Butler et al Mullibeam sonar mapping techniques for estimates of Haliotis sorenseni 



531 



rent levels, juveniles were observed on extremely rare 

 occasions (Owen^). Thus, the absence of small individu- 

 als during ROV observations does not rule out recent 

 recruitment to this population. Consequently, although 

 recruitment in the last three years may be undetect- 

 able, recruitment from the last three decades should be 

 evident in our surveys. 



Conclusions 



The use of detailed sonar mapping techniques has proven 

 to be an invaluable method to estimate amounts of dif- 

 ferent habitat types for the purposes of quantifying 

 marine organisms within their specific habitat. Specifi- 

 cally, white abalone restoration efforts would be greatly 

 enhanced by more surveys incorporating high-resolution 

 bathymetric maps that would serve to better define the 

 characteristics of suitable white abalone habitat. Our 

 concept of what a viable white abalone population is 

 would benefit from more accurate density estimates for 

 other areas within the historic range and from a better 

 understanding of how white abalone are distributed 

 within populations. 



The ultimate goals of recovery and eventual removal 

 of white abalone from the Endangered Species List de- 

 pends upon establishing confidence in the demographic 

 parameters that define a viable white abalone popula- 

 tion. It has become apparent that conducting studies 

 such as this one, with continuing efforts to improve 

 sample standardization techniques over time, is critical 

 to achieving recovery goals. 



Acknowledgments 



Multibeam sonar mapping during the 2002 cruise was 

 funded by the National Fish and Wildlife Foundation 

 through a grant to the California Department of Fish 

 and Game. Dan Richards provided data from the 1999 

 Channel Islands National Park white abalone survey. 

 John Wagner, Anthony Cossio, Ben Maurer, Scott Mau, 

 and David Murfin piloted the ROV and provided tech- 

 nical support. The officers and crew of the RV David 

 Starr Jordan ran transects and survey lines. Chuck 

 Oliver participated in cruises and, along with Nancy 

 Lo, designed the microhabitiat analyses. Pat lampi- 

 etro, Carrie Bretz, Kate Thomas, Jason Mansour, Tif- 

 fany Van, Andrew Rapp, Bryan Jones, Josh Sampey, 

 and Saori Zurita helped with multibeam sonar data 

 acquisition, processing, and analysis. David Murfin, 

 Lara Asato, and several anonymous reviewers pro- 

 vided comments that improved earlier versions of this 

 manuscript. 



■* Owen, B. (abalone fisherman). 2001. 

 P.O. Box 601, Gualala, CA 95445. 



Personal commun. 



Literature cited 



Allee, W. C. 



1931. Animal aggregations: a study in general soci- 

 ology. Univ. Chicago Press, Chicago, IL. 



Babcock, R., and J. Keesing. 



1999. Fertilization biology of the abalone Haliotis laevi- 

 gata: laboratory and field studies. Can. J. Fish. Aquat. 

 Sci. 56(91:1668-1678. 



Behrens M. D., and Lafferty K. D. 



2005. Size frequency measures of white abalone, impli- 

 cation for conservation. In Sixth California islands 

 symposium (D. K. Garcelon and C. A. Schwemm, eds.), 

 p. 427-432. Institute for Wildlife Studies, Ventura, 

 CA. 



Cochrane, G. R., J. L. Butler, and G. E. Davis. 



2005. Refining estimates of potential white abalone 

 habitat at northern Anacapa Island California using 

 acoustic backscatter data. In Benthic habitats and the 

 effects of fishing (P. W. Barnes and J. P. Thomas, eds.), 

 p. 161-164. Am. Fish. Soc, Bethesda, MD. 



Cochrane, G. R., and K. D. Lafferty. 



2002. Use of acoustic classification of sidescan sonar data 

 for mapping benthic habitat in the northern Channel 

 Islands, California. Cont. Shelf Res. 22:683-690. 



Davis, G. E.. P. L. Haaker, and D. V. Richards. 



1996. Status and trends of white abalone at the Cali- 

 fornia Channel Islands. Trans. Am. Fish. Soc. 125(1): 

 42-48. 



1998. The perilous condition of white abalone, Hali- 

 otis sorenseni, Bartsch, 1940. J. Shellfish Res. 17(3): 

 871-875. 



Elliott, J. M. 



1977. Some methods for the statistical analysis of samples 



of benthic invertebrates. Freshw. Biol. Assoc. Sci. Publ. 



25:1-150. 

 Freeman, S. M., and S. I. Rogers. 



2003. A new analytical approach to the characterization 

 of macro-epibenthic habitats: linking species to the 

 environment. Estuar. Coast. Shelf Sci. 56:749-764. 



Geiger, D. L. 



1999. Distribution and biogeography of the recent Hali- 

 otidae (Gastropoda: Vetigastropodai worldwide. Boll. 

 Malacologico. 35(5-12):57-120. 



Greene, G. H., M. M. Yoklavich, R. M. Star, V. M. O'Connel, 

 W. W. Wakefield, D. E. Sullivan, J. E. McRea, and G. M. 

 Cailliet. 



1999. A classification scheme for deep seafloor habi- 

 tats. Oceanol. Acta 22:683-690. 



Hobday, A. J., and M. J. Tegner. 



2000. Status review of white abalone Haliotis sorenseni 

 throughout its range in California and Mexico. NOAA 

 Tech. Memo. NMFS-SWR-035, 101 p. 



Hobday, A. J., M. J. Tegner, and P. L. Haaker. 



2001. Over-exploitation of a broadcast spawning marine 

 invertebrate: decline of the white abalone. Rev. Fish 

 Biol. Fish. 10:493-514. 



lampietro, P. J., R. G. Kvitek, and E. Morris. 



In press. Recent advances in automated genus-specific 

 marine habitat mapping enabled by high-resolution 

 multibeam bathymetry. Mar. Technol. Soc. J. 



Jenness, J. 



2002. Surface areas and ratios from elevation grid, 

 vers. 1.2 for ArcView 3.2. Jenness Enterprises, Flag- 

 staff, AZ. 



