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Environmental Sciences

Nebraska Cooperative Fish and Wildlife Research Unit: Staff Publications

Growth

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Degree-Day Accumulation Influences Annual Variability In Growth Of Age-0 Walleye, Christopher S. Uphoff, Casey W. Schoenebeck, W. Wyatt Hoback, Keith D. Koupal, Kevin L. Pope Jan 2013

Degree-Day Accumulation Influences Annual Variability In Growth Of Age-0 Walleye, Christopher S. Uphoff, Casey W. Schoenebeck, W. Wyatt Hoback, Keith D. Koupal, Kevin L. Pope

Nebraska Cooperative Fish and Wildlife Research Unit: Staff Publications

The growth of age-0 fishes influences survival, especially in temperate regions where size-dependent over-winter mortality can be substantial. Additional benefits of earlier maturation and greater fecundity may exist for faster growing individuals. This study correlated prey densities, growing-degree days, water-surface elevation, turbidity, and chlorophyll a with age-0 walleye Sander vitreus growth in a south-central Nebraska irrigation reservoir. Growth of age-0 walleye was variable between 2003 and 2011, with mean lengths ranging from 128 to 231 mm by fall (September 30th–October 15th). A set of a priori candidate models were used to assess the relative support of explanatory variables using Akaike’s …


Effect Of Catch-And-Release Angling On Growth And Survival Of Rainbow Trout, Oncorhynchus Mykiss, K. L. Pope, G. R. Wilde, D. W. Knabe Jan 2007

Effect Of Catch-And-Release Angling On Growth And Survival Of Rainbow Trout, Oncorhynchus Mykiss, K. L. Pope, G. R. Wilde, D. W. Knabe

Nebraska Cooperative Fish and Wildlife Research Unit: Staff Publications

Catch-and-release angling is popular in many parts of the world and plays an increasingly important role in fish conservation efforts. Although survival rates associated with catch-and-release angling are well documented for many species, sublethal effects have been less studied. An experiment was conducted to directly assess the effects of catch-and-release angling on growth and survival of rainbow trout, Oncorhynchus mykiss (Walbaum). Catch-and-release events were simulated in laboratory tanks maintained at 15–16 °C with hooks manually placed in pre-designated locations in the mouths of the fish. There were no differences in standard length (P= 0.59) or wet weight (P=0.81) gained between …


Effect Of Catch-And-Release Angling On Growth Of Largemouth Bass, Micropterus Salmoides, K. L. Pope, G. R. Wilde Jan 2004

Effect Of Catch-And-Release Angling On Growth Of Largemouth Bass, Micropterus Salmoides, K. L. Pope, G. R. Wilde

Nebraska Cooperative Fish and Wildlife Research Unit: Staff Publications

Catch-and-release angling is popular in many parts of the world and plays an increasingly important role in management of recreational fisheries. Although the magnitude of catch-and-release mortality is well documented for many species, potential sublethal effects have been little studied. An experiment was conducted to assess directly the effects of catch-and-release angling on growth of largemouth bass, Micropterus salmoides Lacépède. Angling mortality was 0.00 ± 0.092% for largemouth bass caught on plastic grubs. There was no difference (P = 0.57) in weight gain between caught and uncaught fish over a 40-day angling and recovery period. Although catch-and-release angling appears to …


Back-Calculated Length-At-Age Estimates From Two Scale Radii, Keith L. Hurley, Kevin L. Pope, David W. Willis Jan 1997

Back-Calculated Length-At-Age Estimates From Two Scale Radii, Keith L. Hurley, Kevin L. Pope, David W. Willis

Nebraska Cooperative Fish and Wildlife Research Unit: Staff Publications

Variability in length-at-age estimates back-calculated from scales continues to be of concern to fishery scientists. Measurement transects used to back-calculate length at age have been recommended; however, specific scale and annuli radius measurements have not been evaluated for variability between different radii. Thus, the purpose of our study was to compare back-calculated length-at-age estimates determined from two different scale radii: one horizontally from the focus to the anterior-median edge and one diagonally from the focus to the anterior-lateral corner of the scale. No significant differences (P = 0.13 - 0.58 and P = 0.24 - 0.87) in backcalculated length-at-age estimates …


Seasonal Influences On Freshwater Fisheries Sampling Data, Kevin L. Pope, David W. Willis Jan 1996

Seasonal Influences On Freshwater Fisheries Sampling Data, Kevin L. Pope, David W. Willis

Nebraska Cooperative Fish and Wildlife Research Unit: Staff Publications

Fisheries managers often assess fish populations using catch per unit effort (CPUE), size and age structure, growth, and condition. For many freshwater fishes and common sampling gears, CPUE, size and age structure, and condition are highest in the spring and fall, while growth commonly is fastest during the summer growing season. However, there are exceptions to these general trends, especially in populations with erratic recruitment, growth, or mortality. At the least, CPUE, size and age structure, growth, and condition of fish should be expected to change with season, given the effects of variable recruitment, growth, and mortality. However, if recruitment, …