Post‐release movements and habitat use of robust redhorse transplanted to the Ocmulgee River,Georgia

• 1. Robust redhorse Moxostoma robustum is an imperiled, potadromous fish in the south‐eastern USA. Initial recovery efforts have focused on supplementing existing populations and establishing refugial populations through extensive stocking programmes. However, assessment of the success of these programmes has not yet been conducted, and there are few reports evaluating the effectiveness of such programmes with other potadromous species.
• 2. Radio telemetry was employed to assess the effectiveness of a stocking programme aimed at addressing whether stocked individuals would remain in an area free of introduced predators and ascertaining the ability of stocked fish to integrate into a resident population.
• 3. Hatchery‐reared robust redhorse were captured from refugial populations established in other river systems and were transferred to the Ocmulgee River, Georgia where a population of hatchery‐reared individuals and an unknown number of wild fish reside.
• 4. These transferred robust redhorse exhibited an exploratory phase for the first 3 months before adopting behaviour patterns, including spawning migrations, that were consistent with those reported for wild fish in other systems. However, some individuals seemed unable to locate suitable spawning habitat.
• 5. Approximately half of the radio‐tagged fish remained within the area free of introduced predators.
• 6. At least some radio‐tagged robust redhorse fully integrated into the resident population as evidenced by their presence in spawning aggregations with resident individuals.
• 7. The effectiveness of a stocking programme is dependent upon the ability of stocked individuals to integrate into an existing population or replicate the behaviour and functionality of a resident population. Evaluations of stocking programmes should incorporate assessments of behaviour in addition to surveys to estimate abundance and survivorship and genetic assessments of augmentation of effective population sizes.

Published in 2008 by John Wiley & Sons, Ltd.     

Seasonal movements with shifts in lateral and longitudinal habitat use by common bream,Abramis brama,in a heavily modified lowland river

Acoustic telemetry was used to investigate the longitudinal and lateral movements and distribution of adult common bream, Abramis brama (L.), over 43 months in a heavily modified lowland river in eastern England. A positive relationship between activity and temperature was found, with bream moving greater cumulative distances during the warmer months and distributed over a greater longitudinal proportion of the main channel. The occupancy of tributaries was related to temperature, with bream entering shallow tributaries during rising temperatures in the spring, whilst a deeper, slow‐flowing tributary was used more frequently during the cooler autumn/winter months. During the autumn, occupancy of this deeper tributary was positively related to flow rate in the main channel, suggesting that bream use this tributary for flow refuge. The functions of these behaviours are discussed along with potential management of heavily modified lowland rivers.     

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

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

Movements,behavior, and habitat utilization of yellowfin tuna (Thunnus albacares) in waters surrounding the Revillagigedo Islands Archipelago Biosphere Reserve,Mexico

The movements, behavior, and habitat utilization of yellowfin tuna, Thunnus albacares, following capture and release with archival tags in the Revillagigedo Islands Archipelago Biosphere Reserve (RIABR), Mexico, are described from analyses of 16 578 days of time‐series data, downloaded from 52 archival tags recovered from yellowfin (78–173 cm in length and 1.7–8.0 yr of age) at liberty from 93 to 1773 days ( = 411 days), collected during 2006–2012. An unscented Kalman filter model with sea‐surface temperature measurements integrated (UKFsst) was used to process the archival tag data sets to obtain improved estimates of geographic positions, most probable tracks (MPTs), and movement parameters. The MPTs indicate restricted movements, low levels of dispersion, and fidelity of yellowfin tuna to the RIABR. The median parameter estimates from the UKFsst model for errors in longitude (σ_x) and latitude (σ_y) were 0.46° and 1.84°, respectively, for directed movements (u and v) –0.05 NM day^?1 and –0.05 NM day^?1, respectively, and for dispersive movement (D) 117.99 NM² day^?1. Analyses of daily timed depth and temperature records resulted in the classification of the data into four distinct behaviors. There are significant differences among ages in the durations of Type I and Type II diving behaviors and in the daytime and nighttime vertical habitat utilization distributions. The oceanography surrounding the RIABR appears to have a profound influence on the movements, behavior, and habitat utilization of yellowfin in this area.     

A patch perspective on summer habitat use by brown trout Salmo trutta in a high plains stream in Wyoming, USA

Abstract –  We quantified the use of habitat patches by brown trout, Salmo trutta , during summer conditions in a plains stream in the western United States. A Global Positioning System was used to map discrete habitat patches (2–420 m²) consisting of macrophytes, wood accumulation, or deep water. Habitat use by brown trout was monitored by radio telemetry. Brown trout used habitat in a nonrandom manner with 99% of all daytime observations and 91% of all nighttime observations occurring in patches that consisted of combinations of deep water, wood accumulations or macrophytes even though such patches constituted only 9.8% of the available habitat. Brown trout used deep water almost exclusively during the day but broadened their habitat use at night. Most fish stayed within a large plunge pool created by a low-head dam. This pool supplemented the deep-water habitat that was naturally rare in our study area and illustrates how human modifications can sometimes create habitat patches important for stream fishes.     

Broad‐scale movements and pelagic habitat of the dusky shark Carcharhinus obscurus off Southern Australia determined using pop‐up satellite archival tags

We investigated the broad‐scale movements and pelagic habitats of large juvenile dusky sharks (Carcharhinus obscurus) off Southern Australia. Pop‐up satellite archival tags (PSATs) were deployed on three large juvenile dusky sharks (～2.2–2.6 m total length) for 6 months in Spencer Gulf during 2010. Tagged dusky sharks all migrated westward and across the Great Australian Bight (GAB) during autumn to offshore shelf waters off Western Australia. Estimated minimum distances travelled ranged from 1760 to 2736 km. Depths occupied by tagged dusky sharks ranged from the surface to 355 m. The most common thermal ranges occupied were 19–22°C. Broad‐scale movements of large juvenile dusky sharks across the continental shelves combined with periods of residency in semi‐protected gulf waters indicated that a multi‐jurisdictional management approach may be appropriate for this species.     

Large‐scale,seasonal habitat use and movements of yellow American eels in the St. Lawrence River revealed by acoustic telemetry

Large‐scale habitat use and movements of yellow American eels (Anguilla rostrata) from the St. Lawrence River were examined using acoustic telemetry from early summer to late fall in 2010 and 2011. Sixty‐seven eels were tagged, and their passage or presence was recorded using fixed acoustic arrays covering a 400 km distance along the St. Lawrence River and Estuary. Sixty‐four per cent of the 67 tagged eels were detected. Most eels were detected at only one array; the closest to their release location and at several occasions during the tracking period, suggesting a high proportion of freshwater residency in the upstream part of the St. Lawrence River. Downstream movements towards the brackish estuary (63–418 km distance) were demonstrated for 16.4% of the eels, particularly for those caught at the most downstream site that is close to the brackish estuary. Our results strongly suggest a lower activity of freshwater resident yellow eels during summer, a behaviour that may be related to day length, which defines time available for their nocturnal foraging. Indeed, yellow eels were detected primarily at night; no effect of moon phase was revealed. Movements in the vicinity of arrays (up to 116 km in the fluvial estuary) were suggested and smaller‐scale movements within Lac St. Louis were demonstrated, highlighting a yellow‐eel home range far more extensive than previously reported in smaller systems. Evidence for within‐season homing and site fidelity is also reported.     

Seasonal variation in habitat use by salmon, Salmo salar, trout, Salmo trutta and grayling, Thymallus thymallus, in a chalk stream

Abstract A portable multi‐point decoder system deployed in a tributary of the River Itchen, a southern English chalk stream, recorded the habitats used by PIT‐tagged juvenile salmon, Salmo salar L., trout, Salmo trutta L. and grayling, Thymallus thymallus L., with a high degree of spatial and temporal resolution. The fishes’ use of habitat was monitored at 350 locations throughout the stream during September/October 2001 (feeding period) and January/February 2002 (over‐wintering period). Salmon parr tended to occupy water 25–55 cm deep with a velocity between 0.4 and 1.0 m s^?1. During both autumn and winter, first year salmon (0+ group) were associated with gravel substrate during the daytime and aquatic weed at night. In autumn, 1+ salmon were strongly associated with hard mud substrates during the day and with marginal tree roots at night. In winter, they were located on gravel substrate by day and gravel and mud at night. Trout were associated with a greater range of habitats than salmon, generally occupying deeper and faster water with increasing age. During the autumn, 0+ trout were located along shallow (5–10 cm) and slow (?0.1–0.4 m s^?1) margins of the stream, amongst tree roots by day and on silty substrates at night. During winter the 0+ trout occupied silty substrates at all times. As age increased, trout increasingly used coarse substrates; hard mud, gravel and chalk, and weed at night. All age groups of grayling (0+, 1+ and 2+) tended to occupy hard gravel substrate at all times and used deeper and faster water with increasing age. The 1+ and 2+ groups were generally found in water 40–70 cm deep with a velocity between 0.3 and 0.5 ms^?1, whilst the 0+ groups showed a preference for shallower water with reduced velocity at night, particularly in the winter. There were greater differences in the habitats used between species and age groups than between the autumn and winter periods, and the distribution of fish was more strongly influenced by substrate type than water depth or velocity. The results are discussed in relation to the habitat requirements of mixed salmonid populations and habitat management.     

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

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

Summer habitat use of Arctic char (Salvelinus alpinus) in a small Arctic lake, monitored by acoustic telemetry

Abstract –  Acoustic technologies were applied to describe how landlocked Arctic char from Iqalugaajuruluit Lake, Baffin Island, interact with its lacustrine habitat. Acoustic data from the lake bottom was collected using sonar equipment and substrate types were verified with benthic grabs and mapped in a geographic information system. Arctic char movements during the open water period were recorded from char fitted with acoustic tags. The distribution of the tagged Arctic char in Iqalugaajuruluit Lake was dependent on fish size and related to abiotic factors such as depth, substrate type and depth/temperature, temporally. The volume of water with temperatures below 6 °C during the open water period may be a limiting factor for large char (>400 mm) in small Arctic lakes. The large piscivorous char are found most often in the deepest water over soft substrates and the smaller char which feed on varying proportions of invertebrates and fish were found most often over the more complex substrates such as boulders, pebbles and gravel.     

Living on the continental shelf edge: habitat use of juvenile shortfin makos Isurus oxyrinchus in the Great Australian Bight,southern Australia

We used satellite telemetry data to investigate the movement patterns and habitat use of juvenile shortfin makos Isurus oxyrinchus (Lamnidae) tagged in the Great Australian Bight, southern Australia. Tracking durations ranged from 49–672 days and six deployments were > 1 year. During winter and spring, some shortfin makos migrated to the tropical NE Indian Ocean and Coral Sea, and the Subtropical Front region. One shortfin mako undertook an extended migration of 25 550 km across the Indian Ocean. Areas characterized by sea‐mounts in the NE Indian Ocean, the oceanic Subtropical Front region, and the continental shelf edge (200‐m depth) and slope canyons were visited by several sharks. Juvenile shortfin makos used the outer continental shelf, the shelf edge, the slope and oceanic waters during migrations and mostly exhibited fidelity in the mid‐outer shelf, the shelf edge and slope habitats characterized by high bathymetric relief and oceanographic frontal gradients. Our findings highlighted that the continental shelf and slope and associated submarine canyons of the Great Australian Bight represent ecologically important habitats for juvenile shortfin makos. The findings of this study will be pertinent during future management processes for this highly migratory species in this Southern Hemisphere region.     

Movement ecology of imperilled fish in a novel ecosystem: River‐reservoir movements by razorback sucker and translocations to aid conservation

1. Reservoirs and associated river fragments are novel ecosystems not experienced by fishes in their evolutionary history, yet they are now commonplace across the globe. Understanding how fishes use these novel habitats is vital to conservation efforts in contemporary riverscapes.
2. Movement patterns of the endangered razorback sucker (Xyrauchen texanus) synthesized from tagging efforts in the upper Colorado River basin, USA, illustrate the applications of tagging technology and data sharing by multiple agencies to better understand the spatial ecology of large river fishes.
3. Tagging studies between 2014 and 2018 in Lake Powell and its two main tributary rivers, the Colorado (unfragmented) and San Juan (waterfall‐fragmented), were used to quantify movement of razorback sucker within this river–reservoir habitat complex. In addition, facilitated translocations of fish upstream of a waterfall barrier in the San Juan River were assessed in 2016–2017.
4. Extensive movement of fish occurred within and across river and reservoir habitats. Of 722 fish captured in the Colorado River arm of Lake Powell, 36% of re‐encounters occurred upstream in the Colorado or Green rivers, or fish dispersed through the reservoir and were detected in the San Juan River arm. Fourteen fish moved more than 600 km. In the San Juan arm of the reservoir, 29% and 20% of fish in 2017 and 2018, respectively, had moved ~30–40 km upstream below the waterfall in the San Juan River within a year. In 2016–2017, 303 fish were translocated upstream of the waterfall into the San Juan River, but 80% were re‐encountered downstream of the waterfall within a year.
5. Long‐distance movements by razorback sucker were common within and among rivers and reservoirs illustrating how large river fish, in general, might maintain population connectivity in highly altered ecosystems.

     

Short-term habitat use by young grayling, Thymallus thymallus L., under variable flow conditions in an experimental stream

Abstract  In an experimental stream containing available refuge zones, moderate and instantaneous flow variations did not cause high mortality or substantial increase in downstream migration of 2-month-old grayling, Thymallus thymallus L. Fish were able to react rapidly to spate simulations by a change in space utilization determined by changes in water velocity patterns. Reaction of fish to these experimental flow variations corresponded to a refuge strategy, i.e. seeking shelter and minimizing the distance to find it.     

Habitat use and movement of river blackfish (Gadopsis marmoratus R.) in a highly modified Victorian stream, Australia

Abstract –  Movement and habitat use of river blackfish ( Gadopsis marmoratus R.) was studied in a highly modified central Victorian stream (Birch Creek), Australia, using radio telemetry ( N  = 10) and mark–recapture ( N  = 113) between October 2001 to May 2002, and November to December 2002 respectively. Blackfish had a small home range of 10–26 m with strong affinity to a pool. However, small movements within a pool were common which resulted in relatively large cumulative movements. At a diel scale there were no significant differences in blackfish movement between day and night (Kruskal–Wallis test, P  = 0.95). Six of seven blackfish translocated 40 m upstream or downstream of their original positions returned within 48 h, suggesting strong affinity not only to a pool, but also to a small region within a pool. Blackfish utilised slow flowing (0–20 cm s⁻¹) and deep waters (40–60 cm). Blackfish were strongly associated with the instream cover habitats of undercut banks and boulders. Significant differences were recorded in instream cover and water velocity used by blackfish between day and night (Kruskal–Wallis test, P  = <0.01). At night blackfish used open areas with high water velocities whereas during the day blackfish used complex undercut banks with low water velocities.     

Movements by wild brown trout in a boreal river: response to habitat and flow contrasts

Abstract  Radio transmitters were implanted in wild brown trout, Salmo trutta L., in the River Måna at low summer water flows ( n  = 18), higher flow in summer ( n  =   20), and variable, peaking flows in autumn ( n  =   20), and tracked two to four times day and night for 4–5 weeks. Individuals were caught and released in a 4-km uniformly channelised section, and in a 4-km natural diverse river section. Substantial individual variation in home range and total movement (924–85 818 m² and 295–7014 m) suggested flexibility to adapt to local environmental conditions. Fish were stationary most of the time (median movement 0 m), but some individuals undertook few and apparently sporadic longer movements, sometimes involving shifts in home range. No consistent diurnal pattern in movements was found. Trout in the uniform habitat section appeared to have larger home ranges and moved more than trout in the natural section. Differences were, however, not statistically significant in most comparisons, due to large individual variation. Similarly, larger home ranges and movements between trials related to higher flow were found, but differences were generally not significant. No consistent effects of sudden, extreme peaking flows on area use or movements by the brown trout were observed.     

Denil fishway utilization patterns and passage of several warmwater species relative to seasonal, thermal and hydraulic dynamics

Abstract – Two different Denil fishways on the Grand River, Ontario, were used as check-points to evaluate the upstream movement of fishes past a low-head weir and to examine the proportions and inferred swimming performance of non-salmonid warmwater fishes that used each fishway type. Traps installed at fishway exits were used to collect fish during 24-hour sampling periods, over 40–51 days each year, from 1995 to 1997. Passage rates, size selectivity, water temperature, water velocity and turbidity for the periods of maximum passage for each year were examined. General species composition from trap samples shifted from catostomids to cyprinids to ictalurids to percids and centrarchids, with some overlap, as water temperatures increased from 8 °C to 25 °C in the spring and early summer. Water depths, and therefore water velocities in each fishway, were independent of river discharge due to variable accumulations of debris on upstream trash-racks. Relationships between the water velocity and the swimming and position-holding abilities of several species emerged. Turbidity was directly related to river discharge and precipitation events, and many species demonstrated maximum fishway use during periods of increased turbidity. This study 1) provided evidence of strongly directional upstream movements among several species that were previously considered non-migratory and 2) describes physical and hydraulic conditions during fishway use for 29 non-salmonid fish species.     

Rehabilitation of brown trout, Salmo trutta, habitat damaged by riparian grazing in an English chalkstream

Abstract  Rehabilitation trials involving riparian fencing and limited pool excavation were conducted on the River Piddle and Devil's Brook, Dorset, England, which had been degraded by intensive riparian grazing. In one trial, based on two short (94 and 99 m) treated sections and two control sections, brown trout, Salmo trutta L., numbers were monitored from 1994 (pre-treatment) to 2000. In a second trial from 1996 (pre-treatment) until 2000, trout numbers were monitored in 900 m and 1400 m treated sections. After rehabilitation, juvenile trout numbers increased in the two short sections (Trial 1) but fell in one of the long sections. Adult numbers also increased markedly in the two short-treated sections relative to the controls and they increased markedly in one of the long sections despite a reduction in juveniles. Marking of trout in the short sections showed that they selected the rehabilitated habitat in preference to the control habitat and that immigration was the main source of adult trout, as it must also have been in the 1400 m section. While the results indicate that improvements can be made to adult trout habitat, more research is required on the impact on juvenile production before the impact of such work on the true population can be established.     

Effects of food supply and stream physical characteristics on habitat use of a stream‐dwelling fish

Identifying the environmental factors that affect freshwater fish can be crucial for their conservation and management. Despite the widespread investigation of relationships between fish habitat use and environmental variables, there is a paucity of knowledge on how abiotic and biotic factors jointly influence stream fish habitat use. Three New Zealand South Island streams were selected to investigate the habitat preference of a stream‐dwelling galaxiid, banded kokopu (Galaxias fasciatus). Fish abundance in several permanent pools was determined by spotlighting at night once a month from June 2008 to May 2009. Drifting invertebrates and key physical features of each pool were measured at the time of fish sampling. An information‐theoretic approach (AIC) indicated that the most parsimonious candidate model to predict banded kokopu biomass was the one that included pool area, undercut banks, water velocity, overhanging vegetation, invertebrate drift density and an interaction term between invertebrate drift density and water velocity. Banded kokopu biomass was positively related to pool area, undercut banks, overhanging vegetation and invertebrate drift density. Our study suggests that fish resource use patterns need to be understood in the context of multiple interacting ecological factors, including prey abundance.