Eel Catch Research Articles

Trophic niche of a nonnative invader and environmental drivers of its increasing populations in the coastal Everglades

AbstractThe Florida Everglades is a critically important, but highly threatened ecosystem that is becoming increasingly susceptible to the invasion of non-native species. This study investigated the ecological role of the invasive peacock eel (Macrognathus siamensis) within this ecosystem using 15 years of electrofishing data and stable isotope analysis. We investigated the population trends of peacock eels at the marsh-mangrove ecotone of the Shark River Estuary, the environmental factors contributing to their abundance, and the potential interactions they may have with native fish assemblages and coastal food webs. We used stable isotope analysis to provide insights into the basal resource contribution to peacock eels and hypervolume analysis to determine peacock eel trophic niche size and overlap with native species. Results of this study found that peacock eel abundance has rapidly increased, and their populations are strongly related to hydroclimatic regimes. Peacock eel abundance was positively associated with warmer water temperatures and greater marsh inundation periods. The trophic niche of peacock eels was significantly smaller in volume than that of native sunfishes (Lepomis spp.) indicating lower intraspecific resource use variability and suggesting a limited potential for inter-specific competition with these taxa. However, in recent years, the catch of peacock eels has outnumbered the catch of all native sunfishes combined. The feeding habits and pervasiveness of peacock eels in the coastal Everglades could lead to a decrease in abundance of benthic prey items targeted by peacock eels and alter food web dynamics in the system. Based on these data, peacock eel populations are predicted to continue to increase, highlighting the importance of continued monitoring of their potential impact on native fish assemblages and food webs.

Participatory stock assessment in West Java contributes to the management of glass eel fisheries in Indonesia

Following the decline of Japanese eel catches and the EU European eel trade ban, other regions, such as Southeast Asia, have become increasingly important sources of juvenile anguillid species for aquaculture. Although appropriate fishery management of tropical eel species is urgently required, data collection by the government or scientific authorities is extremely difficult, because tropical glass eel fisheries are small-scale fisheries conducted in the Global South, where expertise and resources are sometimes limited. To collect data on glass eel fisheries, participatory stock assessments were conducted in West Java, Indonesia, where a Fishery Improvement Project (FIP) and an Aquaculture Improvement Project (AIP) were launched in collaboration with industries, middlemen, fishermen, NGOs, national and local agencies, and scientists. This participatory study successfully collected data on more than 3000 daily fishing practices from approximately 400 fishermen in a single water system in 2019. Even though the assessment was not species-specific, the data collected allowed estimation of the natural mortality rate as being 0.011 day−1. The annual exploitation rate of the glass eel fisheries was estimated as 24.9%, based on a generalised depletion model developed for the data-limited situation where only fishery catch and effort data are available. The data collection scheme for glass eel fisheries was disseminated by local and national agencies to glass eel fishermen in Indonesia and contributed to developing the Eel Conservation National Action Plan.

Glass eels at the continental edge of Europe: revisiting catchment recruitment at the international River Minho/Miño

The glass eel catch from the international River Minho, western Iberian Peninsula, forms the southernmost Atlantic series in the composite index outside the North Sea assessing European eel recruitment. Here, new experimental yield data from the lower estuary (1981–2022) and fishers´ daily records (1990–2022) were modelled to describe and compare seasonal and interannual trends. Seasonality matched river discharge climatology, possibly a more general feature in the southern range of the species distribution, with the difference between high and low season becoming less marked in recent periods of lower abundance. Glass eel yield showed a sharp decline during the 1980s, in line with the recruitment index outside the North Sea and with total Minho catch, but not with recent local estimates of catch per unit effort. This decline is corroborated by trends in fishers´ daily records, suggesting that the reduction in effort in the Minho was the consequence of a gradual adjustment to recruitment in the catchment mediated by progressively tighter local management measures. The inefficiency of fisheries regulatory measures to guarantee stock recovery alone calls for more comprehensive measures to reverse anthropogenic impacts on continental eel populations, but the task seems Herculean.

Effect of rainfall on water condition and catch results of eel (Anguilla spp.) in Cicatih River, Sukabumi, West Java

Indonesia is one of the countries with the largest eel catches in the world and is very vulnerable to climate change, especially with rainfall. Rainfall affects fishing activities and the surrounding aquatic environment. Fish resources in the Cicatih River are quite diverse, one of which is high economic fish, namely eel. This study aims to provide information about rainfall’s effect on eel catch results in Cicatih Rives, Sukabumi Regency. Sampling was conducted for six months, from August 2021 to January 2022. The method I use in this research is water condition and relationship analysis for water quality using APHA 2017 and analysis of the relationship between rainfall and fish catches. The result shows that the water quality of the Cicatih River is still in the optimal range for eel life. Still, there are water chemistry parameters that exceed the quality standard, and total nitrogen levels exceed 10mg/l. Most of the large eels in the Cicatih River were caught in the rainy season. Rainfall also affects the duration when fishing, and it is negatively correlated. High rainfall affects the time of fishing, which in turn affects the number of eel catches.

Mixed Methods Approach in Documenting Aquaculture Practices and Market Dynamics of the Freshwater Eel Anguilla spp. Industry in the Philippines

Freshwater eels are emerging high-value species in aquaculture in the Philippines. However, the freshwater eel industry in the country remains under-documented, and most of the culture technologies employed are based on temperate eel culture. This study employed a mixed methods approach in primary and secondary data gathering. Key industry players across the value chain were identified and interviewed from February to October 2017 to gather baseline information on aquaculture practices, glass eel capture fisheries, and trading of anguillid eels. Secondary data from BFAR supplemented interview findings. Industry practices in 25 eel farms across the country were documented, the majority (80–85%) of which were nursery farms found in Regions 3 and 4A. There were five grow-out farms, with the largest production facility in Cabadbaran, Agusan del Norte. Different culture facility designs, glass eel stocking practices, water management, aeration systems, feeding schemes, and disease management were described. Most farms used concrete tanks with flow-through systems stocked at 500–1500 pcs/m2 and commercial feeds with binders, bloodworm, or trash fish as feeds. Four major glass eel collection sites were identified: Cagayan, the Davao region, General Santos-Sarangani, and Cotabato City-Maguindanao. The glass eel supply chain starts with collectors, followed by stockers and consolidators who consolidate glass eel catch prior to selling to growers or traders. After the desired eel size (6 inches) is achieved through culture, growers or traders sell the eels to exporters, local institutional markets, and local eel processing plants. The results of this study provide essential information that will pave the way for science-based research to improve the existing culture practices and fisheries policies that will help boost aquaculture production and guide proper management programs.

К вопросу обоснования величины коэффициента промыслового возврата европейского угря (Anguilla anguilla) в заливах Калининградской области

The cessation of stocking of the Vistula Lagoon with eels by Poland in the period from 1995 to 2004, and the ongoing depression of the eel population, led to a decrease in eel catches in both parts of the bay to 4–5 tons / year by the end of the first, most of the second decade of the 21st century. The tendency of eel population decrease was even more pronounced in the Curonian Lagoon, which has never been stocked with eel in historical retrospective. Eel catches in the Russian part of the bay fell from 150 tons in 1970 to 3-4 tons by the 1990s. and less than 1 ton in the present century. Stocking pasture reservoirs with young eels is a way not only to preserve eel stocks, but also to reasonably increase catches. In solving this problem, the question of the value of the commercial return coefficient becomes.

Capture-based aquaculture of glass eel nurseries, Anguilla bicolor in Segara Anakan, Cilacap, Central Java, Indonesia

Capture-based aquaculture specially considers the fattening or on-growing of species which is based on the wild-caught seed. The survey was conducted to evaluate the sustainability of eel nurseries based on the catch of glass eels carried out by aquafarmers in Segara Anakan Cilacap, which decreased after the pandemic occurred in this region. Before the Covid-19 pandemic, there were 50 glass eel aqua-culturists, however during and after pandemic there was 29 glass eel aqua-culturists and mostly in Kedungreja District. There were two glass eel nurseries areas in Cilacap, namely around the Serayu and Citanduy rivers. In the east, there are areas of Maos and Kesugihan, while in the west in Kawunganten, Kaliwungu-Kalicengis Kedungreja and Gandrungmangu. The technology of the glass eel nursery was reliable, in the seedling areas, Segara Anakan, where most eels were produced.

The study of European eel, Anguilla anguilla in the RiverNeretva estuary (Eastern Adriatic Sea, Croatia) using traditional fishery gear

Samples of the European eel, Anguilla anguilla from two different habitats in the River Neretva estuary region were analysed using two different traditional fishery gear, in the period from 2016 to 2019. The monthly eel catches in ten traditional fyke nets in Parila lagoon varied from 4.4 to 12.7 kg (±2.45 kg) in 2016 and 2.4 to 9.6 kg (±2.01 kg) in 2019. There were no statistical differences between monthly and total weights recorded in 2016 and 2019 (t=1.04; p=0.312). The b-coefficient of the length-weight (LW) relationship for the freshwater eel samples varied from 3,1036 to 3,3206 duringtwo-year period of the sampling. The LW relationship for the brackish population was significantly lower (b-coefficient 2,6513). The dominant eel stage in both sites was yellow eel, while silver stage was scarce. The fishery with traditional devices revealed that efficiency of these artisanal tools is low, pointing to poor abundance of eel in their common habitats. The recorded catch using bigger traditional eel trap gear during autumn spawning migrations was also dominated with yellow stage, while silver eel represented only 15,4% of the catch. The infestation of eels with the parasite,Anguillicoloides crassus was significantly higher in freshwater habitat (41% of eel specimens infested) than in brackish, Parila lagoon (7%). Poor efficiency of traditional gear, bad length and weight structure of the population and low b-coefficients of eels in their most important habitat, indicate poor status of European eel population and River Neretva estuarine ecosystems.

KOMPOSISI HASIL TANGKAPAN DAN DAERAH PENANGKAPAN IKAN SIDAT (Anguilla spp) DI SUNGAI LUAS DAN SUNGAI KINAL, KABUPATEN KAUR, PROVINSI BENGKULU

Eel (Anguilla spp) is a fish from the order Anguilliformes belonging to the catadromous fish, fish that migrate between freshwater and marine waters. The activity of catching eel for daily consumption has been carried out by the people of Kaur Regency, but the data related to the type of eel, catch structure, and the eel fishing area in Kaur Regency is still limited, especially in the Luas River and Kinal River. Data and information on eel fisheries in Kaur Regency are expected to be used as basic information in the utilization of eel commodities. This study aims to analyze the structure of eel catches and determine eel fishing areas in the Luas River and Kinal River. Research using eel fishing was carried out in June - August 2021 in Luas river and Kinal river, Kaur regency, Bengkulu. The results of identification of morphological characteristics and comparison of ano-dorsal values ​​found one species of eel, namely Anguilla marmorata with an ano-dorsal ratio of 14.05-18.23%. The Anguilla marmorata eel was caught at every station in the Luas river and Kinal river. Overall, each station in Luas river and Kinal river gets the same H' value, which is relatively moderate. The eel fishing areas in the Luas river and Kinal river are divided into 3 locations, estuary, mid-river, and upstream. The number of catches with the heaviest weights were found at station 3 in Luas river and Kinal river.

Potential Effect of the Intrusion of the Kuroshio Current into the South China Sea on Catches of Japanese Eel (Anguilla Japonica) in the South China Sea and Taiwan Strait

This study examined the effect of the intrusion of the Kuroshio Current (KC) into the South China Sea (SCS) and the Taiwan Strait (TS) (SCS–TS region) on changes in catches of larval A. japonica in the traditional fishing ground waters of Gaoping near southwestern Taiwan in the SCS–TS region. First, the oceanic environment and recruitment trends from 1967 to 2019 were investigated based on secondary data. Then, field surveys were conducted to obtain primary data regarding the intrusion of the KC into the SCS, as well as the changes in the fishing sites and catches of A. japonica in the fall and winter of 2014–2015. Hence, the association between oceanic conditions and the number of A. japonica migrating into the SCS–TS region was explored. From 1967 to 2019, the recruitment proportion in the fishing grounds that formed due to the Kuroshio Branch Current (PKSBC) fluctuated significantly. Overall, positive values were observed for the Oceanic Niño Index for each year with a PKSBC > 50%, corresponding to El Niño conditions. In each year with a PKSBC > 70%, a looping path and a warm–core eddy appeared.

EEL (Anguilla bicolor bicolor) Rearing Techniques at the UPTD for Conservation and Supervision of Marine Fishery Resources of Sicincin, West Sumatra

Eel has a savory meaty taste and contains high levels of Eicosapentaenoic acid (EPA) and Docosahexaenoic acid (DHA). The purpose of this observation was to determine intensive rearing techniques for eel (Anguilla bicolor bicolor) at the UPTD KPSDKP for Conservation and Supervision of Marine Fishery Resources of Sicincin, West Sumatra. The preparations conducted for rearing the eel consist of providing seeds, pond preparation, water supply, feed management, water quality control, disease control, growth sampling, and harvesting eel for consumption size. The eel seeds were obtained from natural catches of glass eel in the Cimandiri river, Pelabuan Ratu, West Java. Preparation of the eel pond included cleaning the concrete pond, filling the water by observing the water input into the eel pond. The provision of water for eel rearing was obtained directly from the Kapalo Ilalang Sicincin irrigation channel to the holding tanks before flowing to the eel rearing pond. Feeding management was carried out 2 times a day, namely the percentages of feeding in the morning (35 %) and at night (55%) with a feeding rate of 3%-5%. The feed provided to these eels was in the form of a paste made of powdery pellets. Measurements of water quality for eel rearing during observations were temperature (27-29°C), pH (6-7), DO (5.9-7.8 ppm), salinity (3-4 ppt) and NH3 (0.02-0.07 mg/l). In our observations, parasites shaped like cotton were discovered, which attacked the eel body, causing death. In growth sampling, the measurement of the length and body weight of the eel once a month is necessary to be done.

Characterizing Downstream Migration Timing of American Eels Using Commercial Catch Data in the Penobscot and Delaware Rivers

AbstractAdult “silver‐phase” American Eels Anguilla rostrata were a focus of commercial fisheries in the 1970s and 1980s, but stocks have been depleted due to many anthropogenic factors. One significant source of mortality occurs during the downstream migration of eels when passing through turbines at hydroelectric facilities. We sought to construct a model to predict eel migration timing to inform optimization of mitigation actions that might reduce mortality. We utilized commercial catch collected from 16 tributaries in the Penobscot River watershed, Maine (2–10 years), and the Delaware River, New York (31 years). A Bayesian hierarchical approach was used to model the relationship between the timing of silver eel capture and environmental conditions that are known to be related to their movements (i.e., river discharge, water temperature, and lunar cycle). Among river systems, daily catch was associated with higher‐than‐average flows, temperatures of 7–22°C, and new lunar phase cycles. A cross‐validation approach to evaluate the ability of the models to make predictions for new data demonstrated a greater ability (higher R2 values) to predict weekly eel catch (0.01–0.92) compared to daily eel catch (0.00–0.42). In addition, we examined the model’s ability to forecast migration events by applying posterior simulations to make predictions of eel catch by ordinal date. Predicted daily eel catch generally followed the trend of observed daily catch and was stronger for the Delaware River (R2 = 0.67) than for Souadabscook Stream, Maine (R2 = 0.07). Sharp pulses in observed catch were not reflected by the predicted catch. Additionally, variability observed among rivers suggests that site‐specific modeling may be advantageous (and necessary) to capture local conditions, thereby improving predictive power. More broadly, our work highlights a novel use of fishery‐dependent data in a Bayesian modeling framework to predict intervals of risk for migrating fish.

The changing times of Europe's largest remaining commercially harvested population of eel Anguilla anguilla L.

This study quantifies the processes involved in regulating the European eel population of Lough Neagh, a lake in Northern Ireland. The relationship between glass eel input and silver eel output for the 1923–1997 cohorts was best described by a Beverton–Holt stock recruitment model. Glass eel input time series was not complete and was thus derived from the relationship between catches elsewhere in Europe and Lough Neagh, together with the addition of stocked glass eel. Silver eel output was the sum of silver eel escapement, catch and yellow eel catch converted to silver eel equivalents. Natural mortality increased with glass eel density, ranging from 0.017 to 0.142 year−1. The mean carrying capacity increased from ≈3.25 M silver eels (≈26 kg ha−1) for the 1923–1943 cohorts to ≈5.0 M (≈40 kg ha−1) for the 1948–1971 cohorts before regressing back to ≈3.25 M. The total silver eel output was highest during the late 1970s/early 1980s at 35–45 kg ha−1 year−1 and lowest during the early years of the 20th century and is currently at 10–15 kg ha−1 year−1. The findings are discussed in relation to (a) the ecological changes that have occurred within the lough, associated with eutrophication and the introduction of roach (Rutilus rutilus L.), and (b) the decline of the wider European eel stock across its distribution range. The findings from this study have relevance for the wider management of the European eel stock.

KINERJA SUPPLY CHAIN MANAGEMENT GLASS EEL (BENIH SIDAT) UNTUK MENUNJANG INDUSTRI PEMBESARAN SIDAT DI PALABUHANRATU

The utilization of glass eel (eel seeds) in the Cimandiri River Palabuhanratu has a very important role to support the supply chain for the eel culture industry. The purpose of this study was to estimate the amount of glass eel catch, describe the glass eel eel supply chain system, and measure the performance of the supply chain in eel culture. The research method uses quantitative methods through direct observation and interviews, as well as case studies of supply chain actors. The results showed that the highest catch of glass eel in 2019 was in June at an average of 14,859 grams (14.9 kg). The highest catch of glass eel occurred in the dry season (June - August), with a total catch of 21,884 grams (21.8 kg). The glass eel supply chain mechanism consists of supply chain flow pattern on the product flow, a good and transparent flow of information on each link, and the distribution of two payment systems, namely cash and credit payments. The supply chain performance in the eel culture industry obtained a performance value of 82.63 which indicates that the achievement of the company's supply chain performance is in the good category, and improvements need to be made especially on the deliver process performance indicators with a value of 2.70.
 Keywords: : glass eel, supply chain, eel, Cimandiri River

Population structure of tropical eel (Anguilla bicolor bicolor) in Cikaso River, West Java

A. bicolor bicoloris a tropical eel subspecies that dominate catches in the coastal areas of West Java, and its conservation status is near threatened. Cikaso River, West Java, becomes eel migration path, while unfortunately, information concerning the stock of eel in this river is still inadequate. The objective of this study was to determine the population structure (size distribution, length-weight relationship, and condition factor) ofA. bicolor bicolorin the Cikaso River. The research was carried out in the main streams of the Cikaso River and the coastal marsh of Ciroyom from January to December 2020. Eel samples were collected using lift-net, fishhook, and traps. The number of eels caught is counted, then the total length and weight are measured. We collected nine elvers and 89 yellow eels, but no silver eel was caught during the study. The elver's total length (TL) ranged from 10.2 to 20 cm, and the TL of yellow eel ranged from 20.1 to 42.2 cm. The catch of eel is dominated by the size of 25-30 cm. The growth pattern of eel in the Cikaso River is positive allometric, with the condition factor of eel ranging from 0.450 to 1.917 (1.160±0.3096).

Conservation Requirements of European Eel (Anquilla anquilla) in a Balkan Catchment

The European eel (Anquilla anquilla) has been declining throughout its area of distribution, is addressed in several pieces of legislation, and is the target of extensive restoration efforts. Therefore, investigating and conserving natural eel habitats is urgently needed. Large, near-natural rivers have become rare in Europe but the Balkans host some of the extant examples. However, several Balkan rivers–among them the transboundary river Vjosa/Aoos of Albania and Greece–are under threat from planned hydropower constructions. This study synthesizes European eel catch data from four institutions and the results of a recent electrofishing survey. Population density and structure as well as habitat choice were studied at different spatial scales. We calculated densities for each meso-habitat (0–1303 ind./ha) and extrapolated these values across three different hydromorphological channel sections (meandering: 70 ind./ha, braided: 131 ind./ha, constrained: 334 ind./ha), resulting in an overall mean density of 168 ind./ha. Proposed hydropower plants would cut off about 80% of the catchment currently accessible and impact river sections downstream of the dams by disturbing hydrological dynamics. By linking study results to relevant legislation and literature we provide evidence-based data for water management decisions. We call for the Vjosa/Aoos to be protected in order to secure its outstanding conservation value.

Modelling daily catches of silver‐phase European eel (Anguilla anguilla) in two hydropower‐regulated rivers

AbstractEstimation of silver eel production, Anguilla anguilla L., is fundamental for the management of eel stocks. In the hydropower‐regulated rivers Shannon and Erne, Ireland, production is calculated using catch data from a conservation trap and transport programme. However, in both rivers gaps in silver eel catch datasets tend to occur, which can lead to biases in production estimates. Generalised additive models (GAMs) were used to model daily catch in these rivers based on a variety of environmental variables. Final models for the Shannon and Erne explained 83.7% and 78.8% of deviance in daily catch, respectively. A second model on the Erne included catch from a nearby fishing site in an attempt to increase explanatory power and explained 91.7% of deviance. Although model accuracy was increased, reliance on catch from another site may limit the applicability of the model. Model predictions were combined with estimates of fishing efficiency to predict production for the Shannon (36,210 kg; 0.85 kg/ha) and Erne (66,899–67,047 kg; 2.55–2.56 kg/ha). These values represented a 9.3% and 2.8%–3.0% increase on production estimated from incomplete catch records alone for the Shannon and Erne, respectively.

The use of otter guards in fyke net surveys and their effect on catches of European Eel Anguilla anguilla

The European eel is critically endangered and European member states are required to undertake measures to ensure the recovery of eel stocks. The otter is also a protected species under international legislation. As a predator of the eel the otter is often caught in fyke nets located close to shore and in shallow water and otter guards can be used to reduce this unwanted by-catch. This study was undertaken to investigate the effect of otter guards in fyke nets on 1) eel catch and 2) eel length frequency and to compare with eels caught in non guarded fyke nets. In seven lakes at each net location a combination of guarded and non-guarded fyke nets were set. A generalized linear mixed model analysis (GLMM) was applied to the eel catch data with treatment (guarded/non-guarded) as the fixed effect. The catch model predicts that on average the catch per unit of effort (CPUE) for a guarded fyke net is 0.5 (95 % CI [0.34−0.73]) and the CPUE for a non-guarded net is 0.7 (95 % CI [0.48–1.0]). Converting the CPUE to numbers of eels, the model predicts that a guarded net will catch 5 eels (95 % CI [3–7 eels]) and a non-guarded net will catch 7 eels (95 % CI [5–10 eels]). A second GLMM analysis investigated the effect of treatment on the length of eels captured in fyke nets. The predicted mean length of an eel for a guarded net is 48 cm (95 % CI [44–52 cm]), and 49 cm (95 % CI [45–54 cm]) for a non-guarded net. Considering the degree of variation within the lake, these results show that there is no impact on the numbers or the length of eels captured in guarded fyke nets. There are more important variables influencing the eel catch within lakes.

Past and lost influence of the Kuroshio on estuarine recruitment of Anguilla japonica glass eels

The present study aims to reveal the influence of path fluctuations of the western boundary current (Kuroshio) and other regional environmental factors on coastal recruitment of transported organisms. As a model species, we chose a catadromous eel species, Japanese eel Anguilla japonica, which is transported poleward by the Kuroshio in early life stages. We analyzed a 50-year record of A. japonica juvenile (glass eel) catch from an estuary (Lake Hamana, Japan) with regional environmental data, using multiple linear regression with stepwise variable selection. Kuroshio path indicator (fishing-season mean of sea level difference between two tide stations), year, or their interaction showed moderate to strong evidence of an effect on the natural log-transformed catch of glass eels in the regression models. Strong evidence of an interaction effect between the Kuroshio path indicator and year was also found on the natural log-transformed catch-per-unit-effort. The estuarine recruitment of A. japonica glass eels was suggested to be positively influenced by nearshore Kuroshio position, but the influence has been lost in recent decades. The present study provides statistically robust evidence of the environment–recruitment relationship (western boundary current–recruitment link) for coastal species. This finding enhances our understanding of coastal recruitment of organisms transported by western boundary currents and is potentially essential in forecasting recruitment for fisheries management and conservation. Furthermore, our findings suggest that stock decline may lead to poorer understanding of environment–recruitment relationship.

Attraction of migrating glass eel (Anguilla anguilla) by freshwater flows from water pumping stations in an urbanized delta system

Most studies on glass eel (Anguilla anguilla) migration are performed in natural estuaries, where they enter freshwater systems to live there for a period of years before they swim back again to the sea to reproduce. In these natural systems, river flows play a major role in attracting and directing migrating eels. However, coastal areas get urbanized more and more and characterized by anthropogenic barriers and hampered or artificial water flows. The effects of these flows on glass eel migration are poorly understood. Therefore, in this study glass eel were sampled at water pumping stations in a constructed part of the Rhine delta in the Netherlands. A mixed linear-effect model was used to determine effects of freshwater flows from water pumping stations on glass eel catch. We found that freshwater flows from water pumping stations had a significant but small effect on glass eel catch. Pumping activity had no significant effect on glass eel catch at sample locations with a continuous freshwater flow from fish passages. However, a low predictive value of the model and low numbers of individuals per sample prohibited strong conclusions on effects of anthropogenic freshwater flows on glass eel migration. More individual tracking techniques should be used to improve understanding migratory behavior of glass eel.