Nahrungsbiologie dreier Myctophidenarten, Benthosema glaciale (Reinhardt, 1837), Ceratoscopelus maderensis (Lowe, 1839) und Myctophum (M.) punctatum Rafinesque, 1810, des nordwestafrikanischen Auftriebsgebietes

Analyses were made of the stomach contens of three Myctophid species (B. glaciale) C. maderensis) and M. punctatum) collected on the shelf off Cap Blanc during the first leg of the "Auftrieb 72" Expedition. The material was sampled using a neuston net, for surface samples, a "Langhai" (modified Gulf Sampler) and a ring trawl for hauls down to 174 and 150 m respectively. All nets had a uniform mesh size of 500 μm. All three species did not usually occur on the shelf area; the 200 m depth line appeared to be a clear distribution barrier. The stomach contents were analyzed numerically and the results expressed in terms of composition and occurrence of food. B. glaciale were only caught at night and were generally not found in the surface layers. Hauls made during the day, including those using the deeper fishing gear, were negative. The length-frequency distribution maximum was at 30 mm, the longest fish measured 53 mm. 60% of the stomachs were empty. Calanoid copepods dominate the food spectrum. Smaller B. glaciale feed on copepodites. C. maderensis were only caught at night and mainly near the surface. Day hauls were negative for all gear. The fish ranged in length from 20 to 68 mm, the smaller individuals being caught by the deeper sampling gear. The higher percentage of full stomachs in the neuston catches indicates considerable nocturnal feeding activity in the upper water layers. Copepods, particularly Calanus sp., were the main food items, however adult and larval forms of other planktonic crustacea were also ingested. M. punctatum were caught only at night and almost exclusively by the neuston net. With a length range of 16 to 80 mm, the length-frequency maximum was at 67 mm. Only a few stomachs were either empty or only slightly filled. Important food organisms were Copepods (Calanits) juvenile Pleuromamma), Euphausiids, zoea stages of Brachyura and fish fry, e. g. Sardina pilchardus