Population size structure, growth and reproduction of the European anchovy (Engraulis encrasicolus, L.) in the Lagoon of Lesina (south-western Adriatic Sea, Italy)
Abstract
1 - The purpose of this study was to describe the basic characteristics of the European anchovy occurring in the Lagoon of Lesina in order to increase our knowledge of the ecology of the species in a lagoon ecosystem.
2 - Samples were collected between May and November 2012 using fyke nets. A hundred individuals per sample were measured and weighed. Sex was determined and the fish gonads were macroscopically classified. Length-frequency histograms were obtained, and the length-weight relationships and condition factors were estimated.
3 - The results of this study showed that the anchovies caught in the Lagoon of Lesina were relatively small. The growth of anchovies in the lagoon was often positively allometric (b>3) and exponent b was frequently greater than the value estimated for specimens in the Adriatic Sea in the same months.
4 - The sex ratio of anchovies in this study was skewed towards females in almost all the sampling period. Macroscopic analysis of the gonads revealed that spawning took place during spring-summer, and it prolonged until October in the females. One peak of ripe females and males was observed in June and one in August-September.
5 - This study suggests that the anchovy population in the Lagoon of Lesina is probably composed of a large number of young individuals at the first maturity. Individual growth seems to be positively affected by the environmental conditions of the lagoon, which probably provide the anchovies with a substantial trophic advantage.
2 - Samples were collected between May and November 2012 using fyke nets. A hundred individuals per sample were measured and weighed. Sex was determined and the fish gonads were macroscopically classified. Length-frequency histograms were obtained, and the length-weight relationships and condition factors were estimated.
3 - The results of this study showed that the anchovies caught in the Lagoon of Lesina were relatively small. The growth of anchovies in the lagoon was often positively allometric (b>3) and exponent b was frequently greater than the value estimated for specimens in the Adriatic Sea in the same months.
4 - The sex ratio of anchovies in this study was skewed towards females in almost all the sampling period. Macroscopic analysis of the gonads revealed that spawning took place during spring-summer, and it prolonged until October in the females. One peak of ripe females and males was observed in June and one in August-September.
5 - This study suggests that the anchovy population in the Lagoon of Lesina is probably composed of a large number of young individuals at the first maturity. Individual growth seems to be positively affected by the environmental conditions of the lagoon, which probably provide the anchovies with a substantial trophic advantage.
DOI Code:
10.1285/i1825229Xv7n2p41
Keywords:
Engraulis encrasicolus; population structure; length-weight relationship; condition factor; spawning period; coastal lagoon; Adriatic Sea
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