Interspecific differences in the distribution of adult and juvenile ponyfish (Leiognathidae) in the Gulf of Carpentaria, Australia

The distribution of leiognathids was investigated at 261 sites spread throu ghout the Gulf of Carpentaria. Eight species, Gazza minuta, Leiognathus dec orus, L. equulus, L. fasciatus, L. leuciscus, L. smithursti, L. splendens a nd Secutor ruconius, were usually restricted to coastal areas, whereas four species, L. bindus, L. moretoniensis, Leiognathus sp. and S. insidiator, w ere not. Two other species, L. aureus and L. elongatus, were caught at only one site each. The relationships between size of fish and depth in Albatro ss Bay were investigated by examining the mean weight and minimum and maxim um lengths of different species in 356 trawls. Six of the coastal species s howed the common pattern of linear increase in size with depth. This patter n is consistent with the existence of estuarine and/or inshore nursery area s, and supports previous observations of these species. In contrast, three of the widespread species exhibited approximately quadratic relationships b etween size and depth. This unusual pattern resulted from small fish living in both the shallow inshore areas and deeper offshore areas, and it may re duce competition among the juveniles of the large number of very abundant, coexisting species of leiognathid.