Occurrence Of Fish Research Articles

Noteworthy occurrences among six marine species documented with community engagement in the Canadian Arctic

Abstract Arctic marine ecosystems are changing, one aspect of which appears to be distributional expansions of sub-arctic species. For Arctic marine systems, there is limited occurrence information for many species, especially those found in restricted habitats (e.g., ice-covered, far north, or deep-water). Increasing observations through on-going Fisheries and Oceans Canada (DFO) community-based monitoring programs (e.g., Arctic Coast, Cambridge Bay Arctic Char stock assessment, Arctic Salmon, and Kugluktuk coastal surveys), community observation networks, and local media have augmented opportunities to document new occurrences of marine fishes. Combined data from historical records and contemporary observations at the local scale can then delineate these among three types of occurrences: gradual distributional expansion, episodic vagrants, and rare endemics. Here we document nine occurrences of unusual sightings across six fish species (Pink Salmon Oncorhynchus gorbuscha, Bering Wolffish Anarhichas orientalis, Greenland Shark Somniosus microcephalus, Broad Whitefish Coregonus nasus, Banded Gunnel Pholis fasciata and Salmon Shark Lamna ditropis) from six northern Canadian communities and classify the nature of each observation as rare, vagrant, or expanding distributions. Uniting scientific and local observations represents a novel approach to monitor distributional changes suitable for a geographically large but sparsely populated area such as the Canadian Arctic. The new occurrences are important for discerning the potential effects of the presence of these species in Arctic ecosystems. These observations more broadly will build on our understanding of northern biodiversity change associated with warming Arctic environments.

A study on some commercial fishes of Nyaw-byin coastal water, Launglone Township, Tanintharyi region, Myanmar

A total of 10 species (nine families of Belonidae, Clupeidae, Chirocentridae, Mugilidae, Carangidae, Drepaneidae, Lutjanidae, Monodactylida and Sciaenidae under 4 orders) of some commercial fishes was collected from Nyaw-byin coastal water, Launglone Township from April 2019 to March 2020. The collected specimens comprised Albennes hians, Tennualosa ilisha, Chirocentrus dorab, Mugil cephalus, Megalaspis cordyla, Scomberoides tala, Drepane punctata, Lutijanus lunulatus, Monodactylus argenteus and Nibea soldado. The distribution and occurrence of some commercial fishes is present in all year round. In addition, habitats of ecah species, local distribution of some commercial fishes are briefly described.

Drastic reduction of the functional diversity of native ichthyofauna in a Neotropical lake following invasion by piscivorous fishes

Abstract Biological invasions are leading several species to extinction and are projected as a main driver of biodiversity changes in lakes for this century. However, the knowledge of their impacts on the Neotropical ichthyofauna over time remains largely incipient, especially when considering the functional diversity of native communities. Here we aim to identify the effects of non-native species, especially the non-native piscivorous Cichla kelberi and Pygocentrus nattereri, on the functional diversity of the native ichthyofauna of the Carioca Lake, Middle Rio Doce basin, state of Minas Gerais. Using fish occurrence data for eight years from 1983 to 2010 combined with an ecomorphological-trait analysis, we found that while the native species richness dropped to 56%, the functional richness is only 27% of that found before introductions. In other words, more than species, the ichthyofauna suffered an impressive decline in the range of functional traits, which can further have severe impacts on ecological processes within that system. When considering all the components of the current ichthyofauna (native and non-native species), neither taxonomic nor functional richness have changed over time. However, even keeping biodiversity levels, non-native species are not able to fully compensate for the extinct native ones in terms of functions.

Efficacy of environmental DNA sampling to detect the occurrence of endangered coho salmon (Oncorhynchus kisutch) in Mediterranean‐climate streams of California's central coast

AbstractAnalysis of environmental DNA (eDNA) has emerged as an important tool for investigating the occurrence and distribution of fish and other species in aquatic environments. However, in lotic systems, uncertainty remains about how environmental factors influence the downstream transport, degradation, and dilution of eDNA, and hence how detection probability varies with distance from the eDNA source. We conducted cage experiments and paired eDNA and snorkel surveys to evaluate the potential for eDNA methods to detect endangered coho salmon in Mediterranean‐climate streams of the Santa Cruz Mountains, California. Juvenile coho salmon at two densities were placed in cages, and water samples were collected and analyzed (qPCR) at seven locations from 10 to 1,000 m downstream. Although we detected coho salmon eDNA up to 1,000 m downstream of the cage, the vast majority of detections were within 200 m, and detections at greater distances occurred only at the higher fish density. In field collections from 21 stream reaches across the Santa Cruz Mountains, eDNA methods and snorkeling produced identical outcomes in terms of reach‐level detection of coho salmon. Probability of occurrence in a water sample and detection in a qPCR replicate both increased with observed fish density; however, even at the lowest densities, a protocol of three water samples and two qPCR replicates resulted in a >90% cumulative probability of detection. Overall, our studies suggest that detection probability decreased rapidly with distance in Santa Cruz Mountain streams, likely because low stream discharges, slow transport velocities, and strong interaction between the water column and stream substrate result in rapid degradation or settling of eDNA. Our findings thus support the use of eDNA methods for detecting rare species, but also indicate that local conditions strongly influence transport dynamics and hence need to be considered when developing survey designs.

Species Distribution Modelling via Feature Engineering and Machine Learning for Pelagic Fishes in the Mediterranean Sea

In this work a fish species distribution model (SDM) was developed, by merging species occurrence data with environmental layers, with the scope to produce high resolution habitability maps for the whole Mediterranean Sea. The final model is capable to predict the probability of occurrence of each fish species at any location in the Mediterranean Sea. Eight pelagic, commercial fish species were selected for this study namely Engraulis encrasicolus, Sardina pilchardus, Sardinella aurita, Scomber colias, Scomber scombrus, Spicara smaris, Thunnus thynnus and Xiphias gladius. The SDM environmental predictors were obtained from the databases of Copernicus Marine Environmental Service (CMEMS) and the European Marine Observation and Data Network (EMODnet). The probabilities of fish occurrence data in low resolution and with several gaps were obtained from Aquamaps (FAO Fishbase). Data pre-processing involved feature engineering to construct 6830 features, representing the distribution of several mean-monthly environmental variables, covering a time-span of 10 years. Feature selection with the ensemble Reciprocal Ranking method was used to rank the features according to their relative importance. This technique increased model’s performance by 34%. Ten machine learning algorithms were then applied and tested based on their overall performance per species. The XGBoost algorithm performed better and was used as the final model. Feature categories were explored, with neighbor-based, extreme values, monthly and surface ones contributing most to the model. Environmental variables like salinity, temperature, distance to coast, dissolved oxygen and nitrate were found the strongest ones in predicting the probability of occurrence for the above eight species.

Diet of Leach's Storm-Petrels (Hydrobates leucorhous) among Three Colonies in Atlantic Canada

Hydrobates leucorhous (Leach's Storm-petrel) is widely distributed throughout the Northern Hemisphere, but colonies in Atlantic Canada are declining. We assessed the diet of Leach's Storm-petrels from colonies at Country and Bon Portage islands, NS, Canada, and Kent Island, NB, Canada, during the chick-rearing period in 2018 and 2019. Prey composition varied between years and between colonies. In 2019, when sample sizes were similar across colonies, occurrence of fish varied widely among colonies, being high at Country Island (77.3%), intermediate at Bon Portage Island (22.2%), and low at Kent Island (4.8%). Euphausiids, the main crustacean component of the diet across all colonies, occurred frequently at Kent (100%) and Bon Portage (94.4%) islands, and in 63.6% of samples at Country Island. Pooled samples from all 3 colonies in this study had significantly lower fish occurrence (P < 0.01) but similar occurrence of crustaceans (P = 0.93) than previous studies of the diet of Leach's Storm-petrels elsewhere in eastern North America. The dietary variation we found among Leach's Storm-petrel colonies may explain some of the patterns of mercury in tissues for birds at these sites.

Effects of water flow on ventilation rate and plasma cortisol in Nile tilapia introduced into novel environment

Water flow is a typical hydrodynamic variable of natural occurrence in fish’s lifetime and understanding its impact on biological processes (e.g. stress) can contribute to improve welfare in captive/farmed fish. For that, we tested whether water flow is a stressor by itself in a non-rheophilic (i.e. theoretically sensitive to water flow) fish species: Nile tilapia (Oreochromis niloticus). Additionally, this species was chosen due to its importance for world aquaculture and because is cultivated in a number of systems which the water flow could potentially be a stressor such as indoor tanks, recirculating aquaculture systems, biofloc system and cages. Here, we exposed fish to a novel environment with (520 L h−1) or without a deliberated water flow, and we measured plasma cortisol and ventilation rate (VR) as indicators of stress. In a first experiment, the VR was reduced by flow immediately after tilapia transference to a novel environment (16 min of evaluation), but cortisol was not affected. The plasma cortisol levels were also measured in a second experiment, 30 min, 1, 2 and 4 h after transference to a novel environment, but was also not affected by the presence of flow. In a theoretical perspective, flow is not a stressor by itself in a non-rheophilic species. It acted as a hydrodynamic factor that decrease the magnitude of ventilation response in a fish introduced into a novel environment, without effects on plasma cortisol levels. Therefore, the water flow eventually can be used to assist fish oxygenation after a disturbance event, such as introduction into a novel environment.

Current assessment of species composition and biological characteristics of fishes in the transboundary rivers in Turkey

The freshwater fishes of Turkey have been studied for more than 150 yr. However, a nation-wide inventory of freshwater fish occurrences in all transboundary river basins (Euphrates–Tigris, Coruh, Kura–Araks, Maritsa and Orontes) has been neither studied nor published. This work is the first extensive study of the composition and biological characteristics of the freshwater fish fauna of the transboundary rivers in Turkey, with special reference to the native and non-native status of species, and the spatial patterns of species e.g., abundance category, endemism, main threats, movement patterns, habitat guild, feeding guild, and reproductive guild. It is determined that a total of 184 fish species in 25 families (including 15 species which are not native, and 30 species are considered as endemic) live in the transboundary river basins in Turkey. Of the 184 fish species: 19 species are abundant, 57 species decrease, and 101 species are data deficient based on IUCN Red List (International Union for Conservation of Nature and Natural Resources). One of the main threats to freshwater fish occurrences in all transboundary river basins are dams. Most fish species in the area are threatened by dams, water extraction, and habitat degradation.

Spatial distribution of native fish species in tributaries is altered by the dispersal of non-native species from reservoirs

Reservoirs are known to alter temperature and flow regimes, shift nutrient cycles, reduce downstream species diversity and enable a predominantly upstream spread of non-native species. However, information about the seasonal dynamics of the spread of non-natives from a reservoir to its tributaries and the further consequences regarding the spatial distribution of native species is rare. We observed the occurrence of fish in the Vltava River and its tributaries (Elbe catchment area, central Europe) upstream of the Lipno Reservoir for five consecutive years. We radio-tagged two non-native and four native species. To detect assemblage spatial variability, we sampled sites in the study area by electrofishing twice per year (spring and autumn). We expected seasonal trends in non-native species appearance in upstream reservoir tributaries and, conversely, low motivation of native fishes to descend to the reservoir. By analysing nearly 3000 individuals of 21 species from the longitudinal profile of the study area, we observed an effect of reservoir distance on the native species ratio in the upper Vltava catchment area, i.e., an increase in distance increased the native species proportion, and the opposite was observed for non-native species. Analyses of 3798 tracking positions of 193 tagged individuals showed massive spring dispersal of non-native species from the reservoir to the main tributary, the Vltava River, and their return to the reservoir for wintering. Their upstream movement positively correlated with an increase in flow rate. Native Salmo trutta showed a specific shift from the Vltava River to smaller streams during the summer, when the presence of non-native species in the Vltava River was most significant. These findings indicate that non-native species repeatedly spread from the reservoir to the upstream river stretch and its tributaries and potentially compete with native species for resources.

Occurrence of a Cyprinid Fish (Leuciscinae) from Latest Neogene (?Pliocene) Sediments of Chotanagpur Plateau, Eastern India

Occurrence of a Cyprinid Fish (Leuciscinae) from Latest Neogene (?Pliocene) Sediments of Chotanagpur Plateau, Eastern India

Fish occurrence in the middle Volga and upper Don regions (Russia).

BackgroundIn ichthyological publications from both Russia as a whole, and from the study region, lack of data indicating the actual results of observations in a specific place all result in publication of a generalised analysis. Although our publications contain such data, they are, however, not convenient for users performing global analysis. The main purpose of publishing a database is to make our data available in the global biodiversity system to a wide range of users. Dataset represents a significant addition to the distribution of species in this area. The data can be used to analyse future changes in ichthyofauna, as well as to help the authorities to manage their territory more efficiently.This publication describes a dataset that contains information on fish encounters in the Upper Don basin and the middle Volga (centre of the European part of Russia) over a 30-year period (1990-2020). The dataset contains information on 6400 occurrences of 394341 specimens of 56 species, 99.9% of specimens being identified to the species level. A total of 883 sites were studied, of which 253 were in lentic biotopes (lakes - 121, ponds - 123, backwater - 5, reservoir - 3, pit - 1), 630 were in lotic (rivers - 628, stream - 1, channel - 1). One collecting site has an average of 7.2 species (from 1-21 species per location). Only those species that form self-reproducing populations are given. The dataset is a compilation of data from several working author groups. All observations have precise geo-referencing with the names of water bodies (rivers, lakes etc.).New informationAll presented data are published in the form of a database for the first time. Some data form the basis of previously-published works (3998 observations, 62%) and some are published for the first time (2402 observations, 38%). A large amount of data comes from small water bodies that have been neglected by previous researchers.

Trophic interactions will expand geographically but be less intense as oceans warm.

Interactions among species are likely to change geographically due to climate-driven species range shifts and in intensity due to physiological responses to increasing temperatures. Marine ectotherms experience temperatures closer to their upper thermal limits due to the paucity of temporary thermal refugia compared to those available to terrestrial organisms. Thermal limits of marine ectotherms also vary among species and trophic levels, making their trophic interactions more prone to changes as oceans warm. We assessed how temperature affects reef fish trophic interactions in the Western Atlantic and modeled projections of changes in fish occurrence, biomass, and feeding intensity across latitudes due to climate change. Under ocean warming, tropical reefs will experience diminished trophic interactions, particularly herbivory and invertivory, potentially reinforcing algal dominance in this region. Tropicalization events are more likely to occur in the northern hemisphere, where feeding by tropical herbivores is predicted to expand from the northern Caribbean to extratropical reefs. Conversely, feeding by omnivores is predicted to decrease in this area with minor increases in the Caribbean and southern Brazil. Feeding by invertivores declines across all latitudes in future predictions, jeopardizing a critical trophic link. Most changes are predicted to occur by 2050 and can significantly affect ecosystem functioning, causing dominance shifts and the rise of novel ecosystems.

Effect of Diverse Abiotic Conditions on the Structure and Biodiversity of Ichthyofauna in Small, Natural Water Bodies Located on Agricultural Lands

Mid-field natural ponds promote regional biodiversity, providing alternative habitats for many valuable animal species. The study’s objective was to determine the most important abiotic factors, including hydrochemical and morphometric parameters, affecting fish occurrence in natural, small water bodies on agricultural lands. The studies were conducted in nine randomly selected water bodies located in Poland (the North European Plain). Eleven species of fish were recorded in the waterbodies, with the most abundant being cyprinids (mainly crucian carp). Canonical correspondence analysis (CCA) showed that an increase in oxygenation, temperature, amount of macrophytes, and K concentration and a decrease in the concentration of phosphates, electrical conductivity (EC), Mg, and Cl is associated with the most beneficial living conditions for the most frequently occurring species in the studied water bodies—crucian carp and tench. Aside from the hydrochemical parameters of water in the natural ponds, the number of fish correlates with the basin area and the pond area, maximum depth, area of the buffer zone surrounding the water bodies, and the number of macrophytes. This last factor also has a significant influence on the species’ abundance in the water bodies. Fish occurrences in mid-field ponds and common knowledge on their important role in the environment require taking steps to provide fish protection.

Understanding enviro-climatological impact on fish biodiversity of the tropical floodplain wetlands for their sustainable management

Inland open water fisheries around the world are threatened due to growing anthropogenic pressures, climate change and overexploitation of the germplasm resources. Understanding how the floodplain wetland fish diversity responds to these unprecedented challenges is critical for developing alternative management and mitigation strategies in vulnerable wetland ecosystems. This communication elucidates the changing pattern of fish diversity in three moderately impacted tropical floodplain wetlands namely Bhomra, Mathura and Chandania in the lower Ganges basin during the year 2017–2019. Experimental fishing using gill net, drag net and cast net was carried out monthly to assess the fish diversity pattern in the three wetlands. Enviro-climatological parameters were assessed, and the important parameters influencing fish diversity were identified. Most of the critical environment parameters including pH, DO, water temperature were in the favourable range for fish. ANOVA indicated that pH, TDS, conductivity, salinity, transparency, depth and hardness showed significant difference (p < 0.05) among the three wetlands. Thirty-six fish species were recorded from the three wetlands out of which 2 species were vulnerable (VU) and 1 species was near threatened (NT). Species richness declined in all the studied wetlands ranging from 22.85 to 54% from the year 2002. The Canonical Correspondence Analysis showed a varying relationship of climatic and environmental parameters with the occurrence of fishes indicating species-specific adaptive capacity. The study also revealed a decrease in fish production (1991 to 2017) with the decreasing trend in rainfall and the increasing trend in temperature showing enviro-climatological influence. The new information generated would help to manage the wetland resources for sustainable fisheries enhancement and biodiversity conservation.

Experimental infection by Aeromonas hydrophila in Piaractus mesopotamicus: DL50, neurological disturbances, and mortality

Aeromonosis is an infectious disease of high occurrence in captive fish. It manifests mainly as hemorrhagic septicemia. This study aimed to evaluate the physiopathology manifestations of septic aeromonosis in Piaractus mesopotamicus, considering its clinical manifestations, mortality rates, anatomopathology, and anti-iNOS immunolabeling in the brain. Fish were inoculated in the coelomic cavity with increasing concentrations of A. hydrophila: 1.5 × 108; 1.8 × 108; 2.1 × 108; 2.4 × 108; 2.7 × 108 CF mL−1, histopathology, and anti-iNOS immunolabeling in brain. The animals present erratic swimming (swirling), depigmentation, petechiae, skin suffusions, and high mortality rates up to 100% according to the inoculum concentration. The DL50-96 h was estimated in 1.806 × 108 CFU mL−1. Fish inoculated with 2.1 × 108 CFU mL−1 presented 100% mortality rate. Fish presented neurological signs, congestion, extensive hemorrhage, and glial cells activity confirmed by the anti-iNOS labelling. In addition, the inoculated bacteria was reisolated from the brains. The results demonstrated that aeromonosis physiopathology is multifactorial and the observed neurological signs were caused by the inoculated bacteria. These findings highlight the need for differential diagnosis with other infections that produce encephalitis.

Temporal patterns of fish occurrence of the euryhaline sector of a subtropical estuary, southern Brazil

Fish fauna was studied in five sites of the shallow infralittoral of the Paranaguá Bay during the period from October 1999 to September 2000. At each sampling site, fish were sampled with other trawls, salinity and temperature were measured, water samples were taken from the bottom of the water column for determination of dissolved oxygen, dissolved inorganic nitrogen and phosphate. The spatial and temporal behavior of the environmental variables was analyzed by a Principal Component Analysis; Cluster Analysis was used to gather the sampling sites, and Factorial Correspondence Analysis was applied to the most abundant species. Temperature was the most important variable for the distribution of the months, allowing the division of the study period into hot and cold months. The temporal variation in the fish fauna composition was indicated by cluster analysis, with highest percentages of dissimilarity between the sampling sites during hot months. The variation in dissimilarity between the sites occurred due to differences in the number of individuals and species of the catches. The high frequencies of occurrence of Anisotremus surinamensis, Etropus crossotus, Genidens genidens, Micropogonias furnieri and Sphoeroides greeleyi were related to high temperatures. The greatest number of fish and species observed in hot months may be related to the life cycle of many species, which reproduce in warmer months, and whose offspring use estuaries as breeding areas.

Is this rock pool suitable habitat? Fish diversity in intertidal rock pools of El Zonte, El Salvador

Occurrence, abundance, and distribution of fishes in intertidal rock pools are influenced by environmental and biological traits that determine habitat quality. Fishes actively inhabit areas that represent the most suitable habitat for their development. For the intertidal fish community of El Zonte, physical and structural traits of rock pool habitat, as well as habitat complexity, were examined in relation to fish occurrence, abundance, species richness, and body length. Fish occurred in only 18 (40%) of 45 rock pools. A total 309 fish representing 9 species were recorded. The most abundant species were Bathygobius ramosus (160 individuals, 52%) and Abudefduf concolor (88 individuals, 28%). Fishes were absent in rock pools of volumes less than 0.29 m3 and with surface roughness lower than 4.7%. Rock pool volume and surface roughness were related to fish abundance and species richness. Surface roughness was more important to fish abundance and species richness in rock pools of small volumes, but its contribution was limited in larger rock pools. Fish length and rock pool volume were also related, with larger fish generally occurring in larger rock pools. This study presents insights into the factors influencing fish occurrence in tropical intertidal rock pool systems of the Tropical Eastern Pacific.

Volcanic activity controls cholera outbreaks in the East African Rift.

We hypothesized that Cholera (Vibrio cholerae) that appeared along Lake Kivu in the African Rift in the seventies, might be controlled by volcano-tectonic activity, which, by increasing surface water and groundwater salinity and temperature, may partly rule the water characteristics of Lake Kivu and promote V. cholerae proliferation. Volcanic activity (assessed weekly by the SO2 flux of Nyiragongo volcano plume over the 2007–2012 period) is highly positively correlated with the water conductivity, salinity and temperature of the Kivu lake. Over the 2007–2012 period, these three parameters were highly positively correlated with the temporal dynamics of cholera cases in the Katana health zone that border the lake. Meteorological variables (air temperature and rainfall), and the other water characteristics (namely pH and dissolved oxygen concentration in lake water) were unrelated to cholera dynamics over the same period. Over the 2016–2018 period, we sampled weekly lake water salinity and conductivity, and twice a month vibrio occurrence in lake water and fish. The abundance of V. cholerae in the lake was positively correlated with lake salinity, temperature, and the number of cholera cases in the population of the Katana health zone. V. cholerae abundance in fishes was positively correlated with V. cholerae abundance in lake water, suggesting that their consumption directly contaminate humans. The activity of the volcano, by controlling the physico-chemical characteristics of Lake Kivu, is therefore a major determinant of the presence of the bacillus in the lake. SO2 fluxes in the volcano plume can be used as a tool to predict epidemic risks.

Microplastic and tire wear particle occurrence in fishes from an urban estuary: Influence of feeding characteristics on exposure risk

The influence of feeding behavior and feeding ecology on microplastic occurrence in fishes in an urbanized estuary was studied by surveying microplastics in the digestive tracts (gut) of five fish species: the planktivorous Bay Anchovy and Atlantic Menhaden, the piscivore Spotted Seatrout, the benthivore Spot and the detritivore/benthivore Striped Mullet. Microplastics were found in 99% of fishes collected with an average of 27 microplastics per individual fish, 6 microplastics per gram of fish, and 21 microplastics per gram of gut, although exposure varied among species. Atlantic Menhaden possessed significantly more microplastic per fish weight than other species, which may be attributed to their regular ingestion of marine snow aggregates. Fibers were the most common type of microplastic in all fishes, and suspected tire wear particles were found in 14% of individuals across all five species, constituting the first evidence of tire wear particle consumption in field-collected organisms.

Climate change: A potential risk to cage culture and genetic structure of native fisheries in fish cage‐installed inland lakes

AbstractFish cage aquaculture (FCA) in lakes is a viable climate change (CC) mitigation approach; however, deficiencies in monitoring, early warning and risk planning could threaten its sustainability. Thus, the present study focused on examining the experiences with CC and its risks to cage fish culture, and phenotypic structure of a typical endemic fishery in fish cage‐installed (FCI) and fish cage‐free (FCF) lakes. Using a structured questionnaire, fisherfolks of typical FCI and FCF lakes in southwestern Nigeria were consulted for their local experiences regarding CC variables, effects on cage aquaculture and the occurrence of caged fish in their fish catches. For phenotypic structure analysis, size cohorts of cage‐cultured (CCU) and wild‐caught (WC) Oreochromis niloticus from FCI (CCUFCI and WCFCI), and WC from FCF (WCFCF) were obtained and analysed for phenotypic differences (p &lt; .05) and mix‐up through cluster/linkage analysis. Respondents experienced unpredictable climatic conditions, increased rainfall fluctuations and declining rainfall (86.4; 47.1%, 50.0; 64.7%, 100.0; 88.2%, in FCI and FCF lakes, respectively), indicating that CC affects cage culture, induces cage damage and floods, and results in caged fish escapes (40.9; 35.3%, 81.8; 11.8%, 95.5; 41.2% in FCI and FCF lakes, respectively), while caged fishes occur in fisherfolks’ catches (63.6% FCI). Phenotypically, WCFCF and WCFCI were similar, but differed from CCUFCI for pre‐dorsal length. WCFCF and WCFCI differed for caudal peduncle lengths. In addition, some individuals of CCUFCI clustered with WCFCI and WCFCF, rather than their population cohorts. Climate change impacts on FCA lakes have implications regarding caged fish escapes. Phenotypic structures indicated a possible mix‐up of caged and wild O. niloticus populations. Thus, monitoring, control and surveillance (MCS) of cage culture in lakes is necessary, and development of genetic markers for endemic species would also facilitate MCS.