Poissons des côtes nord-ouest africaines (Campagnes de la « Thalassa » 1962 et 1968)

From the second half of the 19th century, several oceanographic ships prospected the northwest coasts of Africa, but they only did so in passing. Their main zone of research was more extensive or farther from European coasts. Under these conditions, the area of knowledge remained limited for a long time, in this region, to shallow waters. Even just ten years or so ago, documents dealing with the ecology and nature of the sea beds more than 200 metres down were rare, in spite of the exploitation of which these sea beds were the target after the end of the First World War. It was to fill this gap, at least partially, that during the year 1962, from 6 November to 12 December, the Institute of Fishing's research ship, the Thalassa, conducted a mission for prospecting and studying trawlable sea beds all along the coasts of the Rio de Oro and Mauritania; 62 fishing operations were performed on that occasion. However, given the immense fishing effort deployed since this campaign by the ships of a large number of countries, it became necessary to observe the changes in yield and to supplement the data already obtained by using new research. That is why the Thalassa conducted 40 new trawls from 29 March to 18 April 1968. This time, the zone of operation extended from Cape Juby to the Fosse de Cayar Submarine Canyon, near Cape Verde, to Senegal. The distribution of the trawls conducted during these two missions is indicated in Figure 1. Out of a total of 102 catches, 58 are located on the continental shelf and its edge between 12 and 200 metres, 44 on the bank from approximately 200 to 800 metres. These two missions have already been the subject of publications from the Institute of Fishing; they concern the ecology and even the biology or taxonomy of certain species. At all events, the significant amount of knowledge and observations about fish acquired on these occasions merited being assembled into a single work; this is what we tried to do here. It was unfortunately not physically possible to publish this work in one go. The pages that follow are an early part dedicated to Selacians and Chimeras. The other parts will appear in future instalments of this Journal. ...