Comparison of vertical mobile hydroacoustic survey strategies for monitoring fish distributions in the Gironde estuary (France)

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

“…By combining biological information with the results of acoustic surveys at the same temporal and spatial scales, it is possible to obtain reliable data on the distribution and organization of large estuarine fish communities. Building on previous recommendations made by Samedy et al (2013) this study also brought up a range of technical and methodological issues relating to sampling methods and estuarine fish dynamics. Firstly, while hydroacoustics is effective in estimating biomass and fish size, we still used ABC and TS metrics as density and size proxies, in order to avoid any uncertainty stemming from conversion methods to fish weight or fish length (Rose et al, 2000;Godlewska et al, 2009).…”

“…around high tide (to obtain the greatest range of depths), during daylight, and against the current. This approach enabled us to sample a greater volume of water (Samedy et al, 2013). The equipment used was a Simrad EK60 split-beam echosounder controlled by the Simrad ER60 software (version 2.2.0).…”

“…The sampling scheme was based on a mobile strategy with a zigzag design (Simmonds and MacLennan, 2005;Samedy et al, 2013) from one shore of the estuary to the other (Fig. 1).…”

“…In our study, which aimed to create an alternative way of describing spatio-temporal fish distribution, acoustic surveys were conducted in the mesohaline part of the Gironde estuary between 2010 and 2012. Initial methodological analyses (Samedy et al, 2013) showed that mobile vertical acoustic sampling was effective in providing a comprehensive picture of fish dynamics in relation to environmental changes.…”

Using Hydroacoustics to Describe Pelagic Fish Distribution in the Penobscot Estuary, Maine

“…The constantly changing physical conditions in estuaries require robust approaches to fisheries monitoring. Active acoustics using scientific split-beam echo sounders can address some of these challenges and are increasingly being used to monitor fish distributions in estuaries (Boswell et al 2007;Samedy et al 2013). The application of mobile echo sounders in estuaries can provide information on pelagic fish distribution, density, and size over relatively large spatial scales (Stables et al 2005;Goodbrand et al 2013) and are particularly useful where fisheries data are sparse (Horne 2005).…”