Diel and seasonal movements of the critically endangered European eel

The critically endangered European eel is declining throughout its range and more information on which to base management plans is necessary. Here we present data collected by electrofishing and PIT telemetry on the habitat use and movements of eel in an English chalk stream in Dorset, southern UK. Eel were sampled quarterly for three years and movements between the main river and a side stream monitored by an in situ PIT detector. Eel abundance was highest in the side stream during summer and autumn and movement between the main river and side stream was greatest during spring, summer and autumn. Eel demonstrated nocturnal movements in/out of the side stream during spring and summer, however this diel pattern was not evident in autumn. The study demonstrates continual use of the connected floodplain by eel, underlining the importance of lateral connectivity to floodplain habitats to the species. Connectivity can be modified or lost by a number of anthropogenic activities such as hydropower and road culverts, but in many cases these can be avoided by proper and sound management. Key words: behaviour, Anguilla anguilla, movement, river connectivity, floodplain.Døgn- og sesongmessige vandringer hos den truede Europeiske ålen. Den Europeiske ålen(ål) er truet over hele dets utbredelsesområde og mer kunnskap om artens biologi og adferd er nødvendig for bedre forvaltning av arten. I denne artikkelen presenterer vi data for habitatbruk og forflytninger av ål i en kalkelv i Dorset, Sør-England basert på omfattende elektrofiske og PIT telemetri. Ål ble fanget fire ganger pr år og forflytninger mellom hovedelv og sidekanaler ble overvåket med hjelp av in situ PIT detektor i en periode på tre år. Det var høyeste forekomst av ål i sidekanalene om sommeren og høsten og det var omfattende forflytninger av ål mellom hovedelva og sidekanalene under vår, sommer og høst. Ålen hadde nattlige vandringer inn og ut av sidekanalene under vår og sommer, men denne døgn adferden var ikke tydelig om høsten når blankål startet sin utvandring mot sjøen. Studien demonstrerer ålen sin kontinuerlige bruk av flomområder og kanaler, og understreker viktigheten av å opprettholde forbindelsene fra hovedelva til disse habitatene for denne arten. Vannveier for fisk kan bli påvirket eller tapt ved en rekke antropogene aktiviteter slik som kraftutbygging og vei kulverter, men i en flere tilfeller kan dette ungåes ved god planlegging og kompetanse om fiskens adferd.publishedVersio

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

Stakeholders' knowledge of threatened freshwater fishes and their involvement in fishery value chains in order to assist conservation in developing countries

Introduction: Improved conservation of exploited freshwater biodiversity is an increasing priority globally, but in developing countries there is often little insight of stakeholder attitudes within the value chains through which exploited species are passed, upon which to make informed management decisions. Methods: We determined knowledge concerning threatened freshwater fishes in Bangladesh by key stakeholder groups (fishermen, faria agents, commission agents, retailers and consumers; n = 485 respondents) and their participation level in the threatened fish value chain. We also determined factors affecting local ecological knowledge and participation in the value chain. Results and discussion: The highest mean number of threatened fish species (4.8 ± 3.5% of species) was identified by the fishermen group, whereas consumers identified fewest (0.5 ± 1.1% of species). All respondent groups participated in the threatened fish value chain and their participation varied across respondent groups. 45.3% of the total number of threatened fish species appeared in the value chain. Participation level was highest for commission agents, involved in the trade of 21.5 ± 4.2% of threatened fish species, and lowest for consumers (7.4 ± 6.5% of threatened species). For fishermen, the principal component “experience-income-age” and the interaction between education and financial loan factors affected fishers' participation in the threatened fish value chain positively whereas, this was negatively affected by their knowledge level of threatened fishes. This study reveals the poor knowledge of stakeholder groups regarding threatened fishes, but establishes their active participation in the value chain of these species in Bangladesh. With limited resources for conservation of threatened species in many developing countries, it is very risky to implement commonly used in-situ conservation methods (e.g., habitat quality improvement) without fuller buy-in from the stakeholders. Conclusions: We recommend specific protection laws for threatened fishes and awareness building campaigns for stakeholder groups to ensure minimum impact to threatened fish species. As overharvesting is a major cause of threatened fish species decline, such training programmes should be designed for fishers in developing regions. Education programmes on threats to ecosystems and biodiversity should be prioritized in schools and fishing communities. In addition, regular monitoring for protected species at harvesting sites and fishing markets should be ensured

Convolutional Neural Networks Facilitate River Barrier Detection and Evidence Severe Habitat Fragmentation in the Mekong River Biodiversity Hotspot

Construction of river infrastructure, such as dams and weirs, is a global issue for ecosystem protection due to the fragmentation of river habitat and hydrological alteration it causes. Accurate river barrier databases, increasingly used to determine river fragmentation for ecologically sensitive management, are challenging to generate. This is especially so in large, poorly mapped basins where only large dams tend to be recorded. The Mekong is one of the world's most biodiverse river basins but, like many large rivers, impacts on habitat fragmentation from river infrastructure are poorly documented. To demonstrate a solution to this, and enable more sensitive basin management, we generated a whole‐basin barrier database for the Mekong, by training Convolutional Neural Network (CNN)–based object detection models, the best of which was used to identify 10,561 previously unrecorded barriers. Combining manual revision and merged with the existing barrier database, our new barrier database for the Mekong Basin contains 13,054 barriers. Existing databases for the Lower Mekong documented under ∼3% of the barriers recorded by CNN combined with manual checking. The Nam Chi/Nam Mun region, eastern Thailand, is the most fragmented area within the basin, with a median [95% CI] barrier density of 15.53 [0.00–49.30] per 100 km, and Catchment Area‐based Fragmentation Index value, calculated in an upstream direction, of 1,178.67 [0.00–6,418.46], due to the construction of dams and sluice gates. The CNN‐based object detection framework is effective and potentially can transform our ability to identify river barriers across many large river basins and facilitate ecologically‐sensitive management

Catchment-wide interactive effects of anthropogenic structures and river levels on fish spawning migrations

Worldwide, rivers are extensively fragmented by anthropogenic structures, reducing longitudinal connectivity, inhibiting migration and leading to severe declines in many fish populations, especially for diadromous species. However, few studies have determined the effects of annual differences in hydrology on catchment penetration past barriers to spawning habitats. We investigated the upstream spawning migration of 120 (n = 61 & 59) acoustic tagged river lamprey (Lampetra fluviatilis) across two contrasting (dry and wet) years in the River Yorkshire Ouse, England. Overall, significantly more lamprey reached spawning habitat (76% vs 39%) and penetrated significantly further upstream (median [km] from release, 53.9 vs 16.8) in the wet year than the dry year. Passage at weirs was almost exclusively during elevated river levels, which directly and collectively influenced catchment-wide distribution, especially in the dry year. Indeed, higher proportions entered two upper tributaries in the wet year (9.8% vs 27.1% and 9.8% vs 30.5%), due to increased passage efficiencies at the two main river weirs (60.5–87.5% and 54.5–83.8%), and reached assumed spawning locations 66.5% and 10.9% quicker. By contrast, there was no difference in numbers of lamprey entering, or time taken to arrive at assumed spawning location, in the two lower river tributaries between years. Our study supports the landscape-scale paradigm for ecosystem restoration because of the observed catchment-level effects of hydrology and barrier distribution on fish migration. Connectivity restoration for migratory fish should be implemented at a catchment scale, with planning incorporating spatial information regarding accessibility to key habitats to reap the largest gains

Effects of sex hormones on vascular reactivity in boys with hypospadias

Background: Arteries from boys with hypospadias demonstrate hypercontractility and impaired vasorelaxation. The role of sex hormones in these responses in unclear. Aims: We compared effects of sex steroids on vascular reactivity in healthy boys and boys with hypospadias. Methods: Excess foreskin tissue was obtained from 11 boys undergoing hypospadias repair (cases) and 12 undergoing routine circumcision (controls) (median age [range], 1.5 [1.2-2.7] years) and small resistance arteries were isolated. Vessels were mounted on wire myographs and vascular reactivity was assessed in the absence/presence of 17β-estradiol, dihydrotestosterone (DHT), and testosterone. Results: In controls, testosterone and 17β-estradiol increased contraction (percent of maximum contraction [Emax]: 83.74 basal vs 125.4 after testosterone, P < .0002; and 83.74 vs 110.2 after estradiol, P = .02). 17β-estradiol reduced vasorelaxation in arteries from controls (Emax: 10.6 vs 15.6 to acetylcholine, P < .0001; and Emax: 14.6 vs 20.5 to sodium nitroprusside, P < .0001). In hypospadias, testosterone (Emax: 137.9 vs 107.2, P = .01) and 17β-estradiol (Emax: 156.9 vs 23.6, P < .0001) reduced contraction. Androgens, but not 17β-estradiol, increased endothelium-dependent and endothelium-independent vasorelaxation in cases (Emax: 77.3 vs 51.7 with testosterone, P = .02; and vs 48.2 with DHT to acetylcholine, P = .0001; Emax: 43.0 vs 39.5 with testosterone, P = .02; and 39.6 vs 37.5 with DHT to sodium nitroprusside, P = .04). Conclusion: In healthy boys, testosterone and 17β-estradiol promote a vasoconstrictor phenotype, whereas in boys with hypospadias, these sex hormones reduce vasoconstriction, with androgens promoting vasorelaxation. Differences in baseline artery function may therefore be sex hormone-independent and the impact of early-life variations in androgen exposure on vascular function needs further study

Vascular dysfunction and increased cardiovascular risk in hypospadias

Aims Hypogonadism is associated with cardiovascular disease. However, the cardiovascular impact of hypogonadism during development is unknown. Using hypospadias as a surrogate of hypogonadism, we investigated whether hypospadias is associated with vascular dysfunction and is a risk factor for cardiovascular disease. Methods and results Our human study spanned molecular mechanistic to epidemiological investigations. Clinical vascular phenotyping was performed in adolescents with hypospadias and controls. Small subcutaneous arteries from penile skin from boys undergoing hypospadias repair and controls were isolated and functional studies were assessed by myography. Vascular smooth muscle cells were used to assess: Rho kinase, reactive oxygen species (ROS), nitric oxide synthase/nitric oxide, and DNA damage. Systemic oxidative stress was assessed in plasma and urine. Hospital episode data compared men with a history of hypospadias vs. controls. In adolescents with hypospadias, systolic blood pressure (P = 0.005), pulse pressure (P = 0.03), and carotid intima-media thickness standard deviation scores (P = 0.01) were increased. Arteries from boys with hypospadias demonstrated increased U46619-induced vasoconstriction (P = 0.009) and reduced acetylcholine-induced endothelium-dependent (P < 0.0001) and sodium nitroprusside-induced endothelium-independent vasorelaxation (P < 0.0001). Men born with hypospadias were at increased risk of arrhythmia [odds ratio (OR) 2.8, 95% confidence interval (CI) 1.4–5.6, P = 0.003]; hypertension (OR 4.2, 95% CI 1.5–11.9, P = 0.04); and heart failure (OR 1.9, 95% CI 1.7–114.3, P = 0.02). Conclusion Hypospadias is associated with vascular dysfunction and predisposes to hypertension and cardiovascular disease in adulthood. Underlying mechanisms involve perturbed Rho kinase- and Nox5/ROS-dependent signalling. Our novel findings delineate molecular mechanisms of vascular injury in hypogonadism, and identify hypospadias as a cardiovascular risk factor in males. Key question Is hypospadias associated with vascular dysfunction? Key finding Boys with hypospadias have evidence of hypercontractility and impaired vasodilation secondary to increased Rho kinase activation and oxidative stress. This leads to raised systolic blood pressure in adolescence and increased risk of admission to hospital for cardiovascular diseases in adulthood. Take-home message Hypospadias is a risk factor for cardiovascular dysfunction in males