Quantification of Chaoborus and small fish by mobile upward-looking echosounding

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F60077344%3A_____%2F19%3A00504821" target="_blank" >RIV/60077344:_____/19:00504821 - isvavai.cz</a>

Nalezeny alternativní kódy

RIV/60076658:12310/19:43899196

Výsledek na webu

<a href="https://www.jlimnol.it/index.php/jlimnol/article/view/jlimnol.2018.1837/1508" target="_blank" >https://www.jlimnol.it/index.php/jlimnol/article/view/jlimnol.2018.1837/1508</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.4081/jlimnol.2018.1837" target="_blank" >10.4081/jlimnol.2018.1837</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Quantification of Chaoborus and small fish by mobile upward-looking echosounding

Popis výsledku v původním jazyce

Chaoborus larvae inhabit frequently the water column of lakes, when they can be mistaken for small fish. Because larvae ascend up to the blind zone of downward-looking echo sounding at night, quantitative acoustic estimation of them is possible only with upward-looking approach. For this reason, the mobile hydroacoustic upward-looking system (120 and 38 kHz split-beam echosounder) in combination with a direct catch method (trawling) was tested to investigate the night community of invertebrates and juvenile fish in the surface layer of the Rimov reservoir (Czech Republic). In the target strength range of invertebrates (smaller than59 dB), the 38 kHz echosounder recorded only a small proportion of targets while the 120 kHz echosounder recorded distinct peaks corresponding to high densities of Chaoborus (target strength, TS range70 to60 dB, average TS66 to64 dB). At 120 kHz frequency, the TS distribution of smaller cohort of juvenile fish (<25 mm in length) overlapped the TS-distribution of Chaoborus. The number of these smaller juvenile fish was so small compared with the number of Chaoborus that they did not seriously bias acoustic Chaoborus estimate. The correlation between the density of Chaoborus with small contamination of juvenile fish larvae from trawling and acoustic recording made with the 120 kHz echosounder was high (R-2=0.88), but the acoustic densities from trace counting appeared to underestimate Chaoborus abundance when the density was >1.5 ind.m(-3).

Název v anglickém jazyce

Quantification of Chaoborus and small fish by mobile upward-looking echosounding

Popis výsledku anglicky

Chaoborus larvae inhabit frequently the water column of lakes, when they can be mistaken for small fish. Because larvae ascend up to the blind zone of downward-looking echo sounding at night, quantitative acoustic estimation of them is possible only with upward-looking approach. For this reason, the mobile hydroacoustic upward-looking system (120 and 38 kHz split-beam echosounder) in combination with a direct catch method (trawling) was tested to investigate the night community of invertebrates and juvenile fish in the surface layer of the Rimov reservoir (Czech Republic). In the target strength range of invertebrates (smaller than59 dB), the 38 kHz echosounder recorded only a small proportion of targets while the 120 kHz echosounder recorded distinct peaks corresponding to high densities of Chaoborus (target strength, TS range70 to60 dB, average TS66 to64 dB). At 120 kHz frequency, the TS distribution of smaller cohort of juvenile fish (<25 mm in length) overlapped the TS-distribution of Chaoborus. The number of these smaller juvenile fish was so small compared with the number of Chaoborus that they did not seriously bias acoustic Chaoborus estimate. The correlation between the density of Chaoborus with small contamination of juvenile fish larvae from trawling and acoustic recording made with the 120 kHz echosounder was high (R-2=0.88), but the acoustic densities from trace counting appeared to underestimate Chaoborus abundance when the density was >1.5 ind.m(-3).

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

40103 - Fishery

Projekt

Výsledek vznikl pri realizaci vícero projektů. Více informací v záložce Projekty.

Návaznosti

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Rok uplatnění

2019

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Journal of Limnology

ISSN

1129-5767

e-ISSN

—

Svazek periodika

78

Číslo periodika v rámci svazku

1

Stát vydavatele periodika

IT - Italská republika

Počet stran výsledku

11

Strana od-do

60-70

Kód UT WoS článku

000463363000006

EID výsledku v databázi Scopus

2-s2.0-85065888914