Evaluation of a Gastric Radio Tag Insertion Technique for Anadromous River Herring

—Anadromous river herring (alewives Alosa pseudoharengus and blueback herring A. aestivalis), which constitute a historically and ecologically important component of coastal rivers, have declined precipitously throughout the Atlantic seaboard. Suggested causes of river herring decline include commercial fishing and predation by striped bass Morone saxatilis. Although the causes of this recent trend are poorly understood, river herring are especially vulnerable to adverse impacts during their spring spawning migration. Radiotelemetry is an especially useful method for addressing potential problems encountered during the movement of these fish from the ocean to freshwater. In spite of frequent calls for evaluation of telemetry methods, controlled tests of posttagging effects are rare for alosids and virtually nonexistent for anadromous river herring. We developed a protocol for gastric tagging of anadromous river herring, and we used hatchery and field studies to evaluate behavior, tag placement, stress response, and posttagging mortality. We also compared tagger effects and quantified posttagging upstream movements of fish in the field. In controlled hatchery trials, no fish died at 10 min, 1 h, or 14 d posttagging. No tags were rejected, and only 1 of 35 tags ruptured the gut. In field cages, mortality, plasma cortisol, glucose, and chloride measured at 24 h were similar between tagged and untagged fish. In the field, 12 of 14 fish moved upriver after tagging and spent 114 h on average at upriver sites. Using a variety of approaches, we found no evidence that our tagging protocol adversely affected river herring in comparison with untagged fish that were subjected only to handling and holding. Our protocol, evaluated by comparing responses of tagged and untagged fish under controlled conditions, may be useful in future studies that seek to understand causes of decline for anadromous river herring. Anadromous fish provide recreational and commercial fishing opportunities; serve as an ecological link between freshwater, estuarine, and coastal food webs (Salia et al. 1972; Willson and Halupka 1995); and are components of many coastal watershed restoration and management programs. Anadromous river herring, the collective term for two closely related and jointly managed species (alewife Alosa pseudoharengus and blueback herring A. aestivalis; Collette and KleinMcPhee 2002), have historically been important in rivers along the midand North Atlantic coast of North America. Recently, anadromous river herring populations have declined precipitously. In response to this crisis, the National Oceanic and Atmospheric Administration designated the alewife and blueback herring as species of concern (NOAA 2007), and several Atlantic states (including Massachusetts, Rhode Island, Connecticut, North Carolina, and Virginia) have instituted a moratorium on the harvest and possession of river herring (MDMF 2005; RIDEM 2006; CDEP 2007; NCDENR 2007; VDGIF 2007). Beal (1981) suggested * Corresponding author: [email protected] Received May 6, 2008; accepted September 10, 2008 Published online April 9, 2009 367 North American Journal of Fisheries Management 29:367–377, 2009 Copyright by the American Fisheries Society 2009 DOI: 10.1577/M08-111.1 [Article]