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For a copy of the full completion report, please contact the author via
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A coupled physical-biological model
to forecast larval yellow perch distributions, growth rates, and potential
recruitment in Lake Erie
Xia M.1, Pangle K.2, Marin
Jarrin J.R.2, Ludsin S.3, Mason D.4, Rutherford,
E.4, and Wiley, M.5
1University of Maryland Eastern Shore, Dept. of Natural
Sciences, Princess Anne, MD
2Central Michigan University, Dept. of Biology, Mt. Pleasant, MI
3The Ohio State University, Dept. of Evolution, Ecology, and Organismal
Biology, Aquatic Ecology Laboratory, Columbus, OH
4National Oceanic and Atmospheric Administration-GLERL,
Ann Arbor, MI
5University of
Michigan, Ann Arbor, MI
November 2014
ABSTRACT:
Yellow
perch (Perca flavescens; YP) is an economically and ecologically
important species across the Great Lakes, which demonstrates variable
recruitment to the fishery that we hypothesized is regulated by physical processes
operating during early life stages. Previous research has found recruitment
success is positively correlated with Maumee River inflow during spring, with
individuals that use the Maumee River plume (MRP) as larvae contributing disproportionately
to the new year-class. Research also has identified water turbidity as a key
regulator of larval recruitment success because it reduces the ability of
predators to forage on planktivorous fish such as larval YP. However,
uncertainty in predicting the plume dynamics, as well as its effect on
movement, predation risk, consumption, growth, and survival of YP larvae
remains a major impediment to fully understanding and forecasting recruitment
to the fishery in this system. To address these important questions, we built a
coupled biophysical model of western Lake Erie. This model coupled general
linear models developed to accurately predict YP growth and length (r2
= 0.84) with a physical (hydrodynamics and sediment) model that uses a
flexible, unstructured grid to capture current dynamics, even in shallow
nearshore areas. Using the biophysical model, we (a) evaluated the interactive effects of river discharge and wind-driven
currents on the creation and expansion of high-quality nursery habitat within
the MRP, (b) determined the relative importance of advection-caused loss of YP
larvae to the observed disproportionate recruitment of MRP individuals relative
to non-MRP individuals and (c) identified mechanistic linkages between physical
processes and YP year-class strength.
Our analysis
found that the MRP area is most strongly influenced by Maumee River discharge
and wind strength and direction, with larger plumes occurring at high discharge
events when winds were from the E and NE. Other factors such
as the Detroit River discharge and sediment input, local and distant wind
forcing, wave climate and sediment resuspension can also influence MRP dynamics
at a smaller scale. Advection of MRP and non-MRP YP out of the western basin was
unimportant whether larvae exhibited an active swimming behavior or not (mean #
particles lost < 5 %). This retention of larvae in the basin is likely due
to an anticyclonic circulation pattern that is commonly exhibited in the basin
that could help retain larvae. Further model and empirical analysis suggested,
however, that in order to remain in the MRP (i.e., not simply the basin),
larvae are required to exhibit an active swimming behavior. Finally, our
results suggest the mechanisms influencing YP survival are dependent upon
average plume size during the spring and on water temperature during early May.
Year-classes that experienced low water temperature during May of their first
year of life recruited at higher levels (>20 million 2-year olds) and were
positively related to the size of the plume, modeled retention of larvae in the
plume and modeled survival rates. Year-classes that experienced high water
temperatures during May of their first year of life recruited at low levels
(<20 million 2-year olds) regardless of the size of the plume, modeled
retention of larvae in the plume and modeled survival rates. The causes behind
these different relationships may be due to a match-mismatch with prey and
predators, or differences in larval quality between cold and warm early springs.
In conclusion, these results suggest that the size of the MRP, a high quality
habitat for larval YP, is largely determined by wind forcing and river
discharge, and that the size of the plume, in addition to spring water
temperature, can be used to predict the number of these fish that survive to
enter the fishery at age-2. Managers may therefore want to continue updating
our hydrodynamics model with recent years to help forecast future year-classes.