Population biology of gaper (horse) clams, Tresus capax and T-nuttallii, in southern British Columbia, Canada

Growth anti mortality rates, and densities of gaper (horse) clams, Tresus c apax and T. nuttallii, were estimated from several areas in southern Britis h Columbia (B.C.). Growth rates of T. capax from low intertidal and subtida l zones were greater than those From mid intertidal zones reported in other studies in B.C. Growth rates for T. nuttallii varied between areas. Mean n atural mortality rates for adult T. capax were .15 to .20 from Seal Island, and fur adult T. nuttalli were .44 from Ritchie Bay and .20 from Klaskino Inlet. Densities and biomass of T. capax were higher in the low intertidal zone than the subtidal zone at the Seal Island study area and for T. nuttal lii in the subtidal at Richie Bay. The relative abundance of T. capax and T . nuttallii in the subtidal varied considerably between locations.