Considerations for Conservation Translocation Policies

August 8, 2022

U.S. Fish and Wildlife Service
5275 Leesburg Pike
Falls Church, VA 22041-3803

Re: Endangered and Threatened Species: Designation of Experimental Populations, Docket No. FWS-HQ-ES-2021-0033-0001

Dear Sir or Madam:

The American Fisheries Society (AFS) respectfully submits the following comments in response to the proposed changes to section 10(j) of the Endangered Species Act (ESA), Docket No. FWS-HQ-ES-2021-0033-0001, submitted by the U.S. Fish and Wildlife Service for public comment on June 7, 2022.

AFS represents over 7,500 professional fishery scientists and resource managers who work in the private sector, academic institutions, and in tribal, state, and federal agencies. Our common mission is to improve the conservation and sustainability of fishery resources and aquatic ecosystems by advancing fisheries and aquatic science and promoting the development of fisheries professionals.

Section 10(j) of the ESA concerns the use of experimental populations as a conservation tool. At its current standing the translocations of species is limited to historic ranges, unless under the extreme circumstance in which the primary habitat has been irreversibly destroyed or altered to make unsuitable. As you consider proposed changes to section 10(j) that would allow for introduction of experimental populations outside of historic ranges in the absence of emergency (e.g. unexpected contamination, disease, habitat destruction, unprecedented mass deaths, or extreme climatic changes), we submit the following science-based guidelines and best practices to inform the development of the rule. We appreciate the opportunity to comment.

Conservation translocations are a global conservation tool intended to aid in the recovery and long-term preservation of threatened and endangered populations. In the U.S., reintroductions have helped to restore a number of species (Novak et al. 2021). Indeed, conventional conservation measures such as habitat restoration in a species’ original range may be insufficient in the face of rapid climate change. Climate change has already caused increased range constrictions, shifts in suitable habitat, and increased fragmentation for many species leading to increased extinction risk (Hoegh-Guldberg et al. 2008; Chen et al., 2011). Many species do not have the ability to adapt or move in response to climate change. For those that do, their ability to cover the necessary geographical distance may be inadequate (Butt et al. 2020).

Trends in shifting ranges are generally towards the poles and to higher altitudes. Natural and anthropogenic barriers can impede a species ability to range shift (Chen et al. 2011; Scheffers and Pecl 2019). The intentional movement of species outside of its native/historical range, often termed assisted colonization, assisted migration, or managed relocation, could be critical for preventing extinction (McLachlan et al. 2007; Hoegh-Guldberge et al. 2008; Ricciardi and Simberloff 2009; Richardson et al. 2009; Shirey and Lamberti 2010). However, concerns have been raised regarding the use of assisted colonization and it has thus far been considered a conservation measure of last resort (Hoegh-Guldberg et al. 2008; Butt et al. 2020). Assisted colonization as a conservation tool must be an iteratively informed process, involve a nuanced understanding of species and ecosystem specific criteria, embrace community, industry, scientific, and indigenous input and continued partnership, and include a rigorous scientific monitoring program designed to study holistic chemical, physical, and biological ecosystem interactions. The primary habitat restriction under the section 10(j) regulations (50 C.F.R. §17.81) is a challenging standard to overcome from a scientific perspective when planning for climate change because the agency did not define the degree of habitat change that results in an “unsuitable and irreversible alteration” (Shirey and Lamberti 2010).

Negative impacts
Negative impacts on the recipient ecosystem are major concerns regarding assisted colonization and has been a key factor in arguments against the use of assisted colonization. Whether it’s re-introduction or new introduction, translocations alter the bio-abundance and biodiversity of an ecosystem. These alterations can range in impact from short-term low impact to systemically transformative, and be beneficial or harmful (IUCN/SSC, 2013). Nature is unpredictable and how species and ecosystems will interact cannot be wholly predicted. We recommend taking precautionary approaches when introducing a species outside their native range. Rigorous risk assessments should be used to determine the negative consequences associated with the risk to the target species as well as the risk to the recipient ecosystem.

Any removal of individuals from a source population will decrease the available genetic diversity within that population. Though very rare, this could result in negative impacts for the source population. At-risk species generally already suffer from decreased genetic diversity (Willoughby et al. 2015; Furlan et al. 2019). The founder individuals should be selected form a source population that is genetically fit while also avoiding the possibility of inbreeding or outbreeding depression. Monitoring of both the genetic fitness for the source and the experimental populations is important to ensure the health of both and allow for low-level human mediation if necessary (IUCN/SSC 2013; McLennan et al. 2020).

Harm done to recipient ecosystems is a major concern for the movement of species outside of their historic range (IUCN/SSC 2013). As of 2021, there has been only one case where a conservation translocation resulted in negative unintended consequences (Novak et al. 2021). The U.S. Fish and Wildlife Service translocated a population of 200 endangered Watercress Darters (Etheostoma nuchale) to Tapawingo Spring, which was outside of the taxon’s native range. This translocation resulted in the local extirpation of the Tapawingo Darter (E. phytophilium), which had been previously thought to be a more common taxon, the E. parvipinne (Bart Jr. & Taylor, 1999; George et al., 2009). Unfortunately, the Tapawingo Darter is only found in three Alabama counties, and the impact of this loss was significant (Novak et al., 2021). This is a prime example of the concerns regarding assisted colonization, and while this is a rare occurrence, steps should be taken to mitigate this risk. Biological and risk assessments done on the recipient ecosystem should include genomic sequences of species that could be impacted by the introduction of the target species, such as prey or competition species, to help ensure that species with restricted ranges, like with the Tapawingo Darter are correctly managed and protected.

Introduction of novel pathogens and parasites is another area of concern that can pose particularly vast consequences to both the target species and the recipient ecosystem (Schaumburg et al. 2012; Sherman et al. 2021). Immunosuppression from the stress of transportation for translocated individuals leaves them vulnerable to diseases that exist in the recipient ecosystem (Kock et al. 2010). Even individuals that are not immunosuppressed are vulnerable to novel pathogens and parasites (Carroll et al. 2009). There is also the risk of the translocated individuals introducing novel pathogens into the recipient ecosystem (Sainsbury et al. 2012). While there is disease screening, we can only screen for what we know. Disease risk analyses should be performed prior to the translocation on not only the candidate ecosystem but to surrounding areas as well (Hartley and Sainsbury 2017). It is not uncommon for translocated individuals to move outside of the release site (Heezik et al. 2009). The movement of animals through the recipient ecosystem is also something that cannot be wholly controlled and needs to be accounted for. Including behavioral assessments into risk analyses will allow decision makers to determine how the introduced individuals will directly interact with other species and indirectly through their environment. This will assist in predicting possible pathways that pathogens and parasites could be transmitted and allow for appropriate monitoring (Sainsbury et al. 2012). As information is gained after the release of the experimental populations, risk assessments should be updated, and management altered to reflect the most recent knowledge (Shotton and Sainsbury 2015). If, however, the impacts from assisted colonization exceed what is considered acceptable levels of harm, there needs to be clear mitigation strategies. This includes either the removal or termination of the introduced species, as well as action plans for restoration of the recipient ecosystem, and should be included in the overall estimated project cost (Schwartz and Martin 2013).

Habitat Selection
Species translocation includes risk of hybridization, introducing pathogens not native to an area, and extirpation of other species via competition (Shirey et al. 2013). For example, In Hawaii, two endangered species of Hibiscadelphus that had natural allopatric distributions were brought together in Hawaii Volcanoes National Park to help preserve each species. Cross-fertilization created a vigorous hybrid population that had to be eliminated in addition to eliminating the introduced Hibiscadelphus hualalaiensis to protect remaining Hibiscadelphus giffardianus trees (Baker and Allen 1977). However, waiting until habitat is unsuitably or irreversibly altered or destroyed before planning translocation also caries risk of extinction which the ESA is designed to prevent. Thus, creating a best practice framework for the assessment of possible habitats is crucial to identifying risks, avoiding unintended consequences, determining appropriate monitoring, and ensuring support. Habitats are species-specific systems of abiotic and biotic components that vary over space and time (Osborne and Seddon 2012; IUCN/SSC 2013).

The candidate site must meet a species climatic need and those needs must be met throughout seasonal shifts. Environmental conditions can drastically shift with the seasons. The extremes that the candidate site displays, must not exceed the tolerance limits of the species. For example. water levels in rivers determines the rate of flow, ability to migrate, and controls the temperature. For some species there is a thermal tolerance limit, meaning that if the water temperature increases above that limit they will not survive (McCullough 1999; Mantua et al. 2010). Precipitation, both timing and type, are necessary for certain environmental processes and influence available vegetation (Clifton et al. 2018). All of these factors change with the season, and candidate sites need to meet the need of the species throughout these changes.

Habitat selection must also consider the biotic components of a habitat and meet the behavioral needs of the experimental population. Factors such as predator-prey interactions, competition, and habitat selection all determine suitability of candidate sites. These behaviors can also change depending on the life history stage of the individual (Picardi et al. 2021). Understanding the nuances of these factors and how they change can help ensure successful experimental populations. Post-release dispersal behavior is one reason for translocation failure. In some species dispersal is sex biased (Angelstam and Sandegren 1982; Spinola et al. 2008; Dolev et al. 2002), while in others age plays a role (Scherzinger 1978; Gouar et al. 2012). Altering the composition of the experimental population could account for these nuances and can help reduce risks.

Assessments of candidate habitats need to include both the environmental needs, as well as behavioral needs, and projections for how climate change will impact these factors. All of these factors need to be assessed for all life history stages. The goal of experimental populations is to have self-sufficient established populations, that means that all life history stages must be able to survive.

Monitoring should reflect the specified set objectives of the translocation. Those objectives should focus on both the experimental population as well as the recipient ecosystem. A successful translocation should allow for the experimental population to thrive without detriment to the ecosystem they are introduced.

Pre-release monitoring aids in selection of candidate ecosystems and provides baseline data of both the recipient ecosystem and the source population for post-release comparisons (Osborne and Seddon 2012; Nichols & Armstrong 2012; IUCN/SSC 2021). Understanding predator-prey interactions, ecosystem functions, and the biodiversity of the recipient ecosystem prior to introduction is important for determining the impact of the experimental population. Pre-release monitoring should be robust, but also reflect the species and their needs. For example, if the experimental population is aquatic, soil nutrient profiles may not be necessary, but water chemistry profiles would be (Mantua et al. 2010; IUCN/SSC 2021). Ecosystems are incredibly dynamic, and the impacts of small changes are not always understood. Obtaining detailed baseline date for ecosystems help aid in ensuring negative impacts do not occur, as well as provide information for future projects (IUCN/SSC 2013).

Post-release monitoring presents its own set of challenges. Monitoring techniques should not cause significant disturbance to the target species and should avoid long-term habitat degradation (IUCN/SSC 2013). Some monitoring methods will be less invasive, such as those for behavioral assessments where the use of drones and cameras have aided in non-invasive practices, can occur more frequently. Others, such as genetic and health monitoring, that may require biological samples, would occur on a different frequency scale (Ewen et al. 2012). Negative consequences could go hidden if the length of monitoring is too short or insufficient (Nichols and Armstrong 2012). For example, novel diseases could take years before the consequences are detectable (Sainsbury et al. 2012). Another example is the invasive tree, Acacia longifolia, that was found to systemically alter the original native ecosystem of coastal dunes in Portugal. While these changes were detectable for recent (10 year) invasions, they were much more apparent at a long-term (20 years) invasion scale (Marchante et al. 2008). Length of monitoring and the frequency of sampling methods should reflect the life-history of the species, ecosystem cycles, and identified threats (Sainsbury et al. 2012; IUCN/SSC 2021).

In conclusion, with the use of best available practices, science-based guidelines, and monitoring, successful establishment of experimental populations outside of historical ranges could be a beneficial conservation tool in the face of climate change.

Thank you for the opportunity to comment.


Douglas J. Austen, Ph.D.
Executive Director


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