SEARCH · Geology Reports

Results for “Research Status Report”

Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 289 records · Page 16Linked to original sources

USGS1980

The Rocky Mountain population of the western Canada goose: Its distribution, habitats, and management

The western Canada goose ( Branta canadensis moffitti ) was divided into a Rocky Mountain population (RMP) and a Pacific population (PP) on the basis of band recovery patterns examined in this study and recovery data from other investigators. Habitat information obtained from nine cooperating wildlife agencies within the RMP's range provided a base line for evaluating future changes in nesting, molting, and wintering areas. The habitat inventory indicated that none of the seasonal habitats were currently limiting the size of the RMP. The RMP's range is divided into 15 reference areas and these are briefly described. Past studies of Canada geese in the Intermountain Region are reviewed. Topics covered in the discussion of breeding biology are nesting chronology, spring population composition, breeding age, clutch size, nesting success. artificial nesting structures, and gosling survival. Much of the mortality of Canada geese occurs before the birds are fledged. Man-made nesting structures reduce losses during incubation. but research is needed on the relations between brooding sites and gosling survival. Some western Canada geese, mainly prebreeders and unsuccessful nesters, make molt migrations to and from molting areas during and after the brood-rearing season. More than half of these molt-migrants are yearlings too young to nest; there are indications that even some successful nesters leave nesting areas to molt before the fledging of their offspring. Geese 2 years old or older may serve as guides to traditional molting areas for the first-time migrants (i.e., yearlings). Lack of disturbance appears to influence selection of specific molting areas within the nesting range of moffitti , whereas movements of molters out of the Intermountain Region may be related to the evolution of this subspecies. Apparently. molters of both the PP and RMP that leave the Region go to the Northwest Territories of Canada. Although the taxonomic status of moffitti as related to the giant Canada goose ( B. c. maxima ) is unclear. these two subspecies are closely related. as evidenced by similar molt migrations to subarctic Canada. similar blood serum proteins. and only dinal differences in body size ,!!nd color. Mean annual survival rates for birds banded on nesting areas averaged 53 ± 2% ( X̿ ± SE) for immatures and 64 ± 1 % for adults. Mean annual survival rates of adults captured on molting areas averaged 70 ± 1 %. Sport hunting accounts for more than 86% of the mortality of fledged Rocky Mountain geese. and hunting may limit the population's growth. Because the number of waterfowl hunters in the Rocky Mountain West is increasing, the continued expansion or future maintenance of the RMP may require more restrictive hunting regulations. Other management recommendations include the refinement and standardization of spring and winter aerial surveys, and more accurate age and sex determinations when geese are banded and color-marked.

Alberta, Arizona, California, Colorado, Idaho, Mon↗

USGS2011

Status and distribution of the Kittlitz's Murrelet Brachyramphus brevirostris along the Alaska Peninsula and Kodiak and Aleutian Islands, Alaska

The Kittlitz's Murrelet Brachyramphus brevirostris is adapted for life in glacial-marine ecosystems, being concentrated in the belt of glaciated fjords in the northern Gulf of Alaska from Glacier Bay to Cook Inlet. Most of the remaining birds are scattered along coasts of the Alaska Peninsula and Aleutian Islands, where they reside in protected bays and inlets, often in proximity to remnant glaciers or recently deglaciated landscapes. We summarize existing information on Kittlitz's Murrelet in this mainly unglaciated region, extending from Kodiak Island in the east to the Near Islands in the west. From recent surveys, we estimated that ~2400 Kittlitz's Murrelets were found in several large embayments along the Alaska Peninsula, where adjacent ice fields feed silt-laden water into the bays. On Kodiak Island, where only remnants of ice remain today, observations of Kittlitz's Murrelets at sea were uncommon. The species has been observed historically around the entire Kodiak Archipelago, however, and dozens of nest sites were found in recent years. We found Kittlitz's Murrelets at only a few islands in the Aleutian chain, notably those with long complex shorelines, high mountains and remnant glaciers. The largest population (~1600 birds) of Kittlitz's Murrelet outside the Gulf of Alaska was found at Unalaska Island, which also supports the greatest concentration of glacial ice in the Aleutian Islands. Significant populations were found at Atka (~1100 birds), Attu (~800) and Adak (~200) islands. Smaller numbers have been reported from Unimak, Umnak, Amlia, Kanaga, Tanaga, Kiska islands, and Agattu Island, where dozens of nest sites have been located in recent years. Most of those islands have not been thoroughly surveyed, and significant pockets of Kittlitz's Murrelets may yet be discovered. Our estimate of ~6000 Kittlitz's Murrelets along the Alaska Peninsula and Aleutian Islands is also likely to be conservative because of the survey protocols we employed (i.e. early seasonal timing of surveys, strip transects).

Alaska↗

USGS2002

Harlequin duck ( Histrionicus histrionicus ) perspective: Harlequin duck population recovery following the Exxon Valdez oil spill: Progress, process, and constraints

Following the 1989 Exxon Valdez oil spill in Prince William Sound, Alaska, we studied the status of recovery of harlequin duck ( Histrionicus histrionicus ) populations during 1995-1998. We evaluated potential constraints to full recovery, including (1) exposure to residual oil, (2) food limitation, and (3) intrinsic demographic limitations on population growth rates. In this paper, we synthesize the findings from our work and incorporate information from other harlequin duck research and monitoring programs to provide a comprehensive evaluation of the response of this species to the Exxon Valdez oil spill. We conclude that harlequin duck populations had not fully recovered by 1998. Furthermore, adverse effects continued as many as 9 years after the oil spill, in contrast to the conventional paradigm that oil spill effects on bird populations are short-lived. These conclusions are based on the findings that (1) elevated cytochrome P450 induction on oiled areas indicated continued exposure to oil in 1998, (2) adult female winter survival was lower on oiled than unoiled areas during 1995-1998, (3) fall population surveys by the Alaska Department of Fish and Game indicated numerical declines in oiled areas during 1995-1997, and (4) densities on oiled areas in 1996 and 1997 were lower than expected using models that accounted for effects of habitat attributes. Based on hypothesized links between oil contamination and demography, we suggest that harlequin duck population recovery was constrained primarily by continued oil exposure. Full population recovery also will be delayed by the time necessary for intrinsic population growth to allow return to pre-spill numbers following cessation of residual oil spill effects. Although not all wildlife species were affected by the Exxon Valdez oil spill, and some others may have recovered quickly from any effects, harlequin duck life history characteristics and benthic, nearshore feeding habits make them susceptible to both initial and long-term oil spill effects.

Alaska↗

USGS2020

Southern (California) sea otter population status and trends at San Nicolas Island, 2017–2020

The southern sea otter ( Enhydra lutris nereis ) population at San Nicolas Island, California, has been monitored annually since the translocation of 140 sea otters to the island was completed in 1990. Monitoring efforts have varied in frequency and type across years. In 2017, the U.S. Navy and the U.S. Fish and Wildlife Service initiated a sea otter monitoring and research plan to determine the effects of military readiness activities on the growth or decline of the southern sea otter population at San Nicolas Island. The monitoring program, at its basic level, includes quarterly seasonal surveys of population abundance, distribution, and foraging activity. From 2017 to 2020, we measured a 22-percent per annum increase in population abundance (95-percent confidence interval =11–34 percent) with 114 total individuals as of February 2020. Coinciding with recent population growth, the sea otter distribution, which previously tended to concentrate on the west side, appears to have shifted toward an expansion of use in the north and especially greater seasonal use in the north and south during winter and spring. Foraging data were collected on a total of 2,675 foraging dives in 167 foraging bouts, and the majority of identified prey on successful dives (n=1,335) were sea urchins (940) followed by snails (240) and crabs (78). Small numbers of lobsters (26), octopus (16), and abalone (5) also were identified. Estimates of energy intake rates averaged 17.3 kilocalories per minute (95-percent confidence interval =15.6–19.0 kilocalories per minute) and suggest possible variations across years and seasons, but confidence intervals based on specific years of data were relatively wide. In addition to abundance, trends, distribution, and forage energy intake across seasons and years, these replicated surveys provide information on the precision of data achieved by quarterly survey effort. We used precision estimates and conducted simulation analyses to assess the power of detecting 10-percent or greater decreases in population growth rates and how this power is likely to change with years of observation, survey effort, and the size of decrease. These results can be useful to the planning of future monitoring and research of sea otters at San Nicolas Island.

California↗

USGS2021

Connectivity of Mojave Desert tortoise populations—Management implications for maintaining a viable recovery network

Executive Summary The historic distribution of Mojave desert tortoises ( Gopherus agassizii ) was relatively continuous across the range, and the importance of tortoise habitat outside of designated tortoise conservation areas (TCAs) to recovery has long been recognized for its contributions to supporting gene flow between TCAs and to minimizing impacts and edge effects within TCAs. However, connectivity of Mojave desert tortoise populations has become a concern because of recent and proposed development of large tracts of desert tortoise habitat that cross, fragment, and surround designated conservation areas. This paper summarizes the underlying concepts and importance of connectivity for Mojave desert tortoise populations by reviewing current information on connectivity and providing information to managers for maintaining or enhancing desert tortoise population connectivity as they consider future proposals for development and management actions. Maintaining an ecological network for the Mojave desert tortoise, with a system of core habitats (TCAs) connected by linkages, is necessary to support demographically viable populations and long-term gene flow within and between TCAs. There are four points for wildlife and land-management agencies to consider when making decisions that could affect connectivity of Mojave desert tortoise populations (for example, in updating actions in resource management plans or amendments that could help maintain or restore functional connectivity in light of the latest information): Management of all desert tortoise habitat for persistence and connectivity . Desert tortoise populations continue to decline within most TCAs, and it is unlikely that trends are better in populations outside protected areas. Fragmentation exacerbates negative population trends by breaking large continuous populations into smaller isolated populations. Connectivity within large populations can enhance resilience to localized disturbances due to rescue by neighboring individuals. In contrast, smaller fragmented populations are resistant to rescue by their isolation and thus could suffer irreversible declines to extirpation from a variety of threats and stochastic events. Enhanced threat reduction to reverse declines within TCAs and to maintain occupied habitat in the surrounding matrix would help reduce the variability in population growth rates and improve the resilience of protected populations even while implementing efforts to improve connectivity. Each TCA has unique strengths and weaknesses regarding its ability to support minimum sustainable populations based on areal extent and its ability to support population increases based on landscape connection with adjacent populations. Considering how proposed projects (inside or outside of TCAs) affect connectivity and the ability of TCAs to support at least 5,000 adult tortoises (the numerical goal for each TCA) could help managers to maintain the resilience of TCAs to population declines. The same project, in an alternative location, could have very different impacts on local and regional populations. For example, within the habitat matrix surrounding TCAs, narrowly delineated corridors may not allow for natural population dynamics if they do not accommodate overlapping home ranges along most of their widths so that tortoises reside, grow, find mates, and produce offspring that can replace older tortoises. In addition, most habitat outside TCAs may receive more surface disturbance than habitat within TCAs. Therefore, managing the entire remaining matrix of desert tortoise habitat for permeability may be better than delineating fixed corridors. These concepts apply, especially given uncertainty about long-term condition of habitat, within and outside of TCAs under a changing climate. Ultimately, questions such as “ What are the critical linkages that need to be protected ?” could be better framed as “ How can we manage the remaining habitat matrix in ways that sustain ecological processes and habitat suitability for special status species ?” Land-management decisions made in the context of the latter question may be more conducive to maintenance of a functional ecological network. Limitations on landscape-level disturbance across habitat managed for the desert tortoise Clearly delineating habitat linkages and differentiating them from non-delineated areas by the uses that are permitted or prohibited within them by specific management guidelines can help achieve functional connectivity. Such guidelines would be most effective if they considered and accounted for all surface disturbances (for example, temporary disturbances such as fiberoptic lines or off-highway vehicle routes, right-of-ways, utility-scale solar development, urbanization) to the extent possible. A weighted framework that varies with the permanence or severity of the disturbance, and can be additive to quantify cumulative effects, could be useful (Xiong, 2020). For example, minor roads can alter tortoise movements independently of other features (Peaden and others, 2017; Hromada and others, 2020), but if the isolated dirt road is accompanied by a powerline that encourages raven predation (Xiong, 2020), then the two features together may be additive. Ignoring minor or temporary disturbance on the landscape could result in a cumulatively large impact that is not explicitly acknowledged (Goble, 2009); therefore, understanding and quantifying all surface disturbance on a given landscape is prudent. In California, the Bureau of Land Management established 0.1–1.0 percent caps on new surface-disturbance for TCAs and mapped linkages that address the issues described in number 1 of this list. Nevada, Utah, and Arizona currently do not have surface-disturbance limits. Limits comparable to those in the Desert Renewable Energy Conservation Plan (DRECP) would be 0.5 percent within TCAs and 1 percent within the linkages modeled by Averill-Murray and others (2013). Limits in some areas of California within the Desert Renewable Energy Conservation Plan, such as Ivanpah Valley, are more restrictive, at 0.1 percent. Continuity across the state line in Nevada could be achieved with comparable limits in the adjacent portion of Ivanpah Valley, as well as the Greater Trout Canyon Translocation Area and the Stump Springs Regional Augmentation Site. These more restrictive limits would help protect remaining habitat in the major interstate connectivity pathway through Ivanpah Valley and focal areas of population augmentation that provide additional population connectivity along the western flank of the Spring Mountains. In a recent study that analyzed 13 years of desert tortoise monitoring data, nearly all desert tortoise observations were at sites in which 5 percent or less of the surrounding landscape within 1 kilometer was disturbed (Carter and others, 2020a). To help maintain tortoise habitability and permeability across all other non-conservation-designated tortoise habitat, all surface disturbance could be limited to less than 5-percent development per square kilometer because the 5-percent threshold for development is the point at which tortoise occupation drops precipitously (Carter and others, 2020a). However, although individual desert tortoises were observed at development levels up to 5 percent, we do not know the fitness or reproductive characteristics of these individuals. This level of development also may not allow for long-term persistence of healthy populations that are of adequate size needed for demographic or functional connectivity; therefore, a conservative interpretation suggests that, ideally, development could be lower. Lower development levels would be particularly useful in areas within the upper 5th percentile of connectivity values modeled by Gray and others (2019). Reducing ancillary threats in places where connectivity is restricted to narrow strips of habitat, for example, narrow mountain passes or vegetated strips between solar development, could enhance the functionality of these vulnerable linkages. In such areas, maintaining multiple, redundant linkages could further enhance overall connectivity. Minimization of mortality from roads and maximization of passage under roads . Roads pose a significant threat to the long-term persistence of local tortoise populations, and roads of high traffic volume lead to severe population declines, which ultimately fragments populations farther away from the roads. Three points (a.–c.) pertain to reducing direct mortality of tortoises on the many paved roads that cross desert tortoise habitat and to maintaining a minimal level of permeability across these roads: Tortoise-exclusion fencing tied into culverts, underpasses, overpasses, or other passages below roads in desert tortoise habitat, would limit vehicular mortality of tortoises and provide opportunities for movement across the roads. Installation of shade structures on the habitat side of fences installed in areas with narrow population-depletion zones would limit overheating of tortoises that may pace the fence. Passages below highways could be maintained or retrofitted to ensure safe tortoise access, for example, by filling eroded drop-offs or modifying erosion-control features such as rip-rap to make them safer and more passable for tortoises. Wildlife management agencies could work with transportation departments to develop construction standards that are consistent with hydrologic/erosion management goals, while also incorporating a design and materials consistent with tortoise survival and passage and make the standards widely available. The process would be most effective if the status of passages was regularly monitored and built into management plans. Healthy tortoise populations along fenced highways could be supported by ensuring that land inside tortoise-exclusion fences is not so degraded that it leads to degradation of tortoise habitat outside the exclusion areas. For example, severe invasive plant infestations inside a highway exclusion could cause an increase of invasive plants outside the exclusion area and degrade habitat; therefore, invasive plants inside road rights of way could be mown or treated with herbicide to limit their spread into adjacent tortoise habitat and minimize the risk of these plants carrying wildfires into adjacent habitat. Adaptation of management based on new information . Future research will continue to build upon and refine models related to desert tortoise population connectivity and develop new ones. New models could consider landscape levels of development and be constructed such that they share common foundations to support future synthesis efforts. If model development was undertaken in partnership with entities that are responsible for management of desert tortoise habitat, it would facilitate incorporation of current and future modeling results into their land management decisions. There are specific topics that may be clarified with further evaluation: The effects of climate change on desert tortoise habitat, distribution, and population connectivity; The effects of large-scale fires, especially within repeatedly burned habitat, on desert tortoise distribution and population connectivity; The ability of solar energy facilities or similar developments to support tortoise movement and presence by leaving washes intact; leaving native vegetation intact whenever possible, or if not possible, mowing the site, allowing vegetation to re-sprout, and managing weeds; and allowing tortoises to occupy the sites; and The design and frequency of underpasses necessary to maintain functional demographic and genetic connectivity across linear features, like highways.

Arizona, California, Nevada↗

USGS2020

Book review: Proceedings of the First International Snakehead Symposium

Snakehead fishes (family Channidae) are among the most maligned aquatic invasive species in the USA and some other countries where they have been introduced outside of their native range in Asia and Africa. Nevertheless, snakeheads continue to be widely exploited in the live‐food trade in aquaculture and wild‐capture fisheries, are highly sought by anglers, and are also popular in the aquarium trade (Courtenay and Williams 2004). The Northern Snakehead Channa argus is the most widespread of the three channid species that are currently naturalized in the USA. This species has generated much concern and controversy, a situation that is partly fueled by sensational media coverage and B‐grade science fiction horror films, such as “Frankenfish,” “Snakehead Terror,” and “Snakehead Swamp.” Media reports of snakehead introductions are often replete with provocative terms, such as “vicious,” “villain,” “voracious,” “monster,” “diabolical,” and even “ecological Armageddon.” When snakeheads first appeared in natural waters of the USA, fisheries professionals became increasingly interested in their status. Established populations rapidly expanded in the mid‐Atlantic region and Arkansas, with scattered reports of introduced snakeheads from isolated locations in Hawaii, California, North Carolina, Florida, the Upper Midwest, and New England. In 2002, snakeheads were added to the list of injurious fishes under the Lacey Act, thereby prohibiting their importation or transport across state lines without a permit. This symposium was conceived by the editors and other concerned fisheries professionals of the Mississippi River Basin Panel on Aquatic Invasive Species. The mission of the symposium, held in Alexandria, Virginia, in July 2018, was to bring together experts on snakehead biology and ecology and to synthesize existing information into summary papers. In this book, 35 authors contributed to 15 peer‐reviewed articles that detail the current state of knowledge about snakehead introductions in the USA. Additionally, 16 abstracts are included from meeting presentations that were not accompanied by full‐length manuscripts. Also included is a summary of a facilitated symposium panel discussion featuring eight experts representing state and federal natural resource agencies and private fishing organizations. The book is organized into six sections. In the first section (Distribution), three papers provide an overview of the Channa species introduced into the USA and historical accounts of occurrence and dispersal of the Northern Snakehead in the mid‐Atlantic region and Arkansas. The second section (Biology/Ecology) consists of two articles that examine growth and energetics of Northern Snakehead populations and two papers that investigate diet, diel feeding activity, and movement of this species in the Potomac River drainage. The third section (Monitoring/Response) includes a paper that models range expansion of the Northern Snakehead in the southeastern USA based on occurrence data and environmental conditions. Also included in this section is a paper summarizing an environmental DNA study to assess the status and range of the Bullseye Snakehead C. marulius in southern Florida. The fourth section (Management/Control) is comprised of four papers that address harvest, age and growth, and development of a stock–recruitment model to inform management decisions regarding control and mitigation for Northern Snakehead populations in the greater Chesapeake Bay area. The fifth section (Perspectives) includes a paper on the history of snakehead introductions in Japan and a thought‐provoking social commentary on the human dimensions of Northern Snakehead management. Abstracts in the final section provide brief summaries of a diversity of snakehead studies, including aspects of distribution, ecology, behavior, control and monitoring efforts, public outreach, and pathology. The summary of the panel discussion is an engaging dialogue about the challenges of snakehead management in the context of conflicts regarding snakeheads as injurious versus their value as game and food species. Most of this book is focused on the Northern Snakehead. Much has been done to document snakehead distributions and certain aspects of snakehead biology, such as diets, age, and growth. Less research has been devoted to understanding the ecological impacts of snakeheads to native aquatic communities and ecosystems. This book would have benefited from a chapter summarizing the current systematics and diversity of the Channidae to inform fisheries biologists about the morphological characteristics of the family, approximate numbers of genera and species, and taxonomic instability. Exemplifying the latter, recent molecular and morphological evidence indicates uncertainty regarding identification of the feral snakehead population in Florida (Adamson and Britz 2019). Those authors suggest that this population may have originated from western Thailand, a possibility that could have implications for understanding historical pathways of snakehead introductions into the USA. In comparison with many published AFS symposia, this volume is relatively narrow in scope and lacks cohesive integration. It will primarily be of interest to those fisheries professionals engaged in the study of snakeheads as well as other nonnative species for which there are contrasting social values regarding their management: whether to monitor and attempt control or eradication efforts or to maintain populations for harvest as game or food species. The book should serve to identify information gaps and guide future research.

Transactions of the American Fisheries Society↗

USGS2019

Cooperative Fish and Wildlife Research Units program—2018 year in review

The Cooperative Fish and Wildlife Research Units (CRU) program had an interesting and challenging year in 2018. We made significant strategic advances on many fronts and had setbacks in others. Our relationship with the U.S. Fish and Wildlife Service, the agency we belonged to from 1935 to the mid-1990s, was further reinforced through strategic efforts with the Service’s Science Applications senior staff. This is bearing fruit in terms of research collaborations and funding support. As part of a larger effort between the U.S. Geological Survey (USGS) Ecosystems Mission Area and the Service’s endangered species program, we are also collaborating to address science needs for species in pre-listing status. Barry Grand, Unit Supervisor (South), has been instrumental in this effort. Tom Edwards of the Utah Unit has met with representatives of the U.S. Fish and Wildlife Service and the Association of Fish and Wildlife Agencies to promote training of leaders and “hands dirty” biologists in species distribution modeling. The Association passed a unanimous resolution endorsing the training at their midyear meeting in March. Tom held a workshop at the annual meeting of the Association of Fish and Wildlife Agencies in September, and future workshops, supported by the U.S. Fish and Wildlife Service, will be held bringing State agency and U.S. Fish and Wildlife Service biologists together to work on species of common concern. Wyoming Unit Leader Matt Kauffman’s pioneering work in identifying and mapping big-game migration corridors has captured the attention of conservationists far and wide. In the spring, the Secretary of the Interior signed Secretarial Order No. 3362, "Improving Habitat Quality in Western Big-Game Winter Range and Migration Corridors" directing efforts of several U.S. Department of the Interior (DOI) bureaus to collaborate with States in identifying and protecting big-game corridors in 11 States. Matt has conducted several workshops that directly support the Secretarial order, and more are planned. Corridor mapping efforts supported by the USGS and the DOI, based in the States and coordinated by Matt, are unfolding. Unit Administrative Officer Shana Coulby and her staff hosted a training program for university support staff at USGS National Headquarters in March. Shana’s team did a superb job, and the camaraderie among all was evident. We co-sponsored the third in a series of workshops at the North American Wildlife and Natural Resources Conference in March on bridging the gap between science and management. The State Department requested that we coordinate a workshop that would bring CRU scientists and other U.S. representatives together with Brazilian, Colombian, and Peruvian scientists and decision makers to develop best practices to minimize environmental damage from infrastructure development in the Amazon and to collaborate on science needs. The workshop was held in Iquitos, Peru, in the heart of the Amazon during August. Our cooperator community, represented by the National Cooperators Coalition, was very active in response to the President’s budget proposal that would have redirected funding for the CRU program to other priorities. Their efforts are reflected in the House and Senate marks on the fiscal year 2019 budget that not only restored funding, but recommended increases. You will see in this report many other accomplishments of our individual scientists and students during 2018. It was an impressive and productive year! What you won’t see chronicled is the work of the CRU headquarters staff and University support staff. These folks are extraordinary in their dedication to working with cooperators and scientists to solve problems and ensure the important work gets accomplished with minimal interference. We are truly fortunate to have such skilled and dedicated folks in the trenches. I was fortunate to visit several units during 2018. For me, this is the most enriching part of my duties. I get to see firsthand the work our scientists do, the incredible students being mentored, and meet our cooperators on their turf. As we look forward towards the horizon, 2019 looks brighter for the CRU program. Efforts by our cooperators to generate support for filling our vacancies are materializing. Our cadre of scientists is second to none, and the breadth and depth of our work are nothing short of impressive. Thanks to all who are part of this cooperative endeavor—conservation is the ultimate winner in our efforts!

Circular↗

USGS2007

Analysis of the sea otter ( Enhydra lutris ) reproductive tract: A methods manual

Reproduction in the female sea otter, Enhydra lutris, was relatively unstudied until Sinha et al. (1966) examined 140 reproductive tracts collected 1955-62 and used their findings to describe sea otter reproductive anatomy and biology. Two years later Sinha and Conaway (1968) published a more detailed paper on the ovary of the sea otter. These descriptive papers have been used as the basis for all subsequent studies of sea otter reproductive tracts. During biological collections of sea otters in the 1960s and 70s a large number of female carcasses became available to wildlife biologists. Using Sinha’s research, Schneider (1973) analyzed 1,482 female reproductive tracts to determine the timing of reproduction, gestation period, age of sexual maturity, fetal sex ratio and growth rate of otters in the Aleutian Islands. A similar study was conducted by Bodkin et al. (1993) on a sample of 177 females collected after the 1989 Exxon Valdez oil spill. Recently (von Biela 2007) examined 134 reproductive tracts obtained from beachcast and harvested otters across the three Alaskan population stocks as part of a Master’s thesis. As with most life history data, comparisons among and within populations that differ in status relative to equilibrium densities provide useful data with which to test hypotheses about the cause and effects of changes in demographic rates such as reproductive rate. However, in order to make such comparisons, methods used in different periods must be comparable. The purpose of this manual is to explicitly describe how to collect and analyze sea otter reproductive tracts for the determination of reproductive rate, pregnancy rate, percentage of mature females, and timing of reproduction so that the data will be directly comparable to that collected in the past. The techniques presented in this manual have been used to study sea otter populations over the last 50 years, and maintaining such consistency is essential to comparisons in the future. This manual is based on the methods of previous researchers and draws heavily on the published and unpublished works of James Bodkin, Karl Kenyon, Calvin Lensink, Daniel Mulcahy, Karl Schneider, and Akhouri Sinha. Most invaluable to the production of this manual were the direct communications with Karl Schneider and Dan Mulcahy. In each instance, researchers have communicated with each other to attain comparable methods. Recognizing that researchers in the future may not have this luxury, this guide has been produced to preserve the technique. In addition to using this manual, researchers should consult with colleagues experienced in the analysis of mammalian reproductive tracts, preferably specific to sea otters. Individuals are encouraged to contact V. von Biela with any questions. Sea otter reproductive tracts have most commonly come from either intentional sampling through harvests (Sinah et al. 1966, Schneider 1975) or unintentional large scale mortalities (e.g. the 1989 Exxon Valdez oil spill) (Bodkin et al. 1993). Carcasses and reproductive tracts can also be obtained through the collection of fresh beach cast carcasses. Analysis of reproductive tracts should consider the source of carcasses as samples representing either the “living” or “dead” sea otter population, as they may differ in reproductive parameters. In most cases the reproductive tracts are fixed in formalin or frozen (minimum of –20˚C) immediately after collection; both methods are acceptable for later analysis of the tissue. Immediate fixation is preferred as it is a necessary step in analysis. Uteri and ovaries are then examined to determine the current and past reproductive history of each individual. This manual also includes an example datasheet (Appendix A) and glossary (Appendix B).

Technical Report↗

USGS2008

Glaciers of North America - Glaciers of Alaska

Glaciers cover about 75,000 km 2 of Alaska, about 5 percent of the State. The glaciers are situated on 11 mountain ranges, 1 large island, an island chain, and 1 archipelago and range in elevation from more than 6,000 m to below sea level. Alaska's glaciers extend geographically from the far southeast at lat 55 deg 19'N., long 130 deg 05'W., about 100 kilometers east of Ketchikan, to the far southwest at Kiska Island at lat 52 deg 05'N., long 177 deg 35'E., in the Aleutian Islands, and as far north as lat 69 deg 20'N., long 143 deg 45'W., in the Brooks Range. During the 'Little Ice Age', Alaska's glaciers expanded significantly. The total area and volume of glaciers in Alaska continue to decrease, as they have been doing since the 18th century. Of the 153 1:250,000-scale topographic maps that cover the State of Alaska, 63 sheets show glaciers. Although the number of extant glaciers has never been systematically counted and is thus unknown, the total probably is greater than 100,000. Only about 600 glaciers (about 1 percent) have been officially named by the U.S. Board on Geographic Names (BGN). There are about 60 active and former tidewater glaciers in Alaska. Within the glacierized mountain ranges of southeastern Alaska and western Canada, 205 glaciers (75 percent in Alaska) have a history of surging. In the same region, at least 53 present and 7 former large ice-dammed lakes have produced jokulhlaups (glacier-outburst floods). Ice-capped volcanoes on mainland Alaska and in the Aleutian Islands have a potential for jokulhlaups caused by subglacier volcanic and geothermal activity. Because of the size of the area covered by glaciers and the lack of large-scale maps of the glacierized areas, satellite imagery and other satellite remote-sensing data are the only practical means of monitoring regional changes in the area and volume of Alaska's glaciers in response to short- and long-term changes in the maritime and continental climates of the State. A review of the literature for each of the 11 mountain ranges, the large island, the island chain, and the archipelago was conducted to determine both the individual and the regional status of Alaskan glaciers and to characterize changes in thickness and terminus position of representative glaciers in each mountain range or island group. In many areas, observations used for determining changes date from the late 18th or early 19th century. Temperature records at all Alaskan meteorological recording stations document a 20th century warming trend. Therefore, characterizing the response of Alaska's glaciers to changing climate helps to quantify potential sea-level rise from past, present, and future melting of glacier ice (deglaciation of the 14 glacierized regions of Alaska), understand present and future hydrological changes, and define impacts on ecosystems that are responding to deglacierization. Many different types of data were scrutinized to determine baselines and to assess the magnitude of glacier change. These data include the following: published descriptions of glaciers (1794-2000), especially the comprehensive research by Field (1975a) and his colleagues in the Alaska part of Mountain Glaciers of the Northern Hemisphere, aerial photography (since 1926), ground photography (since 1884), airborne radar (1981-91), satellite radar (1978-98), space photography (1984-94), multispectral satellite imagery (since 1972), aerial reconnaissance and field observations made by many scientists during the past several decades, and various types of proxy data. The published and unpublished data available for each glacierized region and individual glacier varied significantly. Geospatial analysis of digitized U.S. Geological Survey (USGS) topographic maps is used to statistically define selected glaciological parameters in the eastern part of the Alaska Range. The analysis determined that every mountain range and island group investigated can be characterized by significant glacier retreat, thinning, and (or) stagnation, especially those glaciers that end at lower elevations. At some locations, glaciers completely disappeared during the 20th century. In other areas, retreat that started as early as the early 18th century has continued into the 21st century. Ironically, in several areas, retreat is resulting in an increase in the total number of glaciers; even though individual glaciers are separating, the volume and area of ice continue to decrease.

Alaska↗

USGS2010

A Natural History Summary and Survey Protocol for the Southwestern Willow Flycatcher

The Southwestern Willow Flycatcher (Empidonax traillii extimus) has been the subject of substantial research, monitoring, and management activity since it was listed as an endangered species in 1995. When proposed for listing in 1993, relatively little was known about the flycatcher's natural history, and there were only 30 known breeding sites supporting an estimated 111 territories rangewide (Sogge and others, 2003a). Since that time, thousands of presence/absences surveys have been conducted throughout the historical range of the flycatcher, and many studies of its natural history and ecology have been completed. As a result, the ecology of the flycatcher is much better understood than it was just over a decade ago. In addition, we have learned that the current status of the flycatcher is better than originally thought: as of 2007, the population was estimated at approximately 1,300 territories distributed among approximately 280 breeding sites (Durst and others, 2008a). Concern about the Southwestern Willow Flycatcher on a rangewide scale was brought to focus by Unitt (1987), who described declines in flycatcher abundance and distribution throughout the Southwest. E. t. extimus populations declined during the 20th century, primarily because of habitat loss and modification from activities, such as dam construction and operation, groundwater pumping, water diversions, and flood control. In 1991, the U.S. Fish and Wildlife Service (USFWS) designated the Southwestern Willow Flycatcher as a candidate category 1 species (U.S. Fish and Wildlife Service, 1991). In July 1993, the USFWS proposed to list E. t. extimus as an endangered species and to designate critical habitat under the Act (U.S. Fish and Wildlife Service, 1993). A final rule listing E. t. extimus as endangered was published in February 1995 (U.S. Fish and Wildlife Service, 1995); critical habitat was designated in 1997 (U.S. Fish and Wildlife Service, 1997). The USFWS Service released a Recovery Plan for the Southwestern Willow Flycatcher in 2002 (U.S. Fish and Wildlife Service, 2002), and re-designated critical habitat in 2005 (U.S. Fish and Wildlife Service, 2005).

Techniques and Methods↗

USGS2016

Ciscoes ( Coregonus , subgenus Leucichthys ) of the Laurentian Great Lakes and Lake Nipigon

This study of the ciscoes ( Coregonus , subgenus Leucichthys ) of the Great Lakes and Lake Nipigon represents a furtherance through 2015 of field research initiated by Walter Koelz in 1917 and continued by Stanford Smith in the mid-1900s—a period spanning nearly a century. Like Koelz’s study, this work contains information on taxonomy, geographical distribution, ecology, and status of species (here considered forms). Of the seven currently recognized forms ( C. artedi , C. hoyi , C. johannae , C. kiyi , C. nigripinnis , C. reighardi , and C. zenithicus ) described by Koelz as major in his 1929 monograph, two ( C. johannae and C. reighardi ) are extinct. In addition, C. alpenae , described by Koelz but subsequently synonymized with C. zenithicus , although extinct, is recognized as valid making a total of eight major forms. Six of these forms, all but C. artedi and C. hoyi , have been lost from Lake Michigan, and seven have been lost from Lake Huron, leaving in Lake Huron only C. artedi and an introgressed deepwater form that we term a hybrid swarm. C. artedi appears, like its sister form C. alpenae , to have been lost from Lake Erie. Only C. artedi remains extant in Lake Ontario, its three sister forms ( C. hoyi , C. kiyi , and C. reighardi ) having disappeared long ago. Lakes Superior and Nipigon have retained their original species flocks consisting of four forms each: C. artedi , C. hoyi , and C. zenithicus in both lakes; C. kiyi in Lake Superior; and C. nigripinnis in Lake Nipigon. Morphological deviations from the morphotypes described by Koelz have been modest in contemporary samples. Overall, C. kiyi and C. artedi were the most morphologically stable forms while C. hoyi , C. nigripinnis , and C. zenithicus were the least stable. Although contemporary populations of C. artedi from Lakes Michigan and Huron are highly diverged from the morphotypes described by Koelz, the contemporary samples were of undescribed deep-bodied forms unlikely to have been sampled by Koelz because of their association with bays. Of the two intact species flocks, Lake Nipigon’s was much less stable morphologically than Lake Superior’s even though Lake Nipigon is far less disturbed. Two priorities for research are determining the role of developmental plasticity in morphological divergence, especially within C. zenithicus of Lake Superior, and the basis for morphological divergence in C. artedi .

Lake Nipigon, Laurentian Great Lakes↗

USGS2015

Status and trends of land change in the Midwest–South Central United States—1973 to 2000

U.S. Geological Survey (USGS) Professional Paper 1794–C is the third in a four-volume series on the status and trends of the Nation’s land use and land cover, providing an assessment of the rates and causes of land-use and land-cover change in the Midwest–South Central United States between 1973 and 2000. Volumes A, B, and D provide similar analyses for the Western United States, the Great Plains of the United States, and the Eastern United States, respectively. The assessments of land-use and land-cover trends are conducted on an ecoregion-by-ecoregion basis, and each ecoregion assessment is guided by a nationally consistent study design that includes mapping, statistical methods, field studies, and analysis. Individual assessments provide a picture of the characteristics of land change occurring in a given ecoregion; in combination, they provide a framework for understanding the complex national mosaic of change and also the causes and consequences of change. Thus, each volume in this series provides a regional assessment of how (and how fast) land use and land cover are changing, and why. The four volumes together form the first comprehensive picture of land change across the Nation. Geographic understanding of land-use and land-cover change is directly relevant to a wide variety of stakeholders, including land and resource managers, policymakers, and scientists. The chapters in this volume present brief summaries of the patterns and rates of land change observed in each ecoregion in the Midwest–South Central United States, together with field photographs, statistics, and comparisons with other assessments. In addition, a synthesis chapter summarizes the scope of land change observed across the entire Midwest–South Central United States. The studies provide a way of integrating information across the landscape, and they form a critical component in the efforts to understand how land use and land cover affect important issues such as the provision of ecological goods and services and also the determination of risks to, and vulnerabilities of, human communities. Results from this project also are published in peer-reviewed journals, and they are further used to produce maps of change and other tools for land management, as well as to provide inputs for carbon-cycle modeling and other climate change research.

Professional Paper↗

USGS2016

Proceedings of the 2015 international summit on fibropapillomatosis: Global status, trends, and population impacts

The 2015 International Summit on Fibropapillomatosis (FP) was convened in Honolulu, Hawaii June 11-14, 2015. Scientists from around the world were invited to present results from sea turtle monitoring and research programs as they relate to the global status, trends, and population impacts of FP on green turtles. The participants engaged in discussions that resulted in the following conclusions: 1.Globally, FP has long been present in wild sea turtle populations the earliest mention was in the late 1800s in the Florida Keys. 2.FP primarily affects medium-sized immature turtles in coastal foraging pastures. 3.Expression of FP differs across ocean basins and to some degree within basins. Turtles in the Southeast US, Caribbean, Brazil, and Australia rarely have oral tumors (inside the mouth cavity), whereas they are common and often severe in Hawaii. Internal tumors (on vital organs) occur in the Atlantic and Hawaii, but only rarely in Australia. Liver tumors are common in Florida but not in Hawaii. 4.Recovery from FP through natural processes, when the affliction is not severe, has been documented in wild populations globally. 5.FP causes reduced survivorship, but documented mortality rates in Australia and Hawaii are low. The mortality impact of FP is not currently exceeding population growth rates in some intensively monitored populations (e.g., Florida, Hawaii) as evidenced by increasing nesting trends despite the incidence of FP in immature foraging populations. 6.Pathogens, hosts, and potential disease and environmental cofactors have the capacity to change; while we are having success now, there needs to be continued monitoring to detect changes in the distribution, occurrence, and severity of the disease. 7.While we do not have clear evidence to provide the direct link, globally, the preponderance of sites with a high frequency of FP tumors are areas with some degree of degradation resulting from altered watersheds. Watershed management and responsible coastal development may be the best approach for reducing the spread and prevalence of the disease. 8.Future research efforts should employ a multi-factorial ecological approach (e.g., virology, parasitology, genetics, health, diet, habitat use, water quality, etc.) since there are likely several environmental cofactors involved in the expression of the disease, which is still thought to be caused by a herpesvirus. 9.Minimum FP data collection in new areas should include: individual identification (photo ID, PIT tags, etc.), standard measurements (length and weight), presence/absence of tumors, tumor severity, body condition, oral examination, method of capture, and effort

NOAA Technical Memorandum↗

USGS2024

Snake River Fall Chinook Salmon research and monitoring

In Chapter 1, we report on development and application of an integrated population model (IPM) for the natural-origin fall Chinook salmon population upstream of Lower Granite Dam. This year’s efforts represent the third update to the model. Initial efforts focused on generating juvenile and adult abundance estimates, with estimates of uncertainty, for informing the life-cycle model and estimating the effects of covariates on key demographic parameters. The goals of this year’s report are to 1) describe the modifications and advances made since the previous report, 2) to annually update and report the abundance estimates and other quantities used in the model, 3) to provide annual estimates of population parameters estimated by the IPM, and 4) to outline the next year’s tasks for advancing and/or applying the model. Since our last report on the life-cycle model, we have made a number of changes including: 1) incorporating jack abundance and age-structure data into the observation model, 2) changing smolt-to-adult survival (SAR) for subyearling and yearling to partial SARs that represent the joint probability surviving and entering the ocean at a given juvenile age, 3) combining age categories for rarely observed ages, 4) using scale data from unmarked fish to estimate age structure, and 5) generating composite life-cycle demographic parameters (cumulative capacity and productivity) from stage-specific parameters. We also generated juvenile abundance estimates, extended the model to include three additional brood years (1992– 2021), and ran the model to forecast returns to Lower Granite in 2022. For posterior medians of life stage-specific parameters, we estimated a mean productivity of 438 natural-origin juvenile recruits per female spawner, a capacity of 1.36 million juveniles, and a mean smolt-to-adult survival (SAR) of 1.2%. We detected strong density-dependent regulation, with juvenile recruits per spawner declining to about 50 juvenile recruits per female spawner at high spawner abundance. Across the entire life cycle, these stage-specific parameters resulted in a median cumulative intrinsic productivity of 1.93 adult female recruits per female spawner and a median equilibrium abundance of 2,851 female spawners (7,842 total spawners). Annual juvenile productivity varied from about 250–1,000 juveniles per spawner but displayed no temporal trends or patterns. For the three most recent brood years added to the model, recruits per spawner were higher than average but well within the range of uncertainty observed over the entire time series. In contrast to juvenile recruitment variability, SAR varied considerably among years and exhibited two periods of high survival (1996–2001 and 2007–2012) when SAR ranged from 2% to 6% and cumulative productivity ranged from 2 to 8 recruits per spawner. Partial SARs revealed that yearling outmigrants contributed substantially to the high SARs in the first high-survival period, but the second period was dominated by subyearlings. Yearlings contributed >30% to SAR in most years prior to 2007, and <30% since 2007. Our two-stage IPM provides a wealth of information about population dynamics affecting two key life-stage transitions (spawner to juvenile, and juvenile to spawner) centered on passage at Lower Granite Dam. By summarizing these stage-specific demographic parameters across the entire life cycle, this information will be useful for informing the recovery status of this threatened population. Whereas previous versions introduced hydrosystem and ocean covariates into the model, this phase of model development focused on solidifying the underlying model structure by introducing the concept of partial SARs and developing composite productivity and capacity as a function of underlying stage-specific parameters. Given this advancement, our next steps are to re-incorporate covariates into the model, specifically to understand how different factors affect partial SARs of subyearling and yearlings. Longer term model developments include:1) incorporating hatchery fish to explicitly estimate their survival as an alternative method for estimating natural-origin age composition, 2) expanding the model’s structure to include the three major spawning aggregates, 3) more explicitly modeling hydrosystem effects including transportation, and 4) using the model to assess retrospective and prospective management actions. In 2022, the U.S. Geological Survey (USGS) focused adult salmon survey efforts in the Snake River on deepwater redd searches and fish collection for parentage-based tagging (PBT) analyses. We use used a boat-mounted underwater video camera to count 99 deepwater redds at 16 of the 29 sites surveyed. Redd depths averaged 4.4 m. In conjunction with the Idaho Power Company, we collected genetic samples from 318 live fall Chinook salmon (Oncorhynchus tshawytscha) and 19 carcasses at 40 unique geographic locations that spanned 91 river kilometers. Eighty fish were collected at three sites (High Range [rkm 332.3], Dug Bar [rkm 315.4], and Three Creek [rkm 384.0]), which accounted for 23% of all collected fish in 2022. Most (333 fish) post-spawned salmon were collected from early to mid-November just after the peak of spawning. A summary of 2021 PBT results produced by the Idaho Power Company can be found in Appendix A.2. Beach seining and PIT tagging of subyearling fall Chinook salmon was conducted in Snake and Salmon rivers to obtain information on population metrics and growth as well as to provide data for ongoing life-cycle modeling. In the Snake River, we collected 7,496 subyearlings, tagged 4,139, and recaptured 502 (12.1%). Using 8-mm tags in 45–49-mm fish allowed us to represent an additional 25% of the juvenile population through PIT tagging beyond just using standard 9- and 12-mm tags. In the Salmon River, we captured 206 natural subyearlings with the majority (52%) of fish being captured at two sites: rkm 20 and 26. We tagged 145 subyearlings and recaptured 9 fish. Many of the subyearlings we tagged in the Snake River were detected passing Lower Granite Dam, but only 4 fish tagged in the Salmon River were detected. In total we detected 484 (11.3%) tagged fish at Lower Granite Dam, and detection rates varied by tag size and passage route. More subyearlings were detected passing via the removable spill weir (RSW) earlier in the season while more fish were detected passing through the juvenile fish bypass system (JBS) earlier in the season while more fish were detected passing via the removable spill weir (RSW) later in the season. In general, fish tagged with 12-mm PIT tags had higher detection rates than fish tagged with smaller tags. Survival to Lower Granite Dam was low and ranged from 0.22 to 0.36. Season-wide, growth of subyearlings was higher in the lower reach than in the upper reach of the Snake River.

Idaho, Oregon, Washington↗

USGS2007

Ohio Aquatic Gap Analysis-An Assessment of the Biodiversity and Conservation Status of Native Aquatic Animal Species

The goal of the GAP Analysis Program is to keep common species common by identifying those species and habitats that are not yet adequately represented in the existing matrix of conservation lands. The Gap Analysis Program (GAP) is sponsored by the Biological Resources Discipline of the U.S. Geological Survey (USGS). The Ohio Aquatic GAP (OH-GAP) is a pilot project that is applying the GAP concept to aquatic-specifically, riverine-data. The mission of GAP is to provide regional assessments of the conservation status of native animal species and to facilitate the application of this information to land-management activities. OH-GAP accomplished this through * mapping aquatic habitat types, * mapping the predicted distributions of fish, crayfish, and bivalves, * documenting the presence of aquatic species in areas managed for conservation, * providing GAP results to the public, planners, managers, policy makers, and researchers, and * building cooperation with multiple organizations to apply GAP results to state and regional management activities. Gap analysis is a coarse-scale assessment of aquatic biodiversity and conservation; the goal is to identify gaps in the conservation of native aquatic species. It is not a substitute for biological field studies and monitoring programs. Gap analysis was conducted for the continuously flowing streams in Ohio. Lakes, reservoirs, wetlands, and the Lake Erie islands were not included in this analysis. The streams in Ohio are in the Lake Erie and Ohio River watersheds and pass through six of the level III ecoregions defined by Omernik: the Eastern Corn Belt Plains, Southern Michigan/Northern Indiana Drift Plains, Huron/Erie Lake Plain, Erie Drift Plains, Interior Plateau, and the Western Allegheny Plateau. To characterize the aquatic habitats available to Ohio fish, crayfish, and bivalves, a classification system needed to be developed and mapped. The process of classification includes delineation of areas of relative homogeneity and labeling these areas using categories defined by the classification system. The variables were linked to the 1:100,000-scale streams of the National Hydrography Dataset of the USGS. Through discussions with Ohio aquatic experts, OH-GAP identified eight separate enduring physical features which, when combined, form the physical habitat type: * Shreve link (a measure of stream size) * Downstream Shreve link (a measure of stream connectivity and size) * Sinuosity * Gradient * Bedrock * Stream temperature * Character of glacial drift * Glacial-drift thickness Potential distribution models were developed for 130 fish, 70 bivalve, and 17 native crayfish species. These models are based on 5,686 fish, 4,469 crayfish, and 2,899 freshwater bivalve (mussels and clams) sampling locations, the variables describing the physical habitat types, and variables indicating the major drainage basins and Omernik's Level III ecoregion. All potential species distributions are displayed and analyzed at the 14-digit hydrologic unit (14-HUs), or subwatershed, level. Mainland Ohio contains 1,749 14-HUs. All statistics and conclusions, as well as spatial data, are discussed and presented in terms of these units. The Ohio Aquatic Gap Analysis Project compiled a map of public and private conservation lands and OH-GAP classified the lands into four status categories (status 1 through status 4) by the degree of protection offered based on management practices. A status of 1 denotes the highest, most permanent level of maintenance, and status 4 represents the lowest level of biodiversity management, or unknown status. The results of this mapping show that only about 3.7 percent of the state's land (4.3 percent if lakes and reservoirs are also included) is protected for conservation, either publicly or privately. Of this total, state agencies control about 52 percent, and Federal agencies control about 29 percent. Conservation areas that presently protect

Open-File Report↗

USGS2023

Southern (California) sea otter population status and trends at San Nicolas Island, 2020–2023

The population of southern sea otters ( Enhydra lutris nereis ) at San Nicolas Island, California, has been monitored annually since the translocation of 140 southern sea otters to the island was completed in 1990. Monitoring efforts have varied in frequency and type across years. In 2017, the U.S. Navy and the U.S. Fish and Wildlife Service initiated a southern sea otter monitoring and research plan to determine the effects of military readiness activities on the growth or decline of the southern sea otter population at San Nicolas Island. The southern sea otter is the only subspecies of sea otter in California (hereafter, “sea otter"). The monitoring program, at its basic level, includes seasonal surveys of population abundance, distribution, and foraging activity. From 2020 to 2023, we measured a 10-percent per annum increase in population abundance (95-percent confidence interval =0–20 percent), with 146 total individuals as of April 2023. Coinciding with the recent population growth, the sea otter distribution, which previously tended to concentrate on the island’s west end during 2003–2006 before shifting toward more use in the north and south sides during 2017–2019, appears to have shifted again during 2020–2023 to concentrate at the island’s east end. Forage data were collected between February 2020 and April 2023. There was a total of 773 forage dives in 60 forage bouts, with most of the identified prey on successful dives (n=401) recorded as sea urchins (66 percent), followed by bivalves (15 percent), snails (12 percent), and crabs (5.2 percent). Two lobsters and three abalone also were identified among the sea otter prey. Estimates of energy intake rates averaged 14.0 kilocalories per minute (95-percent confidence interval =10.8–17.2 kilocalories per minute). Monitoring data from the past two decades indicate that sea otters at San Nicolas Island have maintained a steady pattern of energy intake and population growth characteristic of a robust population, including a sixfold growth between 2000 and 2023. There was no conclusive evidence of density-dependent effects based on these patterns; however, estimates of energy intake rates for 2020–2023 were slightly lower than previous estimates from 2017 to 2019. Additionally, subtidal monitoring results at four sites around San Nicolas Island indicated that counts of purple sea urchins ( Strongylocentrotus purpuratus ) have increased between 2003 and 2023, whereas sea otter foraging surveys completed during the same period revealed that some sea otters have shifted toward higher consumption of purple sea urchins and bivalves compared to red sea urchins ( S. fransicanus ), which generally are the preferred larger prey of sea otters. These results contribute to the understanding of population dynamics and to the conservation and planning of future monitoring and research of sea otters at San Nicolas Island.

California↗

USGS2014

Hydrogeology of the Old Faithful area, Yellowstone National Park, Wyoming, and its relevance to natural resources and infrastructure

A panel of leading experts (The Old Faithful Science Review Panel) was convened by Yellowstone National Park (YNP) to review and summarize the geological and hydrological understanding that can inform National Park Service management of the Upper Geyser Basin area. We give an overview of present geological and hydrological knowledge of the Old Faithful hydrothermal (hot water) system and related thermal areas in the Upper Geyser Basin. We prioritize avenues for improving our understanding of key knowledge gaps that limit informed decision-making regarding human use in this fragile natural landscape. Lastly, we offer guidelines to minimize impacts to the hydrothermal system that could be used to aid decisions by park management. Old Faithful sits within the Upper Geyser Basin, an area of abundant hydrothermal activity where boiling waters extend from the surface to significant depth within glacial sediments and underlying volcanic rocks. The geyser systems are directly fed by waters recharged decades to millennia ago, which are surrounded by colder, younger waters. Activity of the geysers is controlled by complex subsurface plumbing with fractures and conduits separated by regions of low permeability. Observations over the past century indicate that the thermal areas and their features are both fragile and highly dynamic. Although Old Faithful has erupted regularly for the past 150 years, it exhibits changes in eruptive behavior over time, and the average interval between eruptions has increased by about 50 percent over the past 50 years. It is clear that human activity has modified the hydrothermal system in the past; conversely, natural features pose ongoing hazards to humans and human infrastructure. Current (2014) long-term programs to measure heat discharge by chloride-flux monitoring, and more recently by thermal-infrared imaging, are crucial for assessing the status of the hydrothermal system. Complementary studies could include airborne resistivity, environmental tracers, numerical modeling, and greater emphasis on measuring the discharge of water during geyser eruptions. Such data are needed to better understand the subsurface plumbing systems that feed the geysers. Further understanding can be gained through installation of shallow groundwater observation wells, surface geophysical studies, and direct measurement of temperature gradients near the surface. It also is critical to archive existing data from all studies in a manner that will be readily accessible to scientists and decision makers. Monitoring and data collection can be achieved through the YNP geology program, by direct funding to other groups, or by encouraging and facilitating externally funded research. There are many documented examples at YNP and elsewhere where human infrastructure and natural thermal features have negatively affected each other. Unless action is taken, human conflicts with the Old Faithful hydrothermal system are likely to increase over the coming years. This is partly because of the increase in park visitation over the past decades, but also because the interval between eruptions of Old Faithful has increased, lengthening the time spent (and services needed) for each visitor at Old Faithful. To avoid an increase in visitor impacts, the National Park Service should consider 2 alternate strategies to accommodate people, vehicles, and services in the Upper Geyser Basin, such as shuttle services from staging (parking and dining) areas with little or no recent hydrothermal activity. We further suggest that YNP consider a zone system to guide maintenance and development of infrastructure in the immediate Old Faithful area. A “red” zone includes hydrothermally active land where new development is discouraged and existing infrastructure is modified with great care. An outer “green” zone represents areas where cooler temperatures and less hydrothermal flow are thought to exist, and where development and maintenance could proceed as occurs elsewhere in the park. An intermediate “yellow” zone would require preliminary assessment of subsurface temperatures and gas concentrations to assess suitability for infrastructure development. The panel recommends that YNP management follow the lead of the National Park System Advisory Board Science Committee (2012) by applying the “precautionary principle” when making decisions regarding the interaction of hydrothermal phenomena and park infrastructure in the Old Faithful area and other thermal areas within YNP.

Wyoming↗

USGS2014

2013 update on sea otter studies to assess recovery from the 1989 Exxon Valdez oil spill, Prince William Sound, Alaska

On March 24, 1989, the tanker vessel Exxon Valdez ran aground in Prince William Sound, Alaska, spilling an estimated 42 million liters of Prudhoe Bay crude oil. Oil spread in a southwesterly direction and was deposited on shores and waters in western Prince William Sound (WPWS). The sea otter (Enhydra lutris) was one of more than 20 nearshore species considered to have been injured by the spill. Since 1989, the U.S. Geological Survey has led a research program to evaluate effects of the spill on sea otters and assess progress toward recovery, as defined by demographic and biochemical indicators. Here, we provide an update on the status of sea otter populations in WPWS, presenting findings through 2013. To assess recovery based on demographic indicators, we used aerial surveys to estimate abundance and annual collections of sea otter carcasses to evaluate patterns in ages-at-death. To assess recovery based on biochemical indicators, we quantified transcription rates for a suite of genes selected as potential indicators of oil exposure in sea otters based on laboratory studies of a related species, the mink (Mustela vison). In our most recent assessment of sea otter recovery, which incorporated results from a subset of studies through 2009, we concluded that recovery of sea otters in WPWS was underway. This conclusion was based on increasing abundance throughout WPWS, including increasing numbers at northern Knight Island, an area that was heavily oiled in 1989 and where the local sea otter population had previously shown protracted injury and lack of recovery. However, we did not conclude that the WPWS sea otter population had fully recovered, due to indications of continuing reduced survival and exposure to lingering oil in sea otters at Knight Island, at least through 2009. Based on data available through 2013, we now conclude that the status of sea otters—at all spatial scales within WPWS—is consistent with the designation of recovery from the spill as defined by the Exxon Valdez Oil Spill Trustee Council. The support for this conclusion is based primarily on demographic data, including (1) a return to estimated pre-spill abundance of sea otters at northern Knight Island, and (2) a return to pre-spill mortality patterns. Gene transcription rates in 2012 were similar in sea otters from oiled, moderately oiled and unoiled areas, suggesting abatement of exposure effects in 2012. However, because 2012 gene transcription rates generally were low for sea otters from all areas relative to 2008, we cannot fully interpret these observations without data from a wider panel of genes. This slight uncertainty with respect to the data from the biochemical indicator is outweighed by the strength of the data for the demographic indicators. The return to pre-spill numbers and mortality patterns suggests a gradual dissipation of lingering oil over the past two decades, to the point where continuing exposure is no longer of biological significance to the WPWS sea otter population.

Alaska↗