A Michigan State University-led team of scientists has assembled the North American Freshwater Migratory Fish Database, which brings together life history information on 1,250 species to inform conservation practices.
A paper chronicling the effort was published in the Journal of Biogeography.
The development of the database was led by Emily Dean, a doctoral student in the Department of Fisheries and Wildlife who works in the lab of professor Dana Infante.
"Freshwater fish migrations support natural and human communities across the globe," Dean said. "However, migratory populations are declining in response to barriers such as dams, culverts and road crossings, which reduce access to critical habitat in streams."
Migratory fish require certain habitats to complete life stages, and they become vulnerable when obstacles prevent entry to those locations. Compounding the problem, there has been a lack of detailed information on the life histories of many migratory species throughout North America, putting natural resources managers in less-than-ideal decision-making scenarios.
Historically, research and conservation has been aimed at economically and socially important species such as salmon and other diadromous fishes -- those that migrate between oceans and streams. Less attention has been placed on potamodromous fishes, which live their entire lives within freshwater stream systems.
"With these knowledge gaps in mind, we wanted to help other researchers find consistent, verified information on freshwater fish species, their migratory life histories and their habitats," Dean said.
Compiled using more than 280 books, journal articles, technical reports, theses and dissertations, the database describes the life histories of 1,250 migratory freshwater species. Among the abundance of new information, Dean said there were three key insights gleaned.
First, a recent global assessment of migratory fish populations showed North America having the smallest decline, but this determination was made factoring in only 30% of species now known to the continent. It's unclear to researchers where North America would place when considering a more robust list.
Secondly, using this database alongside information from the Amazon and Mekong River basins, global population estimates of diadromous fishes suggest they number less than half of their potamodromous counterparts, despite more conservation focus.
Finally, the species with the least amount of life history information are the most vulnerable, and these tend to be small-bodied fish such as minnows.
Additionally, the team found that roughly 25% of all North American freshwater species are migratory, with 25% of those being threatened or endangered as defined by the IUCN RedList in North America. The lesser-studied potamodromous fishes comprise more than 50% of the salmon and trout, sturgeon, sucker, pike, gar and lamprey fish families. This group represents two-thirds of all North America migratory species.
Researchers say that 44% of migratory fishes, such as minnows and other small-bodied species, need their life histories studied further to gain a better understanding of the challenges they face.
"Overall, the database provides a baseline estimate of the diversity of freshwater migratory fishes in North America," Dean said. "We believe the development of additional regional databases could produce a global estimate of the diversity of freshwater migratory fishes and their habitats that would benefit researchers, managers and conservationists worldwide."
The team consists of members from MSU; the Michigan Department of Natural Resources; the International Joint Commission, Great Lakes Regional Office; the U.S. Geological Survey; Nicholls State University; Kansas State University; the University of Delaware; the Ontario Ministry of Natural Resources and Forestry; Louisiana State University; the Pacific States Marine Fisheries Commission; the New Jersey Department of Environmental Protection; the University of Alaska Fairbanks; the U.S. Army Corps of Engineers; Utah State University; the University of New Mexico; and the University of Massachusetts Amherst.
Funding for the project was provided by the U.S. Geological Survey and Michigan State University.
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