Effects of predation on the distribution of shrimp in Western Port Bay, Victoria

This study investigated the influence of predation on the distribution of shrimp in Western Port Bay from July 1977 to January 1980. Predation by birds was determined by analysing the diets and feeding rates of the most abundant wading birds in the area, the Royal Spoonbill (Platalea regia), the White-faced Heron (Ardea novaehollandiae), and the Sacred Ibis (Threskiornis aethiopica). Predation by fish was determined by examining the gut contents of fish caught in the beam trawls. The shrimps found in the gut contents were identified and, where possible, sexed and carapace length measured.

This study found that the major consumers of shrimps were the scorpaenid, Gymnapistes marmoratus (Australian Cobbler) and the short-headed worm-eel, Muraenichthys breviceps. The Royal Spoonbill feed almost solely on M.intermdieum, whereas the other 2 species of waders feed mostly on infauna. The larger-sized individuals, which tend to be females, are subject so higher predation pressure than other groups within species.