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Old Lyme, CT, United States

Hessenauer J.-M.,University of Connecticut | Vokoun J.C.,University of Connecticut | Suski C.D.,University of Illinois at Urbana - Champaign | Davis J.,Inland Fisheries Division | And 2 more authors.
PLoS ONE | Year: 2015

Non-random mortality associated with commercial and recreational fisheries have the potential to cause evolutionary changes in fish populations. Inland recreational fisheries offer unique opportunities for the study of fisheries induced evolution due to the ability to replicate study systems, limited gene flow among populations, and the existence of unexploited reference populations. Experimental research has demonstrated that angling vulnerability is heritable in Largemouth Bass Micropterus salmoides, and is correlated with elevated resting metabolic rates (RMR) and higher fitness. However, whether such differences are present in wild populations is unclear. This study sought to quantify differences in RMR among replicated exploited and unexploited populations of Largemouth Bass. We collected age-0 Largemouth Bass from two Connecticut drinking water reservoirs unexploited by anglers for almost a century, and two exploited lakes, then transported and reared them in the same pond. Field RMR of individuals from each population was quantified using intermittent-flow respirometry. Individuals from unexploited reservoirs had a significantly higher mean RMR (6%) than individuals from exploited populations. These findings are consistent with expectations derived from artificial selection by angling on Largemouth Bass, suggesting that recreational angling may act as an evolutionary force influencing the metabolic rates of fishes in the wild. Reduced RMR as a result of fisheries induced evolution may have ecosystem level effects on energy demand, and be common in exploited recreational populations globally. © 2015 Hessenauer et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Source

Palkovacs E.P.,University of California at Santa Cruz | Hasselman D.J.,University of California at Santa Cruz | Argo E.E.,University of California at Santa Cruz | Gephard S.R.,Inland Fisheries Division | And 4 more authors.
Evolutionary Applications | Year: 2014

A major challenge in conservation biology is the need to broadly prioritize conservation efforts when demographic data are limited. One method to address this challenge is to use population genetic data to define groups of populations linked by migration and then use demographic information from monitored populations to draw inferences about the status of unmonitored populations within those groups. We applied this method to anadromous alewife (Alosa pseudoharengus) and blueback herring (Alosa aestivalis), species for which long-term demographic data are limited. Recent decades have seen dramatic declines in these species, which are an important ecological component of coastal ecosystems and once represented an important fishery resource. Results show that most populations comprise genetically distinguishable units, which are nested geographically within genetically distinct clusters or stocks. We identified three distinct stocks in alewife and four stocks in blueback herring. Analysis of available time series data for spawning adult abundance and body size indicate declines across the US ranges of both species, with the most severe declines having occurred for populations belonging to the Southern New England and the Mid-Atlantic Stocks. While all alewife and blueback herring populations deserve conservation attention, those belonging to these genetic stocks warrant the highest conservation prioritization. © 2013 The Authors. Evolutionary Applications published by John Wiley & Sons Ltd. Source

Ruzzante D.E.,Dalhousie University | McCracken G.R.,Dalhousie University | Parmelee S.,Dalhousie University | Hill K.,Dalhousie University | And 3 more authors.
Proceedings of the Royal Society B: Biological Sciences | Year: 2016

The relationship between the effective number of breeders (Nb) and the generational effective size (Ne) has rarely been examined empirically in species with overlapping generations and iteroparity. Based on a suite of 11 microsatellite markers, we examine the relationship between Nb, Ne and census population size (Nc) in 14 brook trout (Salvelinus fontinalis) populations inhabiting 12 small streams in Nova Scotia and sampled at least twice between 2009 and 2015. Unbiased estimates of Nb obtained with individuals of a single cohort, adjusted on the basis of age at first maturation (a) and adult lifespan (AL), were from 1.66 to 0.24 times the average estimates of Ne obtained with random samples of individuals of mixed ages (i.e. Nb(adj2)=mean (Ne(mixed ages))). In turn, these differences led to adjusted Ne estimates that were from nearly five to 0.7 times the estimates derived from mixed-aged individuals. These differences translate into the same range of variation in the ratio of effective to census population size (Ne(adj2)= Nc) within populations. Adopting Ne(adj2) as the more precise and unbiased estimates, we found that these brook trout populations differ markedly in their effective to census population sizes (range approX.0.3 to approX.0.01). Using AGENE, we then showed that the variance in reproductive success or reproductive skew varied among populations by a factor of 40, from Vk/k ≈ 5 to 200. These results suggest wide differences in population dynamics, probably resulting from differences in productivity affecting the intensity of competition for access to mates or redds, and thus reproductive skew. Understanding the relationship between Ne, Nb and Nc, and how these relate to population dynamics and fluctuations in population size, are important for the design of robust conservation strategies in small populations with overlapping generations and iteroparity. © 2016 The Author(s) Published by the Royal Society. All rights reserved. Source

Hessenauer J.-M.,University of Connecticut | Vokoun J.,University of Connecticut | Davis J.,Inland Fisheries Division | Jacobs R.,Inland Fisheries Division | Odonnell E.,Inland Fisheries Division
Journal of Freshwater Ecology | Year: 2014

Recreational fishing can alter the demography and life history characteristics of fish populations. Unexploited populations are useful references for fisheries managers to place into context the extent of changes in exploited populations and the outcomes of management actions. Our objective is to characterize the largemouth bass Micropterus salmoides populations in two unexploited reservoirs in Connecticut and compare them with an exploited reservoir. Unexploited Hemlock Reservoir was characterized by large proportions of large fish in good condition with relatively low population mortality rates. Unexploited Easton Reservoir's bass proportional size distributions were more similar to exploited Mansfield Hollow Reservoir bass population. However, both unexploited reservoirs had higher catch per effort of stock-size and greater fish than Mansfield Hollow Reservoir indicating greater overall density of large fish. The study of long-term unexploited populations may become more important in the future as managers consider the evolutionary consequences of recreational exploitation. © 2014 Taylor & Francis. Source

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