Martín D. Ehrlich

The reproductive biology of Pinguipes brasilianus Cuvier, 1829 (Osteichthyes: Pinguipedidae) in temperate rocky reefs of Argentina

Pinguipes brasilianus is a conspicuous and abundant rocky-reef fish inhabiting the Northern Patagonian gulfs of Argentina, Southwest Atlantic. This study describes its reproductive biology in this region. We made macroscopic and histological descriptions of the testis and ovary development, analyzed the evolution of the gonadosomatic index (GSI) in both sexes throughout the year, and estimated fecundity and length at 50% maturity for females. Pinguipes brasilianus is a multiple spawner with indeterminate annual fecundity and an extended reproductive season, encompassing austral spring and summer. Low GSI values in males (monthly means ranged between 0.11% and 0.75%) and low relative fecundity in female fish (between 2 and 44 oocytes/g) are consistent with a need of close proximity between male and female during oocyte fertilization, sexual courtship and with spawning in pairs and/or within reef crevices. The estimated length at 50% maturity (± SD) for females was 15.22 ± 0.43 cm total length. Although P. brasilianus shares the main reproductive features of its congeneric species Pinguipes chilensis , male GSI and female length at 50% maturity in P. brasilianus were markedly lower than those reported for P. chilensis , while relative and batch fecundity were greater in fish of the same size.

Ichthyoplankton Associated to the Frontal Regions of the Southwestern Atlantic

The study region covers a wide latitudinal range, from 22°S to 55°S, and a bathymetric scope ranging from the coast to the shelf-break and adjacent region to a depth of ca. 1000 m. Hydrography of the region is extremely complex. Oceanographic structures are diverse, including several estuaries, water masses, wind systems, tidal regimes, and two major oceanic currents. A significant portion of the biological production is related to the existence of several marine fronts, characterized by different forcing, and temporal and spatial scales. Fish species that inhabit the region are diverse, covering a range of life strategies. Among those fishes that produce eggs and/or planktonic larvae, there are estuarine, shelf and oceanic forms, and species characteristic of tropical/subtropical or subantarctic waters. Pelagic species are more important in the northern part, while demersal species dominate the southernmost area. The region looks like an intricate mosaic of opportunities for life cycle closure of distinct species. Marine fronts seem to be the preferred areas to establish spawning and nursery grounds by fishes, and current knowledge allow to identify the elements of Bakun’s triad for several of those fronts.

Early life history of the Argentine sea bass (Acanthistius patachonicus) (Pisces: Serranidae)

1 Centro Nacional Patagónico (CENPAT) Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) Boulevard Brown 2915 Puerto Madryn Chubut, U9120ACD Argentina 2 Instituto Nacional de Investigación y Desarrollo Pesquero (INIDEP) P.O. Box 175 Mar del Plata Buenos Aires, B7602HSA Argentina 3 Instituto de Ecología, Genética y Evolución de Buenos Aires (IEGEBA) CONICET Facultad de Ciencias Exactas y Naturales Universidad de Buenos Aires (UBA) Intendente Güiraldes 2160 Ciudad Universitaria Ciudad Autónoma de Buenos Aires, C1428EGA Argentina