Quantifying the fine-scale behaviour of spawning run river lamprey (Lampetra fluviatilis) approaching a low-head weir retrofitted with studded tiles

Fish passes (or fishways) designed to mitigate for the impeded movement of migratory fish at anthropogenic structures (such as dams and weirs) often function poorly. This is particularly the case for anguilliform species such as lamprey (Petromyzon spp. and Lampetra spp.). Poor swimming capability (in comparison to e.g. salmonids) and a lack of understanding of behaviour in response to hydrodynamic cues are considered key reasons limiting the performance of mitigation measures. A field study employing Passive Integrated Transponder (PIT) and fine-scale (sub-metre) acoustic telemetry was conducted on the River Derwent (Yorkshire, UK) in Winter (November – December) 2017. The aim of the study was to assess river lamprey behaviour and passage at a low-head weir retrofitted with studded tiles designed to aid upstream movement. In this talk, the acoustic telemetry data will be presented, outlining fine-scale behaviour and weir approach routes of lamprey in relation to hydrodynamics that were measured using a remotely operated Acoustic Doppler Current Profiler. How this data can be quantified into “behavioural rules” to parameterise Agent Based Models will be discussed and examples provided. Such models will enable better predictions of fish movements to be made as they encounter anthropogenic structures and guide the design of more effective mitigation measures, such as fish passage and screening systems

Session C7: Tricky Little Lampreys! Efficacy of an Unmodified and Modified Super-Active Baffle Fish Pass for European River Lamprey (Lampetra Fluviatilis)

Abstract: Achieving good upstream passage of lampreys, a threatened group of serpentine fishes, remains a problem. The ability of European river lamprey (Lampetra fluviatilis) to pass a Crump weir using a 15% gradient Larinier superactive baffle fish pass during their upstream spawning migration was tested. This type of fish pass has become widespread in Europe in the last two decades, but its efficiency for river lamprey is unknown. River lamprey were PIT tagged (n=350) PIT, a subsample were acoustic tagged (n=31), and all were released downstream in batches in Oct-Dec 2013. Telemetry arrays were installed in the pass (PIT) and river (acoustic) and ran throughout the migration period. Attraction efficiency into the fishway (estimated at 90.1%) was good and half of lampreys entered within 24 h of release, but only one lamprey successfully ascended the pass (0.3% passage efficiency), despite many entering repeatedly. Out of 29 acoustic tagged lamprey that visited the weir, four (13.8%) passed the weir directly. The fishway was unsuitable for river lamprey over a wide range of flows. The pass was modified by addition of vertically mounted peg-and-slot tiles, interrogated at the entrance and exit by PIT telemetry and retested in winter 2014- 15. There was an increase in passage success. Preliminarily, out of 197 river lamprey PIT tagged Oct-Dec 2014, 184 (93.4%) were logged at the fishway entrance. 74 (40.2%) entered the tiles at the downstream end, of which 14 (18.9%) swam up through the tiles successfully. Twelve lamprey (6.5% passage efficiency) were logged at the upstream exit of the pass. Reduced flow velocity in combination with increased availability of resting habitat within the tiles may increase the passage efficiency of this type of fish pass for river lamprey. Although increased, passage efficiency, after placement of the tiles, is still considered far from optimal

Over 200,000 kilometers of free-flowing river habitat in Europe is altered due to impoundments

European rivers are disconnected by more than one million man-made barriers that physically limit aquatic species migration and contribute to modification of freshwater habitats. Here, a Conceptual Habitat Alteration Model for Ponding is developed to aid in evaluating the effects of impoundments on fish habitats. Fish communities present in rivers with low human impact and their broad environmental settings enable classification of European rivers into 15 macrohabitat types. These classifications, together with the estimated fish sensitivity to alteration of their habitat are used for assessing the impacts of six main barrier types (dams, weirs, sluices, culverts, fords, and ramps). Our results indicate that over 200,000 km or 10% of previously free-flowing river habitat has been altered due to impoundments. Although they appear less frequently, dams, weirs and sluices cause much more habitat alteration than the other types. Their impact is regionally diverse, which is a function of barrier height, type and density, as well as biogeographical location. This work allows us to foresee what potential environmental gain or loss can be expected with planned barrier management actions in rivers, and to prioritize management actions

Body Composition Is a Predictor for Postoperative Complications After Gastrectomy for Gastric Cancer:a Prospective Side Study of the LOGICA Trial

PURPOSE: There is a lack of prospective studies evaluating the effects of body composition on postoperative complications after gastrectomy in a Western population with predominantly advanced gastric cancer. METHODS: This is a prospective side study of the LOGICA trial, a multicenter randomized trial on laparoscopic versus open gastrectomy for gastric cancer. Trial patients who received preoperative chemotherapy followed by gastrectomy with an available preoperative restaging abdominal computed tomography (CT) scan were included. The CT scan was used to calculate the mass (M) and radiation attenuation (RA) of skeletal muscle (SM), visceral adipose tissue (VAT), and subcutaneous adipose tissue (SAT). These variables were expressed as Z-scores, depicting how many standard deviations each patient’s CT value differs from the sex-specific study sample mean. Primary outcome was the association of each Z-score with the occurrence of a major postoperative complication (Clavien-Dindo grade ≥ 3b). RESULTS: From 2015 to 2018, a total of 112 patients were included. A major postoperative complication occurred in 9 patients (8%). A high SM-M Z-score was associated with a lower risk of major postoperative complications (RR 0.47, 95% CI 0.28–0.78, p = 0.004). Furthermore, high VAT-RA Z-scores and SAT-RA Z-scores were associated with a higher risk of major postoperative complications (RR 2.82, 95% CI 1.52–5.23, p = 0.001 and RR 1.95, 95% CI 1.14–3.34, p = 0.015, respectively). VAT-M, SAT-M, and SM-RA Z-scores showed no significant associations. CONCLUSION: Preoperative low skeletal muscle mass and high visceral and subcutaneous adipose tissue radiation attenuation (indicating fat depleted of triglycerides) were associated with a higher risk of developing a major postoperative complication in patients treated with preoperative chemotherapy followed by gastrectomy. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s11605-022-05321-0

Short-term effects of low-head barrier removals on fish communities and habitats

Barrier removal is increasingly being seen as the optimal solution to restore lotic habitat and fish communities, however, evidence of its efficacy is often limited to single sites or catchments. This study used a before–after methodology to examine the short-term (average, 541 days) effects of low-head (0.1–2.9 m) barrier removal at 22 sites distributed across Denmark and northern England on fish density, community, and river habitat responses. Following barrier removal, changes in the aquatic habitat were observed, such that the area immediately upstream of the former barrier location became shallower, with larger substrate and faster flow conditions. The reinstatement of this habitat was especially valuable in Danish streams, where these habitat features are rare, due to the naturally low gradients. Across all 22 sites fish species richness and diversity was similar before and after removal of barriers, likely because of the short study timescale (1–2 years). Across all sites combined, there was an increase in total fish density following barrier removal. A large increase in salmonid (Salmo trutta and Salmo salar) densities following barrier removal occurred at 7 out of 12 Danish sites. No similar response in salmonid density was observed at any of the UK sites which were mostly characterized by high channel gradients and short ponded zones. Two UK barrier removal sites showed marked increases in density of non-salmonid fish species. This study suggests that the removal of low-head barriers can be an effective method of restoring lotic habitats, and can lead to positive changes in fish density in the former ponded zone. The short-term effect of small barrier removal on the fish community is more variable and its effectiveness is likely to be determined by wider riverine processes

Evaluating the effectiveness of a Larinier super active baffle fish pass for European river lamprey Lampetra fluviatilis before and after modification with wall-mounted studded tiles

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Evaluating the effectiveness of a Larinier super active baffle fish pass for European river lamprey Lampetra fluviatilis before and after modification with wall-mounted studded tiles

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Enhancing the upstream passage of river lamprey at a microhydropower installation using horizontally-mounted studded tiles

Passage performance of upstream-migrating lamprey (Lampetra fluviatilis) was compared between sections of a Crump flow-gauging weir with and without studded tiles, and at a bottom-baffle fishway, on the River Derwent, England. The effects of microhydropower operation on attraction to multiple routes were also studied. Studded tiles were fixed horizontally on the weir face near the right bank, forming a 1 m wide treatment route, neighboured by a tileless control route. A bottom-baffle fishway was present at the right bank, alongside the hydropower tailrace. Two further weir-face control routes at the left bank, in combination with those on the right side, enabled comparison of lamprey attraction relative to the weir flow. Downstream and upstream ends of the right-hand weir-face routes, and of the fishway, downstream ends of the left-hand weir face routes, and the entrance of the hydropower tailrace area were instrumented with PIT antennas (n = 9 total). Of 395 PIT-tagged lamprey, released 0.52 rkm downstream of the weir on 10 separate dates in early winter 2017 (turbine on for 21/43 days of study period), 363 (91.9%) were detected by at least one of the antennas (median [IQR] minimum delay at weir: 15.0 [7.4–21.4] days). All lamprey detected at the left-bank antennas (attraction efficiency AE: 255/395 [64.6%]) were also detected elsewhere. The fishway was ineffective (AE: 343/395 [86.8%]; passage efficiency PE: 5/343 [1.5%]). While lamprey were more attracted towards the control relative to the adjacent tiled route, a higher number of fish traversed the weir using the latter (AE tiled route: 172/395 [43.5%]; PE tiled route: 44/172 [25.6%]; AE control route: 257/395 [65.1%]; PE control route: 22/257 [8.6%]). Lamprey were attracted towards the right half of the channel when the turbine was running, as only n = 88/4190 (2.1% of total attempts) detections were made at the two left-bank control antennas in the turbine-on condition, compared to 2775/13,029 (21.3%) at the same two antennas when the turbine was off. While improved passage efficiency was achieved using surface-mounted studded tiles, further in situ evaluations are needed to optimize their performance

River connectivity restoration for upstream‐migrating European river lamprey: The efficacy of two horizontally‐mounted studded tile designs

Many rivers are heavily fragmented, resulting from anthropogenic cross‐channel structures. Cost‐effective solutions are needed to restore habitat connectivity for migratory fishes, including those of conservation concern, such as the European river lamprey (Lampetra fluviatilis). Studded material is becoming increasingly used as a low‐cost retrofit solution for lamprey passage at sloping weirs, although little is known about the efficacy of the material or what stud arrangements may be most effective. This study tested whether expanding a single‐density studded tile (SDT) lane from 1 to 2‐m width increased passage success (nreleased = 133), and also compared the passage performance between a SDT lane and a dual‐density studded tile (DDT) lane (nreleased = 115) at a sloping weir, using PIT telemetry. No passage was recorded (nattempted = 89) at the 2‐m wide SDT lane, but 61.6% (npassed/attempted = 53/86) passed using DDT/SDT lane combination. However, increased passage efficiency was likely a result of high river flow (Q2.0‐Q30.6) during DDT/SDT comparison versus low (Q8.3‐Q88.5) while the 2‐m wide SDT lane was employed. There was no evidence that passage occurred using solely one stud configuration. It is, therefore, hypothesised that passage of river lamprey at weirs is more dependent on flow regime than the provision of either stud configuration. However, with 46.1% (npassed/released = 53/115) of those released during DDT/SDT comparison passing on the instrumented section (10.5% of weir face), the provision of studded tiles may aid in lamprey passage at high flows, presumably as the tiles generate a low‐velocity boundary layer that can be utilised as lamprey swim above the studs