Two New Papers Improve Estimates of Inland Fisheries

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Under-reporting inland fish harvests and underestimating the importance of inland fisheries impact how these vital resources are valued. Two new publications, co-authored by National CASC Research Fish Biologist Abby Lynch and Chief Doug Beard, address the need for accurate valuations of inland fisheries, both commercially and recreationally.

throwing net

Man throwing net in Lower Mekong River Basin (public domain).

Inland fisheries provide jobs, revenue, critical resources, and food security to communities around the world. Over 40% of reported global finfish production comes from inland fish and over 90% of inland fish catch is used for human consumption. From a nutritional perspective, common freshwater fishes offer protein and essential fatty acids that promote neural and cardiovascular health in humans. This has contributed to a global economic valuation of inland fisheries estimated at US$26 billion, with catches from inland fisheries reported to be at their highest ever in 2018 at 12 million tons. However, despite the importance of this resource, scientists believe this valuation fails to describe the true worth of inland fisheries from either commercial or recreational perspectives

Inland fisheries can range from small-scale activities for local consumption to large-scale commercial operations for modernized markets and export. The Food and Agriculture Organization (FAO) of the United Nations estimated that 11.6 million tons of fish were harvested through global inland commercial fisheries in 2016. However, several studies indicate that inland fish harvests are underestimated and under-reported worldwide. For larger fisheries, this may be due to inefficiencies in monitoring or reporting systems, unregulated or illegal fishing, or a desire to avoid taxation, while small-scale fishers may lack the ability to monitor harvest or rely on flawed methods for estimating harvest. These issues diminish our understanding of the economic and food value of inland commercial fisheries, with potential implications for the protection of inland fish habitats.

In the United States, for example, no comprehensive compilation of inland commercial fisheries exists because fish harvests are typically under-reported due to a lack of systematic data collection. While some areas, like the Great Lakes region, are monitored regularly, other U.S. territories lack any commercial fisheries data. This limits a broader understanding of U.S. fisheries, such as whether long‐term trends in fish harvests exist throughout the country. In a case study, co-authored by National CASC Research Fish Biologist Abby Lynch and Chief Doug Beard, researchers compiled all available existing data from inland commercial fisheries in each of the 50 United States to provide a complete estimate of national inland commercial fish harvest from 1990 to 2015. Results showed a small but important decline in harvest, with average harvests peaking in 1995 at a minimum of 49,951 tons. Both harvest and species composition varied regionally from 2009 to 2015, with the most fish being harvested from the eastern interior region of the country. Importantly, these statistics more than doubled those of the current national inland commercial fisheries harvests, indicating an underestimation of the value of inland commercial fisheries which may have consequences for policy decisions regarding water usage from competing sectors, like hydropower generation or agricultural irrigation.

Like commercial fisheries, inland recreational fisheries have a high economic worth valued globally at US$190 billion. Recreational fisheries are the dominant source of inland fish in developed nations and are likely a significant source of food worldwide, though this contribution is still poorly understood. Recreational fisheries are typically dispersed across any given landscape and fish harvest monitoring is generally limited to individual angler reports. Therefore, inland recreational fisheries are grossly underestimated at national and regional scales as a vital ecosystem service.

In a second paper, also, co-authored by Lynch and Beard, researchers address this knowledge gap by using 28‐year surveys for roughly 300 of Wisconsin’s inland lakes to develop a statistical model of inland recreational fish harvest. This model used the available data to predict inland fisheries harvests in unsurveyed lakes throughout the state. Results showed an estimated inland recreational Wisconsin lake fish harvest of 4,200 metric tons. Additionally, the estimated annual angler consumption rate for this region alone was almost equal to the total estimated United States per capita freshwater fish consumption. The approach these researchers developed can be used to guide science, policy, and management decisions on harvest levels to satisfy consumption needs as well as conserve natural resources.

This research supports the National CASC project “Improving National Estimates of Inland Recreational Harvest Using State Angler Survey Data”.

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