MIGRATHON - AN EXPERT-SYSTEM TO ESTIMATE THE FISH MIGRATORY FLOWS BETWEEN DIFFERENT AREAS - APPLICATION TO THE SKIPJACK TUNA (KATSUWONUS-PELAMIS) IN EASTERN TROPICAL ATLANTIC

We have created a simple expert system to estimate migratory rates bet ween fishing areas. This expert system is only based on fishery data. Quarterly migratory flows are calculated, using a comparison between t wo different estimations of number of fish, per area and per age, the first one including migration and the second not. To obtain the first estimation, we use number of fish by age, resulting from a cohort anal ysis, which are distributed by areas. The second estimation is calcula ted by the model, period by period, from the preceding estimation of n umber of fishes in each zone and for each age. The expert system is ap plied to the Atlantic skipjack tuna. Migration flows are analyzed by g roup of ages, and all ages together. The model presents many restricti ons, nevertheless results seem to be in accordance with present knowle dge on skipjack migration in the Atlantic Ocean.