ECOLOGY OF THE SHEEPSGOT RIVER ESTUARY 



In 1954 the Atlantic salmon research of 

 the U.S. Fish and Wildlife Service was oriented 

 to include a study of the ecological complex in a 

 salmon river and its estuary. The project has 

 been coordinated with the regular activities of 

 State and Federal agencies concerned with the 

 study of certain estuarine species and has been 

 concentrated in a single river, the Sheepscot, 

 near Boothbay Harbor, Maine . 



Cooperating on this project are the Clam 

 Investigations, the Atlantic Herring Investigations, 

 and the Atlantic Salmon Investigations of the U.S. 

 Fish and Wildlife Service; and the Department of 

 Sea and Shore Fisheries, the Department of In- 

 land Fish and Game, and the Atlantic Salmon 

 Commission of the State of Maine. 



The Sheepscot River was selected as a 

 suitable study area as it was convenient to a well - 

 equipped fishery laboratory in Boothbay Harbor 

 where personnel of four of the cooperating agen- 

 cies were stationed; in addition, studies were 

 already in progress on several economically 

 important species in that area, such as herring, 

 alewife, smelt and clams. 



The Sheepscot River itself is not an im- 

 portant salmon stream, but it does support 

 small natural runs of these fish and is regularly 

 stocked with hatchery-reared young. 



The purpose of the present report is to 

 give a comprehensive description of the study 

 area to provide a background for other more 

 detailed reports covering specific problems. 

 It will also serve to complement the report of 

 Bryant (1956) which described the fresh -water 

 part of the river. 



Methods and materials 



A series of stations was first established 

 where regular observations were to be made, 

 (fig. 1). Water samples were collected at these 

 stations with a Kemmerer sampling bottle. 

 Salinities were determined by titration with 

 silver nitrate according to Knudsen's method 



(Oxner, 1920) and, where less accuracy was 

 permissible, by means of specially calibrated 

 hydrometers. Temperatures were taken with a 

 mercury thermometer directly in the sampling 

 bottle. As the time required to raise the bot- 

 tle from the deepest water sampled was only a 

 few seconds, change in temperature within the 

 bottle was disregarded. 



Plankton was collected by two methods: 

 vertical hauls from bottom to surface with a 

 1/2 -meter #2 silk plankton net and four -minute 

 surface tows with a Clarke -Bumpus plankton 

 sampler equipped with a #10 silk net. Currents 

 were measured according to a method described 

 by Pritchard and Burt (1951), in which a weighted 

 current cross is suspended at various depths 

 and the wire angles resulting from the drag of 

 the current are measured to compute the direc- 

 tion and velocity of current. 



Fish were collected by means of gill nets 

 and seines of several sizes, traps, fyke nets, 

 and a small otter trawl. Intertidal invertebrate 

 populations were sampled by removing a 0.1 M 

 quadrat from the sediment to a depth of 10 centi- 

 meters . The material was then sieved through 

 a 14 X 16 mesh-per-inch plastic screen. Sub- 

 tidal populations were sampled with a 0. 1 m2 

 Petersen -type grab and similarly sieved. These 

 procedures were supplemented by numerous 

 field observations and hand collections. A 

 counting weir was constructed near the head -of - 

 tide in the river to obtain information on the 

 movements of salmon and other anadromous fish. 

 Stomach analyses were made on numerous fish 

 and some birds to aid in the study of certain 

 food relationships. 



Geography 



The Sheepscot River is a stream of mod- 

 est size L/ which originates in the low uplands 



between the Penobscot and Kennebec valleys and 

 flows generally southward to the Gulf of Maine . 



)J A description of the river proper may be 

 found in Bryant, 1956. See list of literature cited. 



