Ichthyoplankton distribution and feeding habits of fish larvae at the inshore zone of northern Patagonia, Chile.

The Inland Sea of Chiloé is a semi-enclosed sea of northern Patagonia characterized by freshwater inputs from a fjord in the north and high influence of offshore waters in its southern sub-basin. The zone has been referred to as an important fish nursery ground. In order to assess its relevance as a spawning ground and the strategies for temporal coexistence of larvae of fish species from diverse origins in these inshore waters, we investigated both the horizontal and vertical distributions, and the feeding habits of early stages of fish during the period of highest productivity (austral spring). Ichthyoplankton richness and abundance were higher in the northern sub-basin, dominated by the offshore midwater lightfish Maurolicus parvipinnis, and the shelf-break and demersal hake Merluccius gayi. The larvae of the coastal rockfish Sebastes oculatus and the clupeid Strangomera bentincki were more abundant in surface waters, while the larvae of Merluccius australis, M. gayi, and M. parvipinnis reached deeper waters. The co-occurring inshore larvae of M. gayi, M. parvipinnis, and S. oculatus preyed actively at day and night times on a wide spectrum of zooplankton sizes, with the small calanoid copepods being the most commonly consumed food items in the largest larvae of M. parvipinnis and M. gayi. Nauplii were frequent food items for smaller larvae of M. parvipinnis, S. oculatus, and S. bentincki. The high spring productivity and the large abundances of potential zooplanktonic prey, along with larval spatial segregation, are visualized as the main factors enabling species with different origins to co-inhabit and grow at inshore waters in northern Patagonia.