Search

Human water use combined with a recent megadrought have reduced river and stream flow through the southwest United States and led to periodic drying of formerly perennial river segments. Reductions in snowmelt runoff and increased extent of drying collectively threaten short‐lived, obligate aquatic species, including the endangered Rio Grande silvery minnow (Hybognathus amarus). This species is subject to boom‐and‐bust population dynamics, under which large fluctuations in abundance are expected to lower estimates of effective population size and erode genetic diversity over time. Rates of diversity loss are also affected by additions of hatchery‐origin fish used to supplement the wild population. We used demographic and genetic data from wild and hatchery individuals to examine the relationship of genetic diversity and effective population size to abundance over the last two decades. Genetic diversity was low during the early 2000s, but diversity and demographic metrics stabilized after the hatchery program was initiated and environmental conditions improved. Yet, from 2017 onward, allelic diversity declined (Cohen's d = 1.34) and remained low despite hatchery stocking and brief wild population recovery. Across the time series, single‐sample estimates of effective population size based on linkage disequilibrium (LD Ne) were positively associated (r = 0.53) with wild abundance and total abundance, but as the proportion of hatchery‐origin spawners increased, LD Ne declined (r = −0.55). Megadrought limited wild spawner abundance and precluded refreshment of hatchery brood stocks with wild fish; hence, we predict a riverine population increasingly dominated by hatchery‐origin individuals and accelerated loss of genetic diversity despite supplementation. We recommend an adaptive and accelerated management plan that integrates river flow management and hatchery operations to slow the pace of genetic diversity loss exacerbated by megadrought. [ABSTRACT FROM AUTHOR]

Warmwater fish habitat in the San Juan River of the southwestern United States has been reduced by over 30% as a result of water depletion, reservoir inundation, and cold‐water dam releases combined with drought‐related changes in hydrology. This reduction and a suite of other factors have contributed to declines in native fish populations including the federally endangered Colorado Pikeminnow (Ptychocheilus lucius) and Razorback Sucker (Xyrauchen texanus). Conservation efforts for these species include determining flow needs; protecting, managing, and augmenting habitats; and stocking hatchery fish. But the young of stocked fish have low survival due largely to a paucity of nursery habitat not being reformed and maintained under current conditions. Flow recommendations for Navajo Dam releases designed to mimic the river's natural hydrograph have not been met due to water shortages, and the desired outcomes of increased channel complexity and enhanced fish habitat have not been observed. Forecasted hydrology that includes ongoing drought shows that achieving the flow targets through further dam reoperations is unlikely. Mechanical construction of early life‐stage habitats is a highly recommended complement to flow management for offsetting the effects of flow reduction and habitat loss. Habitats with features that are effective and resilient under a range of flows are important in counterbalancing the effects of climate change. [ABSTRACT FROM AUTHOR]

We performed experiments in southwestern USA streams to evaluate the efficacy of environmental DNA (eDNA) sampling for two rare small‐bodied minnows: Spikedace Meda fulgida and Loach Minnow Rhinichthys cobitis. We collected eDNA by filtering 5‐L samples and compared detection sensitivity of eDNA assays to traditional sampling methods (electrofishing and seining) by using both techniques at 33 sites in seven streams. We used caged‐fish experiments to estimate eDNA production rates, persistence, and travel distances and to estimate relationships between fish density, biomass, and eDNA quantity. Loach Minnows were detected at 22 sites by both eDNA and traditional sampling, were not detected by either technique at 7 sites, and were detected only by eDNA at 4 sites. Spikedace were detected with both techniques at 15 sites, were not detected by either technique at 8 sites, and were detected only by eDNA at 7 sites. In the Verde River and Wet Beaver Creek, both species' eDNA was detected downstream of caged fish out to our maximum sampling distance of 500 m. Estimated eDNA production rates were greater for Spikedace than for Loach Minnows, although more Spikedace were used. Production rates for both species were greater in the Verde River than in Wet Beaver Creek. Persistence of eDNA did not differ among species but was greater in Wet Beaver Creek than in the Verde River. In density experiments, the amount of Spikedace eDNA was positively related to the density and biomass of caged Spikedace, but the relationship differed between streams. We conclude that eDNA surveys are more sensitive than traditional methods for detecting rare minnows in southwestern streams. With the sensitivity to detect even a single fish in a 100‐m reach, managers will be able to more effectively identify reaches occupied by threatened or endangered fish, even if a population is in decline. [ABSTRACT FROM AUTHOR]

Historical photographs, newspapers, and interviews can provide useful information on the abundance, distribution, and habitat use of rare fish species and can be useful in the development of conservation and management plans for target species. We report on the historical occurrence of Atractosteus spatula (alligator gar) on the Middle Mississippi River (MMR) floodplain near Columbia, Illinois (Monroe County), approximately 280.5 river kilometers above the Ohio River (River Mile 168) during the spring of 1937. Based on measurements taken from a photograph of a captured specimen and Mr. Paul Lopinot's recollection of the specimen's weight, the alligator gar was approximately 2.0 m total length and weighed 60 kg. An additional 25–30 large alligator gar were observed on the floodplain approximately 3.6 km from the river. The loss of seasonally inundated floodplain habitat due to construction of an extensive agricultural levee system on the MMR may be a contributing factor to the decline of the alligator gar in the northern portion of its range. [ABSTRACT FROM AUTHOR]

Rationale: Oxygen isotope ratios (δ18O values) of fish otoliths (ear bones) are valuable geochemical tracers of water conditions and thermal life history. Delta Smelt (Hypomesus transpacificus) are osmerid forage fish endemic to the San Francisco Estuary, California, USA, that are on the verge of extinction. These fish exhibit a complex life history that allows them to survive in a dynamic estuarine environment; however, a rapidly warming climate threatens this thermally sensitive species. Here we quantify the accuracy and precision of using δ18O values in otoliths to reconstruct the thermal life histories of Delta Smelt. Methods: Delta Smelt were reared for 360 days using three different water sources with different ambient δ18Owater values (−8.75‰, −5.28‰, and −4.06‰) and different water temperatures (16.4°C, 16.7°C, 18.7°C, and 20.5°C). Samples were collected after 170 days (n = 28) and 360 days (n = 14) post‐hatch. In situ δ18O values were measured from the core of the otolith to the dorsal edge using secondary ion mass spectrometry (SIMS) to reconstruct temporally resolved thermal life histories. Results: The δ18Ootolith values for Delta Smelt varied as a linear inverse function of water temperature: 1000 ln α = 18.39 (±0.43, 1SE)(103TK−1) − 34.56 (±1.49, 1SE) and δ18Ootolith(VPDB) − δ18Owater (VPDB) = 31.34(±0.09, 1SE) − 0.19(±0.01, 1SE) × T ° C. When the ambient δ18Owater value is known, this species‐specific temperature‐dependent oxygen isotope fractionation model facilitated the accurate (0.25°C) and precise (±0.37°C, 2σ) reconstruction of the water temperature experienced by the fish. In contrast, the use of existing general fractionation equations resulted in inaccurate temperature reconstructions. Conclusions: The species‐specific δ18Ootolith fractionation equation allowed for accurate and precise reconstructions of water temperatures experienced by Delta Smelt. Characterization of ambient δ18Owater values remains a critical next step for reconstructing thermal life histories of wild Delta Smelt. This tool will provide new insights into habitat utilization, potential thermal refugia, and resilience to future warming for this critically endangered fish. [ABSTRACT FROM AUTHOR]

Sturgeons are the most vulnerable vertebrate group in the world, yet little is known about their biology and ecology. A ban of most of their wild harvest has generated a dramatic increase of interest in production of sturgeon from aquaculture. Shortnose sturgeon, Acipenser brevirostrum , are listed as a species of special concern in Canada, listed as endangered in the US, and has been under aquaculture development in Canada for > 15 years. It is important to be able to delineate sex for both aquaculture production and determination of sex ratios in the wild. Sturgeons are thought to be sexually monomorphic. Currently, sturgeons are sexed using surgically invasive methods and/or expensive ultrasonography. We used geometric morphometrics (a combination of Procrustes superimposition, canonical variate analysis and MANOVA) on cephalic homologous landmarks to test if shortnose sturgeon were sexually dimorphic. A total of 110 shortnose sturgeon (ranging in size from 3–6 kg and 6–8 years of age) provided by Breviro Caviar, New Brunswick, Canada, were imaged and then sexed using a combination of ultrasound, terminal sampling and visual examination of gonads to create a working set of fish of known sex. Each fish was imaged dorsally, laterally and ventrally. We found that shortnose sturgeon are sexually dimorphic and not monomorphic. The sorting accuracy of the algorithm was tested using a jackknife test and was found to be 99% accurate when three views were in agreement. Using the landmarks from geometric morphometrics we developed an equation using discriminant function analysis to sort sex based on angular relationships (accuracy of 83%). Geometric morphometrics is a method that is accessible to any user and can provide useful metrics regarding sex identification for aquaculture production. [ABSTRACT FROM AUTHOR]

High levels of total suspended sediment (TSS) can have negative consequences on fishes, such as altering food supply, lowering food acquisition, clogging gills, and disrupting reproduction. While effects of TSS on salmonids and estuarine fish are well studied, less is known about possible negative impacts of suspended sediment on desert fishes. Several imperiled desert fishes inhabit streams and springs near the U.S.–Mexico border and are potentially threatened by increased sediment loads from borderlands activity such as livestock grazing, road building, illegal traffic, and law enforcement patrols. One such species is the Yaqui ChubGila purpurea,a federally listed endangered cyprinid. We exposed Yaqui Chub embryos and fry (mean TL = 12.6 mm; SE = 0.42) to a range of TSS levels commonly found in one of the only streams they inhabit, Black Draw, which crosses the Arizona–Mexico border. We tested effects of 0; 300; 500; 1,000; 5,000; and 10,000 mg/L TSS loads on fry and embryos over a 5-d period in three replicate containers for each treatment. Fifty percent hatch rate (i.e., median lethal concentration, LC50) was 3,977 mg/L for embryos. The LC50 for fry (concentration at which half died) was 8,372 mg/L after 12 h of exposure; however, after 5-d exposure, LC50 leveled at 1,197 mg/L. The TL of fry did not change significantly in any treatment over the 5-d period. Suspended sediment in Black Draw reached concentrations lethal to Yaqui Chub embryo and fry during four floods in 2012. Although some desert fishes have evolved in rivers and streams subject to elevated TSS and are tolerant to high TSS concentrations, other fish species are less tolerant and may be impacted by land practices which increase erosion into stream systems. Management of critically endangered desert fishes should include considerations of the effects of increased suspended sediment. Received September 5, 2014; accepted November 10, 2014 [ABSTRACT FROM AUTHOR]

Given the general pattern of invasions with severe ecological consequences commonly resulting from multiple introductions of large numbers of individuals on the intercontinental scale, we explored an example of a highly successful, ecologically significant invader introduced over a short distance, possibly via minimal propagule pressure. The Sacramento pikeminnow ( Ptychocheilus grandis) has been introduced to two coastal rivers in northern California where it poses a risk to threatened and endangered fishes. We assayed variation in seven microsatellite loci and one mitochondrial DNA gene to identify the source populations and estimate founder numbers for these introductions. Our analysis suggests that successful invasion of the Eel River was likely the result of a single transfer of 3-4 effective founders from nearby within the species' native range: Clear Lake or its outflow Cache Creek. The other introduced population (Elk River), known from only seven individuals, likely represents secondary expansion from the introduced Eel River population. Our findings highlight the threat posed by close-range invaders and the ability of some fishes to rapidly invade ecologically suitable areas despite small effective founding numbers. [ABSTRACT FROM AUTHOR]

Identification of critical habitat is a key step in conservation and recovery of endangered and threatened freshwater fish. Critical habitat under Canadian and US legislation may include habitat that is not directly used by listed fish, provided it is necessary for species conservation or recovery. Riparian habitat meets biological criteria for critical habitat because riparian zones are integral to aquatic ecosystem functions of importance to many fish species and other organisms. These functions include provision of shade for temperature-sensitive species, control of channel complexity and sediment inputs through bank stabilization, input of large wood and allochthonous energy sources, and filtering of nutrients and toxins from adjacent land. In response to decades of stream-riparian research, widespread implementation of regulations to protect riparian zones in most developed countries represent a de facto consensus that riparian buffers are essential for aquatic ecosystem health and the maintenance of populations of fish and other species. Consistent with widespread riparian regulations deemed necessary to protect not-at-risk species, riparian habitat adjacent to a body of water containing a listed freshwater species should be considered biologically critical unless the habitat requirements of individual taxa are demonstrated to be insensitive to the ecological functions associated with riparian habitat. L’identification de l’habitat critique est une étape essentielle dans la conservation et la récupération des poissons d’eau douce menacés et en voie de disparation. Dans les législations canadienne et américaine, l’habitat critique peut inclure des milieux qui ne sont pas directement utilisés par les poissons concernés, à la condition qu’ils soient nécessaires pour la conservation ou la récupération de ces espèces. Les habitats riverains possèdent les critères biologiques d’habitats critiques parce que les zones riveraines sont nécessaires pour assurer des fonctions de l’écosystème aquatique d’importance pour plusieurs espèces de poissons et pour d’autres organismes. Ces fonctions incluent la production d’ombre pour les espèces sensibles à la température, le contrôle de la complexité du chenal et des apports de sédiments par la stabilisation des rives, l’apport de sources d’énergie allochtones et de débris ligneux de grande taille et la filtration des nutriments et des toxines provenant des terres adjacentes. À la suite de décennies de recherche sur la relation entre les cours d’eau et la zone riveraine, la mise en application très commune dans la plupart des pays développés de règlements pour protéger les zones riveraines représente un consensus de facto reconnaissant que les zones tampons riveraines sont essentielles à la santé des écosystèmes aquatiques et le maintien des populations de poissons et d’autres espèces. En accord avec les règlements largement répandus sur les zones riveraines jugées nécessaires pour la protection des espèces non vulnérables, tout habitat riverain adjacent à un milieu aquatique contenant une espèce d’eau douce figurant sur la liste des espèces en péril devrait être considéré comme biologiquement critique, à moins qu’on démontre que les besoins d’habitat de ce taxon particulier sont insensibles aux fonctions écologiques associées à l’habitat riverain. [ABSTRACT FROM AUTHOR]

In response to a petition to list Great Basin redband trout (subspecies of rainbow trout Oncorhynchus mykiss) as threatened or endangered, the U.S. Fish and Wildlife Service conducted a status review in 1998. To support that review, we conducted a survey of the abundances of redband trout in each of six subbasins of the Great Basin that included the states of Oregon, California, and Nevada. We used a generalized random-tessellation stratified algorithm to select a target sample size of 35 sites/subbasin. Out of a target number of 210 sites, 185 were visited by three-person crews that surveyed stream habitat and estimated the abundance of fish populations in sample reaches with lengths that were nearly 20 times the respective channel widths. A minimal sampling intensity was based on previously encountered levels of between-site variance in estimates of redband trout abundance. The total population estimate of age-1 and older (age-1+) redband trout in the Great Basin was 971,313 fish, with a 95% confidence interval equaling ± 15% of the mean estimate; 95% confidence limits ranged from 15% to 31% for population estimates in individual subbasins. Age-l+ fish abundance in terms of numerical density showed no significant differences between any subbasins. However, there were significant differences in terms of biomass: Catlow Valley subbasin biomass was significantly higher than the Great Basin mean, whereas Goose Lake subbasin biomass was significantly lower than the basinwide mean. These comparisons were supported by like differences in average weight. Analysis of stream habitat characteristics and fish abundance revealed no relationships that were generally consistent throughout the Great Basin, although spatial patterns were evident within some stream systems where sampling intensity was sufficiently high. [ABSTRACT FROM AUTHOR]

BACKGROUND: Mixtures of organophosphate and carbamate pesticides are commonly detected in freshwater habitats that support threatened and endangered species of Pacific salmon (Oncorhynchus sp.). These pesticides inhibit the activity of acetylcholinesterase (AChE) and thus have potential to interfere with behaviors that may be essential for salmon survival. Although the effects of individual anticholinesterase insecticides on aquatic species have been studied for decades, the neurotoxicity of mixtures is still poorly understood. OBJECTIVES: We assessed whether chemicals in a mixture act in isolation (resulting in additive AChE inhibition) or whether components interact to produce either antagonistic or synergistic toxicity. METHODS: We measured brain AChE inhibition in juvenile coho salmon (Oncorhynchus kisutch) exposed to sublethal concentrations of the organophosphates diazinon, malathion, and chlorpyrifos, as well as the carbamates carbaryl and carbofuran. Concentrations of individual chemicals were normalized to their respective median effective concentrations (EC50) and collectively fit to a nonlinear regression. We used this curve to determine whether toxicologic responses to binary mixtures were additive, antagonistic, or synergistic. RESULTS: We observed addition and synergism, with a greater degree of synergism at higher exposure concentrations. Several combinations of organophosphates were lethal at concentrations that were sublethal in single-chemical trials. CONCLUSION: Single-chemical risk assessments are likely to underestimate the impacts of these insecticides on salmon in river systems where mixtures occur. Moreover, mixtures of pesticides that have been commonly reported in salmon habitats may pose a more important challenge for species recovery than previously anticipated. [ABSTRACT FROM AUTHOR]

Endangered and threatened populations of Pacific salmon (Oncorhynchus spp.) in the United States span major freshwater and marine ecosystems from southern California to northern Washington. Their wide-ranging habits and anadromous life history exposes them to a variety of risk factors and influences, including hydropower operations, ocean and freshwater harvest, habitat degradation, releases of hatchery-reared salmon, variable ocean productivity, toxic contaminants, density-dependent effects, and a suite of native and non-native predators and competitors. We review the range of analyses that form the scientific backbone of recovery plans being developed for Pacific salmon listed under the U.S. Endangered Species Act. This process involves: identifying the appropriate conservation units (demographically independent Evolutionarily Significant Units [ESUs] and their populations), developing viability criteria for Pacific salmon populations and overall ESUs, and using coarse-resolution habitat analyses and life-cycle modeling to identify likely consequences of alternative actions proposed to achieve recovery. Adopting this wide breadth of analyses represents a necessary strategy for recovering Pacific salmon and a model for conservation planning for other wide-ranging species. [ABSTRACT FROM AUTHOR]

Abstract: The razorback sucker (Xyrauchen texanus) is listed as federally endangered throughout its range. A massive recovery effort by the Recovery Implementation Program for Endangered Fish Species in the Upper Colorado River Basin has focused its efforts in the upper Colorado River. The upper Colorado River basin also has two locations that have been identified by the National Irrigation Water Quality Program as having substantial selenium contamination. Selenium is toxic to fishes, affecting reproductive success. Thus, there is concern about potential effects of selenium on the endangered razorback sucker. Two sets of studies have investigated the effects of selenium on razorback suckers, but study results are conflicting. This commentary evaluates studies that claim selenium is not a problem for razorback sucker. We find that study bias was so pervasive that purported conclusions were unwarranted. Contaminated control water, older life stages of fish tested, lack of methodology for analysis of selenium in water, diet, or fish, use of rotifer food, low feeding rates, low growth rates of fish, and improper storage of site waters resulted in an apparent erroneous linkage of high selenium in whole-body residues with no adverse effects. [Copyright &y& Elsevier]

Summary 1. Conservation of the federally endangered Roanoke logperch (Percina rex , Jordan and Evermann) necessitates protection of habitat that is critical for all age classes. We examined habitat use patterns of individual logperch to determine: (1) if age classes of logperch in the Nottoway and Roanoke Rivers exhibit habitat selectivity, (2) if age classes differ in habitat use, and (3) if ontogenetic patterns of habitat use differ between the Roanoke and Nottoway river populations. 2. In the summers of 2000 and 2001, we observed 17 young-of-year (YOY) logperch [<4 cm total length (TL)], 13 subadult logperch (4–8 cm TL), and 49 adult logperch (>8 cm TL) in the upper Roanoke River, and 40 subadult and 39 adult logperch in the Nottoway River, Virginia. 3. All size classes of Roanoke logperch demonstrated habitat selectivity and logperch used a wide range of habitats in the Roanoke and Nottoway rivers during ontogeny. Habitat use by logperch varied among age classes and between rivers. 4. In the Roanoke River, adult and subadult logperch primarily preferred run and riffle habitat, often over gravel substrate. Subadults were found in lower water velocities and slightly more embedded microhabitats than adults. YOY logperch were found in shallow, stagnant backwaters and secondary channels. In the Nottoway River, both adult and subadult logperch were found over sand and gravel in deep, low-velocity pools and runs. Subadults were observed in slightly more silted, lower velocity habitat than adults. Shifts in habitat use were more distinct between age classes in the Roanoke River than the Nottoway River. 5. Successful conservation of this species will involve sound understanding of spatial variation in habitat use over logperch life history and preservation of the ecological processes that preserve required habitat mosaics. [ABSTRACT FROM AUTHOR]

Discusses the possible listing of the steelhead trout on the US Endangered Species List as of July 1997. The dwindling fish populations on the west coast of the United States; Other fish that have been put on the list; The history of steelhead trout fishing; The social, political, and economic consequences of the trout being put on the list; Causes for the decline of the trout.

• Range size estimates are highly correlated across data types and approaches. • Taxonomy does not bias range size estimates. • Ranked range sizes varied most for species with intermediate range sizes. • The rarest fishes are consistently identified across data types and approaches. • Open access biodiversity data is valuable in assessments of geographic rarity. Geographic rarity is a driver of a species' intrinsic risk of extinction. It encompasses multiple key components including range size, which is one of the most commonly measured estimates of geographic rarity. Range size estimates are often used to prioritize conservation efforts when there are multiple candidate species, because data for other components of rarity such as population size are sparse, or do not exist for species of interest. Range size estimates can provide rankings of species vulnerability to changing environments or threats, identifying rare species for future study or conservation initiatives. However, range sizes can be estimated by several different metrics, and the degree of overlap in the identification of the rarest or most common species across methodologies is not well understood. This knowledge gap compromises our ability to prioritize correctly rare species, and presents a particularly difficult challenge for stream-dwelling organisms with distributions constrained to river networks. We evaluated the relationship of multiple range size estimates of a subset of freshwater fishes native to the United States to determine the degree of overlap in rarity rankings using different data sources and grain sizes. We used publicly available, open access data from the Global Biodiversity Information Facility (GBIF) to calculate extent of occurrence (minimum convex polygons) and area of occupancy (total area occupied, measured across various grain sizes). We compared range sizes estimated using GBIF data with the best available estimates of current distributions described by publicly available digital maps (NatureServe) to evaluate the efficacy of GBIF data in assessments of range size. We found strong correlations between range size estimates across analytical approaches and data sources with no detectable bias of taxonomy. We found that variation among rarity rankings was highest for species with intermediate range sizes indicating that the approaches considered here generally converge when used to identify the rarest or the most common species. Importantly, our results show that the rarest, and perhaps the most vulnerable, species are consistently identified across common methodological approaches. More broadly, our results support the use of open access biodiversity data that include opportunistically collated and collected point occurrence records as a complement to coarse-grain (e.g., whole range map) approaches, as we observed no systematic bias or deviation across data sources in our analyses. This indicates databases such as the GBIF may help fill important fundamental and applied knowledge gaps for many poorly understood species, particularly in a broad-scale, multispecies framework. [ABSTRACT FROM AUTHOR]

Climate change is expected to increase weather extremes and variability, including more frequent weather whiplashes or extreme swings between severe drought and extraordinarily wet years. Shifts in precipitation patterns will alter stream flow regimes, affecting critical life history stages of sensitive aquatic organisms. Understanding how threatened fish species, such as steelhead/rainbow trout (Oncorhynchus mykiss), are affected by stream flows in years with contrasting environmental conditions is important for their conservation. Here, we report how extreme wet and dry years, from 2015 to 2018, affected stream flow patterns in two tributaries to the South Fork Eel River, California, USA, and aspects of O. mykiss ecology, including over‐summer fish growth and body condition as well as spring out‐migration timing. We found that stream flow patterns differed across years in the timing and magnitude of large winter–spring flow events and in summer low‐flow levels. We were surprised to find that differences in stream flows did not impact growth, body condition, or timing of out‐migration of O. mykiss. Fish growth was limited in the late summer in these streams (average of 0.02 ± 0.05 mm/d), but was similar across dry and wet years, and so was end‐of‐summer body condition and pool‐specific biomass loss from the beginning to the end of the summer. Similarly, O. mykiss migrated out of tributaries during the last week of March/first week of April regardless of the timing of spring flow events. We suggest that the muted response to inter‐annual hydrologic variability is due to the high quality of habitat provided by these unimpaired, groundwater‐fed tributaries. Similar streams that are likely to maintain cool temperatures and sufficient base flows, even in the driest years, should be a high priority for conservation and restoration efforts. [ABSTRACT FROM AUTHOR]

This section offers news briefs on fisheries as of October 2009. About 50% of the fish and shellfish consumed worldwide are produced through aquaculture. The Federal Court of Canada issued a decision which holds that the Minister of Fisheries and Oceans violated the Species At Risk Act (SARA) by allowing an endangered species recovery plan for the Nooksack dace. The U.S. Environmental Protection Agency (EPA) imposed restrictions on three pesticides aimed at protecting endangered Pacific salmon.

The article focuses on Moapa coriacea which is commonly known as Moapa dace and is considered as endangered species by the International Union for Conservation of Nature and Natural Resources (IUCN). The U.S. Department of the Interior (DIO) has supported the IUCN in preserving and protecting the species from their habitat. In addition, the species has been threatened by nonnative species, ground-water pumping and excessive water withdrawal.

The article presents a description of the endangered fish, Batrochoglanis mathisoni. Belonging to the family Pseudopimelodidae, the fish is commonly called Bagre manchado and sapo in Venezuela and giant bumblebee catfish in the U.S. Its features include wide, large and depressed head, wide mouth, small eyes with a short and robust body and compressed caudal peduncle. The body is black or dark brown in color with light band from dorsal fin onto perctoral fins and scattered irregular black spots. The fish's preferred habitats are clearwater piedmont and lowland streams of moderate flow over rocks.

This article describes the Oregon Chub fish (Oregonichthys crameri) (Snyder, 1908) (Cyprinidae) one of the threatened fishes of the world. This fish is protected by state law in Oregon. It is listed as a species of concern under the U.S. Endangered Species Act. Its features are described in detail and it is compared with other species with which it is associated. The author discusses the species' entire range and population distributions. He also describes how the fish utilizes various habitats during different seasons. The fish's diet is described as are the environmental conditions it prefers or tolerates. Interspecies competition is discussed along with preferred substrates. The fish's life-cycle is described and threats are listed together with conservation actions and recommendations.

This article describes the Carolina pygmy fish (Elassoma boehlkei) one of the threatened fishes of the world. This fish is protected by state law in North Carolina. It is listed as a species of concern under the U.S. Endangered Species Act. Its features are described in detail and it is compared with other similar species. The authors discuss the species' entire range and population distributions. They also describe how the fish utilizes various habitats during different seasons. The fishes’ diet is described as is the environment conditions it prefers or tolerates. Interspecies competition is discussed along with preferred substrates. The fishes’ life-cycle is described and threats are listed together with conservation actions and recommendations.

This article discusses research showing that sport-fishing accounts for nearly one-quarter of the total take of several dozen overfished populations. Anyone who has read Ernest Hemingway's depiction of the exhausting, epic struggle between a fisherman and his big fish quarry in "The Old Man and the Sea" might be hard pressed to imagine how recreational saltwater fishers could possibly overfish the oceans. And although times have certainly changed in sport-fishing since the book was written in 1952--more than 10 million recreational fishers ply U.S. coastal waters today--many fishers remain skeptical that their relatively low-tech rods and reels could have much of an impact. However, Florida State University marine ecologist Felicia Coleman and her team report that sport-fishing accounts for nearly one-quarter of the total take of several dozen overfished populations. For some depleted species--particularly the popular large fishes--the study found that recreational landings outstrip commercial landings. Sport-fishing advocates are concerned about conclusions marine conservationists have drawn from Coleman's work--that marine protected reserves should be implemented, banning commercial as well as recreational fishing in certain areas to help overfished species recover. Such "no-take" zones, say many recreational fishers, should be created only after all other measures have been exhausted. "We have a good track record of conservation," says Michael Nussman, president of the American Sport-fishing Association in Alexandria, Virginia. As an example, he points to the success of catch limits and seasonal closings in restoring striped bass populations off the Atlantic coast. Coleman and other researchers disagree, however. Catch limits restrict the amount of fish caught by individual fishers, not the total amount caught by all sport-fishers, Coleman says.

Reports on regulatory developments related to science in the United States, as of April 27, 2001. United States National Marine Fisheries Service's addition of the smalltooth sawfish to its list of endangered species; Panel formed to review the control of astronomy research; U.S. Environmental Protection Agency's request to the National Academy of Sciences to study the health impacts of arsenic in drinking water.

Examines the U.S. Supreme Court decision which upheld a lower court order forbidding the operation of the Tellico Dam in Tennessee due to its impact on the endangered snail darter. Details of the case; Arguments by supporters and opponents of the dam project; Justification of the court decision.

The article reports on the findings of the research conducted by the Cornell University in Ithaca, New York regarding the recovery of a threatened fish species known as the sturgeon. The researchers have provided evidence of the recovery of the shortnose sturgeon in the Hudson River, which flows through New York City. It was found that the sturgeon population rose by more than 400% since 1970, although it is considered endangered in other rivers in North America. According to the article, this result is a boost for the beleaguered Endangered Species Act, which has only been able to claim a population recovery since its inception in 1966.

The article reports on the warnings issues by the U.S. Environmental Protection Agency to thousand of stores in hundreds of west coast communities about hazards of common household pesticides to salmon. Stores located near streams used by threatened salmon are required to show the warning signs if they are selling products containing any of seven pesticides. The purpose of the signs is to encourage people to find pesticide-free ways to take care of their lawns, yards and gardens.