After nearly a century of people building dams on most of the world鈥檚 major rivers, artificial reservoirs now represent an immense freshwater footprint across the landscape. Yet, these reservoirs are understudied and overlooked for their fisheries production and management potential, indicates a study from the University of California, Davis.
The study, , estimates that U.S. reservoirs hold 3.5 billion kilograms (7.7 billion pounds) of fish. Properly managed, these existing reservoir ecosystems could play major roles in food security and fisheries conservation.
鈥淭here is a large amount of fish mass in U.S. reservoirs that are being overlooked, despite the value being comparable to fish harvest from fisheries around the world,鈥 said lead author Christine Parisek, a Ph.D. candidate in the 嘿嘿视频 Ecology Graduate Group and the Department of Wildlife, Fish and Conservation Biology.
States with most reservoir fish
For the study, the authors analyzed, digitized, ranked and classified reservoir data collected by the U.S. Army Corps of Engineers between the 1970s and 1990s, after dam construction had tapered off from its heyday of the 1940s to 1960s. The data include fish biomass and production rates from 301 reservoirs in the United States.
Southern U.S. reservoirs contained 1.92 billion kilograms (4.2 billion pounds) of fish. Reservoirs across the entire U.S. were estimated to contain 3.43 billion kilograms (7.6 billion pounds) of fish.
Most states show reservoir stock of at least 100 million kilograms (220 million pounds). The top five states with the most standing stock, or total weight, of reservoir fish are Texas, Arkansas, Oklahoma, Florida and South Dakota.
When total weight is adjusted for how much reservoir surface area is available in the state 鈥 similar to a per capita measure 鈥 Louisiana, Indiana, Alabama, Maryland and Illinois ranked highest.
The study also said the large mass of fish in U.S. reservoirs is significant for the global carbon cycle, as fish play important roles in carbon flux, food webs, nutrient cycling and energy transfer.
Managing amid challenging realities
The authors emphasize the study is not making an argument for prioritizing building reservoirs over protecting and restoring natural-flowing rivers. The study states: 鈥淓cological effects of dams have been overwhelmingly negative and represent one of the principal drivers of freshwater biodiversity loss at all scales.鈥&苍产蝉辫;
The study does suggest unrealized opportunities to better manage both natural and built ecosystems, given the realities of reservoirs鈥 continued existence, climate change, and the dire challenges facing native fish.
鈥淲e should be able to walk and chew gum,鈥 said fish ecologist and senior author Andrew Rypel, director of the 嘿嘿视频 Center for Watershed Sciences and professor in the Department of Wildlife, Fish and Conservation Biology. 鈥淲e should be able to decommission and remove some dams, and manage others for food and as important habitats.
鈥淚n a worst-case scenario where salmon go extinct and native fishes go away, these fisheries may be all we have left. It鈥檚 worth having some foresight about how to make them well managed and how to use these ecosystems to deliver value for the environment and for people.鈥
Additional authors include co-first author Francine De Castro, Jordan Colby and Steven Sadro of 嘿嘿视频, and George Leidy of consulting firm AECOM and Stillwater Science.
The study was funded by the National Science Foundation, 嘿嘿视频 Center for Watershed Sciences鈥 Bechtel Next Generation Funds, Agricultural Experiment Station of the University of California, and the California Trout and Peter B. Moyle Endowment for Coldwater Fish Conservation.
Media Resources
Media Contacts:
- Andrew Rypel, 嘿嘿视频 Center for Watershed Sciences, rypel@ucdavis.edu
- Christine Parisek, 嘿嘿视频 Wildlife, Fish and Conservation Biology, caparisek@ucdavis.edu
- Kat Kerlin, 嘿嘿视频 News and Media Relations, 530-750-9195, kekerlin@ucdavis.edu