Migration and aggregation behavior of Euphausia superba

Meng Zhou, University of Massachusetts Boston

Yiwu Zhu, University of Massachusetts Boston

Ryan D. Dorland, University of Massachusetts Boston

Migration and aggregation behavior of Euphausia superba is critical in determining the fate of natural populations in a dynamic physical and biological environment. Observations using traditional net methods and advanced acoustic methods have provided us general patterns of migration and aggregations of Euphausia superba associated with light, predators, and topographic features. Most of mathematical theories on aggregation are based on random walking and autocoherence between animals. However observations based on dynamic theories are rare because there is a lack of methods to follow a Euphausia superba swarm examining the temporal variation of migration patterns, patch sizes, swimming velocities and aggregation behavior.

Migration and aggregation behavior of Euphausia superba were studied in Marguerite Bay and its vicinity, Antarctic Peninsula using a vessel mounted (VM) Acoustic Doppler Current Profiler (ADCP), and a Multiple Opening and Closing Nets and Environmental Sampling System (MOCNESS), during the US Southern Ocean GLOBEC project cruises. We examine the temporal variation in aggregation patterns of Euphausia superba associated with diel migration, and spatial variation associated with ice coverage and presence of predators. We also investigate their swimming behavior within Euphausia superba aggregations by applying the acoustic Doppler technology. Results lead to some new considerations of aggregation theories.