The cost of publishing this paper was defrayed in part by the payment of page charges. Under postal regulations, this paper therefore must be hereby marked advertisement solely to indicate this fact.
This investigation is a portion of a thesis presented by Dale W. Rush in partial fulfillment of the requirements for the PhD degree.
We acknowledge with appreciation the support of this research by the National Sea Grant Program, U.S. Department of Commerce and the National Science Foundation. We thank D. L. Fredrickson, C. H. Hand. Jr., D. B. Kelley, J. D. Norlyn C. M. Rick, and R. A. Richards for their assistance.