Meeting Abstract
Famous for unique spawning behavior, California Grunion Leuresthes tenuis surf onto sandy beaches to lay eggs out of water. This endemic silverside fish, found only off California and Baja California, shares critical spawning habitat with millions of beach goers along one of the world’s most heavily populated coastlines. Spawning occurs during spring and summer, the times of heaviest human use. Although regulations offer some protection, anthropogenic impacts include a recreational fishery with bare-handed catching. Natural predators from land and sea prey on the distracted fish flopping on shore. The stock cannot be assessed with traditional fisheries methods, so evaluation of population status and trends is difficult. For over a decade, the spawning runs have been monitored across the habitat range with the help of citizen scientists, the Grunion Greeters. Greeters provide evaluation of the runs and other ecological features, including the incidence of animal predation and recreational fishing on the runs. Within this long term dataset, we compared runs with and without natural predators, and with and without human hunters. We found that humans disturbed the runs more than animal predators did, and that the number of humans chasing fish can be far higher than the number of natural predators at a beach during the run. In the presence of active human hunting, runs were smaller, although human observation without attempts to catch fish did not appear to disturb the runs. Highly efficient human hunting sometimes removed every fish that appeared on shore, in effect stopping the run and preventing any successful reproduction. Additional conservation efforts may be necessary, including catch-and-release and no-take reserves, to protect this vulnerable endemic species from overharvest.
