Comparison of hydroacoustic estimates with fish census in shallow Malta Reservoir – which TS/L regression to use in horizontal beam applications?

Godlewska, M.; Frouzová, Jaroslava; Kubečka, Jan; Wiśniewolski, Wiesław; Szlakowski, Jacek

doi:10.1016/j.fishres.2011.11.023

Cited by 22 publications

(11 citation statements)

References 33 publications

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“…acoustic TS and A) and subsequent conversions (i.e. converting TS to L, L to M and then, A and M to B), which relationships however vary by fish species and may change with sampling circumstances (Didrikas and Hansson, 2004;Boswell et al, 2008;Godlewska et al, 2012). Accordingly, the accuracy of acoustics-derived size distribution and biomass data can be variable, and generally, it is unknown.…”

Section: Discussionmentioning

confidence: 99%

“…Further, as typically we do not know the orientation of fish relative to the sound-beam axis, fish size assessment is even more problematic in horizontal acoustics. Since we had robust numbers of single echoes detected and there was not any indication on that fish were not randomly oriented, we used the de-convolution procedure to convert TS values to L values (Kubečka et al, 1994;Godlewska et al, 2012). However, if a deviation from the randomness of the orientation of the fish occurs, estimated L distribution and perforce, the assessed biomass will be biased as well.…”

Section: Discussionmentioning

confidence: 99%

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Relationship between horizontal hydroacoustic stock estimates and gillnet catches of surface-oriented fish in shallow Lake Balaton (Hungary)

György

Tátrai

Specziár

2012

Knowl. Managt. Aquatic Ecosyst.

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Key-words:gillnet, side-looking hydroacoustics, comparability of data, Alburnus alburnus, shallow lakeWe examined whether gillnetting and hydroacoustics provide comparable relative fish density and fish size distribution estimates in the uppermost water layer of a shallow turbid lake and whether the inclusion of environmental and stock parameters could improve comparability of data between different gears. According to gillnetting, most fish shorter than 14 cm in total length were Alburnus alburnus, and most fish longer than 14 cm were Pelecus cultratus. Size distributions and median sizes obtained from gillnetting and acoustics differed. Pure acoustics-derived density estimates accounted for only <8.8% of the variation in the gillnet catch by number and no correlation was found in biomass indices. Most variances observed in the gillnet catch-per-unit-effort data were associated with water transparency, none of the other investigated variables had significant explanatory power. We conclude that the feasibility of establishing a powerful model describing the relationship between fish density estimates of gillnetting and acoustics is low in shallow and turbid habitats, and it might be successful only if the crucial sampling and environmental parameters affecting catch efficiency of gillnets and post-processing of acoustic data are considered. This study cautions again that gillnetting should be used carefully to analyse trends of fish abundance. RÉSUMÉRelation entre les estimations horizontales hydroacoustiques du stock et les captures au filet maillant de poissons de surface en eaux peu profondes du lac Balaton (Hongrie) Mots-clés :filet maillant, hydroacoustique latérale, comparabilité des données, Alburnus alburnus, lac peu profond Nous avons examiné si les filets maillants et l'hydroacoustique fournissent des données comparables de la densité des poissons et des estimations de distribution en taille des poissons dans la couche d'eau supérieure d'un lac peu profond trouble et si l'inclusion de paramètres environnementaux et du stock de poissons pourrait améliorer la comparabilité des données entre les différents engins. Selon la pêche au filet maillant, la plupart des poissons de longueur totale inférieure à 14 cm étaient Alburnus alburnus, et la plupart des poissons de plus de 14 cm étaient Pelecus cultratus. Les distributions de taille et les tailles médianes obtenues à partir des filets maillants et de l'acoustique sont différentes. Les estimations dérivées de la seule densité acoustique ne représentaient que moins de 8,8 % de la variation des captures au filet maillant en nombre et aucune corrélation

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Relationship between horizontal hydroacoustic stock estimates and gillnet catches of surface-oriented fish in shallow Lake Balaton (Hungary)

György

Tátrai

Specziár

2012

Knowl. Managt. Aquatic Ecosyst.

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“…To recalculate fish numerical density into fish biomass, the relationship between the acoustical size TS in dB and fish length in centimeters is required. Frouzova's regression for pooled common European species was used (Frouzova, 2005), as this was shown to give the best biomass estimate in another Polish lowland reservoir (Godlewska et al, 2012). With respect to the locations of the 14 stations for each sampling point, each transect length was divided into three equal sections (so-called integration intervals), and the fish abundance estimated for each section was assumed to correspond to a given station.…”

Section: Hydroacoustic Measurements and Fish Gillnettingmentioning

confidence: 99%

Relationships among cyanobacteria, zooplankton and fish in sub-bloom conditions in the Sulejow Reservoir

et al. 2017

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The occurrence of cyanobacteria is particularly characteristic of shallow eutrophic waters, and they often form massive 'blooms' that can affect aquatic invertebrates and fish. However, even a low abundance of cyanobacteria can be hazardous to aquatic organisms, due to the production of toxic metabolites. The aim of this study was to investigate the relationship between cyanobacteria and their toxicity (biological activity) towards zooplankton and fish communities, when only low concentrations of cyanobacterial chlorophyll a (less than 20 μg L -1 ) are detected, i.e. in sub-bloom conditions. Measurements were performed in Sulejow Reservoir (Central Poland), a shallow, lowland, eutrophic reservoir, in which cyanobacterial blooms occur regularly. Fish were assessed using echo-sounding (distribution) and by gillnetting (species composition). Simultaneously, zooplankton, cyanobacteria and physicochemical characteristics were studied at 14 stations situated along hydroacoustic transects. Parameters that characterized the cyanobacteria (cyanobacterial chlorophyll a concentration, the number of 16S rRNA and the mcyA gene copies and microcystin (MC) concentration) were consistently correlated (based on a principal component analysis), and the highest values were found in the downstream region of the study area. This 'cyano-complex' was also positively correlated with oxygen concentration, pH and phosphate levels, but was negatively correlated with temperature and the concentrations of nitrates and nitrites. In Sulejow Reservoir in 2013 the biomass of large zooplankton filter feeders decreased along with increasing MC concentration and fish densities, while small filter feeders did not present such relationships with regards to fish densities. Fish abundance tended to decrease at stations with a lower abundance of cyanobacteria and with growing toxic genotype copies and MC concentration.

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“…Beam clipping berfungsi untuk mendeteksi yang bukan target. Jika beam rectangular (kotak) dipilih, deteksi di luar kotak yang ditentukan akan dipotong (Jech 2011;Godlewska et al 2012).…”

Section: Prosedur Single Echo Detectionunclassified

PENGUKURAN TARGET STRENGTH DAN STOK IKAN DI PERAIRAN PULAU PARI MENGGUNAKAN METODE SINGLE ECHO DETECTOR (Measurement of Target Strength and Fish Stock in Pari Islands Seawaters Using Single Echo Detector Method)

Manik¹,

Nurkomala²

2016

Jurnal Marfis

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Echoes from two targets cannot be distinguished if two targets are located in the same ABSTRAKGema dari dua target tidak dapat dipisahkan jika kedua target berada dalam jarak yang sama. Hal ini menyebabkan terjadinya kesalahan dalam proses pengolahan data seperti analisis untuk mengestimasi densitas atau stok ikan. Oleh karena itu diperlukan metode single echo detection (SED) dengan kualitas tinggi untuk mereduksi gema yang tumpang tindih. Tujuan penelitian ini adalah mengestimasi target strength dan densitas ikan menggunakan pengaturan kriteria SED yang berbeda. Data yang digunakan merupakan data split beam echosounder di perairan Pulau Pari pada bulan Juni 2014. Pengolahan data menggunakan perangkat lunak Sonar5-pro. Tahapannya terdiri dari pembuatan SED-echogram baru dan analisis biomassa menggunakan metode Sv/TS Scaling. Pengaturan kriteria SED yang digunakan adalah SED-ori, SED-d, SED-f, dan SED-m. Penggunaan pengaturan kriteria SED yang berbeda dalam analisis biomassa menghasilkan nilai target strength dan densitas ikan yang berbeda. Jumlah ikan tunggal yang terdeteksi dan proporsi ukuran ikan juga berbeda pada tiap pengaturan kriteria SED. Dominasi sebaran target strength adalah -70 dB sampai dengan -61 dB (small), ukuran panjang ikan 0,8-2,2 cm (small), dan densitas 1.000-5.000 fish/ha. Pengaturan kriteria SED yang disarankan adalah SED-f karena memiliki akurasi tinggi.Kata kunci: densitas ikan, Pulau Pari, single echo detection, target strength, split beam echo sounder

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Comparison of hydroacoustic estimates with fish census in shallow Malta Reservoir – which TS/L regression to use in horizontal beam applications?

Cited by 22 publications

References 33 publications

Relationship between horizontal hydroacoustic stock estimates and gillnet catches of surface-oriented fish in shallow Lake Balaton (Hungary)

Relationship between horizontal hydroacoustic stock estimates and gillnet catches of surface-oriented fish in shallow Lake Balaton (Hungary)

Relationships among cyanobacteria, zooplankton and fish in sub-bloom conditions in the Sulejow Reservoir

PENGUKURAN TARGET STRENGTH DAN STOK IKAN DI PERAIRAN PULAU PARI MENGGUNAKAN METODE SINGLE ECHO DETECTOR (Measurement of Target Strength and Fish Stock in Pari Islands Seawaters Using Single Echo Detector Method)

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