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The interconnectedness of adjacent freshwater and terrestrial ecosystems results in 'tangled‐webs', where the cross‐boundary exchange of materials results in energy flows that provide critical resources for ecosystem productivity. However, these energy flows can be disrupted by anthropogenic activities, resulting in modified ecosystem functioning.A ubiquitous anthropogenic activity in fresh waters is recreational angling. Five major angling activities can disrupt the structure of the 'tangled‐web' to produce an 'angled‐web' (a tangled food web that is modified by angling activities). (1) Fish stocking increases the number and species available to exploit, but the increased fish abundances can have strong top‐down effects and disrupt reciprocal prey subsidies. Following capture, fish are either (2) harvested or (3) released alive ('catch‐and‐release0'); both can both drive eco‐evolutionary changes that can modify food‐web structure. Where fish are exploited using baited hooks, (4) the release of 'ground‐bait' is used as a fish attractant; its composition of novel protein and carbohydrate sources form novel trophic links in the food web and can accelerate eutrophication. Some angling styles also require (5) riparian and in‐stream vegetation to be cleared to minimise gear fouling, potentially modifying fish spawning and nursery areas.We suggest that each of these angling impacts (and their interactions) can contribute to transforming the 'tangled web' into an 'angled‐web', with the strength and direction of the transformation dependent on angling pressure, prevailing fishery practices, regulations and management, and the extent of the interaction effects of the activities. These interactions and their impacts will vary globally given angling methods, practices and regulations differ across the world.We argue that, in this era of substantial environmental change driven by climate change, habitat loss and nutrient enrichment of fresh waters, the extent to which angling impacts food webs should not be overlooked and underappreciated. We emphasise that when freshwater angling activities are poorly managed and/or unregulated, they can strongly modify the interconnectedness between terrestrial and freshwater food webs. [ABSTRACT FROM AUTHOR]

A general framework is presented that should enhance our understanding of how intrinsic factors, such as body size, and extrinsic factors, such as climate, affect the dynamics and demographics of fish populations. Effects of intrinsic factors, notably studies relating juvenile Atlantic salmon Salmo salar body size to their probability to return as an adult, are often context‐dependent and anecdotal, due to data constraints. By merit of its flexible specification, this framework should admit datasets with a range of situation‐specific nuances, collected using different approaches, and thereby deliver more general and robust findings for more effective population management. [ABSTRACT FROM AUTHOR]

Populations of fishes provide valuable services for billions of people, but face diverse and interacting threats that jeopardize their sustainability. Human population growth and intensifying resource use for food, water, energy and goods are compromising fish populations through a variety of mechanisms, including overfishing, habitat degradation and declines in water quality. The important challenges raised by these issues have been recognized and have led to considerable advances over past decades in managing and mitigating threats to fishes worldwide. In this review, we identify the major threats faced by fish populations alongside recent advances that are helping to address these issues. There are very significant efforts worldwide directed towards ensuring a sustainable future for the world's fishes and fisheries and those who rely on them. Although considerable challenges remain, by drawing attention to successful mitigation of threats to fish and fisheries we hope to provide the encouragement and direction that will allow these challenges to be overcome in the future. [ABSTRACT FROM AUTHOR]

OBJECTIVE: To assess the association between delivery room (DR) continuous positive airway pressure (CPAP) and pneumothorax (PT) in term newborns. METHODS: Two studies performed in community hospitals used data extracted from computerized records of term newborns. Infants receiving positive pressure ventilation in the DR were excluded. Tabulated data included receipt of DR CPAP, PT on the day of birth, and gestational age (GA). In a case-control study from 2001–2013, infants with PT were compared to controls without PT but with respiratory distress or hypoxia persisting from birth for receipt of DR CPAP. In a cohort study from 2014–2016, infants receiving and not receiving DR CPAP were compared for the incidence of PT. RESULTS: In the case-control study, data were obtained for 169 cases and 850 controls. Compared to controls, PT infants were more likely to have received DR CPAP (16.8% vs. 40.2%, respectively, P < 0.001). Logistic regression revealed DR CPAP (Adjusted Odds Ratio [AOR] = 3.30, 95% confidence interval [CI] = 2.31, 4.72, P < 0.001) and GA (AOR= 1.21, 95% CI = 1.05, 1.39, P = 0.009) to be independent predictors of early PT. In the cohort study, PT was observed in 0.1% of 9255 control infants not receiving DRCPAP and 4.8% of 228 infants receiving DR CPAP (P < 0.001). In logistic regression analyses, DR CPAP significantly predicted PT (OR = 59.59, 95% CI = 23.34, 147.12, P < 0.001) and remained a significant predictor of PT after controlling for gestational age. CONCLUSION: Respiratory conditions treated with CPAP in delivery rooms are associated with increased risk of PT. A cause-and-effect relationship between CPAP and PT cannot be claimed in this study. Further research is needed to better understand this relationship. [ABSTRACT FROM AUTHOR]

Populations of generalist species often comprise of smaller sub-sets of relatively specialized individuals whose niches comprise small sub-sets of the overall population niche. Here, the role of parasite infections in trophic niche specialization was tested using five wild fish populations infected with the non-native parasite Ergasilus briani, a copepod parasite with a direct lifecycle that infects the gill tissues of fish hosts. Infected and uninfected fishes were sampled from the same habitats during sampling events. Prevalence in the host populations ranged between 16 and 67%, with parasite abundances of up to 66 parasites per fish. Although pathological impacts included hyperplasia and localized haemorrhaging of gill tissues, there were no significant differences in the length, weight and condition of infected and uninfected fishes. Stable isotope analyses (δ13C, δ15N) revealed that the trophic niche of infected fishes, measured as standard ellipse area (i.e. the isotopic niche), was consistently and significantly smaller compared with uninfected conspecifics. These niches of infected fishes always sat within that of uninfected fish, suggesting trophic specialization in hosts. These results suggested trophic specialization is a potentially important non-lethal consequence of parasite infection that results from impaired functional traits of the host. [ABSTRACT FROM AUTHOR]

The anadromous sea lamprey Petromyzon marinus native range extends across the Northern Atlantic and includes much of Europe. Their complex lifecycle, involving freshwater spawning, juveniles (ammocoetes) that remain in freshwater for up to eight years, and adults migrating to sea before returning to reproduce, means native populations in Europe are threatened by multiple stressors, especially migration blockages and habitat loss. This has resulted in population declines across their European range, despite their ecological, evolutionary, and economic significance. Information on their population demography and long-term patterns are also scarce, with focus primarily on their ammocoete freshwater phase. This is inhibiting the development of biological reference points for utilization in population monitoring programs. In the Great Lakes of North America, however, P. marinus is invasive and the high damage caused to commercial fisheries resulted in their populations being controlled through a long-term, multi-method and integrated research and management approach over the last 40 years, with the development and application of a range of novel methods. Successful knowledge transfer to Europe could therefore facilitate the monitoring of threatened populations and develop new conservation actions, including modifying migration blockages to facilitate passage, implementing adult trapping programs, and applying pheromone treatments to manipulate adult movements and behaviors. This reveals the potential utility of using invasive fish populations to inform conservation practices in native ranges, and how pheromone research could further enhance fish conservation and monitoring. [ABSTRACT FROM AUTHOR]

This paper presents the first phase in the development and validation of a simple and reliable environmental (e) DNA method using conventional PCR to detect four species of non-native freshwater fish: pumpkinseed Lepomis gibbosus, sunbleak Leucaspius delineatus, fathead minnow Pimephales promelas and topmouth gudgeon Pseudorasbora parva. The efficacy of the approach was demonstrated in indoor tank (44 l) trials in which all four species were detected within 24 h. Validation was through two field trials, in which L. gibbosus was detected 6-12 h after its introduction into outdoor experimental ponds and P. parva was successfully detected in disused fish rearing ponds where the species was known to exist. Thus, the filtration of small (30 ml) volumes of pond water was sufficient to capture fish eDNA and the approach emphasised the importance of taking multiple water samples of sufficient spatial coverage for detecting species of random or patchy distribution. [ABSTRACT FROM AUTHOR]

The article focuses on a study conducted for a requirement of conservation monitoring of population and habitat utilization of sea lamprey Petromyzon marinus fishes in chalk streams of Great Britain. Topics include population decline of fishes due to river fragmentation and habitat loss, utilisation of spawning habitats, migration of fish species, observation of water temperature, nest counting in chalk streams and rivers and assessment methodologies for protection of spawning habitats.

The European Non‐native Species in Aquaculture Risk Analysis Scheme (ENSARS) was developed in response to European ‘Council Regulation No. 708/2007 of 11 June 2007 concerning use of alien and locally absent species in aquaculture’ to provide protocols for identifying and evaluating the potential risks of using non‐native species in aquaculture. ENSARS is modular in structure and adapted from non‐native species risk assessment schemes developed by the European and Mediterranean Plant Protection Organisation and for the UK. Seven of the eight ENSARS modules contain protocols for evaluating the risks of escape, introduction to and establishment in open waters, of any non‐native aquatic organism being used (or associated with those used) in aquaculture, that is, transport pathways, rearing facilities, infectious agents, and the potential organism, ecosystem and socio‐economic impacts. A concluding module is designed to summarise the risks and consider management options. During the assessments, each question requires the assessor to provide a response and confidence ranking for that response based on expert opinion. Each module can also be used individually, and each requires a specific form of expertise. Therefore, a multidisciplinary assessment team is recommended for its completion. [ABSTRACT FROM AUTHOR]

Developed for carrying out risk assessments under the European Commission (EC) Council Regulation No 708/2007 concerning the use of alien and locally absent species in aquaculture (ASR), the European Non‐native Species in Aquaculture Risk Assessment Scheme (ENSARS) is briefly summarised, and the ‘Organism’ module is applied to the 24 species listed in ASR's Annex IV. Four other ENSARS modules (Infectious Agent, Facility, Pathway, and Socio‐economic) were used to assess two case study species (European catfish Silurus glanis L. and red swamp crayfish Procambarus clarkii Girard). No Annex IV species was categorised as low risk, 10 as moderately low risk, 12 as medium risk, two as moderately high risk and none as high risk. The results are discussed and recommendations are made on further development of the scheme as well as the need to have multiple assessors of multidisciplinary expertise from the Member States concerned carry out the assessments using an approach similar to that carried out by EU Reference Laboratory proficiency tests. [ABSTRACT FROM AUTHOR]

The consequences of fractional spawning on the early-life growth rates of invasive goldfish (Carassius auratus) from the Qinghai-Tibet Plateau were studied using the otolith microstructure of samples collected in June 2011. The effect of the estimated hatching date on the subsequent growth of individual fish was determined by back-calculating their number of growth days, daily growth rates and the onset of their second growth season. The number of growth days in the first growth season ranged from 93 to 186 days. Following hatching, daily growth rates increased rapidly to a maximum of 0.55 mm days -1 before declining to 0.09 mm days -1. The effect of the duration of the first growth season on individuals was significant (P < 0.01), with later spawned fish having faster growth rates. These later spawned fish were, however, still significantly smaller in body length at the end of the first growth season (37 ± 4 mm in late hatched fish vs 55 ± 9 mm in early hatched fish). However, the smaller, later hatched fish started growing earlier in their second growth season than all other fish (P < 0.01) and subsequently achieved larger growth increments (P < 0.01), suggesting that the larger, early-hatched fish were investing more resources in gonadal growth than somatic growth in their second growth year. Thus, this invasive population revealed considerable plasticity in their early-life growth rates that were associated with the hatching date, potentially having substantial effects on their development in their second year of life. [ABSTRACT FROM AUTHOR]

Lake Naivasha is a shallow, freshwater lake in the eastern Rift Valley of Kenya. Its fish community now comprises only introduced species. Oreochromis spirulus niger was stocked in 1925 as a forage fish for the largemouth bass, Micropterus salmoides, introduced in 1929 for sport fishing. Further introductions of tilapiines followed for commercial exploitation. A gillnet fishery opened in 1959, and the annual species catch composition to 2000 was dominated by Oreochromis leucostictus. Following their accidental introduction, carp Cyprinus carpio appeared in catches in 2002; by 2010, it comprised >99% of landings by weight. Carp now provides a sustainable fishery in a lake heavily impacted by anthropogenic stressors, including water abstraction and nutrient enrichment. Oreochromis niloticus was reintroduced in 2011 to reinvigorate tilapia stocks following the collapse of its stocks in the 1990s and early 2000s, and the African catfish Clarias gariepinus is now captured in small but increasing numbers. The current status of the fishery, especially the predominance of carp, presents major management challenges; these are addressed by stakeholder engagement and co-management. The introductions have artificially created a commercial fishery that provides substantial societal benefits in a semi-arid region of a developing country with high poverty levels. [ABSTRACT FROM AUTHOR]

The utility of using fish scales collected during stock assessment exercises to assess the trophic relationships of riverine fishes using their stable isotopes of d13C and d15N was tested using three riverine fish communities in England (Rivers Great Ouse, Ivel and Goyt). In each river, European barbel Barbus barbus was an important species, with other cyprinid species, including chub Squalius cephalus, present. Stable isotope analyses was completed using relatively small sample sizes per species (<11) from fish samples collected in 2001, 2005 and 2006 when up to 5 scales were collected from each fish. The calculation of standard ellipse areas (as a measure of trophic niche size) revealed that relative to other fishes, B. barbus occupied high trophic positions with minimal overlap in their trophic niche with other species, especially S. cephalus. As the analysed fish samples comprised species of various length ranges and as length has strong ontogenetic consequences for fish diet composition, generalized linear models were developed in which length was the covariate; model outputs included length-adjusted mean δ13C and δ15N for each species. In each fish community, significant differences in δ13C and δ15N were apparent between B. barbus and S. cephalus, but were less apparent between B. barbus and other fishes. Thus, whilst the utility of using fish scales from stock assessments in stable isotope analyses are limited due to the differing length ranges of the sampled fishes, they can be useful in identifying trophic differences between species when methods such as stomach content analyses are unavailable. [ABSTRACT FROM AUTHOR]

Summary: Here the length–weight relationships (LWR, hereafter) of Pareiorhina pelicicei, Trichomycterus candidus, T. pirabitira, and T. piratymbara are provided. Samples of each species were collected between April and July 2017 with a hand net (1.5 mm mesh) in three sites from the upper Paraná River basin, Southeastern Brazil. These results increase knowledge about the LWR of Neotropical freshwater fish. [ABSTRACT FROM AUTHOR]

The article offers information on a study which assesses and chracterize the Pterygoplichthys ambrosttii catfish in lower Paranapanema River in Brazil. It states that samples for the study were gathered from February 2010 to October 2011 and that sieves, cast nets and trawl were used for sample collection. Results reveal that fish sex ratios of the species varies through life cycle, growth act and mortality.

The effects of number of fish that are aged and scale sub-sampling strategies on the precision of estimates of mean age-length increments from populations of Rutilus rutilus, Leuciscus leuciscus and Leuciscus cephalus were tested. Analyses used data derived from river fish communities in eastern England, U.K.. Regarding the number of fishes analysed in each age group, for each species and mean fork-length increment at age, significant relationships were detected between sample size ( n) and the coefficient of variation of the mean ( Z) and mean length increment [ABSTRACT FROM AUTHOR]

The changes in the fish assemblage of the Capivara Reservoir, Brazil, were assessed over a 20 year period. Of 50 native fishes present in the initial samples, 27 were no longer present in the final samples, but there had been an addition of 11 invasive fishes, suggesting the occurrence of substantial shifts in fish diversity and abundance. [ABSTRACT FROM AUTHOR]

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Non-native fishes are frequently used to enhance aquaculture and fisheries; if introduced into the wider environment, then the majority will have negligible effects on native biodiversity. However, a minority will become invasive, causing adverse ecological effects, and so management actions may be needed to minimize their dispersal and impacts. These actions include eradication attempts from specific waters or well-defined spatial areas, population control by suppression (e.g. through removal programmes) and containment of existing populations to prevent their further spread. These remedial actions have generally only been undertaken across large spatial areas in developed countries; experience suggests a fundamental constraint is a lack of selective removal methods that target the non-native fish species only. For example, eradication methods tend to be limited to low technology, 'scorched-earth' techniques (e.g. biocide chemicals) whose use is generally constrained to relatively small and enclosed water bodies. Risk management of non-native fishes should ensure that actions taken are commensurate with the level of risk posed by that species in the environment; although pre-introduction risk assessment schemes have been developed, there remains a lack of decision support tools for post-introduction situations. Although this inhibits the management of non-native fishes in the environment, control programmes such as those against common carp Cyprinus carpio in Australia and topmouth gudgeon Pseudorasbora parva in England and Wales suggest there is potential for invasions to be managed and controlled within large spatial areas, even if their eradication may not be feasible. [ABSTRACT FROM AUTHOR]

Britton JR, Cucherousset J, Grey J, Gozlan RE. Determining the strength of exploitative competition from an introduced fish: roles of density, biomass and body size. Ecology of Freshwater Fish 2011: 20: 74-79. © 2010 John Wiley & Sons A/S As species introductions can result in increased resource competition for coexisting species in the receiving ecosystems, the effects of increased exploitative competition for limited food resources from an introduced fish ( Pseudorasbora parva) on a coexisting fish ( Cyprinus carpio) were tested experimentally using a substitutive-additive design. Additive treatments revealed that the growth of C. carpio was significantly suppressed following the introduction of P. parva with the magnitude of growth suppression directly proportional to P. parva density and biomass. A substitutive treatment that tested for the effect of intraspecific competition revealed that when C. carpio were introduced at a similar biomass to P. parva, there was no significant difference in the extent of the suppressed growth. At the same density, however, the effect of C. carpio (higher biomass) on growth was significantly above that of P. parva (lower biomass). This was independent of the initial body sizes of the introduced fishes. Thus, the interspecific competition imposed by P. parva was only as strong as the intraspecific competition of C. carpio when present at a similar biomass. [ABSTRACT FROM AUTHOR]

Hatchery-reared and wild roach Rutilus rutilus were correctly classified to their rearing environment in a discriminant function using data on their scale circuli patterns. The discriminant function was then used to classify recaptured R. rutilus by their origin (hatchery-reared and wild) during a riverine stocking evaluation. At 8 and 18 months post-stocking, 10 and 7% of fish captured in the vicinity of the stocking site were classified as hatchery-reared. [ABSTRACT FROM AUTHOR]

Britton JR, Harper DM, Oyugi DO. Is the fast growth of an equatorial Micropterus salmoides population explained by high water temperature? Ecology of Freshwater Fish 2010: 19: 228–238. © 2010 John Wiley & Sons A/S Marginal increment analysis of scales collected from the introduced Micropterus salmoides population of Lake Naivasha, Kenya revealed the formation of an annual growth check, validating their use to age individual fish. Subsequent analysis of scales from 372 fish collected between 2002 and 2009 revealed individuals were very fast growing compared with native populations in North America and other introduced populations in Europe, South America, Africa and Asia. This was likely to be as a result of the water temperatures in Lake Naivasha exceeding 20 °C throughout the year. This was corroborated by a meta-analysis of the growth parameters asymptotic length L∞ and growth coefficient K from across their geographical range that revealed variance was explained by differences in mean annual air temperatures. At a break point of approximately 10 °C, there was a shift to reduced L∞ and increased K, suggesting a temperature driven trade-off between growth rate and ultimate length. When adjusted for temperature and weighted for sample size, there were significant differences between the growth parameters of the North American and introduced populations, suggesting that other abiotic and biotic variables were also important determinants of the growth of individuals between the two ranges. [ABSTRACT FROM AUTHOR]

1. Temperate regions with fish communities dominated by cold-water species (physiological optima <20 °C) are vulnerable to the effects of warming temperatures caused by climate change, including displacement by non-native cool-water (physiological optima 20–28 °C) and warm-water fishes (physiological optima >28 °C) that are able to establish and invade as the thermal constraints on the expression of their life history traits diminish. 2. England and Wales is a temperate region into which at least 38 freshwater fishes have been introduced, although 14 of these are no longer present. Of the remaining 24 species, some have persisted but failed to establish, some have established populations without becoming invasive and some have become invasive. The aim of the study was to predict the responses of these 24 non-native fishes to the warming temperatures of England and Wales predicted under climate change in 2050. 3. The predictive use of climate-matching models and an air and water temperature regression model suggested that there are six non-native fishes currently persistent but not established in England and Wales whose establishment and subsequent invasion would benefit substantially from the predicted warming temperatures. These included the common carp Cyprinus carpio and European catfish Silurus glanis, fishes that also exert a relatively high propagule pressure through stocking to support angling and whose spatial distribution is currently increasing significantly, including in open systems. 4. The potential ecological impacts of the combined effects of warming temperatures, current spatial distribution and propagule pressure on the establishment and invasion of C.  carpio and S.  glanis were assessed. The ecological consequences of C.  carpio invasion were assessed as potentially severe in England and Wales, with impacts likely to relate to habitat destruction, macrophyte loss and increased water turbidity. However, evidence of ecological impacts of S.  glanis elsewhere in their introduced range was less clear and so their potential impacts in England and Wales remain uncertain. [ABSTRACT FROM AUTHOR]