Annual Movements of Shortnose and Atlantic Sturgeons in the Merrimack River, Massachusetts
暂无分享,去创建一个
Abstract We used biotelemetry to study the movements of 23 adult shortnose sturgeons Acipenser brevirostrum and 23 subadult Atlantic sturgeons Acipenser oxyrhynchus oxyrhynchus in the lower 46 km of the Merrimack River between 1987 and 1990. Shortnose sturgeons used two freshwater reaches and one saline reach annually. Sexually mature fish began moving upriver from freshwater wintering areas to a spawning site in April, when increasing river temperature reached about 7°C and decreasing river discharge reached about 570 m3/s. Following spawning in late April–early May, fish moved downriver either to a freshwater reach where they remained all year or farther downriver to a saline reach where they remained for up to 6 weeks. After fish used the saline reach, they returned upriver to fresh water. Atlantic sturgeons entered the river from coastal waters by mid–late May, when increasing river temperatures reached 14.8–19.0°C and decreasing river discharge reached 303–675 m3/s, occupying a saline reach with 0.0–...