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C Katopodis - One of the best experts on this subject based on the ideXlab platform.
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sturgeon survival the role of swimming performance and fish passage research
Fisheries Research, 2019Co-Authors: C Katopodis, Lu Cai, David JohnsonAbstract:Abstract The rapid decline in sturgeon populations is largely a result of human activities, especially the proliferation of hydraulic structures and lack of fish passage systems effective for sturgeon. This review highlights: (1) the importance of sturgeon conservation; (2) the need for data on swimming performance, including capability, metabolism and kinematics; (3) the relevance and limitations of swimming performance data in designing fish passage systems; (4) the need for experiments to develop sturgeon Fishways that better reflect natural conditions. A proper understanding of swimming performance is crucial for designing effective fish passage systems. Although swimming performance and fish passage have been investigated for decades, knowledge and results have been limited by biological, methodological and analytical restrictions. To continue advancing passage effectiveness, continued research is necessary on sturgeon swimming performance and its interface with complex fishway hydraulics.
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retrofitting pool and weir Fishways to improve passage performance of benthic fishes effect of boulder density and fishway discharge
Ecological Engineering, 2014Co-Authors: Jose Maria Santos, C Katopodis, Paulo Branco, Teresa Ferreira, Antonio N PinheiroAbstract:Abstract Retrofitting, or the addition of features to existing Fishways to make them more suitable for upstream fish passage, is an issue of increasing interest in fishway science. Despite its potential for aiding fish passage, few studies are available on retrofitting of pool-and-weir Fishways by adding boulders at the bottom of each pool of these facilities. The aim of this study was to assess the performance of a full-scale retrofitted pool-and-weir fishway model with boulders placed at the bottom of each pool, to enhance passage of a cyprinid species, the Iberian barbel ( Luciobarbus bocagei ), which was considered as a representative of medium-sized benthic potamodromous cyprinids in Iberia and Western Europe. Particular attention was given to testing the effects of boulder density and fishway discharge on passage success and fish transit time, both of which affect fish passage efficiency. Although no significant difference in passage success was detected between boulder spacings (mean proportion for high density: 35% success; mean proportion for low density: 40% success), increased flows (62.7 l/s) induced a higher mean proportion ( P P
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pool type Fishways two different morpho ecological cyprinid species facing plunging and streaming flows
PLOS ONE, 2013Co-Authors: Paulo Branco, C Katopodis, Jose Maria Santos, Antonio N Pinheiro, Maria Teresa FerreiraAbstract:Fish are particularly sensitive to connectivity loss as their ability to reach spawning grounds is seriously affected. The most common way to circumvent a barrier to longitudinal connectivity, and to mitigate its impacts, is to implement a fish passage device. However, these structures are often non-effective for species with different morphological and ecological characteristics so there is a need to determine optimum dimensioning values and hydraulic parameters. The aim of this work is to study the behaviour and performance of two species with different ecological characteristics (Iberian barbel Luciobarbus bocagei–bottom oriented, and Iberian chub Squalius pyrenaicus–water column) in a full-scale experimental pool-type fishway that offers two different flow regimes–plunging and streaming. Results showed that both species passed through the surface notch more readily during streaming flow than during plunging flow. The surface oriented species used the surface notch more readily in streaming flow, and both species were more successful in moving upstream in streaming flow than in plunging flow. Streaming flow enhances upstream movement of both species, and seems the most suitable for Fishways in river systems where a wide range of fish morpho-ecological traits are found.
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the development of fish passage research in a historical context
Ecological Engineering, 2012Co-Authors: C Katopodis, John G WilliamsAbstract:Abstract For centuries, humankind has constructed dams on rivers to control flooding, provide for irrigation and utilize potential energy for power, but generally dams had no or little provision for fish passage. Thus, they often blocked or impeded fish migrations. Empirical observations and “trial and error” approaches that characterized historical efforts to develop passage systems for upstream migrating fish often did not work. The first concerted efforts to develop scientifically based Fishways for upstream migrant fish began in the early 1900s in Europe with field and laboratory testing of different fishway designs. These were followed by extensive efforts beginning in the 1940s in North America. Scientifically based testing of configurations for Fishways for downstream migrant fish began in the 1950s. Nearly all early efforts were directed at salmonid species, with smaller efforts on shad. Recent species at risk legislation in the U.S.A., Canada, and Europe places renewed emphasis on fish passage for all migratory species, and efforts have also begun to develop successful passage strategies for migratory species in other countries worldwide. This has led to renewed efforts to develop effective passage systems and to try creative solutions using natural materials in addition to concrete or metal used in standard technical Fishways. Regardless of the type of structures built, history has shown that the most effective means to develop successful installations has occurred when engineers and biologists worked together systematically to design passage structures based on the ability and willingness of fish to seek and accept the hydraulic conditions presented to them.
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ecohydraulics of pool type Fishways getting past the barriers
Ecological Engineering, 2012Co-Authors: Jose Maria Santos, C Katopodis, Antonio N Pinheiro, Ana T Silva, Paulo Pinheiro, Jorge Bochechas, Maria Teresa FerreiraAbstract:Abstract The construction of pool-type Fishways has greatly increased in recent years in response to widespread river fragmentation by man-made structures. However, the performance of such facilities has often been questioned, particularly for non-salmonid fish fauna, which are frequently the predominant group of species found in rivers. This study presents the main findings from field and experimental research conducted over the last 10 years on pool-type Fishways in Portugal. Specific goals were: (i) to catalogue and evaluate the effectiveness of pool-type Fishways built at small hydropower plants (SHP); (ii) to assess passage patterns of migrant fish populations through a “highly suitable” facility; (iii) to assess fish use for submerged orifices and surface notches under different flow regimes in experimental conditions and (iv) to determine the effect of hydraulic parameters on upstream movements of fish within these Fishways. More than half (n = 19, 51%) of the visited Fishways were considered to be unsuitable for the target potamodromous species. Seasonal movements peaked in the spring (>70%) and occurred independently of time of day. Laboratory experiments showed a significantly greater proportion of movements occurring through submerged orifices rather than surface notches. Of all the analyzed hydraulic parameters, the Reynolds shear stress was the one that most influenced fish movements within the Fishways investigated. The results of this study provide new information and insights that could have important implications on the design of future Fishways, particularly for larger potamodromous cyprinids.
Martyn C Lucas - One of the best experts on this subject based on the ideXlab platform.
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evaluating the effectiveness of a larinier super active baffle fish pass for european river lamprey lampetra fluviatilis before and after modification with wall mounted studded tiles
Ecological Engineering, 2016Co-Authors: Jeroen S Tummers, Emily Winter, Sergio Silva, Pat Obrien, Minho Jang, Martyn C LucasAbstract:To help achieve effective longitudinal river connectivity, evaluation of the efficacy of fishway use by upstream-migrating fishes is needed. Larinier super active baffle (SAB) Fishways are relatively cheap retrofit fish passes, suitable for low-head barriers, widespread in Europe and the most commonly fitted technical pass in Britain. Their suitability for non-salmonids, however, is poorly quantified. The efficacy of a 15% gradient SAB fishway and effects of flow regime and water temperature were tested for European river lamprey (Lampetra fluviatilis) using passive integrated transponder (PIT) and acoustic telemetry at a Crump weir on the River Derwent, Northeast England. In migration season 2013–14, over a wide range of flows, 90.1% of 350 tagged lamprey entered the fishway. One fish (0.3%) of those that entered the pass ascended successfully, even though measured water velocity was within laboratory-measured performance conditions for this species. Of 29 acoustic-tagged lamprey that visited the weir over the same period, four (13.8%) ascended it directly, during elevated flows. These data suggest that high turbulence and/or the physical characteristics of baffles may inhibit lamprey ascent of the pass. In migration season 2014–15, we tested the effect of adding studded modular plastic tiles adjacent to the fishway wall, employing PIT antennas separately interrogating the entrance and exit of each of the main fishway and tile routes. 85.8% (169) of 197 tagged lamprey entered the fishway, of which 72/169 (42.6%) entered the tile entrance. Passage efficiency of entrants was 7.1% (12/169), all of which used the tiled route. Reduced local flow velocity in combination with increased availability of resting habitat within the tiles may have facilitated increased passage. Although fishway passage efficiency increased after placement of the modular tiles, it remained half that measured for direct weir passage, both of which are inadequate for connectivity restoration. Quantitative tests of studded tiles placed on the sloping downstream weir face by comparison to control conditions may be more effective and are needed. This study demonstrates the importance of carrying out full-scale field tests to supplement possible solutions developed under laboratory conditions.
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extreme inefficiency of two conventional technical Fishways used by european river lamprey lampetra fluviatilis
Ecological Engineering, 2013Co-Authors: William L Foulds, Martyn C LucasAbstract:In recent years, Fishways have increasingly been designed and installed with the intention to not only provide economically important fishes, such as salmonids, with free passage at barriers, but also for other elements of the migratory fish community. However, in Europe and North America, large numbers of conventional technical Fishways exist, for which the efficacy and suitability for non-salmonid species is often inadequately known. Using passive integrated transponder (PIT) telemetry, this study evaluated the efficacy of two such conventional, technical Fishways (pool and weir and plain Denil baffle) located on the Yorkshire River Derwent, north-east England, for the threatened anadromous European river lamprey Lampetra fluviatilis, an anguilliform swimmer, over the upstream migration and spawning seasons. For lamprey that entered the Fishways, 0.0% and 5.0% passage efficiencies were recorded for Denil (n = 1) and pool and weir (n = 1) Fishways, respectively, over the entire study period. The pool and weir fishway exhibited poor attraction efficiency (42.6%) compared to the Denil fishway (91.8%), and lamprey took significantly longer to locate the pool and weir fishway, probably as a result of ineffective attraction flow. Most lamprey detected at the fishway entrances were recorded within 24 h of release and returned mostly during high flow events on up to 12 separate dates over a 150 day period. Under these conditions, these Fishways were unsuitable for river lamprey. Emphasis is placed upon the increased need for a thorough consideration of the entire migratory fish community during the inception of fishway designs, and that post-construction, strategic evaluation of Fishways should be actively supported and encouraged to advance the provision of effective multi-species Fishways.
Alex Haro - One of the best experts on this subject based on the ideXlab platform.
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migratory behavior of adult sea lamprey and cumulative passage performance through four Fishways
Canadian Journal of Fisheries and Aquatic Sciences, 2017Co-Authors: Theodore Castrosantos, Xiaotao Shi, Alex HaroAbstract:This article describes a study of PIT-tagged sea lamprey (Petromyzon marinus) ascending four Fishways comprising three designs at two dams on the Connecticut River, USA. Migration between dams was rapid (median migration rate = 23 km·day−1). Movement through the Fishways was much slower, however (median = 0.02–0.33 km·day−1). Overall delay at dams was substantial (median = 13.6–14.6 days); many fish failed to pass (percent passage ranged from 29% to 55%, depending on fishway), and repeated passage attempts compounded delay for both passers and failers. Cox regression revealed that fishway entry rates were influenced by flow, temperature, and diel cycle, with most lampreys entering at night and at elevated flows, but with no apparent effect of sex or length. Overall delay was influenced by slow movement through the Fishways, but repeated failures were the primary factor determining delay. These data suggest that although some lamprey were able to pass Fishways, they did so with difficulty, and delays incur...
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evaluation of nature like and technical Fishways for the passage of alewives at two coastal streams in new england
Transactions of The American Fisheries Society, 2012Co-Authors: A Franklin, Theodore Castrosantos, Alex Haro, John NoreikaAbstract:Abstract Nature-like Fishways have been designed with the intent to reconnect river corridors and provide passage for all species occurring in a system. The approach is gaining popularity both in Europe and North America, but performance of these designs has not been quantitatively evaluated in a field setting for any North American species. Two nature-like Fishways and three technical Fishways in New England were evaluated for passage of anadromous adult alewives Alosa pseudoharengus by using passive integrated transponder (PIT) telemetry. A perturbation boulder rock ramp (32 m long; 4.2% slope) constructed in Town Brook (Plymouth, Massachusetts) passed 94% of the fish that made passage attempts, with most fish ascending the ramp in less than 22 min. In the East River (Guilford, Connecticut), a step-pool bypass design (48 m long; 7.1% slope) passed only 40% of attempting fish, with a median transit time of 75 min. In Town Brook, a technical pool-and-weir fishway (14 m long; 14.3% slope) exhibited poor en...
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performance of fish passage structures at upstream barriers to migration
River Research and Applications, 2012Co-Authors: C M Bunt, Theodore Castrosantos, Alex HaroAbstract:Attraction and passage efficiency were reviewed and compared from 19 monitoring studies that produced data for evaluations of poolâandâweir, Denil, verticalâslot and natureâlike Fishways. Data from 26 species of anadromous and potamodromous fishes from six countries were separated by year and taxonomic family into a matrix with 101 records. Attraction performance was highly variable for the following fishway structures: poolâandâweir (attraction rangeâ=â29â100%, meanâ=â77%, medianâ=â81%), verticalâslot (attraction rangeâ=â0â100%, meanâ=â63%, medianâ=â80%), Denil (attraction rangeâ=â21â100%, meanâ=â61%, medianâ=â57%) and natureâlike (attraction rangeâ=â0â100%, meanâ=â48%, medianâ=â50%). Mean passage efficiency was inversely related to mean attraction efficiency by fishway structure type, with the highest passage for natureâlike Fishways (rangeâ=â0â100%, meanâ=â70%, medianâ=â86%), followed by Denil (rangeâ=â0â97%, meanâ=â51%, medianâ=â38%), verticalâslot (rangeâ=â0â100%, meanâ=â45%, medianâ=â43%) and poolâandâweir (rangeâ=â0â100%, meanâ=â40%, medianâ=â34%). Principal components analysis and logistic regression modelling indicated that variation in fish attraction was driven by biological characteristics of the fish that were studied, whereas variation in fish passage was related to fishway type, slope and elevation change. This metaâanalysis revealed that the species of fish monitored and structural design of the Fishways have strong implications for both attraction and passage performance, and in most cases, existing data are not sufficient to support design recommendations. Many more fishway evaluations are needed over a range of species, fishway types and configurations to characterize, to optimize and to design new Fishways. Furthermore, these studies must be performed in a consistent manner to identify the relative contributions of fish attraction and passage to overall fishway performance at each site.
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effect of slope and headpond on passage of american shad and blueback herring through simple denil and deepened alaska steeppass Fishways
North American Journal of Fisheries Management, 1999Co-Authors: Alex Haro, Mufeed Odeh, Theodore Castrosantos, John NoreikaAbstract:Abstract Passage and transit time of adult upstream-migrant American shad Alosa sapidissima and blueback herring A. aestivalis were investigated in standard Denil and Alaska steeppass Fishways with variable slope and headpond under semicontrolled conditions. Percent of American shad passed per unit time (percent passage) increased with temperature, while time required to ascend from the fishway entrance to the exit (transit time) decreased with increasing temperature for both species. Increasing fishway slope decreased percent passage of American shad, regardless of fishway type. Higher fishway slope decreased percent passage of blueback herring in the steeppass fishway only. Low headpond enhanced percent passage of American shad in the Denil fishway, but decreased percent passage of American shad in the steeppass fishway. Headpond level had no effect on percent passage of blueback herring in either fishway. Because headpond level in the steeppass fishway affected percent passage of American shad but not ...
Theodore Castrosantos - One of the best experts on this subject based on the ideXlab platform.
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migratory behavior of adult sea lamprey and cumulative passage performance through four Fishways
Canadian Journal of Fisheries and Aquatic Sciences, 2017Co-Authors: Theodore Castrosantos, Xiaotao Shi, Alex HaroAbstract:This article describes a study of PIT-tagged sea lamprey (Petromyzon marinus) ascending four Fishways comprising three designs at two dams on the Connecticut River, USA. Migration between dams was rapid (median migration rate = 23 km·day−1). Movement through the Fishways was much slower, however (median = 0.02–0.33 km·day−1). Overall delay at dams was substantial (median = 13.6–14.6 days); many fish failed to pass (percent passage ranged from 29% to 55%, depending on fishway), and repeated passage attempts compounded delay for both passers and failers. Cox regression revealed that fishway entry rates were influenced by flow, temperature, and diel cycle, with most lampreys entering at night and at elevated flows, but with no apparent effect of sex or length. Overall delay was influenced by slow movement through the Fishways, but repeated failures were the primary factor determining delay. These data suggest that although some lamprey were able to pass Fishways, they did so with difficulty, and delays incur...
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ascent ability of brown trout salmo trutta and two iberian cyprinids iberian barbel luciobarbus bocagei and northern straight mouth nase pseudochondrostoma duriense in a vertical slot fishway
Knowledge and Management of Aquatic Ecosystems, 2016Co-Authors: Fco Javier Sanzronda, Juan Francisco Fuentesperez, F J Bravocordoba, Theodore CastrosantosAbstract:Passage performance of brown trout (Salmo trutta ), Iberian barbel (Luciobarbus bocagei ), and northern straight-mouth nase (Pseudochondrostoma duriense) was investigated in a vertical slot fishway in the Porma River (Duero River basin, Spain) using PIT telemetry. We analysed the effects of different fishway discharges on motivation and passage success. Both cyprinid species ascended the fishway easily, performing better than the trout despite their theoretically weaker swimming performance. Fishway discharge affected fish motivation although it did not clearly influence passage success. Observed results can guide design and operation criteria of vertical slot Fishways for native Iberian fish.
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evaluation of nature like and technical Fishways for the passage of alewives at two coastal streams in new england
Transactions of The American Fisheries Society, 2012Co-Authors: A Franklin, Theodore Castrosantos, Alex Haro, John NoreikaAbstract:Abstract Nature-like Fishways have been designed with the intent to reconnect river corridors and provide passage for all species occurring in a system. The approach is gaining popularity both in Europe and North America, but performance of these designs has not been quantitatively evaluated in a field setting for any North American species. Two nature-like Fishways and three technical Fishways in New England were evaluated for passage of anadromous adult alewives Alosa pseudoharengus by using passive integrated transponder (PIT) telemetry. A perturbation boulder rock ramp (32 m long; 4.2% slope) constructed in Town Brook (Plymouth, Massachusetts) passed 94% of the fish that made passage attempts, with most fish ascending the ramp in less than 22 min. In the East River (Guilford, Connecticut), a step-pool bypass design (48 m long; 7.1% slope) passed only 40% of attempting fish, with a median transit time of 75 min. In Town Brook, a technical pool-and-weir fishway (14 m long; 14.3% slope) exhibited poor en...
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performance of fish passage structures at upstream barriers to migration
River Research and Applications, 2012Co-Authors: C M Bunt, Theodore Castrosantos, Alex HaroAbstract:Attraction and passage efficiency were reviewed and compared from 19 monitoring studies that produced data for evaluations of poolâandâweir, Denil, verticalâslot and natureâlike Fishways. Data from 26 species of anadromous and potamodromous fishes from six countries were separated by year and taxonomic family into a matrix with 101 records. Attraction performance was highly variable for the following fishway structures: poolâandâweir (attraction rangeâ=â29â100%, meanâ=â77%, medianâ=â81%), verticalâslot (attraction rangeâ=â0â100%, meanâ=â63%, medianâ=â80%), Denil (attraction rangeâ=â21â100%, meanâ=â61%, medianâ=â57%) and natureâlike (attraction rangeâ=â0â100%, meanâ=â48%, medianâ=â50%). Mean passage efficiency was inversely related to mean attraction efficiency by fishway structure type, with the highest passage for natureâlike Fishways (rangeâ=â0â100%, meanâ=â70%, medianâ=â86%), followed by Denil (rangeâ=â0â97%, meanâ=â51%, medianâ=â38%), verticalâslot (rangeâ=â0â100%, meanâ=â45%, medianâ=â43%) and poolâandâweir (rangeâ=â0â100%, meanâ=â40%, medianâ=â34%). Principal components analysis and logistic regression modelling indicated that variation in fish attraction was driven by biological characteristics of the fish that were studied, whereas variation in fish passage was related to fishway type, slope and elevation change. This metaâanalysis revealed that the species of fish monitored and structural design of the Fishways have strong implications for both attraction and passage performance, and in most cases, existing data are not sufficient to support design recommendations. Many more fishway evaluations are needed over a range of species, fishway types and configurations to characterize, to optimize and to design new Fishways. Furthermore, these studies must be performed in a consistent manner to identify the relative contributions of fish attraction and passage to overall fishway performance at each site.
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effect of slope and headpond on passage of american shad and blueback herring through simple denil and deepened alaska steeppass Fishways
North American Journal of Fisheries Management, 1999Co-Authors: Alex Haro, Mufeed Odeh, Theodore Castrosantos, John NoreikaAbstract:Abstract Passage and transit time of adult upstream-migrant American shad Alosa sapidissima and blueback herring A. aestivalis were investigated in standard Denil and Alaska steeppass Fishways with variable slope and headpond under semicontrolled conditions. Percent of American shad passed per unit time (percent passage) increased with temperature, while time required to ascend from the fishway entrance to the exit (transit time) decreased with increasing temperature for both species. Increasing fishway slope decreased percent passage of American shad, regardless of fishway type. Higher fishway slope decreased percent passage of blueback herring in the steeppass fishway only. Low headpond enhanced percent passage of American shad in the Denil fishway, but decreased percent passage of American shad in the steeppass fishway. Headpond level had no effect on percent passage of blueback herring in either fishway. Because headpond level in the steeppass fishway affected percent passage of American shad but not ...
Mary L. Moser - One of the best experts on this subject based on the ideXlab platform.
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Providing refuges for adult Pacific lamprey Entosphenus tridentatus inside Fishways
Aquaculture and Fisheries, 2021Co-Authors: Mary L. Moser, Matthew L. Keefer, Kinsey E. Frick, Christopher C. Caudill, Stephen C. Corbett, Sean C. TackleyAbstract:Abstract Fishways at hydroelectric dams are unnatural environments that typically present fish with channels of uniform depth, variable water velocity, and lack of cover. Fish retention and overall passage success may be improved by providing rest and sheltering areas inside Fishways. We examined adult Pacific lamprey Entosphenus tridentatus use of two specially designed fishway refuges at Bonneville Dam on the Columbia River (northwestern USA). These relatively small boxes (1.1 m × 0.4 m × 0.2 m) provided low-velocity, dark refuge from predation for Pacific lamprey, a largely nocturnal species. Refuge boxes were equipped with antennas to detect entry of lamprey tagged with passive integrated transponder (PIT) tags. We PIT tagged and released 3,247 lamprey, including 599 that were double-tagged with a PIT and a radio transmitter, over three study years (2012–2014). In each year, PIT-tagged lamprey detected at nearby fishway exits had used a refuge: 12% in 2012, 28% in 2013, and 36% in 2014. Median residence time of PIT-tagged lamprey in the refuges for each year was 20.3 h, 16.6 h, and 13.1 h. Lamprey entrance into refuges peaked at 0300–0500 PDT, and they typically exited at around 2000 PDT, suggesting that refuges primarily functioned as shelter from daylight. Probability of refuge use increased with a morphological indicator of sexual maturity (distance between dorsal fins). In the radio-tagged group, refuge users were equally likely to pass Bonneville Dam as non-users. However, refuge users were less likely than non-users to be detected at sites upstream from the dam, perhaps owing to their maturation status or longer mean passage time through our study area (2.0 vs. 0.6 d for non-users). Refuges show promise for improving fish retention in Fishways, particularly for nocturnal and/or small-bodied species that seek shelter from light or predation.
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testing adult pacific lamprey performance at structural challenges in Fishways
North American Journal of Fisheries Management, 2010Co-Authors: Matthew L. Keefer, William R Daigle, Christopher A Peery, Howard T Pennington, Steven R Lee, Mary L. MoserAbstract:Abstract Adult Pacific lampreys Lampetra tridentata migrate through areas of difficult passage and high water velocity by attaching their oral discs to substrate and then releasing and bursting upstream. In Fishways at dams, this burst-and-attach behavior can be ineffective, particularly where suitable attachment surfaces are unavailable. We used an experimental fishway to test performance of adult Pacific lampreys when confronted with a series of structural challenges. These included vertical steps near fishway weir orifices, squared versus rounded orifice entrances, and floor-mounted metal grates. All experimental challenges simulated common existing structures in weir-and-orifice Fishways at Columbia and Snake River dams. Most experiments were paired with field evaluations of radio-tagged Pacific lampreys or video observations of untagged individuals in situ. Field and experimental results consistently indicated that the structural challenges reduced passage efficiency and lengthened passage times. Imp...
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Use of an extensive radio receiver network to document Pacific lamprey (Lampetra tridentata) entrance efficiency at Fishways in the Lower Columbia River, USA
Hydrobiologia, 2002Co-Authors: Mary L. Moser, Alicia L. Matter, Lowell C. Stuehrenberg, Ted C. BjornnAbstract:We used an extensive network of more than 170 radio receiving stations to document fine-scale passage efficiency of adult anadromous Pacific lamprey at Bonneville and The Dalles Dams in the lower Columbia River in the northwestern U.S.A. Each spring from 1997 to 2000, we released 197–299 lamprey with surgically implanted radio transmitters. Unique transmitter codes and the date and time of reception at each antenna site were downloaded electronically, and initial processing was conducted to eliminate false positive signals. The resulting large Oracle database was analyzed using an ArcView-based coding protocol. Underwater antennas positioned outside the fishway entrances detected lamprey approaches, and antennas positioned immediately inside the entrances indicated successful entries. Entrance efficiency (the number of lamprey that successfully entered a fishway divided by the number that approached that fishway) was compared for different types of entrances (main entrances versus orifice entrances) and entrance locations (powerhouse versus spillway). Lamprey used orifice-type entrances less frequently than main entrances, and passage success was generally low (< 50%) at all entrances to Fishways at Bonneville Dam (the lowest dam in the system). Lamprey activity at the entrances was highest at night, and entrance success was significantly higher at The Dalles Dam (the next dam upstream from Bonneville Dam) than at Bonneville Dam. In 1999 and 2000, construction modifications were made to Bonneville Dam spillway entrances, and water velocity at these entrances was reduced at night. Modifications to increase lamprey attachment at the entrances improved lamprey entrance efficiency, but entrance efficiency during reduced velocity tests was not significantly higher than during control conditions.