Use of Dual‐Frequency Identification Sonar to Monitor Adult River Herring in a Small Coastal Stream

Kevin Magowan,Diane Murphy,Joshua Reitsma

doi:10.1080/19425120.2012.730916

Abstract

AbstractA standard dual‐frequency identification sonar (DIDSON) was deployed in the Herring River, Harwich, Massachusetts, for 3 d in late April 2011 to capture video‐like images of migrating adult river herring (alewife Alosa pseudoharengus and blueback herring Alosa aestivalis). Images recorded 24 h a day were used to manually count and assign species based on DIDSON images of fish size, shape, and behavior. From these counts, the run size was estimated to be 1,976–2,059 individuals during the study. At first, river herring often hesitated to swim through the sample area where the weirs and DIDSON were deployed; however, they eventually did pass, often multiple times. This unique hesitation behavior complicated counting efforts, though it was beneficial to discerning species using DIDSON images. In addition, extremely shallow water upstream of the study site, lack of tree cover, and a high threat of avian predation likely contributed to river herring milling activity at the study site. By providing many clear images of river herring, DIDSON proved to be an effective type of sonar with which to monitor and count river herring continuously in a small coastal stream.Received January 19, 2012; accepted July 30, 2012

Highlights

The primary objective of this project was to assess the ability of dual-frequency identification sonar (DIDSON) to monitor migrating anadromous alewife Alosa pseudoharengus and blueback herring Alosa aestivalis in a small Massachusetts coastal stream
STUDY AREA AND TIMING The two study sites chosen were in the Herring River, which drains 24 km2 of eastern Cape Cod, Massachusetts (USGS Water Resources 2011), and has a population of river herring which return to spawn annually in the ponds that feed the river
Visual Species Identification and Fish Behavior River herring often hesitated to swim through the sampling area where the weirs and DIDSON were deployed

Summary

Introduction

The primary objective of this project was to assess the ability of dual-frequency identification sonar (DIDSON) to monitor migrating anadromous alewife Alosa pseudoharengus and blueback herring Alosa aestivalis (collectively known as “river herring”) in a small Massachusetts coastal stream. The second study site was located above the level control dam and fishway structure at the outlet of Hinckleys Pond, approximately 10.5 river kilometers from Nantucket Sound (Figure 4). This site was selected to determine whether DIDSON could image upstream-migrating river herring as they exited the fishway into Hinckleys Pond. Monitoring at this site facilitated comparison with visual counts, as it was easy to visually count the fish passing into the lake through the concrete pond outlet

Objectives

Methods

Results

Conclusion