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 she patrolled north of Kiska Island, stated she had been attacked by a Japanese destroyer and had fired torpedoes at her with inconclusive results. She operated off Kiska throughout July and sank two enemy patrol boats as she waited for enemy shipping. On 30 July, the submarine reported intensive antisubmarine activity and was ordered back to Dutch Harbor. The "Grunion" was never heard from again. Air searches off Kiska were fruitless, and on 5 October the "Grunion" was reported overdue from patrol and assumed lost with all hands. Her name was stricken from the Naval Vessel Register on 2 November