Quantification of Wide-Area Norwegian Spring-Spawning Herring Population Density with Ocean Acoustic Waveguide Remote Sensing (OAWRS)

Abstract

Norwegian spring-spawning herring are a critical economic resource for multiple nations in the North Atlantic and a keystone species of the Nordic Seas ecosystem. Given the wide areas that the herring occupy, it is difficult to accurately measure the population size and spatial distribution. Ocean Acoustic Waveguide Remote Sensing (OAWRS) was used to instantaneously measure the areal population density of Norwegian herring over more than one thousand square kilometers in spawning grounds near Ålesund, Norway. In the vicinity of the Ålesund trench near peak spawning, significant attenuation in signal-to-noise ratio and mean sensing range was observed after nautical sunset that had not been observed in previous OAWRS surveys in the Nordic Seas or in other regions. We show that this range-dependent decay along a given propagation path was caused by attenuation through dense herring shoals forming at sunset and persisting through the evening for transmissions near the swimbladder resonance peak. OAWRS transmissions are corrected for attenuation in a manner consistent with waveguide scattering theory and simultaneous downward directed local line-transect measurements in the region in order to produce instantaneous wide-area population density maps. Corresponding measured reductions in the median sensing range over the azimuth before ambient noise limitation are shown to be theoretically predictable from waveguide scattering theory and observed population densities. Spatial-temporal inhomogeneities in wide-area herring distributions seen synoptically in OAWRS imagery show that standard sparsely spaced line-transect surveys through this region during spawning can lead to large errors in the estimated population due to spatial and temporal undersampling.

Optimal Automatic Wide-Area Discrimination of Fish Shoals from Seafloor Geology with Multi-Spectral Ocean Acoustic Waveguide Remote Sensing in the Gulf of Maine

“…The data presented here are from the Gulf of Maine 2006 OAWRS Experiment (Figure 1) conducted on the western flank of Georges Bank area from 19 September to 6 October 2006, in conjunction with the U.S. National Marine Fisheries Service Annual Atlantic Herring Acoustic Survey [4,5,14]. In this experiment, spatial and temporal population density distributions, group behavior and physical scattering characteristics of Atlantic Herring (Clupea harengus) were quantified during their annual spawning period in their primary spawning ground in the Gulf of Maine [6][7][8]10,12,13,[16][17][18][19]28].…”

“…The OAWRS technology has been shown to enable instantaneous population density quantification and continuous monitoring of fish populations over thousands of square kilometers, with space-time sampling rates tens of thousands to millions of times higher than line transect methods by employing the natural capacity of the oceans for long-range sound channeling at lower frequencies [3,4,6]. Fish populations and behavior have been studied with OAWRS over wide areas in the Mid-Atlantic Bite [3], the Gulf of Maine [7] and the Nordic Seas [8][9][10][11]. To summarize some key results, the instantaneous horizontal structures and volatile short-term behavior of very large fish shoals, containing tens to hundreds of millions of fish and stretching for many kilometers, have been revealed by OAWRS, including the presence of population density waves within the shoals that exceed fish swimming speeds [3,7].…”

“…Cod spawning shoals sizes quantified with OAWRS in Lofoten Norway, with spatial diameters of up to roughly 40 km, were used to help quantify conditions leading to Cod stock collapses [8]. These results have been obtained in tandem with advances in accurately predicting and modeling the acoustic scattering from marine life that makes OAWRS possible [6,7,[10][11][12][15][16][17][18][19][20] as well as with advances in equipment development for long-range, wide-area ocean acoustics sensing [21][22][23].…”

Research on the spatiotemporal distribution and evolution of remote sensing: A data-driven analysis

“…caused by population growth or develop new technologies for energy surveys (for mineral exploration, etc.) to reduce costs and improve the efficiency of energy exploration (Duane et al, 2021;Chen et al, 2022;Wu et al, 2022). Gonzalez and Gonzalez, 2016;Hu et al, 2019), which means that it takes time from publication to citation (Campanario, 2011;Chi, 2016).…”

High-Order Domain Feature Extraction Technology for Ocean Acoustic Observation Signals: A Review

“…At the same time, low visibility of underwater observation makes underwater signal sensing mainly rely on hydrophones, and acoustic waves have become the main medium of underwater observation. Although lots of studies have shown the great potential of acoustic waves for underwater observation, they are limited by complex underwater environments, and obtained detection results include target signals and substantial background noises [3], [4]. At the same time, generally acquired oceanic acoustic observation signals are nonstationary nonlinear signals, and the conventional frequency domain analysis method and second-order domain method cannot accurately distinguish the target signal from background noise.…”