Brandon L. Eder

Fish community response to floodplain inundation in a regulated river

Floodplain connectivity has been identified as an important element of river ecosystem function for enhancing biological productivity, yet most of the worlds large rivers have been managed to reduce river–floodplain connectivity to protect human interests. Flow events in the Missouri River basin during the summers of 2010 and 2011 offered a unique opportunity to investigate the influence of floodplain connectivity on fish communities. The floods created aquatic habitats not generally available on the main stem and the magnitude and duration of the 2011 event have not occurred since the main-stem dams were closed. Therefore, the objectives were to: (1) document species use on available floodplain habitats and assess age-0 fish presence, (2) compare spatial and temporal distribution of fish species, and (3) evaluate fish community responses at different discharges. Age-0 fish dominated the fish community during the 2010 and 2011 floods, representing 90% and 94% of all fish collected each year. Species composition during the 2011 flood was different above and below the Platte and Missouri rivers confluence (ANOSIM; r = 0.211; p < 0.001) and between individual sites (r = 0.667; p < 0.001) but did not change temporally (r = 0.086; p = 0.244). Comparison of the age-0 fish community response to varying water levels also differed (r = 0.619; p = 0.038) annually. The effects of this flood on the fish community of the Missouri River initially appear to have been beneficial for the native fish community; however, continued research and evaluation will verify the floods effects.

Use of Geographic Information Systems by Fisheries Management Agencies

ABSTRACT Use of geographic information systems (GIS) in fisheries science has increased in prevalence since its introduction in the late 1980s, but use among and within fisheries management agencies has not been quantified. We surveyed 89 administrators of fisheries management agencies in the United States and Canada to determine the current status of GIS in fisheries management and received 54 responses (61% return rate). Survey respondents indicated that GIS was used to help manage fish populations, and 63% of respondents believed that GIS was either “very useful” or “extremely useful” for meeting agency objectives. However, most GIS work conducted by fisheries management agencies was executed by few individuals within the agency or by contracted service. Barriers preventing more widespread use by managers within agencies included lack of knowledge or training and limited time to use GIS in job duties. Our results suggest that GIS is an important tool for fisheries management. Further, GIS use within an...

Using Lindgren–Pitman Hook Timers to Understand the Dynamics of Trotline Catches in a Large River

Abstract Trotlines have historically been used by commercial fishers to target ictalurids and have recently been shown to be effective for collecting sturgeons Scaphirhynchus spp. However, little is known about the gear–fish interaction after trotlines are deployed. Therefore, the objectives of this study were to determine whether trotlines equipped with Lindgren-Pitman (LP) hook timers could withstand harsh riverine conditions and whether catch rates, retention rates of hooked fish, capture times of targeted species, and bycatch would be affected. Our results showed no difference between standardized trotlines and trotlines with hook timers and indicated that 31% of pulled hook timers resulted in no fish being collected. Hook timers were activated by 69% of all the fish collected. The majority of fish collected were shovelnose sturgeon S. platorynchus (77%), of which 70% activated the timer. The fork length of the shovelnose sturgeon that did activate the timer (571.0 ± 60.1 mm [mean ± SE]) did not diffe...

Use of Constructed Side Channels of the Missouri River (Nebraska) by Age-0 Blue Sucker (Cycleptus elongatus)

ABSTRACT The blue sucker (Cycleptus elongatus) is listed as threatened in the state of Nebraska, and little is known about its life history. Nebraska Game and Parks Commission monitoring crews collected 13 age-0 blue suckers in three constructed side channels of the Missouri River from 2006 to 2008. Eleven of the 13 fish were sampled in shallow areas (<0.6 m) associated with bank-lines and vegetation and containing little to no flow (<0.10 m/s).

Determining Detection Requirements for Individuals Used in Categorical Resource Selection Analyses

ABSTRACT Resource selection analyses of telemetry data are often conducted on categorical measurements of use and availability. Refinement of early resource selection analysis techniques has resulted in use of individuals as the sample unit rather than the number of telemetry detections. However, the minimum number of telemetry detections required for an individual animal to be included as a sample unit must reflect the number of detections needed to accurately describe the individuals resource use. We developed a method to determine the minimum number of detections required to accurately describe categorical resource use of an animal. The mean standard selection ratio (MSSR) described herein can be used to effectively design telemetry projects and efficiently allocate field resources by knowing, a priori, the number of telemetry detections needed to explain resource selection for individual animals and ultimately for an animal population. Additionally, the MSSR technique can be used following data collection to determine the detection level needed for inclusion of individuals in categorical resource selection analyses.

Temporal Trends of Channel Catfish Population Characteristics in the Missouri River, Nebraska

Abstract Channel catfish (Ictalurus punctatus) are a popular target for Nebraska anglers, and the proportion of Nebraska anglers targeting catfish is consistently 50% or greater on an annual basis. Commercial fishing for channel catfish was legal on the Missouri River, in Nebraska, from the 1800s until 1992. Several studies have been published regarding channel catfish population characteristics in this reach prior to the closure of commercial fishing; however, there have been no long-term assessments done post-closure. There is concern among anglers and managers about numbers and size of channel catfish in the Missouri River and a desire to better understand population dynamics in order to better manage channel catfish stocks. The goal of this study was to assess spatial and temporal changes in population characteristics of channel catfish in the Missouri River, Nebraska from 1998 – 2013. Specifically, we asked: (1) did channel catfish population characteristics differ among four reaches of the river from 1998 to 2013 and (2) did channel catfish population characteristics exhibit any temporal trends within reaches from 1998 to 2013? We found channel catfish in Nebraska portions of the Missouri River are characterized by slow growth and high mortality. The majority of fish sampled were age-3 or younger and fish age-6 or older were rare. Mean lengths have decreased since the early 1990s and are similar to mean lengths before closure of commercial fishing. Relative abundance decreased in two reaches and was below the 15 y mean in all reaches from 2008-2013. We recommend management goals and objectives be updated and individual goals and objectives intended to decrease mortality and improve size structure be developed for the four study reaches.

An Introduction to Free Geographic Information Systems in Fisheries Science

Geographic information systems (GIS) are powerful tools for analysis and interpretation of spatial data commonly encountered in fisheries science. We presented details of GIS use in fisheries management in a prior study and found cost to be a factor limiting GIS use. This article introduces fisheries managers to free or open-source GIS. Free or open-source GIS are readily available, powerful tools capable of performing a variety of spatial analyses. We strongly encourage managers wishing to perform spatial analyses, but who are unable to purchase software, to consider free GIS.