Geology topics

Jack E. Williams

Publications and source records attributed to Jack E. Williams.

4 recordsLinked to original sources

USGS2020

A call for global action to conserve native trout in the 21st century and beyond

Trout and char (hereafter, trout ) represent some of the more culturally, economically and ecologically important taxa of freshwater fishes worldwide (Kershner, Williams, Gresswell, & Lobón‐Cerviá, 2019a ). Native to all continents in the Northern Hemisphere (as well as western Mediterranean Africa), trout belong to seven genera ( Oncorhynchus , Salvelinus, Salmo , Hucho, Parahucho, Brachymystax and Salvethymus ), which are distributed across more than 60 countries (Muhlfeld et al., 2019 ). Despite their broad importance as indicators of biodiversity in cold‐water ecosystems (Haak & Williams, 2013 ), as well as cultural icons for food and recreation, nearly half of the world's recognised trout species (IUCN, 2018 ) are imperilled or at risk of global extinction (Muhlfeld et al., 2018 , 2019 ). The root causes of their vulnerability include broad‐scale alteration of landscapes and watersheds, dams, overharvest, pollution, interactions with hatchery‐bred conspecifics and non‐native species. However, emerging threats such as climate change and related problems such as the spread of diseases and parasites pose significant challenges and uncertainties to native trout and their habitats (Kovach et al., 2016 ; Muhlfeld et al., 2018 ). Ultimately, conservation of native trout depends on understanding their diversity, a willingness to address threats at their root causes and implementing progressive conservation solutions that promote persistence of these iconic species in the face of growing human pressures.

Ecology of Freshwater Fish↗

USGS2018

Trout in hot water: A call for global action

Trout are one of the most culturally, economically, and ecologically important taxonomic groups of freshwater fishes worldwide (1). Native to all continents in the Northern Hemisphere, trout are a taxonomically diverse group of fishes belonging to 7 genera (Oncorhynchus, Salvelinus, Salmo, Hucho, Parahucho, Brachymystax, and Salvethymus) distributed across 52 countries. These coldwater specialists provide recreation and food to millions of people, and play important roles in ecosystem functioning and health (2). They are also extremely sensitive to human disturbances because they require cold, clean, complex, and connected habitats for survival and persistence (3) – all attributes that humans have substantially altered and degraded (4, 5). Despite their broad importance as societal icons and as indicators of biodiversity, many of the world’s trout species and lineages are endangered and some require immediate conservation efforts to reverse their precarious decline.

Science↗

USGS2016

Conservation of native Pacific trout diversity in western North America

Pacific trout Oncorhynchus spp. in western North America are strongly valued in ecological, socioeconomic, and cultural views, and have been the subject of substantial research and conservation efforts. Despite this, the understanding of their evolutionary histories, overall diversity, and challenges to their conservation is incomplete. We review the state of knowledge on these important issues, focusing on Pacific trout in the genus Oncorhynchus. Although most research on salmonid fishes emphasizes Pacific salmon, we focus on Pacific trout because they share a common evolutionary history, and many taxa in western North America have not been formally described, particularly in the southern extent of their ranges. Research in recent decades has led to the revision of many hypotheses concerning the origin and diversification of Pacific trout throughout their range. Although there has been significant success at addressing past threats to Pacific trout, contemporary and future threats represented by nonnative species, land and water use activities, and climate change pose challenges and uncertainties. Ultimately, conservation of Pacific trout depends on how well these issues are understood and addressed, and on solutions that allow these species to coexist with a growing scope of human influences.

Fisheries↗

USGS2011

Native fish conservation areas: A vision for large-scale conservation of native fish communities

The status of freshwater fishes continues to decline despite substantial conservation efforts to reverse this trend and recover threatened and endangered aquatic species. Lack of success is partially due to working at smaller spatial scales and focusing on habitats and species that are already degraded. Protecting entire watersheds and aquatic communities, which we term "native fish conservation areas" (NFCAs), would complement existing conservation efforts by protecting intact aquatic communities while allowing compatible uses. Four critical elements need to be met within a NFCA: (1) maintain processes that create habitat complexity, diversity, and connectivity; (2) nurture all of the life history stages of the fishes being protected; (3) include a long-term enough watershed to provide long-term persistence of native fish populations; and (4) provide management that is sustainable over time. We describe how a network of protected watersheds could be created that would anchor aquatic conservation needs in river basins across the country.

Fisheries↗