Egg and larval amino acid composition as indicators of niche resource partitioning in pelagic fish species

We analysed the amino acid composition (AA) of eggs and larvae of the pelagic fish speciesSardina pilchardus(sardine),Scomber scombrus(mackerel),Trachurus trachurus(horse mackerel) andMicromesistius poutasou(blue whiting) collected along the west Atlantic coast of Spain and from the Cantabrian Sea during March to April 2000. A discriminant analysis showed that it was possible to distinguish each fish species according to the egg and larval AA. Moreover, egg and larval AA varied among different areas within each fish species. From the data of larval abundance obtained from 5 cruises carried out along the northern Spanish coast from 1995 to 2000 (Mph-1995, Sefos-1995, Careva-1998, Jureva-1998 and Seamar-2000), the temporal and spatial overlap among fish species was estimated. There was a significant relationship between larval AA similarity and larval spatial-temporal overlap among fish species, which means that those larval species that had greater spatial and temporal overlap, had a similar larval AA. On this basis, the differences in egg and larval AA within each fish species among different areas seem to be due to differences in habitat conditions; mainly temperature, salinity, and food quality and quantity. We concluded that egg and larval AA could be used as indicators of niche resource partitioning (food resources and spatial allocation) among pelagic fish species.