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Kenzo Kaifu - One of the best experts on this subject based on the ideXlab platform.

  • Challenges in assessments of Japanese Eel stock
    Marine Policy, 2019
    Co-Authors: Kenzo Kaifu
    Abstract:

    Abstract Although Japanese Eel, Anguilla japonica, is one of the most important fish species in East Asia, only one study has assessed Japanese Eel stocks to date. That study estimated the stock status and dynamics of this species mainly based on Japanese fishery data on recruiting glass Eel, growing-phase yellow Eel, and maturing silver Eel. That study also used data on biological characteristics, such as the growth, maturity and natural mortality of both Japanese Eel and European Eel, A. anguilla , to develop an age- and sex-structured production model. However, Japanese fishery statistics for glass Eel are not an appropriate data source for stock assessment because there are non-negligible illegal and unreported glass Eel catches occur in Japan. Moreover, yellow and silver Eel fishery data in Japan are biased by those pertaining to stocked individuals, although most of the data are for Eels originating from Japan as opposed to other countries and regions within the species distribution range. In addition to these problems in data collection, the biological parameters might be biased by contamination from stocked individuals. Therefore, it is difficult to assess the stock status of Japanese Eels using an age- and sex-structured production model based on official Japanese Eel fisheries statistics. The legality and traceability of glass Eel fisheries and Eel trading should be improved to enable appropriate stock assessment in future, and data on catch per unit effort (CPUE) in areas where Eel stocking is not conducted should be collected throughout the species distribution range.

B. Knights - One of the best experts on this subject based on the ideXlab platform.

  • On the application of models of European Eel (Anguilla anguilla) production and escapement to the development of Eel Management Plans: the River Severn
    ICES Journal of Marine Science, 2007
    Co-Authors: M. W. Aprahamian, Alan Walker, B. Williams, A. Bark, B. Knights
    Abstract:

    Aprahamian, M. W., Walker, A. M., Williams, B., Bark, A., and Knights, B. 2007. On the application of models of European Eel (Anguilla anguilla) production and escapement to the development of Eel Management Plans: the River Severn. - ICES Journal of Marine Science, 64: 1472-1482.The European Eel stock has declined significantly since the 1980s, and the Eel Recovery Plan of the European Commission requires Member States to develop river basin Eel Management Plans (EMPs) that will achieve an escapement of silver Eels that equals or exceeds 40% of the escapement biomass that would be produced in the absence of human activities. However, because silver Eel escapement is not quantified within the UK, a modelling approach is required to estimate potential and actual escapement, and to assess the likely effects of management measures. We focus on two approaches developed in the UK, the Reference Condition Model (RCM) and the Scenario-based Model for Eel Populations (SMEP), and illustrate how such approaches can be used in EMPs using selected data from the River Severn. The RCM results indicate that the yellow Eel population in the River Severn basin may be just 30-40% of the potential density indicated by reference conditions derived from a selection of rivers between the late 1970s and the early 1980s. The challenges of applying a model designed to be as realistic of Eel production as possible, and the limited data on natural Eel habitat and Eel production in the Severn, preclude a SMEP analysis similar to that of the RCM, but simulations based on a simplified basin description and Eel survey data from the early 1980s illustrate the potential of this model to assess compliance and test management scenarios.

Tetsuya Hirano - One of the best experts on this subject based on the ideXlab platform.

  • Development of a homologous radioimmunoassay for Eel prolactin.
    General and comparative endocrinology, 1991
    Co-Authors: Reiko Suzuki, Tetsuya Hirano
    Abstract:

    Abstract A highly specific and homologous radioimmunoassay (RIA) for the measurement of prolactin (PRL) in the plasma and the pituitary of the Eel was developed using a rabbit antiserum to Eel PRL. PRL was purified from the pituitary of Japanese Eel ( Anguilla japonica ). Pituitary extracts and plasma from the Japanese and European Eels exhibited displacement curves parallel to the Eel PRL standard. Plasma and pituitary extracts from chum salmon, rainbow trout, Japanese charr, tilapia, goldfish, and carp, as well as plasma from hypophysectomized Eel, showed negligible cross-reactivity. PRL and growth hormone (GH) preparations from chum salmon, tilapia, and sheep, carp PRL, and Eel GH did not cross-react with the antibody. The RIA sensitivity was less than 0.1 ng Eel PRL per milliliter. Intra- and interassay coefficients of variations were 2.4 and 11.8%, respectively. The immunoreactive PRL levels in plasma and pituitary of the Eel adapted to 50% seawater were significantly lower than those of the Eel in fresh water. Plasma PRL levels increased maximally 2 days after transfer from seawater to fresh water, as would be expected from the well-established role of PRL in freshwater adaptation in several euryhaline teleosts.

Cédric Briand - One of the best experts on this subject based on the ideXlab platform.

  • Eel density analysis (EDA 2.2.1). Escapement of silver Eels (Anguilla anguilla) from French rivers
    2018
    Co-Authors: Cédric Briand, Pierre-marie Chapon, Laurent Beaulaton, Hilaire Drouineau, Patrick Lambert
    Abstract:

    EDA (Eel Density Analysis) is a modelling tool which allows the prediction of yellow Eel densities and silver Eel escapement from electrofishing survey networks. The 2018 version of EDA (2.2.1) is based on a dataset of 29 183 electrofishing operations compared to 24 541 for 2015 (version 2.2.0) and only 9 556 in the 2012 version (2.1). The larger dataset is explained by the inclusion of deep water electrofishing operations and the Eel specific surveys. The model distinguishes from its 2012 (2.1) version by the prediction of Eel abundance per size class, separated with boundaries 150, 300, 450, 600 and 750 mm. The model estimates the Eel biomass on the French territory at 1.724 ± (1.242, 2.27) millions of silver Eels in 2015. Anthropogenic impacts corresponding to the glass Eel fisheries, amateur and commercial yellow Eel fisheries, silver Eel fisheries and turbine mortalities, will be included in the model to produce stock indicators Bcurrent, Bbest mandatory for the 2018 postevaluation of the Eel management plan.

  • A review of glass Eel migratory behaviour, sampling techniques and abundance estimates in estuaries: implications for assessing recruitment, local production and exploitation
    Reviews in Fish Biology and Fisheries, 2014
    Co-Authors: Andrew J. Harrison, Cédric Briand, Alan M. Walker, Adrian C. Pinder, Miran W. Aprahamian
    Abstract:

    Recruitment of the three northern hemisphere Eel species (European Eel Anguilla anguilla , American Eel Anguilla rostrata and Japanese Eel Anguilla japonica ) has reduced significantly over the past thirty-five years. The stock of the European Eel is described as being outside safe biological limits, with urgent action required by European Union Member States to assist recovery of the panmictic stock. Stock recruitment models and estimates of silver Eel output from a river catchment are strongly influenced by the degree of certainty in estimating key population parameters of each life history stage. Therefore, management decisions aimed at enhancing Eel populations rely on sound scientific evidence, based upon a fundamental understanding of the complex anguillid Eel life cycle. This review paper focuses on the estuarine entry phase of the Eel life cycle and synthesises the current scientific knowledge with regard to glass Eel migratory behaviour, sampling methods and abundance estimates within estuaries. Although the behavioural and environmental processes modulating glass Eel migration patterns are reasonably well understood, site specific factors play a significant role in determining fine scale distribution patterns at an individual estuary level. Given the large resource commitment required to adequately sample this key life history stage, behavioural studies of migration patterns on a local scale are crucially important to aid the design of robust sampling programmes aimed at quantifying seasonal abundance and annual recruitment.

Christopher H.k. Cheng - One of the best experts on this subject based on the ideXlab platform.

  • Presence of prolactin receptors in Eel liver and carp kidney and growth hormone receptors in Eel liver
    Comparative biochemistry and physiology. A Comparative physiology, 1991
    Co-Authors: T.y. Hui, Christopher H.k. Cheng
    Abstract:

    Abstract 1. 1. 125 I-labelled ovine prolactin and bovine growth hormone were used to test for the presence of prolactin and growth hormone receptors in membrane prepared from tissues of the white Eel Anguilla japonica , the carp Ctenopharynogodon idellus and the ricefield Eel Monopterus albus . 2. 2. High levels of specific 125 I-labelled ovine prolactin binding were found in white Eel liver membranes and carp kidney membranes. 3. 3. High levels of specific 125 I-labelled bovine growth hormone binding were detected in white Eel liver membranes. 4. 4. Tissues of the ricefield Eel did not bind 125 I-labelled ovine prolactin or bovine growth hormone. 5. 5. The results suggest the presence of prolactin receptors in white Eel liver and carp kidney membranes and growth hormone receptors in white Eel liver membranes.