Species Status Assessment (SSA) Report for the Ozark Chub (Erimystax Harryi) Version 1.2
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Species Status Assessment (SSA) Report for the Ozark Chub (Erimystax harryi) Version 1.2 Ozark chub (Photo credit: Dustin Lynch, Arkansas Natural Heritage Commission) August 2019 U.S. Fish and Wildlife Service - Arkansas Ecological Services Field Office This document was prepared by Alyssa Bangs (U. S. Fish and Wildlife Service (USFWS) – Arkansas Ecological Services Field Office), Bryan Simmons (USFWS—Missouri Ecological Services Field Office), and Brian Evans (USFWS –Southeast Regional Office). We greatly appreciate the assistance of Jeff Quinn (Arkansas Game and Fish Commission), Brian Wagner (Arkansas Game and Fish Commission), and Jacob Westhoff (Missouri Department of Conservation) who provided helpful information and review of the draft document. We also thank the peer reviewers, who provided helpful comments. Suggested reference: U.S. Fish and Wildlife Service. 2019. Species status assessment report for the Ozark chub (Erimystax harryi). Version 1.2. August 2019. Atlanta, GA. CONTENTS Chapter 1: Executive Summary 1 1.1 Background 1 1.2 Analytical Framework 1 CHAPTER 2 – Species Information 4 2.1 Taxonomy and Genetics 4 2.2 Species Description 5 2.3 Range 6 Historical Range and Distribution 6 Current Range and Distribution 8 2.4 Life History Habitat 9 Growth and Longevity 9 Reproduction 9 Feeding 10 CHAPTER 3 –Factors Influencing Viability and Current Condition Analysis 12 3.1 Factors Influencing Viability 12 Sedimentation 12 Water Temperature and Flow 14 Impoundments 15 Water Chemistry 16 Habitat Fragmentation 17 3.2 Model 17 Analytical Units 18 Watershed Parameters 18 Population Parameters 20 3.3 Current Condition—3Rs 21 Resiliency 21 Representation 21 Redundancy 22 CHAPTER 4 – Future Condition Analysis/Species Viability 27 4.1 Parameters 27 Urban Cover 27 Riparian Forest Cover 28 Water Quality 28 Abundance 28 4.2 Scenarios 32 Scenario 1 (positive habitat change) 32 Scenario 2 (increased urbanization) 32 Scenario 3 (increased urbanization, other parameters slightly decreased) 32 Scenario 4 (increased urbanization, other parameters decreased) 32 4.3 Summary 33 REFERENCES 34 Appendix A. Ozark Chub Ecological Management Units and Watersheds 41 Upper White River Ecological Management Unit 42 Middle White River Ecological Management Unit 44 Middle Black River Ecological Management Unit 45 St Francis River Ecological Management Unit 47 Little Red River Ecological Management Unit 48 Chapter 1: Executive Summary 1.1 Background This report summarizes the results of a species status assessment (SSA) conducted for the Ozark chub (Erimystax harryi), which includes relevant information about the species’ life history characteristics, how those characteristics are affected by stressors, and conservation measures to address those stressors. The U.S. Fish and Wildlife Service (Service) was petitioned to list 404 aquatic, riparian, and wetland species, including the Ozark chub, as endangered or threatened under the Endangered Species Act of 1973, as amended (Act) on April 20, 2010, by the Center for Biological Diversity (Center for Biological Diversity 2010, p. 417-418). In September of 2011, the Service found the petition presented substantial scientific or commercial information indicating that listing 374 species, including Ozark chub, may be warranted. Thus, we conducted a SSA to compile the best scientific and commercial data available regarding the species biology and factors influencing species viability. 1.2 Analytical Framework The SSA framework (USFWS 2016) is intended to be an in-depth review of the species’ biology and threats, an evaluation of its biological status, and an assessment of the resources and conditions needed to maintain long-term viability. The intent is for the SSA report to be easily updated as new information becomes available and to support all functions of the Endangered Species Program from candidate assessment to listing to consultations and recovery. As such, the SSA report will be a living document used to inform decisions under the ESA. The Ozark chub SSA is intended to provide the biological support for the decision on whether to propose listing the species as threatened or endangered and, if so, to determine whether it is prudent to designate critical habitat areas essential to its conservation. This report is not a decisional document by the Service; rather, it provides a review of available information strictly related to the biological status of Ozark chub. A listing decision will be made by the Service after reviewing this document and all relevant laws, regulations, and policies. The results of a proposed decision will be announced in the Federal Register with appropriate opportunities for public input. Using the SSA framework (Figure 1), we consider what the species needs to maintain viability (the species’ ability to sustain populations in the wild over time) by characterizing the status of the species in terms of its redundancy, representation, and resiliency (USFWS 2016, entire; Wolf et al. 2015, entire). For the purpose of this assessment, we generally define viability as the ability of the species to sustain populations in natural stream ecosystems within a biologically meaningful timeframe. Resiliency, redundancy, and representation are defined as follows: ● Resiliency is assessed at the population level and reflects a species’ ability to withstand stochastic events (arising from random factors). Demographic measures that reflect population health, such as fecundity, survival, and population size, are the metrics used to evaluate resiliency. Resilient populations are better able to withstand disturbances such as random fluctuations in birth rates (demographic stochasticity), variations in rainfall (environmental stochasticity), and the effects of anthropogenic activities. ● Representation is assessed at the species’ level and characterizes the ability of a species to adapt to changing environmental conditions. Metrics such as a species’ adaptive potential and genetic and ecological variability can be used to assess representation. Representation is directly correlated to a species’ ability to adapt to changes (natural or human-caused) in its environment. In the absence of species-specific genetic and ecological diversity information, we evaluate representation based on the extent and variability of habitat characteristics within the geographical range. ● Redundancy is also assessed at the species level and reflects a species’ ability to withstand catastrophic events (such as a rare destructive natural event or episode involving many populations) by having a sufficient number of populations. Redundancy is about spreading the risk of such an event across multiple, resilient populations. As such, redundancy can be measured by the number and distribution of resilient populations across the range of the species. The decision whether to list a species is based not on a prediction of the most likely future for the species, but rather on an assessment of the species’ risk of extinction. Therefore, to inform this assessment of extinction risk, we describe the species’ current biological status and assess how this status may change in the future under a range of scenarios to account for the uncertainty of the species’ future. We evaluate the current biological status of Ozark chub by assessing the primary factors negatively and positively affecting the species to describe its current condition in terms of resiliency, redundancy, and representation (together, the 3Rs). We then evaluate the future biological status of Ozark chub by describing a range of plausible future scenarios representing a range of conditions for the primary factors affecting the species and forecasting the most likely future condition for each scenario in terms of the 3Rs. As a matter of practicality, the full range of potential future scenarios and range of potential future conditions for each potential scenario are too large to individually describe and analyze. These scenarios do not include all possible futures, but rather include specific plausible scenarios that represent examples from the continuous spectrum of possible futures. Consequently, the results of this SSA do not describe the overall risk to the species. Recognizing these limitations, the results of this SSA nevertheless provide a framework for considering the overall risk to the species in listing decisions. This report includes: a description of Ozark chub resource needs at both individual and population levels (Chapter 1); a characterization of the historical and current distribution of populations across the species’ range (Chapter 2); an assessment of factors that contributed to the current and future status of the species and degree to which various factors influenced viability (Chapter 3); and a synopsis of factors characterized in earlier chapters as a means of examining future biological status of the species (Chapter 4). This document is a compilation of the best available scientific information (and associated uncertainties regarding that information) used to assess Ozark chub viability. CHAPTER 2 – Species Information 2.1 Taxonomy and Genetics Ozark chub (Erimystax harryi) belongs to the Cyprinidae family of fishes. It is currently recognized as a valid taxon by the American Fisheries Society (Page et al. 2013, p. 70) and is listed as such in the Integrated Taxonomic Information System (ITIS) database (http://www.itis.gov). The currently accepted classification is (ITIS 2018): Phylum: Chordata Class: Teleostei Order: Cypriniformes Family: