Assessing the global distribution of river fisheries harvest: a systematic map protocol
© The Author(s) 2017
Received: 24 May 2017
Accepted: 26 October 2017
Published: 4 December 2017
Although surface freshwater comprises < 0.01% of the total water volume of earth, freshwater inland capture fisheries and aquaculture represent 40% of the global reported finfish harvest. While the social, economic, and ecological importance of inland fish and fisheries is difficult to overstate, they are often undervalued and underappreciated. Accurate information about these highly dispersed fisheries is inherently difficult to acquire, often unreported, and not collected in a standardized format globally. A standardized river fishery database is needed for managing aquatic systems as well as for defining relevant development policies. Here, we describe our methodology to search, identify, and describe available river fisheries information to create a harmonized global database of river fisheries harvest. This database will provide the first global database of spatially and temporally explicit river fisheries data. The database can be used to identify locations, hotspots of data collection, and gaps in existing knowledge and will be especially important to inform studies and management at larger spatial scales (i.e., watershed, regional, or global scales). This database will also be critical for developing fish biomass models for rivers, which can provide managers with information critical for decision-making, such as improved valuation methods for river fish and fisheries.
This systematic map protocol describes the methodology to search, identify, and describe available information on river fish and fisheries across the globe. We define river fisheries as “both capture and aquaculture of river finfish species for food, income, or recreation”. River fish species are those finfish that live part, or all of their lives in rivers. The searches will be conducted for the period from 1950 to present using bibliographic databases and grey literature sources. To identify relevant evidence, pre-defined inclusion and exclusion criteria will be used to screen articles at title, abstract, and full text. A searchable database containing extracted meta-data from relevant included studies will be developed and presented as a geodatabase. The final systematic map will consist of a descriptive narrative report of the distribution and content of river fish literature including a geodatabase of available information.
River fisheries, defined as both capture and aquaculture of river fish species for food, income, or recreation contribute substantially to meeting challenges faced by individuals, society, and the environment in a changing global landscape [1, 2]. For example, in the Lower Mekong Basin, 80% of the 60 million inhabitants directly rely upon the river fisheries for food and livelihoods . Additionally, with upwards of 1700 fish species, the Mekong River is a global ‘hotspot’ of fish biodiversity , so understanding the relationship between the human fisheries system and the natural ecological system is critical for maintaining both the biodiversity of the resident fishes and well-being of the local human communities in the area. While the social, economic, and ecological importance of inland fish and fisheries is difficult to overstate, they are often undervalued and underappreciated . This is due to the fact that accurate information about these highly dispersed fisheries is inherently difficult to acquire, often unreported, and not collected in a standardized format globally [6, 7]. Consequently, these fisheries are often given low priority in planning and policy discussions relative to other uses of river ecosystem services such as drinking water, agriculture, or energy production [5, 8].
Data related to riverine fisheries are not collected in any standardized format globally  and thus the extent and distribution of these fisheries has never been adequately assessed in aggregate. Targeted analyses have been conducted on certain river systems such as the Mekong [10, 11], or regions such as Southeast Asia  but the approaches (e.g., consumption surveys, intensive field sampling) would not be feasible at a global scale due to the cost and effort involved . Most river fisheries are highly diffuse and small-scale in nature and in areas lacking necessary infrastructure for regular reporting, so the data collection that is occurring is generally not systematically distributed, but instead tend to be focused in the most developed countries . Understanding the catch trends and predictions of river fisheries harvests is critical for the future of stakeholders who depend on these systems for food and livelihoods, but these fisheries harvests have not yet been quantitatively assessed at the global level in the ways that marine fisheries have been [15, 16].
The proposed systematic map protocol will provide a database of river fish harvest and assessment of available data. This study will also provide the first spatially and temporally located systematic map of river fisheries data regarding what species are fished, how much fish are being fished, and how those fish are being removed from river systems (for a systematic review of marine fisheries, see Chassot et al. ). It will provide location information where available as well as an overview of the knowledge base, including hotspots of data collection and information gaps in our knowledge base and will be especially important to studies and management at larger spatial scales (i.e., watershed, regional, or global scales). This database will be useful for biodiversity conservation as well as research including improving valuation methods for river fish and fisheries to more accurately recognize the full breadth of provided services or for assessing the relative importance of river fisheries to human populations globally. These data are necessary to develop biomass models that can be used to predict how river fishery could change under different scenarios, particularly in the context of global change . In doing so, river fish and fisheries can be better incorporated into decision making to support sustainable river fish and freshwater management. As recently described for North American inland fisheries, inland waters often have multiple public uses and management goals may be overlapping, conflicting, or mutually dependent . Resolving these interactions depends on the availability of accurate data and models to predict current fishery production and forecasts given pending local, regional, and global changes.
Identification of the topic
The “Rome declaration: ten steps to responsible inland fisheries”  synthesized the results of the 2015 global conference on inland fisheries of nearly 250 scientists, policy makers, and members of the development community from more than 40 countries, into a list of ten key actions to help ensure sustainable inland fisheries. This declaration was emphatically endorsed by the member parties at the 2016 FAO committee on fisheries as a sign of growing recognition of the importance of inland freshwater fisheries in many countries. The first step in this list is to “improve the assessment of biological production” of inland fisheries. The work described in this protocol was identified as a principal need to address this critical knowledge gap and has been since refined by the research team. A companion study focused on inland lakes was conducted by other members who participated in the 2015 global conference . Ultimately, the goal of the conference and its outcomes is to improve the sustainability of freshwater aquatic resources and to bring greater awareness of the value and sustainability challenges of inland fisheries around the world .
Objective of the map
This project aims to identify, collate, and describe information on the geographical distribution of river fish harvest. Relevant information consists of fisheries-dependent and fisheries-independent data on river fish, including where and how river fish were captured. Data on river fisheries harvest will be identified and collected using the systematic mapping method described below.
River fisheries database (available at no cost online through a USGS portal).
Systematic map of the state of river fisheries information (submitted for publication in this journal).
These products will provide an important data resource for researchers, policy makers, and managers of river fisheries and will be used for assessing variation and trends in river fisheries or for modeling production and predicting changes due to factors such as climate or land–water use change. This information may also be used as a basis for future quantitative systematic review questions related to the map findings, such as modeling changes in harvest over time or impacts from different harvest methods.
What is the global distribution of river fisheries harvest?
Key elements of the primary review question
Fish populations within river systems
Capture of populations and communities of finfish for food, income, or recreation 
Any reported distinct information on fish harvest biomass. The targeted data include species, weight, time, location, or changes in fish biomass
Shatt el Araba
Search terms were developed using keywords from fisheries articles then tested against a list of relevant articles from an independent literature review provided by a colleague (Cowx, University of Hull, pers. comm.). Additional file 1 describes the preliminary search process and provides the original search terms used for scoping. The final list of search terms reflects the need to include river names to target relevant terms given the broad scope of the research question. In some cases, the initial searches returned millions of results via Google Scholar and this strategy is aiming for a more targeted, relevant database consisting of hundreds of files. Additional search terms from the original test set did not increase the number of relevant articles returned from the search and were thus eliminated; however, the search string may be modified during the full searches as necessary. Search terms used for each river are provided in Additional file 1 and will be included as part of final project metadata and supplemental information.
All searches will be conducted in web browsers with cookies and browser history disabled and in private settings (e.g., using “incognito mode” in ‘Google Chrome’) to reduce bias generated by user-specific returns.
Databases and search engines
Publication databases/search engines
Web of Science Core Collections
Proquest Aquatic Science Collection
China Knowledge Resource Integrated Database
Grey literature sites
A Rocha International
Caribbean Natural Resources Institute
Catholic Agency for Overseas Development (CAFOD)
Centre for Environment, Fisheries and Aquaculture Science
Centre for International Forestry Research (CIFOR)
Convention on Biological Diversity
Department for International Development (DFID), UK
European Commission Joint Research Centre
European Fisheries and Aquaculture Research Organisation
FAO Fisheries and Aquaculture Department
Freshwater Ecoregions of the World
Global Environment Facility
Global Freshwater Biodiversity Atlas
Intergovernmental Platform on Biodiversity and Ecosystem Services (IPBES)
International Collective in Support of Fishworkers
International Development Research Centre (IDRC)
International Institute for Environment and Development (IIED)
International Union for Conservation of Nature (IUCN)
Marine Resources Assessment Group
North American Native Fishes Association
The Nature Conservancy
Organisation for Economic Co-operation and Development (OECD)
Stockholm Environment Institute
United Nations Environment Programme
United Nations Environment Programme-World Conservation Monitoring Centre
United Nations Development Programme
United States Agency for International Development (USAID)
Wildlife Conservation Society (WCS)
World Resources Institute
Worldwide Wildlife Fund (WWF)
African Caribbean, and Pacific Group of States Fish II Programme
ADB, African Development Bank
Australia—Commonwealth Scientific and Industrial Research Organisation
Biodiversity Information System for Europe
Canada—Federal Science Library (Combines ECC, DFO, and WAVES databases)
Denmark—Denmark-Danish Centre for Environment and Energy
England—Centre for Environment, Fisheries and Aquaculture Science
Finland—Natural Resource Institute Finland
Finland—Finland’s environmental administration
Germany—Leibniz Institute of Freshwater Ecology and Inland Fisheries, IGB
India—Central Institute of Fisheries Technology
Lake Tanganyika Authority
Lake Victoria Basin Commission
Lake Victoria Fisheries Organization
Murray–Darling Basin Authority
Myanmar/Thailand/Laos/Vietnam-Mekong River Commission
Netherlands Institute of Ecology
Netherlands—Royal Netherlands Institute of Sea Research
Nile Basin Initiative
NDF, Nordic Development Fund
Norway—Norwegian Institute for Water Research (NIVA)
South African Council for Science and Industrial Research
Sweden—IVL Swedish Environmental Research Institute
Sweden—Swedish Agency for Marine and Water Management
USA—Great Lakes Fishery Commission
USA/Canada—US Fish and Wildlife Service
USA—National Marine Fisheries Service
The publication search engines and databases will be queried using the Boolean phrasing described below in the topic search categories. Web crawling software  will be used to query and collate data from the grey literature databases and regional/country organization sites. The first 100 returns from each grey literature site (Table 3) will be reviewed for inclusion. Google Scholar, Web of Science, and Scopus will be searched because of relatively little overlap between search results of the search engine and databases . The China Knowledge Resource Integrated Database (CNKI) and Baidu Scholar will be used to target rivers where data or research may be presented in Mandarin. Proquest Aquatic Science Collection will also be included to capture reports and grey literature that may not be available through our directed grey literature searches.
Search terms and languages
Search engines and databases will be searched using the following terms and Boolean phrasing (* denotes a wildcard character to include multiple word endings). The list of search phrases is available in Additional file 1.
Example phrase: (Congo OR Zaire) AND river* AND (fish* OR fisher* OR aquaculture)
Search terms by language
Estimating the comprehensiveness of the search
Our search strategy was designed to provide a broad scope of results regarding river fisheries data to be as comprehensive as possible. Primary studies will be targeted while review papers will be used to identify primary studies and data. All articles gathered, including review papers, will be included in the final reference database. We recognize that a large amount of data may be reported only through grey literature or stored on organizational sites. As such, our search strategy includes 37 grey literature databases and 30 regional or country sites (Table 3). Further sites may be added as revealed by the search results to be potentially relevant.
For the search engine (Table 3), an accumulation or discovery curve strategy will be used to assess the return on investment for continuing through search results. As each river constitutes a distinct search, this process will be conducted for each river search, within each distinct database. Because this process includes a unique search for each river in each database, duplicates of the same articles will be collected. These will be screened during the “Article screening and study inclusion criteria” described below, but also allow calculation of overlap between databases. The process is similar to that used for recording the cumulative number of species in a particular environment as a function of search effort . As new relevant articles are collected and entered into the database, the total number of potentially relevant articles per 100 search results will be calculated and plotted. The search continues, considering new articles in groups of 100 returns at a time to plot potentially relevant articles per unit of search effort. This step will be conducted during the screening process described below. In this way, the number of new, potentially relevant returns that will be discovered with continued effort can be estimated. Once the asymptote of the curve has been reached (no new relevant articles revealed for 3 groups of 100 search returns evaluated), searching in this data base will discontinue .
Article screening and study inclusion criteria
Article screening will occur in two steps. First, the title and abstract will be reviewed for potentially relevant articles. Second, the full text will be read from those screened during step one for relevant data. Initial screening will be conducted by two members of the research team until consistency in screening is established between screeners. Consistency will be measured using the Kappa statistic, which measures the degree of agreement between two coders . This systematic map process will implement two to four coders. All coders will search and screen the same river and the kappa statistic will be calculated. Criteria and differences between included article sets will be reviewed until kappa statistic values return moderate to high values, > 0.5 . Meetings to discuss search strategy and study inclusion will occur at regular intervals to maintain consistency throughout the search and study inclusion.
The inclusion criteria described below will be applied during the search process for collecting potentially relevant articles and then screening collected articles for inclusion in the final geodatabase. The number of all included and excluded articles will be recorded at each stage of the screening and study inclusion process per the PRISMA flow chart .
Study inclusion criteria
Not river related.
No information provided on fish biomass.
No or insufficient location information provided. Sufficient location information includes information (text description, coordinates, or a map) to pinpoint a location or specific area on a map where fish were extracted.
Insufficient methodological information to determine how data was acquired.
Is primary research, a review, a dataset, a book, or a report
Was published between 1950 and 2016.
The start date of 1950 was selected because it is also the first year that FAO provides global fisheries statistics .
The article contains species-specific and location-specific information about fish biomass.
In order to be included in the final database and map, a study must meet all of the following criteria:
River or river aquaculture fish species (as identified by Fishbase.org).
Capture/extraction of populations and communities of fish for food, income, or recreation.
Field names and definitions for data collected through the systematic map process
DOI or assigned reference number
(Metadata) artificial sequence number, linked to metadata table. RIVERID is derived from on NaturalEarth Rivers Database
Segment ID from the river zones. these zones were defined in a separate modeling analysis based on a k-mean plus cluster algorithm where cluster were derived based on six different bio-physical parameters of the rivers. A separate manuscript regarding this modeling effort is under preparation
Fish_Catch_record sequence number (unique)
Beginning date of fish data. Format: month/year example: 06/2016
End date of fish data. Format: month/year example: 06/2016
Is the date estimated? (1 = yes, 2 = no)
Latitude coordinate of fish catch in decimal degree
Longitude coordinate of fish catch in decimal degree
Original coordinate or location data from the reference
Is there a map showing the location of data collection? (1 = yes, 2 = no)
Species full Latin name. Enter “Mixed Catch” if specific species names are not provided. Example: Schizodon fasciatus
Number of individual fish caught. Enter N/A if number is not available
Select type of species (1 = native, 2 = non-native, 3 = article does not specify). If a report combines multiple fisheries, catch from each fishery will be recorded as separate entries
If introduced species then the year this species introduced in this river system, as determined by fishbase.org
Select the reason for fish capture (1 = artisanal, 2 = commercial, 3 = recreational, 4 = scientific study, 5 = subsistence, 6 = aquaculture, 7 = others)
The numeric value for the weight of the fish catch. The unit of weight is recorded in the field FISH_CATCH_UNIT
Select the weight unit reported by the article
Fish biomass, in kg. Calculated from field “FISH_CATCH_WT”
What area was sampled (include units)
Fish biomass, in kg/ha or X unit
The numeric value for the total biomass captured (including fish and other species). Enter N/A if not available
Select the weight unit reported by the article
Total biomass captured in the haul in KG (including fish and other species). Enter N/A if not available
Select the type of gear used to capture the fish species (1 = trawl, 2 = net, 3 = traps, 4 = line, 5 = electrofishing, 6 = other)
Numerical value for the gear size
Select the gear size unit reported by the article
Mesh size or gear size in centimeters
Number of boats or gears used for the survey
Number of hours or days spend in fishing (days as 24 h)
Relevant study designs
Quantitative research including experimental, quasi-experimental, observational studies will be included. Secondary studies including literature reviews and systematic reviews will be used to identify additional primary sources of information.
The original source of the data and type of organization (non-governmental, governmental, etc.) will be included in the final database. A list of articles excluded at full text review with reasons for exclusion will be provided.
Study quality assessment
Because of variation in fish harvest methods and differing purpose for data collection in peer-reviewed and grey literature, critical appraisal will not be applied to this systematic map. However, descriptive and demographic information about researchers and data collection will be captured as they may be pertinent for how the data are used in modeling projects or estimations. Notes regarding the methodological descriptions will also be collected, including reliability of sources.
Data coding strategy
The following information will be collected from each article, when available. Other categories or target information may be added during the search process.
Capture effort and methods fields
Fishing effort, gear type and size, vessel type and size, sampled area and location.
Subsistence, commercial, aquaculture, recreation, research, funding source.
Information type fields
Primary information (i.e., the report authors collected the information themselves), Secondary information; article reports data collected by another party.
Author affiliations, research question or objective, outcome or conclusion, replication present or absent, control present or absent, review (R), before/after (BA), comparator/intervention (CI), before/after/comparator/intervention (BACI), randomized controlled trial (RCT), objective or purpose of data collection.
Regarding the spatial component of fish biomass extraction, this information will consist of point locations, sets of point locations, areas, general descriptions, and river or watershed level scales. If the specific area cannot be determined from the information provided, that article will not meet study inclusion criteria and will be excluded from the final geodatabase. All other data will be included in the format provided by the original documentation. The final geodatabase will consist of point, multi-point, polygon, and multi-polygon shapefiles. The original spatial description, map, or coordinate information will be provided in the final geodatabase along with the spatial information. Changes in fish biomass over time or time-series data will include individual entries for each time point.
Intercoder reliability will be established by comparing extracted data between researchers. Table 5 provides the field names and definitions of the data targeted for extraction from the search results. All persons contributing to data collection will be provided the same set of 20 articles and the actual data extracted will be compared. Discrepancies in collected data will be discussed and assessed until data collection is consistent. Other types of data may be added as identified by the search process. Data from these sources will then be synthesized into a geodatabase.
Study mapping and presentation
The systematic map database will be presented as a geodatabase that will be open-access and hosted by USGS Sciencebase. The geodatabase will be available as both a file geodatabase and a series of folders. All files within the geodatabase will consist of shapefiles, which are not proprietary. This systematic map protocol will accompany the geodatabase as metadata. Additionally, a systematic map describing the data collection process and results of the search. A geographic map of data density and data collected will review the distribution of information to identify knowledge gaps or concentrations of information and also address the temporal scale of available information. Understanding the distribution of current information can help target future studies to fill these gaps and reduce redundant data collection. This information could also be used to frame systematic review questions and research regarding river fisheries.
CLR led map protocol development and will oversee literature search and data extraction. ZB, AL, and WT conceptualized the original research project. YCK provides expertize in Mandarin language and inland fisheries research in Asia. All authors contributed to protocol design, manuscript writing. All authors read and approved the final manuscript.
We thank Ian Cowx (University of Hull), Rachel Ainsworth (University of Hull), and NCCWSC staff for their assistance with refining this search methodology. We also thank Jessica Taylor for an internal USGS review, anonymous journal-selected reviewers, and the journal editors for their constructive feedback to improve this manuscript. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the US. Government. Its content is deliberative and predecisional, so it must not be disclosed or released by reviewers. Because the manuscript has not yet been approved for publication by the US Geological Survey (USGS), it does not represent any official USGS finding or policy.
The authors declare that they have no competing interests. If a reviewer is an author on a potentially relevant article, he or she will not be involved in the decisions regarding the inclusion of the article in the database.
Availability of data and materials
Consent for publication
Ethics approval and consent to participate
This work was funded by the US Geological Survey’s National Climate Change and Wildlife Science Center (NCCWSC).
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
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