Abundance and culture trials of Ruditapes philippinarum (Adam and Reeve, 1850), and abundance of Tellina (Quidnipagus) palatum (Iredale, 1929) at two sites in Kāne'ohe Bay,O'ahu,Hawai'i

Abundance, length‐frequencies and distribution of Ruditapes philippinarum (Manila Clams) and Tellina (Quidnipagus) palatum were measured at two beaches in Kāne'ohe Bay, O'ahu, Hawai'i in June, 2010. Abundances had decreased from 866.2 m^?2 to 3.4 m^?2 for Ruditapes and from 75.5 m^?2 to 1.5 m^?2 for T. palatum since 1977. Distribution of both species was patchy, but both were most commonly found >40 m from shore. Size frequencies of live clams compared with empty shells suggest that few Ruditapes survive to sexual maturity. A similar trend was not detected for T. palatum. Aquaculture trials of R. philippinarum were conducted at the He'eia and Moli'i traditional Hawaiian fishponds in the same bay. The clams failed to thrive, although triploid and diploid Crassostrea gigas performed well in concurrent trials in the same fishponds. Current lower abundances for wild R. philippinarum could be due to factors related to predation or nutrient limitations. Previously, two large sewage outfalls existed at the surveyed clam bed areas which may have temporarily increased nutrient availability for both wild and cultured clams. Current nutrient levels may inhibit Manila clam growth and recruitment in Kāne'ohe Bay.