MARTIN, K.L. ; JOHNSON, P.B.; ROBBINS, E.A.; HERNANDEZ, J.A.; SPEER, T.M.; POMMERENING, R.C.; CARPENTER, K.A.; FLANNERY, J.A.; Pepperdine Univ. ; Pepperdine Univ.; Pepperdine Univ.; Pepperdine Univ.; Pepperdine Univ.; Pepperdine Univ.; Pepperdine Univ.; Pepperdine Univ.: Long Walks on Moonlit Beaches: Monitoring Grunion Runs in California
Grunion runs are part of the cultural heritage of southern Californians. These surfing silversides spawn out of water in spectacular summer runs on sandy beaches around midnight. Grunion runs occur at predictable times and dates associated with the highest nighttime tides from April to July. These marine fish are presumed to remain near shore at other times, but are rarely taken in trawls or by any standard fish population assessment methods. Prior to 2001, grunion populations had not been monitored for over 50 years. Because they oviposit at high tide, their eggs incubate out of water, buried in the sand of some of the most heavily used urban beaches in this populous area. In 2001, uncertainty about the grunion population status in San Diego prompted an outpouring of citizen concern regarding the possible effects of mechanized beach grooming on grunion nests, and a call for data by the city. We developed a protocol for training volunteers to attend predicted runs at specific times and locations, and to report their sightings via an interactive web data acquisition form. With the help of hundreds of volunteers, we monitored 10 sites on San Diego beaches for the past three years. Volunteers saw large numbers of grunion spawning in many locations on the city shoreline. Spawning activity peaked in late April and late May in all three years. The duration of the runs and numbers of fish varied significantly between sites and over the season, indicating that monitoring must be done consistently and extensively to characterize this ephemeral yet charismatic species. In 2004 our volunteers surveyed grunion in California from San Diego to Monterey Bay. Funded by NOAA Grant NA06RG0142, Calif. Sea Grant R/CZ-94PD, NFWF, and NSF-DBI 99-87543.
