Scaling Acoustic Telemetry of Bluefish in an Estuarine Observatory: Detection and Habitat Use Patterns

Abstract

AbstractWe telemetered adult bluefish Pomatomus saltatrix via a fixed estuarine hydrophone array to assess estuarine habitat use and determine the feasibility of using this approach coastwide. Eighteen bluefish (286‐622 mm fork length) were surgically implanted with ultrasonic tags transmitting at either 2‐s or 5‐s intervals. The fish were monitored during their stay within a temperate estuary by hydrophones and associated environmental data loggers at major bottlenecks. They moved quickly through the hydrophone detection ranges, with 3‐100 acoustic contacts being recorded within 15‐min intervals. Contacts per 15‐min interval with fixed hydrophones were similar for fish with 2‐s and 5‐s transmission interval tags, but mobile tracking proved ineffectual. Bluefish preferred the shallow polyhaline portion of the estuary, but several moved upriver to a salinity as low as 12‰. The latter occurred near the minimum (14°C) of the temperature range utilized (11‐27°C). Residence times (0‐55 d; mean = 15 d) indicated the importance of estuaries to bluefish during spring and fall. Residence time was unrelated to fish size. The success of a coastwide effort monitoring multiple estuaries for bluefish could be high and would be enhanced by proper configuration of the tags and hydrophone arrays, as outlined here.