Assisted Migration Workshop - Case Study

Transcription

1 Assisted Migration Workshop - Case Study Species/populations involved: Banbury Springs Lanx Case study location: Thousand Springs, Idaho Actual or hypothetical: Actual Climate change projections for species: Climate change may impact quantity and timing of runoff into the Snake River Plain Aquifer (SRPA), which would affect quantity and quality of water exiting springs. Reduced snow pack could result in increased groundwater pumping to meet agricultural demands, reducing discharge at occupied springs. Key threats to species & associated habitats (not just related to climate change projections): Declining SRPA quantity and quality. Small and isolated populations; no opportunity for exchange of individuals. Water diversions; affects certain populations more than others. Increasing macrophyte presence; limit available suitable habitat for the species Proposed or potential assisted migration scenario: Background: The Banbury Springs limpet or lanx (Lanx sp.) is an endemic, lymnaeid gastropod that occurs in 4 small populations in spring creeks along the middle Snake River in Idaho. In 2008, the IFWO began a structured monitoring effort at the Banbury Springs population, followed by monitoring of the other 3 populations in While some of these populations have varied in size between years, all have declined since monitoring began. Of these, the Thousand Springs Population is currently the smallest of the four populations, with only 15 individuals recorded during the 2015 monitoring effort; an early survey (1991) estimated the Thousand Springs population to contain between 600 and 1200 individuals. Frest and Johannes described the species as occupying an area of m 2 in 1991, but most individuals are now restricted to an area of <2 m 2. These declines may have been driven by reduced water quality from the SRPA, including increasing nitrate concentrations over time, and excessive macrophyte growth which smothers the open cobble habitat preferred by this limpet. Irrespective of the cause of decline, the Thousand Springs population has reached such low numbers, that both genetic bottle-necking and inbreeding, as well as demographic stochasticity could now quickly drive this population to extinction. In an effort to see if reduced genetic variation could explain some of the observed decline and to assess if increasing that variation could be used as a conservation tool, the Idaho Fish & Wildlife Office (IFWO) is proposing that limpets be moved from larger populations to Thousand Springs in an effort to implement a genetic rescue. The below protocol explains how this effort is to be undertaken. Process: Freshwater snails in the genus Lanx are extremely sensitive to water quality and a successful translocation requires assessments of habitat conditions between the donor and recipient population which will be done by conducting water chemistry analysis prior to the translocation. The translocation effort will also require rapid transport and release of individuals to ensure stress is minimized. A pilot translocation effort, using surrogate species (pebble snails), will be conducted prior to the limpet

2 translocation in order to assess methods and survivorship. The following translocation protocol provides details on the means we will employ to attempt a successful translocation effort. Other necessary steps in the authorized translocation of these endangered snails, internal Section 7 consultation and modification of the IFWO s Section 10 recovery permit, are being carried out in order to expedite this process. As envisioned, the project will be carried out for 2-3 years and involve intensive follow-up monitoring to assess success of the translocation effort. We are proposing that these translocations be carried out in spring-summer of 2016 and 2017, with preparatory studies being conducted in the fall of 2015 and early spring of Fifteen to 20 individual limpets will be transported from a donor population to the recipient population (Thousand Springs) on cobbles to which those individuals are attached at the time of their collection. All cobbles and snails to be translocated will be tagged with non-toxic markers. Post-translocation monitoring will be carried out at the release site both for short-term and long-term. Short term monitoring will include immediate follow-up monitoring and continue for up to 1 month after release. Short term monitoring will include: 1) periodic inspection of the limpets on the translocated cobbles for the first 1-2 hours after cobble placement in the recipient population; 2) inspection of the translocated cobbles and limpets the day following the translocation event; 3) inspection of cobbles, limpets, and the surrounding benthic substrates one week after the translocation event; and 4) inspection of cobbles, limpets, and the surrounding benthic substrates one month after the translocation event. Other context/issues to consider: The Banbury Springs lanx is currently undescribed (Lanx sp.), but it is being proposed as a new genus and species (Idaholanx fresti) based on morphological and genetic analysis (Campbell et al., in review). Genetic data between the 4 known populations is lacking. The State of Idaho has an active groundwater recharge program for the SRPA. It is unknown at this point what effect this may have on the species due to the water quality of the recharge water being used. The SRPA is intensively used by several large industries in southern Idaho, including confined animal feeding operations (CAFO), farming, and aquaculture. The number of CAFOs have increased dramatically, which has led to increased waste management concerns (spreading and storing manure on adjacent agricultural fields), as well as aquifer infiltration. Idaholanx fresti Range

3 Species/populations involved: Bull Trout Assisted Migration Workshop Case Study Case study location: Jarbidge River in northern Nevada Actual or hypothetical: Actual Key threats to species & associated habitats (not just related to climate change projections): Bull trout have cold thermal niches and usually require large habitat networks in headwater mountain streams to persist. However, small bull trout populations persist in 6 7 short sections of stream (200 m 2 km in length) in the headwaters of the Jarbidge River in Nevada (Figure 1). Those populations are the southernmost that currently persist within the species North American range, which extends northward through British Columbia and Alberta. Jarbidge bull trout are isolated from the nearest conspecific populations by ~300 river miles and are genetically distinct, suggesting they have been isolated for thousands of years. Bull trout are also often vulnerable to invasions by non-native brook trout, although this species does not currently occur in Jarbidge streams. Climate Projections for species: Stream temperature and habitat suitability models predict that the small habitats currently supporting Jarbidge bull trout are likely to disappear by the end of the century due to climate warming and possibly environmental stochasticity associated with wildfires or drought. Proposed or potential assisted migration scenario: Stream temperature and habitat suitability models show that large stream and river habitats with high probabilities of supporting bull trout occur in western Wyoming outside of the species historical range (Figure 2). Climate projections suggest the Wyoming habitats would remain highly suitable for bull trout even under extreme climate change scenarios. Should bull trout be introduced to Wyoming streams? Figure 1. Stream temperatures (left panels) and bull trout habitat suitability (right panels) for streams in the Jarbidge River headwaters during baseline and late century climate periods.

4 Figure 2. Summer stream temperature scenario for a baseline climate period ( ) showing Jarbidge habitats relative to potential habitats in Wyoming.

5 Assisted Migration Workshop - Case Study Species/populations involved: Oregon spotted frog (Rana pretiosa) Case study location: Central Oregon, Deschutes River Basin Actual or hypothetical: Hypothetical Photo 1: Female Oregon spotted frog. Map of Location Photo 2: Example of wetlands between populations. Photo 3: Wetland within designated critical habitat that is currently void of water through winter.

6 Climate change projections for species: PNW warming trend is predicted in models. The majority of models project wetter winters and drier summers, and a reduction in regional snowpack. Snowmelt-dominated watersheds such as the Deschutes Basin may become transient, resulting in increased winter streamflow and reduced spring and summer flows. Changes may affect amphibians through a variety of direct and indirect pathways, such as range shifts, breeding success, survival, dispersal, breeding phenology, availability and quality of aquatic habitats, food webs, competition, spread of diseases, and the interplay among these factors. Predators such as bull frogs that have a preference for warm water habitat could further expand distribution into Oregon spotted frog (OSF) habitat. Key threats to species & associated habitats (not just related to climate change projections): Water management Reed canary grass Vegetation encroachment Bull frogs and non-native fish Small population size Isolation and loss of connectivity between populations /habitats Proposed or potential assisted migration scenario: The current distribution of Oregon spotted frogs downstream of Wickiup Dam is limited to only a handful of sites along 60 miles of river. Most of these OSF sites are dewatered when water is stored in reservoirs for irrigation from October through April and connectivity between sites (i.e., populations) has been diminished. The Service is negotiating a Habitat Conservation Plan with 8 irrigation districts in the Deschutes River Basin and a long-term permit (e.g., ~30 years) issuance for take is anticipated. The expected outcome will involve improving flows in the Deschutes River and adjacent wetlands over time. Improved hydrologic conditions along this reach of the river as a result of the HCP may restore suitable wetlands but distances from current populations are too large (>5km or 3.1 miles) for natural recolonization and in some cases natural barriers (i.e., waterfalls) prevent migration to habitat upstream of existing populations. Other context/issues to consider: Is the translocation part of an integrated conservation and recovery strategy? Has the suitability of sites (i.e., lack of threats) been fully assessed, including within the context of climate change? Is movement within current range to necessary to enhance connectivity? Will translocation improve genetic exchange between populations? Is ongoing management needed to maintain suitability of sites and populations?

7 Native minnows in the Umpqua Basin Species/populations involved: Native minnows in the Umpqua River basin, including endemic Umpqua chub, Umpqua pikeminnow, and Umpqua dace. These three species are among the top 10 rarest fishes in the state of Oregon. Case study location: Umpqua River, southwestern Oregon. Actual or hypothetical: Actual Climate change projections for species: NorWeST climate projections indicate warming across stream networks within the Umpqua basin, with greater warming in inland portions of the basin. Key threats to species & associated habitats (not just related to climate change projections): Nonnative warmwater fish invasions (ecological interactions) Movement barriers Inadequate regulatory action Proposed or potential assisted migration scenario: Translocation of species above vertical barriers within the Umpqua basin to movement or upstream of thermal barriers to warmwater invasion Concerns and uncertainties: Climate projections Listing of species in question Species status Suitability of donors Persistence above barriers Impacts to other valued species (e.g., salmonids, Pacific lamprey) Value of nonnatives Efficacy of alternatives (e.g., removal of nonnatives) Effects on other restoration activities Instream habitat Passage Umpqua pikeminnow