Migratory Delay of Anadromous River Herring at Anthropogenic Obstacles on a Small Coastal Stream

Restricted access to spawning habitat is one of the primary factors contributing to population declines of anadromous river herring (genus Alosa). Hydroelectric dams, tide gates, and road-crossing culverts often disrupt migrations of diadromous fishes. Acoustic (JSATS) and PIT telemetry were used to quantify migratory delay of river herring at a tide gate and an additional five consecutive road-crossing culverts on the Herring River in Wellfleet, MA. Data were collected for three seasons from 2014-2016. Return rates of repeat spawners exceeded 15% in 2015. Median upstream delay at the tide gates was seven days after first arrival. Both upstream and downstream groundspeed were reduced by an order of magnitude through road-crossing culverts compared to between culvert reaches. Passage success decreased and mortality increased for fish arriving later in the season. These data demonstrate the importance of considering movement rates in barrier assessments and evaluations.