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Objective: We used passive acoustic monitoring (PAM) and automatic detection of spawning splashes to examine the timing and environmental drivers of spawning in river herring (Alewife Alosa pseudoharengus and Blueback Herring A. aestivalis). Methods: Acoustic recordings of spawning splashes were collected from March to May 2021 in the Choptank River, Maryland, using an AudioMoth recorder. Recordings were analyzed using a random forest model on the Rainforest Connection ARBIMON platform to determine hourly presence–absence of splashes. Result: At a seasonal scale, our results suggested two peaks in spawning activity: early March and mid‐April, corresponding with the known phenologies of Alewife and Blueback Herring. Hourly patterns in spawning activity suggested distinct diel cycles, with spawning most concentrated at dawn. In contrast, sonar fish counts collected for 1 week during the season indicated that migration occurred throughout daylight hours. We also found a potential relationship between spawning activity and the presence of great blue herons Ardea herodias. Conclusion: Overall, our results demonstrate that PAM can be an efficient and affordable method for studying the spawning ecology of anadromous fish. Impact statementMonitoring fish migrations in rivers can be costly and time consuming. We present a method that automatically detects the splashing sounds some fish make when they spawn. Using this efficient method, we examine the timing and environmental drivers (e.g., temperature, tides, predators) of spawning in river herring. [ABSTRACT FROM AUTHOR]

Grove L, Stell EG, Grove LJW, Wright RA, DeVries DR. 2022. Influence of blueback herring, Alosa aestivalis, on zooplankton in a southeastern US reservoir. Lake Reserv Manage. 38:256–267. Forage fishes like blueback herring (Alosa aestivalis) have been widely introduced, sometimes without careful consideration of potential ecological consequences. We compared biotic and abiotic factors before and after blueback herring introduction into Lewis Smith Lake, Alabama (United States), and tested for diet overlap among planktivorous species to quantify their potential ecological influences. Abiotic and biotic factors varied among regions of the lake, consistent with differences in agricultural practices and nutrient input within each region. Secchi depth increased and zooplankton density decreased, while chlorophyll a remained unchanged relative to before blueback herring introduction. Juvenile and adult blueback herring and threadfin shad (Dorosoma petenense) consumed the same zooplankton taxa; however, blueback herring consumed significantly larger individuals and significantly greater numbers of zooplankton than threadfin shad. Blueback herring also selectively consumed larger zooplankton than the average size in the reservoir population, while threadfin shad did not. Threadfin shad and blueback herring positively selected Bosmina and cyclopoid copepods. The taxonomic overlap and size selectivity in prey choice suggest that if blueback herring reduce larger zooplankton, threadfin shad and blueback herring diets are likely to increasingly overlap. Because of their differences in feeding strategies (i.e., related to zooplankton size differences) and habitat preferences, current evidence for potential competitive interactions between these planktivores appears limited; however, longer term concerns are that blueback herring could eventually reduce larger zooplankton to the extent where they would increasingly compete with threadfin shad as the most abundant forage fish in Lewis Smith Lake. [ABSTRACT FROM AUTHOR]

Anadromous alosines are widespread throughout the Northern Hemisphere. Juveniles of this clade are notoriously fragile animals that are at high risk of injury and death associated with passage at hydroelectric facilities. Although turbine mortality is a common concern, conditions encountered when bypassed around these routes may also be hazardous. Downstream bypass structures typically discharge into plunge pools, which are highly turbulent and may cause mechanical injury. We subjected live, actively migrating juvenile blueback herring to a suite of realistic plunge pool conditions (3 m drop, pool depth of 60–180 cm, and discharge of 0.28–1.70 m3/s) and monitored them for ≥ 96 h. Survival was generally higher than expected (>80% in all cases). However, both plunge pool volume and total discharge affected survival with elevated discharge and shallow conditions associated with increased mortality. Mortality was often delayed: rates remained elevated throughout the monitoring period, indicating that survival studies based on shorter periods underestimate total mortality.

Anadromous river herring have declined in many parts of their range, leading to fisheries management efforts to help repopulate this species by improving connectivity of rivers and restoring populations by fish transfers. With data lacking on parasites in these species, this study sought to better understand myxozoans across various life stages and habitats in river herring populations in New Jersey, USA. We compared fish from riverine habitats during early-life growth and adults returning to spawn, marine-phase fish, and landlocked Alewife populations. Three myxozoan species were identified in young-of-the-year (YOY) anadromous river herring, including Kudoa clupeidae in the skeletal musculature, Myxobolus mauriensis in the rib cartilage, and an uncharacterized coelozoic myxozoan within the lumen of mesonephric tubules. In YOY river herring, Blueback Herring were 2 times more likely to be infected by K. clupeidae than Alewife (p = 0.019) and in the Maurice River, fish were 4 times more likely to be infected with M. mauriensis than fish from Great Egg Harbor River (p = 0.000) and 11 times more likely than the Delaware River (p = 0.001). Spawning adult river herring were infected with a previously undescribed myxozoan parasite infecting the kidney. Sequencing the 18S rDNA indicated this species is closely related to Ortholinea species. Myxobolus mauriensis and the Ortholinea-like species were absent from marine-phase river herring indicating that infections were linked to river environments occurring during early-life growth and spawning, respectively. No myxozoans were present in landlocked Alewife, showing that similar infections occurring in rivers were absent in lake environments in the region. [ABSTRACT FROM AUTHOR]

Microplastics in aquatic environments, and specifically their effects on the health of organisms, are of growing concern worldwide. Of particular concern are microplastics in a similar size range to zooplankton, as they have been found in the digestive tracks of organisms, such as fish, who typically seek zooplankton as a food source. It is unclear, however, to what degree, if any, fish select for or against microplastic particles when feeding. It is also unclear whether ingestion of microplastics affects fish condition. To answer these questions, the estimated physical condition and degree of selective feeding on microplastics were determined for juvenile fish collected from the Hudson River. Considering only particles 0.335–5.0 mm, microplastics made up 12% of fish diets but 21% of particles found in the surrounding water column. Relying on Jacob's Modified Electivity (JME) to quantify selectivity in feeding, our results reveal selective feeding on zooplankton and avoidance of microplastics. There was no correlation between condition and degree of selectivity toward any particular food types, including microplastics. Future work needs to consider fish with different feeding strategies and potential bioaccumulation of microplastics in the food web. Fish selectivity of ingestion in regards to microplastics should additionally be tested on wider spatial and temporal scales. • Blueback herring in the Hudson River preferentially avoid consuming microplastics. • Microplastics of all types and colors (tan excepted) are avoided. • Diet selectivity regarding microplastics does not affect coefficient of condition. [ABSTRACT FROM AUTHOR]

Anthropogenic activities are placing increasing pressure on many species, particularly those that rely on more than one ecosystem. River herring (alewife, Alosa pseudoharengus and blueback herring, A. aestivalis collectively) are anadromous fishes that reproduce in rivers and streams of eastern North America and migrate to the western Atlantic Ocean. Here, we use data from single nucleotide polymorphisms (SNPs) to provide a comprehensive analysis of population structure for both species of river herring throughout their native ranges. We sampled river herring spawning runs in rivers from Newfoundland to Florida, examining a total of 108 locations, and genotyping over 8000 fish. We identified geographic population groupings (regional genetic groups) in each species, as well as significant genetic differentiation between most populations and rivers. Strong correlations between geographic and genetic distances (i.e., isolation by distance) were found range-wide for both species, although the patterns were less consistent at smaller spatial scales. River herring are caught as bycatch in fisheries and estimating stock proportions in mixed fishery samples is important for management. We assessed the utility of the SNP datasets as reference baselines for genetic stock identification. Results indicated high accuracy of individual assignment (76–95%) to designated regional genetic groups, and some individual populations, as well as highly accurate estimates of mixing proportions for both species. This study is the first to evaluate genetic structure across the entire geographic range of these species and provides an important foundation for conservation and management planning. The SNP reference datasets will facilitate continued multi-lateral monitoring of bycatch, as well as ecological investigation to provide information about ocean dispersal patterns of these species. [ABSTRACT FROM AUTHOR]

Blueback Herring Alosa aestivalis populations throughout the East Coast have declined precipitously since the late 1980s and were listed as a Species of Concern in 2006 by the National Oceanic and Atmospheric Administration. Natural resource agencies are attempting to restore this species to viable and sustainable levels with fry stockings cultured in hatcheries. To evaluate the long-term contribution of stockings to populations, agencies need an accurate method to track these stocking efforts. Genetic parentage-based tagging is recognized as a feasible means of assessing hatchery contribution of stocked fish to rivers of interest. However, Blueback Herring lack a reliable set of genetic markers to conduct parentage-based tagging. To this end, we analyzed previously described microsatellites as well as new microsatellite markers identified through NextGeneration sequencing to create a suite of 14 Blueback Herring markers useful for parentage-based tagging. The markers were successful in parentage analysis for Blueback Herring collected from the Chowan River, North Carolina. An additional challenge in the management of Blueback Herring is the ability to phenotypically distinguish Blueback Herring from the closely related Alewife Alosa pseudoharengus. Furthermore, recent studies provide evidence that these two species, collectively referred to as river herring, may be hybridizing with one another in some systems. Microsatellite marker AsaC334 can be utilized to discriminate between the two species, as well as to identify their F1 hybrids, thereby providing another genetic tool for hatchery management. [ABSTRACT FROM AUTHOR]

River herring (AlewifeAlosa pseudoharengusand Blueback HerringA. aestivalis) populations have declined dramatically along the U.S. Atlantic coast. Conservation efforts are currently inhibited by an incomplete understanding of stock structure for the upper Chesapeake Bay, which once supported some of the largest spawning runs across the species’ ranges. We collected genetic samples from 512 adult river herring from five rivers and used microsatellites to explore genetic differentiation and population structure. Juvenile abundance indices were also evaluated for spatiotemporal patterns using time series analyses. Statistically significant allelic heterogeneity was observed among most collections, and we identified genetically distinguishable groups for each species. Regression analysis indicated stable or declining juvenile abundance, and empirical orthogonal function analysis supported groupings of tributaries based on temporal patterns in abundance. Results suggest a divide between eastern shore and western shore tributaries, with the Susquehanna River and the head of the bay showing similarities to both groups and possible temporal shifts in genetic structure due to straying. The Patuxent River likely represents a third genetic group for Blueback Herring. Cumulatively, our results suggest at least two genetically distinguishable groups of spawning populations for Alewives and at least three for Blueback Herring; these groups should be considered separately for conservation and management. Received December 22, 2016; accepted June 3, 2017 Published online August 31, 2017 [ABSTRACT FROM AUTHOR]

Freshwater habitat alteration and marine fisheries can affect anadromous fish species, and populations fluctuating in size elicit conservation concern and coordinated management. We describe the development and characterization of two sets of 96 single nucleotide polymorphism ( SNP) assays for two species of anadromous alosine fishes, alewife and blueback herring (collectively known as river herring), that are native to the Atlantic coast of North America. We used data from high-throughput DNA sequencing to discover SNPs and then developed molecular genetic assays for genotyping sets of 96 individual loci in each species. The two sets of assays were validated with multiple populations that encompass both the geographic range and the known regional genetic stocks of both species. The SNP panels developed herein accurately resolved the genetic stock structure for alewife and blueback herring that was previously identified using microsatellites and assigned individuals to regional stock of origin with high accuracy. These genetic markers, which generate data that are easily shared and combined, will greatly facilitate ongoing conservation and management of river herring including genetic assignment of marine caught individuals to stock of origin. [ABSTRACT FROM AUTHOR]

River herring populations, including Alosa pseudoharengus and Alosa aestivalis, have significantly declined as a result of anthropogenic factors throughout their range in eastern North America. To better understand the health of the species, parasite surveys were conducted in several New Jersey rivers. A novel myxozoan parasite, Myxobolus mauriensis n. sp., is described infecting the cartilage of pleural ribs in young-of-the-year fish. The parasite forms large polysporic plasmodia forming pseudocysts within the ribs, which extend into the musculature. Pathology associated with infection includes costochondritis, breaks in the rib bones, and deformed bone growth. Rupture of large pseudocysts and release of mature spores are associated with myositis, dermatitis, and peritonitis. Phylogenetic analysis reveals that M. mauriensis n. sp. occurs in a long-branching clade basal to other myxobolids, grouping with several Myxobolus species from marine fish ( Myxobolus groenlandicus, Myxobolus aeglefini, and Myxobolus albi). The closest identity is to M. groenlandicus, with 83% identity based on a 1,762-bp sequence of the SSU 18S rDNA. Similarly, spore morphology, tropism for cartilage, and association with marine/brackish environments are shared in these 4 species. Mature spores of M. mauriensis n. sp. are similar to other reported myxobolids, though spores are slightly wider (12.1 ± 0.44 μm) than long (11.4 ± 0.44 μm), with a length:width relationship of 0.94 (±0.04), a feature not commonly described for other species of Myxobolus. Prevalence was studied by histology and fresh observation. In both Blueback Herring and Alewife, the highest infection prevalence occurred in the Maurice River at around 20%, and lower prevalence was found in the Great Egg Harbor River at around 5%. In the Delaware River, prevalence was about 2% in Blueback Herring, while the parasite was not detected in Alewife samples. [ABSTRACT FROM AUTHOR]

Concern over the impacts of incidental catches of Alewife, Alosa pseudoharengus and Blueback Herring, A. aestivalis (collectively managed as 'river herring') in the commercial Atlantic Herring (Clupea harengus) and Atlantic Mackerel (Scomber scombrus) fisheries has resulted in the recent implementation of river herring incidental catch limits. These incidental catches are highly variable in frequency and magnitude, and the environmental conditions associated with these catches are poorly understood. We used generalized additive models (GAMs) to describe habitat associations of Alewife, Blueback Herring, Atlantic Herring, and Atlantic Mackerel. Bottom temperature, bottom depth, bottom salinity, solar azimuth and elevation, and region of the Northeast U.S. continental shelf were all significant in the habitat models; GAMs explained 25.2, 16.9, 18.9, and 20.6% of the deviance observed for the presence/absence of Alewife, Blueback Herring, Atlantic Herring, and Atlantic Mackerel. A subset of the data was omitted from the model and the probability of presence was compared with observations; 66-77% of observations were correctly predicted. The individual probabilities of presence were used to quantify and evaluate the accuracy of modelled overlap of Alewife and Blueback Herring with Atlantic Herring (68–72% correct predictions) and Alewife and Blueback Herring with Atlantic Mackerel (57-69% correct predictions). Our findings indicate that environmental gradients influence the distributions and overlap of Alewife, Blueback Herring, Atlantic Herring, and Atlantic Mackerel, and with further testing and refinement these models could be developed into a tool to aid industry in reducing incidental catches of river herring. [ABSTRACT FROM AUTHOR]

Anadromous fishes are commonly thought to use inland waters for spawning and for rearing in the first growing season. Thereafter, they emigrate seaward to feed, grow, and mature. However, yearling (age 1+) alosine herrings have been observed in the Hudson River estuary during the spawning season. We quantified the frequency of this behavior for Blueback Herring ( Alosa aestivalis) in two contrasting time periods: the 1980s-1990s, a period of relatively high abundance, and 2012-2013, a period of low abundance. Using otolith chemistry, we (1) assayed whether yearlings captured during the spawning run had egressed to sea and then returned to fresh water, and (2) examined adult spawners and retrospectively estimated the frequency of yearling returns to fresh water in these recruited fish. At least 36 % and up to 90 % of yearlings showed evidence of overwintering at sea or very far down the estuary prior to returning to fresh water with the spawning adults. Of the adults, 67-75 % showed evidence of returns up to fresh water as yearlings, despite large changes in population size and demographic characteristics. We conclude that this cryptic, 'non-textbook' migratory behavior is common, and suggest that the importance of estuarine and freshwater nurseries may extend beyond the young-of-year period. [ABSTRACT FROM AUTHOR]

Bycatch of mid-trophic-level anadromous fishes that connect marine and freshwater ecosystems is a growing conservation concern. Anadromous alewife ( Alosa pseudoharengus) and blueback herring ( Alosa aestivalis) are important components of coastal freshwater and marine food webs, but have experienced dramatic declines in the abundances of spawning adults. Freshwater-focused restoration efforts have yielded few consistent signs of recovery, raising concerns that bycatch in Northwest Atlantic commercial fisheries may be negating these conservation actions. Using data from 15 microsatellites genotyped for baseline populations and bycatch, we conducted genetic stock identification to understand how bycatch was partitioned among previously identified regional genetic stocks. We then combined this information with fishery observer data to estimate genetic stock-specific bycatch mortality for the southern New England Atlantic herring fishery (2012-2013). Bycatch overall, but especially in the Atlantic herring fishery, was disproportionately assigned to the most severely depleted genetic stocks (alewife southern New England stock - 70% of assignments; blueback herring mid-Atlantic stock - 78% of assignments). These genetic stocks overlap in the region surrounding Long Island Sound, suggesting that bycatch taken from this area in recent years may be negatively impacting recovery efforts in this region. Our study suggests that mitigating bycatch on the southern New England fishing grounds may benefit recovery efforts for alewife and blueback herring genetic stocks that have experienced the greatest declines in spawning adult abundances. [ABSTRACT FROM AUTHOR]

River herring (Alewives; Alosa pseudoharengus and Blueback Herring; Alosa aestivalis) populations have undergone dramatic declines in recent years. Although the exact causes for these population declines are unclear, evidence suggests that factors such as habitat loss and dam construction may prevent upstream migration to spawning grounds, resulting in river herring spawning below the head of tide. As below the head of tide spawning may prematurely expose river herring embryos and larvae to saline environments, a series of experiments were conducted to determine the effect of elevated salinity on embryonic and larval survival. Embryos of both species were acutely exposed to salinities of 2, 5, 10, 15, 20, 25, and 30 g/L as well as to simulated tidal salinity fluctuations, and survival was assessed. Larvae (1-8 days post hatch; DPH) were acutely transferred to 2.5-30 g/L water, and survival was assessed after 24 h. Larvae (0-12 DPH) were also gradually acclimated to salinities ranging from 2.5-30 g/L, and survival assessed 24 h post exposure. Embryonic alewife survival was high (>97%) at salinities ≤10 g/L while blueback herring embryos displayed a wide salinity tolerance throughout the range. Embryos of both species exhibited high survival in tidal salinity exposures. Survival of acutely-transferred alewife and blueback herring larvae decreased with increasing salinity (>20 g/L). Both species were tolerant of high salinity conditions by 15 DPH. These experiments demonstrate that survival of river herring embryos and larvae may be possible in tidally-influenced areas, depending on the developmental stage and rate of salinity exposure. [ABSTRACT FROM AUTHOR]

The abundance of alewife ( Alosa pseudoharengus) and blueback herring ( Alosa aestivalis) has declined throughout their range, and there are increasing concerns about their conservation status. Because of their diadromous life history, variability in rates of survival in fresh water can affect overall recruitment. The objective of our study was to assess how river temperature and flow influence young of the year (YOY) river herring recruitment in the Northeast US. Observations of adult and juvenile fish in five rivers were used to construct spawner-YOY recruits models; these rivers were chosen because of the length of the time series (>15 years) and the paired observations of spawners and juveniles. An environmentally explicit stock-recruitment model explained a substantial fraction (41% to 80%) of the variance in YOY abundance, depending on river system. Our approach allowed for a preliminary discussion of potential mechanisms, which need to be further substantiated by focused field and laboratory studies. Early summer river flow and river temperature had the greatest influence, indicating the importance of conditions in nursery habitats. In certain systems, spring or fall conditions were also important determinants of survival, suggesting additional effects of the environment on spawning of adults and juvenile egress from freshwater nursery habitats. [ABSTRACT FROM AUTHOR]

Understanding the location and duration of habitat use by young fish is important for management and restoration efforts, but is largely unknown in anadromous species. We used otolith microchemistry and ambient water concentrations of Ca, Ba, Mn, and Sr to identify habitat use in the first year of growth for 131 returning adult blueback herring ( Alosa aestivalis) collected in seven spawning runs along the coast of Maine, USA. Ambient Sr:Ca ratios were correlated with salinity and were used as primary indicators of habitat use. Results revealed variable individual migration histories with several discrete migratory patterns; some fish migrated into seawater well before the end of the first year, while the majority exhibited longer residency in freshwater or low salinity habitat. Total area of available habitats ranged from approximately 213 to 6053 ha fresh water and 204 to 3395 ha estuary. Residency in freshwater or low salinity habitats was positively correlated with extent of freshwater habitat ( r = 0.37, P < 0.001). Results emphasize the importance of conserving a variety of habitat types to maintain variation in life histories and ensure plasticity in migratory behavior of diadromous species. [ABSTRACT FROM AUTHOR]

Precipitous declines in wild populations of river herring species (AlewivesAlosa pseudoharengusand Blueback HerringA. aestivalis) have led to increased interest in stock enhancement efforts. Additionally, their popularity as a baitfish among recreational anglers has generated interest in commercial production of these species for marine baitfish markets. The objective of this investigation was to elucidate practical culture protocols for captive propagation of these species for commercial and restoration purposes. Wild Blueback Herring, captured during their annual spawning migration, spawned in tanks volitionally, while Alewives required exogenous hormone administration. Larvae of both species were successfully raised through metamorphosis using a feeding regime comprised of enriched rotifers followed byArtemianauplii and a commercially available diet. Survival of early larvae acclimated to salinities ranging from 5‰ to 15‰ was high for both species (>94.0%) while that for older larvae acclimated to 15, 20, and 30‰ ranged from 64.7% to 95.3%. Juveniles raised at varying salinities (0–30‰) exhibited high survival (95.6–100.0%) and excellent feed conversion ratios (≤1.31) in all treatments. In acute salinity transfer experiments, high survival was observed when fish of both species (233–275 d posthatch) were transferred from low to high salinities, but low survival (10.0% and 3.3%) was observed in Alewives transferred from 15‰ or 30‰ to freshwater (0‰). A nodular fibrotic growth was found on 3.7% and 10.1% of the cultured Alewives and Blueback Herring (≥231 d posthatch), respectively, that likely followed tissue trauma and ulceration. The results of these studies provide a framework for river herring culture in recirculating systems. Received October 30, 2014; accepted January 12, 2015 [ABSTRACT FROM PUBLISHER]

The objectives of this work were to quantify the spatial and temporal distribution of the occurrence of anadromous fishes (alewife Alosa pseudoharengus, blueback herring Alosa aestivalis and American shad Alosa sapidissima) in the stomachs of demersal fishes in coastal waters of the north-west Atlantic Ocean. Results show that anadromous fishes were detectable and quantifiable in the diets of common marine piscivores for every season sampled. Even though anadromous fishes were not the most abundant prey, they accounted for c. 5-10% of the diet by mass for several marine piscivores. Statistical comparisons of these data with fish diet data from a broad-scale survey of the north-west Atlantic Ocean indicate that the frequency of this trophic interaction was significantly higher within spatially and temporally focused sampling areas of this study than in the broad-scale survey. Odds ratios of anadromous predation were as much as 460 times higher in the targeted sampling as compared with the broad-scale sampling. Analyses indicate that anadromous prey consumption was more concentrated in the near-coastal waters compared with consumption of a similar, but more widely distributed species, the Atlantic herring Clupea harengus. In the context of ecosystem-based fisheries management, the results suggest that even low-frequency feeding events may be locally important, and should be incorporated into ecosystem models. [ABSTRACT FROM AUTHOR]

We compared the accuracy of different combinations of natural markers, specifically otolith elemental (Sr:Ca and Ba:Ca) and isotopic ratios (87:86Sr) with and without genetic stock constraints to evaluate their ability to distinguish among anadromous river herring (i.e., alewife, Alosa pseudoharengus, and blueback herring, Alosa aestivalis) populations from their US ranges. Model accuracy increased when constrained to a regional level by genetic stocks. Both species were misclassified to sites up to 1000 km from their collection location when only otolith chemistry was used. The inclusion of genetic constraints improved reclassification rates, and the longer time scale of genetic variation makes this method less sensitive to interannual variation. We recommend the combined approach of otolith chemistry and genetics as a means to trace river herring in marine bycatch back to river of origin. [ABSTRACT FROM AUTHOR]

Populations of Blueback HerringAlosa aestivalis, an important anadromous forage fish in the northeastern USA, have declined from historic levels. Measures to reduce mortality from many sources, including entrainment by hydroelectric turbines, are cited by fishery managers to be important to restoring populations. At the Crescent Hydroelectric Project (Crescent) on the Mohawk River, New York, pulsed ultrasound (122–128 kHz) was used to deter adult and juvenile Blueback Herring migrating out to sea from entering the intake channel to the headrace and turbines, where mortality may occur. To increase the deterrence rate, the sound field was extended further upriver to expose juvenile Blueback Herring to an increasing sound gradient as they migrate downriver and allow them more time to avoid the intake channel. When juvenile Blueback Herring were present upstream of Crescent and exposed to an ultrasound field, mean catch per unit effort (CPUE) by pelagic trawling in the main channel downriver of the ultrasound was 94% of the mean CPUE in the upriver trawl region and 250% of the mean CPUE in the intake channel. Repeated mobile echo sounder surveys revealed that the abundance of juvenile Blueback Herring averaged 35 times higher in the downriver main channel region than in the intake channel region. During the peak migration period of September 20 through October 14, 2012, continuous fixed-location horizontal echo sounding showed the percentage of net downstream passage of juvenile Blueback Herring that bypassed the intake channel significantly increased from 31.1% to 76.5% after redirecting the ultrasonic field upriver. These results demonstrate that pulsed ultrasound, when properly directed, can be used effectively as a fish deterrent system to provide safe downstream passage of juvenile Blueback Herring at hydropower dams. At Crescent, this could increase annual survival by tens of thousands of fish or more. Received October 4, 2013; accepted August 26, 2014 [ABSTRACT FROM AUTHOR]

Alewife ( Alosa pseudoharengus) and blueback herring ( Alosa aestivalis), also known collectively as either river herring or gaspereau, are anadromous clupeid fishes that display spatiotemporal overlap during riverine spawning migrations. Both species have experienced severe population declines within portions of their ranges. Evidence that they home to their natal rivers to spawn suggests the likelihood of ecologically significant population structure, yet this hypothesis has not been rigorously tested. We examined genetic diversity, differentiation and population structure in 34 alewife and four blueback herring populations spanning a 2,500 km portion of their northern range, using 14 microsatellite loci. Significant differentiation was detected among most rivers, and eight genetically defined alewife population clusters that largely corresponded to hydrographic regions were identified. Similar population structure was seen for blueback herring. Genetic isolation by distance was not significant among alewife populations in regions that have been historically influenced by dams, and/or stock transfers, but was highly significant in two regions that have not been subject to these influences. Genetic differentiation of alewife populations was strongest in the Bay of Fundy. Bottleneck tests revealed evidence of demographic bottlenecks in all of the alewife populations. Lastly, our results indicated that hybridization between alewife and blueback herring is common. [ABSTRACT FROM AUTHOR]

The bycatch of river herring (Alosa pseudoharengus and A. aestivalis) and American shad (A. sapidissima) by midwater trawl vessels targeting Atlantic herring (Clupea harengus) and Atlantic mackerel (Scomber scombrus) has become a possible threat to their conservation. Most bycatch occurs during winter when the regional distributions of these five species overlap. The life histories and habits of these species suggest that there are times and areas during winter where overlap is low and bycatch could be reduced. This study identified environmental conditions associated with the presence of river herring and American shad during winter in the US Mid-Atlantic area by testing the hypothesis that fish were detected in an equal proportion to the amount of samples taken within an environmental condition. River herring were associated with colder temperatures and relatively shallow depths, while American shad appeared to be associated with a broader habitat. To determine whether these associations could be used to reduce bycatch, the proportion of effort and catch of target and bycatch species under the conditions associated with bycatch species presence was quantified in a fishery-dependent dataset. Targeting Atlantic mackerel in waters with surface temperatures above 6°C appeared to be the most effective advice for reducing river herring bycatch. [ABSTRACT FROM PUBLISHER]

River herring (alewife, Alosa pseudoharengus, and blueback herring, Alosa aestivalis) are anadromous alosines that play important ecological roles and comprised major US fisheries in the past. Stocks are at historically low levels Atlantic coast-wide and river herring are being considered for listing as threatened species under the Endangered Species Act. A comprehensive, linked freshwater and marine approach to restoring these important species is proposed, informed by a “life cycle” strategy for the recovery of an Endangered Pacific salmon species. The California coho salmon strategy entails identifying core populations stratified by biological units, assessing threats and developing site-specific and range-wide recovery actions to restore habitat and abate threats to all life stages. Protecting and strengthening core populations, combined with marine strategies, is likely key to the recovery of the species at scale. A case study is presented from the Taunton River, a ∼1300-km2 watershed in Massachusetts (USA) that hosts one of the largest river herring runs in New England. This watershed and its river herring populations possess multiple characteristics that indicate resilience and thus it could be an example of a river herring core habitat, critical for the recovery of the species at scale. A watershed-wide protection and restoration initiative is underway. Site-based strategies including dam removal, low impact development retrofits, and land protection are linked to policy efforts such as establishing streamflow standards and easing permitting of restoration projects to protect and improve connectivity, flow, and water quality. These watershed-based strategies are linked to regional scale research and fisheries management to set sustainable directed harvest targets and reduce the bycatch of river herring in ocean fisheries. Core habitats for river herring need to be identified range-wide and investments in those places prioritized to secure resilient source populations. [ABSTRACT FROM PUBLISHER]

Most evidence for hybrid swarm formation stemming from anthropogenic habitat disturbance comes from the breakdown of reproductive isolation between incipient species, or introgression between allopatric species following secondary contact. Human impacts on hybridization between divergent species that naturally occur in sympatry have received considerably less attention. Theory predicts that reinforcement should act to preserve reproductive isolation under such circumstances, potentially making reproductive barriers resistant to human habitat alteration. Using 15 microsatellites, we examined hybridization between sympatric populations of alewife ( Alosa pseudoharengus) and blueback herring ( A. aestivalis) to test whether the frequency of hybridization and pattern of introgression have been impacted by the construction of a dam that isolated formerly anadromous populations of both species in a landlocked freshwater reservoir. The frequency of hybridization and pattern of introgression differed markedly between anadromous and landlocked populations. The rangewide frequency of hybridization among anadromous populations was generally 0-8%, whereas all landlocked individuals were hybrids. Although neutral introgression was observed among anadromous hybrids, directional introgression leading to increased prevalence of alewife genotypes was detected among landlocked hybrids. We demonstrate that habitat alteration can lead to hybrid swarm formation between divergent species that naturally occur sympatrically, and provide empirical evidence that reinforcement does not always sustain reproductive isolation under such circumstances. [ABSTRACT FROM AUTHOR]

A major challenge in conservation biology is the need to broadly prioritize conservation efforts when demographic data are limited. One method to address this challenge is to use population genetic data to define groups of populations linked by migration and then use demographic information from monitored populations to draw inferences about the status of unmonitored populations within those groups. We applied this method to anadromous alewife (Alosa pseudoharengus) and blueback herring (Alosa aestivalis), species for which long-term demographic data are limited. Recent decades have seen dramatic declines in these species, which are an important ecological component of coastal ecosystems and once represented an important fishery resource. Results show that most populations comprise genetically distinguishable units, which are nested geographically within genetically distinct clusters or stocks. We identified three distinct stocks in alewife and four stocks in blueback herring. Analysis of available time series data for spawning adult abundance and body size indicate declines across the US ranges of both species, with the most severe declines having occurred for populations belonging to the Southern New England and the Mid-Atlantic Stocks. While all alewife and blueback herring populations deserve conservation attention, those belonging to these genetic stocks warrant the highest conservation prioritization. [ABSTRACT FROM AUTHOR]

This paper takes water quality as an ethnographic subject. It looks at how water quality monitors in Boston make sense of the quality of water through mundane engagement with three non-human beings who they encounter during their monitoring activities: herring, bacteria and water lily. Each of these organisms suggests a different understanding of water quality for the monitors and poses a dilemma. Water quality monitors who contribute to the production of water quality data come to know water quality as through direct interactions with these beings, mediated by both sensorial experience and laboratory data. These experiences, at the same time, confuse and redraw relationships between science, water flows, non-human vitality, including that of invasive species, and people. [ABSTRACT FROM AUTHOR]

Abstract: River herring, which comprise two species of anadromous alosines (alewife, Alosa pseudoharengus, and blueback herring, Alosa aestivalis), are under consideration for listing under the US Endangered Species Act. River herring populations have not rebounded despite reductions in directed fishing on these species and improvements in their freshwater and estuarine habitats. We examined recent (2005–2009) spatial and temporal patterns of fishing effort in the US fishery for Atlantic herring, Clupea harengus, and river herring bycatch patterns in this fishery. During the year, Atlantic herring fishing activity shifts spatially and temporally from the Northern Mid-Atlantic Bight and Southern New England waters in January–February, to Southern New England waters in March–April, to the Gulf of Maine in May–June, expanding to the Gulf of Maine and Georges Bank in July–August and September–October, respectively, and then contracting to the Gulf of Maine and Southern New England waters in November–December. At-sea fisheries observer data indicate that river herring bycatches in the Atlantic herring fishery occur mostly during January–April and September–December, primarily in Southern New England and the Northern Mid-Atlantic Bight waters. We discuss possible management measure to reduce these bycatches. Similar size, shape, and schooling behaviors between river herring and other pelagic species—and the high volume nature of the Atlantic herring fishery—limit the potential efficacy of gear-based bycatch mitigation measures. Hence, approaches such as regulatory management measures (e.g., time–area closures and catch caps) and improved fleet communication strategies (e.g., “move-on” rules) may be more practical and effective in minimizing river herring bycatch in the Atlantic herring fishery. [Copyright &y& Elsevier]

The erection of dams alters habitat and longitudinal stream connectivity for migratory diadromous and potamodromous fish species and interrupts much of organismal exchange between freshwater and marine ecosystems. In the US, this disruption began with colonial settlement in the seventeenth century but little quantitative assessment of historical impact on accessible habitat and population size has been conducted. We used published surveys, GIS layers and historical documents to create a database of 1356 dams, which was then analyzed to determine the historical timeline of construction, use and resultant fragmentation of watersheds in Maine, US. Historical information on the anadromous river herring was used to determine natural upstream boundaries to migration and establish total potential alewife spawning habitat in nine watersheds with historic populations. Dams in Maine were constructed beginning in 1634 and by 1850 had reduced accessible lake area to less than 5% of the virgin 892 km habitat and 20% of virgin stream habitat. There is a near total loss of accessible habitat by 1860 that followed a west-east pattern of European migration and settlement. Understanding historic trends allows current restoration targets to be assessed and prioritized within an ecosystem-based perspective and may inform expectations for future management of oceanic and freshwater living resources. [ABSTRACT FROM AUTHOR]

Characterization of riverine spawning habitat is important lot the management and restoration of anadromous alosines. We examined the relative effectiveness of oblique plankton lows and spawning pads for collecting the eggs of American shad Alosa sapidissima, hickory shad A. mediocris, and "river herring" la collective term for alewife A. pseudoharengus and blueback herring A. aestivalis) in the Roanoke River, North Carolina. Relatively nonadhesive American shad eggs were only collected by plankton lows, whereas semiadhesive hickory shad and river herring eggs were collected by both methods. Compared with spawning pads, oblique plankton tows had higher probabilities of collecting eggs and led to the identification of longer spawning periods. In assumed spawning areas, twice-weekly plankton sampling for 15 min throughout the spawning season had a 95% or greater probability of collecting at least one egg for all alosines; however, the probabilities were lower in areas with more limited spawning. Comparisons of plankton tows, spawning pads, and two other methods of identifying spawning habitat (direct observation of spawning and examination of female histology) suggested differences in effectiveness and efficiency. Riverwide information on spawning sites and timing for all alosines is most efficiently obtained by plankton sampling. Spawning pads and direct observations of spawning are the best ways to determine microhabitat selectivity for appropriate species, especially when spawning sites have previously been identified. Histological examination can help determine primary spawning sites but is most useful when information on reproductive biology and spawning periodicity is also desired. The target species, riverine habitat conditions, and research goals should be considered when selecting methods with which to evaluate alosine spawning habitat. [ABSTRACT FROM AUTHOR]

Telemetry is a potential approach for assessing how effectively ultrasound steers blueback herring Alosa aestivalis away from undesirable locations. The objectives of this study were to determine (1) whether gastric implantation of radio tags prevented adult blueback herring from reacting to ultrasound and (2) if not, whether radio tag implantation diminished the fish's escape reactions. Eight groups, each consisting of four blueback herring in good condition, were exposed in a circular tank to a single pulse of broadband ultrasound eight times; each time was considered a trial. Radio tags were gastrically implanted in blueback herring from four of the groups. The four untagged groups were used to confirm that blueback herring would react to ultrasound in the tank, while the four tagged groups were used to determine whether tagging prevented a reaction. These reactions were confirmed by measuring the swimming speed immediately before and after a pulse of sound. Blueback herring in both the tagged and untagged groups swam significantly faster after a pulse of sound compared with before the sound pulse. Three of the tagged groups were compared to three of the untagged groups (tested at similar sound pressure levels) to determine whether tagging diminished escape reactions. The escape reaction metrics were the percentage of fish that moved away from the sound source, the percentage that exhibited a C-start (a sudden, high-energy swimming burst used by fish to avoid attacks by predators), and the standardized difference in swimming speeds measured immediately before and after a pulse of sound. There was no significant difference in the escape reactions of tagged and untagged blueback herring. These results suggest that telemetry can be used to assess how effectively ultrasound steers blueback herring away from undesirable locations. [ABSTRACT FROM AUTHOR]

Anadromous river herring (alewives Alosa pseudoharengus and blueback herring A. aestivalis), which constitute a historically and ecologically important component of coastal rivers, have declined precipitously throughout the Atlantic seaboard. Suggested causes of river herring decline include commercial fishing and predation by striped bass Morone saxatilis. Although the causes of this recent trend are poorly understood, river herring are especially vulnerable to adverse impacts during their spring spawning migration. Radiotelemetry is an especially useful method for addressing potential problems encountered during the movement of these fish from the ocean to freshwater. In spite of frequent calls for evaluation of telemetry methods, controlled tests of posttagging effects are rare for alosids and virtually nonexistent for anadromous river herring. We developed a protocol for gastric tagging of anadromous river herring, and we used hatchery and field studies to evaluate behavior, tag placement, stress response, and posttagging mortality. We also compared tagger effects and quantified posttagging upstream movements of fish in the field. In controlled hatchery trials, no fish died at 10 min, 1 h, or 14 d posttagging. No tags were rejected, and only 1 of 35 tags ruptured the gut. In field cages, mortality, plasma cortisol, glucose, and chloride measured at 24 h were similar between tagged and untagged fish. In the field, 12 of 14 fish moved upriver after tagging and spent 114 h on average at upriver sites. Using a variety of approaches, we found no evidence that our tagging protocol adversely affected river herring in comparison with untagged fish that were subjected only to handling and holding. Our protocol, evaluated by comparing responses of tagged and untagged fish under controlled conditions, may be useful in future studies that seek to understand causes of decline for anadromous river herring. [ABSTRACT FROM AUTHOR]

River herring are recognized as a keystone species, and efforts for restoration of their habitats have been advanced across New England. The Passamaquoddy, a native tribe with close ties to river herring, refers to the species as "the fish that feeds all" because of its importance in the food web. These small diadromous fish are also food sources for humans, and are used as bait for other fisheries. One of the biggest threats to river herring survival is dammed rivers, which prevents river herring from reaching their spawning grounds. A new effort seeks to bring together researchers, state and federal managers, and community members with an invested interest in river herring restoration, with the stated goal of improving communication among the parties. Researchers use new technologies such as eDNA to determine the presence of river herring through water samples; many towns collect data through fish counts and scale sampling; and managers use available data to ensure compliance with management goals. A recent meeting affirmed communication gaps, and revealed that among research organizations, there is a lack of transparency regarding research projects and limited access to data or information. It was also evident that citizen participation is an important aspect of river herring restoration and that integration of local knowledge and research capacity into programs would improve outcomes. Community input into the design of research projects could help address local interests and concerns. Participants from all groups agreed a collaborative approach would improve restoration. [ABSTRACT FROM AUTHOR]

Dams within the Susquehanna River drainage, Pennsylvania, are potential barriers to migration of diadromous fishes, and many are under consideration for removal to facilitate fish passage. To provide useful input for prioritizing dam removal, we examined relations between landscape-scale factors and habitat suitability indices (HSIs) for native diadromous species of the Susquehanna River. We used two different methods (U.S. Fish and Wildlife Service method: Stier and Crance [1985], Ross et al. [1993a, 1993b, 1997], and Pardue [1983]; Pennsylvania State University method: Carline et al. [1994]) to calculate HSIs for several life stages of American shad Alosa sapidissima, alewives Alosa pseudoharengus, and blueback herring Alosa aestivalis and a single HSI for American eels Anguilla rostrata based on habitat variables measured at transects spaced every 5 km on six major Susquehanna River tributaries. Using geographical information systems, we calculated land use and geologic variables upstream from each transect and associated those data with HSIs calculated at each transect. We then performed canonical correlation analysis to determine how HSIs were linked to geologic and land use factors. Canonical correlation analysis identified the proportion of watershed underlain by carbonate rock as a positive correlate of HSIs for all species and life stages except American eels and juvenile blueback herring. We hypothesize that potential mechanisms linking carbonate rock to habitat suitability include increased productivity and buffering capacity. No other consistent patterns of positive or negative correlation between landscape-scale factors and HSIs were evident. This analysis will be useful for prioritizing removal of dams in the Susquehanna River drainage, because it provides a broad perspective on relationships between habitat suitability for diadromous fishes and easily measured landscape factors. This approach can be applied elsewhere to elucidate relationships between fine- and coarse-scale variables and suitability of habitat for fishes. [ABSTRACT FROM AUTHOR]

Juvenile anadromous river herring (alewives, Alosa pseudoharengus, and blueback herring, Alosa aestivalis) spend 3–7 months in freshwater before migrating to the ocean, often exhibiting waves of early and late migrations. Migratory patterns and associated abiotic and biotic factors were examined for both species migrating in 2003 from Herring River in Bourne, Massachusetts. Migrating herring were grouped into two temporal periods and separated by species. Relationships between abiotic (water temperature, lunar phase, and precipitation) and biotic (size, age, growth rate, and hatch date) factors and the timing of out-migration (transition to seawater) were examined. Blueback herring migration coincided with a sharp decrease in temperature consistent with the time of year. Peaks in alewive migration may reflect adaptive traits maximizing likelihood of survival through seasonal marginal stream habitats and also avoiding lethal water temperatures in winter. Migrating bluebacks exhibited a single migratory period (late September–October) which occurred between the early and late migratory pulses of the alewives. These patterns may also represent distinct migration strategies between early and late migrating alewives and between the two species of river herring. Early migration may be a mechanism by which factors such as competition and low food availability are mitigated. In contrast, environmental conditions during the post hatching time of late migrators may allow for a size maximizing strategy that promotes migration from the nursery area as late as possible. [ABSTRACT FROM AUTHOR]