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Ecological Energetics of Rainbow Smelt in the Laurentian Great Lakes: An Interlake Comparison
Author(s) -
Lantry Brian F.,
Stewart Donald J.
Publication year - 1993
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(1993)122<0951:eeorsi>2.3.co;2
Subject(s) - smelt , predation , energetics , abundance (ecology) , environmental science , ecology , fishery , biology , zoology , fish <actinopterygii>
We developed an energetics model for rainbow smelt Osmerus mordax to quantify its role as a producer and a predator in Great Lakes ecosystems. We measured the weight ( W , g) and temperature ( T °C) dependences of routine metabolism: R (cal·g –1 ·h –1 ) = 0.3646· W –0.216. e 0.036·T . We evaluated seasonal and ontogenetic patterns of rainbow smelt energy density. Seasonal and size‐dependent diet composition was estimated based on an extensive analysis of smelt diets in Lakes Michigan and Ontario and a synthesis of published diet data for all of the Great Lakes. For each lake, we employed lake‐specific temperature regimes, growth rates, mortality rates, and abundance estimates. Model simulations for the average individual rainbow smelt in the various lakes revealed gross food conversion efficiencies (GCE) of 13.8–15.8% averaged over all age‐classes. For the youngest age‐class, GCE was usually close to 20% and two or three times greater than for age‐classes 4 and 5. An empirical estimate of daily ration in Lake Michigan in late August was between 0.017 and 0.037 g food/g smelt, depending on the value assumed for stomach evacuation rate. Our model predicted a ration of about 0.022 g·g –1 for that same period. Total annual rainbow smelt production and predation were about 100 times greater in Lake Erie than in Lake Superior. Biomass‐specific consumption ( C : B ) ratios per age‐class in Lake Michigan were highest for rainbow smelt of ages 0 and 1 (14.64 and 9.00) and lowest for ages 4 and 5 (4.60 and 4.54). Production was concentrated in the first three age‐classes in all the lakes and ages 0 and 1 accounted for about 87% of the total production in Lake Erie. Population GCE was highest in Lake Erie (20.4%) and lowest in Lake Ontario (15.6%). Production: Biomass ( P : B ) ratios varied from 1.54 in Lake Erie to 1.10 in Lake Ontario. The highest P : B ratio for any age‐class was 2.97 for age‐0 rainbow smelt in Lake Erie and the lowest was 0.29 for age‐4 fish in Lake Huron. Simulations indicated that rainbow smelt biomass is concentrated in age‐classes that may be thermally segregated from salmonine predators and that increased mortality of older smelt age‐classes can reduce predation by smelt on other fishes.