Ascent of elvers, anguilla anguilla (L.), and prospects for their use in aquaculture

Abstract

An overall picture of the European elver’s behaviour during coastward migration and entrance into inland waters emerges from a survey of the literature. The factors influencing trophic migration are discussed. In particular, the data relevant to the Mediterranean area are taken into account. The observations by the authors over the course of one, year at the outlet of the River Arno confirm that the behaviour of elvers there is similar to that described for the North Atlantic coast. The ascent of the elvers at the sampling point (located approximately 1100 m upstream from the outlet) is greater in the hours immediately following sunset. A clear-cut influence upon the amount of the ascent is due to tidal movements, and catches are larger after the peaks registered with flood tide. Temperature of the waters appears to have some effect, but no fluctuations in the ascent are attributable to the flow of the river and to the phases of the moon. The increase in the demand for elvers to replace stocks and for intensive culture is the basis for discussion and analysis of the principal objectives for action aimed at the rational utili: zation of this natural resource. © 1980 Taylor & Francis Group, LLC.