Spring home ranges of white bass in irrigation reservoirs of the Republican River Basin, Nebraska

Abstract –  Fishery biologists have documented small home ranges, relative to available habitat, for many littoral freshwater fishes. Home ranges for pelagic species, such as white bass Morone chrysops , are generally not well described, yet are thought to be large. We studied white bass movement using acoustic telemetry in two irrigation reservoirs of the Republican River basin in south-western Nebraska. Acoustic transmitters were implanted in fall of the previous year and tracking occurred a minimum of once per week throughout spring (mid-March to May) 2007 and 2008. Linear home ranges were calculated from observed locations of individual fish. Twelve of the twenty-seven tagged fish with at least five locations exhibited localised home ranges throughout the spring whereas the remaining fish exhibited home ranges extending across large portions of each reservoir. Home range size was not correlated with fish size or condition.     

A review of ecological models for brown trout: towards a new demogenetic model

Abstract – Ecological models for stream fish range in scale from individual fish to entire populations. They have been used to assess habitat quality and to predict the demographic and genetic responses to management or disturbance. In this paper, we conduct the first comprehensive review and synthesis of the vast body of modelling literature on the brown trout, Salmo trutta L., with the aim of developing the framework for a demogenetic model, i.e., a model integrating both population dynamics and genetics. We use a bibliometric literature review to identify two main categories of models: population ecology (including population dynamics and population genetics) and population distribution (including habitat–hydraulic and spatial distribution). We assess how these models have previously been applied to stream fish, particularly brown trout, and how recent models have begun to integrate them to address two key management and conservation questions: (i) How can we predict fish population responses to management intervention? and (ii) How is the genetic structure of fish populations influenced by landscape characteristics? Because salmonid populations tend to show watershed scale variation in both demographic and genetic traits, we propose that models combining demographic, genetic and spatial data are promising tools for improving their management and conservation. We conclude with a framework for an individual‐based, spatially explicit demogenetic model that we will apply to stream‐dwelling brown trout populations in the near future.     

Seasonal home range estimates and habitat selection of saugeye in a small warmwater impoundment

Abstract Saugeye, a hatchery‐produced hybrid of walleye, Sander vitreus (Mitchill), × sauger, Sander canadense (Griffith & Smith), is commonly stocked by several state fishery management agencies in the United States. Saugeye is a top‐level predator that can restructure fish communities and provide supplemental angling opportunities. However, there are few published studies explaining distributions and habitat selection of saugeye. This study determined seasonal home range estimates and habitat selection of saugeye in a small warmwater impoundment using ultrasonic telemetry. Seasons for this study were defined as winter, spawn, spring, summer and autumn. Mean home range estimates were greatest during spawn when water temperature increased from 7.5 to 15 °C and lowest in winter when water temperature decreased below 7.5 °C. Saugeye selected open water and mid‐water ledge habitat during each season, but rock/gravel shoreline was increasingly selected during winter and spawn. These results corroborate previous studies that suggest saugeye exhibit seasonal variation in distribution and habitat use patterns. Managers should consider distribution and habitat selection trends of saugeye when assessing stocks or determining whether to introduce the species in a small warmwater impoundment.     

Size isn't everything: movements,home range,and habitat preferences of eastern blue gropers (Achoerodus viridis) demonstrate the efficacy of a small marine reserve

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Diel and seasonal utilization of home ranges in a small lake by smallmouth bass (Micropterus dolomieui)

Abstract– Diel and seasonal movements of 9 smallmouth bass were monitored by ultrasonic tracking for 1–1.5 years in a small gravel pit lake in northeastern Illinois. Each fish had several home ranges over the study period. Males established home ranges around a nesting site in May and June. During the summer months, smallmouth bass had diurnal, nocturnal, diurnal and nocturnal home ranges. The fish exhibited 2 types of behavior when they were within their home ranges. They were either motionless, which generally occurred on the nocturnal home ranges, or they swam slowly about their home ranges. Rapid directional swimming movements occurred when fish were swimming across the lake or moving between home ranges. The home ranges were transitory. The average size of the reproductive (male) home range was 0.07 hectare; 0.12 hectare for nocturnal home ranges; 0.18 hectare for diurnal home range; and 0.20 for diurnal-nocturnal home range. Generally, reproductive and nocturnal home ranges were smaller; other types could be as small as these but were often larger. However, there was no significant difference in home range sizes.     

Multiple survey methods reveal greater abundance of endangered pupfish in restored habitats

1. Freshwater organisms inhabiting arid ecosystems are imperilled by human alterations to water-limited landscapes. This is especially true among desert-dwelling cyprinodontid fishes, 90% of which are imperilled by habitat destruction within limited or shrinking ranges. Constructing habitats that mimic natural habitat form and function may provide a tool for species conservation, especially within freshwater protected areas. However, pupfish population assessments within degraded compared with restored habitats are infrequent, and few comparisons among survey methods exist.
2. Density estimates were developed for Endangered Comanche Springs pupfish Cyprinodon elegans throughout altered and restored habitats in a freshwater protected area by using mark–recapture and N-mixture models fitted to data collected using minnow trap and visual count survey methods. This allowed comparison of habitats, survey methods, and statistical methods commonly used to generate population size estimates for imperilled pupfish.
3. Population estimates varied across major habitat types and were largest among habitats constructed to mimic naturally occurring ciénegas. Estimates using visual counts were higher than estimates from minnow traps where water was deeper and where macroalgae cover was highest. N-mixture models generally estimated higher abundances than mark–recapture and were not limited by recapture ability.
4. The results provide strong evidence that restored habitats house greater abundances of pupfish, but survey and statistical methods commonly used to detect these differences have trade-offs in performance according to the habitats surveyed. This work benefits the field of conservation biology by providing guidance for existing and emerging monitoring programmes assessing abundance-based fish responses to habitat improvements.

     

Potential of contemporary evolution to erode fishery benefits from marine reserves

Marine reserves are valued for their ecological role: protecting fish populations from overharvesting while, at the same time, potentially maintaining fisheries yields via recruitment effects (net export of pelagic eggs and larvae) and spillover (net export of post‐settled juveniles and mature fish) across reserve borders. Focussing on the spillover effect, we argue that when fitness of the protected individuals depends on the relative size of their home ranges compared to the reserve size, and home range size is a property of the individuals, rapid local adaptation might occur in favour of individuals with smaller home ranges. Individuals that avoid fishing mortality by spending most of the time inside the reserve limits (i.e. with smaller home ranges) will experience a fitness advantage, whereas individuals that move beyond boundaries (i.e. with larger home ranges) will increase their risk of being harvested by spillover fisheries. We use empirical data on Atlantic cod (Gadus morhua) home ranges within and around a coastal marine reserve in south Norway as a case to illustrate our idea. Broadly, we highlight how protection‐induced selection and contemporary evolution could fundamentally alter our perspective of marine reserve functioning and recommend quantifying behavioural variability and behavioural consistency of protected populations.     

Tracking bowfin with acoustic telemetry: Insight into the ecology of a living fossil

Little is known about the spatial ecology and behaviour of bowfin (Amia calva), despite the fact that it is an important freshwater carnivore, the last living member of the Amiiformes and effectively a living fossil. In the summer of 2013, acoustic telemetry transmitters were surgically implanted in ten bowfin captured in Toronto Harbour on Lake Ontario. Using a stationary acoustic telemetry array that covered most of the 18‐km² harbour, the residency and movement patterns of bowfin were tracked from their release until November 2014. Detected bowfin ranged in size from 562 to 725 mm total length and included six males and three females (one female was not detected). Bowfin showed high site fidelity with most fish detections concentrated in embayments and within the Toronto Islands, areas characterised by relatively high stable water temperatures and submerged vegetative cover. Statistical modelling revealed that bowfin residency was significantly affected by season, body size, site‐specific estimates of vegetative cover and an interaction between body size and season. Bowfin residency increased with vegetative cover and was highest for large fish during the winter and fall months. Despite the overall high site fidelity exhibited by individuals, several bowfin were mobile over the spring and summer months and moved 5.2–12.9 km among telemetry receivers in the inner and outer harbours. The results of this study provide insight into the seasonal habitat preference, home range size and activity level of this unique fish.     

A meta‐analysis of fish behavioural reaction to underwater human presence

In an increasingly anthropic world, humans have profound impacts on the distribution and behaviour of marine fishes. The increased human presence has modified fishes’ antipredator behavioural responses, and consequently flight decisions, as a function of their changed perceptions of risk. Understanding how fish react to human presence can help identify the most vulnerable functional groups/species and estimate impacts caused by human disturbance. Shoal and body size are known to influence fish flight initiation distance (FID; the distance between the predator and prey when the prey begins to escape); however, few studies attempt to test the moderators of these relationships. Here, we present a comprehensive meta‐analysis evaluating FID of fish in response to human presence. Specifically, we investigated six candidate moderators that could influence the relationship between FID with shoal and body size. Our results showed that individual fish size was strongly and positively correlated with FID and the most important moderator that explained the variance in individual body size‐FID relationship was shoaling behaviour. However, and somehow surprisingly, we detected no significant relationship between shoal size and FID. We discuss how these results can inform the development of fish conservation strategies and ultimately assist in the management of marine protected areas.     

Essential Fish Habitat and the Effective Design of Marine Reserves: Application for Marine Ornamental Fishes

Extensive and unregulated harvest of marine ornamental fishes can lead to localized depletion of target species and habitat degradation from inappropriate collecting techniques. One potential solution to these problems is the creation of marine reserves where fishing is prohibited. Marine reserves have been shown to increase fish abundance and protect ecosystems from habitat destruction associated with fishing. If protective areas are to be effective, they must include the diversity of habitats necessary to accommodate the wide range of fish species that are of interest to the marine ornamental fish trade.Fish assemblages with high diversity and abundance are often associated with habitats of high structural complexity. A relationship between fish size and reef complexity suggests the importance of shelter as a refuge for certain fishes in avoiding predation. Many species tend to aggregate to spawn in structurally complex habitats to reduce their risk of predation. Closing of spawning areas during aggregation periods has been shown to be a highly effective management strategy for these species. The limited home ranges and high degree of habitat specificity associated with many marine ornamental fishes should make marine reserves a highly effective strategy for managing these resources.     

Individual movements,home ranges and habitat use by native rheophilic cyprinids and non‐native catfish in a large regulated river

The mobility patterns of two native species, barbel, Barbus barbus (L.) and chub, Squalius cephalus (L.), and of one non‐native fish species, the catfish Silurus glanis (L.), were assessed on a 35.5‐km reach of the Upper Rhône River, a strong flowing river with notable thermal regime alterations. An active acoustic tracking technique adapted to large rivers allowed (1) the identification of longitudinal home ranges, movements and preferred habitat at large scale, and (2) the analysis of the influence of discharge and water temperature on the movement patterns of the fish. The active fish‐tracking system recorded 1,572 fish localisations over 7 months on a weekly basis for 80% of the tagged fish (37 barbel, 23 chub and 13 catfish). Compared with the catfish, barbel and chub showed wider longitudinal home ranges, more movements >1 km and higher interindividual variability. The catfish preferred artificially heated habitats with less morphological diversity. The three species were more often localised in river sections with high density of woody debris. The results suggest that habitat degradation is more damaging for cyprinids in large modified rivers, while the catfish seemed less, impacted.     

Patterns of movement and habitat use by tigerfish (Hydrocynus vittatus) in the Upper Zambezi River (Namibia)

Abstract – During 6 November to 24 December 2000, 23 tigerfish [( Hydrocynus vittatus ), 30–54 cm] were tagged with radio transmitters in the Zambezi River (Namibia) to record habitat utilisation during low, rising and high water levels. The fish were tracked, on average, every fourth day during 23 November to 18 May. Two movement patterns were detected. Approximately 50% of the fish moved <1000 m among tracking surveys, staying within 'defined' home ranges. The remaining fish showed consistent site fidelity for periods, with long distance movements (>1000 m) to new areas among residency periods. Overall, mean distance moved between tracking surveys was 1447 m. Home range size varied among individuals, with a 95% probability of localisation within an average area of 276,978 m². The fish utilised a mean river stretch of 18,836 m (range = 90–71,840). All the fish were recorded in the main stem, and on average, 95% of the fixes were in the main stem during low water. However, the fish used temporary flooded areas to an increasing extent during the rising and high water period, but did not undertake long-distance migrations into the floodplains. Fish were sometimes near vegetation, but were never recorded into or under vegetation.     

湟水流域水生态保护与修复研究

研究湟水流域水生态现状和保护与修复措施,加强湟水流域水生态保护,维持黄河尤其是黄河上游流域及青藏高原和黄土高原-川滇生态屏障生态安全。湟水干流、大通河梯级开发集中,河流纵向连通性遭到严重破坏,且大部分水电站是引水式小水电站,枯水期水电站下游河道脱流现象严重,河流水流连续性及横向连通性遭到破坏,河流生态功能严重下降。根据国家及黄河流域对湟水流域生态保护定位及要求,在湟水流域水生态状况评价及问题识别的基础上,明确各区域(河段)水生态保护目标,提出了湟水上中下游水生态保护与修复总体布局、重要断面生态需水指标及保障措施和重要湿地、重要鱼类栖息地等保护与修复措施体系。     

Biodiversity and rarity distributions of native freshwater fish in an agricultural landscape: the importance of β diversity between and within water‐body types

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Body size evolution and habitat colonization across 100 million years (Late Jurassic–Paleocene) of the actinopterygian evolutionary history

Fishes are characterized by their capacity to occupy all aquatic environments and by their amazing range of size and morphology. While it is known that habitat influenced the diversity dynamics of fish clades, studies on environmental colonization events through the evolutionary history of ray‐finned fishes have yielded conflicting results as to the origin of modern clades and preferential directions of shifts. The effects of habitat over morphological evolution such as body size remain poorly known in vertebrates. However, body size evolution is more frequently addressed in terms of variation through time and numerous studies have demonstrated that successive taxa within a clade tend to increase in size through time (Cope's or Depéret's rule). We use phylogenetic comparative methods on a genus‐level actinopterygian super‐tree based on extant and fossil data covering the Late Jurassic‐Paleogene interval. Results indicate marine ancestry for freshwater lineages and a dominance of colonizations from marine clades towards other habitats. Similar trends in environment occupancy among different ray‐finned clades are explored. Three main trends affecting non‐closely‐related clades are recognized: (i) the freshwater invaders, (ii) the predominantly marine dwellers and (iii) the environmentally labile fishes. Habitat effects on body size evolution are not statistically supported, but most actinopterygian subclades originate from small‐sized ancestors and tend to increase in size in the course of their evolutionary history. This trend is clear for lineages restricted for long periods of time in the same environments, either marine or freshwater, but it is not observed in environmentally labile fish lineages.     

Environmental requirements and heterogeneity of rheophilic fish nursery habitats in European lowland rivers: Current insights and future challenges

The large-scale degradation of riparian ecotones and of the connectivity between rivers and their floodplains has resulted in a drastic decline of rheophilic fish populations in European temperate lowland rivers. Recent river restoration projects have had variable success in effectively restoring these fish populations. Knowledge on nursery habitat requirements is considered essential for effective population restoration. However, a detailed understanding of the role of habitat heterogeneity in young-of-the-year (YOY) fish population development is limited. Therefore, we carried out a synthesis of the available knowledge on nursery habitat requirements of rheophilic fish species found in European temperate lowland rivers (<200 m elevation). From a total of 603 papers, 77 studies with primary information were selected, containing 390 associations between habitat features and YOY fish. As expected, most studies focused on static components of physical riparian habitat. Generally, YOY fish require habitats of shallow depth (<0.5 m), with slow-flowing water (<0.2 m/s), gentle bank slope (<20°), variety in substratum types (fine sand to gravel), relatively warm water and high food availability. Surprisingly, no clear ontogenetic habitat shifts between larvae and juveniles were found, which may be explained by the limited spatial–temporal resolution of most studies. Since 2011, studies on habitat heterogeneity have increased, but few have explicitly assessed its role in relation to movement patterns of YOY fish for nursery success. Therefore, we recommend that future research focuses on fish movement patterns between habitat patches in heterogeneous (river-floodplain) environments, to increase the knowledge base for effective recovery of rheophilic fish populations.     

Distribution and structure of the population of sea lice, Lepeophtheirus salmonis Krøyer, on Atlantic salmon, Salmo salar L., under typical rearing conditions

Abstract. Samples of Atlantic salmon, Salmo salar L., held in sea cages and tanks with running water were examined for presence of sea lice, Lepeophtheirus salmonis. The number of lice, their sex stage (only post-chalimus stages) and location on the fish body were recorded. A new method has been used to express parasitic intensity in fish of different size. Effects of different factors on the degree and character of infestation (structure of the lice population), such as fish size, habitat and chemical treatment, have been studied. Different lice categories have shown different susceptibility to delousing with dichlorvos. Second pre-adults are most susceptible, and males generally more than females. Running water has been found to'flush out'the lice from the fish body. Pre-adults are flushed out easier than adults, and males generally easier than females. Adult males show high tolerance to water of lowered salinity and great mobility manifested in occasional transfer between hosts. The higher activity level of adult males may partly explain a drop in proportion of males after delousing and in running water. Frequency of mating has been found to increase with parasitic intensity.     

A collaborative approach to investigate site fidelity, home range, and homing behavior of cabezon (Scorpaenichthys marmoratus)

Understanding the area use requirements of species targeted for protection by marine protected areas (MPAs) is critical to the future conservation efforts of economically important fish species. Knowledge of home range size and site fidelity is essential in determining whether species will benefit from the protection offered by a MPA, the size of the area needed to protect individuals, and the extent to which surrounding unprotected areas may be supplemented through post-recruitment movement or “spillover”. We utilized a traditional mark and recapture approach, along with GIS spatial analysis to investigate the site fidelity, home range, and homing behavior of the economically important fish species cabezon (Scorpaenichthys marmoratus) on the south central coast of California. In collaboration with members of the commercial live-fish fishery, a total of 1240 sub-adult and adult cabezon were tagged during 10 days of fishing from September to December of 2004 along ∼18 km of coastline. A public awareness and reward program resulted in 330 total recaptures from 290 different individuals (23% recapture rate) with recaptured individuals at liberty up to 1000 days after initial tagging. A majority of individuals displayed high site fidelity, with 81% of recapture events occurring within 100 m of their initial capture locations, and only 9 individuals (.03%) recaptured greater than 1 km. Most individuals (64%) displayed home ranges less than 1000 m². Ten individuals recaptured after experiencing translocation of up to 5.3 km displayed strong homing behavior, returning to within 14 m of their initial capture locations. Findings suggest that under circumstances where suitable habitat is available in nearby unprotected areas, that adult “spillover” will likely be limited to areas within 100 m from MPA boundaries. In addition, the size of the area needed to protect individual cabezon, should be at least 1000 m². Findings from this study demonstrate many of the potential benefits of scientists and fishers working together to investigate area use patterns of economically important fish species to facilitate future design and assessment of MPAs.     

Winter movements of burbot (Lota lota) during an extreme drawdown in Bull Lake, Wyoming, USA

Winter movements of burbot (Lota lota) were monitored in Bull Lake, Wyoming during a record low water storage period in the winter of 1985–1986. Burbot with surgically implanted ultrasonic transmitters were commonly sedentary during the drawdown. The fish that did move were most active during dusk and at night in winter and during the day in spring. Burbot did not appear to occupy well defined home ranges or show discernible movement patterns. Movement into shallow water during winter was attributed to colder water temperatures and the onset of the spawning season. Burbot were always found associated with silt substrates during the drawdown. Aerial photographs of the exposed bottom revealed that virtually all suitable spawning and nursery habitat for burbot was eliminated by the 13.4-m drawdown.     

Stocked rainbow trout (Oncorhynchus mykiss) affect space use by Warpaint Shiners (Luxilus coccogenis)

Due to widespread stocking, Rainbow Trout (Oncorhynchus mykiss Walbaum) are perhaps the most widely distributed invasive species in the world. Nonetheless, little is known about the effects of stocked Rainbow Trout on native non‐game species. We conducted experiments in an artificial stream to assess the effects of hatchery Rainbow Trout on home range and behaviour of Warpaint Shiners (Luxilus coccogenis Cope), a common minnow frequently found in stocked Southern Appalachian streams. We used the LoCoH algorithm to generate polygons describing the home ranges used by Warpaint Shiners. When a stocked trout was present Warpaint Shiners: (a) increased home range size by 57%, (b) were displaced into higher velocity mesohabitats, and (c) reduced mean overlap between the home ranges of individual warpaint shiners. Rainbow Trout did not significantly affect the edge/area ratio of Warpaint Shiner home ranges. Warpaint Shiner density (two and five fish treatments) did not significantly affect any response variable. Displacement from preferred microhabitats and increases in home range size likely result in increased energy expenditure and exposure to potential predators (i.e., decreased individual fitness) of Warpaint Shiners when stocked trout are present.