from 30 to 40 inches in length and males over 8 years old and 30 to 36 inches in length. The spawning interval for males is 1-5 years and 2-5 years for females 3. They spawn in flowing waters at water temperatures ranging from 46-65 ºF and require solid substrate for the eggs, which are adhesive.
3. Hatchlings are photonegative and seek cover in substrate. Larvae 9-16 days old are photopostive and drift downstream. Larvae most active at night. Prefer deep channels (Richmond and Kynard, 1995).
4. Juveniles (<45 cm) remain in freshwater, feeding on insects and small crustaceans (Dadswell, 1979). Very little is known about the location and habitat of juveniles in the Kennebec River system.
Historical Sturgeon Fishery
The first documented fishery was in 1628 at Pejepscot Falls on the Androscoggin River (Wheeler and Wheeler 1878), and by the early 1700s the sturgeon fishery in the Province of Maine employed more than 20 vessels in some years. In 1849, harvesters took 160 tons of sturgeon from the Kennebec River for roe and oil, but the fishery was discontinued after 1851 when sturgeon became scare A subsequent fishery in the Kennebec began in 1872, but within five years sturgeon were scarce, and by 1880 the catch was about 150 sturgeon (Atkins 1887).
A small commercial fishery on the Kennebec River in South Gardiner occurred near Rolling Dam from June 15 –July 26, 1980. Thirty-one adult Atlantic sturgeon (27 males, 4 of which were ripe and 4 females, 1 of which was ripe) were captured. Two adults tagged in 1978 by the MEDMR in South Gardiner were recaptured in this fishery.
In 1983, Maine closed the tidal waters of the Kennebec and Androscoggin to harvest of sturgeon, and instituted a 72-inch minimum size for other areas. In 1992, the harvest of sturgeon (both species) became illegal in Maine’s coastal waters.