. Bulletin. Science; Natural history; Natural history. 1976 INFLUENCE OF TIDES AND WAVES ON G RUN ION 199 earlier workers to be controlled by tides (Thomp- son, 1919: Clark, 1925). After analyzing nu- merous grunion runs, Walker (1949) hypothesized that the timing of runs is set by the initiation of sex product maturation at the second preceding moon phase days from the mid-point of a run series. Walker's thorough study, although never published in its entirety, led to successful predictions of Cali- fornia grunion runs (Walker, 1952). Since these studies, nothing has been published on th
. Bulletin. Science; Natural history; Natural history. 1976 INFLUENCE OF TIDES AND WAVES ON G RUN ION 199 earlier workers to be controlled by tides (Thomp- son, 1919: Clark, 1925). After analyzing nu- merous grunion runs, Walker (1949) hypothesized that the timing of runs is set by the initiation of sex product maturation at the second preceding moon phase days from the mid-point of a run series. Walker's thorough study, although never published in its entirety, led to successful predictions of Cali- fornia grunion runs (Walker, 1952). Since these studies, nothing has been published on the period- icity of grunion runs. Our studies on the Gulf of California grunion, L. sardina. began in 1968. We have attempted to elucidate some of the factors in- fluencing the periodicity of grunion runs by com- paring runs of another species in a different tidal and wave regime. METHODS From 1968 to 1973, L. sardina runs were observed along the beaches of El Golfo de Santa Clara, Sonora, Mexico, in the northern Gulf of Cali- fornia. Data on 53 runs were compiled and timing of each run was compared with the moon phase and the time and height of the tides before, during and after each run. [These data may be obtained from the senior author upon request]. In many instances, observers watched for runs prior to and after a predicted run series to determine the num- ber and intensity of runs in a series. All runs in a series were used in the calculations of mean values. Since tide information was unavailable for the El Golfo de Santa Clara region, runs were compared with tide predictions for Puerto Pefiasco, Sonora (Thomson, 1968-73). Observations show that the Puerto Pefiasco tides are approximately syn- chronous with those of El Golfo although slightly less in amplitude. Spawning behavior of Gulf grunion during night and day runs was observed, filmed with 16 mm and Super-8 mm cameras and compared with that of the California grtmion. The duration of the spawning act and the period
Size: 1718px × 1454px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, booksubjectnaturalhistory, booksubjectscience
