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In Situ Target Strength of Alewives in Freshwater
Author(s) -
Warner David M.,
Rudstam Lars G.,
Klumb Robert A.
Publication year - 2002
Publication title -
transactions of the american fisheries society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.696
H-Index - 86
eISSN - 1548-8659
pISSN - 0002-8487
DOI - 10.1577/1548-8659(2002)131<0212:istsoa>2.0.co;2
Subject(s) - smelt , alewife , fish <actinopterygii> , pelagic zone , biology , coregonus , fishery , target strength , abundance (ecology) , zoology
Abstract Acoustic estimation of absolute fish abundance depends on knowledge of the relationship between target strength (TS) and size for the species of interest. We have derived a relationship between in situ TS and both length ( L , cm) and mass ( W , g) for alewives Alosa pseudoharengus in Lake Ontario and eight inland lakes in New York to provide equations for predicting one variable from the other. The pelagic fish community in these lakes was dominated by alewives (≥80% numerically). Target strength distributions from fish populations investigated in 25 surveys were multimodal, whereas those for individual fish were unimodal, indicating that each mode for the populations corresponded to a size‐group of alewives (range, 2.5‐15.2 cm). The positive relationship between mean TS and mean length was highly significant (TS = 20.53 log 10 L − 64.25), as was the relationship between mean TS and mean mass (TS = 6.98 log 10 W − 50.07). These equations are similar to one often‐used TS‐length relationship but differ substantially from other relationships in the literature. Predictions of TS from our equations were 8.2 decibels greater than those from commonly used equations for marine clupeids. Our equations also differ for fish smaller than 10 cm compared with the equations available for mixed species of Great Lakes forage fish (alewives, rainbow smelt Osmerus mordax , and bloater Coregonus hoyi ).