Implementation of hydroacoustic for a rapid assessment of fish spatial distribution at a Brazilian Lake - Lagoa Santa, MG

Abstract

Aim: To study the distribution, structure, size and density of fish in the karst lake: Lagoa Central (Lagoa Santa, MG -surface area: 1.7 km 2 ; mean depth: 4.0 m; and maximum depth: 7.3 m). Methods: The hydroacoustic method with vertical beaming was applied, using the echosounder Biosonics DT-X with a split-beam transducer of 200 kHz. The analysis of the acoustic data was performed with the software Visual Analyzer (Biosonics Inc.). Thematic maps of density echoes associated with fish, estimated by the technique of echo-integration, were made using the kriging interpolation. The density and vertical distribution of insonified fish were estimated using the technique of echo-counting. Results: The lake had a mean density of 0.89 echoes associated with fish per m 2 , showing large spatial variations in the density of fish. The size estimated for the echoes associated with fish range from 2.7 to 15.9 cm (mean = 5.3 cm). Conclusions: The use of hydroacoustic to obtain rapid and realistic estimates of fish abundance and vertical distribution of the fish stock was successful.Keywords: ichthyofauna, density, fisheries, Lagoa Santa.Resumo: Objetivos: Estudar a distribuição, densidade e estrutura de tamanho de peixes nas águas da Lagoa Central (Lagoa Santa, MG -área: 1,7 km 2 ; profundidade média: 4,0 m; e profundidade máxima: 7,3 m). Métodos: O estudo utilizou o método hidroacústico com orientação vertical. Uma sonda Biosonics DT-X, equipada com um transdutor split-beam de 200 kHz, foi utilizada. A análise dos dados acústicos foi feita com o programa Visual Analyser (Biosonics Inc.). Mapas temáticos de densidades dos ecos associados a peixes, estimadas através da técnica de eco-integração, foram confeccionados utilizando a interpolação kriging. Já o número e distribuição vertical dos peixes insonificados foram determinados utilizando a técnica de eco-contagem. Resultados: A Lagoa Central apresentou uma densidade média de 0,89 ecos associados a peixes por m 2 , indicando grandes variações na densidade dos peixes em áreas particulares do lago. A estimativa de tamanho dos ecos associados a peixes variou de 2,7 a 15,9 cm (média = 5,3 cm). Conclusões: O uso de hidroacústica para obter estimativas rápidas e realistas de abundância de peixes e distribuição vertical da população de peixes foi bem sucedida.Palavras-chave: ictiofauna, densidade, recurso pesqueiro, Lagoa Santa.

Using the hydroacoustic and mini trawl data for estimating fish density in the eastern part of Banyuasin coastal waters, South Sumatra of Indonesia

“…These coastal zones near the mangrove area are useful nursery, feeding and spawning grounds (Walters et al 2008;Eddy et al 2016), consequently these waters favoured the fishes and resulted in a higher fish abundance and density. This distribution pattern was in line with the hydroacoustic survey at a Brazilian Lake -Lagoa Santa, Minas Gerais (Bezerra-Neto et al 2013).…”

“…The estimation of fish density using the traditional methods (traps and nets) requires a great effort, financial resources, and time, therefore the recent hydroacoustic development is an essential alternative to these traditional methods (Ehrenberg and Steig 2003;Chen et al 2009;Bezerra-Neto et al 2013). When a substantial hydroacoustic development was introduced in the 1970s, especially the echo-integration technique (Bezerra-Neto et al 2013), hydroacoustic methods and technology are being increasingly and extensively applied as a tool to describe aquatic ecosystems as well as estimating fish density, biomass, and abundance in both freshwaters and marine system (Boswell et al 2007;Rudstam et al 2009;Trenkel et al 2011). Hydroacoustic is also used for estimating zooplankton (Greenlaw 1979;Holliday et al 1989;Martin et al 1996;Miyashita and Aoki 1999;Holbrook et al 2006;Kim et al 2019) and identifying the bottom substrate type (Costa et al 2013;Fauziyah et al 2018aFauziyah et al , 2020aMontereale-Gavazzi et al 2018).…”

Hydroacoustics as a relevant tool to monitor fish dynamics in large estuaries

“…Hydroacoustics has the advantage of being easily adaptable. Thanks to portable equipment, it can be carried out in small boats with a limited crew (Bezerra-Neto et al, 2013). Combined surveys may offer extended complementary information by balancing their particular drawbacks (Emmrich et al, 2010).…”

Support capacity of a floodplain lake for intensive fish production (Rondônia, Brazil)

“…Bathymetric characterization, when evaluated concomitantly with limnological studies, provides important information about the environmental characteristics of a lake ecosystem, and can assist in making decisions regarding the sustainable use of lakes and in the vertical estimation of fish populations (Bezerra-Neto et al, 2013), in the management of fish stocks (Silva-Junior et al, 2017), in the implementation of aquaculture projects (Mendes and Carvalho, 2016) and in the evaluation of the impacts caused by the ichthyofauna (Attayde et al, 2011).…”