Grunion shrimp. An isopod, two species of flies, sandworms, and a beetle have been found preying on the eggs. Some shorebirds such as egrets and herons prey on grunion when the fish are on shore during spawning. Seagulls, sea lions, and larger fish such as sand sharks have also been observed feeding on grunion during a grunion run. The reduction of spawning habitat due to beach erosion, harbor construction, and pollution is believed to be the most critical problem facing the grunion species. Despite local concentrations, the grunion is not an abundant species. While the population size is not known, all
USS Grunion the Pacific on 24 May. A week later, as she transited the Caribbean Sea for Panama, she rescued 16 survivors of the USAT "Jack", which had been torpedoed by the , and conducted a fruitless search for 13 other survivors presumed to be in the vicinity. Arriving at Coco Solo on 3 June, the "Grunion" landed the survivors and continued on to Pearl Harbor, arriving on 20 June. Departing Hawaii on 30 June after ten days of intensive training, the "Grunion" touched Midway Island before heading toward the Aleutian Islands for her first war patrol. Her first report, made as