Find research datasets worth reusing

Fig. 3 in Occurrence of a Skin Parasite Argulus coregoni (Branchiura: Argulidae) on Salmonids in Mountain Streams, Central Japan, with Discussion on Its Longitudinal Distribution and Host Utilization in Rivers

Fig. 3. Mountain streams where the salmonids infected with Argulus coregoni were caught in Gifu Prefecture, central Japan. A, Main stream of the upper Maze River (locality 1 in Fig. 2); B, tributary of the Hida River (locality 2); C, tributary of the Tsukechi River (locality 3); D, tributary of the Yoshida River (locality 4); E, main stream of the Itoshiro River (locality 5); F, tributary of the Itoshiro River (locality 5); G, tributary of the Sho River (locality 6); H, main stream of the Gamada River (locality 7).

Fig. 2 in Occurrence of a Skin Parasite Argulus coregoni (Branchiura: Argulidae) on Salmonids in Mountain Streams, Central Japan, with Discussion on Its Longitudinal Distribution and Host Utilization in Rivers

Fig. 2. Map showing the collection localities of salmonids infect- ed with Argulus coregoni (closed circles 1–7) in rivers of Gifu Prefecture, central Japan. The collection localities of ayu, Plecoglossus altivelis altivelis, infected with A. coregoni, are also shown (open triangles 8–11). 1, Upper reaches of the Maze River; 2, tributary of the Hida River; 3, tributary of the Tsukechi River; 4, tributary of the Yoshida River; 5, the Itoshiro River; 6, tributary of the Sho River; 7, the Gamada River; 8, middle reaches of the Maze River; 9, middle reaches of the Shira River; 10. middle reaches of the Nagara River; 11, lower reaches of the Nagara River.

Fig. 1 in Occurrence of a Skin Parasite Argulus coregoni (Branchiura: Argulidae) on Salmonids in Mountain Streams, Central Japan, with Discussion on Its Longitudinal Distribution and Host Utilization in Rivers

Fig. 1. Argulus coregoni, male, NSMT-Cr 30777, from a white-spotted char, Salvelinus leucomaenis, from the Gamada River, Gifu Prefecture, ethanol-preserved specimen, A, Dorsal view; B, ventral view; C, two females infecting a white-spotted char (180 mm FL) near the left pectoral fin (from the Maze River); D, one female infecting a red-spotted masu salmon, Oncorhynchus masou ishikawae (103 mm FL), near the base of the dorsal fin (from a tributary of the Hida River); E, one female (left) and one male (right) infecting a masu salmon, O. m. masou (257 mm FL), near the left pectoral fin (from the Itoshiro River); F, one female infecting a hybrid between white-spotted char and masu salmon (165 mm FL) near the dorsal fin (from the Itoshiro River). Arrowheads indicate individuals of A. coregoni. See Fig. 2 for the locations of the rivers. Scale bars: A, B, 2 mm; C–F, 20 mm.

Fig. 4 in Occurrence of a Skin Parasite Argulus coregoni (Branchiura: Argulidae) on Salmonids in Mountain Streams, Central Japan, with Discussion on Its Longitudinal Distribution and Host Utilization in Rivers

Fig. 4. Distribution of 31 specimens of Argulus coregoni (closed circles) on the host's body surface. A total of 32 specimens of A. coregoni were collected, but the attachment site for one individual was not recorded.

opencc-zeroDec 2016View details →

Data from: Dry season survival of juvenile salmonids in an intermittent coastal stream

We estimated dry season survival of imperiled salmonids in an intermittent coastal stream in California across four years (2009-2012). Our study encompassed two dry and two wet winters allowing us to explore patterns of survival across and within dry seasons with different antecedent precipitation. Apparent survival of age-0+ steelhead trout (Oncorhynchus mykiss) was higher following wet winters compared to dry winters. Moreover, antecedent precipitation was positively correlated with cumulative survival of age-0+ steelhead. Within years, apparent survival of steelhead varied among weeks with a tendency to decrease in the late summer indicating that fish exhibited some resistance to seasonal drought. Additionally, we found a slight but significant survival advantage for age-0+ coho salmon (O. kisutch) compared to equal-aged steelhead. Our results emphasize the influence of antecedent precipitation in driving the survival of imperiled salmonids and highlight that these fishes are somewhat resistant to seasonal drought, at least to a point.

opencc-zeroDec 2018View details →

Data from: Do precipitation extremes drive growth and migration timing of a Pacific salmonid fish in Mediterranean‐climate streams?

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

opencc-zeroFeb 2023View details →

Data from: Contrasting long-term trends in juvenile abundance of a widespread cold-water salmonid along a latitudinal gradient: Effects of climate, stream size and migration strategy

A changing climate reshapes the range distribution of many organisms, and species with relatively low thermal optima, like many salmonids, are increasingly expected to face local population extinctions at lower latitudes. Understanding where and how fast these changes are happening is of pivotal importance for successful mitigation and conservation efforts. We used an extensive electrofishing database to explore temporal trends of brown trout juveniles (Salmo trutta L.) in 218 locations from 174 Swedish streams, over the last 30 years (1991–2020). We hypothesized that 1) declines in abundance have occurred predominately in the warmer, southern regions, while increases have occurred in the colder, northern regions, 2) larger stream sizes may partly offset negative effects of climate, and 3) migrating and resident populations are affected differently by a warming climate. We found that abundance of brown trout juveniles generally declined in warmer regions, especially in smaller streams (≤ 6 m wide), while the abundance increased in colder regions. In larger streams, negative effects of higher temperatures were seemingly buffered, as we found lower rates of decline or even positive trends. The rate of change (i.e. the slopes of the trends in abundance) was more pronounced towards the climate extremes and was on average zero in regions with a normal annual air temperature (average temperature over 30-year period) around 5–6 ºC. Warmer climate had stronger effects on migrating compared to resident populations, suggesting that climate-induced loss of stream connectivity could be an additional factor that hinders recruitment in anadromous populations in a changing climate. Considering predictions of increasing temperatures and frequency of summer droughts, management of cold-water salmonid populations should focus on conserving and restoring riparian vegetation, wetlands, climate and thermal refugia, and habitat integrity overall. Such measures may, however, not suffice for small streams at lower latitudes, unless hydrological connectivity is maintained.

publicJul 2018View details →

Data from: Dry season survival of juvenile salmonids in an intermittent coastal stream

Open the record for dataset details and reuse information.

publicMar 2019View details →

Data from: Do precipitation extremes drive growth and migration timing of a Pacific salmonid fish in Mediterranean‐climate streams?

Open the record for dataset details and reuse information.

publicFeb 2023View details →

Data from: Contrasting long-term trends in juvenile abundance of a widespread cold-water salmonid along a latitudinal gradient: Effects of climate, stream size and migration strategy

Open the record for dataset details and reuse information.

publicJul 2025View details →

Data from: Dispersal of stream salmonids from nests and stocking sites: patterns, variability, and sampling bias

Open the record for dataset details and reuse information.

opencc-zeroDec 2015View details →

Data from: Climate, demography, and zoogeography predict introgression thresholds in Salmonid hybrid zones in Rocky Mountain streams

Among the many threats posed by invasions of nonnative species is introgressive hybridization, which can lead to the genomic extinction of native taxa. This phenomenon is regarded as common and perhaps inevitable among native cutthroat trout and introduced rainbow trout in western North America, despite that these taxa naturally co-occur in some locations. We conducted a synthetic analysis of 13,315 genotyped fish from 558 sites by building logistic regression models using data from geospatial stream databases and from 12 published studies of hybridization to assess whether environmental covariates could explain levels of introgression between westslope cutthroat trout and rainbow trout in the U.S. northern Rocky Mountains. A consensus model performed well (AUC, 0.78–0.86; classification success, 72–82%; 10-fold cross validation, 70–82%) and predicted that rainbow trout introgression was significantly associated with warmer water temperatures, larger streams, proximity to warmer habitats and to recent sources of rainbow trout propagules, presence within the historical range of rainbow trout, and locations further east. Assuming that water temperatures will continue to rise in response to climate change and that levels of introgression outside the historical range of rainbow trout will equilibrate with those inside that range, we applied six scenarios across a 55,234-km stream network that forecast 9.5–74.7% declines in the amount of habitat occupied by westslope cutthroat trout populations of conservation value, but not the wholesale loss of such populations. We conclude that introgression between these taxa is predictably related to environmental conditions, many of which can be manipulated to foster largely genetically intact populations of westslope cutthroat trout and help managers prioritize conservation activities.

opencc-zeroDec 2016View details →

Data from: Territory size decreases minimally with increasing food abundance in stream salmonids: implications for population regulation

How the local density of territorial animals responds to changes in food abundance will depend on the flexibility of territory size. Quantitative estimates of territory size over a broad range of food abundance are relatively rare because of the difficulty of measuring food abundance in the wild. Stream salmonids are an ideal model system for investigating flexibility in territory size, because food abundance can be quantified in the field and manipulated in the laboratory. We conducted a meta-analysis to test whether territory size decreases with increasing food abundance, and a mixed model analysis to test among three competing predictions: with increasing food abundance, territory size will be (1) fixed – the slope of a regression of log territory size vs. log food abundance = 0; (2) flexible and decreasing, as if individuals are defending a fixed amount of food – a slope = -1; and (3) initially compressible, but with an asymptotic minimum size – a slope between 0 and -1. We collected data from 16 studies that manipulated or measured food abundance while monitoring changes in territory size of young-of-the-year salmonids; 10 were experimental laboratory studies, whereas six were observational field studies. Overall, territory size decreased significantly with increasing food abundance; the weighted average correlation coefficient was -0.31. However, the estimated slope of the relationship between log territory size and log food abundance was only -0.23, significantly different from 0, but also significantly shallower than -1. Our estimated slope suggests that attempts to increase the density of territorial salmonids by increasing food abundance and reducing territory size will be inefficient; a 20-fold increase in food abundance would be required to double population density. Our analysis may also have implications for other species with a territorial mosaic social system – i.e. contiguous territories. In these social systems, social inertia will dampen any effects of changes in food abundance on the local density of settlers, compared to non-territorial species or those with non-contiguous territories.

opencc-zeroDec 2014View details →

Data from: Effective number of breeders provides a link between interannual variation in stream flow and individual reproductive contribution in a stream salmonid

The effective number of breeders that give rise to a cohort (Nb) is a promising metric for genetic monitoring of species with overlapping generations; however, more work is needed to understand factors that contribute to variation in this measure in natural populations. We tested hypotheses related to interannual variation in Nb in two long-term studies of brook trout populations. We found no supporting evidence for our initial hypothesis that inline image reflects inline image (defined as the number of adults in a population at the time of reproduction). inline image was stable relative to inline image and did not follow trends in abundance (one stream negative, the other positive). We used stream flow estimates to test the alternative hypothesis that environmental factors constrain Nb. We observed an intermediate optimum autumn stream flow for both inline image (R2 = 0.73, P = 0.02) and full-sibling family evenness (R2 = 0.77, P = 0.01) in one population and a negative correlation between autumn stream flow and full-sib family evenness in the other population (r = −0.95, P = 0.02). Evidence for greater reproductive skew at the lowest and highest autumn flow was consistent with suboptimal conditions at flow extremes. A series of additional tests provided no supporting evidence for a related hypothesis that density-dependent reproductive success was responsible for the lack of relationship between Nb and NC (so-called genetic compensation). This work provides evidence that Nb is a useful metric of population-specific individual reproductive contribution for genetic monitoring across populations and the link we provide between stream flow and Nb could be used to help predict population resilience to environmental change.

publicJul 2018View details →

Data from: Territory size decreases minimally with increasing food abundance in stream salmonids: implications for population regulation

Open the record for dataset details and reuse information.

publicSep 2017View details →

Data from: Climate, demography, and zoogeography predict introgression thresholds in Salmonid hybrid zones in Rocky Mountain streams

Open the record for dataset details and reuse information.