Improved trawling setup for sampling pelagic juvenile fish communities in small inland bodies of water

Jůza, Tomáš; Sajdlová, Zuzana; Čech, Martin; Draštík, Vladislav; Kočvara, Luboš; Tušer, Michal; Kubečka, Jan

doi:10.3750/aiep/02373

Cited by 4 publications

(2 citation statements)

References 5 publications

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“…This smaller trawl was used to avoid directly contacting the bottom because of the risk of destroying the trawl. Both trawls were held at the correct depth by a rope of appropriate length between the trawl frame and the flat-bottomed boat, which served as a float and to release the catch from the trawl (Ju ˚za et al, 2018).…”

Section: Pelagic Trawlingmentioning

confidence: 99%

Spatial fish distribution in autumn in a shallow mesotrophic lake, assessed by hydroacoustic surveys, trawling, and beach seining

Jůza,

Muška,

Blabolil

et al. 2024

Journal of Fish Biology

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Day and nighttime autumn fish abundance and biomass were studied in the pelagic and littoral zones of Lake Sauka in Latvia. Both pelagic methods (hydroacoustics and trawling) revealed significantly higher fish abundance and biomass during the day than at night, especially in deeper zones (below 3 m). Roach (Rutilus rutilus) and Eurasian perch (Perca fluviatilis) dominated the trawl catches during the day, while roach and ruffe dominated at night. Fish smaller than 14 cm strongly dominated in both the trawl catches and hydroacoustic observations. Our hydroacoustic sampling found inhomogeneous pelagic distributions of fish aggregated in big shoals during the day. In the littoral zone, which was sampled by beach seining, both the abundance and biomass were significantly higher at night than during the day. Roach, bleak, and European perch usually dominated in beach seine catches during the day and at night. The daytime pelagic biomass found by hydroacoustics was 62 kg/ha and it decreased to approximately 11 kg/ha at night. The littoral biomass found by beach seining was diurnally opposite, 4 kg/ha during the day and 37 kg/ha at night. It is obvious that diurnal horizontal migrations between pelagic and littoral zones, and shoaling behavior during the daytime are common patterns in the shallow Lake Sauka during the autumn. The study of the spatial distribution of fish is extremely important for the establishment of an appropriate monitoring plan for the purposes of the Water Framework Directive with regard to the morphometry of the lake, the geographical location, and the sampling period of the year. This study also shows that the combination of completely non‐invasive hydroacoustic and other methods that are invasive (trawls, beach seines) but not as destructive as gillnets, which are normally used for scientific fish monitoring in Europe, could be a future way forward for fish monitoring.

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Section: Pelagic Trawlingmentioning

confidence: 99%

Spatial fish distribution in autumn in a shallow mesotrophic lake, assessed by hydroacoustic surveys, trawling, and beach seining

Jůza,

Muška,

Blabolil

et al. 2024

Journal of Fish Biology

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“…Su et al [13] focused on the warp length of a trawling system. Juza et al [14] introduced a two-boat setup for continuous trawling for quicker and more convenient trawling, even in deep water layers; this setup helps achieve more accurate distance and depth measurements. Park and Lee [15] adjusted the trawler direction and warp length during trawling for the automatic control of the trawler gear depth.…”

Section: Introductionmentioning

confidence: 99%

Study on the Dynamic Response of Deep-Sea Trawlers in Sea Trials

Xie

Cai

et al. 2023

Polish Maritime Research

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The increasing use of automation in fishing vessels has improved trawling efficiency while directly affecting the fishing capacity and cost of fishing vessels. Among the various influencing factors, warp tension and warp length can be varied to automatically balance the retraction and release of warp control. We combined the two parameters and independently designed and developed the key equipment for fishing vessels—the warp dynamometer and meter counter—and control software. The accuracy of the warp tension and length measurements was improved. The designed equipment was applied to sea trials under different working conditions, and the test data records were exported. Next, filtered time-domain graphs of the required parameters were plotted through complex Fourier transform, first-order low-pass filtering, and inverse Fourier transform. The results of data processing using various parameters were compared and analysed to determine the variation trends of the parameters and verify the effects of their balance control. The results indicated that using an automatic balance control system that combines warp tension and warp length can be effective for the fishing operation of offshore double-deck trawlers. In addition, first-order low-pass filtering can be used to filter complex warp tension data. This study also determined the relationship between warp tension and experimental parameters such as warp length and ship speed during the release of control. After the balance control of warp tension and warp length, the net mouth area increased by 30.7% and 36.5%, respectively, and the fishing efficiency of the vessel improved considerably.

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The impact of climatic conditions and food availability on bimodality size structure and density of YOY pikeperch (Sander lucioperca)

Tesfaye,

Jůza,

Šmejkal

et al. 2024

Hydrobiologia

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Improved trawling setup for sampling pelagic juvenile fish communities in small inland bodies of water

Cited by 4 publications

References 5 publications

Spatial fish distribution in autumn in a shallow mesotrophic lake, assessed by hydroacoustic surveys, trawling, and beach seining

Spatial fish distribution in autumn in a shallow mesotrophic lake, assessed by hydroacoustic surveys, trawling, and beach seining

Study on the Dynamic Response of Deep-Sea Trawlers in Sea Trials

The impact of climatic conditions and food availability on bimodality size structure and density of YOY pikeperch (Sander lucioperca)

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