Appendicularians (Chordata, Tunicata) in the diet of anchovy Engraulis anchoita in the Argentine Sea

CAPITANIO, F.; PAJARO, M; ESNAL G. B.

SCIENTIA MARINA

INST CIENCIAS MAR BARCELONA

Año: 1997 vol. 61 p. 9 - 15

0214-8358

Stomach contents of 321 Engraitlis anchoiru adults were studied together with plankton samples taken simultaneously from two cruises, one carried out in Buenos Aires Province waters (34"-40"s) and the other in North Patagonian waters (41"-44"s). Stomach contents from the first cruise were dominated by Appendicularia and Copepoda and, to a lesserextent, bivalve postlarvae, anchovy eggs, Cladocera, Salpidae, Euphausiacea ancl Amphipoda. The stomach repletion stages used indicated that appendicularians were an iinportant food for anchovy; appeiidicularians have never been previously mentioned in anchovy diet. North Patagonian anchovies contained mainly Copepoda ancl Cladocera along with Appendicularia, Euphausiacea, anchovy eggs and Amphipoda. For each survey, the abundance of appendiculaiians in both the plankton and stomach contents showed similar patterns. Tlie oniy species of Appendicularia recorded was Oikople~iro clioica. In plankton, 50% of the animals were mature. However, in the stomachs they were al1 mature. Probably tlie anchovy has filtered on breeding aggregations of mature houseless individual grouped near the suiface for spawning explaining tlie great number of non-digested individiials in the stomachs.Engraitlis anchoiru adults were studied together with plankton samples taken simultaneously from two cruises, one carried out in Buenos Aires Province waters (34"-40"s) and the other in North Patagonian waters (41"-44"s). Stomach contents from the first cruise were dominated by Appendicularia and Copepoda and, to a lesserextent, bivalve postlarvae, anchovy eggs, Cladocera, Salpidae, Euphausiacea ancl Amphipoda. The stomach repletion stages used indicated that appendicularians were an iinportant food for anchovy; appeiidicularians have never been previously mentioned in anchovy diet. North Patagonian anchovies contained mainly Copepoda ancl Cladocera along with Appendicularia, Euphausiacea, anchovy eggs and Amphipoda. For each survey, the abundance of appendiculaiians in both the plankton and stomach contents showed similar patterns. Tlie oniy species of Appendicularia recorded was Oikople~iro clioica. In plankton, 50% of the animals were mature. However, in the stomachs they were al1 mature. Probably tlie anchovy has filtered on breeding aggregations of mature houseless individual grouped near the suiface for spawning explaining tlie great number of non-digested individiials in the stomachs.