Manning N.F.,University of Toledo |
Mayer C.M.,University of Toledo |
Bossenbroek J.M.,University of Toledo |
Tyson J.T.,Sandusky Fisheries Research Unit
Journal of Great Lakes Research | Year: 2013
Water clarity is an important environmental variable that may affect fish populations by altering the visual environment. Effects can change feeding ability, as well as alter predation risk. The western basin of Lake Erie provides a valuable model system for studying the effects of transparency because the two main tributaries, the Maumee and Detroit rivers, differ substantially in clarity. We used Generalized Additive Models (GAMs) to quantify the relationship between transparency and the observed abundance and length of age-0 yellow perch (. Perca flavescens) in August, based on surveys from 1986 to 2006. Secchi data from June to August were included in the models that best explained the variation in yellow perch abundance and length. August values for bottom oxygen and bottom temperature also increased model fit for abundance, whereas only bottom temperature improved model fit for length. Our models indicate that transparency was positively related to the August length while abundance of age-0 yellow perch was inversely related to transparency. Highest abundance was observed in areas with the lowest transparency, with peak abundances observed in areas with less than 1. m of Secchi depth. This is in contrast to August length, which increased as transparency increased, to an asymptote at around 3. m of Secchi depth. The split nature of water clarity conditions in the western basin of Lake Erie has resulted in areas with higher growth potential, versus areas with higher apparent survival. © 2013 society.
Feiner Z.S.,Purdue University |
Chong S.C.,Ontario Ministry of Natural Resources |
Knight C.T.,Fairport Fish Research Station |
Lauer T.E.,Ball State University |
And 4 more authors.
Evolutionary Applications | Year: 2015
Size-selective harvest of fish stocks can lead to maturation at smaller sizes and younger ages, which may depress stock productivity and recovery. Such changes in maturation may be very slow to reverse, even following complete fisheries closures. We evaluated temporal trends in maturation of five Great Lakes stocks of yellow perch (Perca flavescens Mitchill) using indices that attempt to disentangle plastic and evolutionary changes in maturation: age at 50% maturity and probabilistic maturation reaction norms (PMRNs). Four populations were fished commercially throughout the time series, while the Lake Michigan fishery was closed following a stock collapse. We documented rapid increases in PMRNs of the Lake Michigan stock coincident with the commercial fishery closure. Saginaw Bay and Lake Huron PMRNs also increased following reduced harvest, while Lake Erie populations were continuously fished and showed little change. The rapid response of maturation may have been enhanced by the short generation time of yellow perch and potential gene flow between northern and southern Lake Michigan, in addition to potential reverse adaptation following the fishing moratorium. These results suggest that some fish stocks may retain the ability to recover from fisheries-induced life history shifts following fishing moratoria. © 2015 The Authors. Evolutionary Applications published by John Wiley & Sons Ltd.
Reichert J.M.,University of Windsor |
Fryer B.J.,University of Windsor |
Pangle K.L.,Ohio State University |
Johnson T.B.,Ontario Ministry of Natural Resources |
And 4 more authors.
Canadian Journal of Fisheries and Aquatic Sciences | Year: 2010
Similar to coastal marine systems, Lake Erie exhibits open-water river plumes that differ physicochemically and biologically from surrounding waters. To explore their importance to yellow perch (Perca flavescens) recruitment in western Lake Erie, we tested two related hypotheses: (0 contributions of larvae to the juvenile stage (when recruitment is set) would be greater from nutrient-rich Maumee River plume (MRP) waters than from less-productive non-MRP waters; and (ii) warmer temperatures and higher zooplankton (prey) production in the MRP (versus non-MRP waters) would underlie this expected recruitment difference through bottom-up effects on larval growth. Peak larval yellow perch density was 10-fold and 5-fold less in the MRP than in non-MRP waters during 2006 and 2007, respectively. However, otolith micro-chemical analyses demonstrated that disproportionately more juvenile recruits emanated from the MRP than from non-MRP waters during both years. Although temperature and zooplankton production were higher in the MRP than in non-MRP waters during both years, observed recruitment differences were not definitively linked to bottom-up effects. Top-down effects also appeared important, as high turbidity in the MRP may offer a survival advantage by reducing predation mortality on larvae. Our research highlights the need to better understand biophysical coupling in freshwater systems and demonstrates how stochastic tributary inputs can influence fish recruitment.
Blaine T.W.,Ohio State University |
Lichtkoppler F.R.,Ohio State University |
Bader T.J.,Fairport Harbor Fisheries Research Unit |
Hartman T.J.,Sandusky Fisheries Research Unit |
Lucente J.E.,Ohio State University
Journal of Environmental Management | Year: 2015
We examine sensitivity of estimates of recreation demand using the Travel Cost Method (TCM) to four factors. Three of the four have been routinely and widely discussed in the TCM literature: a) Poisson verses negative binomial regression; b) application of Englin correction to account for endogenous stratification; c) truncation of the data set to eliminate outliers. A fourth issue we address has not been widely modeled: the potential effect on recreation demand of the interaction between income and travel cost. We provide a straightforward comparison of all four factors, analyzing the impact of each on regression parameters and consumer surplus estimates. Truncation has a modest effect on estimates obtained from the Poisson models but a radical effect on the estimates obtained by way of the negative binomial. Inclusion of an income-travel cost interaction term generally produces a more conservative but not a statistically significantly different estimate of consumer surplus in both Poisson and negative binomial models. It also generates broader confidence intervals. Application of truncation, the Englin correction and the income-travel cost interaction produced the most conservative estimates of consumer surplus and eliminated the statistical difference between the Poisson and the negative binomial. Use of the income-travel cost interaction term reveals that for visitors who face relatively low travel costs, the relationship between income and travel demand is negative, while it is positive for those who face high travel costs. This provides an explanation of the ambiguities on the findings regarding the role of income widely observed in the TCM literature. Our results suggest that policies that reduce access to publicly owned resources inordinately impact local low income recreationists and are contrary to environmental justice. © 2014 Elsevier Ltd.
Pritt J.J.,University of Toledo |
Dufour M.R.,University of Toledo |
Mayer C.M.,University of Toledo |
Kocovsky P.M.,U.S. Geological Survey |
And 3 more authors.
Canadian Journal of Fisheries and Aquatic Sciences | Year: 2013
Walleye (Sander vitreus) in Lake Erie is a valuable and migratory species that spawns in tributaries. We used hydroacoustic sampling, gill net sampling, and Bayesian state-space modeling to estimate the spawning stock abundance, characterize size and sex structure, and explore environmental factors cuing migration of walleye in the Maumee River for 2011 and 2012. We estimated the spawning stock abundance to be between 431 000 and 1 446 000 individuals in 2011 and between 386 400 and 857 200 individuals in 2012 (95% Bayesian credible intervals). A back-calculation from a concurrent larval fish study produced an estimate of 78 000 to 237 000 spawners for 2011. The sex ratio was skewed towards males early in the spawning season but approached 1:1 later, and larger individuals entered the river earlier in the season than smaller individuals. Walleye migration was greater during low river discharge and intermediate temperatures. Our approach to estimating absolute abundance and uncertainty as well as characterization of the spawning stock could improve assessment and management of this species, and our methodology is applicable to other diadromous populations.