The reproductive success of aquatic animals depends on a complex web of relationships between the environment, the attributes of the reproductive individuals and human-induced selection. All of them are manifested directly or indirectly through parental effects, which can also compensate for certain external impacts. Parental effects refer to the influence that the phenotype and environmental conditions in which individuals develop exert on the phenotype of their offspring, and they can even have transgenerational impact. This paper describes the different types of parental effects and reviews the published literature to analyze the causes of their variation and their impact on reproductive resilience and population dynamics.

Se analizaron los desplazamientos de los cardúmenes de merluza común Merluccius hubbsi en el área de desove de Patagonia antes del comienzo de la puesta y durante una temporada reproductiva. Se describieron los cambios de abundancia, composición de sexos, estructura de tallas y localización de los desoves. Durante octubre y noviembre, los cardúmenes de merluza migraron desde aguas más profundas hacia la costa, aproximadamente a los 44°S, donde tiene lugar la puesta en diciembre. Durante enero las principales agregaciones reproductivas permanecieron cerca de la costa (50 m de profundidad) pero desplazadas hacia el sur (45°S); en febrero la intensidad del desove disminuyó y las hembras en post-puesta comenzaron a retornar a aguas más profundas. En general, este proceso fue completado primeramente por los desovantes más jóvenes (35-45 cm LT), los cuales tienen una temporada reproductiva más corta que las hembras de mayor edad. Los machos arribaron más temprano al área de puesta y permanecieron durante más tiempo que las hembras. Durante el período reproductivo se observaron variaciones espaciales en la proporción de sexos, que fueron atribuidas a: 1) segregación local producida por el comportamiento reproductivo de la merluza, donde varios machos se agrupan con una hembra al momento de la puesta, y 2) migración de hembras en post-puesta hacia aguas más profundas, lo cual origina mayor proporción de machos en las áreas costeras

Morphometrical and histological techniques were employed to characterize Pagrus pagrus larvae nutritional condition. Larvae were reared in laboratory under controlled conditions with the main objective of testing whether these methodologies allowed finding differences between larvae from different feeding treatments. Once yolk was consumed (three days after hatching) larvae were assigned to a feeding treatment: starved during the whole experiment; delayed feeding, starved during three days; fed during the entire experiment. Algae (Nannochloropsis oculata) and rotifers (Brachionus plicatilis) were provided to larvae for feed treatments. Larvae were fixed daily; for morphometrical purposes in 5% formaldehyde solution, and in Bouin for histological sections. Results herein obtained showed that both methodologies are sensitive enough to distinguish larvae characterized by different nutritional condition states obtained from the feeding treatments. Consequently, these methodologies could be employed in wild red porgy larvae in order to asses their nutritional condition. These techniques could also be employed to check larval quality obtained with aquaculture purposes to estimate the effects of changes in rearing protocols or kind of food supply and thus, to guaranty a higher survival of early developmental stages of reared larvae.

The reproductive biology of southern blue whiting (Micromesistius australis) inhabiting waters of the southwest Atlantic Ocean (52°‐53°S and 57°‐62°W) was studied through histological analysis of the ovaries. During 2003, the spawning peak occurred at the beginning of September south of the Malvinas Islands. Batch fecundity of this species ranged from 35 000 (41 cm total length, TL) to 245 000 (62 cm TL) oocytes and relative batch fecundity was 122 ± 43 (Mean ± SD, n = 24) oocytes per gram somatic weight. The average proportion of mature females with stage‐0 post‐ovulatory follicles was 0.25 for September 2003, which indicated a spawning frequency of 4 days during the peak of the season. Large females produced more egg batches than small spawners during the same period, but no significant relationship was found between oocyte dry weight and female size of southern blue whiting.