Hydroacoustic target strength vs. fish length revisited: Data of caged, free-swimming European whitefish (Coregonus lavaretus L.) suggest a bi-phasic linear relationship under a limited range of tilt angles

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F60077344%3A_____%2F20%3A00538913" target="_blank" >RIV/60077344:_____/20:00538913 - isvavai.cz</a>

Výsledek na webu

<a href="https://doi.org/10.1016/j.fishres.2020.105620" target="_blank" >https://doi.org/10.1016/j.fishres.2020.105620</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1016/j.fishres.2020.105620" target="_blank" >10.1016/j.fishres.2020.105620</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Hydroacoustic target strength vs. fish length revisited: Data of caged, free-swimming European whitefish (Coregonus lavaretus L.) suggest a bi-phasic linear relationship under a limited range of tilt angles

Popis výsledku v původním jazyce

To develop specific target strength (TS) fish length relationships using 38 kHz and 120 kHz split beam echosounders, we measured TS (dB) in five size groups (5-59 cm total length) of European whitefish (Coregonus lavaretus) swimming freely in a net cage of 4m diameter and 8m height. For 120 kHz, we deployed down-looking (dorsal aspect) as well as upwards-looking (ventral aspect) transducers, whereas 38 kHz measurements were taken for the dorsal aspect only. The ventral aspect dataset revealed stronger TS values especially for the larger length classes. The dorsal aspect datasets of both frequencies were not significantly different across all lengths and both showed a steep increase of the relationship in small sizes (5-20 cm) which levelled off in the larger sizes (> 20 cm). For 120 kHz the slope of a linear regression of TS vs. log fish length was 29.8 for fish between 5-20 cm (much higher than the generally proposed slope of 20), while in fish > 20 cm the slope was 10.7 which is far below the generally proposed value. We advocate considering a potential bi-phasic linear regression of the log length TS relationship for all species whenever a large size range of fish is studied, encompassing significant proportions below and above approximately 20 cm total length.

Název v anglickém jazyce

Hydroacoustic target strength vs. fish length revisited: Data of caged, free-swimming European whitefish (Coregonus lavaretus L.) suggest a bi-phasic linear relationship under a limited range of tilt angles

Popis výsledku anglicky

To develop specific target strength (TS) fish length relationships using 38 kHz and 120 kHz split beam echosounders, we measured TS (dB) in five size groups (5-59 cm total length) of European whitefish (Coregonus lavaretus) swimming freely in a net cage of 4m diameter and 8m height. For 120 kHz, we deployed down-looking (dorsal aspect) as well as upwards-looking (ventral aspect) transducers, whereas 38 kHz measurements were taken for the dorsal aspect only. The ventral aspect dataset revealed stronger TS values especially for the larger length classes. The dorsal aspect datasets of both frequencies were not significantly different across all lengths and both showed a steep increase of the relationship in small sizes (5-20 cm) which levelled off in the larger sizes (> 20 cm). For 120 kHz the slope of a linear regression of TS vs. log fish length was 29.8 for fish between 5-20 cm (much higher than the generally proposed slope of 20), while in fish > 20 cm the slope was 10.7 which is far below the generally proposed value. We advocate considering a potential bi-phasic linear regression of the log length TS relationship for all species whenever a large size range of fish is studied, encompassing significant proportions below and above approximately 20 cm total length.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10618 - Ecology

Projekt

<a href="/cs/project/GAP504%2F12%2F1186" target="_blank" >GAP504/12/1186: Hydroakustické rozlišení ryb od bublin a kvantifikace emisí metanových bublin z přehrad mírného pásma</a><br>

Návaznosti

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

Rok uplatnění

2020

Kód důvěrnosti údajů

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

Název periodika

Fisheries Research

ISSN

0165-7836

e-ISSN

—

Svazek periodika

229

Číslo periodika v rámci svazku

5

Stát vydavatele periodika

NL - Nizozemsko

Počet stran výsledku

10

Strana od-do

1-10

Kód UT WoS článku

000539099200024

EID výsledku v databázi Scopus

2-s2.0-85085351653