Distribution of Japanese Eel Anguilla japonica Revealed by Environmental DNA

Kasai, Atsushi; Yamazaki, Ayano; Ahn, Hyojin; Yamanaka, Hiroki; Kameyama, Shuichi; Masuda, Reiji; Azuma, Nobuyuki; Kimura, Shingo; Karaki, Tatsuro; Kurokawa, Y; Yamashita, Yoh

doi:10.3389/fevo.2021.621461

Cited by 27 publications

(33 citation statements)

References 40 publications

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“…In addition, the wild eel density was lower in the Sanbongi and Nagasawa rivers than in the Hatauchi and Kaizoko rivers based on both the conventional sampling method and eDNA analysis. The wild eel distribution observed in the study rivers is consistent with the previous studies that investigated the distribution of Japanese eels in Japan (Kasai et al , 2021; Yoneta et al , 2019). Thus, the lower wild eel densities in the Sanbongi and Nagasawa rivers may be explained not by differences in the amount of food resources, but by lower recruitment of eels due to their locations in marginal areas of the range of this species.…”

Section: Discussionsupporting

confidence: 91%

“…This study was conducted in four rivers in Japan, namely the Kaizoko River in Kagoshima Prefecture, the Hatauchi River in Shizuoka Prefecture, the Sanbongi River in Fukui Prefecture and the Nagasawa River in Aomori Prefecture (Figure 1). The Kaizoko and Hatauchi rivers are located within the major recruitment areas of the Japanese eel ( Anguilla japonica ) distribution range, which are close to the Kuroshio Current that transports Japanese eel larvae to East Asia, and the other two rivers are located in the marginal areas that are not close to the Kuroshio Current (Kasai et al , 2021; Yoneta et al , 2019). Consequently, the four rivers were expected to include various wild eel densities.…”

Section: Methodsmentioning

confidence: 99%

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Slower growth of farmed eels stocked into rivers with higher wild eel density

Wakiya

Itakura

Hirae

et al. 2022

Journal of Fish Biology

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Farmed anguillid eels are frequently stocked into natural fresh waters to enhance eel resources, but little is known about what happens to these eels or their interactions with wild eels after stocking. A recent study observed a depressed survival and growth rate of farmed Japanese eels when they were reared with wild eels, which indicated that wild eels might interfere with the survival and growth of farmed-and-stocked eels through intraspecific competition. To contribute to improving eel stocking efficiency, the growth of farmedand-stocked Japanese eels was compared among four rivers with different wild eel densities using mark-and-recapture studies. Based on the 2-year recapture survey after stocking, it was found that the density of the farmed-and-stocked eels was not significantly different among rivers. The daily growth rates of farmed-and-stocked eels in the rivers with lower wild eel density were significantly higher than those of the eels stocked into the rivers with higher wild eel density. The farmed-and-stocked eels moved significantly greater distances downstream than wild eels that showed sedentary behaviour. This and previous studies indicate that significant questions remain about the effectiveness of stocking farmed eels into water bodies where naturally recruited wild eels are present.

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Section: Discussionsupporting

confidence: 91%

Section: Methodsmentioning

confidence: 99%

Slower growth of farmed eels stocked into rivers with higher wild eel density

Wakiya

Itakura

Hirae

et al. 2022

Journal of Fish Biology

View full text Add to dashboard Cite

show abstract

“…Here, we used primers/probe sets targeting 138 bp of the mitochondrial D-loop region. These primers/probe sets have also been used in Kasai et al [ 7 ], where a nationwide eel distribution survey in Japan was conducted. Kasai et al [ 41 ] carefully checked the specificity in the set of primers used in the present study, as follows.…”

Section: Discussionmentioning

confidence: 99%

“…However, the precise spatiotemporal distributions of the eels in various river sites are yet to be established. Today, environmental DNA (eDNA) analyses have been applied in the establishment of eel distribution [ 6 , 7 ].…”

Section: Introductionmentioning

confidence: 99%

Intraspecific genetic variability and diurnal activity affect environmental DNA detection in Japanese eel

et al. 2021

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Environmental DNA (eDNA) analysis with species-specific primer/probe sets is promising as a tool to quantify fish abundance and distribution. Nevertheless, several factors could reduce the accuracy of this method. Here, we aimed to analyze whether intraspecific variability and diel activity rhythm affect eDNA detection in Japanese eels (Anguilla japonica). For this purpose, we performed tank experiments focusing on two points. First, we assessed the effects of base pair sequences with probe region polymorphism on eDNA detection. Next, we evaluated the influences of diel rhythm, activity, and individual differences in eDNA release rate on eDNA concentration. We examined the base pair sequences of the probe regions of 20 individuals and found genetic mismatches in two of them. The eDNA concentration was estimated to be much lower in these variants than it was in the other individuals. We conducted a rearing experiment on four non-variant individuals to explore the influences of diel activity and inter-individual differences in eDNA detection. Nocturnal eel activity was reflected in the eDNA detection but the inter-individual differences remained large. The observed weak positive correlations between eDNA concentration and activity suggest that eDNA emission is highly dependent on basal metabolism. The present study suggests that consideration of polymorphic sites at the probe region and diel activity rhythms should improve the accuracy and precision of abundance estimation through eDNA. Such fine-tuning is applicable not only for eels but also for other fishes to be targeted by eDNA technology.

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“…A subsequent eDNA analysis of water collected from the GIS‐identified potential additional locations, indeed confirmed a previously unrecorded salamander population. In another study, the authors compared the results of their eDNA analysis with simulations of larval transport processes, and modeled them with environmental parameters to identify the factors determining the distribution of a rare eel species (Kasai et al, 2021). In both studies, the habitat requirements of the target species were fairly well‐known.…”

Section: Introductionmentioning

confidence: 99%

Using eDNA presence/non‐detection data to characterize the abiotic and biotic habitat requirements of a rare, elusive amphibian

et al. 2022

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The environmental DNA (eDNA) approach has already been established as a valuable tool for the detection and monitoring of rare and elusive species. However, its application is not limited to assessing whether or not a species is present in a given area. In this study, we collected environmental data from 48 aquatic locations that had previously been investigated in an eDNA‐based study. We sought to determine the abiotic and biotic factors that could explain the presence or non‐detection of Hula painted frog DNA at those locations, in order to characterize this rare species’ little studied habitat requirements. We found that the detection probability of this species decreased substantially with increasing phosphorus loads as well as in the presence of the wetland plant Lythrum salicaria. By contrast, the detection probability increased markedly when Phragmites australis or Ludwigia stolonifera constituted part of the dominant aquatic vegetation. Our results expand the knowledge on this elusive frog species and contribute valuable information for future habitat restoration plans. They further show that eDNA data can also be used to characterize the putative habitats of species where such data are scarce or even totally lacking.

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Distribution of Japanese Eel Anguilla japonica Revealed by Environmental DNA

Cited by 27 publications

References 40 publications

Slower growth of farmed eels stocked into rivers with higher wild eel density

Slower growth of farmed eels stocked into rivers with higher wild eel density

Intraspecific genetic variability and diurnal activity affect environmental DNA detection in Japanese eel

Using eDNA presence/non‐detection data to characterize the abiotic and biotic habitat requirements of a rare, elusive amphibian

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