How lipid content and temperature affect American shad (Alosa sapidissima) attempt rate and sprint swimming: implications for overcoming migration barriers

How seasonal effects, such as temperature increases and reduced lipid content affect the ability of anadromous fish to traverse high-velocity barriers and sprint swimming is poorly understood. Here we evaluate American shad (Alosa sapidissima) swimming performance in a flume against high flow velocities (2.5-3.7 m·s−1) during the upstream migration period (April-May; temperatures 11.1-21.4⁰ C) to determine how their willingness to enter a velocity barrier (attempt rate) and swimming endurance changed during migration. American shad did not make attempts at low temperatures, and attempt rate gradually increased throughout the migration as temperatures warmed. American shad displayed two distinct non-sustained swimming modes (prolonged and sprint swimming) and endurance was different between sexes. Females swam at prolonged speeds more often at warmer temperatures and displayed a lower endurance at warm temperatures for long fish. Male swimming was primarily at sprint speeds and was affected by swimming spe...