From Individuals to Local Population Densities: Movements of North Atlantic Bluefin Tuna (Thunnus Thynnus) in the Gulf of Maine/Northwestern Atlantic

Abstract

North Atlantic bluefin tuna have high rates of spatial redistribution and display complex aggregation behavior in response to changes in their environment. This paper presents preliminary results obtained from an analysis of individual movements of giant bluefin tuna derived from tracking studies conducted in association with aerial surveys in the Gulf of Maine (NW Atlantic). From the perspective of a correlated and biased random walk movement model, we examined how alternative behavioral modes of tuna movement affect estimation of local population density. We summarize information needed to link movements and behavior of individuals and schools (i.e., depth and surfacing behaviour, spatial mixing, residency, and school and size distribution) in order to portray spatial and temporal dynamics of the bluefin assemblage. Our goals are to integrate hydroacoustic tracking and aerial survey movement data in order formulate a modeling and simulation framework that will generate predictions and estimates of local population densities. This will support the development of fishery-independent assessments of adult bluefin tuna that are crucial to accurate monitoring, management, and rebuilding of the Atlantic population.