摘要
In the present work we integrate the available quantitative information on the following aspects of the Hellenic Seas: (a) distribution of temperature and salinity, water masses, currents and climate change; (b) distribution of oxygen and nutrients in coastal and open sea waters; (c) plankton abundance, production and assemblages; (d) benthic abundance, diversity and assemblages; (e) fish abundance, diversity, assemblages, biology and population dynamics; and (f) fisheries catch trends and variability, wholesale value of catches, catch-effort relationship and catch species composition for 1964-89. Such an integration may possibly form an ecological basis for the management of the Hellenic and Eastern Mediterranean resources. The available chemical and biological data clearly indicate the highly oligotrophic nature of the Hellenic waters. However, within this oligotrophic environment relatively eutrophic areas do exist. Thus, nutrient concentrations as well as plankton and benthos abundance and/or productivity are all by one order of magnitude higher in the N-NW Aegean Sea than in the Ionian and S-SE Aegean Seas, with the latter area being one of the most oligotrophic areas of the world ocean. Similarly, fish catch densities decline from 2.13 km−2 in the N-NW Aegean Sea, to 0.62 km−2 in the S-SE Aegean Sea. The factors responsible for such a differentiation are also discussed. The available data also show that Hellenic fisheries resources, especially the demersal and inshore ones, are overfished. This is the result of the increased fishing effort, the intense modernization of the Hellenic fleet, and the inadequacy of the technical managerial measures currently in use (e.g. closed seasons, minimum mesh size regulations, minimum landing sizes, effort limitations). The latter is mainly attributed to the multi-gear and multi-species nature of the Hellenic fisheries that poses certain difficulties in designing and implementing uniform protective measures, particularly so for the demersal and inshore fisheries. The managerial measures currently in use should be either replaced or complemented by the creation of marine harvest refugia, which provide a refuge in space rather than a refuge in numbers, the latter being the aim of most traditional fisheries management measures.