Effects of nutrient enrichment on channel catfish growth and consumption in Mount Storm Lake, West Virginia

With the objective of augmenting fish production in Mount Storm Lake, Virginia Electric and Power Company initiated a programme of phosphorus addition to increase primary production, and ultimately, channel catfish ( Ictaturus punctatus ) growth in the 486 ha cooling reservoir. We simulated channel catfish growth dynamics using two bioenergetics modelling scenarios: (i) effects of average reservoir temperature on growth, conversion efficiency and consumption; and (ii) effects of reservoir enrichment on growth, which is simulated by increasing feeding rates. During 1991–1993, fish were sampled monthly, but sampling was increased to every 2 weeks during the peak growing season (June–September). Most of the channel catfish collected were aged 0 year and aged 1 year with rapid annual growth rates ranging from 9.0 to 13.7 J/g. We found many age 1 250–300 mm catfish, but few beyond this size. Conversion efficiency (joules gained/joules consumed) was low at approximately 18–19%. High algae consumption (40%) was evident, but consumption of zooplankton and Asiatic clam ( Corbicula sp.) increased over the study. Simulated increased feeding rates showed that channel catfish were food limited in summer and fall (July–December). Weight gains with 5 and 10% feeding increases were 6–13% and 18–38%, respectively, from the baseline. Catfish of all sizes should benefit from phosphorus additions.     

Applicability of the flood‐pulse concept in a temperate floodplain river ecosystem: thermal and temporal components

Annual growth increments were calculated for blue catfish (Ictalurus furcatus) and flathead catfish (Pylodictis olivaris) from the lower Mississippi River (LMR) to assess hypothesized relationships between fish growth and floodplain inundation as predicted by the Flood‐Pulse Concept. Variation in catfish growth increment was high for all age classes of both species, and growth increments were not consistently related to various measures of floodplain inundation. However, relationships became stronger, and usually direct, when water temperature was integrated with area and duration of floodplain inundation. Relationships were significant for four of six age classes for blue catfish, a species known to utilize floodplain habitats. Though similar in direction, relationships were weaker for flathead catfish, which is considered a more riverine species. Our results indicate the Flood‐Pulse Concept applies more strongly to temperate floodplain‐river ecosystems when thermal aspects of flood pulses are considered. We recommend that future management of the LMR should consider ways to ‘recouple’ the annual flood and thermal cycles. An adaptive management approach will allow further determination of important processes affecting fisheries production in the LMR. Copyright © 2006 John Wiley & Sons, Ltd.     

Fatty Acid Profiles Distinguish Channel Catfish from Three Reaches of the Lower Kaskaskia River and its Floodplain Lakes

Despite the increasing use of fatty acids (FAs) as biomarkers in aquatic food web analysis, little information is available regarding differences in FA profiles of fish among habitat types in river–floodplain ecosystems. The objectives of this study were to (i) test whether the FA profiles of channel catfish (Ictalurus punctatus) differed among three reaches of the lower Kaskaskia River and its floodplain lakes, and (ii) to compare FA profiles among muscle, liver, and adipose fin tissues collected from these fish. Profiles differed significantly among sites, especially between upper and lower river sites, and between river channel and oxbow lake sites, suggesting differences in FA availability for channel catfish occupying different habitats and river reaches in the Kaskaskia River system. Specifically, the essential FAs 18:2n‐6 and 18:3n‐3 increased in catfish tissues from upstream to downstream reaches, which could reflect increased floodplain connectivity and decreasing impoundment effects downstream. Ratios of n‐3 to n‐6 FAs were higher in fish from oxbow lakes, perhaps suggesting increased use of autochthonous production in the floodplain relative to the main river channel. Muscle and adipose fin FA profiles exhibited similar location‐related trends, whereas liver FA profiles were markedly different from the other tissue types. These results suggest that adipose fin tissue samples may be a viable, less‐invasive alternative to muscle tissue for analysis of FA profiles in channel catfish. Our study supports the use of tissue FA profiles in identifying habitat utilization by channel catfish, and perhaps habitat‐specific energy contributions to riverine consumers. Furthermore, our work highlights floodplain habitat as a potential source of essential n‐3 FA and the associated importance of maintaining river–floodplain connectivity to support aquatic food webs. Copyright © 2014 John Wiley & Sons, Ltd.     

Documentation of the temporal and spatial patterns of pimelodidae catfish spawning and larvae dispersion in the madre de Dios River (Peru): Insights for conservation in the Andean‐Amazon headwaters

Catfishes (Siluriformes: Pimelodidae) in the Amazon River Basin serve important ecological and economic roles in structuring foodwebs, transferring nutrients and providing food resources for human populations. Large‐scale developments such as construction of the Interoceanic Highway and associated proposed hydroelectric facilities could lead to alterations in river hydrology and aquatic ecosystems within Amazon headwater regions. We assessed temporal and spatial distribution patterns of catfish larvae to determine spawning location (highlands or lowlands) and larval drift patterns associated with rainfall events in the Andean‐Amazon headwaters. We found significant differences in larval fish catch between transects with highest catches occurring in the Madre de Dios River, suggesting that the primary spawning habitats for these catfishes were in regions upstream of our sampling region within the Peruvian Andes. Highest larval catfish catches generally occurred near shore and in association with seasonal pulses in river flow. Based on our observations, we propose that this section of the Madre de Dios River is near the first identified spawning area for Pimelodidae species in the Peruvian Andes, and from this river reach larvae are transported downstream with each seasonal flood event with peak transport generally occurring in October, November and December. This research documents the important role the Madre de Dios Basin plays as spawning habitat for a key fish family in the Amazon River by serving as a corridor both for adult catfish spawning migrations and downstream larval fish transport. Given the critical role these catfishes play in structuring aquatic ecosystems in the Andean‐Amazon region, their importance as a food resource for local people, and increasing threats to this riverine ecosystem associated with dam construction and channel modification, it is important to maintain and protect natural hydrologic conditions in the Madre de Dios to minimize losses of these ecosystem goods and services. Copyright © 2010 John Wiley & Sons, Ltd.     

INTRA‐ANNUAL VARIATION IN RIVER–RESERVOIR INTERFACE FISH ASSEMBLAGES: IMPLICATIONS FOR FISH CONSERVATION AND MANAGEMENT IN REGULATED RIVERS

While much is known about the fish assemblages, habitats, and ecology of rivers and reservoirs, there has been limited study of the fish assemblages in transitional habitats between these lotic and lentic habitats. Data about these river–reservoir interface (RRI) fish assemblages are needed to guide integrated management efforts of river–reservoir ecosystems. The aim of these efforts is to recommend flows for natural river function, conserve native riverine fish assemblages, and maintain reservoir sport fisheries. We used a multigear approach to assess the fish assemblages of four RRIs in the Colorado River Basin, Texas. In addition to characterizing RRI fish assemblages using species richness and evenness metrics, and habitat‐use guilds, we used a multivariate approach to evaluate intra‐annual shifts in species composition and abundance. All RRIs had high species richness and evenness values and included both macrohabitat generalist and fluvial species. RRIs also contained high proportions of the fish species available within each river–reservoir ecosystem, ranging from 55% to 80%. Observed intra‐annual shifts in RRI fish assemblages resulted from changes in abundance of dominant species rather than changes in species composition, with abundance of most species increasing from early spring to summer. Fish species responsible for intra‐annual shifts included mostly floodplain and migratory species, suggesting that species both used littoral habitats within RRIs and migrated through RRIs to river and reservoir habitats. The diversity of fishes found within RRIs highlights the importance of including these areas in future conservation and management efforts of river–reservoir ecosystems. Copyright © 2013 John Wiley & Sons, Ltd.     

Environmental impacts of integrated fisheries development in the Bicol river basin,the Philippines

This article is based on a study conducted from March 15 to August 15, 1983 at the proposed Naga‐Calabanga Integrated Fisheries Development Project in the Bicol region, the Philippines. Baseline studies were conducted on all environmental parameters and impact predictions were made. The Bicol River, the main source of water supply for the proposed fishery estate was found to be polluted in terms of total solids; BOD, phenol, cyanide and bacteria, but these would not be a limiting criteria for fish production since milkfish have a wide tolerance for physical, chemical and biological conditions. The project area was marginal with respect to agricultural activity. Conversion of the site to the proposed fishery project would cause some localized adverse ecological impacts but the net impact would be beneficial and enhance estuarine environment. Some adverse impacts include barriers to migratory fish such as mullet, arid catfish and shrimps, deterioration of water quality downstream, probable increase of vector diseases, destruction of minor agricultural crops and vegetation and change of landform (from terrestrial ecosystems to aquatic ecosystems). Positive impacts include increased fish productivity, job opportunities, revenues, increased wetlands and improvement of health and nutrition. Thus, the aims and purpose of the project shall be achieved without unduly causing much adverse ecological impact on the environment.     

Distribution,movements and habitat use of channel catfish in a river with multiple low‐head dams

Channel catfish Ictalurus punctatus is a highly mobile species and is known to make extensive seasonal movements in lotic systems. Dams have been suggested to detrimentally affect this species, although abundant channel catfish populations are known to occur in many fragmented rivers. To examine factors that allow channel catfish to persist in impounded rivers, we assessed relative abundance of channel catfish in three impounded and three flowing sites of the Fox River, Illinois, USA. Radiotelemetry was used to determine movement and habitat use patterns of channel catfish among flowing and impounded areas. Relative abundance of channel catfish was consistently higher at flowing sites than at impounded sites during summer. Several radio‐tagged channel catfish moved downstream into impounded areas in fall, and all tagged individuals were found in impounded areas during winter. The majority of tagged channel catfish moved upstream into flowing areas during spring. Channel catfish used a wide range of depths (0.28–2.60 m), and were always found in current velocities less than 0.50 m s^?1. They selected most strongly for coarse substrates, but were infrequently found near cover. Although low‐head dams restrict the movements of channel catfish, impounded areas appear to provide overwintering habitats that may eliminate the need for seasonal long‐distance movements. Small run‐of‐river impoundments, however, may contain unsuitable conditions for channel catfish during other seasons. Copyright © 2010 John Wiley & Sons, Ltd.     

Spatial and temporal distribution of ichthyoplankton during an unusual period of low flow in a tributary of the São Francisco River,Brazil

Flow‐dependent fish specialists require specific conditions for reproduction, so the success and reproductive intensity of these animals are determined by the flood regime. Thus, this study investigated the spatial and temporal reproductive patterns of fish, especially migratory Prochilodus species (flow‐dependent specialists) in an unusual period of low flow in the Pará River sub‐basin, one of the main tributaries of the upper São Francisco River. For this, ichthyoplankton collections were carried out between November 2013 and February 2014. Data were analysed considering the spatial and temporal variations in density of eggs and larvae for the upper, middle, and lower portions of the Pará River sub‐basin, and correlating this to some environmental variables. The results showed that the small headwater stretch of the Pará River is one relevant spawning area for migratory fish species. However, this area is isolated by the Cajuru reservoir, which makes it uncertain the recruitment of these embryos, due to interruption of natural drift between spawning/nursery areas caused for reservoirs. Larvae of newly hatched migratory species found in tributaries of the lower Pará River sub‐basin also indicate these species use these tributaries as spawning grounds and migratory routes. The period in which the research was conducted represented the most atypical low flow, one in the last 75 years, resulting in the low variability in the environmental parameters. Although few parameters increased briefly in this low flow period influenced by greater rainfall in December, this precipitation was possibly responsible for the final gonadal maturation and spawning of migratory species.     

Population characteristics and potential factors influencing recruitment variability of blue catfish,channel catfish and flathead catfish in Thunderbird Reservoir,Oklahoma

Blue catfish (Ictalurus furcatus), channel catfish (Ictalurus punctatus) and flathead catfish (Pylodictis olivaris) are popular sport fishes throughout North America, and are therefore intensively managed by some natural resource agencies. Although catfish fisheries rely on sufficient natural reproduction and recruitment to sustain these populations, few studies have evaluated the variables affecting catfish recruitment. Thus, the objectives of this study were to describe population characteristics (age, size structure, condition, growth, mortality and recruitment) of blue catfish, channel catfish and flathead catfish in Thunderbird Reservoir, Oklahoma, and evaluate the effects of hydrology, water quality and temperature on year-class strength. During 2017 and 2018, 235 blue catfish, 194 channel catfish and 120 flathead catfish were collected and aged using otoliths. In general, these catfish species in Thunderbird Reservoir were slow growing, long-lived, had low mortality rates and experienced variable recruitment. Blue catfish recruitment was lower in years with higher average January air temperatures. Channel catfish recruitment was higher in years with increased average annual and spring/summer exchange rate and increased spring/summer average reservoir water volume (ha-m). Conversely, higher annual average total hardness (mg/L) resulted in decreased recruitment for channel catfish. Flathead catfish recruitment exhibited a minimal negative impact with increased annual reservoir volume (ha-m). The present study is among the first to describe potential variables influencing year-class formation of blue catfish, channel catfish and flathead catfish in reservoirs. Although the variables found to influence catfish recruitment are outside the control of fisheries managers, biologists should promote downstream angling opportunities for blue catfish that escape during reservoir water release events and stock channel catfish in systems with consistently high total water hardness in order to maximize fishing opportunities. Further, they can use the results of this study to manage angler expectations following periods of low recruitment.     

Influence of artificial reefs on fish assemblage of the Barra Bonita Reservoir (São Paulo, Brazil)

This paper deals with the effects of introduced artificial reefs on the diversity of freshwater fish communities in lentic and lotic zones of a very impacted river in southeastern Brazil. To accomplish this goal, artificial reefs were introduced, in December 1997, in the Barra Bonita reservoir and in the lotic zone immediately below the dam. Fish diversity was always higher in the lotic zone than in the reservoir. Accordingly, fish diversity near the artificial reefs was consistently higher than in the control areas. We propose that the higher environmental complexity in the lotic zone, as compared to the reservoir, is incremented in areas where artificial reefs were introduced; also, we present that, in both areas, diversity is mainly affected by the introduction of artificial reefs.     

Fish catch and fishing practices in the Nam Theun 2 Reservoir and watershed (Lao PDR)

A fish catch and fishing practice monitoring survey were conducted from 2008 to 2014 in villages adjacent to the Nam Theun 2 Reservoir and its upstream tributaries. The reservoir fisheries exhibited – the three expected phases following impoundment (i.e. trophic upsurge, trophic depletion and stabilization, respectively). This study focused on assessing fish catches and fishing practices from communities living next to the reservoir, and those living upstream of the reservoir, over these phases, and to identify factors that could influence total fish catch. The fish catch appeared to be higher among communities located next to the reservoir, compared to communities living in upstream areas. Fish catches in the upstream tributaries remained relatively stable after impoundment, with a slight increase in the average catch. The reservoir exhibited a low fish yield, compared to similar reservoirs, which could be linked to its oligotrophic status. The majority of the total catch biomass of the reservoir was comprised primarily of two species (i.e. Oreochromis niloticus; Hampala macrolepidota) since a stabilization of the catches was observed. Reservoir fisheries appeared to be mainly driven by hydrological factors, specifically the influence of the rainy season peak. The results of this study indicated no over‐exploitation of fisheries occurred overall, although the fishery resource is still fragile. Fishing activities are known to occur in protected zones (productive areas with large inundated habitat areas), with higher annual total catch being observed during periods of poor enforcement of these zones. As fisheries have become an important income source for villagers living along the NT2 Reservoir, regulation and adequate management of the reservoir are recommended to maintain the reservoir fisheries as a sustainable activity.     

Evaluation of fish habitat suitability using a coupled ecohydraulic model: Habitat model selection and prediction

The selection of an approach to evaluate habitat suitability for a specific fish or life stage has been a matter of concern in habitat quality modelling studies. This study has taken Jinshaia sinensis, a commercially valuable fish endemic to the Jinsha River, China, as the target fish species. One‐ and two‐dimensional hydrodynamic models were coupled and combined with fish habitat models for a middle reach of the Jinsha River. The resulting ecohydraulic model was used to predict the changes in hydrodynamics and spawning habitat suitability that resulted from the operation of an under‐construction reservoir downstream of the study area. The preference function (product, arithmetic mean, geometric mean, and minimum value) and fuzzy logic habitat evaluation methods were compared to predict the spawning habitat suitability of the fish. The model was validated using the numbers of spawning eggs, and the results show that both the arithmetic mean and fuzzy logic method can be used to predict spawning habitat suitability. The model predictions show that the hydrodynamics of the study area would be altered if the impoundment water level exceeded 969 m. During the spawning season, the spawning habitat suitability would increase from April to early June and has little change from early June to July under the impact of the reservoir impoundment. The optimal river discharge rate for fish spawning is ~3,500 m³/s, and this would not change after the reservoir begins operation. This research can benefit other regions that will be affected by planned dams by predicting the impacts of reservoir operation on fish habitat quality, and the results will help decision makers protect the health of rivers and the overall ecosystem.     

Longitudinal patterns in flathead catfish relative abundance and length at age within a large river: effects of an urban gradient

We investigated the spatial variation of flathead catfish (Pylodictis olivaris) relative abundance and growth in the 274 km long Kansas River to determine if population dynamics of catfish are related to urbanization. Electrofishing was conducted at 462 random sites throughout the river in summer, 2005–2006 to collect fish. Relative abundance of age 1 fish (≤200 mm), subadult (>200–400 mm) and adult fish (>400 mm) ranged from 0.34 to 14.67 fish h^?1, mean length at age 1 was 165 (range: 128–195) mm total length (TL) and mean length at age 3 was 376 mm TL (range: 293–419 mm TL). The proportion of land use within 200 m of the river edge was between 0 and 0.54 urban. River reaches with high relative abundance of age 1 flathead catfish had high relative abundance of subadult and adult catfish. River reaches with fast flathead catfish growth to age 1 had fast growth to age 3. High urban land use and riprap in the riparian area were evident in river reaches near the heavily populated Kansas City and Topeka, Kansas, USA. Reaches with increased number of log jams and islands had decreased riparian agriculture. Areas of low urbanization had faster flathead catfish growth (r = 0.67, p = 0.005). Relative abundance of flathead catfish was higher in more agricultural areas (r = ?0.57, p = 0.02). Changes in land use in riverine environments may alter population dynamics of a fish species within a river. Spatial differences in population dynamics need to be considered when evaluating riverine fish populations. Published in 2008 by John Wiley & Sons, Ltd.     

Catch per Unit Effort and yields as indicators of exploited fish communities: application to two West African reservoirs

Two indicators of fish exploitation, catch per unit effort (CPUE) and yield per unit area, were used with surveys of small‐scale fishery landings to compare two African reservoirs that differ in their level of fish exploitation, being high for Selingue Reservoir and low for Manantali Reservoir, both located in West Africa. The heavy exploitation in Selingue Reservoir induced a decline in catches per fishing trip (9.5 kg trip^?1), whereas the catch remained high at Manantali Reservoir (17.0 kg trip^?1). Moreover, the annual fish yield per unit area was lower for Manantali Reservoir (19 kg ha^?1) than for Selingue Reservoir (79 kg ha^?1). There was no relationship between the Morphoedaphic Index and catches for the two reservoirs. Rather, only the fishing effort and annual water‐level variations defined the reservoir fish yields. Based on the results of the present study, it appears that CPUE and fish yield per unit area represent simple and robust indicators for describing the impacts of fishing intensity in aquatic ecosystems.     

Response of phytoplankton to enrichment from cage fish farm waste in Alicura Reservoir (Patagonia,Argentina)†

Bioassays were undertaken in order to test the response of the natural late‐summer inoculum of the phytoplankton of a Patagonian Reservoir to the additional nutrients generated by the production of salmon in cages. The results are discussed in relation to a 7 year study of the reservoir and the possible directions of trophic development. The main consequences of fish farming activities in Alicura are likely to lead to an increase in both nutrient concentrations, algal density and phytobiomass. The composition of the sediment close to the fish farm is affected. With regard to phytoplankton, we observed changes in species composition and temporal changes in their associations. The additional nutrient sources of fish food and faeces from salmonid production create an internal load that leads to a decrease in the N/P, Si/P and Ca/P ratios of the water column. The trophic level of Alicura Reservoir remains unchanged at present and the impact of fish farming operation remains localized.     

三峡水库运行后库区鱼类资源变化及保护研究

结合历史资料以及现状调查资料,分析了三峡库区形成后,库区江段鱼类资源变化的特征,以及造成库区鱼类资源变动的主要因素,并对库区鱼类所面临的主要生态环境问题进行了辨识。针对水利工程开发对鱼类生境造成的影响,提出了多种生态保护措施,如限制捕捞或全面禁捕、恢复洄游通道、栖息地生境保护等。指出大坝修建所导致的生境破碎化,是改变库区鱼类群落结构的重要因素;而不合理的人工捕捞是导致库区鱼类个体变小的直接原因。     

Addressing uncertainties in the environmental sustainability of limno‐reservoirs: insights from the synthesis of multidisciplinary research

Large reservoirs in the Mediterranean area exhibit a variety of negative impacts resulting from exploitation of their water, many a result of large water‐level fluctuations. Water managers in Spain have implemented various mitigation measures to reduce these negative impacts. One such measure is construction of small dams in the riverine zone of large reservoirs to create a small waterbody with a constant water level (i.e. a ‘limno‐reservoir’) to provide the environmental and recreational services that the main reservoir cannot provide due to water‐level variations. To this end, the Pareja Limno‐reservoir was built in 2006 in a sidearm of the Entrepeñas Reservoir (Guadalajara, central Spain). As its environmental sustainability was not assessed prior to construction, however, there are some uncertainties about the ability of the limno‐reservoir to provide the expected environmental and recreational services. Accordingly, a multidisciplinary study was conducted on the Pareja Limno‐reservoir to shed on its environmental sustainability. This study addressed three relevant issues associated with the limno‐reservoir, focusing on water availability, water quality and the risk of sediment filling. This study reviews the research conducted to date, including an integrative discussion that endeavours to address these issues. The Pareja Limno‐reservoir is currently a successful tourist and recreational aquatic resource. The results of this study, however, reveal its recreational and environmental value may be reduced, especially as a constant water level at the maximum capacity of the limno‐reservoir cannot be guaranteed. The conclusions of this study may be useful for reservoir managers by providing guidelines for assessing the environmental sustainability of limno‐reservoirs.     

乡村振兴战略下的水库移民安置规划探讨

十九大提出的乡村振兴战略对于做好水库移民安置工作具有重大的指导意义。就如何结合乡村振兴战略做好水库移民安置规划进行了探讨。对近年在三峡库区、丹江口库区开展的美丽乡村规划以及亭子口水库、藻渡水库等移民安置规划的实践进行了思考和总结,提出了以总体规划为总纲、产业规划为主线、乡村规划为基础的移民安置规划体系,力求将移民安置和区域发展、乡村振兴统一到一张蓝图上。这种规划方法在近期开展的移民安置规划中进行了运用,取得了较好的效果。     

Spatial structure of large‐river fish populations across main‐stem and tributary habitats

The spatial variability in demographic parameters represents fundamental information for conservation and management of large‐river fish populations. We assessed demographic processes including survival and movement across macroscale habitats in a large‐river network using 2 candidate large‐river species with contrasting life history strategies. We used mark–recapture data and a multistate model framework to estimate survival and transition probabilities between main‐stem and tributary habitats for both channel catfish and shovelnose sturgeon. Annual survival for channel catfish was similar in main‐stem and tributary habitats (range in S = 0.47–0.58). Annual survival for shovelnose sturgeon was less in the tributary (S = 0.68) compared with the main stem (S = 0.83). The probability of movement among macroscale habitats differed between species. However, the greatest probability of movement occurred from the tributary to the main‐stem for both channel catfish (ψ = 0.42) and shovelnose sturgeon (ψ = 0.27). Movement between main‐stem and tributary rivers may be a prominent characteristic for both channel catfish and shovelnose sturgeon and could influence population demographic rates and abundance across systems. Riverine fish populations are likely structured across multiple salient scales—including tributary and main‐stem habitats. Consideration of connectivity across tributary and main‐stem habitats with respect to species' life history strategy and life stage may better integrate a systems' perspective for conservation and management of large‐river fish populations.     

Recruitment Sources of Channel and Blue Catfishes Inhabiting the Middle Mississippi River

Insight into environments that contribute recruits to adult fish stocks in riverine systems is vital for effective population management and conservation. Catfishes are an important recreational species in the Mississippi River and are commercially harvested. However, contributions of main channel and tributary habitats to catfish recruitment in large rivers are unknown. Stable isotope and trace elemental signatures in otoliths are useful for determining environmental history of fishes in a variety of aquatic systems, including the Mississippi River. The objectives of this study were to identify the principal natal environments of channel catfish Ictalurus punctatus and blue catfish Ictalurus furcatus in the Middle Mississippi River (MMR) using otolith stable oxygen isotopic composition (δ¹⁸O) and strontium : calcium ratios (Sr : Ca). Catfishes were sampled during July–October 2013–2014, and lapilli otoliths were analysed for δ¹⁸O and Sr : Ca. Water samples from the MMR and tributaries were collected seasonally from 2006 to 2014 to characterize site‐specific signatures. Persistent differences in water δ¹⁸O and Sr : Ca among the MMR and tributaries (including the upper Mississippi, Illinois, and Missouri rivers as well as smaller tributaries) were evident, enabling identification of natal environment for individual fish. Blue and channel catfish stocks in the MMR were primarily recruited from the large rivers (Missouri and Mississippi) in our study area, with minimal contributions from smaller tributaries. Recruitment and year class strength investigations and efforts to enhance spawning and nursery habitats should be focused on in large rivers with less emphasis on smaller tributaries. Copyright © 2016 John Wiley & Sons, Ltd.