FISHERY BULLETIN: VOL. 78, NO. 4 



more upon wind and current movements rather 

 than habitat preference. 



Throughout our study A. lyolepis and H.jagua- 

 na clearly dominated the numerical component 

 of the surf zone ichthyofauna; however, differences 

 in the rank of the remaining species did occur. 

 Gunter (1958) suggested that intraseason species 

 abundance in the surf zone of Mustang Island 

 changed annually, although T. carolinus and H. 

 jaguana were generally present in considerable 

 numbers. Reid (1956) observed that the greater 

 number of the surf zone ichthyofauna along the 

 Texas coast, with the exception oiB.patronus , was 

 similar during successive summers. Star drum, 

 Stellifer lanceolatus, was considerably more 

 abundant during the second summer as were T. 

 carolinus, M. littoralis, and M. americanus. Dur- 

 ing the first simimer of a 3-yr study, Schaefer 

 (1967) observed butterfish, Peprilus triacanthus , 

 as the numerically dominant species within the 

 surf zone of Fire Island, N.Y. In the remaining two 

 summers of his study, northern puffer, Sphoeroi- 

 des maculatus, was the most numerous species. 



Factors Affecting Occurrence 



The dominant factors affecting the abundance 

 of fishes within the surf zone of Horn Island were 

 tide level, time of day, and temperature. The fre- 

 quency of engraulids and clupeids was closely as- 

 sociated with time and tide. However, during the 

 summer sampling periods, when fish abundance 

 was greatest in the early morning, tide levels were 

 also highest. Consequently, the effect of the two 

 factors is difficult to separate. Subsequent re- 

 search (Ross unpubl. data) indicates that both may 

 be important, although Roessler (1970) found that 

 the frequency of H. jaguana collected from south- 

 ern Florida was not significantly related to tidal 

 fluctuation. Seasonal changes in temperature ap- 

 peared to be of most importance in affecting the 

 frequency of T. carolinus and M. littoralis. 



The pronounced daily variation in occurrence 

 of the most abundant fishes (i.e., A. lyolepis, 

 A. hepsetus, and H. jaguana) indicates that they 

 are not as permanently associated with the surf 

 zone habitat as the gulf kingfish and the Florida 

 pompano. Diel catch rates showed that engraulids 

 and clupeids largely moved out of the surf zone 

 during the day, whereas, the gulf kingfish and 

 Florida pompano exhibited little change in daily 

 abundance. Predator avoidance may be an impor- 



tant reason for the high early morning densities of 

 the clupeoid fishes. 



Other studies have also documented the influ- 

 ence of time of day and tidal cycle on fish abun- 

 dance in surf areas. Merriman (1947) found that 

 shore zone fishes in Connecticut had activity pat- 

 terns associated with tide level. The greatest 

 number of fishes occurred during high tide when 

 fish appeared to be actively feeding. Daly (1970) 

 also described daily activity patterns in anchovies 

 collected along south Florida beaches. Anderson et 

 al. (1977) suggested that temperature was the 

 primary factor affecting fish abundance along a 

 South Carolina beach; however, diel changes were 

 not investigated, de Sylva et al. (footnote 3) also 

 found that temperature was the greatest factor in 

 determining frequency of most fishes, whereas sa- 

 linity was secondary in importance and turbidity 

 had little effect. The importance of temperature 

 and salinity to the abundance and distribution of 

 fishes has been discussed in depth by Gunter 

 (1938, 1945, 1950, 1957) and to some extent by 

 Warfel and Merriman (1944). Warfel and Merri- 

 man reported that the greatest and lowest number 

 of fishes appeared relative to high and low temper- 

 atures, but that no direct correlation could be 

 made. Gunter (1945, 1957) suggested that temper- 

 ature was the dominant factor in initiating sea- 

 sonal migrations and other cyclic activities of 

 fishes along the Texas coast. The interaction of 

 wind direction (i.e., inshore winds) with tempera- 

 ture may further increase the number of fishes in 

 the Horn Island surf zone. 



In summary, the Horn Island surf zone is 

 utilized primarily by H. jaguana, A. lyolepis, A. 

 hepsetus, M. littoralis, and T. carolinus. There is 

 strong seasonal periodicity with the greatest 

 abundance in spring and summer, as well as daily 

 fluctuations due to tide level and time of day. Since 

 the individuals of the above species were primarily 

 late larval and juvenile forms, the importance of 

 surf zone habitats as nursery and refuge areas for 

 certain species should be recognized. 



ACKNOWLEDGMENTS 



We wish to express our appreciation to Kathleen 

 Clark and John Baker for their consistent will- 

 ingness to assist in the field. We are also indebted 

 to Harriet Perry and her staff at the Gulf Coast 

 Research Laboratory for the use of their facilities 

 and equipment, and to the National Park Service 

 for allowing us to collect on Horn Island. Wind 



920 



