L'ichthyoplancton pour l'évaluation des stocks de thons en Méditerranée

We present in this document the results of a ichthyoplankton survey made in July 1977, in the western mediterranean, on the R.V. Cornide de Saavedra. This document deals mainly with the distribution and abundance of bluefin tuna larvae (Thunnus thynnus L.), albacore (Thunnus alalunga Bonn.) and frigate mackerel (Auxis thazard Lac.). In total 104 bluefin, 105 albacore and 220 frigate mackerel larvae were caught. On the basis of their abundance, and following SETTE and AHLSTROM (1948) method, an estimate of the size of the spawning stock for bluefin tuna is presented in table 3. The expression P = n . t./e . f., give us the famel population where ni is the total number of larvae estimated in the total area, t is the spawning period in days, e is the estimated age of the average larvae captured and f is the fecundity in eggs per gram of body weight.