Publication Date:
2021-05-19
Description:
To determine the best acoustic sampling period for obtaining fish biomass estimates of a Mediterranean deep reservoir in Tunisia, we carried out day and night surveys in each of four seasons [spring (April), summer (September), autumn (December) and winter (March)]. A Simrad EK60 echosounder, equipped with two 120 kHz split-beam transducers for simultaneous horizontal and vertical beaming, was used to sample the entire water column. Data collected in December were not usable because fish merged with methane gas bubbles. However, fish abundance varied across the other seasons with a peak in acoustic biomass observed during summer nighttime hours that was associated with high water temperatures. Across seasons, the fish occupied the entire water column, and fish schools were rarely observed. The preferential timeframe (i.e. maximum fish detectability and low gas flux) for acoustic sampling was nighttime hours in summer and daytime hours during spring and winter. Our findings highlight the importance of collecting data across seasons and photoperiods when determining an acoustic sampling strategy.
Description:
This is the pre-peer reviewed version of the following article: [Djemali I., Laouar H. Acoustic fish biomass assessment in a deep Tunisian reservoir: effects of season and diel rhythm on survey results. in: African Journal of Aquatic Science. 2017. IN PRESS], which has been published in final form at [https://doi.org/10.2989/16085914.2016.1277181]. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.
Description:
In Press
Keywords:
Target strength.
;
Fisheries.
;
Photoperiod.
;
Gas bubbles
;
Artificial lake
;
Acoustics
Repository Name:
AquaDocs
Type:
Journal Contribution
,
Refereed
Format:
pp.35-43
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