Deep scattering layer - From siphonophores to deep scattering layers: uncertainty ranges for the estimation of global mesopelagic fish biomass. ICES J. Mar. Sci. 76 , 718-733 (2019). Article Google Scholar

 
Scattering layers have been dealt with by many authors in various areas. Most of the studies are on zooplankton distribution and vertical movements and/or technical aspects (Magnœsson, 1996). The deep scattering layer in the Irminger Sea was studied by Magnœsson (1996), using information obtained. Fox news lexington ky

In the mesopelagic zone, two separate deep scattering layers (DSLs) were evident: one dense layer was most prominent in the 18 kHz echodata between 450 and 600 m (Figs. 3, 4 and 5b) and between 400 and 700 m in the 38 kHz data (upper mesopelagic scattering layer, hereafter referred to as principal DSL and layer 2).In the present study, patterns of deep scattering layers (DSLs) were characterized using relative acoustic backscatter from a ship-mounted 38-kHz phased-array, acoustic Doppler current profiler (ADCP) in the northern Gulf of Mexico in summers 2002 and 2003. Temporal patterns of scattering layers were analyzed with respect to the timing of the ...Jan 11, 2021 · scattering layers and/or ’deep scattering layers’ (DSLs) in the mesopelagic region, which can be. seen rising around dusk and descending around dawn (Hays, 2003). Sound scattering layers are. Abstract. Bathyscaphe dives in the San Diego Trough have revealed a close spatial relation between siphonophores and the deep scattering layer as recorded by precision depth recording echo-sounders. Measurements of gas bubbles within the flotation structures of Nanomia bijuga captured in a closing net in an ascended scattering layer indicate ...Migrant deep scattering layers and non-migrant layers, stronger at 18 and 38 kHz respectively, are two separate entities with distinct spatial and seasonal dynamics. Migrant layers vary in number ...The term false bottom can also refer to the deep scattering layer in the ocean, a phenomenon where a layer of marine organisms deep in the ocean can be mistaken by sonar for the seabed. In Polar research, the false bottom refers to the type of thin sea ice which is formed underwater at the interface of low-salinity meltwater and saline seawater ...Two small shallow scattering layers (SSLs) between 0 and 100 m, and one large deep scattering layer (DSL) at around 550 m depth, characterized the mean vertical distribution of MTLOs. A machine-learning model (eXtreme Gradient tree Boosting algorithm, XGBoost) was fitted to explain the acoustic profile clusters with environmental …Image courtesy of Exploring Migrating Deep-Sea Scattering Layers. Download largest version (jpg, 47 KB). The ship was instrumented with a multifrequency …The deep scattering layer (DSL) is a ubiquitous acoustic signature found across all oceans and arguably the dominant feature structuring the pelagic open ocean ecosystem. It is formed by mesopelagic fishes and pelagic invertebrates. The DSL animals are an important food source for marine megafauna and contribute to the biological carbon pump through …However, very little is known about the existence of harvestable fish stocks in this 3.3 million-square kilometer ecosystem around the North Pole. Crossing the Eurasian Basin, we documented an uninterrupted 3170-kilometer-long deep scattering layer (DSL) with zooplankton and small fish in the Atlantic water layer at 100- to 500-meter depth.Whether you’re addicted to fried comfort food or you just enjoy the occasional fried dish, you’re always prepared when you have your own deep fryer in your kitchen. The best deep fryers come in many sizes to suit every home cook in every we...To test this hypothesis we investigated, for the first time, the lability of dissolved organic matter and the carbon flow through heterotrophic prokaryotes within the acoustic deep scattering layer (DSL) of the mesopelagic Red Sea during daytime (550 m depth, Figure 1), and compare it with two overlaying water layers; the surface (5 m) and …The deep scattering layer thickness is up to hundreds of meters, and the scatterer has obvious biological behaviour, namely deep during the daytime, and shallow at night. In addition, seabed ...However, very little is known about the existence of harvestable fish stocks in this 3.3 million-square kilometer ecosystem around the North Pole. Crossing the Eurasian Basin, we documented an uninterrupted 3170-kilometer-long deep scattering layer (DSL) with zooplankton and small fish in the Atlantic water layer at 100- to 500-meter depth.The 7 layer salad is a classic dish that has been around for decades. This salad is easy to make and can be served as a side dish or main course. It’s also a great way to use up any leftover vegetables in your fridge.... scattering structures. The deep scattering layer biological constituents were determined from vertical and oblique hauls with zooplankton nets and pelagic ...The deep scattering layer (DSL) in the Gulf of Mexico has been studied, over a period of three years, utilizing a precision depth recorder operating at 12 kHz. The DSL appears to be divided into four main daytime layers. The west-central Gulf shows little deep layering. No definite correlation of DSL and physical parameters was arrived at.Small fish occur at very low abundances in the 200-600 m deep Atlantic water layer of the Amundsen Basin as shown by the unique hydroacoustic dataset collected by the EFICA Consortium that showed ...deep scattering layer located just above the core of the vent plume. The positive acoustic anomaly was bimodal in shape, with a vertical separation of about 50 m be- tween peaks. Within the core ...Two small shallow scattering layers (SSLs) between 0 and 100 m, and one large deep scattering layer (DSL) at around 550 m depth, characterized the mean vertical distribution of MTLOs.During Operation HIGHJUMP (U. S. Navy Antarctic Development Project, 1947), the writer frequently noted the presence of a layer of deep scatterers on the fathogram of the USS HENDERSON. This layer partially scatters the outgoing sound signal of the recording echo sounder during daylight hours so that a reflection is recorded which has the appearance of a false bottom at various depths between ...Dec 11, 2021 · The Scripps Institution of Oceanography scientist Martin Johnson proposed an explanation: The deep scattering layer could be marine animals migrating up to the surface. In June of 1945, he tested ... Bathyscaphe dives in the San Diego Trough have revealed a close spatial relation between siphonophores and the deep scattering layer as recorded by precision depth recording echo-sounders. Measurements of gas bubbles within the flotation structures of Nanomia bijuga captured in a closing net in an ascended scattering layer indicate that these are very close to the resonant size for 12-kcy/sec ...Light scattering is considered a fundamental limitation for deep imaging 1,2,3,4 and focusing 5,6,7,8.There are two reasons, the inhomogeneity of biological tissue and the collision between ...The scattering layer also acts as a marker for the thermocline, making possible some continuous measurements of thermoeline depth. INTRODUCTION Trm~ have been many accounts of deep scattering layers detected by echo-sounding, but rather fewer reports of shallow layers or layers connected with density changes.The acoustic snapshots revealing spatio-temporal sound scattering patterns, deep scattering layer, and diel vertical migration (Fig. 2) can offer improved ecological insights 34,35 for marine ...the deep scattering layer, and the whole set of these sheets as the model of the DSL vertical structure. The sheets were numbered. For every i th sheet, we calcu-lated the depths of its upper and lower boundaries, the backscattering coefficient m determined as the mean value of the backscattering coefficient between theSLs were permanent features with two main layers, shallow scattering layers (SSLs) and deep scattering layers (DSLs). Over seamount plateaus, SSLs aggregated close to the seafloor during the day and in slightly shallower waters at night. Backscatter intensity on plateaus varied little between day and night and was consistently higher than in ...Welcome to CMFRI Repository - CMFRI RepositoryFeb 7, 2022 · Hydroacoustic data used for identifying deep scattering layers (DSL) and DVM patterns were recorded in March/April 2016 on an east–west transect at circa 58° N in the Rockall Trough during the ... extensive areas, of the deep scattering layer in the Pacific and Antarctic oceans, and on this ground alone, the presence of scattering in New Zealand waters could be expected. Recent investigations of occurrences and dis­ tribution of plankton in New Zealand waters (Bary, in press) suggest an abundant zoo­ plankton, and it would appear also thatThese deep scattering layers have been studied since the 1940s 4,5 and the associated methods have been reviewed in various publications. 6,7 Despite its importance, much remains to be learned about the mesopelagic zone. Shipboard echosounders are commonly used to survey the mesopelagic zone. The frequencies of …A substantial amount of mesopelagic biomass in the 1 mm+ size fraction is contained, during the day, within deep scattering layers (DSLs), primarily made up of fish, zooplankton, squid, and jellyfish. DSLs are detected using echosounders, which emit sound waves and record backscatter (see Chu, 2011, for a review).The northern and central regimes were structurally similar, both exhibiting a pronounced shallow and deep scattering layer, although the vertical positions of these layers are shifted upwards by 50-100 m in the SCZ. The scattering layer structure in the area south of 42°S was quite different, with backscatter being distributed more uniformly ...Migrant deep scattering layers and non-migrant layers, stronger at 18 and 38 kHz respectively, are two separate entities with distinct spatial and seasonal dynamics. Migrant layers vary in number and intensity with primary production while the main non-migrant layer (400–800 m depth) is constant in intensity throughout the year.May 28, 2021 · For example, spotted dolphins increase activity and deep dives at sunset to coincide with the movement of the deep scattering layer to surface waters (Scott and Chivers, 2009). Increased incidence of fast start events at sunrise and sunset may be linked to this period having the highest predicted feeding rates (Thygesen and Patterson, 2019). The daytime depth of the deep scattering layers in major biotic regions of the Pacific Ocean are analyzed and found to be correlated with light levels, although at some locations a sharp ...The deep scattering layer is made up of lots of marine animals like fish, squid, and jellyfish, to name a few, many of which are bioluminescent. They can be found throughout the oceans but are ...(DSL)Sound-reflecting layer in ocean waters, consisting of a stratified, dense concentration of zooplankton and fish. Such organism-rich layers, which cause scattering of sound as recorded on an echo sounder, may be 50-200m thick.Humans are mostly unaware of this daily aquatic movement, known as diel vertical migration, but it's the largest routine migration of life on Earth. Current estimates indicate some 10 billion tons ...This study aimed to add light-avoidance as a categorizing technique for the study of mesopelagic acoustic layers. Data recorded along the 20° W parallel from 20° N to Iceland showed three types of mesopelagic layers: the non-avoiding non-migrant deep scattering layer (NMDSL), which dropped its intensity toward the north, the avoiding migrating fish layers (MDSL), which were more intense at ...The deep scattering layer (DSL), located between 400 and 600 m at our study site (Klevjer et al., 2016), is dominated by Benthosema pterotum lanternfishes.The phenomenon of the false sea floor became known as the deep scattering layer or DSL, because it scatters the sonar signal. Fish adaptations to the zones Typically, species such as lanternfish (Myctophids) and bristlemouths (Gonostomatids), which make vertical migrations each day, possess a swim bladder. Underwater sound speed as a function of depth. Data derived from readings taken north of Hawaii in the Pacific Ocean and sourced from the World Ocean Atlas, 2005 edition.Note the SOFAR channel axis at ca. 750 m depth, where sound speed is shown at its lowest.. The SOFAR channel (short for sound fixing and ranging channel), or deep sound channel (DSC), is a horizontal layer of water in the ...Scattering layer definition, undefined See more. Games; Featured; Pop culture; Writing tips; Games. Daily Crossword; Word Puzzle; Word Finder; All games; ... typically move upward at night to feed on phytoplankton and downward during the day, as deep as 1,000 m (3,280 ft), probably to escape predators. Also called deep scattering layer. Words ...Human skin has three layers: epidermis, dermis and hypodermis. Each layer has a unique role in protecting the body and maintaining the functions that are more than skin deep. Of the three layers, only the epidermis is typically ever seen.Deep scattering layer definition, a zone of biological origin within the ocean, at a depth of 900–1200 feet (270–360 meters), which scatters sounding echoes. See more.With the help of extra inserted scattering layers and a deep learning algorithm, the target hidden from view can be stably recovered while the directly uncovered view is reduced to 0.097% of the whole field of view, successfully removing the influence of large foreground occlusions. This scattering-assisted computational imaging has wide ...The deep scattering layer (DSL) is a ubiquitous feature of the global ocean. It consists of a large community of mesopelagic organisms which links the marine food web and has recently garnered ...Deep scattering layers (DSLs) are ubiquitous features of the global ocean that comprise biomass-rich communities of zooplankton and fish. They are so dense (biomass per unit volume) that in early acoustic surveys echoes from DSLs were mistaken for seabed echoes, hence the common name "false bottom."Deep-Sea Research, 1969, Vol. 16, pp. 117 to 125. Pergamon Press. Printed in Great Britain. On the quantitative distribution of zooplankton in deep scattering layers* JOHANNES KINZER~" (Received 25 September 1968) Abstract--The plankton samples described have been collected in oblique hauls with closing nets from the depth of the deep scattering layer (DSL), as recorded by art ELAC echo ...13 thg 6, 2012 ... Almost all organisms in the deep layers migrated to the near-surface waters during the night. Backscatter from a 300 kHz lowered Acoustic ...A representative echogram illustrating the scattering coefficient at 38 kHz along CalCOFI line 76.7. The transect was conducted from nearshore (east) to offshore (west), from 10:00 PDT on 15 May to 12:30 PDT on 16 May, 2010. The pink and green points indicate the upper and lower boundaries of the deep scattering layer (DSL), respectively.1. Introduction. Deep Scattering Layers (DSLs) were first noted in records of high frequency sonars during WWII, as a layer of enhanced acoustical backscatter, and since those early observations DSLs have been found throughout deep sea regions of the world ocean (Irigoien et al., 2014).Initial observations revealed that the depths and …deep scattering layer (DSL; usually 400-600 m deep) and the depths to which whales dived. The results of the study investigate differences in DSL characteristics between divergent zones and non-divergent zones, and examine connections relating to variations in sperm whale dive patterns. The analysis of 38 kHz ADCP data showed that there weredeep-sea. Keywords: bioluminescence, deep scattering layer, diel vertical migrations, activity rhythms, monitoring technologies, neutrino telescopes INTRODUCTION The deep sea (i.e., >200 m depth) is the largest biome of the planet. It represents the 65% of the whole planet's surface and contains more than 95% of the biosphere, with more than ...Large-scale geographic variations in daytime mesopelagic scattering layer depths have been known for a long time and have previously been ascribed to latitude 27 or variations in light levels 28,29.Distinct deep sound scattering layers are prevalent throughout the ocean mesopelagic zones (200-1000 m depths). These deep sound scattering layers are often characterized by daily vertical migration, in which many of the inhabitants of the ocean mesopelagic communities migrate to shallow waters during the night to feed, and descend during the day to avoid predators.Question: (5 pts) The 'Deep Scattering Layer' refers to the aggregation of animals in the upper mesopelagic zone that reflect sound. (A) (2.5 pts) Why do many animals in this layer move to the surface at night ? (B) (2.5 pts) And why do they return to deep water during the daytime ?Define deep scattering layer. deep scattering layer synonyms, deep scattering layer pronunciation, deep scattering layer translation, English dictionary definition of deep scattering layer. n. See scattering layer.Deep scattering layers (DSLs) play an important role in pelagic food webs, serving as a vehicle for transferring energy between productive surface waters and the deep sea. We ex - plored the ...Introduction. Sound Scattering Layers (SSLs) are routinely observed with active acoustic devices in a great variety of ecosystems and over wide depth ranges in the global ocean [1-4].Deep Scattering Layers [] inhabiting the mesopelagic zone worldwide, are e.g. known to perform daily the largest migrations on earth [] and their fish component might dominate the world total fishes biomass [4, 7].Deep scattering layers (DSLs) are ubiquitous features of the global ocean that comprise biomass-rich communities of zooplankton and fish. They are so dense (biomass per unit volume) that in early acoustic surveys echoes from DSLs were mistaken for seabed echoes, hence the common name “false bottom.”In the shipboard data, a dominant scattering layer is seen between approximately 400 and 500 m depth, and a second, less intense scattering layer is observed between approximately 600 and 700 m depth. FIG. 2. View large Download slide ... Deep-scattering layer, gas-bladder density, and size estimates using a two …Netburn, A. N. & Anthony, K. Dissolved oxygen as a constraint on daytime deep scattering layer depth in the southern California current ecosystem. Deep. Res. Part I 104, 149-158 (2015).The deep scattering layer, sometimes referred to as the sound scattering layer, is a name given to a layer in the ocean consisting of a variety of marine animals. It was discovered through the use of sonar, as ships found a layer that scattered the sound and was thus sometimes mistaken for the seabed. For this reason it is sometimes called the ...The deep scattering layer is a stampede of sea monkeys whose combined biomass renders their nightly trek to feed on phytoplankton near the surface the largest animal migration on the planet ...Many of these species comprise the ubiquitous scattering layers (SLs) that undergo daily vertical migrations (DVM) of hundreds to thousands of meters, and link epipelagic with the meso- and bathypelagic biomes. ... The platforms will be targeting the daily movements of the SLs as they migrate between the deep waters (~1000 meter or …Sound scattering layers (SSLs) or deep scattering layers (DSLs) are vertically discrete (100s of m or less) water-column aggregations of organisms that can extend horizontally over 1000s of km (Kloser et al. 2009). The layers are comprised of pelagic organisms (organisms of the water column, as opposed to benthic organisms …Using optical reflection imaging, the most general case, as an instance, light reflected by the boundaries of the hidden objects behind an ideal single-scattering layer carries the shape ...visible in the ocean, the shallow and the deep scattering layer (SSL and DSL) occurring respectively in the epipelagic and the mesopelagic domains (0-200 and 200-1000 m depth), with the latter often por-tioned into multiple layers. Part of the biota forming the DSLs feed between dusk and dawn in the epipelagic zone, producing a thickerIf you work outdoors or in a cold environment, base layer clothing items can help keep you warm. take a look at our picks for the best base layer options below. If you buy something through our links, we may earn money from our affiliate pa...The deep-scattering layer (DSL) is a sound-reflecting layer that consists of: vertically migrating animals like lantern fishes. Light producing organs in deep sea animals are generally called: photophores. The relative amount of the Earth's water that is in the deep sea is about: three quarters/75%/3/4.The is the first report of scattering layers covering the whole distance of the deep parts of the Fram Strait, and strengthen the assumption about an east-west connection of organisms and young-of ...The Arabian Sea has number of phenomena that makes it interesting to explore by researchers. The monsoonal reversal system in the Arabian Sea not only changes the water circulation but also influences the biological productivity. The biologicalHydroacoustic data used for identifying deep scattering layers (DSL) and DVM patterns were recorded in March/April 2016 on an east-west transect at circa 58° N in the Rockall Trough during the ...This study aimed to add light-avoidance as a categorizing technique for the study of mesopelagic acoustic layers. Data recorded along the 20° W parallel from 20° N to Iceland showed three types of mesopelagic layers: the non-avoiding non-migrant deep scattering layer (NMDSL), which dropped its intensity toward the north, the avoiding migrating fish layers (MDSL), which were more intense at ...The phenomenon of the false sea floor became known as the deep scattering layer or DSL, because it scatters the sonar signal. Fish adaptations to the zones. Typically, species such as lanternfish (Myctophids) and bristlemouths (Gonostomatids), which make vertical migrations each day, possess a swim bladder. They also have well-developed muscles ...Transcribed Image Text: The deep scattering layer is created by which of these: a) seasonal changes in the thermocline O b) mesopelagic nekton O c) abyssopelagic plankton O d) phytoplankton blooms Expert Solution. Trending now This is a popular solution! Step by step Solved in 2 steps.The sound scattering layers, including the epipelagic surface scattering layer (SSL) and mesopelagic deep-sea scattering layer (DSL), were visually discernible on the slope area with bottom depths >300 m. S v echograms of the time-series stations are shown as an example of the diurnal vertical distribution of the acoustic backscatter (Fig. 3).Early studies of the deep scattering layer concluded that larger crustaceans and in particular euphausiids were significant in the deep scattering layer 50, but later studies showed that at the ...The deep scattering layers found near the hydrothermal plumes at Endeavour Ridge in summer are composed of a mixture of highly diverse upper ocean migratory zooplankton and non-migratory species more typical of the deep sea (Burd and Thomson 2015). Copepods consistently make up ~80% of the abundance and almost 50% of the total water column ...Even if distribution and migrations for deep scattering layers have been found to correlate with temperature or temperature differences on a global scale (Bianchi et al., 2013a; Klevjer et al., 2016), the relatively minor gradient across the 4 basins may not have a strong (i.e. detectable in our case) effect.Sound-scattering spectra of deep scattering layers in the western North Atlantic Ocean. J.B. Hersey, Richard H. Backus, Jessica Hellwig. Pages 196-200, IN3-IN4, 201-210 View PDF. Article preview. select article On the production of particulate organic carbon by heterotrophic processes in sea water.Echo signals were collected with a Simrad 200 kHz transducer across the shelf-break features off the northwest coast of Baja California (30°05'-30°42'N, 115°50'-116°26'W) during two diel cycles (July 1995) with the objective of describing vertical migrations of two dense deep scatter- ing layers (DSL) found near the shelf break. DSL records were made within an area -±50 m in the neritic ...Acoustic volume scattering measurements using 5 and 12 kHz pulses and explosive signals were made during the 1971 winter season at 18 deep‐water stations north and east of Auckland, New Zealand. Strong scattering layers (maximum volume scattering strengths −58 to −70 dB r e 1 yd) were observed at depths of about 500 yd during daytime ...A deep profiling (1000 m rated) stereo camera was operated in tandem with a split-beam five channel fisheries echosounder to record midwater scattering layers in detail across the oxygen minimum zone (OMZ) offshore of Baja California. A computer vision software library was developed to batch process the collected water column imagery and the ...

Deep scattering layer: Oceanographers and fishing crew are familiar with the "deep scattering layer" on fish-finder sonar systems. a) What is this layer? (Do not use the fanciful term "sea monkeys" in your answer.) b) Why does this layer move up and down? Expert Answer.. Kansas basketball dorms

deep scattering layer

Deep Scattering Layers. Marine mapping uses the echoes of acoustic signals to detect not only seabed topography, but also the presence of fish, crustaceans and other materials in mid-water [8]. In the ocean, these acoustic signals detect a ‘deep scattering layer’ (DSL) comprised of animals that migrate vertically in the water column.of deep CNNs come as an added disadvantage to automatic feature extraction ability [7]. To obtain an end-to-end framework, some SER studies use ... [15] use two-layer scattering coefficients with CNN layers to obtain a stable descriptor of speaker information from raw speech. In [16], authors compute different moments of ...The deep scattering layer is a stampede of sea monkeys whose combined biomass renders their nightly trek to feed on phytoplankton near the surface the largest animal migration on the planet ...The deep scattering layer (or DSL) is a region in the water column where there is a high density of marine organisms that reflect sound. During World War II, technicians using the then newly invented sonar system made a puzzling discovery: the seafloor seemed to be much shallower than expected, and its depth changed during the night!The largest and most researched is the primary deep scattering layer (DSL) prevalent throughout the world ocean at a mean depth of ∼500 m and covering a vertical extent of >200 m (16, 17). While the daytime occurrence of a single DSL is commonly observed, multiple scattering layers comprising different communities may be present …The phenomenon of the false sea floor became known as the deep scattering layer or DSL, because it scatters the sonar signal. Fish adaptations to the zones Typically, species such as lanternfish (Myctophids) and bristlemouths (Gonostomatids), which make vertical migrations each day, possess a swim bladder.The trend for the deep scattering layers (both at 18 and 38 kHz) is increasing depth from the beginning of the cruise until 30° N (Fig. 3e,f). At 38 kHz, the upper bound of the DSL deepened from ...deep scattering layer. Which of the following is/are correct? There may be more than one.-Tectonic motions and isostatic adjustment can change local sea level.-Winds and currents can create variations in local sea level changes. Which area is most likely to contain brackish water?30 thg 11, 2017 ... Some species in the deep scattering layer don't bother to migrate at all. Instead, they wait and eat other creatures returning with full ...Sonar data. The green layer in the water column is the deep scattering layer of diel vertically migrating mesopelagic zooplankton and fish. Illustration by Charles Frederick Holder of various bioluminescent fish that live in the mesopelagic zone. Although some light penetrates the mesopelagic zone, it is insufficient for photosynthesis.The largest and most researched is the primary deep scattering layer (DSL) prevalent throughout the world ocean at a mean depth of ∼500 m and covering a vertical extent of >200 m (16, 17). While the daytime occurrence of a single DSL is commonly observed, multiple scattering layers comprising different communi-The masses of life in what’s called the “deep scattering layer” (DSL) can be hundreds of feet thick and extend for hundreds of miles at various depths across the world’s oceans. In 2017, using a sonar-equipped underwater robot to probe the DSL off California, a team of researchers discovered that it contains distinct schools of animals ...Oct 4, 2023 · The largest and most researched is the primary deep scattering layer (DSL) prevalent throughout the world ocean at a mean depth of ∼500 m and covering a vertical extent of >200 m (16, 17). While the daytime occurrence of a single DSL is commonly observed, multiple scattering layers comprising different communi- The boundary between the mesopelagic zone and the bathypelagic zone contains The Deep Scattering layer – a layer of fish, squid, crustaceans etc, that migrate each day from the deep ocean to the shallows at night. Scientists noticed a huge, scattered sonar signal that was deep during the day and rose to shallower water as night fell.The 3.3 million km marine ecosystem around the North Pole, defined as the Central Arctic Ocean (CAO), is a blind spot on the map of the world's fish stocks. The CAO essentially comprises the permanently ice-covered deep basins and ridges outside the continental shelves, and is only accessible by ice-breakers. Traditional trawling for assessing fish …From siphonophores to deep scattering layers: uncertainty ranges for the estimation of global mesopelagic fish biomass Roland Proud1*, Nils Olav Handegard2, Rudy J. Kloser3, Martin J. Cox4, and ...Analysis of acoustic backscatter data and micronekton biomass displayed prominent near-surface night time and deep (>400 m) day time scattering layers associated with the diurnal vertical migration of the mesopelagic fauna. An intense and previously unreported aggregation of acoustic scatterers was detected in the depth range 150-300 m inside ....

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