CHARACTERIZATION OF THE EUROPEAN ANCHOVY POPULATION, Engraulis encrasicolus (L.), OCCURRING IN THE LAGOON OF LESINA (SOUTHWESTERN ADRIATIC SEA, ITALY)

Coastal lagoons are highly connected to the sea and many fish species enter into these environments remaining there for short periods. The European anchovy, Engraulis encrasicolus (L.), is a species intensely exploited by fishing in the Adriatic Sea, and it occurs in the Lagoon of Lesina only during the spring-summer months, when it finds in the lagoon suitable environmental conditions that could enhance the fitness of individuals. The purpose of this work was to characterize the European anchovy population in the Lagoon of Lesina, by studying the reproductive biology and estimating the age, size and growth parameters of the specimens. The study also aimed at identifying any relationship between the growth and maturity of anchovy and some environmental parameters. To achieve this goal, samples of European anchovy were collected about every fifteen days between May and September 2012, using fyke-nets. At the same time, water temperature, salinity, oxygen concentration and pH were measured with a multiparametric probe. In addition, water samples were collected for the chlorophyll a and suspended particulate matter measurements, and to describe phytoplankton assemblages of the lagoon. In the laboratory, each specimen was measured and weighted; the otoliths were removed and stored dry in labelled envelopes for age determination. The sex was determined and the fish gonads were macroscopically classified. Moreover, gonad samples (at least 10 specimens for each sampling) were fixed in 4% buffered formalin for histological analysis. Water samples for photosynthetic pigments were sequentially filtered to separate three size classes: total, micro- and nano-phytoplankton for spectrofluorometric measurements. Water samples for total suspended solids were filtered and dried to estimate their concentrations. The phytoplankton cells were counted and identified by inverted microscope and the organisms were classified and grouped into three main taxonomic components: diatoms, dinoflagellates and others. The most significant results are illustrated.