Evaluation of observer‐ and industry‐based catch data in a recreational charter fishery

There is international recognition for greater inclusion of recreational fisheries catch data in species, fisheries and ecosystem assessments. Recreational charter fisheries provide important social services and contribute to total species catches. This study compares and validates industry logbook catch and effort data (1,357 trips) against observer data (154 trips) across six ports in a recreational charter fishery in eastern Australia. The mean numbers of clients and fishing effort (hours) per trip varied inconsistently between data sources and among ports. Logbooks did not adequately report released catches, and the mean number of species retained per trip was consistently underestimated in logbooks compared to observer data. For both data sources, catch rates of total individuals and key species displayed similar trends across different units of effort; catch per hour, client, client/hour and trip. The mean catch rates of total individuals and most key species, except those retained for bait, were similar across data sources, as were estimates of total fleet harvests. The length compositions of retained catches of some key species displayed truncation of larger organisms in the observer data whereas other species did not. Despite the shortcomings of the logbook data, future fishery and species monitoring strategies could include industry and observer data sources.     

Applications and characteristics of angler diary programmes in Ontario, Canada

Angler diary programmes ( n =46, 1979–1997) implemented in Ontario by the Ontario Ministry of Natural Resources are reviewed, and the different uses of angler diary programmes, levels of participation and differences in programme design are reported. In Ontario, angler diary use is common, but successful application is limited. This review revealed a variety of uses and approaches for administering angler diary programmes. Problems arise when programmes are initiated without the complete commitment of the administrators and agency, or when there is no regular review so adaptive changes can be made. If administrators realize the potential biases and problems associated with diaries, and design programmes to control them, angler diaries can provide favorable cost-effective results. With reduced funding and staffing constraints, angler diary programmes could become the primary method of data collection for specialized and remote fisheries.     

Landings, logbooks and observer surveys: improving the protocols for sampling commercial fisheries

The sampling of commercial marine fisheries for management purposes often displays a key weakness in the form of poor documentation of the scientific basis of sampling and estimation, the assumptions made, and the practical constraints. This paper reviews systematically the theoretical and practical options that can remedy this situation and recommends that decisions be archived in regularly updated ‘Sampling Approach and Modifications’ (SAM) documents. Defining the target population, the observable population (usually a subset of the target), and the assumed links between them is important, along with the distinction between design‐ and model‐based sampling approaches. Fleet‐targeted and stock‐targeted sampling strategies are contrasted, the latter being much harder to implement. Sampling protocols aimed at estimating quantities of fish landed and discarded, length–frequency distributions, length‐related variables such as age, weight and maturity, and ratio variables such as catch per unit of effort and the proportions of discards are discussed, together with the raising of estimates to fleet and/or stock levels. The ideas are summarized in the specific contexts of landings sampling, logbook schemes and sea‐going observer surveys. SAMs are commended for enhancing the scientific value of fishery sampling, and for encouraging methodological discussions among users and producers of the data.     

基于渔捞日志的海阳近海渔业资源种类组成及生物多样性分析

根据2013年在山东海阳近海海域生产的15艘渔船的渔捞日志,初步分析了该海域渔业资源的种类组成及生物多样性特征。全年共捕获渔业资源种类25种,隶属于14目、21科、25属,鱼类有16种,以暖温种和暖水种为主,虾蟹类4种,头足类2种,水母类2种,多毛类1种。优势种类主要为黄鮟鱇(Lophius litulon)、蓝点马鲛(Scomberomorus niphonius)及口虾蛄(Oratosquilla oratoria)、海蜇(Rhopilema esculentum)、三疣梭子蟹(Portunus trituberculatus)、日本蟳(Charybdis japonica)、中国明对虾(Fenneropenaeus chinensis)等。其中,口虾蛄为全年优势种。渔业资源群落多样性指数和丰富度指数春季最高,秋季次之,夏季最低,通过与山东近海历史调查数据对比可知,该海域渔业资源量大幅下降;均匀度指数(0.13~0.73)变化较小;海阳近海春季和秋季种属组成相似性较高。本研究可为海阳近海渔业资源管理和修复提供参考依据。