Bait-bucket introductions" related to the fishing bait industry are the suspected primary cause of alien (non-indigenous) crayfish introductions that have damaged North American aquatic ecosystems. Our 2008 survey of U.S. and Canadian fisheries agencies revealed that 49% of respondents reported aquatic resource problems that were believed to have been caused by bait-bucket introductions of alien crayfishes. Most respondents reported existing regulations designed to address those problems; however, only 4% prohibited the use of live crayfish bait. Our 2002-2007 examination of Missouri bait shops revealed sales of illegal and invasive alien crayfishes by bait shop proprietors who could not identify the species they were selling. Fisheries agencies should consider more effective bait regulations and education to prevent negative impacts to aquatic biodiversity, habitat, and fisheries that can result from alien crayfish introductions. La industria de la carnada como potencial vector de introduccion de langostino: reconocimiento del problema por agencias de pesquerias y una evaluacion en Missouri RESUMEN:Se sospecha que la introduccion de especies exoticas a traves de cubetas con carnada, ha impactado negativamente los ecosistemas acuaticos de Norteamerica. Un muestreo que realizamos en el 2008 a agencias de pesquerias en Canada y Estados Unidos de Norteamerica, revelo que el 49% de los corresponsales reportaron problemas relacionados a recursos acuaticos que se cree fueron causados por introduccion de langostinos exoticos en cubetas con carnada. La mayor parte de los corresponsales reportaron la existencia de regulaciones para abordar el problema; sin embargo, solo el 4% de estas prohibe el uso de langostinos vivos como carnada. Nuestro examen realizado a tiendas de carnada en Missouri durante el periodo 2007-2007, revelo venta de langostinos ilegales e invasivos por parte de los propietarios de las tiendas, quienes no pudieron identificar las especies que vendian. Las agencias de pesquerias debieran contemplar regulaciones y programas de educacion mas efectiva en cuanto al uso de carnada para prevenir los impactos negativos que la introduccion de langostinos exoticos tiene sobre la biodiversidad acuatica, los habitats y las pesquerias.

Nearly 400 rock rip-rap grade control structures (hereafter GCS) were recently placed in streams of western Iowa, USA to reduce streambank erosion and protect bridge infrastructure and farmland. In this region, streams are characterized by channelized reaches, highly incised banks and silt and sand substrates that normally support low macroinvertebrate abundance and diversity. Therefore, GCS composed of rip-rap provide the majority of coarse substrate habitat for benthic macroinvertebrates in these streams. We sampled 20 sites on Walnut Creek, Montgomery County, Iowa to quantify macroinvertebrate assemblage characteristics (1) on GCS rip-rap and at sites located (2) 5-50 m upstream of GCS, (3) 5-50 m downstream of GCS and (4) at least 1 km from any GCS (five sites each). Macroinvertebrate biomass, numerical densities and diversity were greatest at sites with coarse substrates, including GCS sites and one natural riffle site and relatively low at remaining sites with soft substrates. Densities of macroinvertebrates in the orders Ephemeroptera, Trichoptera, Diptera, Coleoptera and Acariformes were abundant on GCS rip-rap. Increases in macroinvertebrate biomass, density and diversity at GCS may improve local efficiency of breakdown of organic matter and nutrient and energy flow, and provide enhanced food resources for aquatic vertebrates. However, lack of positive macroinvertebrate responses immediately upstream and downstream of GCS suggest that positive effects might be restricted to the small areas of streambed covered by GCS. Improved understanding of GCS effects at both local and ecosystem scales is essential for stream management when these structures are present. RightsWorks produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted. ABSTRACTNearly 400 rock rip-rap grade control structures (hereafter GCS) were recently placed in streams of western Iowa, USA to reduce streambank erosion and protect bridge infrastructure and farmland. In this region, streams are characterized by channelized reaches, highly incised banks and silt and sand substrates that normally support low macroinvertebrate abundance and diversity. Therefore, GCS composed of rip-rap provide the majority of coarse substrate habitat for benthic macroinvertebrates in these streams. We sampled 20 sites on Walnut Creek, Montgomery County, Iowa to quantify macroinvertebrate assemblage characteristics (1) on GCS rip-rap and at sites located (2) 5-50 m upstream of GCS, (3) 5-50 m downstream of GCS and (4) at least 1 km from any GCS (five sites each). Macroinvertebrate biomass, numerical densities and diversity were greatest at sites with coarse substrates, including GCS sites and one natural riffle site and relatively low at remaining sites with soft substrates. Densities of macroinvertebrates in the orders Ephemeroptera, Trichoptera, Diptera, Coleoptera and Acariformes were abundant on GCS rip-rap. Increases in macroinvertebrate biomass, ...

Over 400 riprap grade control structures (GCSs) have been built in streams of western Iowa to reduce erosion and protect bridges, roads, and farmland. In conjunction with a companion study evaluating fish passage over GCSs in Turkey Creek, we evaluated the differences in fish assemblage and habitat characteristics in reaches immediately downstream from GCSs (GCS sites) and reaches at least 1 km from any GCS (non‐GCS sites). The GCS sites were characterized by greater proportions of pool habitat, maximum depths, fish biomass, and abundance of juvenile largemouth bass Micropterus salmoides than were non‐GCS sites. Index of biotic integrity (IBI) scores were poor or fair (<43 on a 0–100 scale) and not significantly different between the GCS and non‐GCS sites. Additionally, we investigated both the longitudinal changes in fish assemblages in this GCS‐fragmented stream and the changes in fish assemblages after slope modifications of three GCSs to facilitate fish passage. Thirteen fish species were present throughout the study area, whereas another 15 species exhibited truncated distributions not extending to the most upstream sampling location. After modification of the GCSs, IBI scores increased at seven of nine sites (mean increase = 4.6 points). Also, channel catfish Ictalurus punctatus were detected 7.3 km upstream at sites where, 2 years before GCS modification, they had been absent from collections. Given the number and distribution of GCSs in western Iowa streams, understanding the effects of these structures is vital to the conservation and management of fish assemblages in this and other regions where GCSs or similar structures are used.

Grade control structures (GCSs) are commonly used in streams of western Iowa to control bank erosion and channel headcutting but may be barriers to fish passage. From May 2002 to May 2006, we used mark-recapture methods to evaluate fish passage over a total of five GCSs, ranging in slope (run : rise) from 13:1 to 18:1 in Turkey Creek, Cass County, Iowa. Three structures, over which limited fish movement was documented from 2002 to 2004, were modified in the winter of [2004][2005] to facilitate fish passage. Before modification, the majority of recaptured fish were recaptured at the station where they were originally marked; only 1% displayed movement between sites and either upstream or downstream over a GCS. After modification fish passage improved, 14% of recaptured fish displayed movement either upstream or downstream over a GCS. Individuals of four target species-channel catfish Ictalurus punctatus, yellow bullhead Ameiurus natalis, black bullhead A. melas, and creek chub Semotilus atromaculatus-passed over at least one modified structure. The majority of documented movements over GCSs were in the upstream direction and occurred in late spring and early summer, when streamflow was relatively high. Although we documented low numbers of fish passing both upstream and downstream over GCSs, these structures are probably barriers to fish movement during periods of low flow and when there is a structural failure, such as in-channel movement of riprap. Grade control structures are pervasive in western Iowa streams; nearly every low-order stream contains at least one instream structure. To sustain fish populations, management efforts should focus on constructing or modifying GCSs to allow fish passage. RightsWorks produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted. PLEASE SCROLL DOWN FOR ARTICLETaylor & Francis makes every effort to ensure the accuracy of all the information (the "Content") contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis.The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content.This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is e...

This paper summarizes research from separate studies of fish passage over weirs (Larson et al., 2004;Litvan, 2006; Litvan, et al., 2008a-c) and weir hydraulics (Papanicolaou and Dermisis, 2006; Papanicolaou and Dermisis, in press). Channel incision in the deep loess region of western Iowa has caused decreased biodiversity because streams have high sediment loads, altered flow regimes, lost habitat, and lost lateral connectivity with their former floodplains. In-stream grade control structures (GCS) are built to prevent further erosion, protect infrastructure, and reduce sediment loads. However, GCS can have a detrimental impact on fisheries abundance and migration, biodiversity, and longitudinal connectivity. Fish mark-recapture studies were performed on stretches of streams with and without GCS. GCS with vertical or 1:4 (rise/run) downstream slopes did not allow fish migration, but GCS with slopes ≤ 1:15 did. GCS sites were characterized by greater proportions of pool habitat, maximum depths, fish biomass, slightly higher index of biotic integrity (IBI) scores, and greater macroinvertebrate abundance and diversity than non-GCS sites. After modification of three GCS, IBI scores increased and fish species exhibiting truncated distributions before were found throughout the study area. Another study examined the hydraulic performance of GCS to facilitate unimpeded fish passage by determining the mean and turbulent flow characteristics in the vicinity of the GCS via detailed, non-intrusive field tests. Mean flow depth (Y) and velocity (V) atop the GCS were critical for evaluating GCS performance. Turbulent flow measurements illustrated that certain GCS designs cause sudden constrictions which form eddies large enough to disorient fish. GCS with slopes ≤ 1:15 best met the minimum requirements to allow catfish passage of a flow depth of ≥ 0.31 m and a mean flow velocity of ≤ 1.22 m/s. RightsWorks produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted. ABSTRACTThis paper summarizes research from separate studies of fish passage over weirs (Larson et al., 2004;Litvan, 2006; Litvan, et al., 2008a-c) and weir hydraulics (Papanicolaou and Dermisis, 2006; Papanicolaou and Dermisis, in press). Channel incision in the deep loess region of western Iowa has caused decreased biodiversity because streams have high sediment loads, altered flow regimes, lost habitat, and lost lateral connectivity with their former floodplains. In-stream grade control structures (GCS) are built to prevent further erosion, protect infrastructure, and reduce sediment loads. However, GCS can have a detrimental impact on fisheries abundance and migration, biodiversity, and longitudinal connectivity. Fish mark-recapture studies were performed on stretches of streams with and without GCS. GCS with vertical or 1:4 (rise/run) downstream slopes did not allow fish migration, but GCS with slopes ≤ 1:15 did. GCS sites were characterized by gr...