Comparison of electrofishing and trammel netting variability for sampling native fishes

C.P. Paukert

doi:10.1111/j.0022-1112.2004.00575.x

Home/Archive/USGS

USGS · 70026154

Comparison of electrofishing and trammel netting variability for sampling native fishes

C.P. Paukert

View original source ↗Export metadata ↓

Abstract

The variability in size structure and relative abundance (CPUE; number of fish ≥200 mm total length, L T , collected per hour of electrofishing or trammel netting) of three native Colorado River fishes, the endangered humpback chub Gila cypha , flannelmouth sucker Catostomus latipinnus and bluehead sucker Catostomus discobolus , collected from electrofishing and trammel nets was assessed to determine which gear was most appropriate to detect trends in relative abundance of adult fishes. Coefficient of variation (CV) of CPUE ranged from 210 to 566 for electrofishing and 128 to 575 for trammel netting, depending on season, diel period and species. Mean CV was lowest for trammel nets for humpback chub ( P = 0·004) and tended to be lower for flannelmouth sucker ( P = 0·12), regardless of season or diel period. Only one bluehead sucker >200 mm was collected with electrofishing. Electrofishing and trammel netting CPUE were not related for humpback chub ( r = −0·32, P = 0·43) or flannelmouth sucker ( r = −0·27, P = 0·46) in samples from the same date, location and hour set. Electrofishing collected a higher proportion of smaller (<200 mm L T ) humpback chub ( P < 0·001), flannelmouth suckers ( P < 0·001) and bluehead suckers ( P < 0·001) than trammel netting, suggesting that conclusions derived from one gear may not be the same as from the other gear. This is probably because these gears fished different habitats, which are occupied by different fish life stages. To detect a 25% change in CPUE at a power of 0·9, at least 473 trammel net sets or 1918 electrofishing samples would be needed in this 8 km reach. This unattainable amount of samples for both trammel netting and electrofishing indicates that detecting annual changes in CPUE may not be practical and analysis of long‐term data or stock assessment models using mark‐recapture methods may be needed to assess trends in abundance of Colorado River native fishes, and probably other rare fishes as well.

Explore related subjects

Journal of Fish Biology Article

Keep this discovery

Explore connections, maps & timelines

BibTeX RIS

C.P. Paukert. 2004-12-20. Comparison of electrofishing and trammel netting variability for sampling native fishes. https://doi.org/10.1111/j.0022-1112.2004.00575.x

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related USGS reports

USGS2026

Black Carp Mylopharyngodon piceus reproductive development and maturation in the Mississippi River basin

Black Carp Mylopharyngodon piceus are native to most major east Asian drainages and are internationally cultured for use as a food-fish or a biological control for molluscs. We describe the reproductive biology of Black Carp from the growing invasive population in the Mississippi River basin through examination of incidental commercial fisheries and biologist captures. Our objectives were to assess (1) reproductive development by combined macroscopic and histological staging to compare reproductive maturation by total length, estimated age, and latitude; (2) population functions of gonadosomatic index, length and age, and weight and length relationships; and (3) absolute fecundity. We identified length as a better predictor of reproductive maturation than age, with variation among individuals, and between males and females, with higher probability of maturation anticipated for larger and older individuals predicted around 1050 mm total length (TL; 6 years) for females and 950 mm TL (5 years) for males ( n = 548). Proposed sizes and ages are representative minimum and should be interpreted with the understanding that spawning and recruitment success increase for older, more mature fish than in early stages. Observed growth rates were rapid relative to both native and introduced ranges. We confirmed that Black Carp are developmentally indeterminate batch spawners due to the simultaneous presence of advanced growth oocytes via histology and egg measurements, with preserved egg average diameters ranging from 0.395 to 3.215 mm ( n = 23). Absolute fecundity estimates ranged from 72,748 to 3,542,789 eggs across the 966 to 1412 mm TL size range of individuals, with substantial variability among individuals attributed to poor relative fecundity estimates. These results represent the first step in assessing the reproductive rates of Mississippi River Black Carp via the size of reproductive development and potential contributions through fecundity. The results and population rates presented here may be used or adapted for future studies on regional spawning phenology and reproductive development, or in population growth models for control.

Arkansas, Illinois, Indiana, Kentucky, Louisiana, ↗

USGS2026

Plasticity in the reproductive biology of Yellowstone cutthroat trout Oncorhynchus virginalis bouvieri in Yellowstone Lake following lake trout Salvelinus namaycush invasion

Yellowstone cutthroat trout Oncorhynchus virginalis bouvieri in Yellowstone Lake are the focus of intensive conservation efforts due to the threat of predation by invasive lake trout Salvelinus namaycush . Suppression gillnetting has reduced the abundance of predatory lake trout, and the Yellowstone cutthroat trout population is recovering. Long-term monitoring indicates the size structure of the population shifted following lake trout invasion, suggesting that reproductive demographic rates of Yellowstone cutthroat trout may have changed. Length at 50% probability of maturity, as assessed using histological analysis of gonadal tissue, was 479 mm (95% confidence interval [CI] 467–490 mm) for females and 406 mm (95% CI 386–430 mm) for males, compared to 330 mm for males and females historically. Currently, age at 50% probability of maturity is 6.6 for females and 5.4 for males. The rate of skipped spawning was 3% for females and 38% for males. Mean absolute fecundity was 2897 ovarian follicles/individual at present compared to 1141 ovarian follicles/individual before lake trout invasion. Mean relative fecundity was 2157 ovarian follicles/kg. This research illustrates the plasticity in the reproductive strategies of fishes as a result of an invasive species. Understanding the reproductive biology of fish populations is vital for effective fisheries management, and these results are integral to a population model that can be used to develop new conservation benchmarks for Yellowstone cutthroat trout.

Wyoming↗

USGS2025

Too hot for comfort: Elevated temperatures influence gene expression and exceed thermal tolerance of bigmouth shiners, Ericymba dorsalis

Environmental and associated ecosystem change may affect the persistence of fish species based on their ability to adapt to changing conditions, including decreasing flows and rising water temperatures. Exceeding the thermal tolerances of stream fish will likely result in a loss of ability to maintain metabolic processes. We evaluated the critical thermal maximum (CTmax) of bigmouth shiner ( Ericymba dorsalis ) and analysed the expression of heat shock protein 70 messenger RNA (mRNA) (HSP70) to quantify a thermal stress response over a gradient of temperatures (25°C–31°C). E. dorsalis HSP70 mRNA expression was upregulated in response to temperatures >25°C, indicating a stress response. This study supports the existence of a thermal stress threshold for E. dorsalis . The frequency at which this threshold is exceeded may increase under forecasted future climate scenarios for Nebraska.

Nebraska↗