The commercial push net fisheries for glass eels in France and its handling mortality

Glass eels, the young life stage of the endangered European eel entering the European continental waters, are exploited for human consumption (direct, or on-grown) and restocking. Restocking is considered as a potential contribution to the conservation of the stock. For this, the mortality of glass eels during capture should be low. We studied the handling mortality of glass eels obtained by commercial push net fisheries in different rivers in France in 2019 and 2020. The direct mortality of glass eels in 41 fishing trips of 29 boats varied from zero to 3.1% (mean 0.3%). Skin lesions identified by staining occurred in 31% (range: 4%–98%) of the eels. Post fishing mortality of glass eels varied from zero to 67.2%. The mean total fishing mortality was with 7.4% (range 0%–56.2%), considerably lower than in previous studies. The Sustainable Eel Group (SEG) issues certificates to fishers applying best practices for a responsible fishery. Comparing certified to uncertified fishers, the certified fishers have on average significant lower lesions and post-fishing mortality rates, However, some uncertified fishers have an equal or better glass eel quality than certified fishers. Noting that certified fishers score better on average, and avoid the worst scores, we conclude that the SEG-certification scheme for responsible fishing is effective

The Sound of Batteries: An Operando Acoustic Emission Study of the LiNiO2_{2} Cathode in Li–Ion Cells

The development of advanced Li‐ion batteries relies on the implementation of high‐capacity Ni‐rich layered oxide cathode materials, such as NCM and NCA, among others. However, fast performance decay because of intrinsic chemical and structural instabilities hampers their practical application. Hence, thoroughly understanding degradation processes is crucial to overcome current limitations. To monitor instabilities of electrode materials under realistic operating conditions, the application of nondestructive operando techniques is required. While structural changes of crystalline phases can be studied by X‐ray diffraction, microstructural changes (e. g., particle fracture) cannot be easily accessed in situ and are therefore mostly investigated ex situ. Here, we use acoustic emission (AE) measurements to probe a potential next‐generation cathode material in real‐time. Specifically, we focus on LiNiO$_{2}$(LNO) and demonstrate that AE events in different frequency ranges can be correlated with the formation of the cathode solid‐electrolyte interphase and the mechanical degradation during electrochemical cycling

Fish community composition in small lakes: The impact of lake genesis and fisheries management

Gravel pit lakes are common across Europe. These novel ecosystems serve as model systems to study human‐induced and natural colonisation of isolated lakes by fish. Fisheries‐management activities can quickly spread species over large distances, possibly homogenising fish communities across ecosystems, while fostering local fish diversity. Our objective was to evaluate the effects of lake genesis (gravel pit lakes < 100 years old vs. natural lakes of glacial genesis ~10,000 years old) and fisheries management (fish stocking activities present vs. absent) on the fish community in small lakes, while controlling for key environmental variables known to affect lake fish communities. We sampled fish communities by electrofishing and multimesh gillnetting in 47 isolated lakes managed for fisheries, and 19 unmanaged and isolated lakes of both natural and artificial origin in northern Germany. Unmanaged lakes were used as reference to assess fisheries‐management impacts in small natural and artificial lakes. We caught 178,506 fish from 30 species and found that the accumulation of native lake fish species in lakes was associated with fisheries management, which increased local species richness (α‐diversity) and number of predatory species, and reduced among‐lake variation in fish community composition (β‐diversity; i.e., homogenisation). The homogenisation‐effect associated with fisheries happened with introduced native fish species, whereas non‐native species were rarely detected. In unmanaged gravel pit lakes, the littoral fish community composition was substantially different to the communities present in both types of managed lakes and unmanaged natural lakes. Therefore, the relatively young unmanaged gravel pit lakes revealed evidence of ongoing, stochastic colonisation processes that resulted in comparatively species‐poor fish communities. We concluded that fisheries management by anglers speeds up the colonisation of gravel pit lakes with native fish species in the study area. For planning initial fish introductions in newly created gravel pit lakes, it is recommended that fish communities from ecologically similar natural lakes within the same geographical region are used as references to maintain the biotic integrity of newly created fish communities.This work was jointly supported by the German Federal Ministry of Education and Research (BMBF) and the German Federal Agency for Nature Conservation (BfN) with funds granted by the German Federal Ministry for the Environment, Nature Conservation and Nuclear Safety (BMU; grant number: 16LC1320A).Peer Reviewe

Length–weight relations for 19 freshwater fish species (Actinopterygii) from the lowland Elbe River, Germany

Monthly and mean length–weight relations (LWRs) were calculated for 19 freshwater fish species from the middle section of the lowland Elbe River (Germany): Abramis brama (Linnaeus, 1758); Alburnus alburnus (Linnaeus, 1758); Anguilla anguilla (Linnaeus, 1758); Ballerus ballerus (Linnaeus, 1758); Blicca bjoerkna (Linnaeus, 1758); Cobitis taenia Linnaeus, 1758; Esox lucius Linnaeus, 1758; Gobio gobio (Linnaeus, 1758); Gymnocephalus cernua (Linnaeus, 1758); Leuciscus aspius (Linnaeus, 1758); Leuciscus idus (Linnaeus, 1758); Leuciscus leuciscus (Linnaeus, 1758); Lota lota (Linnaeus, 1758); Perca fluviatilis Linnaeus, 1758; Romanogobio albipinnatus (Lukasch, 1933); Rutilus rutilus (Linnaeus, 1758); Sander lucioperca (Linnaeus, 1758); Scardinius erythrophthalmus (Linnaeus, 1758); and Squalius cephalus (Linnaeus, 1758). The values of the exponent b in the LWR W = aTLb ranged from 2.882 (Lota lota) to 3.517 (Cobitis taenia) and the correlation coefficient (r2) was greater than 0.96 for all species except for Cobitis taenia with 0.93. The relations allow for the accurate estimation of weight from length data with reduced handling times of fish in the field while enabling comparisons with other regions and future studies. The calculated LWRs together with species-specific abundance and catch data will be useful for fisheries modeling and estimating population status and related fish species protection, especially for the endangered species in the Elbe River

Electrochemical properties of micro-batteries with single NCM-111 secondary particles as cathode

Although lithium ion batteries (LIB) are already used in numerous applications, e.g. as power source in portable devices, the optimization of the battery performance, such as life-time, cyclability and energy density, is of large interest for using LIBs in e.g. electrical vehicles or temporary storage systems for renewable energy sources. Typically, the performance of the cathode active material is investigated using composite electrodes. Advanced composite electrodes consist of a complex architecture with comparably large secondary particles (10 µm - 30 µm) of the active material built up from nanometer sized primary particles. Furthermore, they also contain additives influencing the electrochemical properties of the composite electrode. To avoid such influences and to further optimize the performance of the cathode’s active material a detailed understanding of the impact of the cathode architecture on the ionic and electronic transport processes is necessary. Please click Additional Files below to see the full abstract

Design-of-experiments-guided optimization of slurry-cast cathodes for solid-state batteries

Laboratory research into bulk-type solid-state batteries (SSBs) has been focused predominantly on powder-based, pelletized cells and has been sufficient to evaluate fundamental limitations and tailor the constituents to some degree. However, to improve experimental reliability and for commercial implementation of this technology, competitive slurry-cast electrodes are required. Here, we report on the application of an approach guided by design of experiments (DoE) to evaluate the influence of the type/content of polymer binder and conductive carbon additive on the cyclability and processability of Li$_{1+x}$(Ni$_{0.6}$Co$_{0.2}$Mn$_{0.2}$)$_{1}$−xO$_{2}$ (NCM622) cathodes in SSB cells using lithium thiophosphate solid electrolytes. The predictions are verified by charge-discharge and impedance spectroscopy measurements. Furthermore, structural changes and gas evolution are monitored via X-ray diffraction and differential electrochemical mass spectrometry, respectively, in an attempt to rationalize and support the DoE results. In summary, the optimized combination of polymer binder and conductive carbon additive leads to high electrochemical performance and good processability