SEARCH · USGS Science

Results for “Fisheries”

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 1,567 records · Page 87Linked to original sources

USGS1992

Immunostimulants, adjuvants, and vaccine carriers in fish: Applications to aquaculture

Use of immunostimulants, adjuvants, and vaccine carriers in fish culture offers a wide range of attractive methods for inducing and building up protection against diseases. Immunostimulants and adjuvants can be administered before, with, or after vaccines to amplify the specific immune response generating elevations of circulating antibody titers and numbers of plaque-forming cells. Special applications of immunostimulants include assisting shower or other regimens to increase topical uptake of vaccines. In addition, immunostimulants may be used alone, inducing elevated activities in the nonspecific defense mechanisms such as increased oxidative activity of neutrophils, augmented engulfment activity of phagocytic cells, or potentiating cytotoxic cells. In cases where disease outbreaks are cyclical and can be predicted, losses may be reduced by elevating the nonspecific defense mechanisms, and the immunostimulants may be used in anticipation of events to prevent losses from diseases. Complete Freund's adjuvant was one of the first immunostimulants used in animals to elevate the specific immune response, and it has also been successfully used in conjunction with injection of fish bacterins. Other adjuvants, immunostimulants, and biological response modifiers that have been used in fisheries research include levamisole, salt baths, and bacterial lipopolysaccharides. Vaccines have been adsorbed to inert particles, such as bentonite on latex beads, to carry the immunogens to maximize in vivo uptake for bath immunization and to facilitate in vitro phagocytosis. Each substance presents special problems in timing and method of administration (injection, immersion, oral—by feed—or flush treatments), dosage adjustments for size and fish species, storage stability, and cost. An additional consideration is that the nonspecific defense mechanisms and immune responses in fish are highly variable among individuals and statistical validation requires appropriate sample numbers and carefully controlled experiments. This article reviews the literature and present concepts of use of immunostimulants, adjuvants, and vaccine carriers in fish. Cautions for use are noted, as some of these potent substances can suppress or alter biological pathways if used inappropriately. Recent research, defining pathways of the action of immunostimulants, adjuvants, and vaccine carriers, helps explain how these substances activate the protective mechanisms in fish. In addition, immunostimulants used alone hold tremendous potential for use in fish farms, hatcheries, and aquaculture facilities to reduce losses from infectious diseases. Research on the immunostimulant, levamisole, and the light oil adjuvants for use in food fish is in progress. Applications for use of these immunostimulants are proposed.

Annual Review of Fish Diseases↗

USGS1995

Viral hemorrhagic septicemia virus in North America

The first detections of viral hemorrhagic septicemia virus (VHSV) in North America were in Washington State from adult coho ( Oncorhynchus kisutch ) and chinook ( O. tshawytscha ) salmon in 1988. Subsequently, VHSV was isolated from adult coho salmon returning to hatcheries in the Pacific Northwest in 1989, 1991 and 1994. These isolates represented a strain of VHSV that was genetically different from European VHSV as determined by DNA sequence analysis and T1 ribonuclease fingerprinting. The North American strain of VHSV was also isolated from skin lesions of Pacific cod ( Gadus macrocephalus ) taken from Prince William Sound (PWS), Alaska in 1990, 1991 and 1993. In 1993 and 1994, the virus was isolated from Pacific herring ( Clupea harengus pallasi ) in Alaskan waters of PWS, Kodiak Island, Auke Bay and Port Frederick. During 1993 and 1994 the herring fishery in PWS failed from a probable complex of environmental stressors but VHSV isolates were associated with hemorrhages of the skin and fins in fish that returned to spawn. Also in 1993 and 1994, VHSV was isolated from apparently healthy stocks of herring in British Columbia, Canada and Puget Sound, Washington. Thus, the North American strain of VHSV is enzootic in the Northeastern Pacific Ocean among Pacific herring stocks with Pacific cod serving as a secondary reservoir. Although the North American strain of the virus appears to be moderately pathogenic for herring, causing occasional self-limiting epizootics, it was shown to be relatively avirulent for several species of salmonids. Pacific herring are common prey for cod and salmon and were most probably the source of the VHSV isolates from the adult salmon returning to spawn in rivers or at hatcheries in Washington State. Compelling circumstances involving the European isolates of VHSV suggest that this strain of the virus also is enzootic among marine fish in the Atlantic Oean. The highly pathogenic nature of the European strain of VHSV for salmonid fish may be the result of the exposure of rainbow trout ( O. mykiss ), an introduced species, in a stressful environment of intensive culture and the high rate of mutation inherent in all rhabdoviruses. Consequently, we recommend that efforts be made to eradicate the North American strain of VHSV when detected in live salmonids to reduce the possibility of its evolution into a more virulent salmonid virus.

Annual Review of Fish Diseases↗

USGS1993

Geological and technological assessment of artificial reef sites, Louisiana outer continental shelf

This paper describes the general procedures used to select sites for obsolete oil and gas platforms as artificial reefs on the Louisiana outer continental shelf (OCS). The methods employed incorporate six basic steps designed to resolve multiple-use conflicts that might otherwise arise with daily industry and commercial fishery operations, and to identify and assess both geological and technological constraints that could affect placement of the structures. These steps include: (1) exclusion mapping; (2) establishment of artificial reef planning areas; (3) database compilation; (4) assessment and interpretation of database; (5) mapping of geological and man-made features within each proposed reef site; and (6) site selection. Nautical charts, bathymetric maps, and offshore oil and gas maps were used for exclusion mapping, and to select nine regional planning areas. Pipeline maps were acquired from federal agencies and private industry to determine their general locations within each planning area, and to establish exclusion fairways along each pipeline route. Approximately 1600 line kilometers of high-resolution geophysical data collected by federal agencies and private industry was acquired for the nine planning areas. These data were interpreted to determine the nature and extent of near-surface geologic features that could affect placement of the structures. Seismic reflection patterns were also characterized to evaluate near-bottom sedimentation processes in the vicinity of each reef site. Geotechnical borings were used to determine the lithological and physical properties of the sediment, and for correlation with the geophysical data. Since 1987, five sites containing 10 obsolete production platforms have been selected on the Louisiana OCS using these procedures. Industry participants have realized a total savings of approximately US $1 500 000 in salvaging costs by converting these structures into artificial reefs. ?? 1993.

Ocean and Coastal Management↗

USGS2011

Bioenergetics in ecosystems

A bioenergetics model for a fish can be defined as a quantitative description of the fish’s energy budget. Bioenergetics modeling can be applied to a fish population in a lake, river, or ocean to estimate the annual consumption of food by the fish population; such applications have proved to be useful in managing fisheries. In addition, bioenergetics models have been used to better understand fish growth and consumption in ecosystems, to determine the importance of the role of fish in cycling nutrients within ecosystems, and to identify the important factors regulating contaminant accumulation in fish from lakes, rivers, and oceans.

Book chapter↗

USGS2011

Swimming and other activities: applied aspects of fish swimming performance

Human activities such as hydropower development, water withdrawals, and commercial fisheries often put fish species at risk. Engineered solutions designed to protect species or their life stages are frequently based on assumptions about swimming performance and behaviors. In many cases, however, the appropriate data to support these designs are either unavailable or misapplied. This article provides an overview of the state of knowledge of fish swimming performance – where the data come from and how they are applied – identifying both gaps in knowledge and common errors in application, with guidance on how to avoid repeating mistakes, as well as suggestions for further study.

Book chapter↗

USGS2022

Applied aspects of locomotion and biomechanics

Locomotion is the act and process of moving from place to place, which is fundamental to the life history of all mobile organisms. While the field of biomechanics encompasses the study of the physical constraints of what animals are capable of, ecological contexts require an integrated view that includes ecology and behavior. This chapter provides an overview of some of the areas where locomotion and biomechanics of fish movement interface with the rapidly evolving changes that humans impose on aquatic environments. These changes include fundamental alterations to the environment such as altered flows, fragmentation of riverine habitats, and invasive species, but also direct interactions that occur with capture fisheries. We explore each of these areas, considering both challenges and opportunities informed by the study of locomotion and biomechanics, emphasizing how this field can contribute to conservation of fishes in the Anthropocene. We then turn to technology, where important advances are aiding in our understanding of fish movement. In some cases those advances have themselves led to novel technologies, where biomimetic robots and related devices offer novel opportunities, both for conservation and for other pursuits.

Book chapter↗

USGS2022

Invasive species control and management: The sea lamprey story

Control of invasive species is a critical component of conservation biology given the catastrophic damage that they can cause to the ecosystems they invade. This is particularly evident with sea lamprey ( Petromyzon marinus ) in the Laurentian Great Lakes. Native to the Atlantic Ocean, the sea lamprey's ability to osmoregulate in fresh water, its wide thermal tolerance, generalist diet, and high fecundity allowed it to rapidly reach pest proportions in the prey-rich Great Lakes once it gained access through shipping canals. The invasion exacerbated declines in Great Lakes fisheries caused by overharvest, culminating in the crash of lake trout ( Salvelinus namaycush ) and other fish populations. In the last 60 years, however, a highly successful sea lamprey control program has reduced sea lamprey to ∼10% of their peak abundance and has been instrumental in enabling the rehabilitation of the Great Lakes ecosystem. In this chapter, we: (1) discuss the likely vectors of the invasion and the physiological attributes of sea lamprey that enabled them to become established in the Great Lakes; (2) review the two cornerstones of the sea lamprey control program—which relies on a combination of pesticides to eradicate multiple generations of larval sea lamprey in their nursey streams, and in-stream barriers to restrict the upstream migration of spawning lamprey—both of which exploit unique physiological vulnerabilities of sea lamprey; (3) describe how sea lamprey control can adversely affect non-target species and how these can be mitigated; (4) show how physiology-based approaches are improving our understanding of the lethal and sublethal effects of sea lamprey on host fishes; and (5) discuss the future of conservation physiology in sea lamprey control. The prime challenge in the next several decades of the Anthropocene will be to further refine the specificity of control tools while maintaining their efficacy, and to adapt to a warming climate and other anthropogenic activities affecting the Great Lakes and their tributaries.

Lake Erie, Lake Huron, Lake Michigan, Lake Ontario↗

USGS2013

Large dams and alluvial rivers in the Anthropocene: The impacts of the Garrison and Oahe Dams on the Upper Missouri River

The Missouri River has had a long history of anthropogenic modification with considerable impacts on river and riparian ecology, form, and function. During the 20th century, several large dam-building efforts in the basin served the needs for irrigation, flood control, navigation, and the generation of hydroelectric power. The managed flow provided a range of uses, including recreation, fisheries, and habitat. Fifteen dams impound the main stem of the river, with hundreds more on tributaries. Though the effects of dams and reservoirs are well-documented, their impacts have been studied individually, with relatively little attention paid to their interaction along a river corridor. We examine the morphological and sedimentological changes in the Upper Missouri River between the Garrison Dam in ND (operational in 1953) and Oahe Dam in SD (operational in 1959). Through historical aerial photography, stream gage data, and cross sectional surveys, we demonstrate that the influence of the upstream dam is still a major control of river dynamics when the backwater effects of the downstream reservoir begin. In the “Anthropocene”, dams are ubiquitous on large rivers and often occur in series, similar to the Garrison Dam Segment. We propose a conceptual model of how interacting dams might affect river geomorphology, resulting in distinct and recognizable morphologic sequences that we term “Inter-Dam sequence” characteristic of major rivers in the US.

North Dakota;South Dakota;Wyoming↗

USGS2009

Depletion of isoeugenol residues from the fillet tissue of AQUI-S™ exposed rainbow trout ( Oncorhynchus mykiss )

There is a critical need in U.S. public aquaculture and fishery management for an approved sedative that allows for the immediate release of fish after sedation. AQUI-S TM is a fish anesthetic/sedative approved for use in several countries and until recently was being developed in the U.S. as a sedative for immediate release of fish after sedation. The U.S. National Toxicology Program reported that isoeugenol (the active ingredient in AQUI-S TM ) exposed male mice showed clear evidence of carcinogenicity, therefore efforts within the U.S. Department of Interior to develop AQUI-S TM as a sedative that allows for immediate release ceased. Despite the ruling, AQUI-S TM still has the potential to be approved as an anesthetic with a short withdrawal time. Among the data required to gain approval for use in the U.S. are data describing the composition and depletion of all AQUI-S TM residues from fish fillet tissue. A total residue depletion study for AQUI-S TM was conducted by exposing market-sized rainbow trout, Oncorhynchus mykiss (mean weight, 502.7 ± 54 g; s.d.) to 8.9 mg/L of 14 C-[URL]-isoeugenol for 60 min in 17 °C water. The 14 C-[URL]-isoeugenol was mixed with a surfactant resulting in a mixture that mimicked AQUI-S TM . Groups of fish ( n = 6) were sampled immediately after the exposure (0-h sample group) and at 0.5, 1, 2, and 4 h thereafter. Total isoeugenol-equivalent residue concentrations in the fillet tissue were determined by oxidizing triplicate subsamples of homogenized skin-on fillet tissue from each fish to 14 CO 2 and enumerating the radioactivity by static liquid scintillation counting. Isoeugenol concentrations in fillet tissue were determined by extracting homogenized fillet tissue with solvents and determining the isoeugenol concentrations in the extracts with high performance liquid chromatography techniques. The mean total isoeugenol-equivalent residue concentrations in the 0, 0.5, 1, 2, and 4-h sample groups were 55.4, 32.0, 19.8, 11.3, and 4.9 µg/g, respectively. The primary chemical residue in fillet tissue from all exposed fish was isoeugenol. The mean isoeugenol concentrations in the 0, 0.5, 1, 2, and 4-h sample groups were 48.9, 26.5, 15.3, 7.2, and 2.2 µg/g, respectively. The percents of the total radioactivity classified as isoeugenol in the 0, 0.5, 1, 2, and 4-h tissue extracts were 95, 73, 73, 64, and 48%, respectively.

Aquaculture↗

USGS2014

Evaluation of analytical techniques to determine AQUI-S® 20E (eugenol) concentrations in water

There is a critical need in U.S. public aquaculture and fishery management programs for an immediate-release sedative, i.e. a compound that can be safely and effectively used to sedate fish and subsequently, allow for their immediate release. AQUI-S® 20E (10% active ingredient, eugenol; any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government) is being pursued for U.S. approval as an immediate-release sedative. As part of the approval process, data describing animal safety and efficacy are needed. Essential to conducting studies that generate those data, is a method to accurately and precisely determine AQUI-S® 20E concentrations in exposure baths. Spectrophotometric and solid phase extraction (SPE)–high pressure liquid chromatography (LC) methods were developed and evaluated as methods to determine AQUI-S® 20E (eugenol) concentrations in water, methods that could be applied to any situation where eugenol was being evaluated as a fish sedative. The spectrophotometric method was accurate and precise (accuracy, > 87%; precision, < 0.70 %CV) when determining eugenol concentrations in solutions of 50 to 1000 mg/L AQUI-S® 20E made with LC grade water and water with varying pH and hardness. The spectrophotometric method's accuracy was negatively affected when analyzing water containing fish feed. The SPE–LC method was also accurate and precise (accuracy > 86%; precision < 8.9 %CV) when determining eugenol concentrations in solutions of 50 to 1000 mg/L AQUI-S® 20E made with LC grade water and water with varying pH and hardness. The SPE–LC method was influenced to a lesser degree by the presence of fish feed indicating greater specificity for eugenol.

Aquaculture↗

USGS2019

Control of invasive sea lampreys using the piscicides TFM and niclosamide: Toxicology, successes & future prospects

The invasion of the Laurentian Great Lakes of North America by sea lampreys ( Petromyzon marinus ) in the early 20th century contributed to the depletion of commercial, recreational and culturally important fish populations, devastating the economies of communities that relied on the fishery. Sea lamprey populations were subsequently controlled using an aggressive integrated pest-management program which employed barriers and traps to prevent sea lamprey from migrating to their spawning grounds and the use of the piscicides (lampricides) 3-trifluoromethyl-4-nitrophenol (TFM) and niclosamide to eliminate larval sea lampreys from their nursery streams. Although sea lampreys have not been eradicated from the Great Lakes, populations have been suppressed to less than 10% of their peak numbers in the mid-1900s. The ongoing use of lampricides provides the foundation for sea lamprey control in the Great Lakes, one of the most successful invasive species control programs in the world. Yet, significant gaps remain in our understanding of how lampricides are taken-up and handled by sea lampreys, how lampricides exert their toxic effects, and how they adversely affect non-target invertebrate and vertebrates species. In this review we examine what has been learned about the uptake, handling and elimination, and the mode of TFM and niclosamide toxicity in lampreys and in non-target animals, particularly in the last 10 years. It is now clear that the mode of TFM toxicity is the same in non-target fishes and lampreys, in which TFM interferes with oxidative phosphorylation by the mitochondria leading to decreased ATP production. Vulnerability to TFM is related to abiotic factors such as water pH and alkalinity, which we propose changes the relative amounts of the bioavailable un-ionized form of TFM in the gill microenvironment. Niclosamide, which is also a molluscicide used to control snails in areas prone to schistosomiasis infections of humans, also likely works by uncoupling oxidative phosphorylation, but less is known about other aspects of its toxicology. The effects of TFM include reductions in energy stores, particularly glycogen and high energy phosphagens. However, non-target fishes readily recover from sub-lethal TFM exposure as demonstrated by the rapid restoration of energy stores and clearance of TFM. Although both TFM and niclosamide are non-persistent in the environment and critical for sea lamprey control, increasing public and institutional concerns about pesticides in the environment makes it imperative to explore other means of sea lamprey control. Accordingly, we also address possible “next-generation” strategies of sea lamprey control including genetic tools such as RNA interference and CRISPR-Cas9 to impair critical physiological processes (e.g. reproduction, digestion, metamorphosis) in lamprey, and the use of green chemistry to develop more environmentally benign chemical methods of sea lamprey control.

Great Lakes↗

USGS2016

Response of fish assemblages to declining acidic deposition in Adirondack Mountain lakes, 1984–2012

Adverse effects of acidic deposition on the chemistry and fish communities were evident in Adirondack Mountain lakes during the 1980s and 1990s. Fish assemblages and water chemistry in 43 Adirondack Long-Term Monitoring (ALTM) lakes were sampled by the Adirondack Lakes Survey Corporation and the New York State Department of Environmental Conservation during three periods (1984–87, 1994–2005, and 2008–12) to document regional impacts and potential biological recovery associated with the 1990 amendments to the 1963 Clean Air Act (CAA). We assessed standardized data from 43 lakes sampled during the three periods to quantify the response of fish-community richness, total fish abundance, and brook trout ( Salvelinus fontinalis) abundance to declining acidity that resulted from changes in U.S. air-quality management between 1984 and 2012. During the 28-year period, mean acid neutralizing capacity (ANC) increased significantly from 3 to 30 μeq/L and mean inorganic monomeric Al concentrations decreased significantly from 2.22 to 0.66 μmol/L, yet mean species richness, all species or total catch per net night (CPNN), and brook trout CPNN did not change significantly in the 43 lakes. Regression analyses indicate that fishery metrics were not directly related to the degree of chemical recovery and that brook trout CPNN may actually have declined with increasing ANC. While the richness of fish communities increased with increasing ANC as anticipated in several Adirondack lakes, observed improvements in water quality associated with the CAA have generally failed to produce detectable shifts in fish assemblages within a large number of ALTM lakes. Additional time may simply be needed for biological recovery to progress, or else more proactive efforts may be necessary to restore natural fish assemblages in Adirondack lakes in which water chemistry is steadily recovering from acidification.

New York↗

USGS2006

Interpreting the spatio-temporal patterns of sea turtle strandings: Going with the flow

Knowledge of the spatial and temporal distribution of specific mortality sources is crucial for management of species that are vulnerable to human interactions. Beachcast carcasses represent an unknown fraction of at-sea mortalities. While a variety of physical (e.g., water temperature) and biological (e.g., decomposition) factors as well as the distribution of animals and their mortality sources likely affect the probability of carcass stranding, physical oceanography plays a major role in where and when carcasses strand. Here, we evaluate the influence of nearshore physical oceanographic and wind regimes on sea turtle strandings to decipher seasonal trends and make qualitative predictions about stranding patterns along oceanfront beaches. We use results from oceanic drift-bottle experiments to check our predictions and provide an upper limit on stranding proportions. We compare predicted current regimes from a 3D physical oceanographic model to spatial and temporal locations of both sea turtle carcass strandings and drift bottle landfalls. Drift bottle return rates suggest an upper limit for the proportion of sea turtle carcasses that strand (about 20%). In the South Atlantic Bight, seasonal development of along-shelf flow coincides with increased numbers of strandings of both turtles and drift bottles in late spring and early summer. The model also predicts net offshore flow of surface waters during winter - the season with the fewest relative strandings. The drift bottle data provide a reasonable upper bound on how likely carcasses are to reach land from points offshore and bound the general timeframe for stranding post-mortem (< two weeks). Our findings suggest that marine turtle strandings follow a seasonal regime predictable from physical oceanography and mimicked by drift bottle experiments. Managers can use these findings to reevaluate incidental strandings limits and fishery takes for both nearshore and offshore mortality sources. ?? 2005 Elsevier Ltd. All rights reserved.

Biological Conservation↗

USGS2010

The anatomy of a (potential) disaster: Volcanoes, behavior, and population viability of the short-tailed albatross (Phoebastria albatrus)

Catastrophic events, either from natural (e.g., hurricane) or human-induced (e.g., forest clear-cut) processes, are a well-known threat to wild populations. However, our lack of knowledge about population-level effects of catastrophic events has inhibited the careful examination of how catastrophes affect population growth and persistence. For the critically endangered short-tailed albatross (Phoebastria albatrus), episodic volcanic eruptions are considered a serious catastrophic threat since approximately 80% of the global population of ???2500 birds (in 2006) currently breeds on an active volcano, Torishima Island. We evaluated how short-tailed albatross population persistence is affected by the catastrophic threat of a volcanic eruption relative to chronic threats. We also provide an example for overcoming the seemingly overwhelming problems created by modelling the population dynamics of a species with limited demographic data by incorporating uncertainty in our analysis. As such, we constructed a stochastic age-based matrix model that incorporated both catastrophic mortality due to volcanic eruptions and chronic mortality from several potential sources (e.g., contaminant exposure, fisheries bycatch) to determine the relative effects of these two types of threats on short-tailed albatross population growth and persistence. Modest increases (1%) in chronic (annual) mortality had a 2.5-fold greater effect on predicted short-tailed albatross stochastic population growth rate (lambda) than did the occurrence of periodic volcanic eruptions that follow historic eruption frequencies (annual probability of eruption 2.2%). Our work demonstrates that periodic catastrophic volcanic eruptions, despite their dramatic nature, are less likely to affect the population viability and recovery of short-tailed albatross than low-level chronic mortality. ?? 2009 Elsevier Ltd.

Biological Conservation↗

USGS2018

Identifying cost-effective invasive species control to enhance endangered species populations in the Grand Canyon, USA

Recovering endangered species populations when confronted with the threat of invasive species is an ongoing natural resource management challenge. While eradication of the invasive species is often the optimal economic solution, it may not be a feasible nor desirable management action in other cases. For example, when invasive species are desired in one area, but disperse into areas managed for endangered species, managers may be interested in persistent, but cost-effective means of managing dispersers rather than eradicating the source. In the Colorado River, a nonnative rainbow trout ( Oncorhynchus mykiss ) sport fishery is desired within Glen Canyon National Recreation Area, however, dispersal downriver into the Grand Canyon National Park is not desired as rainbow trout negatively affect endangered humpback chub ( Gila cypha ). Here, we developed a bioeconomic model incorporating population abundance goals and cost-effectiveness analyses to approximate the optimal control strategies for invasive rainbow trout conditional on achieving endangered humpback chub adult population abundance goals. Model results indicated that the most cost-effective approach to achieve target adult humpback chub abundance was a high level of rainbow trout control over moderately high rainbow trout population abundance. Adult humpback chub abundance goals were achieved at relatively low rainbow trout abundance and control measures were not cost-effective at relatively high rainbow trout abundance. Our model considered population level dynamics, species interaction and economic costs in a multi-objective decision framework to provide a preferred solution to long-run management of invasive and native species.

Grand Canyon↗

USGS2019

Explaining harvests of wild-harvested herbaceous plants: American ginseng as a case study

Wild-harvested plants face increasing demand globally. As in many fisheries, monitoring the effect of harvesting on the size and trajectory of resource stocks presents many challenges given often limited data from disparate sources. Here we analyze American ginseng ( Panax quinquefolius L.) harvests from 18 states in the eastern U.S. 1978–2014 to infer temporal patterns and evidence of population declines, and we test the effects of local environmental and socioeconomic factors on ginseng harvesting at the county level 2000–2014. Despite rising prices, annual wild ginseng harvests decreased from a high point in the late 1980s to early 1990s, then, in most, increased after 2005 or 2010 - suggesting range-wide overexploitation notwithstanding federal regulations that, since 1999, restrict minimum harvest age. County-level harvest rates increased with available habitat, road density, poverty and unemployment, but decreased when public land formed a large proportion of county area. Harvests were largest in the Southern Appalachian region. Poverty and accessibility were strongly related to high levels of harvesting. A key implication is that to conserve valuable wild native plant products while also improving local livelihoods, wild cultivation and good stewardship practices must be strongly promoted. Our approach to assessing the condition of wild populations offers a broad template that could be adapted to other wild-harvested plants.

Biological Conservation↗

USGS2021

A global perspective on the influence of the COVID-19 pandemic on freshwater fish biodiversity

The COVID-19 global pandemic and resulting effects on the economy and society (e.g., sheltering-in-place, alterations in transportation, changes in consumer behaviour, loss of employment) have yielded some benefits and risks to biodiversity. Here, we considered the ways the COVID-19 pandemic has influenced (or may influence) freshwater fish biodiversity (e.g., richness, abundance). In many cases, we could only consider potential impacts using documented examples (often from the media) of likely changes, because anecdotal observations are still emerging and data-driven studies are yet to be completed or even undertaken. We evaluated the potential for the pandemic to either mitigate or amplify widely acknowledged, pre-existing threats to freshwater fish biodiversity (i.e., invasive species, pollution, fragmentation, flow alteration, habitat loss and alteration, climate change, exploitation). Indeed, we identified examples spanning the extremes of positive and negative outcomes for almost all known threats. We also considered the pandemic's impact on freshwater fisheries demand, assessment, research, compliance monitoring, and management interventions (e.g., restoration), with disruptions being experienced in all domains. Importantly, we provide a forward-looking synthesis that considers the potential mechanisms and pathways by which the consequences of the pandemic may positively and negatively impact freshwater fishes over the longer term. We conclude with a candid assessment of the current management and policy responses and the extent to which they ensure freshwater fish populations and biodiversity are conserved for human and aquatic ecosystem benefits in perpetuity.

Biological Conservation↗

USGS2026

Fish body midline segmentation using binary search

Body and caudal fin locomotion is ubiquitous in aquatic vertebrates, and kinematic models describing it are used in robotics, biomechanics and fisheries research. This paper presents a new algorithm to translate continuous body midlines of fish into a series of interconnected segments by identifying favorable joint positions along the body. The algorithm employs binary search to generate parsimonious kinematic models, aiming at minimizing the number of segments yet keeping approximation error below a user-defined threshold. To achieve this, the algorithm maximizes the length of each segment by determining the most distal joint position through repetitive shrinking of the search space. Theoretical and empirical analysis using two different datasets show that the binary search algorithm is substantially faster when compared to segment growing algorithm, which employs linear search to generate its models. There is four-fold improvement in computation time when generating models with less than 10 segments, which are typically sufficient to describe fish and fish-inspired robot movements. Furthermore, the multi-segment models generated by the binary search algorithm matched the ground truth models obtained through dynamic programming in over 97% of cases, and on average, contained one fewer segment than those produced by the Ramer–Douglas–Peucker algorithm, which is widely used in curvature simplification tasks. Our findings suggest that the binary search algorithm provides a computationally efficient approach for generating compact kinematic models and may facilitate the analysis of large datasets with high temporal and spatial resolution.

Computers and Electronics in Agriculture↗