MiDDAUGH, D. P., AND M. J. HeMMER. 



1984. Spawning of the tidewater silverside, Menidia penin- 

 sula (Goode and Bean), in response to tidal and lighting 

 schedules in the laboratory. Estuaries 7:139-148. 



MiDDAUGH, D. P., AND T. TAKITA. 



1983. Tidal and diurnal spawning cues in the Atlantic silver- 

 side, Menidia menidia. Environ. Biol. Fishes 8:97-104. 

 Miller, C. A., J. M. Wilson, and A. H. Meier. 



1981. Induction of semilunar rhythms of reproductive indices 

 \n Fundulus grandis. [Abstr.] Am. Zool. 21:995. 

 National Oceanic and Atmospheric Administration. 



1981. Tide tables 1982, high and low water predictions, East 

 Coast of North and South America including Greenland. 

 U.S. Dep. Commer., 235 p. 

 Newmann, D. 



1978, Entrainment of a semilunar rhythm by simulated tidal 

 cycles of mechanical disturbance. J. Exp. Mar. Biol. Ecol. 

 35:173-185. 



Ross, R. M. 



1983. Annual, semilunar, and diel reproductive rhythms in the 

 Hawaiian labrid Thallassoma duperrey. Mar. Biol. (Berl.) 

 72:311-318. 

 Saigusa, M. 



1980. Entrainment of a semilunar rhythm by a simulated 

 moonlight cycle in the terrestial crab, Sesarma haemntocheir. 

 Oecologia (Berl.) 46:38-44. 

 Taylor, M. H., and L. DiMichele. 



1980. Ovarian changes during the lunar spawning cycle of 

 Fundidus heteroclitus. Copeia 1980:118-125. 



1983. Spawning site utilization in a Delaware population of 

 Fundulus heteroclitus (Pisces: Cyprinodontidae). Copeia 

 1983:719-725. 

 Taylor, M. H., D. DiMichele, and G. J. Leach. 



1977. Egg stranding in the life cycle of the mummichog, 

 Fundulus heteroclitus. Copeia 1977:397-399. 

 Taylor, M. H., L. DiMichele, M. M. Levitan, and W. F. Jacob. 



1979. Lunar spawning cycle in the mummichog, Fundulus 

 heteroclitus (Pisces: Cyprinodontidae). Copeia 1979:291- 

 297. 



Thrall, T., and L. Engelman. 



1981. Univariate and bivariate spectral analysis. In W. J. 

 Dixon (editor), BMDP statistical software, p. 604-638. Univ. 

 Calif. Press, Los Ang. 



Waas, B. p., and K. Strawn. 



1983. Seasonal and lunar cycles in gonadosomatic indices and 



spawning readiness of Fundulus grandis. Contrib. Mar. 



Sci., Texas A&M Univ. 26:127-141. 

 Weisberg, S. B. 



1981. Food availability and utilization by the mummichog, 

 Fundulus heteroclitus (L.). Ph.D. Thesis, Univ. Delaware, 

 Newark, 104 p. 



Weld, M. M., and A. H. Meier. 



1982. Circadian gonadal responses to daily disturbances in 

 gulf killifish. [Abstr.] Am. Zool. 22:866. 



Anson H. Hines 



Kenric E. Osgood 



Joseph J. Miklas 



Smithsonian Environmental Research Center 

 P.O. Box 28 

 Edgewater, MD 21037 



UNDERSEA TOPOGRAPHY AND 



THE COMPARATIVE DISTRIBUTIONS OF 



TWO PELAGIC CETACEANS 



Prey species are not uniformly distributed. Foraging 

 efficiency, therefore, should be maximized when ef- 

 fort is concentrated in areas where prey are concen- 

 trated. Cetacean food is probably most concentrated 

 in regions of high general productivity. Because the 

 undersea topography may be a major influence on 

 productivity, cetacean foraging patterns may be 

 associated with the topographic patterns of the 

 ocean floor (Hui 1979). I report here the occurrences 

 of two species of pelagic odontocete cetaceans, the 

 Pacific pilot whale, Globicephala Tnacrorhyrwhus, 

 and the common dolphin, Delphinus delphis, relative 

 to seafloor topography and to diet. Although it is not 

 clear if the genus Delphinus in this region is com- 

 posed of two species or one species with two sub- 

 species, the vast majority are Delphinus delphis 

 (Banks and Brownell 1969; Evans 1975). If data 

 from more than one species are included in this 

 study, it is assumed that any interspecies difference 

 in distribution relative to substrate was not signifi- 

 cant to the analyses. 



Methods and Results 



This study was conducted in the Southern Califor- 

 nia Continental Borderland (Fig. 1) which consists of 

 ridges, deep troughs, and basins (Chase 1968). There 

 were 61 survey flights totaling 22,353 km. The 

 flights were conducted at various times, all of them 

 during midday (1000-1500) from 1968 through 1976. 

 Totals of 1,057 pilot whales in 38 aggregations (in 

 January, March, April, July, October, and Decem- 

 ber) and 47,105 common dolphins in 142 aggrega- 

 tions (in all months of the year) were observed. The 

 survey methods have been previously described (Hui 

 1979). 



The data for each species were not divided into 

 temporal subsets as in Hui (1979), but were treated 

 as whole sets. The distribution of each species was 

 examined relative to depth and relative to change in 

 depth. The method of analysis has been presented in 

 detail elsewhere (Hui 1979). 



Both pilot whales and common dolphins were 

 distributed uniformly {P > 0.10) throughout the 

 depth classes but not uniformly among the Contour 

 Index (CI) classes {P < 0.005). For each species there 

 were more observations than expected over the 

 steepest bottom topography and fewer than ex- 

 pected over the flattest (Table 1). 



I also compared the distribution of pilot whales 



472 



FISHERY BULLETIN: VOL. 83, NO. 3, 1985. 



