NON-RANDOM, SEASONAL OSCILLATIONS IN THE ORIENTATION AND LOCOMOTOR ACTIVITY OF SEA CATFISH (ARIUS FELlS) IN A MULTIPLE-CHOICE SITUATION

¹ Department of Biology, Texas A&M University, College Station, Texas 77843

A quantitative analysis of angular orientation and locomotor activity of 80 sea catfish (Arius felis) over 12 consecutive months, under controlled conditions of photoperiod, temperature, and water quality, revealed non-random oscillations in the monthly mean orientation vectors and monthly mean activity of the experimental population. Marquardt modeling of monthly mean activity and of the sine and cosine components of monthly mean orientation indicated significant annual, bimodal cycles for all three variables. These cycles correlated with the observed, seasonal inshore-offshore migrations of A. felis, as documented in the literature, and had significant periods of 11.40, 5.11, and 6.64 months for the sine and cosine components of orientation and for activity, respectively. Photoperiod alone apparently acted as the exogenous cue triggering these cyclic changes in orientation and activity.