Angler Behavior in Response to Management Actions on Nebraska Reservoirs
Natural resource agencies invest substantial resources to recruit anglersâthe Nebraska Game and Parks Commission is no different. However, there is little understanding of human motives for participating in angling activities. Even less is known about the effects of management actions on angler participation.
GoalsTo understand 1) the participation patterns of anglers on local and regional scales, and 2) how participation patterns of anglers influence fish populations.
A Creel Summit was held on August 6-7, 2013 to share the past five years of creel data, program statistics, and experience with faculty and staff with the Nebraska Game and Parks Commission and the University of Nebraska-Lincoln.
The project currently has four study components:
1. Statewide Angler Survey: Anglers were interviewed at Calamus Reservoir, Harlan County Reservoir, Lake McConaughy, Lewis and Clark Lake, Merritt Reservoir, and Sherman Reservoir from April through October, 2009â2013. These interviews providedcontinuation to long-term (>10â20 years) data sets that are valuable for assessment of temporal changes in angler participation. In particular, these extended data sets will allow for relational assessments of changes in angling participation with environmental conditions and management actions on large-scales.
In addition to the long-term assessments, anglers were interviewed at numerous smaller reservoirs. Effectively sampling smaller waterbodies is logistically difficultâthere are fewer anglers to contact, which creates statistical issues due to small sample size. Small reservoirs sampled at least one year during this study included the Fremont State Lakes, TaHaZouka Park Lake, Gracie Creek Pond, Willow Creek State Recreation Area, Skyview Lake, Cottonmill Lake, Johnson Reservoir, and Yanney Park Lake. These surveys will be used for assessment of current guidelines to sample small fisheries.
Angler interviews were also used to target some unique situations around the state. Our first unique situation occurred in the Republican River basin. Four reservoirs (Swanson, Enders, Red Willow, and Medicine Creek) were evaluated during 2009â2013 to identify possible changes in angler participation following a major drawdown at Red Willow due to safety concerns over the dam, which restricted access for several months. Lessons learned from these reservoirs will aide in understanding other situations across the state when access to a fishery is restricted. Our second unique situation occurred in the upper basin of the Niobrara River. Box Butte Reservoir was evaluated during 2010-2011 to quantify the participation patterns by spear fishermen following a change in the spear-fishing season and to identify changes in harvest of northern pike following a change in the size limit. Our third unique situation occurred in spring 2012 with the grand opening of Wanahoo Reservoir in Wahoo, NEârarely do brand new reservoirs open up. We interviewed anglers during 2012â2013 to quantify the impact of this new reservoir on the regional fishery, the spatial use of the reservoir by bank anglers, and how catch rates change when targeted fish become less naÃ¯ve to angling.
2. Regional Angler Survey: An intensive year-round survey was completed on 20 reservoirs in the Salt Valley region of southeast Nebraska during 2009â2012. This survey provided baseline data necessary to develop a model predicting temporal and spatial participation by anglers. This model will be especially useful for understanding changes in fishing pressure at specific reservoirs as influenced by conditions at nearby reservoirs. Additional modeling will bridge the gap between social and ecological sciences by using social network analysis to look at angler participation patterns across the Salt Valley region and the influence of a new reservoir, Lake Wanahoo, on the regional fishery. The number of anglers harvesting fish is small across the region, whereas effort is great in most reservoirs, especially those within Lincoln.
An intensive sampling effort was also conducted during October 2011 following the rainbow trout stocking in Holmes reservoir. These data were used to assess angler participation and catch rates on a daily time scale. Preliminary results indicate that these events increase angler effort for a period of 3â5 days and increase catch rates of rainbow trout for 1â2 days.
3. Angler Effects on Sexually-Dimorphic Fish Species: Differences in harvest between male and female fish can alter sex-specific rates of recruitment, growth, and mortality, and hence, the overall health of a fish population. Detailed information (species, length, total weight, age, sex, liver weight, and gonad weight) on harvested walleye, white bass, and white crappie was collected from Sherman and Calamus Reservoirs during spring 2009 and 2010. Sex-selective harvest (female-biased) was evident for white bass and white crappie, but not for walleye.
4. Estimates of Fish Population Size: An Important Link to Understanding Fish Harvest: Fishery biologists routinely monitor relative abundance of fish populations by assessing catch-per-unit-effort in standardized gears; they also routinely monitor harvest by estimating total number of fish kept by anglers within a year. Unfortunately, it is difficult to understand the effect of harvesting 20,000 walleye from a reservoir when only six walleye were captured in a gillnet that was set overnight during standard sampling. As such, we estimated population sizes for channel catfish in 10 Salt Valley reservoirs. In addition, we investigated the applicability of techniques commonly used by wildlife biologists to estimate bird and mammal abundance, for estimating abundance of fish. This was accomplished through computer-simulated sampling of modeled populations. We observed that a trade-off exists between accuracy and precision of population estimates with regard to area of individual samples and number of samples when overall effort remains constant. Ultimately, information on fish population sizes will be linked with information on angler use and harvest.