Environmental Biology of Fishes

, Volume 66, Issue 3, pp 279–291

The Influence of Environmental Variables on the Distribution and Abundance of Three Elasmobranchs in Tomales Bay, California


DOI: 10.1023/A:1023907121605

Cite this article as:
Hopkins, T.E. & Cech, J.J. Environmental Biology of Fishes (2003) 66: 279. doi:10.1023/A:1023907121605


We tested the hypothesis that temperature, salinity, and dissolved oxygen affect elasmobranch distribution and abundance in Tomales Bay, California, with monthly longline samples over a 20 month period. We used a Poisson regression under generalized least squares and found that temperature and salinity were the most important factors determining the distribution and abundance of the three most common elasmobranch species, bat ray, Myliobatis californica, leopard shark, Triakis semifasciata, and brown smoothhound shark, Mustelis henlei. Females of all three species were more abundant than males throughout the Bay, and were most abundant in the warmer, more saline inner bay. All three species apparently left Tomales Bay in late fall as water temperatures in the bay decreased to <10–12° C, and returned in early spring after temperatures increased to > 10° C. Three of 257 bat rays tagged in Tomales Bay were recaptured, all within 1 km of their tagging location despite having been free for up to 583 d.

bat rayMyliobatisleopard sharkTriakisbrown smoothhoundMustelus

Copyright information

© Kluwer Academic Publishers 2003

Authors and Affiliations

  1. 1.Department of Wildlife, Fish, and Conservation BiologyUniversity of California, DavisDavisUSA
  2. 2.US Fish and Wildlife ServiceSouth Florida Ecological Services OfficeVero BeachUSA