Endangered and Threatened Wildlife and Plants; Endangered Species Status for the Alabama Hickorynut and Threatened Status With Section 4(d) Rule for Obovaria cf. unicolor

SUPPLEMENTARY INFORMATION:

Executive Summary

Why we need to publish a rule. Under the Act (16 U.S.C. 1531 et seq.), a species warrants listing if it meets the definition of an endangered (in danger of extinction throughout all or a significant portion of its range) or a threatened species (likely to become an endangered species within the foreseeable future throughout all or a significant portion of its range). If we determine that a species warrants listing, we must list the species promptly and designate the species' critical habitat to the maximum extent prudent and determinable. We have determined that the Alabama hickorynut meets the Act's definition of an endangered species and that Obovaria cf. unicolor meets the Act's definition of a threatened species; therefore, we are proposing to list them accordingly. Listing a species as an endangered species or a threatened species can be completed only by issuing a rule through the Administrative Procedure Act rulemaking process (5 U.S.C. 551 et seq.).

What this document does. We propose to list the Alabama hickorynut as an endangered species, and we propose to list Obovaria cf. unicolor as a threatened species with a rule issued under section 4(d) of the Act (a “4(d) rule”).

The basis for our action. Under the Act, we may determine that a species is an endangered or threatened species because of any of five factors: (A) The present or threatened destruction, modification, or curtailment of its habitat or range; (B) overutilization for commercial, recreational, scientific, or educational purposes; (C) disease or predation; (D) the inadequacy of existing regulatory mechanisms; or (E) other natural or manmade factors affecting its continued existence. We have determined that the Alabama hickorynut is endangered due to the following threats: sedimentation, altered flow regimes, point and nonpoint source pollution, climate change, direct and indirect impacts of development and anthropogenic disturbances, and sea level rise associated with climate change. We have further determined that Obovaria cf. unicolor is threatened due to the following threats: sedimentation, altered flow regimes, point and nonpoint source pollution, climate change, direct and indirect impacts of development and anthropogenic disturbances, and sea level rise associated with climate change.

Information Requested

We intend that any final action resulting from this proposed rule will be based on the best scientific and commercial data available and be as accurate and as effective as possible. Therefore, we request comments or information from other governmental agencies, Native American Tribes, the scientific community, industry, or any other interested parties concerning this proposed rule. We particularly seek comments concerning:

(1) The species' biology, range, and population trends, including:

(a) Biological or ecological requirements of the species, including habitat requirements for feeding, breeding, and sheltering;

(b) Genetics and taxonomy;

(c) Historical and current range, including distribution patterns and the locations of any additional populations of these species;

(d) Historical and current population levels, and current and projected trends; and

(e) Past and ongoing conservation measures for these species, their habitats, or both.

(2) Threats and conservation actions affecting these species, including:

(a) Factors that may be affecting the continued existence of these species, which may include habitat modification or destruction, overutilization, disease, predation, the inadequacy of existing regulatory mechanisms, or other natural or manmade factors;

(b) Biological, commercial trade, or other relevant data concerning any threats (or lack thereof) to these species; and

(c) Existing regulations or conservation actions that may be addressing threats to these species.

(3) Additional information concerning the historical and current status of these species.

(4) Information to assist with applying or issuing protective regulations under section 4(d) of the Act that may be necessary and advisable to provide for the conservation of the Obovaria cf. unicolor. In particular, we seek information concerning:

(a) The extent to which we should include any of the Act's section 9 prohibitions in the 4(d) rule; and

(b) Whether we should consider any additional or different exceptions from the prohibitions in the 4(d) rule.

Please include sufficient information with your submission (such as scientific journal articles or other publications) to allow us to verify any scientific or commercial information you include.

Please note that submissions merely stating support for, or opposition to, the action under consideration without providing supporting information, although noted, do not provide substantial information necessary to support a determination. Section 4(b)(1)(A) of the Act directs that determinations as to whether any species is an endangered or a threatened species must be made solely on the basis of the best scientific and commercial data available.

You may submit your comments and materials concerning this proposed rule by one of the methods listed in ADDRESSES . We request that you send comments only by the methods described in ADDRESSES .

If you submit information via https://www.regulations.gov, your entire submission—including any personal identifying information—will be posted on the website. If your submission is made via a hardcopy that includes personal identifying information, you may request at the top of your document that we withhold this information from public review. However, we cannot guarantee that we will be able to do so. We will post all hardcopy submissions on https://www.regulations.gov.

Comments and materials we receive, as well as supporting documentation we used in preparing this proposed rule, will be available for public inspection on https://www.regulations.gov.

Our final determinations may differ from this proposal because we will consider all comments we receive during the comment period as well as any information that may become available after this proposal. Based on the new information we receive (and, if relevant, any comments on that new information), we may conclude that one or both species are a different status, or we may conclude that one or both species do not warrant listing as either an endangered species or a threatened species. In addition, for Obovaria cf. unicolor, we may change the parameters of the prohibitions or the exceptions to those prohibitions in the protective regulations under section 4(d) of the Act if we conclude it is appropriate in light of comments and new information received. For example, we may expand the prohibitions if we conclude that the protective regulation as a whole, including those additional prohibitions, is necessary and advisable to provide for the conservation of the species. Conversely, we may establish additional or different exceptions to the prohibitions in the final rule if we conclude that the activities would facilitate or are compatible with the conservation and recovery of the species. In our final rule, we will clearly explain our rationale and the basis for our final decisions, including why we made changes, if any, that differ from this proposal.

Public Hearing

Section 4(b)(5) of the Act provides for a public hearing on this proposal, if requested. Requests must be received by the date specified in DATES . Such requests must be sent to the address shown in FOR FURTHER INFORMATION CONTACT . We will schedule a public hearing on this proposal, if requested, and announce the date, time, and place of the hearing, as well as how to obtain reasonable accommodations, in the Federal Register and local newspapers at least 15 days before the hearing. We may hold the public hearing in person or virtually via webinar. We will announce any public hearing on our website, in addition to in the Federal Register . The use of virtual public hearings is consistent with our regulations at 50 CFR 424.16(c)(3).

Previous Federal Actions

In April 2010, the Alabama hickorynut was included in a petition from the Center for Biological Diversity and others (CBD 2010, entire) requesting that the Service list 404 aquatic, riparian, and wetland species as endangered or threatened species under the Act. In response to the petition, on September 27, 2011, the Service published in the Federal Register (76 FR 59836) a partial 90-day finding in which we announced our finding that the petition contained substantial information indicating that listing may be warranted for numerous species, including the Alabama hickorynut.

On February 27, 2020, the Center for Biological Diversity filed a lawsuit against the Service, alleging, among other claims, that the Service violated the Act (16 U.S.C. 1533(b)(3)(B)) by delaying the 12-month finding for the listing of the Alabama hickorynut. The parties entered a settlement agreement on July 24, 2023, in which the Service committed to submit the 12-month finding to the Federal Register by September 2, 2024. This document complies with the settlement agreement.

We note that the April 2010 petition specified an accepted range for the Alabama hickorynut of the eastern Gulf Coast drainages of the Mobile River Basin, the Pascagoula River drainage, the Pearl River drainage, and the Lake Pontchartrain drainages. However, as discussed below under I. Proposed Listing Determination, Background, preliminary data support that Alabama hickorynut ( Obovaria unicolor) is found only in the Mobile River Basin, and the individuals from the other three drainages are a distinct species still undescribed, Obovaria cf. unicolor. Because the Alabama hickorynut was petitioned with the accepted range including all four drainages and because the genetic analysis distinguishing two distinct species is still unpublished, we evaluated the Alabama hickorynut and the undescribed species throughout the entire accepted petitioned range.

Peer Review

A species status assessment (SSA) team prepared an SSA report for Alabama hickorynut, including the undescribed Obovaria cf. unicolor. The SSA team was composed of Service biologists, in consultation with other species experts. The SSA report represents a compilation of the best scientific and commercial data available concerning the status of the species, including the impacts of past, present, and future factors (both negative and beneficial) affecting the species.

In accordance with our joint policy on peer review published in the Federal Register on July 1, 1994 (59 FR 34270), and our August 22, 2016, memorandum updating and clarifying the role of peer review in listing and recovery actions under the Act, we solicited independent scientific review of the information contained in the SSA report for the Alabama hickorynut and Obovaria cf. unicolor. We sent the SSA report to five independent peer reviewers and received no responses.

I. Proposed Listing Determination

Background

The SSA report (Service 2023, pp. 9-16) presents a thorough review of the taxonomy, life history, and ecology of the Alabama hickorynut ( Obovaria unicolor) and Obovaria cf. unicolor.

Species taxonomic status remains unclear for the Alabama hickorynut. Genetics data support Alabama hickorynut ( Obovaria unicolor) as a Mobile River Basin endemic and the individuals of the western drainages (Pascagoula, Pearl, and Pontchartrain) comprising a distinct species yet to be formally described, Obovaria cf. unicolor (Inoue et al. 2013, pp. 2670-2683). Genetics work by the U.S. Geological Survey (USGS) is upcoming to resolve the taxonomic uncertainty. In the SSA report, we evaluated both the Alabama hickorynut and Obovaria cf. unicolor because the petitioned entity included the entire range of both species and because Obovaria cf. unicolor has not yet been formally described. Both species have a lifespan of 20 to 44 years. The two entities are allopatric, meaning they occur in separate, non-overlapping geographical areas. In the SSA report, we have assumed similarities between the two species in biology and ecology, but we have assessed their differences in geographic occupancy and threats faced.

The Alabama hickorynut ( Obovaria unicolor) has a generally round to oval shape with a moderately thick shell. The species is moderately inflated and grows up to a length of 50 to 70 millimeters (mm). Males grow to be slightly larger than females (Haag and Rypel 2011, pp. 225-247). Posterior and anterior margins are rounded. The umbo is inflated and elevated above the hinge line (Williams et al. 2008, pp. 476-477; Haag, from Mirarchi et al. 2004, p. 99). The lateral teeth are short and straight. The pseudocardinal teeth are triangular and erect with two divergent teeth in the left valve and one in the right valve. The nacre inside the shell is usually white but occasionally pink (Williams et al. 2008, pp. 476-477). Obovaria cf. unicolor has yet to be formally described, but has a similar morphology to Alabama hickorynut.

The Alabama hickorynut and Obovaria cf. unicolor occupy large creeks and streams to large rivers with sand, gravel, and silt substrates in slow to moderate current (Williams et al. 2008, p. 477; Mirarchi et al. 2004, p. 99). Historically, the Alabama hickorynut occupied the mainstem of the Tombigbee and Alabama Rivers along with their associated large tributaries. Obovaria cf. unicolor historically occupied the mainstem and associated large tributaries of the Pascagoula, Pearl, Tangipahoa, Tickfaw, and Amite Rivers. Occurrence data collected over time indicate that both species were historically found in low densities and were relatively rare in mussel assemblages.

The Alabama hickorynut and Obovaria cf. unicolor have complex life cycles that rely on fish hosts for successful reproduction, similar to other mussels. Both species are long-term brooders, gravid from August to the following June, with glochidia being fully developed by November (Haag and Warren 2003, p. 83). Several host fish species have been documented for the Alabama hickorynut and Obovaria cf. unicolor, and all host fishes appear to be relatively common species of darters (Percidae) of the genera Ammocrypta, Etheostoma, and Percina.

Regulatory and Analytical Framework

Regulatory Framework

Section 4 of the Act (16 U.S.C. 1533) and the implementing regulations in title 50 of the Code of Federal Regulations set forth the procedures for determining whether a species is an endangered species or a threatened species, issuing protective regulations for threatened species, and designating critical habitat for endangered and threatened species.

The Act defines an “endangered species” as a species that is in danger of extinction throughout all or a significant portion of its range, and a “threatened species” as a species that is likely to become an endangered species within the foreseeable future throughout all or a significant portion of its range. The Act requires that we determine whether any species is an endangered species or a threatened species because of any of the following factors:

(A) The present or threatened destruction, modification, or curtailment of its habitat or range;

(B) Overutilization for commercial, recreational, scientific, or educational purposes;

(C) Disease or predation;

(D) The inadequacy of existing regulatory mechanisms; or

(E) Other natural or manmade factors affecting its continued existence.

These factors represent broad categories of natural or human-caused actions or conditions that could have an effect on a species' continued existence. In evaluating these actions and conditions, we look for those that may have a negative effect on individuals of the species, as well as other actions or conditions that may ameliorate any negative effects or may have positive effects.

We use the term “threat” to refer in general to actions or conditions that are known to or are reasonably likely to negatively affect individuals of a species. The term “threat” includes actions or conditions that have a direct impact on individuals (direct impacts), as well as those that affect individuals through alteration of their habitat or required resources (stressors). The term “threat” may encompass—either together or separately—the source of the action or condition or the action or condition itself.

However, the mere identification of any threat(s) does not necessarily mean that the species meets the statutory definition of an “endangered species” or a “threatened species.” In determining whether a species meets either definition, we must evaluate all identified threats by considering the species' expected response and the effects of the threats—in light of those actions and conditions that will ameliorate the threats—on an individual, population, and species level. We evaluate each threat and its expected effects on the species, then analyze the cumulative effect of all of the threats on the species as a whole. We also consider the cumulative effect of the threats in light of those actions and conditions that will have positive effects on the species, such as any existing regulatory mechanisms or conservation efforts. The Secretary determines whether the species meets the definition of an “endangered species” or a “threatened species” only after conducting this cumulative analysis and describing the expected effect on the species.

The Act does not define the term “foreseeable future,” which appears in the statutory definition of “threatened species.” Our implementing regulations at 50 CFR 424.11(d) set forth a framework for evaluating the foreseeable future on a case-by-case basis, which is further described in the 2009 Memorandum Opinion on the foreseeable future from the Department of the Interior, Office of the Solicitor (M-37021, January 16, 2009; “M-Opinion,” available online at https://www.doi.gov/sites/doi.opengov.ibmcloud.com/files/uploads/M-37021.pdf ). The foreseeable future extends as far into the future as the U.S. Fish and Wildlife Service and National Marine Fisheries Service (hereafter, the Services) can make reasonably reliable predictions about the threats to the species and the species' responses to those threats. We need not identify the foreseeable future in terms of a specific period of time. We will describe the foreseeable future on a case-by-case basis, using the best available data and taking into account considerations such as the species' life-history characteristics, threat projection timeframes, and environmental variability. In other words, the foreseeable future is the period of time over which we can make reasonably reliable predictions. “Reliable” does not mean “certain”; it means sufficient to provide a reasonable degree of confidence in the prediction, in light of the conservation purposes of the Act.

Analytical Framework

The SSA report documents the results of our comprehensive biological review of the best scientific and commercial data regarding the status of the species, including an assessment of the potential threats to the species. The SSA report does not represent our decision on whether the species should be proposed for listing as endangered or threatened species under the Act. However, it does provide the scientific basis that informs our regulatory decisions, which involve the further application of standards within the Act and its implementing regulations and policies.

To assess the viability of Alabama hickorynut and Obovaria cf. unicolor, we used the three conservation biology principles of resiliency, redundancy, and representation (Shaffer and Stein 2000, pp. 306-310). Briefly, resiliency is the ability of the species to withstand environmental and demographic stochasticity (for example, wet or dry, warm or cold years), redundancy is the ability of the species to withstand catastrophic events (for example, droughts, large pollution events), and representation is the ability of the species to adapt to both near-term and long-term changes in its physical and biological environment (for example, climate conditions, pathogens). In general, species viability will increase with increases in resiliency, redundancy, and representation (Smith et al. 2018, p. 306). Using these principles, we identified the species' ecological requirements for survival and reproduction at the individual, population, and species levels, and described the beneficial and risk factors influencing the species' viability.

The SSA process can be categorized into three sequential stages. During the first stage, we evaluated the individual species' life-history needs. The next stage involved an assessment of the historical and current condition of the species' demographics and habitat characteristics, including an explanation of how each species arrived at its current condition. The final stage of the SSA involved making predictions about the species' responses to positive and negative environmental and anthropogenic influences. Throughout all of these stages, we used the best available information to characterize viability as the ability of a species to sustain populations in the wild over time, which we then used to inform our regulatory decision.

The following is a summary of the key results and conclusions from the SSA report; the full SSA report can be found at Docket No. FWS-R4-ES-2024-0130 on https://www.regulations.gov.

Summary of Biological Status and Threats

In this discussion, we review the biological conditions of the species and their resources, and the threats that influence the species' current and future conditions, in order to assess each species' overall viability and the risks to that viability.

Population and Species Needs

The individual, population-level, and species-level needs of the species are summarized below in table 1. For additional information, please see the SSA report (Service 2023, pp. 19-20). Briefly, for populations to be sufficiently resilient, they must have adequate water quality, natural flow regimes, stable habitat, and substrates on a larger scale. Connectivity is also an important factor for populations because it facilitates gene flow within and among populations, thereby promoting adaptive potential, and it enables movement and dispersal of individuals to suitable habitat. Natural flow regimes are an important resource need for Alabama hickorynut and Obovaria cf. unicolor populations as flows are a habitat requirement for all life stages. More specifically, the species require flowing water for sheltering (habitat requirement), feeding, reproduction, and dispersal. Altered flow regimes may thus cause decreased spawning, recruitment, and survival. Adequate water quality is a need at the individual level for sheltering, reproduction, and feeding (to ensure food source is present). Stable habitat, and in particular the presence of stable sand, gravel, and silt substrates, is an important resource need for sheltering and feeding, especially for juveniles and adults due to their limited movement and dispersal abilities during these life stages. At the species level, both species need a sufficient number and distribution of healthy populations to withstand environmental and demographic stochasticity (resiliency), withstand catastrophes (redundancy), and adapt to biological and physical changes in their environment (representation). Genetic diversity should be high enough that the species will be able to adapt to changing environmental factors through the process of natural selection.