Low Juvenile Pinto Abalone Haliotis kamtschatkana kamtschatkana Abundance in the San Juan Archipelago, Washington State

Abstract

To investigate contemporary pinto abalone Haliotis kamtschatkana kamtschatkana recruitment events and juvenile abundance, 66 abalone recruitment modules (ARMs) were deployed at two depths and three sites in the San Juan Archipelago (Washington State) that were historically inhabited by substantial abalone populations. Based on published studies from California and British Columbia, ARMs are proven tools for surveying juvenile pinto abalone abundance. Abalone recruitment modules provide complex habitat and protection from predation. The ARMs were surveyed in situ for juvenile abalone abundance six times over the course of 26 months. Only eight abalones were observed, including three juveniles that were less than 50 mm (shell length). The mean density of juvenile abalones inhabiting the ARMs across all three sites during the 2006 surveys was 0.012/m². The absence of juvenile abalones within the ARMs, combined with sharp regional declines in adult pinto abalone abundance, suggests limited local recruitment of this species, which is currently designated as threatened in Canada and as a species of concern in the USA.

Received January 24, 2011; accepted May 25, 2011

ACKNOWLEDGMENTS

We thank the WDFW Central Shellfish dive team, B. Sizemore, M. Ulrich, T. Blewett, L. Hillier, and O. Eveningsong for their help during dive surveys as well as use of their research vessel. We are grateful to the University of Washington Friday Harbor Laboratories, D. Duggins, and P. Kitaeff for the use of dive vessels and facilities throughout this project. We also thank C. Jackels, B. Eastham, D. Hamm, and N. Wight for diving and boat tending contributions and R. Saito, T. Ewing, R. Cruz, B. Scott, C. Burge, and R. Strenge for their help constructing ARMs. We gratefully acknowledge P. Plesha and M. Rust, the National Oceanic and Atmospheric Administration Mukilteo Research Station and T. Rogers, School of Aquatic & Fishery Sciences, University of Washington for the use of facilities and equipment during ARM construction. We would also like to acknowledge J. Lessard, B. DeFreitas, and B. Allen for insight on juvenile abalone survey methods. This research was funded, in part, by a grant from the Washington Sea Grant Program, National Oceanic and Atmospheric Administration, U.S. Department of Commerce, under grant number NA04OAR4170032, project number R/F-150 to C.S.F. and the School of Aquatic and Fishery Sciences at the University of Washington. Funding was also provided by the American Academy of Underwater Sciences, the WDFW, and the School of Aquatic and Fishery Sciences at the University of Washington.