Catch-release Research Articles

Better boundaries: identifying the upper extent of fish distributions in forested streams using eDNA and electrofishing

AbstractThe management of species that occur in low densities is a conservation concern worldwide across taxa with consequences for managers and policymakers. The distribution boundary at the upper extent of fish in North America receives extra attention because stream reaches with fish are managed differently and often have more protections than fishless reaches. Here, we examine the relative reliability of water environmental DNA (eDNA), polymerase chain reaction (PCR)‐amplified for Coastal Cutthroat Trout (Oncorhynchus clarkii clarkii) to detect the upper extent of fish across streams as a potential management tool compared to standard electrofishing methods. We provide estimates of fish detection probabilities from eDNA analyses, and probabilities of detection for both eDNA field samples and quantitative PCR (qPCR) given covariates of habitat characteristics and fish densities from electrofishing. We present a primer and probe based on the cytochrome oxidase I gene using qPCR to detect trout DNA across water samples from 60 forested streams in the Pacific Northwest, USA using high‐resolution spatial sampling. In 28% of streams, the upper extent of fish matches between methods. In over half of the streams, Coastal Cutthroat Trout eDNA was detected above the electrofishing last‐fish boundary. Although some detections could be attributed to false‐positive errors, eDNA results extend the upstream, leading edge of fish by 50–250 m from the electrofishing boundary. In 20% of the streams, detections of last‐fish occurred higher in the stream network with electrofishing rather than eDNA, but generally by only 50 m. Modeled results revealed that the occurrence of trout eDNA was higher in wider‐stream locations and that eDNA detections occurred at lower electrofishing densities (<5 trout per 50 linear m). We also showed that three replicate eDNA samples were sufficient to capture trout eDNA when eDNA was present. Although eDNA constitutes an effective addition to approaches to delimit the upper extent of fish, its effectiveness depends on previous knowledge of the last‐fish boundary to apprise where to start sampling and targeting fish species anticipated to be last‐fish. We present evidence that eDNA is a valuable tool in investigating fish distributions taking its place alongside traditional high‐effort catch–release tools.

Estimating purse seine volume during capture: implications for fish densities and survival of released unwanted catches

Abstract High fish densities negatively impact catch welfare and the survival of unwanted catches released from purse seines. To avoid overcrowding fish before being released, regulations have been implemented in the Northeast Atlantic mackerel and herring fisheries that limit the proportion of the seine that can be retrieved before catches are released. However, it is yet unknown how seine volume, and thus fish density, relates to proportion of seine retrieved. In this study, we have estimated the in-water volume of purse seines used in the Norwegian mackerel and herring fisheries as a function of proportion seine hauled and seine size. Purse seine geometry was monitored with multibeam sonar at sea and a log-linear mixed effects model was applied to the estimated seine volumes. The results indicate a 33-fold decrease in contained volume from 10 to 80% seine hauled and a threefold difference in volume between the largest and smallest measured seines. Fish densities in the seine were predicted to vary greatly depending on seine and catch size and under some conditions exceed safe crowding levels before the catch release limit is reached. This study questions the rationale of having the same catch release limit for all seine and catch sizes.

Effects of brown trout ( Salmo trutta L.) stocking and catch‐release practice on angling catches in the River South Rena in southeast Norway

Preserving of fish species and populations is important whether it is for exploitation or just for conservation. Management of fisheries aim to maintain fishable stocks that are attractive to anglers, and different means are performed. In this study from the River South Rena in southeastern Norway, conducted during 1991–2005, the effects of supportive stocking of hatchery reared brown trout (Salmo trutta L.) from 1996, and bag limit (BL) and catch‐release (CR) practice for the target species brown trout, from 2002, were explored. Effects of supplemental brown trout stocking was not noticeable, except from one year following a year of exceptional high number of stocked fish, actually 41% of the catches, whereas in the following years this proportion remained constant about 10%, and the catches remained high in 2003 and 2004, mainly due to increased angling success rate after BL‐CR introduction.

Catch-Release System for Dosing and Recycling Silver(I) Catalyst with Status of Catalytic Activity Reported by Fluorescence.

The silver(I) catch-release system composed of nanoswitch 1 and the anthracene-appended crown ether 2 is infallibly driven by chemical triggers and ion transfer. Any state of the silver(I) translocation is self-reported by a ratiometric emission signature at 472 and 554 nm. In the self-sorted networked state I, the silver(I) ions are tightly shielded inside nanoswitch [Ag(1)]+ ("catch") so that their catalytic activity is zero while emission at 554 nm is maximum. Addition of zinc(II) releases silver(I) from [Ag(1)]+ and generates the catalytically active and fluorescent complex [Ag(2)]+. In this networked state II ("release") both catalytic activity and emission at 472 nm are maximum. Removal of the original trigger regeneratesnetworked state I. ON/OFF control and recycling of catalyst was demonstrated over three in situ cycles.

Enantioselective Redox-Neutral Coupling of Aldehydes and Alkenes by an Iron-Catalyzed "Catch-Release" Tethering Approach.

The reductive coupling of aldehydes and alkenes is an emerging technology that holds the potential to reinvent carbonyl addition chemistry. However, existing enantioselective methods are limited to form “branched” products. Herein, we present a directed enantio- and diastereoselective alkylation of aldehydes with simple olefins to selectively yield linear coupling products. This is achieved by redox-neutral remote functionalization, whereby a tethering “catch–release” strategy decisively solves the key problems of reactivity and selectivity.

Leveraging a "Catch-Release" Logic Gate Process for the Synthesis and Nonchromatographic Purification of Thioether- or Amine-Bridged Macrocyclic Peptides.

Macrocyclic peptides containing N-alkylated amino acids have emerged as a promising therapeutic modality, capable of modulating protein-protein interactions and an intracellular delivery of hydrophilic payloads. While multichannel automated solid-phase peptide synthesis (SPPS) is a practical approach for peptide synthesis, the requirement for slow and inefficient chromatographic purification of the product peptides is a significant limitation to exploring these novel compounds. Herein, we invent a "catch-release" strategy for the nonchromatographic purification of macrocyclic peptides. A traceless catch process is enabled by the invention of a dual-functionalized N-terminal acetate analogue, which serves as a handle for capture onto a purification resin and as a leaving group for macrocyclization. Displacement by a C-terminal nucleophilic side chain thus releases the desired macrocycle from the purification resin. By design, this catch/release process is a logic test for the presence of the key components required for cyclization, thus removing impurities which lack the required functionality, such as common classes of peptide impurities, including hydrolysis fragments and truncated sequences. The method was shown to be highly effective with three libraries of macrocyclic peptides, containing macrocycles of 5-20 amino acids, with either thioether- or amine-based macrocyclic linkages; in this latter class, the reported method represents an enabling technology. In all cases, the catch-release protocol afforded significant enrichment of the target peptides purity, in many cases completely obviating the need for chromatography. Importantly, we have adapted this process for automation on a standard multichannel peptide synthesizer, achieving an efficient and completely integrated synthesis and purification platform for the preparation of these important molecules.

Cancer catch and sugar release cue immune attack

Glycocalyx-modifying antibody-enzyme conjugates increase antibody-dependent cell-mediated cytotoxicity against HER2-positive breast cancer cells.

A catch–release catalysis system based on supramolecular host–guest interactions

An adamantane adorned Pd(ii) catalyst interacts with β-cyclodextrin moieties on iron oxide magnetic nanoparticles to give a catch–release catalysis system.

Evaluating recreational fisheries for an endangered species: a case study of taimen, Hucho taimen, in Mongolia

Understanding the tradeoff between exploitation and conservation is difficult in data-poor situations, which are typical for most recreational fisheries, even in developed countries. In a developing country where the target species is endangered, the stakes are higher and the management resources are fewer. We combined a mark–recapture experiment, life history invariants, and meta-analysis to parameterize a delay-difference model for a population of the endangered giant Eurasian trout (taimen, Hucho taimen ) in northern Mongolia. The model allowed us to evaluate the impacts of a recreational fishery for taimen based on a suite of population characteristics including equilibrium abundance, biomass, and mean weight. The Bayesian framework and Monte Carlo simulations combine disparate sources of information while keeping track of uncertainty as it propagates through the model. In the case of taimen in the Eg–Uur watershed, the existing catch–release recreational fishery has likely reduced taimen abundance, biomass, and mean weight by less than 10% compared with levels predicted in the absence of recreational fishing. In comparison, if all taimen caught in this fishery were retained (as they are elsewhere in Mongolia), there is a 57% chance that such harvest levels, if maintained, would lead to the eventual extirpation of the population.

Effect of Number of Marked Fish and Years of Repetition on Precision in Studies of Contribution to a Fishery

Methods are developed for predicting the expected precision for studies of the contribution of fish to a fishery, based upon the number of fish marked and the number of years an experiment is repeated. Studies concerned with estimating catch–release ratios, comparing catch–release ratios, and comparing distributions of catch are considered. It is suggested that releases of marked fish should be repeated for at least three or four broods, and often there is little advantage in releasing more than 50 000 marked fish per release group. Although we explicitly address studies of contribution to ocean fisheries, the methods apply directly to a broad range of studies involving marked fish, from evaluations of harvest rates on catchable-trout plants to estimates of catch–escapement ratios for Pacific salmon.Key words: precision, experimental design, number of fish to mark, number of years to release marked fish, catch–release ratios, distribution of catch