Fish Recovery Research Articles

Connectivity shapes delivery of multiple ecological benefits from restoration

Connectivity and landscape context are common considerations in the spatial prioritisation of conservation actions. Similar spatial principles can also be used to inform the selection, prioritisation and monitoring of sites for restoration, but it is not clear whether these variables consistently shape the delivery of benefits from restoration. This study aimed to determine whether, and how, seascape connectivity and landscape context combine to influence the recovery of fish and crustacean communities at a restoring coastal wetland. We measured changes to biodiversity (fish species richness), fisheries benefits (fisheries harvested abundance) and functioning (fish functional diversity) bi-annually at a 200 ha restoring wetland, and three control sites, in eastern Australia between 2017 and 2021. Connectivity and landscape context were quantified using a combination of in-field measurements, remote sensing techniques and least-cost path analysis. Biodiversity, fisheries benefits, and functional diversity increased at the restoration site over time, but these metrics did not change significantly at any of the control sites over the same time period. The delivery of each of the three co-benefits at the restoration site was also positively linked to increased wetland connectivity, larger areas of mangroves and higher salinity levels in the recovering seascape. These results support tighter integration of connectivity and landscape context to optimise and inform spatial planning in restoration, and we suggest that this is essential for supporting the delivery of multiple benefits from recovering habitats and seascapes. Adopting similar approaches to understand the drivers of restoration success would improve the ecological and economic outcomes of actions.

Using a time-dynamic food web model to compare predation and fishing mortality in Pleuroncodes monodon (Galatheidae: Crustaceae) and other benthic and demersal resource species off central Chile

The stock biomass of the carrot prawn (Pleuroncodes monodon) in the south-central area of Chile (33º–39°S) has decreased progressively in the last 12 years. The depletion and lack of recovery of carrot prawn and other fish and crustacean stocks has been attributed mostly to fishing mortality (F). Predation can be also an important factor for the dynamics of marine species, especially those that are important prey in the ecosystem, like the carrot prawn and other demersal crustaceans. However, predation mortality (M2) has been less studied and quantified in Chile and elsewhere. Therefore, it is important to estimate and compare predation (M2) and fishing (F) mortality to understand their individual and combined effects on the dynamics of fishing stocks. In this study, we analyzed the biomass changes of carrot prawn and other components of the marine food web in south-central Chile from 1992 to 2018. For this, we built a food web model that was later fit to time series of observed biomass and catch data, using observed fishing mortality as forcing factor. We used the Ecopath with Ecosim software as modeling platform. This model provided M2 and F series for carrot prawn and other demersal crustaceans, which were compared to evaluate their relative contribution to total mortality (Z) from 1992 to 2018. The quantitative model considered 29 functional groups, from primary producers to top predators, and the following fishing fleets operating in the study area: artisanal and industrial purse seine fleets, artisanal and industrial hake trawling fleet and demersal prawn trawling fleet. The results indicated that M2 was the main component of Z in adults and juveniles carrot prawns, with Chilean hake as the main predator in both cases. M2 was responsible for 84 % and 86 % of Z of adults and juveniles of carrot prawns, respectively. M2 was also greater than F in yellow prawns (Cervimunida johni), whose main predator was big eye flounder (Hippoglossina macrops). In contrast, F was greater than M2 for the nylon shrimp (Heterocarpus reedi). We conclude that the stock dynamics of the carrot and yellow prawns has been strongly influenced in recent decades by the predation by Chilean hake on pre-recruits of carrot prawn as prey and bigeye flounder on yellow prawn as prey. We recommend that M2 should be considered both in evaluating the past dynamics of these stocks used to establish their status and in future projections used to establish biologically acceptable catch.

Comparison of feeding preferences of herbivorous fishes and the sea urchin Diadema antillarum in Little Cayman.

On Caribbean coral reefs, losses of two key groups of grazers, herbivorous fishes and Diadema antillarum, coincided with dramatic increases in macroalgae, which have contributed to decreases in the resilience of these coral reefs and continued low coral cover. In some locations, herbivorous reef fishes and D. antillarum populations have begun to recover, and reductions in macroalgal cover and abundance have followed. Harder to determine, and perhaps more important, are the combined grazing effects of herbivorous fishes and D. antillarum on the structure of macroalgal communities. Surprisingly few studies have examined the feeding preferences of D. antillarum for different macroalgal species, and there have been even fewer comparative studies between these different herbivore types. Accordingly, a series of in-situ and ex-situ feeding assays involving herbivorous fishes and D. antillarum were used to examine feeding preferences. Ten macrophytes representing palatable and chemically and/or structurally defended species were used in these assays, including nine macroalgae, and one seagrass. All species were eaten by at least one of the herbivores tested, although consumption varied greatly. All herbivores consumed significant portions of two red algae species while avoiding Halimeda tuna, which has both chemical and structural defenses. Herbivorous fishes mostly avoided chemically defended species while D. antillarum consumed less of the structurally defended algae. These results suggest complementarity and redundancy in feeding by these different types of herbivores indicating the most effective macroalgal control and subsequent restoration of degraded coral reefs may depend on the recovery of both herbivorous fishes and D. antillarum.

Balloon Tag Manufacturing Technique for Sensor Fish and Live Fish Recovery.

Fish may experience injuries and mortality when they pass through hydraulic conveyances at hydropower dams, even if these conveyances are designed to be fish-friendly, such as downstream bypass systems, modified spillwaysand turbines. The main methods used to study fish passage conditions in hydraulic structures involve direct, in situ testing using Sensor Fish technology and live fish. Sensor Fish data helps identify physical stressors and their locations in the fish passage environment, while live fish are assessed for injuries and mortality. Balloon tags, which are self-inflating balloons attached externally to Sensor Fish and live fish, aid in their recovery after passing through hydraulic structures. This article focuses on the development of balloon tags with varying numbers of dissolvable, vegetable-based capsules containing a mixture of oxalic acid, sodium bicarbonate powders, and water at two different temperatures. Our research determined that balloon tags with three capsules, injected with 5 mL of water at 18.3 °C, consistently achieved the desired balloon volume. These tags had a mean inflation volume of 114 cm3 with a standard deviation of 1.2 cm3. Among the balloon tags injected with water at 18.3 °C, it was observed that the two-capsule balloon tags took the longest time to reach full inflation. In addition, the four-capsule balloon tags demonstrated a faster inflation start time, while the three-capsule balloon tags demonstrated a faster deflation start time. Overall, this approach proves to be effective for validating the performance of new technologies, improving turbine design, and making operational decisions to enhance fish passage conditions. It serves as a valuable tool for research and field evaluations, aiding in the refinement of both the design and operation of hydraulic structures.

Selected Research and Dramatic Surgery Fish Cases of Incisive Complete in Fish Surgical

Abstract
 Health problems which can be treated exclusively by surgical means are relatively uncommon in fish. Fish surgery feat is vital essential and inevitable for the at fish diseases treatment and fish recovery. Consequently, only a limited number of procedures have been developed and reported in the literature. Despite use of analogous surgical instruments and surgical techniques to those employed in other animals, fish are a very diverse taxon and specific anatomy and physiology should be reviewed before surgical procedures are performed. Surgical planning often requires advanced diagnostics such as ultrasonography and imaging. Essantial surgical procedures include cutaneous and intracoelomic mass excision, ophthalmic procedures, reproductive surgery, brain surgery, visceral organs surgery, gastrointestinal foreign body removal, visceral organs examples, and buoyancy concerns. This article reviews several surgical procedures that have been performed in fish and highlight various aspects of surgical care which relate specifically to fishes. In this review article, administration of sedation and anesthesia, anaesthetic agents, pain in fish, obtrusive fish cases surgery, fish cases surgery operations examples, frequently used anesthetics and preoperative considerations, underwater surgery, out of water surgery, specific surgery procedures, microsurgery techniques, laparoscopy, catheter implantation and laparotomy were discussed for fish researchers. Suggestions for appropriate postoperative management are also discussed.

Manifestation of Heat-Induced Valuable Dietary Nucleotide Salvage in Food Prepared from Aged Fish in Fast Protein and Metabolites Liquid Chromatography, ATP-Bioluminescence Assay, and NMR Spectra

Dietary nucleotides and nucleosides, primarily inosine monophosphate (IMP) and the adenine nucleotide pool (ANP), are widely considered as essential nutrients responsible for multiple biological functions. Food prepared from meat and fish is the main source of these substances in the human diet, and it is extremely important to implement storage and processing techniques ensuring their maximum preservation and even accumulation during maturation or conditioning. In experiments with freshly refrigerated grass carp and defrosted Alaska pollock fillets it was discovered, initially using Fast Protein and Metabolites Liquid Chromatography and the ATP-bioluminescence test, and afterwards validated by NMR spectroscopy, that heat treatment identical to conventional culinary processing in aqueous or wet media at temperatures above 62 °C leads to nucleotide salvage (recovery) in aged fish. A significant increase in the concentration of IMP, and even an emergence of ANP substances, were reliably demonstrated in fish samples which had already partially or fully lost these components during prolonged storage due to the ATP breakdown metabolic reactions. Owing to this recovery, the nutritive value of ready-to-eat food can be higher than was initially evaluated in raw products before heat treatment: an effect that should certainly be considered in practical nutrition. Moreover, it is necessary to reconsider the widely acknowledged system of indices of freshness based on nucleotides and nucleosides elaborated a long time ago for raw meat and fish products.

Utilization of Natural Honey on Wound Healing in African Catfish Clarias gariepinus (Burchell, 1822) (Siluriformes: Clariidae)

In Nigeria, the African catfish, Clarias gariepinus is one of the most widely cultivated fish species. It can be injured by cannibalism, high stocking density, or other means. If these injuries are not treated properly, the wounds could operate as a precursor to additional pathogen infection, causing stress, health problems, and loss of fish stocks. As a result, the ability of honey to cure wounds in African catfish was explored. Honey was added to a 40% crude protein meal at different inclusion levels of 0.0, 100, 150 and 200ml/kg diet. The lateral area (1 cm) of the fish model was lacerated after which the fish were fed varied quantities of honey-infused diets for 14 days. During this time weight gain and wound healing rate of the fish were monitored and measured. Results showed that fish fed diet containing 200ml/kg honey gained the most body weight (9.7g+3.60), while those fed the 0ml/kg honey diet recorded the least weight (5.1g+6.11). Fish fed low honey levels (0.00 and 100.00 ml/kg diet) required longer time to recover from their wounds completely, but those on a 200ml/kg honey diet recovered completely within the 14-day experimental period. From the results of this research, it is suggested that honey be included in fish diet at the rate of 200ml/kg of diet to accelerate wound healing and invariably boost fish recovery after injuries.

Lights at the end of the tunnel: The incidence and characteristics of recovery for Australian threatened animals

Recovery of threatened species is a widely recognised conservation goal. We assess the incidence and characteristics of recovery for threatened Australian animals from the establishment of Australia's national environmental legislation in 2000 to 2022. Formal de-listings have been few, and mostly not indicative of actual recovery. However, we assessed that 29 taxa (1 fish, 4 frogs, 1 reptile, 8 birds and 15 mammals), representing 6.5 % of the 446 species that we consider were justifiably listed as threatened, have recovered over this period such that they no longer meet the eligibility criteria for listing as threatened.Most of the recovered species are mammals whose previous decline was due to introduced predators. Their recovery has been enabled by sustained management actions (establishment of predator-free havens, translocations and predator control). The lack of recovery of invertebrates is possibly because these have received little conservation investment. The limited recovery of fish is due to limited capacity for abating the threats of introduced fish predators and of exploitation and degradation of aquatic systems. Species threatened by habitat loss and degradation, fire and climate change are under-represented in recoveries.De-listing of the taxa that we assess here to have recovered would provide a tangible recognition and indicator of conservation success and help maintain the integrity of the threatened species list. However, most of the recovered species would rapidly become eligible for re-listing should their conservation management be withdrawn. Although there is a prevalent trend for decline of Australia's threatened species, these recoveries merit recognition.

Occurrence and characterisation of Eustrongylides species in Australian native birds and fish

In Australia, nematodes belonging to the genus Eustrongylides were believed to be endemic species until the late 20th century when they were all considered to be E. excisus, invalid or inquirendae. Although these nematodes have frequently been reported in Australian fish, reptiles, and birds and cause disease or mortality among them, there has been no attempt to date to characterise them genetically. Globally, also, no one has validated or defined suitable genetic markers to distinguish between species of Eustrongylides. In this study, adult Eustrongylides from little black cormorant (Phalacrocorax sulcirostris; n = 3) and larvae from mountain galaxias (Galaxias olidus, n = 2) and a Murray cod (Maccullochella peelii, n = 1), and a Murray cod-trout cod hybrids (Maccullochella peelii x Maccullochella macquariensis, n = 1) were available for morphological examination and molecular characterisation. The adult nematodes from cormorants were identified as E. excisus. Sequences of the 18S and ITS regions were then obtained for all nematodes, which were identical among all specimens (larvae and adults) and also identical to those of E. excisus available in the GenBank. However, only one base pair difference exists between the 18S sequences of E. excisus and E. ignotus, with limited sequences available in GenBank accompanied with proper morphological data for the nematodes. With that limitation in mind, identifying our specimens as E. excisus suggests spill-over – that it is an introduced parasite species that has successfully established its life cycle among Australian native species – may have occurred. Our study is the first report of E. excisus in the little black cormorant, P. sulcirostris. Our results do not exclude the possibility of the occurrence of other species of Eustrongylides, either native or exotic, in Australia. This parasite is zoonotic and with increasing demand for fish and changing dietary preferences, such as the consumption of raw or undercooked fish, its occurrence in the flesh of the fish is concerning. This parasite is also associated with anthropogenic habitat alteration affecting the reproductive success of the infected hosts. Therefore, awareness among the relevant authorities of the presence of the parasite in Australia and its adverse impact on native animals is crucial for the success of conservation plans such as fish recovery and relocation efforts.

Recovery or continued resuscitation? A clinical diagnosis of Colorado River sub-basin recovery programs

With a particular emphasis on the Upper Colorado River Endangered Fish Recovery Program (UCR-EFRP) and Lower Colorado River Multi-Species Conservation Program (LCR-MSCP), we analyze, for each program, four system properties that contribute to resilience: system architecture, which includes (1) connectivity and distribution and (2) assemblage of system elements; and system dynamics, which includes (3) social and natural capital flows and (4) system renewal and continuation. Each of these system properties is analyzed based on specific social and corresponding biophysical indicators. The system properties were ranked on a carefully constructed scale based on gradations of each system property (derived from the literature) on both social and biophysical indicator standing. Our results indicate that the UCR-EFRP has relatively better social architecture and dynamics with relatively less impact on the ecological architecture and dynamics compared to the LCR-MSCP, though this result may be a function of the greater amount of infrastructural constriction and path dependence in the lower basin compared to the upper basin. We conclude by suggesting that a transformative pathway forward needs greater adaptability and flexibility incorporated into the social architecture and dynamics to move toward better ecological health of the river.

Long-term exposure to azoxystrobin induces immunodeficiency in fish that are vulnerable to subsequent rhabdovirus infection

Azoxystrobin (AZ) is one of the most widely used strobilurin fungicides in the world, and its residue has seriously endangered aquatic ecological security. Our previous data showed that AZ exposure may reduce the resistance of fish to rhabdovirus infection in aquatic environment. Here, we further reported a potential long-term adverse effect of AZ exposure on the antiviral and immunosuppressive recovery in fish, and observed that mitochondrial dynamic balance was disturbed by AZ in which excessive mitochondrial fission occurred in response to decreased ATP levels. When a recovery operation was performed in AZ-exposed cells and fish, infectivity of our model virus, spring viraemia of carp virus (SVCV), was significantly decreased in vitro (using the epithelioma papulosum cyprini [EPC] fish cell line) and in vivo (using zebrafish) in a time-dependent manner. Also, the expression of eight innate antiviral immune genes (IFNs, ISG15, MX1, RIG-I, IRF3, Nrf2 and HO-1) showed a similar change to SVCV replication between the longer exposure period and the expression recovery. Additionally, AZ facilitated horizontal transmission of SVCV in a static cohabitation challenge model, predicting the increase of the potential for the viral outbreak. Therefore, our data suggest that long-term effect of AZ on irreparable impairment in fish made AZ residue potentially greater for ecological risks.

Examining the diversity, stability and functioning of marine fish communities across a latitudinal gradient

AbstractAimAs anthropogenic stressors on the biosphere intensify, understanding how communities respond to disturbances is critical. Biodiversity is often thought to promote the stability of communities over time and enhance ecosystem functioning. However, results have been inconsistent, and the multifaceted linkages among diversity, stability and functioning under acute disturbances remain poorly understood. We experimentally tested the responses of marine fish communities to disturbance (i.e., acute habitat loss) across a diversity gradient spanning 35 degrees of latitude in the western Atlantic Ocean to assess the diversity–stability relationship and the interplay between diversity, stability, and fish biomass recovery (as a proxy for function) in marine fish communities.LocationWestern Atlantic Ocean [Maine, Massachusetts, North Carolina, Florida (USA), Belize and Panama].Time period2016–2017.Major taxa studiedSmall, bottom‐dwelling (‘cryptobenthic’) fishes.MethodsWe experimentally tested the response of marine fish communities to disturbance across a diversity gradient on human‐made dock pilings. We holistically sampled cryptobenthic fish communities, then we imposed a severe disturbance by removing all benthic epifauna. We then compared the community stability, defined as the constancy in community composition, on disturbed and undisturbed pilings after one year.ResultsDiversity showed a negative effect on community stability at both the regional (across docks) and local (within docks) scales. Similarly, local diversity was negatively correlated with ecosystem function. These effects are exacerbated by the habitat loss imposed via our experimental treatment.Main conclusionsOur results suggest that habitat loss may re‐shuffle diverse, tropical communities more intensively than species‐poor, temperate communities, which impacts biomass recovery, our proxy of functioning. Contrary to ecological theory, in small‐bodied, benthos‐associated vertebrate communities, biodiversity may neither promote stability nor functioning, suggesting that human disturbances may be particularly impactful in tropical, high‐diversity ecosystems.

Benefits of stocking fewer but larger individuals with implications for native fish recovery

Artificial propagation is commonly used to reduce extinction risk for native, imperiled fish species. Thus, identifying stocking strategies that most effectively augment adult abundance is a critical aspect of successful adaptive management. The threatened June sucker ( Chasmistes liorus) , endemic to Utah Lake, UT, USA, experienced major declines in abundance following extensive ecosystem degredation. Over 800 000 June sucker were stocked from hatcheries, grow-out ponds, and refuge populations from 1990–2019 across a range of sizes and seasons. Here, we evaluated post-stocking survival of June sucker using a Cormack–Jolly–Seber model with three covariates: size at stocking, origin, and season. Survival was positively correlated with size at stocking, with evidence of a possible size-selective predation threshold between 200 and 300 mm, and spring stocking appeared to produce higher survival rates than summer or fall. We also compared cost and benefit for stocking hatchery-origin June sucker at different sizes, finding that stocking fewer but larger (age-2) individuals was more cost-effective than stocking more but smaller (age-1) individuals. Our results highlight operational changes that can help maximize the efficacy of native fish hatchery programs.

Marine Resource Recovery Following the COVID-19 Event in Southern Thailand

This study investigated coral and reef fish recovery following the COVID-19 event between low and high environmental disturbance reefs at Racha Yai Island, Southern Thailand. Three and four 50-m permanent line transects were set at low and high environmental reefs to collect the percent of live coral cover, fish diversity and abundance, and fish trophic-functional groups based on diet and habitat use. Our results showed a significant rise in the percentage of live coral cover, the number of individual fish, the number of fish species, and species richness at both bays following the COVID-19 lockdown due to a crucial reduction in human activities on the reef. In addition, there were increases in the number of corallivore fishes belonging to Chaetodontidae and Pomacentridae families and a reduction of omnivorous fish at the fish-feeding tourist attraction reefs due during the COVID-19 lockdown due to reducing fish-feeding tourism. This indicated that restricted human activities and reduced anthropogenic stress on a coral reef may have substantial short-term impacts on reef fish diversity. Our insights could help designate guidelines to manage tourist impacts on coral reefs and aid in their prolonged persistence. Doi: 10.28991/CEJ-2022-08-11-011 Full Text: PDF

Influence of the method of preparation of clove oil emulsion on the anaesthetic effect in fish (on the example of Clarias gariepinus

In aquaculture, the use of clove oil as a natural anaesthetic for hydrobiontes is gaining popularity. There are several ways to prepare an aqueous emulsion for anaesthesia, which creates a problem for technologists in choosing the most effective one. The purpose of the study was to compare the anaesthetic effect of clove oil in three methods of preparation of the mixture on the youth of the African clary catfish. The study was conducted at the Centre for Aquatic Bioresources and Aquaculture of the National University of Life and Environmental Sciences of Ukraine. Research methods – Ichthyological and statistical. The activity of a water-based clove oil preparation was evaluated using three methods: hot, cold, and alcohol. Experimental material – juvenile fish of the clary catfish with an individual body weight from 22 to 285 g. Experimental conditions: the experimental material was kept without feeding for a day before the start of the study; fish anaesthesia was performed in the water at the temperature of +26 0C; the duration of manipulations with each fish was minimal. The effectiveness of various methods of preparation of the emulsion was evaluated by the duration of fish entry into the state of anaesthesia and withdrawal from this state. The advantage of the hot method of preparing an aqueous emulsion of clove oil over the other two is established: the duration of fish entry into anaesthesia was 22% shorter compared with the cold method, and 12.3% – with the alcohol method (p ≤ 0.05). The duration of fish recovery from anaesthesia with the hot method of preparation of the mixture was also shorter: compared to the cold method – 18% (p ≤ 0.05), with the alcohol method – 43.2% (p ≤ 0.001). Using correlation analysis, a relationship was established between the duration of fish entry into the state of anaesthesia and the individual body weight of the fish. Degree of binding: high for hot (r = 0.606) and alcohol methods (r = 0.529) and medium for a cold method of preparation of an anaesthetic mixture (r = 0.385). The results obtained are of practical value for improving the method of anaesthesia of fish using clove oil

Conservation and restoration of riverine spawning habitats require fine-scale functional connectivity and functional heterogeneity

A severe extinction crisis of migratory fish caused by extensive hydropower development and climate change has attracted widespread environmental concern. Conserving and restoring riverine spawning habitat for migratory species is advantageous for population recovery. Depending on the reproductive characteristics of fish with adhesive eggs, functionally heterogeneous spawning habitats are required to support different stages of reproductive activity. However, few aquatic assessment models are available to consider the fine-scale functional connectivity between heterogeneous spawning habitats. This study developed a function-based framework that linked fine-scale functional connectivity modeling to habitat quality evaluations for the population recovery of migratory fish. The function path tree (FPT) model within the framework could identified the spatiotemporal dynamics of fine-scale connectivity patterns by emphasizing the attribute-dependence of patch arrangements. Here, we used the Chinese sturgeon, a well-known endangered anadromous fish producing adhesive eggs in the Yangtze River, as an example to demonstrate the applicability of the framework. Additionally, the ecological effectiveness of river restorations to overcome the detrimental influence of climate change on discharge decrease was also investigated. Compared to prior research, our methodology effectively enhanced the predictive performance of spatiotemporal distributions and quality assessments of spawning habitats. A strong correlation was discovered between the ecological profit indicator (HQI) and the estimated fecundity (R2 = 0.941) and field-collected eggs (R2 = 0.918). The minimum spawning discharge decreased from 8400 m3/s to 7000 m3/s by substrate restoration, with the optimal HQI growth rate of 52.7 % at Q < 8400 m3/s. This work will optimize long-term conservation for imperiled migratory species and help develop strategies to build resilience to ongoing environmental changes in flow-reduced rivers.

Freshwater Fish Biodiversity in a Large Mediterranean Basin (Guadalquivir River, S Spain): Patterns, Threats, Status and Conservation

The Guadalquivir River Basin is one of the largest in the Iberian Peninsula and has a remarkable freshwater biodiversity. Although many studies on hydrological regimes or water quality have been conducted in this basin the biodiversity of freshwater fish, as well as their distribution and conservation status, has never been globally addressed as in other Iberian basins. In this context, we synthesized information on freshwater fish using field procedures and a bibliographic search. Fish distribution patterns at different spatial scales and general environmental conditions were analyzed as well as the conservation status of the fish community. We documented the presence of 40 species (20 native and 20 exotic) in the basin during the 20th century until today. However, we only captured 18 species during the field sampling, with a prevalence for any native species of less than 23% (except Luciobarbus sclateri). The highest species richness was found in mid reaches, while the lower reaches had very low diversity values. Around 50% of species are threatened; according to the IUCN, several species are declining at an alarming rate and others are probably extinct and/or their current status is unknown. Human disturbances during the last few decades have caused serious changes in fish distribution and consequently to their conservation status. Hydrological alterations, intensive agriculture and introduced species are probably the principal reasons for Guadalquivir’s ichthyofauna imperilment. Our study indicates an urgent and real need to identify important areas for fish conservation to guarantee a minimum fish biodiversity conservation over the long term, as well as effective strategies for fish recovery where it still is possible.

Post-release locomotor activity of ice-angled Northern Pike

The study of the stress response and subsequent recovery of angled fish can inform the development of best practices for catch-and-release (C&R) angling. While large bodies of research exist detailing the impacts of C&R during warm periods of the year (i.e., open water), relatively few studies have been conducted during the colder months when sub-freezing temperatures are prominent, and anglers are targeting fish through the ice. Most research on ice angling has focused on conventional physiological stress indicators (i.e., blood cortisol, lactate, glucose) with comparatively little known about potential post-release behavioral impairments. To that end, we evaluated the consequences that ice angling C&R has on the post-release locomotor activity of Northern Pike (Esox lucius). Over 7 days of ice-angling, 20 Northern Pike were captured, air exposed for 0, 2, or 5 min and then harnessed with a biologger (tri- axial accelerometer) prior to release. The post-release locomotor activity of the Northern Pike was then recorded for 30 min before the biologger was retrieved using a quick release system. It was determined that while overall locomotor activity decreased over time during the post-release monitoring period, there was no difference between air exposure treatment groups in locomotor activity. These data reveal that Northern Pike exhibit similar locomotor activity whether they are air exposed in winter for 0, 2, or 5 min. Nonetheless, there may still be further long-term stresses that were not measured within the time frame of this experiment. Therefore, we recommend anglers fish in a way that minimizes air exposure and as a result reduces the potential for sublethal impairments or mortality.

Life and death in a dynamic environment: Invasive trout, floods, and intraspecific drivers of translocated populations.

Understanding the relative strengths of intrinsic and extrinsic factors regulating populations is a long‐standing focus of ecology and critical to advancing conservation programs for imperiled species. Conservation could benefit from an increased understanding of factors influencing vital rates (somatic growth, recruitment, survival) in small, translocated populations, which is lacking owing to difficulties in long‐term monitoring of rare species. Translocations, here defined as the transfer of wild‐captured individuals from source populations to new habitats, are widely used for species conservation, but outcomes are often minimally monitored, and translocations that are monitored often fail. To improve our understanding of how translocated populations respond to environmental variation, we developed and tested hypotheses related to intrinsic (density dependent) and extrinsic (introduced rainbow trout Oncorhynchus mykiss, stream flow and temperature regime) causes of vital rate variation in endangered humpback chub (Gila cypha) populations translocated to Colorado River tributaries in the Grand Canyon (GC), USA. Using biannual recapture data from translocated populations over 10 years, we tested hypotheses related to seasonal somatic growth, and recruitment and population growth rates with linear mixed‐effects models and temporal symmetry mark–recapture models. We combined data from recaptures and resights of dispersed fish (both physical captures and continuously recorded antenna detections) from throughout GC to test survival hypotheses, while accounting for site fidelity, using joint live‐recapture/live‐resight models. While recruitment only occurred in one site, which also drove population growth (relative to survival), evidence supported hypotheses related to density dependence in growth, survival, and recruitment, and somatic growth and recruitment were further limited by introduced trout. Mixed‐effects models explained between 67% and 86% of the variation in somatic growth, which showed increased growth rates with greater flood‐pulse frequency during monsoon season. Monthly survival was 0.56–0.99 and 0.80–0.99 in the two populations, with lower survival during periods of higher intraspecific abundance and low flood frequency. Our results suggest translocations can contribute toward the recovery of large‐river fishes, but continued suppression of invasive fishes to enhance recruitment may be required to ensure population resilience. Furthermore, we demonstrate the importance of flooding to population demographics in food‐depauperate, dynamic, invaded systems.

Assessing Conservation Potential of Streams for Spikedace and Loach Minnow Using Species Distribution Modeling

Abstract Identifying, evaluating, and prioritizing freshwater systems for conservation is a persistent challenge for managers tasked with conservation and recovery of native fishes. We used historical records from the Gila River basin, the national hydrography data set, and Random Forest modeling to predict probability of Spikedace Meda fulgida and Loach Minnow Rhinichthys cobitis occurrence throughout their range in the Gila River basin. Models for both species performed moderately well, with relatively high predicted probability of occurrence at streams with historical records. Predicted probability of occurrence was also relatively high in several streams without historical records of focal species, suggesting that there are unoccupied reaches throughout the Gila River basin with similar environmental conditions to historically occupied reaches for both species. Unoccupied reaches with the highest predicted probability of occurrence may have a greater chance of supporting translocated populations of focal species. Our results can be used as a first step for locating reaches most likely to support translocated populations of Spikedace and Loach Minnow within their respective historical ranges. Our approach may be applicable to other species of conservation concern with available historic records in need of population restoration.