Safety of Strontium Chloride as a Skeletal Marking Agent for Pacific Salmon

Abstract

The purpose of this study was to evaluate the biological effects associated with administering strontium chloride as a marking agent to age-0 Chinook Salmon Oncorhynchus tshawytscha fry. Fish were held in a 0× (0 mg/L), 1× (3,000 mg/L; current standard dosage), 3× (9,000 mg/L), or 5× (15,000 mg/L) solution of strontium chloride for 72 h (three times the standard duration of 24 h). The mortality among fish in the 5× strontium chloride exposure group was significantly higher than that observed in the other groups. A dose-related effect on general fish behavior and on feeding behavior was observed. Fish in all test tanks appeared to feed to satiation, except for fish in the 5× tanks during days 2 and 3. Fish in all other test tanks behaved normally. No dose-related effect on fish growth was detected. Histopathological evaluations showed that fish in the 5× exposure group had a significantly higher number of gill lesions than the 0× group. Our mortality, behavioral, and histological assessments suggested that juvenile Chinook Salmon could be safely immersed for three consecutive days in a 9,000-mg/L solution of strontium chloride. This finding potentially expands the present 1,000–3,000-mg/L dosage and 24-h holding period that can be used to mark juvenile fish with strontium chloride solutions. The research also provides necessary target animal safety data for U.S. Food and Drug Administration approval of strontium chloride as an alternative marking method that is suitable for fish with a short holding time.

Received February 19, 2017; accepted July 16, 2017 Published online September 22, 2017

ACKNOWLEDGMENTS

We thank the New York State Salmon River Fish Hatchery for providing the age-0 Chinook Salmon fry used in this study. Multiple personnel from Cornell Animal Resources and Education assisted with preparation of standard operating procedures and forms prior to the study; Marty Slade and all of the histology technicians at the AHDC (Cornell University College of Veterinary Medicine) allowed us to perform fish health evaluations of test fish; Joe Ebel and Joseph Hillebrandt at the AHDC Toxicology Section assayed water samples to determine strontium chloride concentrations; and Denise Archer was the quality assurance officer based at the AHDC. We are grateful to Leonard Orr for his assistance in calibrating several of our instruments and to Doug Haner for his invaluable help with VMC Aquatics Facility maintenance. The statements, findings, conclusions, views, and recommendations in this paper are those of the authors and do not necessarily reflect the views of any organization. This work was performed under an animal use protocol approved by the Institutional Animal Care and Use Committee at Cornell University. The FDA Center for Veterinary Medicine’s Minor Use and Minor Species Grant Program (Grant Number FD005066) supported the research reported in this paper. The content is solely the responsibility of the author(s) and does not necessarily represent the official views of the FDA Center for Veterinary Medicine.