共查询到20条相似文献，搜索用时 937 毫秒
1.
2.
Juvenile salmonids display highly variable spatial and temporal patterns of early dispersal that are influenced by density‐dependent and density‐independent factors. Although juvenile coho salmon (Oncorhynchus kisutch) movement patterns in streams and their relationship with body mass and growth have been examined in previous studies, most observations were limited to one season or one stream section. In this study, we monitored the movement of juvenile coho salmon throughout their period of residence in a coastal basin to identify prevalent dispersal strategies and their relationships with body mass, growth rates and survival. Our results revealed seasonally and spatially variable movement patterns. Juvenile coho salmon that dispersed to tidally affected reaches soon after emergence remained more mobile and expressed lower site fidelity than those individuals that remained in upper riverine reaches. We did not detect significantly different growth rates between sedentary and mobile individuals. Although a greater proportion of sedentary than mobile fish survived winter to emigrate from the creek in the spring, reach of residence at the onset of winter influenced these survival estimates. Hence, apparent summer‐to‐smolt survival for mobile individuals was greater than for sedentary fish in tidally influenced reaches, whereas in riverine reaches the sedentary strategy seemed to be favoured. Our research identified complex movement patterns that reflect phenotypic and life history variation, and underscores the importance of maintaining diverse freshwater and estuarine habitats that support juvenile coho salmon before marine migration. 相似文献
3.
4.
Imperfect detection associated with sampling gear presents challenges for wildlife inventory and monitoring efforts. We examined occupancy dynamics and habitat use of juvenile coho salmon, Oncorhynchus kisutch, in shallow lake environments over a summer and early fall season in the Knik River area of south central Alaska using models which control for and estimate sampling gear detection efficiency. In addition, we present statements for the probability that observed absences at a survey site or from a survey area (a collection of sites) are true absences given some amount of sampling effort and analysts' beliefs about site occupancy and sampling gear detection efficiency which can be used to guide inventory and monitoring efforts for juvenile salmon or other wildlife and plant species. Occupancy modelling results demonstrate that minnow traps were effective at sampling juvenile coho in shallow lake environments, with a mean probability of detection across the study period of 0.68 (i.e., probability of detecting the presence of juvenile coho given that they are present at a trap site; SE = 0.03). Juvenile coho salmon migrated into shallow water lakes in late summer and early fall, presumably to seek out overwinter habitat. N‐mixture modelling examination of habitat use demonstrated that once in shallow lake environments, juvenile coho were widely distributed across a range of microhabitats, with some evidence for preference for shallower depths and warmer water temperatures. 相似文献
5.
Joshua H. Viers 《水产资源保护:海洋与淡水生态系统》2008,18(2):147-162
- 1. Prevailing freshwater conservation approaches in the USA stem from policy‐based ecosystem management directives, science‐based gap analyses, and legal interpretations of critical habitats. In California, there has been no systematic prioritization of freshwater habitats critical to the persistence of anadromous salmonid populations.
- 2. Anadromous salmonids provide an optimal focal species for conservation prioritization of freshwater habitats in California owing to their flagship, umbrella and keystone status.
- 3. The Navarro River is a key watershed for both Endangered Species Act and Clean Water Act recovery efforts in the state of California. This watershed serves as a case study in the use of iterative discriminant analysis to objectively classify freshwater habitats critical to the persistence of two species of threatened anadromous salmonids, steelhead (Oncorhynchus mykiss) and coho (Oncorhynchus kisutch).
- 4. Riverscape parameters were used initially to define suitable habitat for focal species; subsequent refinement accounted for human disturbance within the watershed. Results from this study identify 22.1 km of riverine habitat critical to the persistence of coho salmon in the Navarro River watershed, which need active conservation or restoration; it also identified an additional 269.4 km of riverine habitat in need of protection for its aquatic habitat values.
6.
Catherine Bradley Suresh Andrew Sethi Joshua Ashline Jonathon Gerken 《Ecology of Freshwater Fish》2017,26(4):695-706
In this study, we examined summer and fall freshwater rearing habitat use by juvenile coho salmon (Oncorhynchus kisutch) in the quickly urbanising Big Lake drainage in south‐central Alaska. Habitat use was assessed by regressing fish count data against habitat survey information across thirty study sites using generalised linear mixed models. Habitat associations were examined by age‐0 and age‐1+ cohorts separately, providing an opportunity to compare habitat use across different juvenile coho salmon life stages during freshwater rearing. Regression results indicated that the age‐0 cohorts were strongly associated with shallow, wide stream reaches with in‐stream vegetation, whereas age‐1+ cohorts were associated with deeper stream reaches. Furthermore, associations between fork length and habitat characteristics suggest cohort‐specific habitat use patterns are distinct from those attributable to fish size. Habitat use information generated from this study is being used to guide optimal fish passage restoration planning in the Big Lake drainage. Evidence for habitat use partitioning by age cohort during freshwater juvenile rearing indicates that pooling age cohorts into a single “juvenile” stage for the purposes of watershed management may mask important habitat use dynamics. 相似文献
7.
HONGSHENG BI RACHEL E. RUPPEL WILLIAM T. PETERSON EDMUNDO CASILLAS 《Fisheries Oceanography》2008,17(6):463-476
We determined the habitat usage and habitat connectivity of juvenile Chinook (Oncorhynchus tshawytscha) and coho (Oncorhynchus kisutch) salmon in continental shelf waters off Washington and Oregon, based on samples collected every June for 9 yr (1998–2006). Habitat usage and connectivity were evaluated using SeaWiFS satellite‐derived chlorophyll a data and water depth. Logistic regression models were developed for both species, and habitats were first classified using a threshold value estimated from a receiver operating characteristic curve. A Bernoulli random process using catch probabilities from observed data, i.e. the frequency of occurrence of a fish divided by the number of times a station was surveyed, was applied to reclassify stations. Zero‐catch probabilities of yearling Chinook and yearling coho salmon decreased with increases in chlorophyll a concentration, and with decreases in water depth. From 1998 to 2006, ～ 47% of stations surveyed were classified as unfavorable habitat for yearling Chinook salmon and ～ 53% for yearling coho salmon. Potentially favorable habitat varied among years and ranged from 9 856 to 15 120 km2 (Chinook) and from 14 800 to 16 736 km2 (coho). For both species, the smallest habitat area occurred in 1998, an El Niño year. Favorable habitats for yearling Chinook salmon were more isolated in 1998 and 2005 than in other years. Both species had larger and more continuous favorable habitat areas along the Washington coast than along the Oregon coast. The favorable habitats were also larger and more continuous nearshore than offshore for both species. Further investigations on large‐scale transport, mesoscale physical features, and prey and predator availability in the study area are necessary to explain the spatial arrangement of juvenile salmon habitats in continental shelf waters. 相似文献
8.
Todd R. Bennett Phil Roni Keith Denton Michael McHenry Raymond Moses 《Ecology of Freshwater Fish》2015,24(2):264-275
The downstream movement of coho salmon fry and parr in the fall, as distinct from the spring migration of smolts, has been well documented across the range of the species. In many cases, these fish overwinter in freshwater, but they sometimes enter marine waters. It has long been assumed that these latter fish did not survive to return as adults and were ‘surplus’ to the stream's carrying capacity. From 2004 to 2010, we passive integrated transponder tagged 25,981 juvenile coho salmon in three streams in Washington State to determine their movement, survival and the contribution of various juvenile life histories to the adult escapement. We detected 86 returning adults, of which 32 originated from fall/winter migrants. Half of these fall/winter migrants spent ~1 year in the marine environment, while the other half spent ~2 years. In addition, the median return date for fall/winter migrants was 16 days later than spring migrants. Our results indicated that traditional methods of spring‐only smolt enumeration may underestimate juvenile survival and total smolt production, and also overestimate spring smolt‐to‐adult return (SAR). These are important considerations for coho salmon life cycle models that assume juvenile coho salmon have a fixed life history or use traditional parr‐to‐smolt and SAR rates. 相似文献
9.
Igor Popov 《水产资源保护:海洋与淡水生态系统》2021,31(11):3319-3325
- Freshwater pearl mussels (family Margaritiferidae) are sensitive to human impact and environmental changes. Large declines in their abundance have prompted studies of distribution and estimations of population densities.
- Iturup Island, a part of Kuril Islands, Russia, is considered to be within the distribution area of freshwater pearl mussels, but this information is based on only two specimens collected several decades ago. Detailed survey of the island is challenging as most of its territory is nearly impassable.
- A preliminary analysis of island rivers was carried out prior to the surveys to discover potential freshwater pearl mussel habitats. Based on previous experience from European Russia, freshwater pearl mussel habitat was expected to occur in rivers flowing out of lowland lakes.
- Live individuals of Margaritifera laevis were found during surveys in one river together with the unionid Beringiana beringiana, which were also found in two other rivers where the predicted habitat occurred. Based on prediction and surveys, the occurrence of freshwater pearl mussels in other rivers of Iturup Island is unlikely.
- Pearl mussels were concentrated in a small section of the Zmeika River with a population of about 100,000 mussels. Present threats to the population include overharvest of host fish masou salmon (Oncorhynchus masou).
- Surveys using similar methods can help to reveal unknown freshwater mussel populations on other Kuril Islands and on the mainland.
10.
11.
- 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.
- 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.
- 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.
- 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.
12.
There is concern that expanding beaver (Castor fiber) populations will negatively impact the important economic, recreational and ecological resources of Atlantic salmon (Salmo salar) and sea trout (Salmo trutta) populations in Europe. We studied how beaver dams influenced habitat, food resources, growth and movement of juvenile Atlantic salmon and trout on three paired beaver-dammed and beaver-free (control) tributaries of important salmon rivers in central Norway. Lotic reaches of beaver-dammed and control sites were similar in habitat and benthic prey abundance, and ponds were small (<3,000 m2). Though few juvenile salmonids were detected in ponds, trout and salmon were present in habitats below and above ponds (comprising 9%–31% and 0%–57% of the fish collected respectively). Trout dominated control sites (79%–99%), but the greatest proportion of Atlantic salmon were upstream of beaver ponds (0%–57%). Growth rates were highly variable, with no differences in growth between lotic reaches of beaver-dammed and control sites. The condition and densities of juvenile salmon and trout were similar in lotic reaches of beaver-dammed and control sites, though one beaver-dammed site with fine sediment had very few juvenile salmonids. Beaver dams did not block the movement of juvenile salmonids or their ability to use upstream habitats. However, the degree of repeated movements and the overall proportion of fish moving varied between beaver-dammed and control sites. The small scale of habitat alteration and the fact that fish were able to move past dams makes it unlikely that beaver dams negatively impact the juvenile stage of salmon or trout populations. 相似文献
13.
Abstract – To evaluate the effects of habitat, foraging strategy (drift vs. limnetic feeding) and internal prey subsidies (downstream transport of invertebrate drift between habitats) on fish production, we measured the growth of juvenile coho salmon confined to enclosures in flowing (pond inlets and outlets) or standing water (centre of pond) habitats in a constructed river side-channel. The effects of habitat and foraging strategy on fish growth were mediated primarily through habitat effects on prey abundance. Invertebrate drift biomass was nearly an order of magnitude higher at pond inlets relative to outlets. Drift-feeding coho in inlet enclosures grew 50% faster than drift-feeding coho at pond outlets or limnetic feeding coho in the centre of ponds, suggesting that elevated drift at inlets was sufficient to account for higher inlet growth rates. Forty per cent of prey biomass in stomachs was terrestrial in origin. These results indicate that, in addition to dependence on external terrestrial subsidies, streams with alternating slow and fast water (i.e., pool-riffle) sequences are also characterised by internal prey subsidies based on transport of drifting invertebrates from refuge habitats (high velocity riffles) to habitats more suitable for drift-feeding predators (e.g., pools), which may result in higher maximum fish growth in systems where internal subsidises are large. Restoration of small streams to maximise productive capacity for pool-rearing salmonids will require a better understanding of the length and interspersion of habitats that maximises both internal prey subsidies and available rearing habitat for juvenile salmon. 相似文献
14.
HONGSHENG BI WILLIAM T. PETERSON JESSE LAMB EDMUNDO CASILLAS 《Fisheries Oceanography》2011,20(2):125-138
Yearling Chinook (Oncorhynchus tshawytscha) and coho salmon (Oncorhynchus kisutch) were sampled concurrently with physical variables (temperature, salinity, depth) and biological variables (chlorophyll a concentration and copepod abundance) along the Washington and Oregon coast in June 1998–2008. Copepod species were divided into four different groups based on their water‐type affinities: cold neritic, subarctic oceanic, warm neritic, and warm oceanic. Generalized linear mixed models were used to quantify the relationship between the abundance of these four different copepod groups and the abundance of juvenile salmon. The relationships between juvenile salmon and different copepod groups were further validated using regression analysis of annual mean juvenile salmon abundance versus the mean abundance of the copepod groups. Yearling Chinook salmon abundance was negatively correlated with warm oceanic copepods, warm neritic copepods, and bottom depth, and positively correlated with cold neritic copepods, subarctic copepods, and chlorophyll a concentration. The selected habitat variables explained 67% of the variation in yearling Chinook abundance. Yearling coho salmon abundance was negatively correlated with warm oceanic copepods, warm neritic copepods, and bottom depth, and positively correlated with temperature. The selected habitat variables explained 40% of the variation in yearling coho abundance. Results suggest that copepod communities can be used to characterize spatio‐temporal patterns of abundance of juvenile salmon, i.e., large‐scale interannual variations in ocean conditions (warm versus cold years) and inshore‐offshore (cross‐shelf) gradients in the abundance of juvenile salmon can be characterized by differences in the abundance of copepod species with various water mass affinities. 相似文献
15.
Daverat F, Martin J, Fablet R, Pécheyran C. Colonisation tactics of three temperate catadromous species, eel Anguilla anguilla, mullet Liza ramada and flounder Plathychtys flesus, revealed by Bayesian multielemental otolith microchemistry approach.Ecology of Freshwater Fish 2011: 20: 42–51. © 2010 John Wiley & Sons A/S Abstract – The colonisation of Gironde (SW France) river catchment by juvenile, eel, Anguilla anguilla, flounder Platychtys flesus and thinlipp mullet Liza ramada was investigated comparatively using Sr:Ca and Ba:Ca composition of otolith. The relation between Sr, Ba and habitat was investigated based on Sr and Ba water composition sampled each month along the estuary‐river gradient. A total of 50 mullets, 30 eels and 47 flounders were collected in the Gironde river catchment. Analysis was performed with a Femtosecond LA‐ICPMS along a trajectory from the core to the edge. Sr and Ba water concentrations discriminated three habitats within the Gironde system, the lower estuary, the upper estuary and the freshwater sites. A signal processing method based on Gaussian hidden Markov models was applied to the multielemental life‐history data. The linear model used to allocate a Gironde habitat to coupled Sr, Ca values was parameterised with seasonal patterns and magnitude of Sr and Ba water values in the different habitats. The results showed that the three species used three different habitats and they had a large diversity of habitat use patterns with resident and nomadic tactics. Resident tactics were less frequent than nomadic tactics that suggested individual fish used two or more habitats. Mullet used a wider range of habitats in the lower part of the estuary than eel and flounder and switched habitats more frequently. Flounders tended to colonise initially freshwater, and then estuarine habitats later in life while mullets used the entire range of available catchment habitats throughout their life. 相似文献
16.
Negative effect of zebra mussels on foraging and habitat use by lake sturgeon (Acipenser fulvescens)
- 1. Lake sturgeon (Acipenser fulvescens) are threatened or endangered throughout much of their range. Juvenile sturgeon utilize sandy and silty habitats extensively during their growth. Invasive zebra mussels change the nature of sandy and silty habitats because they settle on and coat the habitat with the shells of living and dead individuals. The potential impacts of this increased habitat complexity on lake sturgeon is unknown.
- 2. Juvenile lake sturgeon habitat choice was assessed in laboratory experiments, and zebra mussel impact on the foraging success of juvenile lake sturgeon on three different prey species was measured.
- 3. Sturgeon foraging on chironomids was virtually eliminated by 95% zebra mussel cover of the sand floor of the foraging arena, and 50% cover reduced foraging significantly. Foraging on more mobile prey items (amphipods and isopods) was essentially eliminated by either 95% or 50% zebra mussel cover of the arena floor. In habitat choice experiments, sturgeon avoided the zebra‐mussel‐covered habitat more than 90% of the time.
- 4. This combination of zebra mussel avoidance and reduced foraging in the presence of zebra mussels may be detrimental to sturgeon restocking programmes utilizing smaller sturgeon in zebra‐mussel‐infested waterways.
17.
Riparian defoliation by the invasive green alder sawfly influences terrestrial prey subsidies to salmon streams 
下载免费PDF全文
下载免费PDF全文 Invasive species in riparian forests are unique as their effects can transcend ecosystem boundaries via stream‐riparian linkages. The green alder sawfly (Monsoma pulveratum) is an invasive wasp whose larvae are defoliating riparian thin‐leaf alder (Alnus tenuifolia) stands across southcentral Alaska. To test the hypothesis that riparian defoliation by this invasive sawfly negatively affects the flow of terrestrial prey resources to stream fishes, we sampled terrestrial invertebrates on riparian alder foliage, their subsidies to streams and their consumption by juvenile coho salmon (Oncorhynchus kisutch). Invasive sawflies altered the composition of terrestrial invertebrates on riparian alder foliage and as terrestrial prey subsidies to streams. Community analyses supported these findings revealing that invasive sawflies shifted the community structure of terrestrial invertebrates between seasons and levels of energy flow (riparian foliage, streams and fish). Invasive sawfly biomass peaked mid‐summer, altering the timing and magnitude of terrestrial prey subsidies to streams. Contrary to our hypothesis, invasive sawflies had no effect on the biomass of native taxa on riparian alder foliage, as terrestrial prey subsidies, or in juvenile coho salmon diets. Juvenile coho salmon consumed invasive sawflies when most abundant, but relied more on other prey types selecting against sawflies relative to their availability. Although we did not find effects of invasive sawflies extending to juvenile coho salmon in this study, these results could change as the distribution of invasive sawflies expands or as defoliation intensifies. Nevertheless, riparian defoliation by these invasive sawflies is likely having other ecological effects that merits further investigation. 相似文献
18.
We investigated the summer ecology of juvenile steelhead trout Onchorhynchus mykiss and Chinook salmon O. tshawytscha in the context of habitat use and movement behaviour. The study area was a 14.8 km section of the Chehalis River, Washington, and is of particular interest due to recent proposals for both a flood retention dam and restoration actions in this watershed. Ten study reaches were paired in distance upstream and downstream from a central point where a passive integrated transponder antenna array was operated between late June and September 2014. Juvenile densities for each species were associated with reach‐scale habitat and temperature characteristics. Juvenile steelhead underwent upstream and downstream movements up to 7 km, although more fish from further away moved downstream than upstream. Juvenile steelhead repeated horizontal movements throughout the study period, but daily detections were not associated with temperature or flow. The majority (81%) of steelhead movements occurred between the hours of 04:00–07:00 and 18:00–21:00. Juvenile Chinook underwent a downstream migration that was nearly complete by the end of August. Most juvenile Chinook were detected just once and movements occurred on days with warmer stream temperature and higher flows. The majority of Chinook movements occurred at night. Although juvenile salmonids are often thought to have small home ranges during summer months, our results suggest that horizontal movements may be more prevalent than previously thought. Summer habitat should be defined by a network of suitable rearing reaches with connectivity available in both upstream and downstream directions. 相似文献
19.
- Tracking of juvenile sea turtles is a research priority to inform the protection of relevant habitats and ensure sustainable rates of recruitment into adult populations. Based on satellite tracking, mixed stock analysis, and mark–recapture studies, Drini Bay in the South Adriatic Sea, Central Mediterranean, has been confirmed as an important foraging site used by loggerhead turtles from all major rookeries in the Mediterranean subpopulation.
- Three juvenile loggerhead turtles (Caretta caretta) from Drini Bay were tracked for 763, 364, and 211 days respectively. All turtles exhibited different movement patterns.
- The two smaller turtles ranged widely beyond the bay. One of these (69.5 cm curved‐carapace length; CCL) used the coldest region of the Mediterranean during the first winter of tracking where mean weekly temperatures dipped below 12°C but moved southwards to warmer waters during the second winter. In comparison, the other (66 cm CCL) individual moved south to winter in warmer waters from the outset. Both individuals returned to Drini Bay during summer, demonstrating fidelity to the study site. The third turtle, which was larger (76 cm CCL), remained in Drini Bay for the duration of tracking. These results support the findings of other mark–recapture studies at Drini Bay, which have suggested that the foraging site is being used in a transient way by immature turtles.
- All three turtles preferentially used the shallow waters (<30 m) in the south of Drini Bay. The study demonstrates a high degree of overlap between the habitat use of the three tracked turtles and that of adult turtles tracked from nesting sites, and although based on a small sample size, contributes to a growing knowledge base regarding the wider habitat use of the Mediterranean loggerhead population.
20.
Angela H. Arthington Richard G. Pearson Paul C. Godfrey Fazlul Karim Jim Wallace 《水产资源保护:海洋与淡水生态系统》2020,30(9):1727-1733
- The paper ‘Biodiversity values of remnant freshwater floodplain lagoons in agricultural catchments: evidence for fish of the Wet Tropics bioregion, northern Australia’, published in Aquatic Conservation: Marine and Freshwater Ecosystems in 2015, has contributed in several ways to the integration of freshwater wetland science within new catchment management policies and practices for Great Barrier Reef (GBR) sustainability.
- The Tully–Murray biodiversity study developed novel protocols to sample larval, juvenile, and adult fish life‐history stages in floodplain lagoons using a combination of boat‐based backpack electrofishing and fyke netting. In addition, hydrological and hydrodynamic models were applied in a completely new way to quantify the timing, extent, and duration of water connectivity across floodplain streams, cane drains, and wetlands. Combining the two novel approaches enabled an analysis of lagoon fish assemblage patterns in relation to environmental gradients, especially floodplain hydrology, connectivity patterns, and measures related to agricultural land use.
- In demonstrating the importance of different levels of connectivity for different biodiversity outcomes in freshwater floodplain lagoons of the Tully–Murray catchment, the subject paper established that floodplain connectivity needs to be taken into consideration in wetland management practices.
- The timing of the subject publication was fortuitous. It coincided with the preparation of the evidence‐based 2017 Scientific Consensus Statement on land‐based water quality impacts on the GBR. As one of the few freshwater wetland ecology publications for the catchments of the GBR at that time, this paper played an important role in demonstrating freshwater wetland values, fish conservation options, and management imperatives to sustain wetland ecological health and services in GBR catchments.
- By advancing the understanding of factors driving biodiversity patterns, and the importance of connectivity and ecohydrological processes in freshwater floodplain wetlands of the GBR catchment, the Tully–Murray study helped to drive new policy directives for the protection and restoration of catchment, floodplain, and estuary functions, and connectivity, now embedded in the Reef 2050 Long‐Term Sustainability Plan 2018, an overarching strategy for managing the GBR over the next 35 years, and complementary Queensland environmental legislation.