scholarly journals Comparing Fish Density and Echo Strength Distribution Recorded by Two Generations of Single Beam Echo Sounders

2019 ◽  
Vol 9 (10) ◽  
pp. 2041 ◽  
Author(s):  
Arne N. Linløkken ◽  
Frode Næstad ◽  
Kjell Langdal ◽  
Kjartan Østbye
Keyword(s):  
Salvelinus Alpinus ◽  
Arctic Charr ◽  
Strength Distribution ◽  
Target Strength ◽  
Fish Density ◽  
Fish Stock ◽  
Coregonus Lavaretus ◽  
Total Density ◽  
Single Beam ◽  
Two Generations

Hydroacoustic acquisition was performed by means of two different single beam systems, the Simradmodel EK15 from 2015 and the Simrad model EY-M from the 1980s to explore potential differences of fish density and target strength (TS) distribution between EK15 and EY-M-based estimates. The oligotrophic Lake Storsjøen (48 km2) with steep shores, was chosen for the survey. The pelagic fish stock is dominated by whitefish (Coregonus lavaretus L.), and, recently, illegally stocked smelt (Osmerus eperlanus L.), and a low proportion of Arctic charr (Salvelinus alpinus L.). The total density was estimated at two depth layers (18–32 and 32–48 m), and was quite similar for TS ≥ −56 dB: 755 and 498 fish ha−1, respectively for the EK15-based estimates and similarly 766 and 490 fish ha−1 for the EY-M estimate. Target strength distributions were similar for TS > −48 dB. The proportion of single fish detected with EK15 was negatively affected by the long pulse duration. Six acquisitions from 1986 to 2016 showed a dramatic increase of density of TS = −46 to −44 dB echoes (>10 cm) between 2013 and 2016. This was due to the growth of the introduced smelt population.

scholarly journals Factors determining parasite abundance in European perch, Perca fluviatilis, European whitefish, Coregonus lavaretus, and Arctic charr, Salvelinus alpinus, in an oligotrophic lake, southern Norway

2020 ◽  
Vol 40 ◽  
pp. 109-129
Author(s):  
Tom Robin Olk ◽  
Ann-Cecilie Henriksen ◽  
Solveig Irene Dolven ◽  
Mathias Leithe Haukø ◽  
Espen Lydersen ◽  
...  
Keyword(s):  
Salvelinus Alpinus ◽  
Arctic Charr ◽  
Perca Fluviatilis ◽  
Coregonus Lavaretus ◽  
Host Age ◽  
European Perch ◽  
Parasite Abundance ◽  
Perch Perca Fluviatilis ◽  
Southern Norway ◽  
Benthic Animals

Time and spatial variations in macroparasite status were investigated in European perch, Perca fluviatilis, European whitefish, Coregonus lavaretus, and Arctic charr, Salvelinus alpinus in Lake Norsjø (Southern Norway), based on gillnet fishing in three locations in the spring, summer, and fall 2018. In addition, length, weigth, age, sex, δ13C, and δ15N were determined. Parasite abundance was modelled using negative binomial generalized linear models in relation to fish metrics, season, and sampling location. The most prevalent parasite species were determined by the diet and habitat of the host. European perch was mainly infected by acanthocephalans, European whitefish mainly infected by acanthocephalans and cestodes, and Arctic charr mainly infected by cestodes. The most prevalent parasites in European perch are transmitted by benthic animals. Parasites in European whitefish are transmitted by both benthic animals and copepods, while the most prevalent parasites in Arctic charr are copepod transmitted. This corresponds well with the δ13C signatures in the three species, indicating that European perch primarily fed in the littoral zone (δ13C: -24.9 ± 2.5 ‰), Arctic charr in the pelagic and profundal zone (δ13C: -29.4 ± 1.1 ‰), while European whitefish both fed in the littoral and pelagic zone (δ13C: -28.3 ± 2.3 ‰) of Lake Norsjø. Individual abundances of parasites depended on host age, length, sex, δ15N, and season. Positive correlations between parasite abundance and host age, length, or trophic level measured as δ15N were most common, and occurred in all three host species. Many parasites accumulate with age, and larger hosts provide more diverse habitats for parasites.

Description of three new European cryptic species of Gyrodactylus Nordmann, 1832 supported by nuclear and mitochondrial phylogenetic characterization

2008 ◽  
Vol 53 (2) ◽  
Author(s):  
Jussi Kuusela ◽  
Marek Ziętara ◽  
Jaakko Lumme
Keyword(s):  
Salvelinus Alpinus ◽  
Arctic Charr ◽  
Rutilus Rutilus ◽  
Species Group ◽  
Nuclear Ribosomal Dna ◽  
Coregonus Lavaretus ◽  
Roach Rutilus Rutilus ◽  
Phylogenetic Characterization ◽  
5.8S Rdna ◽  
Rainbow Trout Oncorhynchus Mykiss

AbstractThree previously undescribed species of wageneri group of Gyrodactylus Nordmann, 1832 (subgenus Limnonephrotus, Gyrodactylidae, Monogenoidea) related to G. lavareti Malmberg, 1957 are described here. G. pomeraniae sp. nov. was found on roach (Rutilus rutilus) in Poland and Belgium, G. ouluensis sp. nov. on roach in Finland and G. salvelini sp. nov. on Arctic charr (Salvelinus alpinus) in the Lake Inari, Finland. A molecular redescription of G. lavareti on Coregonus lavaretus is also presented, and G. bliccensis on Alburnus alburnus from river Morava, Czech Republic is included in the phylogenetic analysis. In addition, a hybrid clone of maternal G. pomeraniae sp. nov. and paternal G. lavareti found on farmed rainbow trout (Oncorhynchus mykiss) is characterized. The molecular species description was based on the complete CO1 gene of the mitochondrial DNA, and on phylogenetic comparison of the internal transcribed spacer segment (ITS1-5.8S rDNA-ITS2) of nuclear ribosomal DNA. The species hosted by cyprinids were basal in the phylogeny rooted by numerous relatives of wageneri-species group.

Habitat use and diet of sympatric Arctic charr (Salvelinus alpinus) and whitefish (Coregonus lavaretus) in five lakes in southern Norway: not only interspecific population dominance?

Hydrobiologia ◽  
2010 ◽  
Vol 650 (1) ◽  
pp. 27-41 ◽  
Author(s):  
Odd Terje Sandlund ◽  
Jon Museth ◽  
Tor F. Næsje ◽  
Sigurd Rognerud ◽  
Randi Saksgård ◽  
...  
Keyword(s):  
Habitat Use ◽  
Salvelinus Alpinus ◽  
Arctic Charr ◽  
Coregonus Lavaretus ◽  
Southern Norway

Visual pigments of Arctic charr (Salvelinus alpinus (L.)) and whitefish (Coregonus lavaretus (L.)) morphs in subarctic lakes

Hydrobiologia ◽  
2015 ◽  
Vol 783 (1) ◽  
pp. 223-237 ◽  
Author(s):  
K. K. Kahilainen ◽  
T. Smura ◽  
R. Knudsen ◽  
P.-A. Amundsen ◽  
M. Jokela-Määttä ◽  
...  
Keyword(s):  
Salvelinus Alpinus ◽  
Arctic Charr ◽  
Visual Pigments ◽  
Coregonus Lavaretus ◽  
Subarctic Lakes

scholarly journals Past, present and future of the fish community of Lake Orta (Italy), one of the world’s largest acidified lakes

2016 ◽  
Vol 75 (s2) ◽  
Author(s):  
Pietro Volta ◽  
Norman D. Yan ◽  
John M. Gunn
Keyword(s):  
Fish Species ◽  
Salmo Trutta ◽  
Fish Community ◽  
Cold Water ◽  
Salvelinus Alpinus ◽  
Arctic Charr ◽  
Anguilla Anguilla ◽  
Coregonus Lavaretus ◽  
Cottus Gobio ◽  
Sampling Campaign

<p>Since 1926, the fishes in Lake Orta, one of Italy’s deepest natural lakes, were heavily damaged by profundal hypoxia and acidification linked to oxidation of ammonia from industrial effluents and by industrial metal pollution. Of the original 28 fish species, only perch survived the lake’s contamination. Recently, the water quality of the lake has been largely restored by reductions in pollutant inputs, and a massive liming intervention. These interventions restored fish habitat, but it is unclear whether the recent fish reintroductions were successful, and the present status of the fish community is unknown.  Here we reviewed the history of the Lake Orta fish assemblage. Using an extensive 2014 sampling campaign, we compared the present fish community to both its pre-pollution composition and to the assemblages of nearby un-polluted, but otherwise similar lakes, Lake Mergozzo and Lake Maggiore. While nearshore fish density now appears normal in lake Orta, the open water community remains impoverished both in numbers and in species. Epilimnetic and hypolimnetic benthic nets were dominated by perch and roach in all the three lakes, but the catch of pelagic nets differed among lakes. Perch (<em>Perca fluviatilis)</em>, rudd (<em>Scardinius erythrophthalmus)</em> and brown trout (<em>Salmo trutta</em>) dominated in Lake Orta while shad (<em>Alosa fallax lacustris</em>) and coregonids (<em>Coregonus</em> spp.) were dominant in the open waters of the other two lakes, but missing from Lake Orta.  Many fully or partially migratory species, including marble trout (<em>Salmo trutta marmoratus)</em>, eel (<em>Anguilla Anguilla)</em> and barbel (<em>Barbus plebejus)</em> were also missing from Lake Orta, a consequence of their initial extirpation and blocked re-colonization routes along the River Strona. In comparison with both pre-pollution and contemporary reference data, the fish community of Lake Orta has not been rehabilitated. The recovery of the littoral community is complete, but cold water species such as burbot (<em>Lota lota), </em>Arctic charr (<em>Salvelinus alpinus)</em> and bullhead (<em>Cottus gobio)</em> are still lacking, as are the pelagic zooplanktivores European whitefish (<em>Coregonus lavaretus)</em> and shad, which dominate offshore communities in the reference lakes, as they did a century ago in Lake Orta.  To propose priorities for fish community rehabilitation in Lake Orta, we categorized the conservation, ecological and fishing values of each missing fish species in the lake, and evaluated the cost and probability of success of the needed intervention for each species. This analysis indicated that rehabilitation of shad and European whitefish should receive highest priority.</p>

Fish density and target strength distribution of single fish echoes in varying light conditions with single and split beam echosounding and trawling

Hydrobiologia ◽  
2016 ◽  
Vol 780 (1) ◽  
pp. 113-124 ◽  
Author(s):  
Juha Jurvelius ◽  
Timo J. Marjomäki ◽  
Heikki Peltonen ◽  
Andrei Degtev ◽  
Eva Bergstrand ◽  
...  
Keyword(s):  
Strength Distribution ◽  
Target Strength ◽  
Fish Density ◽  
Light Conditions

scholarly journals 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)

2016 ◽  
Vol 7 (1) ◽  
pp. 69
Author(s):  
Henry M. Manik ◽  
Indah Nurkomala
Keyword(s):  
Data Processing ◽  
Measurement Data ◽  
Target Strength ◽  
Fish Density ◽  
Fish Stock ◽  
Fish Length ◽  
Accuracy Measurement ◽  
Echo Detection ◽  
Biomass Analysis ◽  
Echo Sounder

<p>ABSTRACT<br /><br />Echoes from two targets cannot be distinguished if two targets are located in the same range. This will cause an error in some analysis process such as analysis to estimate fish density. Therefore, a high quality of single echo detection (SED) is needed to minimalize the overlapping echo. The aim of this study is to estimate target strength and density of the fish / stock using different SED criteria using split beam echo sounder in Pari Island. Data processing used was Sonar5-pro software for SED measurement. Data processing stages were producing new SED-echogram and executing biomass analysis using Sv/TS Scaling method. SED criteria setting are SED-ori, SED-d, SED-f, and SED-m. Using different SED criteria in biomass analysis produces different target strength and density of fish. Number of single fish detection and fish size proportion in each SED criteria setting is different. Distribution of Target Strength (TS) is dominated by -70 dB to -61 dB, fish length 0,8-2,2 cm, and density 1.000-5.000 fish/ha. The suggested SED criteria are SED-f for a high accuracy measurement.<br /><br />Keywords: fish density, Pari Island, single echo detection, target strength, split beam echo sounder</p><p>-------<br /><br />ABSTRAK<br /><br />Gema 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.<br /><br />Kata kunci: densitas ikan, Pulau Pari, single echo detection, target strength, split beam echo sounder</p>

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