Laserfiche WebLink
Zone usage was not uniform. Distribution of contacts for the 10 large bonytail <br />demonstrated that site fidelity was high and significant {X2 ='697.93, df = 25, P < <br />0.001). Usage was nil or low in more than half the zones -- no signals were ever <br />contacted within 7 zones (B; C, D, E, K, L and O) and only one or two contacts in <br />each of 8 zones A, F, H, M, N, V, Y and Z (Table 3 and Fig. 2). Five zones had <br />moderate usage (5 to 15 contacts each; zones G, P, Q, R and S) and six zones <br />had high use (19 or more contacts each, up to a maximum of 63; zones I, J, T, U, <br />W, X). The six highest use zones occurred in three nearest-neighbor pairs <br />separated by one or more low use zones. <br />Generally, once most fish established "residency," those individuals returned <br />each morning to the same zone, often to the same exact location, within the high <br />levee (see Fig. 3). A few fish switched from consistent use of one area to <br />consistent use of another (e.g., Fig. 3, BT666 and BT777). <br />Nonetheless, we only had information on the 10 marked fish. Other, unmarked <br />individuals may have occupied "empty" zones or been present in the same zones <br />as the marked fish. Habitat differences were not obvious to us, and the high <br />levee appeared relatively uniform from zones A to Z. We thus assume other <br />bonytail, perhaps many, occupied interstices within the high levee. <br />Perhaps more striking than the consistent high use of certain -zones was the <br />apparent fidelity of individual fish for specific zones. Most-fish were found with <br />much higher frequency in only one or two zones, with occurrences in other zones <br />being limited to only one or a few observations (Table 3 and Fig. 3). Two or <br />more fish rarely occupied the same zone at the same time, although different fish <br />may have occupied the same zone on different occasions. <br />Directional Data. There were 2,947 separate recorded bearings; 1,648 and <br />1,299 observations were made from the high and river levee listening stations, <br />respectively. A total of 508 of 945 simultaneous paired readings fell within the <br />800 m listening station radius: 161 (16.1 contact per 15-minute period) during <br />dusk (1945-1000), 269 (11.2 contacts per period) during mid-hours (2215-0315), <br />and 78 (7.8 contact per period) during dawn hours (0330-0545). These results <br />are consistent with the pattern of signal detections observed in the field across all <br />contacts -most fish made an appearance shortly after sunset during the dusk <br />period, numbers typically were reduced by one-to-a few during the mid-hours, <br />and signals representing all remaining individuals disappeared as fish returned to <br />the high levee. <br />Directional data applied almost exclusively to fish activity during periods of <br />darkness because marked individuals spent the daylight hours under cover <br />provided by interstices of the high levee. Number of paired, simultaneous <br />contacts averaged 50.8 per fish and varied among individuals from 0 to 112 <br />(Table 1). Few contact intersections fell within the pond, and interpretation of <br />geographic pattern was based only on the general position of signals (e.g., <br />5 <br />