Planktonic Production Cycles and their Relationship with Fishing Resources on the Portuguese Coast

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The “Ciclos de Produção Planctónica e Sua Relação com os Recursos Pesqueiros” project aims to describe the dynamics of planktonic communities associated with the coastal upwelling system in Portugal. This description is important for understanding the bio-oceanographic processes that condition posture, growth and survival in pre-recruitment phases, as well as patterns of abundance, distribution and migration of fishery resources, in particular small pelagic species. In addition to this goal, project also aims to determine the areas, seasons and the laying intensity of these species.

The data presented refer to the sampling carried out between 21 August and 3 September 1985 by the N/E "Norway", collected on cruise 02050885. The zooplankton sampling was carried out at 104 stations in an area corresponding to Continental Portugal, defined by the 20 and 1000-meter iso-baitmetrics. The collection of zooplanktonic material was carried out by FAO net - 90 cm in diameter and 505 μm in mesh opening - in oblique trawls according to Smith and Richardson, 1977, from a maximum depth of 200 m to the surface. In stations with depths of less than 200 m, dragging was carried out from the bottom (less than 5 meters) to the surface. The volume of filtered water was determined using a previously calibrated flow meter located within the mouth of the network at a distance of 1/4 of its diameter. The speed of the trawls was about 50 meters per minute, with the total drag time being measured and the cable angles recorded every 10 meters during the ascent of the network.

The objective of the "Zooplankton" line of activity is to study its spatial-temporal variability from the point of view of both biomass and species with a view to contributing to the bio-oceanographic characterization of the sardine distribution area on the Portuguese coast and to create a repository for the identification data and enumeration of zooplankton samples, intended to contribute to the establishment of a zooplankton database on the Portuguese coast and to make it accessible to interested users.

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