Hydroacoustic estimates of abundance and spatial distribution of pelagic prey fishes in western Lake Superior

Journal of Great Lakes Research
By: , and 

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Abstract

Lake herring (Coregonus artedi) and rainbow smelt (Osmerus mordax) are a valuable prey resource for the recovering lake trout (Salvelinus namaycush) in Lake Superior. However, prey biomass may be insufficient to support the current predator demand. In August 1997, we assessed the abundance and spatial distribution of pelagic coregonines and rainbow smelt in western Lake Superior by combining a 120 kHz split beam acoustics system with midwater trawls. Coregonines comprised the majority of the midwater trawl catches and the length distributions for trawl caught fish coincided with estimated sizes of acoustic targets. Overall mean pelagic prey fish biomass was 15.56 kg ha−1 with the greatest fish biomass occurring in the Apostle Islands region (27.98 kg ha−1), followed by the Duluth Minnesota region (20.22 kg ha−1), and with the lowest biomass occurring in the open waters of western Lake Superior (9.46 kg ha−1). Biomass estimates from hydroacoustics were typically 2–134 times greater than estimates derived from spring bottom trawl surveys. Prey fish biomass for Lake Superior is about order of magnitude less than acoustic estimates for Lakes Michigan and Ontario. Discrepancies observed between bioenergetics-based estimates of predator consumption of coregonines and earlier coregonine biomass estimates may be accounted for by our hydroacoustic estimates.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Hydroacoustic estimates of abundance and spatial distribution of pelagic prey fishes in western Lake Superior
Series title Journal of Great Lakes Research
DOI 10.1016/S0380-1330(05)70274-4
Volume 31
Issue 4
Year Published 2005
Language English
Publisher Elsevier
Contributing office(s) Great Lakes Science Center
Description 13 p.
First page 426
Last page 438
Online Only (Y/N) N
Additional Online Files (Y/N) N