Fish Population and Behavior Revealed by Instantaneous Continental Shelf-Scale Imaging

Abstract

Until now, continental shelf environments have been monitored with highly localized line-transect methods from slow-moving research vessels. These methods significantly undersample fish populations in time and space, leaving an incomplete and ambiguous record of abundance and behavior. We show that fish populations in continental shelf environments can be instantaneously imaged over thousands of square kilometers and continuously monitored by a remote sensing technique in which the ocean acts as an acoustic waveguide. The technique has revealed the instantaneous horizontal structural characteristics and volatile short-term behavior of very large fish shoals, containing tens of millions of fish and stretching for many kilometers.

Gaussian theory for spatially distributed self-propelled particles

“…Starting then with this homogeneous field, the instability disappeared. After integrating 128 units of time, we put K back to 1/8, and integrated for 2 16 units of time in order that the system can relax with the correct K-value. During the last 2 11 units of time of the relaxation we sampled the system and computed the wanted value of the global polarization.…”

“…There are many examples, such as birds flocks [11][12][13][14][15], schools of fishes [16][17][18], herds of animals [19,20], bacteria colonies [21][22][23], clusters of cells [24], and vibrated granular particles [25,26]. One of the fundamental and pioneer works in active matter is the introduction of a dynamical microscopic model, known as Vicsek model, to study the emergence of collective behavior [27].…”

A collective navigation hypothesis for homeward migration in anadromous salmonids

“…4, catch size is a direct measure of local density of fish, where the spatial scale is a function of the area sampled by the purse seine net. We use catch size as a proxy for group size, but note that this may under sample larger groups if they exceed the size of the net (Makris et al 2006) or if larger groups more easily evade capture. With this in mind, we note that the catch size distribution we observed for salmon is consistent with the broad distributions of group sizes predicted for (Gueron and Levin 1995;Gueron 1998;Niwa 2004;Ma et al 2011), and observed in, fission fusion populations, including those of fish (Bona beau et al 1999a;Makris et al 2006).…”

Acoustic-waveguide sonar finds enormous fish shoals

“…The recently published account of the experiment details the structure and dynamics of perhaps the largest massing of animals imaged in nature. 3 …”