Acoustical estimates of fish and zooplankton distribution in the Piaseczno reservoir, Southern Poland

Abstract

Hydroacoustical surveys in the Piaseczno reservoir were performed in May and September 2002 using a Biosonics 101 dual beam echo sounder. They have revealed very scarce fish populations in pelagic waters with twice-higher abundance in autumn (530 fish ha À1 ) as compared with spring (280 fish ha À1 ). Small and very small fish (below 10 cm length) dominated. Apart from fish, Chaoborus larvae were producing acoustical echoes of the TS similar or slightly weaker than that of small fish. Invertebrates formed a thin layer, less than 2 m thick at the border of an anoxic zone, and were changing their depth position between 6 and 16 m, both diurnally and seasonally.

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

“…Since then, the use of the method for assessment and management of fisheries, species identification and acoustic characterization, behavioral and trophic relationships studies have been widely described in literature (Gerlotto, 1993;Paramo et al, 2003;Vehanen et al, 2005). Among the advantages of acoustic methods, we can emphasize the fact that it is a non-invasive method allowing the exploration of large areas in a relatively short period of time with high, spatial and temporal, resolution (Godlewska and Jelonek, 2006). Echo sounding can provide basic information not only on fish stocks and spatial and temporal distribution, but also on zooplankton (eg Chaoborus), which is the main food resource of juvenile fishes and of some adult species (Godlewska and Jelonek, 2006).…”

“…Among the advantages of acoustic methods, we can emphasize the fact that it is a non-invasive method allowing the exploration of large areas in a relatively short period of time with high, spatial and temporal, resolution (Godlewska and Jelonek, 2006). Echo sounding can provide basic information not only on fish stocks and spatial and temporal distribution, but also on zooplankton (eg Chaoborus), which is the main food resource of juvenile fishes and of some adult species (Godlewska and Jelonek, 2006). Another aspect to consider is that the hydroacoustic technique offers the possibility of obtaining simultaneous data on the lake sediments, bathymetry, and coverage of submerged macrophytes (Wheeler, 2005;Winfield et al, 2007a, b).…”

Can poor foraging habitat (an inundated opencast sulphur mine) be attractive to the great crested grebe (Podiceps cristatus)?

“…Hydroacoustic surveys in Piaseczno reservoir have shown very scarce fish populations in the pelagic waters (280 fish ha -1 in spring and 530 fish ha -1 in autumn) (Godlewska and Jelonek 2006). The ichthyofauna consisted of only 7 common species, dominated by roach (Rutilus rutilus) (Amirowicz unpubl.…”

“…data). Small fish (less than 10 cm in length) dominate in Piaseczno reservoir (Godlewska and Jelonek 2006), these being easily caught and handled by the grebes, which are able to catch fish 3-21 cm long (Cramp and Simmons 1977).…”

Do close range measurements affect the target strength (TS) of fish in horizontal beaming hydroacoustics?

“…One of the most relevant advantages is that it is a non-invasive application that covers large areas with high spatial resolution and low manpower requirements (Simmonds and MacLennan, 2005;Godlewska and Jelonek, 2006). In spite of the advantages of hydroacoustic methods, there are some disadvantages that may complicate the acquisition of accurate estimates of fish TS, especially in horizontal applications (with the transducer positioned parallel to the water surface).…”