Se describen doce taxa de condrictios fósiles provenientes de rocas asignadas al Plioceno Superior de la Formación Horcón, región de Valparaíso, Chile central; se discuten sus registros previos, implicancias paleobiogeográficas y paleoambientales. La fauna comprende Callorhinchus sp., Heterodontus sp., Carcharodon carcharías, Isurus oxyrinchus, Galeorhinus galeus, Carcharhinus brachyurus, Hexanchus griseus, Squatina sp., Pristiophorus sp., Rajidae, Dasyatidae y Myliobatidae. Esta es una de las asociaciones de condrictios más diversas del Neógeno Tardío de Chile y del resto de América del Sur.

The interaction of melting glaciers and oceanic stormy weather produce a large variability in the water column structure of the coastal sea from the south Pacific coast of Patagonia. This area is largely utilized as spawning and nursery ground for the mesopelagic fish Maurolicus parvipinnis (Sternoptichyidae) during the austral spring. Using microstructure analysis of sagittal otoliths and fluctuating asymmetry of M. parvipinnis larvae from 4.0 to 11.4 mm standard length (SL), we studied the spatial distribution, the variation of larval condition and recent growth during October–November 2009 between 50°06′ and 52°45′S. Hydrographic conditions varied between 1.4 and 9.5°C, 14.6–33.5 units of salinity, 11.5–26.5 units of sigma-t and the stability ranged from 3.6 to 594 cycles h⁻¹. Larval abundance ranged between 3.1 and 293.7 ind. 10 m⁻², with the highest abundance associated with channels connecting fjords and the adjacent ocean. Larvae grew at a rate of 0.174 mm day⁻¹, and those individuals collected in areas with intermediate water column stability (216–270 cycles h⁻¹) showed greater body condition, measured as recent otolith growth index (ROGI). However, these larvae had a similar departure from ideal symmetry (FA1 residual model) as larvae collected in more stratified or well-mixed areas. Overall, larvae showed size-dependent asymmetry, sagittal otoliths of smaller larvae (< 7 mm SL) being more asymmetrical than those of large larvae (P < 0.05). This suggests that M. parvipinnis larvae may be experiencing the impacts of water column variability differently, as well as other ecological interactions at different larval stages. Thus, water column structure at hatching would be important for the survival of this fish inhabiting the Patagonian fjords of southern Chile.

The distribution and the growth of larval rockfish Sebastes capensis were studied during two oceanographic cruises carried out in a sector of the Chilean fjords (43°30′S–46°S) during spring 2002 (November) and winter 2003 (August). Abundance (up to 600 per 10 m2) of pre- and post-flexion larvae was higher during the austral spring than in winter (20 per 10 m2). Larvae were smaller principally above the halocline in the first 50 m of the water column throughout the channels and fjords; in contrast, post-flexion larvae were more abundant seawards and were totally absent in the freshest waters. Analysis of the otoliths indicated that larvae between 3.3 and 12.2-mm standard length collected during November grew 0.15 mm d−1. Additionally, it showed that older larvae from the outer part of the channels and over the shelf laid down wider otolith increments than larvae found in the interior waters, coinciding with the area of greatest abundance of larger calanoid copepods. Ontogenetic differences in distributions suggest that different habitats are utilized during the early life stages of S. capensis, and that they seem to be shared with several other Sebastes species. However, the mechanisms for transport in different areas vary widely, making the question of the evolutionary forces driving these ontogenetic changes in distribution even more intriguing.

The feeding ecology of larvae of the lightfish Maurolicus parvipinnis (Pisces: Sternoptychidae, 2.8–13.4 mm) in fjords and channels of southern Chile (41°–53°S), was analysed during austral spring 2005, 2008 and 2009. Larvae of M. parvipinnis begin external feeding at ∼3-mm body length (BL). They are carnivorous predators with similar feeding incidence during day and nighttime, but with higher prey numbers in their guts during day than night. Feeding incidence increased after 8-mm BL, coinciding with an increase in the growth rate of the upper jaw length. The diet of M. parvipinnis larvae was composed of 22 different prey items, mainly invertebrate eggs, nauplii, calanoid, cyclopoid and poecilostomatoid copepodites, ostracods, cladocerans and amphipods. According to the relative importance index [%index of relative importance (IRI)], the most important prey items were Paracalanus parvus copepodites (%IRI = 55.6%), Oithona spp. copepodites (%IRI = 16.3%) and copepod eggs (%IRI = 9.2%), indicating that most of the feeding is on copepod early life stages. Trophic niche breadth was ∼0.17 and it did not increase with larval length, suggesting that larval M. parvipinnis have a high degree of selective foraging. Also, we detected a significant relation between feeding success and vertical stratification of the water column, with higher prey volume per gut found in larvae collected in areas with a Brunt-Väissälä frequency of 0.07–0.2 cycles s⁻¹. We discuss potential effects of the fjord environment on the feeding behavior of this important species along Chilean Patagonia.