Because of its responsiveness to changes in the marine environment, it has been suggested by Rose in 2005 that the capelin, a small pelagic fish that is key to the ecology and fisheries of the North Atlantic, could be seen as a “canary in the coalmine” to detect signals of changes in the Arctic Ocean. We will describe the historical data that make possible a quantitative assessment of the geographical shift capelin migration-paths and spawning grounds undergo with increasing temperature, and the time it takes to make these shifts long-lasting. Then we introduce recent data that make these quantitativemeasurements more accurate and predictive. The Copernicus database of the European Union is used to examine the evolution of the returning Atlantic water (from Svalbard) that is forming a warmer and saltier boundary current under the colder and fresher East Greenland polar current. The returning Atlantic water has a temperature range (1 to 4 degrees Centigrade) suitable for feeding migrations of the capelin. This current is reaching further north along the coast of North East Greenland and we use Copernicus to simulate this evolution. We then validate the Copernicus data with measurements made in the fall expeditions of the Marine and Freshwater Research Institute, in Iceland, along the East Coast of Greenland. We identify trends in Copernicus data showing that the returning Atlantic water boundary current may reach the major glacier streams draining a large portion of the Greenland Glacier, in the relatively near future, and use the capelin data to predict when this may happen.@en

In this paper, we study simulations of the schooling and swarming behavior of a mathematical model for the motion of pelagic fish. We use a derivative of a discrete model of interacting particles originated by Vicsek and Czirók et al. [A. Czirók, T. Vicsek, Collective behavior of interacting self-propelled particles, Physica A 281 (2000) 17-29; A. Czirók, H. Stanley, T. Vicsek, Spontaneously ordered motion of self-propelled particles, Journal of Physics A: Mathematical General 30 (1997) 1375-1385; T. Vicsek, A. Czirók, E. Ben-Jacob, I. Cohen, O. Shochet, Novel type of phase transition in a system of self-driven particles, Physical Review Letters 75 (6) (1995) 1226-1229; T. Vicsek, A. Czirók, I. Farkas, D. Helbing, Application of statistical mechanics to collective motion in biology, Physica A 274 (1999) 182-189]. Recently, a system of ODEs was derived from this model [B. Birnir, An ODE model of the motion of pelagic fish, Journal of Statistical Physics 128 (1/2) (2007) 535-568], and using these ODEs, we find transitory and long-term behavior of the discrete system. In particular, we numerically find stationary, migratory, and circling behavior in both the discrete and the ODE model and two types of swarming behavior in the discrete model. The migratory solutions are numerically stable and the circling solutions are metastable. We find a stable circulating ring solution of the discrete system where the fish travel in opposite directions within an annulus. We also find the origin of noise-driven swarming when repulsion and attraction are absent and the fish interact solely via orientation.@en