Movement of Sacramento sucker, Catostomus occidentalis, and California roach, Lavinia symmetricus, in a Mediterranean-climate stream

The movements of aquatic organisms are poorly understood but have important ecological consequences. We studied fish movements of Sacramento sucker (Catostomus occidentalis) and California roach (Lavinia symmetricus) in Strawberry Creek, a small Mediterranean-climate creek flowing through Berkeley, California. Our study aims to quantify weekly-scale movements, including distance and direction, over the summer low flow season. We hypothesized that long-distance movements would decrease as water levels decrease following the summer. Moreover, we hypothesized that several check dams along the creek would act as barrier for upstream movements of suckers and roach. To test these hypotheses, we captured 130 suckers and roach along a 1km stretch in July, marked them with uniquely coded passive integrated transponder (PIT) tags and released to the area initially captured. We then resurveyed the creek to track the locations of individual fish using a portable antenna, which allowed us to quantify movement between weeks. When fish were detected, we also measured environmental variables (e.g., water depth) to test for statistical correlations between fish presence and habitat characteristics. Overall, we expect a positive correlation between distance moved and water level. We also expect no upstream movements past check dams, though we expect that fish will be able to move downstream the dams. Our study will contribute knowledge on the movements of two common stream fishes and highlight the influence of Mediterranean-climates on fish movement patterns. Moreover, our results will be useful for future restoration efforts aimed at conserving fish populations in this urban creek.