Surface swarms of the lanternfish Myctophum punctatum associated to dolphin presence

Abstract

The neustonic layer of the ocean are visited at night time by a large number of organisms for feeding or breeding. This study reports large aggregations of the myctophid Myctophum punctatum at night in the strictly sea surface layer of the water column and the co-occurrence of dolphins swimming and probably feeding on these fish. The study was based on fish captures obtained from neuston hauls and dolphins observations in the Alboran Sea (western Mediterranean), and in oceanic waters off Lisboa (temperate Atlantic). Data on the abundance, biomass, size frequency distributions and Gonadosomatic Index of M. punctatum were analysed, and the relevance of these high aggregations both for the biology of the species and as a source of prey for the co-occurring dolphins is discussed.