Article

White Sturgeon Spawning Habitat in an Unregulated River: Fraser River, Canada

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Abstract

Spawning habitat used by white sturgeon Acipenser transmontanus in the lower Fraser River, British Columbia, is described based on field sampling in 1998 and 1999. Fraser River flow is unregulated and, within our study area, its channel morphology is largely unaltered by land use activities. The study area consisted of (1) the wandering reach (river km 98–143), which had side channels, wooded islands, and gravel bars; and (2) the confined reach (river km 145–181), which was naturally restricted by mountains, producing a single-thread and simple channel. Six spawning sites were identified in the study area, five in side channels of the wandering reach and one in the main channel of the confined reach. Within the wandering reach, eggs and larvae were collected only from side channels despite sampling efforts in main-channel areas. Multiple lines of evidence, including radio-tracking of prespawning adults and visual observations, substantiated the use of side channels by white sturgeon for spawning. A total of 3 unfertilized and 80 fertilized eggs were captured at water velocities averaging 1.8 m/s, whereas 101 larvae were found in velocities averaging 1.0 m/s. Water depths averaged 2.9 m at capture locations for all life stages and were shallow compared with depths of egg and larval captures reported from most regulated rivers. Turbidity, which averaged 42 nephelometric turbidity units during the spawning period, was notably higher than in regulated rivers. We hypothesize that reduced light attenuation due to turbidity may substantially influence habitat suitability for spawning within the range of available water depths and velocities. Our observations of white sturgeon spawning activity outside of main-channel habitats are unique, and we have demonstrated that spawning may occur over a wider range of habitat conditions than previously reported. Our observations of white sturgeon spawning in an unregulated river in which fluvial processes and channel morphology are relatively unaltered, albeit increasingly threatened by river engineering, are also unique.

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... Spawning WS appear to be attracted to a particular reach and then likely select areas within the reach for egg deposition based on velocity, depth, substrate composition, turbulence or a combination of these or other factors. Spawning generally occurs in areas with fast-flowing waters over coarse substrates (Parsley et al., 1993;Hildebrand et al., 1999;Parsley and Kappenman, 2000;Perrin et al., 2003). In the Kootenai River, spawning has been observed over clay and/or sand , which is considered as sub-optimal spawning substrate. ...
... Coarse substrates also provide hiding habitat for hatched larval WS. Near-bottom velocities in egg deposition areas are typically >1 m s À1 (Parsley et al., 1993;Perrin et al., 2003;ASL et al., 2007). ...
... Most spawning locations in the lower Fraser River have been identified based on sampling individual years. However, egg detection over multiple years (Perrin et al., 2003;Liebe and Sykes, 2011;Triton, 2013) suggests some locations are repeatedly used. Spawning occurs near peak flows and during the declining hydrograph at water temperatures from 11 to 18°C. ...
Article
White Sturgeon, Acipenser transmontanus (WS), are distributed throughout three major river basins on the West Coast of North America: the Sacramento-San Joaquin, Columbia, and Fraser River drainages. Considered the largest North American freshwater fish, some WS use estuarine habitat and make limited marine movements between river basins. Some populations are listed by the United States or Canada as threatened or endangered (upper Columbia River above Grand Coulee Dam; Kootenai River; lower, middle and, upper Fraser River and Nechako River), while others do not warrant federal listing at this time (Sacramento-San Joaquin Rivers; Columbia River below Grand Coulee Dam; Snake River). Threats that impact WS throughout the species’ range include fishing effects and habitat alteration and degradation. Several populations suffer from recruitment limitations or collapse due to high early life mortality associated with these threats. Efforts to preserve WS populations include annual monitoring, harvest restrictions, habitat restoration, and conservation aquaculture. This paper provides a review of current knowledge on WS life history, ecology, physiology, behavior, and genetics and presents the status of WS in each drainage. Ongoing management and conservation efforts and additional research needs are identified to address present and future risks to the species.
... Knowledge of these areas has been deemed critical to understand the overall abundance of fish populations (Hjort 1914;May 1974;Hempel 1979) and was deemed essential to identify potential impacts of water resource management operations in the upper Sacramento River to the population. Eggs collected on substrate mats have been used to identify spawning areas for a number of North American sturgeon species: Gulf Sturgeon A. oxyrinchus desotoi (Sulak and Clugston 1998;Fox et al. 2000), Shortnose Sturgeon A. brevirostrum (Cooke and Leack 2004;Duncan et al. 2004), Lake Sturgeon A. fulvescens (Caswell et al. 2004;Chiotti et al. 2008), White Sturgeon A. transmontanus (Schaffter 1997;Paragamian et al. 2002;Perrin et al. 2003), and to a limited extent, Green Sturgeon (Brown 2007;Seesholtz et al. 2015). ...
... The wide variation may be explained by temporal and spatial attributes as early spawners in the upper reaches of the river experienced the lowest seasonal temperatures in contrast to late spawners detected in reaches below the RBDD. Schaffter (1997) reported water temperatures for spawning White Sturgeon within the Sacramento River to be between 12 C and 17 C. Perrin et al. (2003) noted water temperatures of 13-19 C (mean D 14.4 C) for White Sturgeon in the Fraser River, British Columbia. They also noted annual increases in temperature in each year of study, in contrast to the temperature-regulated reaches of the upper Sacramento River. ...
... Depths at which Green Sturgeon eggs were collected ranged from 0.6 to 11.3 m (mean § SD D 6.4 § 2.3 m; Figure 4a), which was far less than the maximum depths of 24.0-27.0 m Parsley et al. (1993) and McCabe and Tracy (1994) reported, but slightly greater than that of 4.6-5.1 m found by Schaffter (1997) or Perrin et al. (2003) for White Sturgeon. We note the similarity in spawner preference for the deepest areas within the sample reach as Paragamian et al. (2009) noted for Kootenai River White Sturgeon regardless of absolute value. ...
Article
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Spawning of the Southern Distinct Population Segment of Green Sturgeon Acipenser medirostris occurs annually within the Sacramento River in California. Artificial substrate samplers were used to collect Green Sturgeon eggs between 2008 and 2012 and in a reach of the river 94 river kilometers (rkm) long (rkm 426–332). A total of 268 eggs and 5 posthatch larvae were sampled from seven identified spawning sites between April 2 and July 7, primarily from medium gravel substrates. At these sites the mean water column velocities were 0.8 m/s at depths ranging from 0.6 to 11.3 m (6.4 ± 2.3 m, mean ± SD). We noted an average discharge of 314 m3/s and a median turbidity value of 3.9 NTU during estimated spawning events. Spawning at all sites occurred when average water temperatures were 13.5 ± 1.0°C and during water year types ranging from critically dry to wet. Green Sturgeon eggs averaged 4.11 ± 0.20 mm in diameter (n = 207), were very adhesive, and were between developmental stages 2 (just fertilized) and 44 (posthatch larva). We estimated that eggs were collected from a minimum of 54 different spawning events, based on sample date and location, egg developmental stage at capture, and water temperatures. Green Sturgeon spawning data indicates there is spatial separation from sympatric White Sturgeon A. transmontanus, but some temporal overlap exists. The thermally and hydrologically managed Sacramento River with its numerous diversions and competing water demands appears to have an approximate reach of 120 rkm in the 405-km-long river that is favorable for Green Sturgeon spawning in most years. Management decisions need to assess and incorporate the spawning habitat requirements of Green Sturgeon and coordinate this information with that of endangered winter-run Chinook Salmon Oncorhynchus tshawytscha while attempting to meet the diverse demands of the limited Sacramento River water resources.Received April 20, 2015; accepted June 30, 2015
... White sturgeon, Acipenser transmontanus Richardson, 1836, are native to western North America from Alaska to California (Scott and Crossman, 1998) where their spawning and habitat preferences are well documented (Kohlhorst, 1976;Parsley et al., 1993;Perrin et al., 2003). One of many problems for sturgeon species is population fragmentation and loss of habitat quality caused by dam operations. ...
... White Sturgeon are thought to prefer swift, turbulent water for spawning (Parsley et al., 1993;Schafter, 1997;Perrin et al., 2003). Limited evidence suggests that White Sturgeon may spawn throughout the water column (Parsley et al., 1993;. ...
... The Kootenai River spawning reach differs in habitat from many other rivers, e.g. the lower Columbia (Parsley et al. 1993); upper Columbia (Hildebrand et al., 1999); Fraser (Perrin et al., 2003), despite the fact that it is also a regulated river where flows have been altered and the sediment transport changed (Barton, 2004). The spawning reach within the meander reach is under sluggish backwater conditions (from Kootenay Lake, BC) and the Froude number low, which reflects a river with a low energy state. ...
Article
The objective was to use hydrologic and bathymetric models for the riverscape of the Kootenai River, Idaho, USA and integrate these data with radio telemetry locations of two female white Sturgeon, Acipenser transmontanus Richardson, 1836, during the spawning season. The detailed analysis of habitat features and models provided an enhanced understanding of the habitat preferences of spawning White Sturgeon, which could be used to protect or enhance the habitat. Hydrologic models will also provide a basis to incorporate a larger sample of fish in the future. The White Sturgeon habitats were studied during the 2002 and 2003 spawning seasons. Depth sensitive radio transmitters, geographic positioning systems, single-beam and multibeam echo sounders and multidimensional surface water modeling were used to identify similarities and dissimilarities in the habitat selection of the two monitored female White Sturgeon. The movements of the two fish were not randomly distributed; both fish spent a significant amount of time swimming near the river bottom and thalweg or resting near the river bottom (within 20% of the lower water column [6–9 m]). Mahalanobis distances quantitatively described the similarities between select habitat features of depth, river velocity and riverbed slope at the studied locations and compared the entire spawning reach. The fish occupied sites previously identified as spawning locations. Both fish selected similar depth, median velocity (0.3 m s−1) and bank preferences, avoiding the shallow water on the inside of meander bends and tending to stay in the deeper water on the outside of meanders. They exhibited a tendency to occupy intermediate velocities in parts of the river where the ratio of the velocity at the fish to the maximum velocity in the channel cross-section was >0.25 and <0.75. Some of the differences in habitat selection were likely due to the larger river discharge in 2002 compared to 2003, the length of time each fish was monitored, and the length of the spawning reach occupied by each fish. Some of the differences could, however, have been due to individual preferences. A larger sample size will greatly enhance studies.
... During a recent 8-year study, only 15 white sturgeon eggs were collected over gravel and cobble substrates, while 1,193 eggs were collected over sand substrate . The fine-sediment spawning substrate used by Kootenai River white sturgeon differs considerably from the gravel, cobble, boulder, and [Management Brief] bedrock spawning substrates used by some other white sturgeon populations (Parsley and Beckman 1994;Anders 2002;Perrin et al. 2003). White sturgeon embryos, which are adhesive and demersal, may be buried by aggrading fine sediments in Kootenai River spawning areas characterized by large mobile sand dunes on the river bottom (Paragamian et al. 1998). ...
... In contrast, white sturgeon spawning has been documented in Columbia and Snake River dam tailraces (Parsley et al. 1993(Parsley et al. , 1994Parsley and Kappenman 2000) over bedrock and larger-diameter substrates of boulders, cobble, or gravel in areas of relatively high velocity (!0.8 m/s). In the Fraser River, white sturgeon spawn over gravel and sand substrates (Perrin et al. 2003) in relatively high-velocity side channels (1.3-2.2 m/s). Water temperatures in the Kootenai River during spawning (8.5-12.08C; ) are also several degrees cooler than for several other northwestern white sturgeon populations (10-188C in the lower Columbia River, Parsley et al. 1993; 158C in the Fraser River, Perrin et al. 2003), which would be expected to lengthen the incubation period (and the duration of susceptibility to moving sediments) by several days. ...
... In the Fraser River, white sturgeon spawn over gravel and sand substrates (Perrin et al. 2003) in relatively high-velocity side channels (1.3-2.2 m/s). Water temperatures in the Kootenai River during spawning (8.5-12.08C; ) are also several degrees cooler than for several other northwestern white sturgeon populations (10-188C in the lower Columbia River, Parsley et al. 1993; 158C in the Fraser River, Perrin et al. 2003), which would be expected to lengthen the incubation period (and the duration of susceptibility to moving sediments) by several days. ...
Article
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A simple, inexpensive apparatus (embryo incubation unit (EIU)) was developed and used to assess the relationship between sediment cover (Kootenai River sediments, 97% by weight in the 0.83-mm- to 1.0-mm-diameter range) and survival of white sturgeon Acipenser transmontanus embryos in the laboratory. An apparatus-testing trial assessed the effects of two sediment depths (5 and 20 mm), three EIU ventilation hole sizes (4.8, 6.8, and 9.5 mm) providing three levels of intrasediment flow, and EIU location (upstream or downstream in laboratory troughs) on embryo survival at two above-substrate flow velocities (0.05 and 0.15 m/s). A second trial assessed the effects of sediment cover duration (5-mm sediment cover for 4, 7, 9, 11, or 14 d, with a ventilation hole size of 9.5 mm and a flow velocity of 0.17 m/s) on mean embryo survival and larval length and weight. In the apparatus-testing trial, embryo survival was reduced (P < 0.0001) to 0–5% under sediment covers of either 5 or 20 mm in both the higher-flow and lower-flow troughs; survival in control EIUs without sediments exceeded 80%. Survival was not significantly affected by ventilation hole size but was weakly affected by EIU location. In the second trial, embryo survival was negatively correlated (P = 0.001) with increasing duration of sediment cover and was significantly higher for embryos covered for 4 d (50% survival) or 7 d (30% survival) than for those covered for 9, 11, or 14 d (15–20% survival). Sediment cover also delayed hatch timing (P < 0.0001) and decreased mean larval length (P < 0.0001). Our results suggest that sediment cover may be an important early life stage mortality factor in rivers where white sturgeon spawn over fine-sediment substrates.
... As suggested by other studies, we found egg mats were more effective in determining finescale location (Fox et al. 2000;Paragamian et al. 2001;. We also found plankton nets had a higher catch rate and provided presence information on a broader time scale and with less effort, as suggested by previous work (Auer and Baker 2002;Perrin et al. 2003). The location of egg collections suggest the lock wing wall may be positively selected by spawning shortnose sturgeon. ...
... Wayman, US Fish and Wildlife Service, Warm Springs, Georgia, unpublished data) with rates published for other species. Several studies examining white sturgeon spawning experienced errors of as much as 4 h when backcalculating spawning dates Perrin et al. 2003). Developmental rates were chosen to be conservative, so if errors occurred, we probably underestimated the number of spawning events. ...
... Egg mats captured eggs that were much earlier in development, and the eggs probably attached to the mats during spawning events. In previous studies, newly spawned eggs (Ͻ48 h old) collected on egg mats were indicators of spawning by white and Gulf sturgeon A. oxyrinchus desotoi (Fox et al. 2000;Paragamian et al. 2001;, based on dermersal and adhesive characteristics of sturgeon eggs (Dadswell 1984;Wang et al. 1985;Kempinger 1988;Kynard 1997;Perrin et al. 2003). Over 50% of eggs collected from egg mats could be aged to within 3 h of spawning time. ...
Article
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Fifty egg mats and up to five D-shaped plankton nets were deployed in the tailrace of Pinopolis Dam at river kilometer 77 on the Cooper River, South Carolina, to evaluate the spawning activity of shortnose sturgeon Acipenser brevirostrum. Spawning times were estimated by back-calculation based on developmental phase. Eggs were collected on 17 of 21 d sampled continuously from March 4 through March 25, 2002, when water temperatures were 10–16°C. A total of 31 shortnose sturgeon eggs were collected from egg mats. An additional 338 shortnose sturgeon eggs and 1 newly hatched yolk sac larva were collected from plankton nets. A minimum of 20 spawning events occurred in the tailrace during the 2002 spawning season. No relationship between mean daily discharge and spawning date was observed. Shortnose sturgeon spawned more often during the night than at any other time of day independent of generation.
... Our records are also consistent with previous studies of White Sturgeon in the Sacramento River (Miller 1972;Kohlhorst 1976;Schaffter 1997). The Sacramento River population of White Sturgeon spawns earlier than more northern populations (McCabe Jr and Tracy 1994;Perrin et al. 2003). But, adult White Sturgeon in the Fraser and Columbia Rivers similarly return to the estuary in summer following Delta overwintering or upriver spawning (Parsley et al. 2008;Robichaud et al. 2017). ...
... White Sturgeon in the Sacramento spawn at similar or higher distances upstream than other systems. White Sturgeon spawn approximately 180-234 rkm in the Columbia River and~100-160 rkm in the Fraser River (McCabe Jr and Tracy 1994;Perrin et al. 2003). Our record of two White Sturgeon traveling above Butte City Bridge is supported by movements of a tagged individual tracked to Ord Ferry Bend, as well as CDFW angler report cards of White Sturgeon captured during our study years between Colusa and Red Bluff and above Red Bluff (Schaffter 1997;Dubois et al. 2012Dubois 2013;Dubois andHarris 2015, 2016;Dubois and Danos 2017). ...
Article
Full-text available
Green Sturgeon (Acipenser medirostris) and White Sturgeon (A. transmontanus) are closely related species inhabiting the San Francisco Estuary (SFE) and Sacramento River. Both spawn in the Sacramento River. White Sturgeon typically remain within SFE throughout their lives while subadult and adult Green Sturgeon make marine migrations. These broad-scale patterns are known. However, the reach-specific timing of spawning migrations is not, and little is known about seasonal movements of juveniles and subadults. We tagged 41 Green and 160 White Sturgeon with acoustic transmitters (2010–2012). Analyses also included 167 previously tagged sturgeon. Over 300 receivers deployed throughout the Sacramento River, SFE, and nearshore Pacific Coast detected movements. Adult Green Sturgeon moved quickly though SFE to their spawning reach, using the mainstem through the Delta. 5% of spawning Green Sturgeon remained on the spawning reach for over 300 days. White Sturgeon spent significantly less time in their spawning reach before exiting (32 ± 48.2 days vs. 197 ± 97.3 days) and instead selected northern Delta sloughs over the mainstem for pre-spawning migrations. Even at earlier life stages, Green Sturgeon had more marine distributions than White Sturgeon. Juveniles and subadults of both species moved between the San Francisco Bay and Delta throughout the year, but only White Sturgeon overwintered in the Delta. Additionally, we refine several life history parameters for sturgeon in California. We provide a comprehensive characterization of Green and White Sturgeon movements within the SFE and Sacramento River across life stages. These analyses will inform reach-specific management of each species.
... White Sturgeon are iteroparous broadcast spawners, This article has been contributed to by US Government employees and their work is in the public domain in the USA spawning in the spring and early summer when water temperatures are between 7-18°C (Kohlhorst, 1976;Paragamian & Wakkinen, 2002;Parsley, Beckman, & McCabe, 1993). White Sturgeon spawn near the river bottom in areas with high hydraulic complexity (Perrin, Rempel, & Rosenau, 2003). Newly fertilized eggs (or embryos) are negatively buoyant and adhere to cobble or boulder substrate where incubation occurs (Parsley et al., 1993). ...
... However, from 1949 to 1993 the average discharge in June at Bonneville Dam decreased from 14,000 m 3 ·s to 6,000 m 3 /s while the maximum water temperature increased by 1.8°C (Quinn & Adams, 1996). White Sturgeon likely used the natural river discharge and thermal regimes as cues to seek out optimal spawning habitats and initiate spawning (Parsley & Beckman, 1994;Perrin et al., 2003). Dam construction and operation have also reduced the quantity and quality of spawning habitats (Chapman & Jones, 2010;Parsley & Beckman, 1994) and disrupted historical migration patterns (North, Beamesderfer, & Rien, 1993). ...
Article
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The goals were to (i) determine if river discharge and water temperature during various early life history stages were predictors of age-0 White Sturgeon, Acipenser transmontanus, recruitment, and (ii) provide an example of how over-dispersed catch data, including data with many zero observations, can be used to better understand the effects of regulated rivers on the productivity of depressed sturgeon populations. An information theoretic approach was used to develop and select negative binomial and zero-inflated negative binomial models that model the relation of age-0 White Sturgeon survey data from three contiguous Columbia River reservoirs to river discharge and water temperature during spawning, egg incubation, larval, and post-larval phases. Age-0 White Sturgeon were collected with small mesh gill nets in The Dalles and John Day reservoirs from 1997 to 2014 and a bottom trawl in Bonneville Reservoir from 1989 to 2006. Results suggest that seasonal river discharge was positively correlated with age-0 recruitment; notably that discharge, 16 June–31 July was positively correlated to age-0 recruitment in all three reservoirs. The best approximating models for two of the three reservoirs also suggest that seasonal water temperature may be a determinant of age-0 recruitment. Our research demonstrates how over-dispersed catch data can be used to better understand the effects of environmental conditions on sturgeon populations caused by the construction and operation of dams.
... Lake sturgeon eggs were found more often in heterogeneous substrates compared with stations sampled with homogeneous substrate classes (LaHaye et al. 1992). Perrin et al. (2003) found that hydraulic complexity and substrate heterogeneity were important factors in determining where white sturgeon spawned in the lower Fraser River, British Columbia, Canada. Spawning areas of Gulf sturgeon A. oxyrinchus desotoi and white sturgeon have also been associated with river topography and complex flow dynamics (Sulak and Clugston 1998;Perrin et al. 2003). ...
... Perrin et al. (2003) found that hydraulic complexity and substrate heterogeneity were important factors in determining where white sturgeon spawned in the lower Fraser River, British Columbia, Canada. Spawning areas of Gulf sturgeon A. oxyrinchus desotoi and white sturgeon have also been associated with river topography and complex flow dynamics (Sulak and Clugston 1998;Perrin et al. 2003). One river characteristic, elevated barchans along the bottom of the river, was observed at both Big Manistee River spawning locations. ...
Article
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Spawning sites of lake sturgeon Acipenser fulvescens were verified using egg collection mats in the Big Manistee River in northwestern lower Michigan. Photographs taken by a fixed-position underwater video camera were used to characterize the substrate at egg mat locations. A total of 3,913 lake sturgeon eggs were captured at two discrete spawning locations in 2003 and 2004. Spawning locations consisted of 34–44% cobble and 0.04–8% sand, and nonspawning locations consisted of 2–43% cobble and 0.16–7% sand. Shannon diversity indices describing substrate heterogeneity at spawning locations were statistically higher than those for nonspawning locations in 2003 (P = 0.002). Four spawning events (one in 2003 and three in 2004) were documented at water temperatures ranging from 11.1°C to 14.8°C and egg incubation periods ranging from 6 to 10 d. Depth at spawning sites was 1.5–3.0 m, average water velocity was 0.34–1.32 m/s, and near-substrate water velocity was 0.08–1.26 m/s. The topography of the Big Manistee River channel appears to have been altered by manipulated river flows, resulting in the development of barchans (ridges or shelves along the river bottom) in the region utilized for spawning. This study is the first to document lake sturgeon spawning success in the Big Manistee River and identify the specific characteristics of spawning bed material used as well as the presence of barchans that may produce eddies or turbulent irregular flows that affect egg dispersal and survival.
... In a similar stream tube, pallid sturgeon Scaphirhynchus albus and shovelnose sturgeon S. platorhynchus drifted mostly downstream at the surface , and white sturgeon A. transmontanus larvae moved downstream at an average height of 4-58 cm from the bottom (Kynard and Parker, 2005). In the Fraser River, British Columbia, sampling with D-frame drift nets captured one white sturgeon larvae at the surface and all others on the bottom; however, mid-water depths were not sampled (Perrin et al., 2003). The results of these studies suggest that the vertical distribution of sturgeon larvae is variable. ...
... Although intended for use in larval lake sturgeon studies, this vertical net design can be used to sample a variety of larval fish in river systems. Other sturgeon species, as well as some members of Cyprinidae, Catostomidae, Salmonidae, and Hiodontidae demonstrate similar larval drift behavior and occupy small, wadeable rivers (Naesje et al., 1986;DÕAmours et al., 2001;Perrin et al., 2003;Johnson and McKenna, 2007). To reduce bias of larval collections, sampling the vertical distribution with nets such as those described here should be an integral part of any drift sampling protocol. ...
Article
Drift nets have been used to document reproductive success of lake sturgeon Acipenser fulvescens. Current net designs and methods for collecting drifting larvae only sample a portion of the water column, which require assumptions of either a benthic or uniform distribution of larvae when estimating abundance or production. The objective of this study was to describe the vertical distribution of larval lake sturgeon in the Peshtigo River, Wisconsin, and to determine if drift was benthic or uniform in distribution. A net was designed to assess the vertical distribution of drifting larvae in 0.2-m increments at depths up to 1.4 m; however, during this sampling, maximum depth did not exceed 0.78 m. The distribution of larval lake sturgeon was neither benthic nor uniform. Only 5% of larvae were captured in the lowest 0.2-m increment, followed by 18% from 0.2 to 0.4 m, 41% from 0.4 to 0.6 m, and 36% from 0.6 m to the surface. Although results will likely differ among years, systems, and the precise location of sampling, our study illustrates the importance of and provides a technique for testing assumptions of the vertical distribution of larval lake sturgeon drift.
... Several populations are listed as imperiled by the United States Fish and Wildlife Service (Birstein et al., 1997). The Kootenai River population is ÔendangeredÕ (Duke et al., 1999) and those of the Fraser, Snake and Columbia rivers are of Ôspecial concernÕ (Perrin et al., 2003;Geist et al., 2005). ...
... Factors such as the decline of white sturgeon populations, ongoing dredging operations, and limited documentation of swimming abilities (Perrin et al., 2003) necessitate the quantification of swimming performance of juvenile white sturgeon. We tested swimming performance of naı¨ve, tested, and trained white sturgeon, and used these data to evaluate probability of entrainment associated with navigation-related dredging. ...
Article
White sturgeon, Acipenser transmontanus (Richardson), are at risk of entrainment from dredging, with young-of-the-year fish at greatest risk. To evaluate this entrainment risk, swimming performance trials were conducted in a laboratory swim tunnel with hatchery-reared juvenile white sturgeon with varying experience levels including: naïve (only tested once), tested (re-tested after being kept in no flow) and trained (re-tested after kept in flow for nearly three weeks). Individuals of various sizes (80–100 mm TL) and all experience levels were strongly rheotactic (> 80%), but endurance was highly variable among fish. Small juveniles [< 82 mm total length (TL)] had lower escape speeds (< 40 cm s−1) than medium (82–92 mm TL) and large (> 93 mm TL) naïve fish (42–45 cm s−1), all of which had lower escape speeds than trained fish (72 cm s−1). Behavior was also highly variable among fish. Overall, benthic station-holding behaviors were least frequent in small fish, intermediate in medium and large fish, and most frequent in trained large fish. Probability of entrainment of juvenile white sturgeon can be reduced by maintaining dredge head flow fields at less than 45 cm s−1 for wild-spawned fish or by rearing hatchery fish to > 93 mm TL and exposing the fish to moderate flow velocities (10–12 cm s−1) prior to their release.
... These results suggest that the transport of fertilized embryos into depositional zones where burial in substrate may occur is unlikely to support survival and hatch of normal free embryos and that these species require clean substrates for spawning and incubation to support successful reproduction and recruitment. Field studies of many sturgeon species have documented spawning in flow conditions that are likely to minimize accumulation of fine sediments over gravel, cobble, and other coarse substrates with interstitial spaces that are thought to protect embryos from predation and scour by mobile sediments (Parsley et al. 1993;Paragamian and Kruse 2001;Perrin et al. 2003;Du et al. 2011;Baril et al. 2017). Whereas results from this study suggest that embryos may experience mortality, physical abnormalities, or delayed hatch if continually covered by fine sediment, the fate of embryos is unclear if sediments cover and uncover developing embryos in repeated episodes as might be expected to occur in large rivers with mobile dunes of fine sediment. ...
Article
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The shovelnose sturgeon ( Scaphirhynchus platorynchus ) and endangered pallid sturgeon ( S. albus ) deposit demersal and adhesive eggs in swift currents, near or over coarse substrate. Hydrographic surveys have demonstrated the dynamic nature of spawning habitats and that coarse substrates may episodically be buried (partially or completely) by fine sediments. To evaluate embryo survival of both species in various substrate conditions, laboratory trials were conducted with substrates of clean glass, gravel, medium-coarse sand (MCS), and fine sand-silt (FSS). Embryos in MCS and FSS were tested three ways: unburied, partially buried, and fully buried (1–2-mm depth). Embryos were exposed to trial conditions for 10 days from the day of fertilization (5 days beyond expected hatching). For both species, mean hatch of normally developed free embryos was highest in unburied treatments where embryos were incubated on substrates and not covered with sediments and ranged from 81.0 to 87.1% for shovelnose sturgeon and 55.2–80.0% for pallid sturgeon. Mean hatch of normal free embryos was lowest where incubating embryos were fully buried by MCS or FSS and ranged from 2.4 to 11.6% for shovelnose sturgeon and 4.8–15.2% for pallid sturgeon. We observed free embryos with physical abnormalities in all treatments; however, the occurrence was most variable in treatments fully and partially buried by MCS. Hatch of both species was also delayed in treatments where embryos were incubated fully and partially buried by MCS. Our results may be useful to estimate the relative suitability of spawning substrates in relevant river reaches.
... However, from 1949 to 1993 the average discharge in June decreased from 14,000 m 3 /s to 6,000 m 3 /s and the maximum water temperature has increased by 1.8˚C [64]. White Sturgeon likely used the natural hydrograph and thermal regime as cues to seek out optimal spawning habitats and initiate spawning [65,68]. ...
Article
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Management actions intended to benefit fish in large rivers can directly or indirectly affect multiple ecosystem components. Without consideration of the effects of management on non-target ecosystem components, unintended consequences may limit management efficacy. Monitoring can help clarify the effects of management actions, including on non-target ecosystem components, but only if data are collected to characterize key ecosystem processes that could affect the outcome. Scientists from across the U.S. convened to develop a conceptual model that would help identify monitoring information needed to better understand how natural and anthropogenic factors affect large river fishes. We applied the conceptual model to case studies in four large U.S. rivers. The application of the conceptual model indicates the model is flexible and relevant to large rivers in different geographic settings and with different management challenges. By visualizing how natural and anthropogenic drivers directly or indirectly affect cascading ecosystem tiers, our model identified critical information gaps and uncertainties that, if resolved, could inform how to best meet management objectives. Despite large differences in the physical and ecological contexts of the river systems, the case studies also demonstrated substantial commonalities in the data needed to better understand how stressors affect fish in these systems. For example, in most systems information on river discharge and water temperature were needed and available. Conversely, information regarding trophic relationships and the habitat requirements of larval fishes were generally lacking. This result suggests that there is a need to better understand a set of common factors across large-river systems. We provide a stepwise procedure to facilitate the application of our conceptual model to other river systems and management goals.
... As an example, adult Gulf Sturgeon Acipenser oxyrinchus desotoi, another riverine sturgeon that prefers swift waters for spawning, are found in waters with velocities near 2.5 m s -1 (Cech and Doroshov 2004). Spawning White Sturgeon require deep areas in rivers with gravel or larger rocks along the bottom and swift water velocities of up to 2.8 m s -1 (Parsley et al. 1993;McCabe and Tracy 1994;Moyle 2002), mean water-column velocities from 0.5 m s -1 to 2.5 m s -1 (Parsley et al. 1993), with near-bed laminar flow velocities averaging 1.7 m s -1 (Perrin et al. 2003). Green Sturgeon need spawning pools with fast waters and eddy flows in depths greater than 3.0 m, and substrates ranging from clean coarse sand to bedrock (Moyle 2002). ...
Article
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This review serves as a guide to improve multi-species fish passage. Human development along waterways in California during the last 160 years has adversely affected fish populations in many watersheds. Conflicts in water usage will only intensify with modern developments and population growth. Since most past fish-passage improvement efforts in California have focused on salmonids, I summarize the published studies and considerations that affect multi-species fish passage. To be effective, conditions in fishways need to meet the specific hydraulic requirements, as well as abilities, behavior, and size consideration for all fish species being considered. Turbulence, water depth, velocity, passage location, and design of a passage facility are essential elements to successful fish passage. Because of a lack of research on most of the native species, species-specific passage criteria are not fully defined, and it may be helpful to use data for physically similar, surrogate species found in similar habitats.
... Embryos are referred to the period of incubation from fertilization through to hatch and YSL refers to the period following hatch to the onset of exogenous feeding. Temperature treatments were developed based on conditions measured at White Sturgeon spawning, incubation and early rearing sites in the upper Columbia River (Golder Associates Ltd. 2009;Terraquatic 2011;AMEC 2014), other White Sturgeon inhabited rivers (Fraser River; Perrin et al. 2003;Kootenai River;Paragamian et al. 2001), and previous studies investigating the effects of temperature on embryotic development (Wang et al. 1985;Parsley et al. 2011). Both ambient (10.0°C) and heated (17.0°C) groundwater were supplied to each treatment with adjustable valves to maintain experimental temperatures throughout the experiment. ...
Article
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Temperature differentially influences developmental trajectories of traits during early life stages that can affect survival and recruitment. Experiments were conducted to quantify temperature-induced developmental responses of White Sturgeon (Acipenser transmontanus) yolk-sac larvae (YSL) reared at temperatures encountered across the species’ range (12.5, 14.0, 15.5, and 17.0 °C). We quantified effects of temperature on timing of transitions between sequential developmental stages from hatch to initiation of exogenous feeding. Rate of development significantly increased at warmer compared to cooler temperatures; no significant difference was observed between 15.5 and 17.0 °C or 12.5 and 14.0 °C. When standardized by relative timing of development (RTi), developmental rate was not significantly different among treatments. Morphological traits (total length; body area; yolk-sac area; head area; gill filament area; mouth area; pectoral fin area) were measured daily, though only data for YSL reared at 12.5 and 17.0 °C was used to quantify phenotypic variation. Morphological traits (excluding yolk-sac area) were generally larger 48+ hours post hatch for YSL reared at 17. 0 °C compared to 12.5 °C. In contrast, these same traits, with the exception of gill filament area, were larger in 12.5 °C reared YSL when considered as a function of developmental stage. These opposing results suggest trade-offs associated with allocating resources to a particular trait depended on rearing temperature. Our results provide the ability to estimate timing of critical early life stages (i.e., hatch, emergence) as a function of temperature which is an important management tool to understand how early life development contributes to recruitment processes and adaptability in thermally altered systems.
... Reproducing populations are found in the Sacramento, San Joaquin, Columbia, and Fraser river basins (Hildebrand et al., 2016). White Sturgeon spawn in water flowing about 1 m/s or faster over gravel-to-boulder sized substrates in water depths greater than about 2e3 m (Parsley et al., 1993;Perrin et al., 2003;Schaffter, 1997). Historical overharvest and vast habitat changes caused by construction of dams and reservoirs and resultant river regulation have affected white sturgeon populations throughout their range, including the Nechako (McAdam et al., 2005), Snake (Bevelhimer, 2002), and San Joaquin (Jackson et al., 2016) rivers. ...
Article
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A study was conducted to identify habitat characteristics associated with age 0+ White Sturgeon (Acipenser transmontanus Richardson, 1863) recruitment in three reaches of the Columbia River Basin: Skamania reach (consistent recruitment), John Day reach (intermittent/inconsistent recruitment), and Kootenai reach (no recruitment). Our modeling approach involved numerous steps. First, we collected information about substrate, embeddedness, and hydrodynamics in each reach. Second, we developed a set of spatially explicit predictor variables. Third, we built two habitat (probability) models with Skamania reach training data where White Sturgeon recruitment was consistent. Fourth, we created spawning maps of each reach by populating the habitat models with in-reach physical metrics (substrate, embeddedness, and hydrodynamics). Fifth, we examined model accuracy by overlaying spawning locations in Skamania and Kootenai reaches with habitat predictions obtained from probability models. Sixth, we simulated how predicted habitat changed in each reach after manipulating physical conditions to more closely match Skamania reach. Model verification confirmed White Sturgeon generally spawned in locations with higher model probabilities in Skamania and Kootenai reaches, indicating the utility of extrapolating the models. Model simulations revealed significant gains in White Sturgeon habitat in all reaches when spring flow increased, gravel/cobble composition increased, or embeddedness decreased. The habitat models appear well suited to assist managers when identifying reach-specific factors limiting White Sturgeon recruitment in the Columbia River Basin or throughout its range.
... Our methods did not allow us to determine what the fish were doing in these summering areas, but it was presumably for feeding opportunities. Neither of these areas are known to be spawning locations for White Sturgeon (Perrin et al. 2003), and few of our tagged fish were likely spawners given their size. Whereas, the timing and destinations of the annual migratory movements observed in this study are consistent with the availability of Eulachon Thaleichthys pacificus and Pacific salmon Oncorhynchus spp. in the lower Fraser River, both of which are known to be important food sources (Semakula and Larkin 1968;Echols and FRAP 1995;McAdam 1995). ...
Article
Details of the spatial ecology of White Sturgeon Acipenser transmontanus in the lower Fraser River, British Columbia, are needed for habitat conservation, assessments of impacts from spatially delimited threats, and refinement of abundance estimation methods. The abundance of threatened lower Fraser River White Sturgeon is assessed annually using a Bayesian, closed-population, mark–recapture model. If individuals make prolonged departures from the lower Fraser River, either into marine waters or a tributary, the validity of the model’s assumed closed population is questionable. There is also concern that fish might move far enough to be exposed to harvest in Puget Sound, Washington. From 2008 to 2012, White Sturgeon of various sizes were acoustically tagged in the Pitt River (n = 58) and in the lower reaches of the Fraser River (near Douglas Island, n = 52) to determine the timing, rate, and spatial extent of movements. Movements were monitored using acoustic receivers at 17 locations in the lowermost 92 km of the main-stem Fraser River, three in the first 21 km of the Pitt River (a tributary to the lower Fraser River), and nine in the coastal waters of British Columbia and Washington State. Travel speeds showed a strong skew toward slower movements (74% were <1 km/h) and did not differ significantly between upstream and downstream directions. On average, 33.2% of the sample was mobile (displacing ~13.4 km/month) and 66.8% was sedentary (displacing ~1.87 km/month). In general, White Sturgeon were significantly more sedentary during winter months and more mobile during spring and fall. Annual or seasonal migratory movements and patterns were observed for 73% of fish tracked. Repeated use of specific locations within the lower Pitt River during midwinter suggested White Sturgeon have a high fidelity for specific overwintering sites. Several of the tagged fish showed annual movements to the lowest reaches of the Fraser River for 1–3 months between May and September, although there was no direct evidence that they left the Fraser River and entered the Strait of Georgia. By contrast, there was strong evidence for extended and repeated movement into the lower Pitt River. Given that the lower Pitt River is outside the mark–recapture assessment area, our results suggest either that the area’s boundaries need expansion, or alternative models should be considered for abundance estimations of lower Fraser River White Sturgeon. Received September 7, 2016; accepted February 3, 2017
... Generally, green sturgeon spawn in areas where turbidity is less than 10 NTU (Poytress et al. , 2011. Conversely, white sturgeon spawn in areas that are generally turbid in nature ( = 42 NTU; Perrin et al. 2003). Average turbidity values in the study reach were 22 NTU. ...
Technical Report
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White sturgeon (Acipenser transmontanus) in the Sacramento-San Joaquin river system were previously known to spawn only in the Sacramento River within a 86 km reach between Knight’s Landing (RK 145) and Colusa (RK 231). Several researchers have suggested that spawning may occur occasionally in the Feather and San Joaquin rivers. Our work provides the first documentation of spawning in the San Joaquin River, California. Artificial substrate samplers (i.e., egg mats) were deployed within a 29 km reach of the San Joaquin River from Sturgeon Bend (RK 119) to upstream of Laird Park (RK 148) from 18 April 2011 to 16 May 2011. During the sample period, 23 white sturgeon eggs were collected downstream of Laird Park at RK 142, 19 of which were viable and between developmental stages 9 and 27. Based upon capture location, date of capture, water temperature, stage of development, and the assumption that a female takes 12–20 hours to release all of her eggs, the eggs likely represent a single spawning event that began on 24 April 2011 at approximately 1300 hours. The results of this survey confirm that white sturgeon do spawn in the San Joaquin River and may be an important source of production for the white sturgeon population in the Sacramento-San Joaquin river system.
... Generally, green sturgeon spawn in areas where turbidity is less than 10 NTU (Poytress et al. , 2011. Conversely, white sturgeon spawn in areas that are generally turbid in nature ( = 42 NTU; Perrin et al. 2003). Because of elevated turbidity levels in the San Joaquin River, we hypothesize that green sturgeon on a spawning run within the San Joaquin River system may be seeking less turbid water upstream of the sampled area in the mainstem or within one of the tributaries where turbidity is lower. ...
... Land-locked populations occur in the Kootenai and upper Columbia Rivers. A 3 m (9 ft) female White Sturgeon can contain close to 5 million eggs, making this species an important resource in the caviar market (Perrin et al., 2003). ...
... White sturgeon Acipenser transmontanus Richardson 1836 are endemic to the Pacific coast of North America, where they are distributed from southern Alaska to Mexico, with the most abundant populations found in the Sacramento, Columbia and Fraser River systems (Scott & Crossman, 1973;Perrin et al., 2003). They are the largest freshwater fish in North America and are a popular target for both commercial and recreational anglers because of their large size and valuable meat and roe. ...
Article
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Effects of two fin-ray sampling methods on swimming performance, growth and survival were evaluated for hatchery-reared sub-adult white sturgeon Acipenser transmontanus. Fish were subjected to either a notch removal treatment in which a small section was removed from an anterior marginal pectoral-fin ray, or a full removal treatment in which an entire marginal pectoral-fin ray was removed. Control fish did not have fin rays removed, but they were subjected to a sham operation. A modified 3230 l Brett-type swim tunnel was used to evaluate 10 min critical station-holding speeds (SCSH ) of A. transmontanus, immediately after the fin ray biopsies were obtained with each method. Survival and growth were evaluated over a 6 month period for a separate group of fish subjected to the same biopsy methods. Mean ± s.e. 10 min SCSH were 108·0 ± 2·3, 110·0 ± 2·6 and 115·0 ± 3·5 cm s(-1) for the notch removal group, full removal group and control group, respectively, and were not significantly different among treatments. Behavioural characteristics including tail-beat frequency and time spent hunkering were also not significantly different among treatment groups swimming at the same speeds. There were no mortalities and relative growth was similar among treatment groups. Average biopsy time for the notch removal method was lower and the wounds appeared to heal more quickly compared with the full removal method.
... White sturgeon Acipenser transmontanus Richardson 1836 are endemic to the Pacific coast of North America, where they are distributed from southern Alaska to Mexico, with the most abundant populations found in the Sacramento, Columbia and Fraser River systems (Scott & Crossman, 1973;Perrin et al., 2003). They are the largest freshwater fish in North America and are a popular target for both commercial and recreational anglers because of their large size and valuable meat and roe. ...
Conference Paper
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Several populations of white sturgeon (Acipenser transmontanus) on the Pacific Coast of North America currently support recreational fisheries; however, quantifiable age and growth data are needed to ensure effective management. Methods for non-lethal sampling of pectoral fin spines have been used to obtain similar data from other sturgeon species; however, effects on the swimming performance of white sturgeon have not been assessed. The objective of this study was to assess the affects of two different fin-spine sampling methods (T1-notch removal; T2-full removal) on the swimming performance and behavior of captive white sturgeon (n=15 per treatment). Using a modified Brett-type swim chamber, we determined critical station-holding speed (CSHS) and swimming behaviors to quantify significant differences in the swimming performance of sturgeon subjected to each fin spine sampling method. Our results showed that mean CSHS (± SE) of controls, T1, T2 were 115 cm/s (± 3.8), 108 cm/s (± 2.3), and 110 cm/s (± 2.6) respectively, indicating that fin-spine sampling had no significant effect on CSHS. Results from this study suggest that non-lethal sampling of pectoral fin spines in white sturgeon is minimally invasive. Additional experiments are being conducted to evaluate long-term effects of fin spine sampling on the survival and growth of white sturgeon.
... The first suitable site moving upstream occurred near the confluence of the Black River and Ogeechee River, near rkm 83, which is where we assumed that spawning would occur. Tributary confluences tend to collect coarse substrate deposits and are known to be used for spawning by sturgeon species including Shortnose Sturgeon (Collins et al. 2000a) and White Sturgeon (Perrin et al. 2003). Field research is needed to confirm both spawning locations and monitor movements of early life stages. ...
Article
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Southern populations of the federally endangered Shortnose Sturgeon Acipenser brevirostrum are considered to be at greater risk of extirpation than northern populations. Our study focused on the Ogeechee River, Georgia, a small, undeveloped, coastal river that supports a population with fewer than 300 Shortnose Sturgeon. We designed a population viability analysis (PVA) model to represent and quantify the demographic influences of three factors (poor water quality, intrusion of saline water via rice canals, and incidental harvest) on the viability of this population. As an isolated population, only 75% of simulated populations persisted beyond a 20-year time horizon with all factors simulated. However, immigration from the Altamaha River may help to support the population. We quantified population persistence with and without simulating each factor and found that (1) incidental harvest had no effect on simulated persistence, (2) poor water quality decreased simulated persistence by 29%, primarily due to low oxygen conditions in summer, and (3) roughly one-third of this effect was attributed to rice canals (premature exposure of juveniles to high salinities). Simulated recruitment to age 1 was limited by a habitat squeeze between density-dependent starvation upstream near the spawning grounds and premature exposure to salinity downstream. These results highlight a need for research on availability of summer refuge and freshwater rearing habitat. As these results derived from a PVA model, which required many assumptions, they should be considered preliminary. Further field research is needed to confirm those results where it is possible to test intermediate predictions. We conclude by suggesting that efforts to maintain or increase the number of viable populations of Shortnose Sturgeon in southern U.S. rivers will probably require an understanding of (1) source-sink dynamics between populations in rivers with access to adequate freshwater rearing habitat and those without, and (2) the effects of climate change.Received January 19, 2012; accepted December 25, 2012
... Sampling location within a site remained consistent across years ( Figure 1). The period of sampling coincided with typical thermal regimes (12-18 C) documented during White Sturgeon spawning activity (Parsley and Beckman 1994;Hildebrand et al. 1999;Paragamian et al. 2001;Perrin et al. 2003). Due to warmer temperature influences of the Pend D'Oreille River, sampling at Waneta was initiated on June 13 in 2011 and June 11 in 2012. ...
Article
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Accurate estimates of the number of spawning adults contributing to offspring (Ns), effective breeding number (Nb), and estimates of individual adult contributions to recruitment are required for recovery planning for endangered White Sturgeon Acipenser transmontanus populations, many of which are suffering from prolonged periods of recruitment failure. We show that genetic techniques can be used to characterize important features of White Sturgeon reproductive ecology in large rivers where census data are extremely difficult to obtain. We used microsatellite loci (n=12) and likelihood-based pedigree analysis to estimate Ns, Nb, number of kin groups (Nk) and individual reproductive success of White Sturgeon contributing to viable eggs and larvae collected in the Upper Columbia River in each of two years. Estimates of mean annual Ns, Nb, and Nk (mean ± SD) were 121.5 ± 34.7, 86.5 ± 10.6, and 73.5 ± 17.3, respectively. Large variations in estimates of Ns, Nb, and Nk were observed between spawning areas (n=3), with one spawning site representing 61% of total adult spawning population. Variation in adult reproductive success was observed within and among sites. Individual spawning duration (1.9 ± 1.1 days) and number of mates per adult (2.9 ± 2.5) likewise varied spatially and temporally. Based on age of collected eggs and larvae, number of spawning days ranged from 5 to 19 between years and among sites. Genetically derived estimates of Ns were lower but generally concordant with empirical estimates of available spawners (Nc) based on sex ratios and maturation staging of adults captured independently (Ns/Nc ratio = 0.683). Results increase our understanding of White Sturgeon reproductive ecology and recruitment, and allow projections of cohort levels of genetic diversity. Similar data can be applied to recovery planning and aquaculture programs for this and other species of conservation concern.
... However, currently, there is no direct evidence that silt content can affect the migration of the fish. After the study on white sturgeon spawning habitat in an unregulated river, Perrin et al. (2003) hypothesize that reduced light attenuation due to turbidity may substantially influence habitat suitability for spawning within the range of available water Table 4 Stepwise regression analysis and number of A. sinensis juveniles (J) depths and velocities. A. sinensis also exhibit a degree of active selectivity with respect to sediment concentration during natural reproduction (Yangtze Aquatic Resources Survey Group 1988;Wei 2003;Yang et al. 2007). The present study indicates that the AASC in the Yangtze River also has an impact on the breeding migration of A. sinensis. ...
Article
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Since 2003, the flow characteristics of the Yangtze River, currently the only river where the protected Chinese sturgeon, Acipenser sinensis, spawns and where the young grows to the 6 to 8 month juvenile stage, has been regulated by the operation of the Three Gorges Project. The number of seaward migrating juveniles captured (NSMJC) in the Yangtze estuary from 2002 to 2010 was significantly positively related (Pearson correlation, P (two tailed) <0.01; Lg (NSMJC) = 0.870 + 3.930 × AASC, R = 0.940, P = 0.000) to the annual sediment load and annual average sediment concentration (AASC) of the previous year, when adults entered the river and migrated upstream, used refuge areas, and spawned, and when early life stages were reared. This suggests that silt content may have a major effect on adult spawning success and rearing of early life stages. Based on the correlation between numbers of juveniles captured and numbers of adults in the spawning areas in the previous year (Pearson correlation, R = 0.965, P (two tailed) = 0.008), we speculated that the sediment characteristics affected the migration and gonad development of mature individuals and, indirectly, the number of juveniles reaching the Yangtze estuary during the following year. Decreased silt levels in the Yangtze River following installation of the Three Gorges Project may be having a deleterious effect on Chinese sturgeon reproduction and needs further research.
... The first suitable site moving upstream occurred near the confluence of the Black River and Ogeechee River, near rkm 83, which is where we assumed that spawning would occur. Tributary confluences tend to collect coarse substrate deposits and are known to be used for spawning by sturgeon species including Shortnose Sturgeon (Collins et al. 2000a) and White Sturgeon (Perrin et al. 2003). Field research is needed to confirm both spawning locations and monitor movements of early life stages. ...
Article
Full-text available
This study used population viability analysis (PVA) to partition the influences of potential threats to the endangered shortnose sturgeon (Acipenser brevirostrum). A workshop brought together experts to help identify potential threats including groundwater withdrawal, poor water quality, saltwater intrusion, mercury effects, harvest as by-catch, and sedimentation of spawning habitat. During the course of the project, we eliminated some threats and added new ones. Groundwater withdrawal was dismissed after a study failed to identify connection with groundwater and the majority of pumping is from a confined aquifer. We also eliminated activities on Fort Stewart as influences on spawning habitat because any successful spawning must occur upstream of Fort Stewart. We added climate change to the list of threats based on our assessment of temperature effects and expectations of sea-level rise. Our study highlighted the role of populations in nearby rivers in providing metapopulation support, raising the concern that the population in the Ogeechee River acts as a demographic sink. As part of this study, we carried out a field sampling study to analyze effects of training activities on headwater streams. We developed a new methodology for sampling design as part of this effort and used a mixed-modeling approach to identify relationships between land cover-land use, including those associated with military training activity and water quality. We found that tank training was associated with higher suspended sediment and equipment training was associated with higher organic carbon and water quality. We detected effects of training on suspended sediment and organic carbon. We also carried out a field sampling effort in the Canoochee and Ogeechee Rivers. In the Ogeechee River, we found that dissolved oxygen in 40% of measurements during summer were below 4 mg L-1. To evaluate mercury as a potential threat, we developed a mercury uptake model and analyzed mercury levels in amphipod prey and sturgeon eggs. These did not exceed EPA guidelines. Finally, we developed a PVA model that including linkages between shortnose sturgeon growth, reproduction, and survival and each remaining threat; All three had significant influences. Preliminary simulations suggest that elevated temperatures under future climate will extirpate this population and add support to the hypothesis that this species requires access to spawning habitat far upstream to persist.
... They are highly fecund nonannual spawn-ers, which typically spawn after the springsummer freshet peak. Spawning sites are most often found in turbulent or turbid river sections areas upstream of floodplains (Parsley and Beckman 1993;Perrin et al. 2003;Coutant 2004); however, many floodplains are now unavailable or severely diminished. Given that spawning and fertilized eggs are regularly observed in populations exhibiting recruitment failure, this problem is apparently not due to lack of egg production. ...
Article
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Reconstructed recruitment was compared with the relatively limited set of anthropogenic alterations to the Nechako watercourse to identify and investigate potential causes of recruitment failure of Nechako River white sturgeon Acipenser transmontanus. Back-calculation of historic recruitment shows that recruitment was present but variable from 1946 until 1964. Subsequent to 1964 there was a rapid decline, principally in 1967, and recruitment failure has continued since that time. Flow regulation, which began in 1952 with the completion of Kenney Dam, preceded recruitment failure by 15 years and therefore flow regulation does not supply a simple unicausal explanation for recruitment failure.We propose that sediment input from an upstream channel avulsion in 1961, in combination with elevated flows in 1964 and 1967, led to alterations to riverbed substrates in critical white sturgeon habitat. Using air photos and specific gauge analysis, we identified a “sediment wave” in the upper Nechako River. The timing and location of avulsion sediments indicates that recruitment failure is most likely due to alteration of main channel substrates rather than the loss of off-channel habitat. Findings are discussed with reference to general hypotheses for recruitment failure in other white sturgeon populations.
... Elements of the basic biology have been chiefly described for sturgeon from the Columbia River (e.g., Galbreath 1985). Remarkably little is known of the biology of sturgeon within the Fraser River, British Columbia, the second largest river on the West Coast; even the location of spawning sites has only recently been reported (Perrin et al. 2003). ...
Article
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Sturgeon movements are poorly known. We report here telemetry data on the marine and freshwater movements of a 188-cm (fork length; probably 30–60 years old) white sturgeon Acipenser transmontanus over a 19-month period. Initially tagged in the Klamath River, California, in May 2002, it remained there until emigrating to the ocean in November 2002. It was next detected more than 1,000 km away in the Fraser River, British Columbia, where it made extended in-river movements in September and October 2003. Given the long periods of time spent in at least two very different river systems (one clear and one highly turbid), the home river is uncertain. Large-scale movements of sturgeon outside the home river have serious implications for population assessments and development of successful management plans. Our results highlight the potential value of permanent large-scale telemetry systems.
... Spawning pads have mainly been used to study spawning habitat selection for sturgeons Acipenser spp. (Marchant and Shutters 1996; Sulak and Cluston 1998; Perrin et al. 2003; Duncan et al. 2004 ). Like sturgeon eggs, hickory shad eggs are initially adhesive and likely to adhere to spawning pads soon after spawning in close proximity to the location of the spawning fish. ...
Article
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We examined the spawning habitat selectivity of hickory shad Alosa mediocris, an anadromous species on the Atlantic coast of North America. Using plankton tows and artificial substrates (spawning pads), we collected hickory shad eggs in the Roanoke River, North Carolina, to identify spawning timing, temperature, and microhabitat use. Hickory shad eggs were collected by both sampling gears in March and April. The results from this and three other studies in North Carolina indicate that spawning peaks at water temperatures between 12.0°C and 14.9°C and that approximately 90% occurs between 11.0°C and 18.9°C. Hickory shad eggs were collected in run and riffle habitats. Water velocity and substrate were significantly different at spawning pads with eggs than at those without eggs, suggesting that these are important microhabitat factors for spawning. Hickory shad eggs were usually collected in velocities of at least 0.1 m/s and on all substrates except those dominated by silt. Eggs were most abundant on gravel, cobble, and boulder substrates. Hickory shad spawned further upstream in years when water discharge rates at Roanoke Rapids were approximately average during March and April (2005 and 2007), as compared with a severe drought year (2006), suggesting that water flows may affect not only spawning site selection but also the quantity and quality of spawning habitat available at a macrohabitat scale. Using our field data and a Bayesian approach to resource selection analysis, we developed a preliminary habitat suitability model for hickory shad. This Bayesian approach provides an objective framework for updating the model as future studies of hickory shad spawning habitat are conducted.Received July 16, 2010; accepted February 21, 2011
... Studies of white sturgeon spawning habitat in other river basins in the western United States where spawning and rearing are successful, such as the Sacramento, the Columbia, and the Fraser rivers, generally describe the location of spawning sites as occurring in river reaches with relatively high velocity and a substrate that is composed of gravel and larger-sized material ͑Paragamian et al. Perrin et al. 2000Perrin et al. , 2003Parsley et al. 1993;Parsley and Beckman 1994;Coutant 2004;Golder Associates 2005͒. However, there are some site-specific differences from these idealized habitat values. ...
Article
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Kootenai River white sturgeon spawn in an 18-km reach of the Kootenai River, Id. Since completion of Libby Dam upstream from the spawning reach in 1972, 1974 is the only year with documented significant recruitment of juvenile fish. Where successful in other rivers, white sturgeon spawn over clean coarse material of gravel size or larger. The channel substrate in the current 2008 18-km spawning reach is composed primarily of sand and some buried gravel; within a few kilometers upstream there is an extended reach of clean gravel, cobble, and bedrock. We used a quasi-three-dimensional flow and sediment-transport model along with the locations of collected sturgeon eggs as a proxy for spawning location from 1994 to 2002 to gain insight into spawning-habitat selection in a reach which is currently unsuitable due to the lack of coarse substrate. Spatial correlations between spawning locations and simulated velocity and depth indicate fish select regions of higher velocity and greater depth within any river cross section to spawn. These regions of high velocity and depth occur in the same locations regardless of the discharge magnitude as modeled over a range of pre-and postdam flow conditions. A flow and sediment-transport simulation shows high discharge, and relatively long-duration flow associated with predam flow events is sufficient to scour the fine sediment overburden, periodically exposing existing lenses of gravel and cobble as lag deposits in the current spawning reach. This is corroborated by video observations of bed surface material following a significant flood event in 2006, which show gravel and cobble present in many locations in the current spawning reach. Thus, both modeling and observations suggest that the relative rarity of extremely high flows in the current regulated flow regime is at least partly responsible for the lack of successful spawning; in the predam flow regime, frequent high flows removed the fine sediment overburden, unveiling coarse material and providing suitable substrate in the current spawning reach.
... cies in Australian rivers. The larvae of most riverine fish species require shallow, slow-water habitats where productivity of small prey is higher, riparian vegetation provides structure, and predators are excluded (Bowen et al. 2003). It remains unclear to what extent incubation habitat contributes to recruitment in white sturgeon (Coutant 2004). Perrin et al. (2003) proposed that productive areas differ in regulated and unregulated rivers and in confined and unconfined channels. They recovered eggs ...
Article
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This paper describes a simulation study of reconnection options for white sturgeon Acipenser transmontanus subpopulations in adjacent river segments above and below CJ Strike Dam on the Snake River, Idaho, USA. In contrast to the downstream river segment, the upstream river segment is long and has areas that are suitable for spawning during normal and wet hydrologic conditions. We evaluated demographic and genetic consequences of upstream and downstream passage using different model assumptions about trashrack spacing and density-dependent effects on the spawning interval. Our genetic results predict that, although reconnection would introduce new alleles to the upstream subpopulation, it would also preserve alleles from the down-stream subpopulation by propagating them in the larger subpopulation above the dam. Our demographic results predict that halving the space between trashracks would have large and unequivocal benefits, whereas the predicted effects of reconnection were smaller and more sensitive to model assumptions. Simulated upstream passage tended to benefit both subpopulations only in the absence of density-dependent limitation. In the presence of density dependence, the combination of halved trashrack spacing and upstream and downstream passage produced the best results. Narrower trashracks kept spawning adults in the upstream segment with spawning habitat, while allowing their progeny to migrate downstream. Screening appears to be the best option for such a species in this configuration of a long river segment acting as a demographic source above a short one acting as a demographic sink.
... They are benthic oriented fishes that exhibit a freshwater amphidromous form of diadromy with some immature and adult fish occasionally entering estuaries and the Pacific Ocean (DeVore et al., 1995;Welch et al., 2006). They use a broad range of riverine habitats throughout their life, with spawning occurring in swift turbulent areas (Parsley et al., 1993;McCabe and Tracy, 1994;Schaffter, 1997;Paragamian et al., 2002;Perrin et al., 2003) and foraging or rearing occurring in lower velocity areas (Parsley et al., 1993). Juvenile and adult seasonal and daily activity patterns are complex (Haynes and Gray, 1981;Paragamian and Duehr, 2005;Parsley et al., 2008) and reveal that white sturgeon use a broad range of water depths. ...
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Concerns over the potential effects of in-water placement of dredged materials prompted us to develop a GIS-based model that characterizes in a spatially explicit manner white sturgeon Acipenser transmontanus rearing habitat in the lower Columbia River, USA. The spatial model was developed using water depth, riverbed slope and roughness, fish positions collected in 2002, and Mahalanobis distance (D2). We created a habitat suitability map by identifying a Mahalanobis distance under which >50% of white sturgeon locations occurred in 2002 (i.e., high-probability habitat). White sturgeon preferred relatively moderate to high water depths, and low to moderate riverbed slope and roughness values. The eigenvectors indicated that riverbed slope and roughness were slightly more important than water depth, but all three variables were important. We estimated the impacts that fill might have on sturgeon habitat by simulating the addition of fill to the thalweg, in 3-m increments, and recomputing Mahalanobis distances. Channel filling simulations revealed that up to 9 m of fill would have little impact on high-probability habitat, but 12 and 15 m of fill resulted in habitat declines of ∼12% and ∼45%, respectively. This is the first spatially explicit predictive model of white sturgeon rearing habitat in the lower Columbia River, and the first to quantitatively predict the impacts of dredging operations on sturgeon habitat. Future research should consider whether water velocity improves the accuracy and specificity of the model, and to assess its applicability to other areas in the Columbia River.
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The goal for using genetic information derived from embryo samples is to gain insight into the reproductive biology of adult white sturgeon, Acipenser transmontanus Richardson. The relationship between egg development stages on the extraction of quality DNA was determined, and subsequent genotype data were used to infer contributing spawner numbers. White sturgeon DNA was present in extractions from all stages; however, pre-gastrulation stage embryos generally failed to amplify sufficient genetic loci for analysis. Using experimentally created families, multivariate ANOVA and maximum-likelihood sibship methods estimated the presence of 10 contributing parents from 11 actual adult spawners. It was observed that unidentified half-sibling relationships (offspring sharing one parent) caused error for inferring parent numbers. Genetic methods estimated 13–40 parents potentially contributed to a collection of wild-caught embryos, with variable numbers of parents inferred from separate spawning events (varying from 8 to 24). Egg source material provides a means to enhance the accuracy of annual spawning population size estimates, which is important for informing habitat restoration, harvest and water management decisions and recovery planning.
Article
Ultrasonic and radio telemetry has proven to be a valuable tool in movement and behavior studies of white sturgeon (Acipenser transmontanus) in the Pacific northwest. Our objective was to determine if external attachment of paired transmitters (ultrasonic and radio) allowed adequate retention time to satisfy our objective of monitoring adult white sturgeon through a minimum of 120 d during the pre-spawn and spawning season. From 1993 through 2003 we attached ultrasonic transmitters to 34 adult white sturgeon and both ultrasonic and radio transmitters to 108 adult white sturgeon. The mean transmitter availability was 830 d for single and 701 d for paired transmitters. Mean attachment duration was 309 d for single transmitter and 490 d for paired transmitters. Five individuals (14.7%) shed ultrasonic and 33 (30.6%) shed paired ultrasonic and radio transmitters before the end of the life expectancy of the ultrasonic transmitter batteries. We were unable to detect a significant difference in tag retention time between the paired and unpaired tags. Deployment of both ultrasonic and radio transmitter on a white sturgeon did not appear to compromise our studies with most transmitters staying attached for at least 120 d. However, once a tag had been on 0-600 days, single tag deployments performed better. For short term investigations our study suggests managers and researcher of white sturgeon populations can benefit from attaching both transmitters but long term studies should be restricted to deployment of a single transmitter. © 2005 by the Northwest Scientific Association. All rights reserved.
Article
White sturgeon (Acipenser transmontanus) in the lower Columbia River system were previously known to spawn in only one area; within the 12 km of mainstem Columbia River downstream of Bonneville Dam. Our work provides the first documentation of white sturgeon spawning in the Willamette River, Oregon, a major tributary of the lower Columbia River. We used artificial substrates to sample for white sturgeon eggs downstream of Willamette Falls from 18 May to 20 May 2009 and collected a total of 22 fertilized eggs. Embryonic developmental stages ranged from pigmentation change (Stage 2) to early epithelial (Stage 8), corresponding to fertilization times of approximately 5–17 hours prior to collection. We estimated that spawning occurred between 2100 hours on 19 May and 0900 hours on 20 May 2009, and that a minimum of three independent spawning events took place during that time. Results suggest that the area immediately downstream of Willamette Falls may be important white sturgeon spawning habitat, and that the lower Willamette River is likely an additional source of production for the white sturgeon population in the lower Columbia River system.
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Damming of large rivers in the U.S. Pacific Northwest and Canada has divided the historical population of white sturgeon Acipenser transmontanus into more than 36 fragmented populations, few of which are thriving. We now face the challenge of managing these populations to avoid extirpation. Two goals of this study were to identify extinction thresholds related to small size and inadequate habitat for this species. The minimum viable population size (MVP) is the threshold size above which populations support recruitment and grow and below which populations fail to support recruitment and decline. We estimated a single, cross-population MVP using data from multiple populations and quantile regression, which removed the effects of factors other than population size. Only two populations (those in the Bonneville and Dalles reservoirs on the Columbia River), both with significant increasing trends, were larger than our MVP estimate. We detected significant decreasing trends in two populations—those below Bonneville Dam and in the Kootenai River. To discover how site-specific differences in river habitat influence MVP, we used a population viability analysis (PVA) model that incorporated Allee mechanisms. The PVA model identified a river segment length below which extinction was certain regardless of initial population size. Above this threshold, simulated populations in river segments that were longer or that provided more frequent recruitment opportunities were able to persist with smaller initial sizes. Two priorities emerged for white sturgeon: monitoring age structure and understanding the circumstances preventing recruitment to age 1. Our results ultimately guided us toward thresholds in rearing habitat and age structure that promise to develop into more useful conservation tools than MVP for this and similar long-lived species.
Article
White sturgeon Acipenser transmontanus occur in rivers of the western United States and southwestern Canada, but some populations are in decline because of recruitment failure. Many river systems in this area have been altered as a result of development that has caused major environmental changes. Our goal was to examine how three changes—lower turbidity levels, higher light levels, and altered substrates—might affect predation by prickly sculpin Cottus asper on white sturgeon larvae. We experimentally investigated predation at various turbidity levels and found that significantly more white sturgeon yolk sac larvae were eaten at lower turbidity levels. The effects of light level (1–4 and 7–15 lx), the presence or absence of rocks as cover, and prey size (14–17 mm and 20–24 mm total length) on the outcome of predator–prey interactions were also examined. Significantly fewer white sturgeon were eaten during trials that combined the lowest light level, cover, and the smallest larvae. Our results suggest that altered river conditions caused by impoundment and other factors have increased predation on white sturgeon larvae.
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The hydraulics and morphology of secondary channels within the lower Fraser River gravel reach were examined using data collected with an acoustic Doppler profiler during the large 2002 freshet. Data were collected over an area of channel (``subreach''), for a range of subreach morphologies (``upstream,'' ``mid,'' and ``downstream''). As suggested by visual evidence, at-a-station hydraulic geometry of subreach types stratified along gradients of width, depth, and velocity. Fish habitat is more abundant and more persistently available in the wide, deep downstream subreaches, but higher velocities preferred by some species occur in the mid stream and upstream subreaches. Additional high-flow data, used to develop bank-full scaling relations (classical ``downstream'' hydraulic geometry), conformed well to a simple power law up to and including data points from the main channel. However, width and depth exponents deviated from classical results. Investigation suggests that the relations observed in this study approach expected relations for constant slope and channel boundary materials.
Article
White sturgeon (Acipenser transmontanus) has recruitment failure or severe interannual variability in much of its range. Exceptions are Columbia River below Bonneville Dam, Snake River below Hells Canyon Dam, lower Fraser River, and Sacramento River. Since rivers were impounded or flows regulated, once-continuous populations now isolated by natural barriers or dams often have not reproduced successfully, despite successful spawning events. Research has not adequately explained recruitment failures or why certain populations are successful. This paper proposes that submerged riparian habitat during seasonal high water is needed for early development. Where recruitment is successful, channels are complex and floodable riparian vegetation or rocky substrate is abundant. There, spawning occurs in turbulent zones upstream (1–5 km) of seasonally submerged riparian habitat, eggs can disperse into inundated habitat and adhere to newly wetted surfaces for incubation, yolk-sac larvae can move to riparian crevices for prefeeding development, feeding larvae have food-rich flooded habitat for early growth, and larvae can transition to juveniles as water recedes to permanent channels. Such habitat is lacking where recruitment is low and present only in high-flow years where recruitment is sporadic. These observations suggest that management should rehabilitate riparian zones and provide high river flows during spawning to stimulate natural recruitment.
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A passive sampling technique was developed to collect eggs and confirm potential spawning sites for paddlefish Polyodon spathula in sandbed reaches of the lower Yellowstone River, Montana and North Dakota. In 2000, egg collectors modeled after the mats used in sturgeon research proved difficult to retrieve from the riverbed and did not collect eggs. In 2001 and 2002, tubular egg collectors designed to remain suspended off the bottom were successfully retrieved 97% of the time and collected 130 acipenseriform eggs along suspected spawning sites (99% of differentiable eggs were genetically confirmed as paddlefish). In both years, eggs were typically collected in mid-June after peak periods of Yellowstone River discharge and at river temperatures of 15–22°C. During collection periods in 2001 and 2002, 20% and 45% of retrieved tubes, respectively, had at least one egg, and 84% of all eggs were found on tubes retrieved from the channel thalweg. Although eggs were spatially distributed in a clumped manner at sample sites, the mean number of eggs per tube was low (
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Characterization of riverine spawning habitat is important for the management and restoration of anadromous alosines. We examined the relative effectiveness of oblique plankton tows and spawning pads for collecting the eggs of American shad Alosa sapidissima, hickory shad A. mediocris, and “river herring” (a 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 tows, 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.
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Nearly 430,000 larval pallid sturgeon Scaphirhynchus albus (5–13 d posthatch) were released in the Missouri River and allowed to free-drift for 5.7 km and then were sampled at a river bend by boats positioned on the inside-bend, inside-bend channel border, mid-channel, and outside-bend locations of the channel. Boats were rigged with conical nets and rectangle nets designed to sample for drifting pallid sturgeon larvae along the bottom and at the surface of the river to address three objectives: (1) examine the vertical drift behavior of larvae; (2) compare numbers, concentrations, and lengths of larvae between conical and rectangle nets; and (3) examine the lateral distribution of free-drifting larvae. The vertical distribution of larvae was not uniform as nearly all larvae (≥98%) were sampled in nets fished on the bottom, and larval concentrations (expressed as larvae/m) were greater in bottom-fished nets. Large-opening rectangle nets (0.375 m) fished on the bottom sampled greater numbers of larvae than small-opening conical nets (0.196 m) fished on the bottom; however, larval concentrations were similar between the two net designs. Numbers and concentrations of larvae differed among lateral sampling locations and increased from the inside-bend location to the outside-bend location. Lengths of sampled larvae were similar between net designs and vertical locations in the water column, but larvae sampled at the mid-channel location were slightly smaller than larvae sampled at other lateral locations. These results serve as a guide for sampling larval pallid sturgeon in large rivers. Specifically, sampling adjacent to the bottom in the high-velocity thalweg of the channel maximizes the likelihood of collecting larvae and quantifying numbers of drifting larvae of this federally endangered species.
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Our objectives were to determine the general water column habitat use of Kootenai River white sturgeon Acipenser transmontanus during the prespawn and spawning periods and to determine the degree of their benthic existence. Depth-sensitive radio transmitters were attached to five male and four female white sturgeon and were periodically monitored day and night from April through June 2001. A total of 297 radio contacts were made, of which 209 included the depth of the river. One fish was not used for statistical analysis because its behavior was often modified by the presence of our boat. Of the 209 contacts, 75% (156) were made within the bottom one-third of the water column. Mean depth of the fish during the daytime prespawn and daytime spawning period was different (9.7 and 6.5 m, respectively), and the distribution between these two periods was significantly different. Some of the variation was likely due to the deeper habitat of the daytime prespawn staging reach compared with that of the daytime spawning period location (12.6 and 7.7 m, respectively). White sturgeon used a variety of locations throughout the water column, were closer to the river bottom during the spawning period, and were much more mobile during the spawning period than we previously believed. We were also able to chart some white sturgeon as they gradually cruised the contour of the river bottom several meters from the substrate yet paused momentarily. Although depth-sensitive transmitters were well suited to further defining some white sturgeon behavioral characteristics, they lacked the precision to achieve instantaneous locations.
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Habitat suitability index models for American shad Alosa sapidissima were developed by Stier and Crance in 1985. These models, which were based on a combination of published information and expert opinion, are often used to make decisions about hydropower dam operations and fish passage. The purpose of this study was to develop updated habitat suitability index models for spawning American shad in the southeastern United States, building on the many field and laboratory studies completed since 1985. We surveyed biologists who had knowledge about American shad spawning grounds, assembled a panel of experts to discuss important habitat variables, and used raw data from published and unpublished studies to develop new habitat suitability curves. The updated curves are based on resource selection functions, which can model habitat selectivity based on use and availability of particular habitats. Using field data collected in eight rivers from Virginia to Florida (Mattaponi, Pamunkey, Roanoke, Tar, Neuse, Cape Fear, Pee Dee, St. Johns), we obtained new curves for temperature, current velocity, and depth that were generally similar to the original models. Our new suitability function for substrate was also similar to the original pattern, except that sand (optimal in the original model) has a very low estimated suitability. The Bayesian approach that we used to develop habitat suitability curves provides an objective framework for updating the model as new studies are completed and for testing the model's applicability in other parts of the species' range.
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Fifty white sturgeon (Acipenser transmontanus) eleutheroembryos (average size 0.17 g) were placed onto each of four quadrants (0.45 m2 quadrant−1; 200 fish tank−1) of different sized substrates in four circular tanks (approximately 562 L). Each of three quadrants had a different size substrate and the fourth quadrant was left bare. We used one replicate of smaller size substrates (0.5–11.9 mm) and one replicate of larger size substrates (21.7–88 mm). It was found that the white sturgeon eleutheroembryos preferred substrate with an average size (longest diameter) of 12 mm (11.9) in the smaller substrate range and 22 mm (21.7) in the larger substrate range. These data improve our knowledge of white sturgeon early life history, and if confirmed in the wild can be used to protect areas that are crucial for white sturgeon recruitment and survival.
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The primary objective of this study was to identify and characterize juvenile white sturgeon (Acipenser transmontanus) habitat in the Lower Fraser River downstream of Hope, BC, Canada. A secondary objective was to estimate the juvenile white sturgeon population in the Lower Fraser River. A total of 1867 white sturgeon was captured with gill nets at 26 sites in the Lower Fraser River. The greatest numbers of sturgeon were caught in three sloughs; all but three sturgeon were captured in the June to August period. These three sloughs all had water deeper than 5 m and current that was multidirectional. Turbidity ranged greatly from 1.5 NTU (Nephelometric Units) to 67.0 NTU and the substrate of most sites was fine sediments, fine sand, silt and clay. Stomach contents were mysid shrimp (Mysidacea), midge larvae (Chironomidae) and peamouth chub (Mylocheilus caurinus). We identified three of 26 sites with appreciable numbers of juvenile sturgeon, identified water quality parameters of these sites, identified any incidental species that might be prey and also determined that between 1985 and 1993 the juvenile white sturgeon population had declined.
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Known as the four famous carps in China, black carp (Mylopharyngodon piceus), grass carp (Ctenopharyngodon idella), silver carp (Hypophthalmichthys molitrix) and bighead carp (Hypophthalmichthys nobilis) are commercially important fish species with a high production in China. To reveal the relationships between meteorological conditions and the natural spawning behavior of these fishes, we considered six meteorological factors (including wind, rainfall, temperature, air pressure, sunshine hours and humidity) and the weather conditions in 80 spawning events. The results showed that the spawning activities were more likely to be activated in consecutive rainy days or days when weather changed drastically, while the spawning activities showed no tendency for the weather type except consecutive rainy days. Our analyses also showed that the average rainfall in the initial spawning days is higher than that in the spawning time windows (the time from the earliest spawning activity to the latest spawning activity), while other meteorological elements remained at more or less the same values in both time periods; spawning activity tended to happen in days when the average air pressure was going down or the average temperature going up, while the other meteorological elements showed no consistent tendency. KeywordsChina-Carp-Natural reproduction-Meteorological condition-Yangtze River
Article
Regulation of river flow and the amount of winter rainfall are the major factors affecting the water temperature of the spawning grounds, for green sturgeon in the Klamath River. During the primary spawning period of green sturgeon, mid-April to June, the water temperature may vary from 8 to 21C. To estimate the potential implications of this modified thermal regime, we examined the survival and development in three progeny groups of green sturgeon embryos from zygote to hatch, at constant incubation temperatures (11–26C). Temperatures 23–26C affected cleavage and gastrulation and all died before hatch. Temperatures 17.5–22C were suboptimal as an increasing number of embryos developed abnormally and hatching success decreased at 20.5–22C, although the tolerance to these temperatures varied between progenies. The lower temperature limit was not evident from this study, although hatching rate decreased at 11C and hatched embryos were shorter, compared to 14C. The mean total length of hatched embryos decreased with increasing temperature, although their wet and dry weight remained relatively constant. We concluded that temperatures 17–18C may be the upper limit of the thermal optima for green sturgeon embryos, and that the river thermal regime during dry years may affect green sturgeon reproduction.
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A review of endangered and threatened chondrostean (sturgeon and paddlefish) species is given. It is shown that at least three species from the territory of the former Soviet Union are the most endangered. Among them is the large Amu-Dar shovelnose Pseudoscaphirhynchus kaufmanni, which seems to be the last survivor of the most primitive group among sturgeons, still living in the region where it originated. These facts call for quick conservation efforts. Because of the present economic crisis in Russia, there is no hope that such effort can be made by Russian scientists alone. Saving sturgeons should be a goal of the international community.Resumen: Se presenta una revisión de especies condrósteas (esturion y pez espátula) en peligro y amenazadas. Se muestra que por lo menos tres especies del territorio de la ex Unión Soviética son las más comprometidas. Entre ellas se encuentra el gran Amu-Dar Pseudoscaphirhyncus kaufmanni, que parece ser el último sobreviviente del grupo más primitivo de esturiones, que aun vive en la región donde fue originado. Estos hechos claman un pronto esfuerzo conservacionista. Debido a la crisis económica actual en Rusia, no hay esperanzas de que tales esfuerzos puedan ser realizados solo par cientificos rusos. La salvación de los esturiones debería ser un objetivo de la comunidad internacional.
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Serotonergic dysfunction is implicated in Alzheimer's disease (AD) on the basis of studies of serotonin and its metabolite in postmortem specimens and CSF. There were also reports on association of a tryptophan hydroxylase (TPH) intron 7 variant and CSF 5-hydroxyindoleacetic acid concentrations. These suggested TPH might be a candidate to study for possible involvement in AD. Using a case-control association approach, we studied the TPH polymorphism in 150 subjects with AD and 100 controls. There were no significant differences in genotype or allele frequencies between controls and AD patients. The negative findings suggested that this TPH polymorphism has no major effect on the development of AD. However, the genetic variation of the TPH gene related to the symptomatology of AD deserves further investigation.
Article
We documented 17 white sturgeon Acipenser transmontanus spawning locations in the Snake River from the mouth to Lower Granite Dam (river lan 0 to 173). Spawning locations were determined by the collection of fertilized eggs on artificial substrates or in plankton nets. We collected 245 eggs at seven locations in McNary Reservoir, 22 eggs at three locations in Ice Harbor Reservoir, 30 eggs from two locations in Lower Monumental Reservoir, and 464 eggs at five locations in Little Goose Reservoir. All 17 locations were in high water velocity areas and between 1.0 and 7.0 lan downstream from a hydroelectric dam. The documentation of spawning areas is important because this habitat is necessary to maintain natural and viable populations.
Article
Estimates of spawning habitat for white sturgeons Acipenser transmontanus in the tailraces of the four dams on the lower 470 km of the Columbia River were obtained by using the Physical Habitat Simulation System of the U.S. Fish and Wildlife Service's Instream Flow Incremental Methodology to identify areas with suitable water depths, water velocities, and substrates. Rearing habitat throughout the lower Columbia River was assessed by using a geographic information system to identify areas with suitable water depths and substrates. The lowering of spring and summer river discharges from hydropower system operation reduces the availability of spawning habitat for white sturgeons. The four dam tailraces in the study area differ in the amount and quality of spawning habitat available at various discharges; the differences are due to channel morphology. The three impoundments and the free-flowing Columbia River downstream from Bonneville Dam provide extensive areas that are physically suitable for rearing young-of-the-year and juvenile white sturgeons.
Article
The Kootenai River white sturgeon Acipenser transmontanus has been isolated from other white sturgeon populations for over 10,000 years, Bonnington Falls in British Columbia, Canada, creating the isolation. Libby Dam, constructed in 1972, modified the flow and temperature regime of the river, which affected spawning and recruitment of white sturgeon. Kootenai River white sturgeon are only known to spawn in a reach near Bonners Ferry, Idaho, 100 km downstream from the dam. In 2 of 8 years of study, only 15 white sturgeon eggs were collected over gravel-cobble substrate. However, in the other 6 years, 1,193 eggs were collected over sand substrate; these areas usually exceeded 5 m in depth, were within the main channel, and had water velocities of 0.2-1.0 m/s and temperatures of 8.5-12°C. In general, these characteristics differed from optimum white sturgeon spawning habitat in the Columbia River, where velocities average 0.8 m/s, water temperatures are 12-17°C, and gravel-cobble substrate is available. Spawning over sand substrate might contradict survival strategies because white sturgeon have an adhesive egg to which sand adheres. Differences in spawning habitat may be an outcome of behavioral divergence or disruption to environmental cues but was probably caused by preferred habitat no longer being available. Recovery of Kootenai River white sturgeon will depend primarily on continuation of mitigated flows for spawning migrations, suitable spawning habitat, and ultimately survival of eggs and larvae. It is unknown at this time whether recent spawning alone will lead to sufficient recruitment to help recovery of the population, but if it does not recruit substantial year-classes, we believe consideration must be given to measures that would provide coarser spawning substrates and warmer water temperatures.
Article
A comprehensive program of sediment transport measurements was conducted along lower Fraser River, British Columbia, between 1966 and 1986. The data yield a detailed sediment budget. Annual total suspended loads at three stations are virtually identical, averaging 17×106tonnes/year(tyr-1). The suspended sand load is about 5.5×106tyr-1, about one third of the total. In the gravel bed reach of the river the sand behaves as wash load. Significant transport of gravel begins at Agassiz at a discharge of about 5000 m3 s-1. The annual gravel transport was estimated to be about 0.23×106tyr-1, only 1% of the total load. All of this material is deposited in the reach upstream of Mission. At Mission, sands finer than 0.177 mm make up more than 50% of the suspended sand load but are virtually absent from the sand bed. Therefore a portion of the sand load at Mission is wash load. The total bed material load here was estimated to be 3.0×106tyr-1, about 18% of the total sediment load. Virtually all of the bed material load was transported in intermittent suspension near the bed, less than 5% occurring as bed load. In the long term the suspended sand load upstream is approximately equal to the total sand load at Mission. However, within individual years some of the sand is stored within the reach temporarily and then reentrained later.
Article
White sturgeons Acipenser transmontanus were sampled in three lower Columbia River reservoirs from 1987 to 1991 to describe population dynamics, the ability of these stocks to sustain harvest, and differences among reservoir and unimpounded populations. Significant differences were observed among reservoirs in white sturgeon abundance, biomass, size composition, sex ratio, size of females at maturity, growth rate, condition factor, and rate of exploitation. No differences among reservoirs were detected in fecundity, natural mortality rate, or longevity, in part because of sampling difficulties. Recruitment rates and densities in reservoirs were inversely correlated with growth rate, condition factor, and size of females at maturity. Differences in population dynamics resulted in substantial differences in sustainable yields. Maximum yields per recruit were predicted at annual exploitation rates between 5 and 15%. Most characteristics of reservoir populations were less than or equal to optima reported for the unimpounded lower river; as a result, yield per recruit, reproductive potential per recruit, and the number of recruits were less in reservoirs than in the unimpounded river. Comparisons with pristine standing stocks suggest that the unimpounded river may approximate preimpoundment conditions for white sturgeon. We conclude that potential yield from impounded populations has been reduced by dam construction, which restricts populations to river segments that may not include conditions optimal for all life stages. Alternatives for enhancement of reservoir populations might include improved passage at dams, increased spring flow to improve spawning success, transplants from productive populations, hatchery supplementation, and more intensive harvest management.
Article
Spawning and rearing habitats used by white sturgeons Acipenser transmontanus were described from water temperature, depth, and velocity measurements and substrate types present at sites where eggs, larvae, young-of-the-year, and juveniles (ages 1–7) were collected. Spawning and egg incubation occurred in the swiftest water available (mean water column velocity, 0.8–2.8 m/s), which was within 8 km downstream from each of the four main-stem Columbia River dams in our study area. Substrates where spawning occurred were mainly cobble, boulder, and bedrock. Yolk-sac larvae were transported by the river currents from spawning areas into deeper areas with lower water velocities and finer substrates. Young-of-the-year white sturgeons were found at depths of 9–57 m, at mean water column velocities of 0.6 m/s and less, and over substrates of hard clay, mud and silt, sand, gravel, and cobble. Juvenile fish were found at depths of 2–58 m, at mean water column velocities of 1.2 m/s and less, and over substrates of hard clay, mud and silt, sand, gravel, cobble, boulder, and bedrock.
Article
River regulation imposes primary changes on flow and sediment transfer, the principal factors governing the alluvial channel regime. In this study, the effect of flow regulation is isolated from sediment delivery. Peace River (Q̄ = 1080m3s−1, increasing to 2110m3s−1 downstream) was regulated in 1967 for hydropower. The gravel-bed reach immediately downstream from the dam has become stable. Gravel accumulates at major tributary junctions, so the river profile is becoming stepped. Further downstream, the river has a sand bed. It can still transport sand, so morphological changes along the channel include both aggradation and channel narrowing by lateral accretation. In the gravel-bed Kemano River (Q̄ = 150m3s−1), the addition of water by diversion from another river caused degradation when additional bed material was entrained below the inflow point. However, the effect became evident only after many years, when a competent flood occurred. The short-term response was channel widening. The time-scale for the response depends on the size of the river and the nature and severity of regulation. In both rivers, significant adjustment will require centuries and will intimately involve the riparian forest.
Article
A survey of flows was conducted at a river confluence with coarse bed material. Bridges were installed on both tributaries, at the confluence and farther downstream on the receiving stream. At these stations, flow velocities were measured over a dense grid for seven conditions ranging from very low flows to the bankfull stage. Hydraulic geometry relationships established at all four stations revealed that flow is accelerated through the confluence as stage rises. At bankfull discharge, average velocity is 1.6 times higher at the confluence than on either tributary. Flow acceleration occurs at and above intermediate flow stages and is concentrated at the centre of a linear pool located at the confluence. The development of a zone of high shear stress is also associated with the cell of high flow velocity. Flow acceleration is dissipated at the exit of the pool where water surges over boulder ribs. The acceleration is not related to the development of flow separation zones as observed by Best and Reid (1984) for wide junction angles, nor is it explained by the reduction of the friction exerted by the banks. Acceleration is associated with the plan geometry of the confluence, with the lateral slopes which permit water to converge, and with a reduction in grain roughness at the confluence. Owing to the curvature of the tributary and to the acute angle of entry, relative power losses through the confluence decrease with increasing stages.