The question remains as to how sculpins could potentiallyhave such significant predatory and demographic effects onsockeye salmon spawning on the island beaches when theireffects are usually not considered significant in stream habitats(e.g., Moyle 1977). We believe the answer lies in the largesubstrate on the island beaches. Leonetti (1997) reported geometricmean particle sizes between 35 and 79 mm on WoodyIsland and Fuel Dump Island spawning beaches, with particlesof <13 mm virtually absent (0.6%). Given that sculpins canpenetrate cobble and gravel with significant interstices (Phillipsand Claire 1966; McLarney 1967; Biga 1996), this poroussubstrate makes the developing eggs susceptible to sculpinpredation while at the same time providing refuge for sculpinsfrom their own predators.
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