Fisheries oceanography and the ecology of early life histories of fishes: a perspective over fifty years

Abstract

SUMMARY: Fisheries oceanography can be defined as the study of the ecology of fishes in the ocean: so defined, it comprises study at all levels of ecological organization-organisms, populations, communities, and ecosystems. The early life history of fishes plays out at each of these levels of organization. A paradigm developed by Johan Hjort at the turn of the twentieth century, along with postulates by Hjort and many of his colleagues that followed, came to guide much of fisheries oceanography through the ensuing hundred years. Research themes that address these postulates can be roughly partitioned as the study of the physiological ecology of the eggs and larvae of fishes in the sea, and the study of the abundance and distribution of fish propagules. Using case studies of organisms and physical processes, considerable progress has been made in understanding the causes of variation in population recruitment, defined either by stage-based models and simulated by individual-based models. Some of this progress has been published in Scientia Marina, or its predecessor Investigación Pesquera. The causes of variation, however, are interactive and operative at differing, yet often overlapping, spatial and temporal scales. Difficulty in matching spatial scales that typically differ by an order of magnitude or more, will continue to trouble the resolution of causes of population recruitment. Moreover, study of the causes of variation in recruitment has not led to predictive power at an annual scale. Prediction at a decadal scale, using community (or more appropriately larval fish assemblages) and ecosystem level dynamics, is more hopeful. -La oceanografía pesquera puede ser definida como la ecología de los peces en el océano: definida de este modo, comprende el estudio a todos los niveles de organización ecológica: organismos, poblaciones, comunidades y ecosistemas. Los primeros estadios de desarrollo de los peces intervienen en cada uno de estos niveles de organización. El paradigma desarrollado por Johan Hjort a principio de siglo veinte, junto con postulados posteriores del propio Hjort y muchos de sus colegas, han servido de guía de la oceanografía pesquera de los siguientes cien años. Los temas de investigación a que conducen estos postulados pueden ser fundamentalmente divididos en el estudio de la ecología fisioló-gica de los huevos y larvas de peces en el mar y el estudio de la distribución y abundancia de los propágulos. Utilizando el estudio de casos particulares de organismos, se han conseguido considerables progresos en la comprensión de las causas de variación en el reclutamiento de las poblaciones, definido ya sea por los modelos basados en el estadio de desarrollo o en simulaciones basadas en el individuo. Algunos de estos avances han sido publicados en Scientia Marina, o en su predecesora Investigación Pesquera. No obstante, las causas de variación son interactivas y operativas a escalas espaciales y temporales distintas, o incluso solapadas. La dificultad para ajustar las escalas espaciales que típicame...

Feeding on protists and particulates by the leptocephali of the worm eels <i>Myrophis</i> spp. (Teleostei: Anguilliformes: Ophichthidae), and the potential energy contribution of large aloricate protozoa

“…This energy contribution, while small when compared with the total, daily energy requirement of leptocephali, indicates that these large protozoa can be physiologically substantial for several reasons: because they are likely to be consumed continuously throughout the feeding period of leptocephali; because the overall energy demand of metamorphic worm eels is low; because energy (matter) for growth is provided by the transformation GAG into morphological (structural) components; and because GAG supplies much of the energy for metabolism. The importance of large protozoa, including ciliates that lack lorica, in the diets of leptocephali and other larval fishes, should be assessed comprehensively (Govoni, 2005). The survival of eels through early life might be compromised by any decline in the availability of large protozoa as food for elopomorph leptocephali.…”

Composition and structure of the larval fish community in the NW Iberian upwelling system during the winter mixing period

“…In coastal upwelling regions, the surface offshore and onshore Ekman flows associated with coastal upwelling and downwelling, respectively, are also important in larval fish distribution (Parrish et al 1981, Norcross & Shaw 1984. Other abiotic and biological factors, such as water temperature , Olivar et al 2010, the spawning location and spawning strategy of adult fishes (Parrish et al 1981, Norcross & Shaw 1984, the vertical distribution (John & Re 1995, Olivar & Sabatés 1997) and the vertical migratory behaviour (Parrish et al 1981, Paris & Cowen 2004) of fish larvae and trophic interactions (Govoni 2005, Olivar et al 2010) also play a role. In consequence, processes and factors that influence the horizontal distribution, survival and abundance of fish larvae would also define the horizontal structure of the larval fish community (LFC).…”

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“…According to Gucu and Gucu (2002), this case occurs as a result of Posidonia meadows existence in the mentioned region. As a conclusion, understanding the ichthyoplankton structure and dynamics of an area is important to comment on fish populations of there (Govoni, 2005). Therefore, it is thought that more specific and detailed investigations are required about the ichthyoplankton of the Northeastern Coasts of Mediterranean.…”

“…The data about the early stages of fishes are informative on the ichthyology, fisheries oceanography, aquaculture and ecology in some respects such as the researching of fish communities, identifying of spawning times and localities, estimating of stock biomass, examining of recruitment (Demir and Southward, 1974;Reay, 1984;Palomera and Pertierra, 1993;Begg, 2005;Govoni, 2005). Thus, the importance of the ichthyoplankton surveys results from the fact that they can provide mentioned data faster, cheaper and reliable.…”