Our research focuses on the distribution, movements, reproduction, life history, behavior, or ecology of freshwater or anadromous fishes, adults as well as embryos, larvae, and juveniles. LFL is especially interested in studies to document fish reproduction; spawning behavior, seasons, habitats, and requirements; nursery grounds; and early-life-stage distribution and habitat utilization. LFL staff are experienced in the use of various fish, invertebrate, and water-quality sampling gear and techniques (including drift and tow netting, light trapping, electrofishing, and radiotelemetry) and have worked in rivers, streams, reservoirs, and lakes (including the Great Lakes) of northeastern, northcentral, midwestern, and southwestern U.S. Most LFL field work has involved endangered fishes in the Upper Colorado River System, Great Plains stream-fish communities, fishes of Colorado’s eastern slope, and aquatic toxicity concerns at various sites in the Northcentral and Rocky Mountain Regions. Although recent LFL field research has been regional for logistical reasons, field projects elsewhere in North America and on other continents will be considered.

Assessments include description, quantification of physico-chemical attributes, availability, and utilization. Recent investigations include work on nursery habitats in the Green River, Utah, winter-habitat utilization by adult Colorado squawfishPtychocheilus lucius in the Yampa River (latter based on radiotelemetry observations), evaluation of trophic dynamics of wetlands potentially used by endangered fishes of the Upper Colorado River Basin, and assessments of potential habitat developments or improvements for all life stages of endangered species.

Studies include various aspects of fish biology or life history with emphasis on early-life stages. Most investigations involve living material but some are based on preserved collections. Experimentation with living organisms requires special considerations and facilities. LFL is familiar with and follows federal and University animal care and use guidelines. LFL is also familiar with permitting requirements for importation of fish from outside Colorado and the holding and use of endangered species. Past and on-going investigations include age and growth analyses (including analysis of daily growth increments in the otoliths of larval and early-juvenile fish), food habits and preferences, behavior (response to various physical, chemical, or biological stimuli), habitat preferences, predation, competition, and drift.

Our goal is to determine effects of inorganic and organic contaminants on fish and aquatic invertebrates. LFL has experience with contaminant investigations at a variety of environmental scales, from laboratory toxicity tests to semi-controlled field mesocosm studies to field surveys covering entire watersheds. Studies have included 4-day acute and 32-day early-life-stage toxicity tests with endangered fishes, field evaluation of effects of aerial insecticide applications on fish and aquatic invertebrates in ponds and streams, effects of heavy-metal contaminants on olfaction of endangered fishes, and ecological risk assessment of aerial insecticide applications on endangered fishes in the Green River subbasin, Colorado and Utah.

Such techniques include development, refinement, or adaptation and testing. LFL research includes the adaptation, validation, and testing of otolith aging and chemical-marking techniques for use with early-life stages of endangered species in the Upper Colorado River System. It also has refined drift nets, designed and specified modifications to light traps, tested light-trap efficiency, and worked on the development of biodegradable, digestible and non-toxic “beads” for use in extensive passive drift investigations and experiments to evaluate adverse effects of electrofishing on the young of endangered species.

These studies document morphological development, ontogenetic events, and characters of diagnostic or systematic value. Expertise with and access to florescence and scanning-electron microscopy, computer-image measurement and analysis, specimen clearing and skeletal staining techniques, and PCR processing and m-DNA analysis enhance capabilities. Published investigations include work on early-life stages of many cypriniform fishes (minnows and suckers) in southwestern U.S. with emphasis on threatened and endangered species, salmonids (trouts) in Colorado, cottids (sculpins) in eastern Canada and the Great Lakes, hiodontids (mooneyes) and gadids (cod) in northcentral U.S. and the Great Lakes; aphredoderids (pirate perch) in southeastern U.S., and acipenserids (sturgeons) of the east coast and Mississippi and Missouri River Systems.

This allows for identification of fish larvae on a site-specific or broader basis. LFL has developed a standardized, but flexible, format for species accounts with detailed three-view, continuous-tone graphite and ink drawings, and summary tables for standardized morphometric, meristic, and developmental-state characters. Keys can be either fixed and printed or computer-interactive and provided on personal-computer floppy diskettes. Published guides or keys cover larvae and early juveniles of cypriniform fishes in the Upper Colorado River System of Colorado; catostomids (suckers) of the Pyramid Lake, Utah Lake, and Upper Colorado River Basins; and common salmonids (trouts) in Colorado (and much of North America).

We pay particular attention to eggs, larvae, reproduction, and related topics. Recent work includes a review of Colorado River ecology, endangered species management, status of the razorback sucker Xyrauchen texanus, dissolved-oxygen requirements for early-life stages of South Platte River fishes, the adverse effects of electrofishing on fish (embryos through adults), and a review of factors that might limit distribution of nonnative fishes in the Upper Colorado River System.

We help prepare bibliographies, especially those related to fish reproduction, early-life history, and development. Recent compilations include a bibliography of bibliographies on fish reproduction and early-life history, a listing of major early-life-history references with sources and costs, dissolved-oxygen literature from 1985-1991, electrofishing, and (in progress for the Early Life History Section of the American Fisheries Society) a voluntary effort to update the 1988 Hoyt Bibliography of early-life-history literature as a bibliographic database for personal computers.