scholarly journals Delineating the habitat of demersal fish assemblages with acoustic seabed technologies

2011 ◽  
Vol 68 (9) ◽  
pp. 1973-1985 ◽  
Author(s):  
Jeroen van der Kooij ◽  
Sven Kupschus ◽  
Beth E. Scott
Keyword(s):  
Species Composition ◽  
Fish Assemblages ◽  
Demersal Fish ◽  
Single Beam ◽  
Explanatory Variables ◽  
Acoustic Data ◽  
Spatial Management ◽  
Fish Habitats ◽  
The Relationship ◽  
Demersal Species

Abstract van der Kooij, J., Kupschus, S., and Scott, B. E. 2011. Delineating the habitat of demersal fish assemblages with acoustic seabed technologies. – ICES Journal of Marine Science, 68: 1973–1985. Habitats influence species distribution and, although the seabed is an important habitat factor for demersal species, traditional sampling methods often provide no practical solution to investigating the seabed over large areas. The ability of a multivariate method that utilizes single-beam acoustic seabed data combined with species composition data to define demersal fish habitats was tested. The best model explained 19.4% of the variance observed in the species data and was robust between years. Ten biotopes were identified, each containing species that, either alone or in combination with others, were indicative of that biotope. Using unclassified acoustic seabed data as explanatory variables, discrepancies between the numbers of acoustically distinct classes and species assemblages, as previously reported in the literature, were avoided, while utilizing their relationship with community structure. The study focused on the relationship between simultaneously recorded species composition and seabed data from fishing stations, but because continuous acoustic data along the survey tracks were available between stations, the model could be used to predict the spatial extent of the biotopes. Although the method was developed with the eventual aim of providing a meaningful foundation to the spatial management of mixed fisheries, it could also contribute to applications in spatial planning.

scholarly journals Extraction and comparison of acoustic backscatter from a calibrated multi- and single-beam sonar

2003 ◽  
Vol 60 (3) ◽  
pp. 669-677 ◽  
Author(s):  
Gary D Melvin ◽  
Norman A Cochrane ◽  
Yanchao Li
Keyword(s):  
Acoustic Properties ◽  
Target Strength ◽  
Acoustic Backscatter ◽  
Biomass Estimation ◽  
Single Beam ◽  
Acoustic Data ◽  
Powerful Analytical Tool ◽  
Acoustic Target ◽  
Element Array ◽  
The Relationship

Abstract Multi-beam sonar is potentially a powerful analytical tool for investigating the acoustic properties and behaviour of fish in relation to quantitative fisheries research. The SIMRAD SM2000 is a 200 kHz multi-beam sonar employing an 80-element array to transmit and synthesize, electronically, 128 receive beams (20°×2.2°) over a 180° arc simultaneously. Once calibrated, such systems enable the extraction of acoustic target strength and volume backscattering from an extended 3D ocean volume. We present an overview of the theoretical framework for the calibration of a multi-beam sonar, and then compare the acoustic backscatter from a calibrated single-beam 50 kHz echosounder with selected beams from a sphere-calibrated multi-beam sonar. Both systems recorded acoustic data from Atlantic herring contained within a weir, as the fish passed beneath the transducers. Specifically, we examine the relationship between the area-backscattering strength (Sa) from the single-beam system with the nadir beam (beam 63) of the SM2000 sonar. In addition, data are presented on the observed variability in Sa with target aspect for off-vertical angles from 15° to 60° in 15° intervals. Non-standard synthesized SM2000 beam widths are explored for both calibration and field datasets. The implications for biomass estimation are also discussed.

scholarly journals The demersal fish assemblages of the infra and circalittoral coastal rocky bottoms of the Aeolian Archipelago (Central Mediterranean Sea) studied by Remotely Operated Vehicle (ROV)

2020 ◽  
Author(s):  
IVAN CONSALVO ◽  
GABRIELE La MESA ◽  
SIMONEPIETRO CANESE ◽  
MICHELA GIUSTI ◽  
EVA SALVATI ◽  
...  
Keyword(s):  
Species Richness ◽  
Species Composition ◽  
Fish Assemblages ◽  
Demersal Fish ◽  
Total Density ◽  
Depth Range ◽  
Remotely Operated Vehicle ◽  
Depth Ranges ◽  
Aeolian Archipelago ◽  
Rocky Bottoms

Demersal fish assemblages on the rocky bottoms of the Aeolian Archipelago were investigated using a Remotely Operated Vehicle (ROV) within the framework of research activities aimed at drawing up the zoning proposal of a new Italian national marine protected area. Visual assessments were conducted around the seven main islands by means of a total of 36 ROV transects. Video material was divided into 3 parts belonging to 3 Archipelago sectors (Western, Central and Eastern) and into 3 depth ranges (20-50, 51-120, 121-190). Thirty taxa of teleosts (29 species and 1 genus) belonging to 16 families were recorded. The assemblages were numerically dominated by some schooling fishes, such as Anthias anthias, Callanthias ruber and Chromis chromis, which exhibited a depth related partitioning of space, and three non-gregarious species, i.e. Serranus cabrilla, Coris julis and Lappanella fasciata. In terms of species composition, the assemblages observed in the sectors of the Archipelago largely overlapped. No significant sector-related differences were detected in fish species richness, diversity and total density. Species composition and the investigated assemblage parameters were significantly affected by depth. The pattern of variation in species richness among depth ranges changed depending on the archipelago sectors. No significant interaction between the factors depth range and sector was observed for species diversity and total density. Diversity values at 20-50 and 121-190 m depth were similar and significantly higher than that at 51-120 m depth. Fish total density showed a clear decreasing trend with increasing depth, though significant differences were detected between the 20-50 and 51-120 depth layers and the deepest one. Overall, the demersal fish assemblage of the Aeolian Archipelago was poorly diversified and depleted, most likely due to overfishing. This information highlighted the importance of the adoption of specific measures aimed at the recovery of overexploited resources and the restoration of the whole marine ecosystems.

scholarly journals KEPADATAN DAN STRATIFIKASI KOMPOSISI SUMBER DAYA IKAN DEMERSAL DI LAUT CINA SELATAN (WPP – NRI 711)

2017 ◽  
Vol 22 (3) ◽  
pp. 161
Author(s):  
Robet Perangin Angin ◽  
Sulistiono Sulistiono ◽  
Rahmat Kurnia ◽  
Achmad Fahrudin ◽  
Ali Suman
Keyword(s):  
South China Sea ◽  
Species Composition ◽  
South China ◽  
Demersal Fish ◽  
The South China Sea ◽  
The South ◽  
Fish Stocks ◽  
Acoustic Data ◽  
China Sea ◽  
Fish Resources

Informasi distribusi kepadatan stok dan komposisi ikan demersal sangat penting untuk diketahui sebagai bahan masukan guna keberhasilan pengelolaan perikanan. Untuk itu dilakukan penelitian yang bertujuan untuk mengetahui komposisi, kepadatan stok dan sebaran sumber daya ikan demersal di Laut Cina Selatan. Penelitian dilaksanakan pada Mei sampai Juni 2015 dengan menggunakan scientific echosounder BIOSONICS DT-X dan frekuensi 120 KHz. Untuk verifikasi data akustik terutama komposisi jenis dilakukan pengoperasian trawl. Hasil penelitian menunjukkan komposisi jenis ikan demersal di Laut Cina Selatan meliputi 147 spesies dari 55 famili. Stratifikasi komposisi dikedalaman 20-30 m, 30-40 m, 40-50 m, 50-60 m, dan 60-70 m masing masing didominasi oleh ikan dari famili Leiognathidae, Lutjanidae, Nemipteridae, Tetraodontidae, dan Serranidae. Estimasi kepadatan stok sumber daya ikan demersal di Laut Cina Selatan berkisar antara 0,16 – 2,85 ton/km2 dengan rata-rata kepadatan 1,05 ton/km2. Information about density distribution and composition of demersal fish stocks is very important to be known as an input for the success of fisheries management. Current research aimed to determine the composition, stock density and distribution of demersal fish resources in the South China Sea. The research was conducted in May to June 2015 using scientific echosounder BIOSONICS DT-X and frequency of 120 KHz. Trawler sampling was done to verify the acoustic data, especially for species composition. The results show that the species composition of demersal fish in the South China Sea consisted of 147 species of 55 families. The stratification of the composition at the respective depth of 20-30 m, 30-40 m, 40-50 m, 50-60 m and 60-70 m, were dominated by fish families of Leiognathidae, Lutjanidae, Nemipteridae, Tetraodontidae, and Serranidae. The estimated stock density of demersal fish resources in the South China Sea ranged from 0.16 to 2.85 tonnes/km2 with the average of 1.05 tonnes / km2.     

scholarly journals Assessing the impact of fisheries on demersal fish assemblages of the Mauritanian continental shelf, 1987–1999, using dominance curves

2005 ◽  
Vol 62 (3) ◽  
pp. 380-383 ◽  
Author(s):  
Didier Jouffre ◽  
Cheikh A. Inejih
Keyword(s):  
Species Composition ◽  
Continental Shelf ◽  
Fish Assemblages ◽  
Demersal Fish ◽  
Octopus Vulgaris ◽  
Taxonomic Information ◽  
Associated Species ◽  
The Impact ◽  
Trawl Surveys

Abstract The assemblages of demersal fish and associated species of the Mauritanian continental shelf are characterized on the basis of annual trawl surveys conducted during the period 1987–1999. Species composition is dominated by exploited species (Dentex spp., Pagellus bellottii, and Octopus vulgaris). Dominance curves (Abundance Biomass Comparison plots) were used to evaluate the impact of fisheries, which have increased in magnitude over several decades. The diagnosis of a “stressed” assemblage seems to converge with the results of a similar study conducted off Senegal, but here there was no trend in impact during the period of study. The sensitivity of the present results to the various ways of considering the available taxonomic information is also analysed.

scholarly journals Diversidad y distribución de peces y su relación con variables ambientales, en el sur del Golfo de México

2017 ◽  
Vol 66 (1) ◽  
pp. 438
Author(s):  
Daniel Torrruco ◽  
Alicia González ◽  
Ángel Torruco González
Keyword(s):  
Spatial Distribution ◽  
Fish Species ◽  
Fish Assemblages ◽  
Management Strategies ◽  
Mesh Size ◽  
Demersal Fish ◽  
Average Weight ◽  
Important Species ◽  
Spatial Management ◽  
River Mouths

The Campeche Sound has a high heterogeneity of habitats, great fish species diversity, and a strong presence of oil and fishing industries. Even though some information of bento-demersal fish of the area is available, this has been focused on some economically important species. This way, our objective of this study was to obtain the ichthyofaunal spatial distribution and its relationship with this study were were to obtain updated information on a complete local fish species spatial distribution and their relationship with environmental elements, this will improve the baseline to evaluate the potential impact of future oil and fishing developments. For this, our approach used a database obtained in 2010, with a capture made in 54 sites with standard shrimp fishing trawls (60 feet long x 1¼ in. mesh size; towing time 30 min, 2 knots; 19 to 600 m depth) in the Campeche Sound. Our data analysis included: dominance, diversity, equity, assemblies, spatial management and a landscape representation of the area. We collected a total of 33 315 fish, of 80 families, 138 genera and 193 species, that corresponded to 2 502 438 kg. The fish classes Chondrichthyes and Actinopterygii predominated. A total of 17 were dominant, associated to sandy and muddy bottoms, although were species of estuarine environments, reef and pelagic habitats. Averaged diversity (H') was of 3.2 bits/individuals. In decreasing diversity order, the common fish belong to Perciformes (84 species), Pleuronectiformes (23), Scorpaeniformes (15) and Tetraodontiformes (14); in the same way, the higher richness families were Sciaenidae (15 species), Paralichthyidae (12), Carangidae (10), and Triglidae and Synodontidae (7). Most common genuses were Prionotus (6 species), Citharichthys and Sphoeroides (4 each). Per each station, richness varied between 3 and 56 species, with an average weight of 46 kg. Fish assemblage composition was different among habitats and areas, with divergent management strategies. Landscape analysis defines nodules of high density and diversity that corresponded to river mouths, lagoons and reef areas fish assemblages. Of the relation between variables and community descriptors, only the organic carbon was significant for both abundance and biomass, the REDOX for the species richness and the other variables were not important.

scholarly journals Analysis of demersal fish assemblages of the Tuscany and Latium coasts (north-western Mediterranean)

2002 ◽  
Vol 66 (S2) ◽  
pp. 233 ◽  
Author(s):  
Franco Biagi ◽  
Paolo Sartor ◽  
Gian Domenico Ardizzone ◽  
Paola Belcari ◽  
Andrea Belluscio ◽  
...  
Keyword(s):  
Species Composition ◽  
Continental Shelf ◽  
Fish Assemblages ◽  
Demersal Fish ◽  
Western Mediterranean ◽  
Similar Species ◽  
The European Union ◽  
The North ◽  
North Western ◽  
Trawl Surveys

A four-year time series (1994-1997) of groundfish trawl surveys performed within the European Union Project MEDITS (Mediterranean International Trawl Surveys), was analysed to identify and describe the fish assemblages along the continental shelf and slope of Tuscany and Latium (Italy), in the north-western Mediterranean. Cluster analysis was used to group samples with similar species composition in terms of abundance, biomass and frequency of occurrence. Results allowed the identification of four to five broad assemblages along the depth gradient: a strictly coastal group (< 50 m depth), two groups in the upper and lower part of the continental shelf (essentially 50-200 m), an epibathyal group (200-450 m) and a group derived from hauls made at depths greater than 450 m. Each assemblage corresponded to a faunistic association with relatively homogeneous and persistent species composition, biomass and density indices.

scholarly journals Can the precision of bottom trawl indices be increased by using simultaneously collected acoustic data? The Barents Sea experience

2007 ◽  
Vol 64 (10) ◽  
pp. 1390-1402 ◽  
Author(s):  
Vidar Hjellvik ◽  
Dag Tjøstheim ◽  
Olav Rune Godø
Keyword(s):  
Variance Reduction ◽  
Barents Sea ◽  
Demersal Fish ◽  
Auxiliary Variable ◽  
Unexpected Result ◽  
Explanatory Variables ◽  
Acoustic Data ◽  
The Barents Sea ◽  
Main Variable ◽  
A Minor

Acoustic data are recorded continuously during the winter survey for demersal fish in the Barents Sea. This paper presents a method for using the information from the acoustic recordings between trawl stations in an attempt to increase the precision of the trawl estimate. The method is related to the double-sampling regression estimation, in which information from a frequently sampled auxiliary variable (e.g., acoustics) that is correlated with the main variable (e.g., trawl) is used for the purpose of increasing the precision in the estimate of the population mean of the main variable. The version presented here allows for additional explanatory variables and for autocorrelation in the main and auxiliary variables. However, when applied to the Barents Sea data, only a minor variance reduction is obtained. The main reasons for this are a high autocorrelation in the acoustic data and a relatively low correlation between trawl and acoustics on trawl stations. Another unexpected result is that the acoustic density during trawling is significantly higher than between trawl stations.

The Relationship between Mobility and COVID-19 in Germany: Modeling Case Occurrence using Apple's Mobility Trends Data

2021 ◽  
Author(s):  
Mark David Walker ◽  
Mihály Sulyok
Keyword(s):  
Generalized Additive Models ◽  
Information Criterion ◽  
Additive Models ◽  
Online Data ◽  
German Government ◽  
Explanatory Variables ◽  
Mobility Data ◽  
Community Mobility ◽  
The Relationship ◽  
Potential Use

Abstract Background Restrictions on social interaction and movement were implemented by the German government in March 2020 to reduce the transmission of coronavirus disease 2019 (COVID-19). Apple's “Mobility Trends” (AMT) data details levels of community mobility; it is a novel resource of potential use to epidemiologists. Objective The aim of the study is to use AMT data to examine the relationship between mobility and COVID-19 case occurrence for Germany. Is a change in mobility apparent following COVID-19 and the implementation of social restrictions? Is there a relationship between mobility and COVID-19 occurrence in Germany? Methods AMT data illustrates mobility levels throughout the epidemic, allowing the relationship between mobility and disease to be examined. Generalized additive models (GAMs) were established for Germany, with mobility categories, and date, as explanatory variables, and case numbers as response. Results Clear reductions in mobility occurred following the implementation of movement restrictions. There was a negative correlation between mobility and confirmed case numbers. GAM using all three categories of mobility data accounted for case occurrence as well and was favorable (AIC or Akaike Information Criterion: 2504) to models using categories separately (AIC with “driving,” 2511. “transit,” 2513. “walking,” 2508). Conclusion These results suggest an association between mobility and case occurrence. Further examination of the relationship between movement restrictions and COVID-19 transmission may be pertinent. The study shows how new sources of online data can be used to investigate problems in epidemiology.

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