Circadian changes in serum concentrations of testosterone (T), 11-ketotestosterone (11KT), estradiol-17β (E2), 17α,20β-dihydroxy-4-pregnen-3-one (DHP), 17α-hydroxyprogesterone (OHP), cortisol (F) and progesterone (P) were investigated the spermiated/ovulated Japanese char Salvelinus leucomaenis for over three days using newly developed time-resolved fluoroimmunoassays. Testosterone DHP both sex 11KT male showed significantly (P<0.05) higher levels just before/after onset darkness (15:00 or...

Abstract The use of traditional in situ methods for underwater surveys to map freshwater mussel habitats is limited by challenges such as water transparency, depth and high labour demands. In this study, adaptive resolution imaging sonar (ARIS) was applied monitor distribution abundance. contrast conventional quadrat surveys, acoustic survey non‐invasive enables direct observation mussels allow their survival status be determined turbid water. ARIS produces high‐quality images that...

Freshwater mussels have often been used as indicators of a trophic baseline (i.e., primary consumers) in the food web. To assess utility large filter-feeding mussel, Cristaria plicata, an isotopic indicator, we compared carbon (delta C-13) and nitrogen N-15) stable isotope ratios mussel with those its potential sources, particulate organic matter (POM) sediment (SOM). The delta C-13 values (shell length > 140 mm, -31 parts per thousand to -29.2 thousand) were similar POM (-30.2 rather than...

The life history and reproductive ecology of an autumn-spawning bitterling Acheilognathus typus were studied under natural experimental conditions. In the study pond, embryos A. emerged from mussels in May grew rapidly until August, whereas overwintered age-1 fish slowly. Adult pond was smaller (32-47 mm standard length) than they other habitats mainly spawned mussels. number negatively correlated with shell length mussel, a lower observed larger (over 110 length). mussel size-choice...

In this study, we try for fish classification using high resolution acoustic video camera at 3.0 MHz center frequency (ARIS). Newly observation method with wide in vertical and narrow horizontal beam (WVNHB) was proposed getting quality image of swimming fish, tested an processing algorithm basing on Normalized Cross Correlation (NCC) classification. This high-frequency applied to the first time. Using method, successfully obtained images performed images.

Digging is necessary to detect plant roots under the water bottom. However, such detection affected by transparency of and working skills divers, usually requires considerable time for high-resolution sampling, always damages survey site. We developed a new automatic non-destructive acoustic measurement system that visualizes space bottom, tested in situ natural roots. The mainly comprises two-dimensional waterproof stage controlling unit unit. was electrically controlled through notebook...

Genotyping of endangered species is helpful for establishing and evaluating conservation strategies. Mitochondrial sequence data was analyzed from 541 individuals a critically fish, Acheilognathus typus present-day range-wide localities to re-evaluate an in-progress restoration program around Lake Izunuma-Uchinuma, Miyagi, Japan. showed low diversity with only eight haplotypes π ĥ values 0.59129 0.00118 respectively. Genetic suggests A. adapted pulsed environments prone population flush...

The trophic positions of top predators can provide useful information for estimating the length food chains and assessing impacts invasive species or bioaccumulation harmful compounds. In aquatic ecosystems, large carnivorous fishes may change their ontogenetically. We used stable carbon nitrogen isotope ratios to test hypothesis that largemouth bass, in Lake Izunuma, Japan, would increase with total (TL) as a result ontogenetic shifts diet. Results from analysis R mixing model indicated...

A new observation method of fish classification by using acoustic video camera (ARIS) at 3.0 MHz center frequency was developed. Using the method, high-quality image obtained. After getting ARIS, we utilized a called Scale-Invariant Feature Transform (SIFT) <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">[1]</sup> into instead that used before, which is Normalized Cross Correlation (NCC) xmlns:xlink="http://www.w3.org/1999/xlink">[2]</sup> , and...

Both adult females and males of Argulus mongolianus Tokioka, 1939 were collected from the buccal cavity wall body surface freshwater fishes in Lake Izunuma Uchinuma, Miyagi Prefecture, northen Honshu, Japan. The original description species was insufficient, based on a single female Inner Mongolia, China, no further has been made to date. Thus, this paper redescribes A. newly-collected specimens, including first male. This represents record infected largemouth bass, Micropterus salmoides...

Due to water transparency, depth, and higher labor demand, conventional methods for the underwater survey (e.g., optical sensing quadrat survey) have their limitations. Thus, overcome these barriers, this paper proposes a method of acoustic which uses high-resolution video camera-ARIS visualize lake bottom investigate distribution mussels. Newly produces near-video quality images constructing map by Image Mosaic Operation, can be helpful assessing status Convolutional Neural Network(CNN)...

We examined whether small omnivorous fishes (smaller than ~100mm long) integrate littoral, pelagic and benthic pathways in a shallow, eutrophic lake (Lake Izunuma, Japan). The surface of the was covered by dense vegetation floating-leaved macrophytes, species dominated icthyofauna. determined δ13C δ15N ratios five dominant fishes. Using stable isotope analysis R mixing model, we possible contribution three potential food sources (epiphytic algae, zooplankton zoobenthos (larval chironomids))...

淡水魚は海水魚よりも放射性セシウムを蓄積しやすいと考えられている．しかし成長段階に応じた蓄積については，十分に明らかになってはいない．そこで本研究では，オオクチバスMicropterus salmoidesによる放射性セシウムの蓄積様を明らかにすることを目的として，成長段階ごとの放射性セシウム濃度を測定し，セシウム137／カリウム40比についても検討した．セシウム137濃度は孵化により低下し，摂餌開始により上昇した．1個体あたりのセシウム137蓄積量は，孵化後6ヶ月間で8.6×102倍となり，成長に伴う摂餌の開始と食性の変化が放射性セシウムの蓄積に寄与している可能性が示唆された．

In the present paper, we describe development of an α-ray imaging detector based on a ZnO single crystalline scintillator and position-sensitive photomultiplier tube (PSPMT). The crystal was grown by hydrothermal synthesis method with 2-inch-φ in diameter. specimen polished out to be 0.5 mm thickness. After optically coupling PSPMT, irradiated <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">241</sup> Am for evaluation both spatial resolution...

In ecological research, accurately collecting spatiotemporal position data is a fundamental task for understanding the behavior and ecology of insects other organisms. recent years, advancements in computer vision techniques have reached stage maturity where they can support, some cases, replace manual observation. this study, simple inexpensive method monitoring three dimensions (3D) was developed so that their could be observed automatically experimental environments. The main achievements...

オオクチバスとブルーギルは,日本各地に移殖された外来魚で,ため池はその主要な生息場所となっている.本研究では,オオクチバスおよびブルーギルのため池からの用排水路を通じた移出状況を調査した.私たちは宮城県北部に位置する照越ため池の用水路と排水路に,ため池から流出した魚類を捕獲するトラップを設置した.4 月下旬から 7 月下旬の調査期間中,これらの外来魚は用水路と排水路の両方から何回も流出しており,その流出のタイミングは,それぞれの水路の通水期間に限られていた.体長 125 mm の成魚のブルーギルも流出していた.ため池の魚類生息数を池干しによって調査した結果,ため池に生息する外来魚のうち,オオクチバスは 4. 0%,ブルーギルは 7. 1%が流出していたことが示された.外来魚の流出は繰り返し生じ,生息個体数の数%が流出していたことから,外来魚の流出は稀な現象ではなく一般的な現象である可能性が高い.この結果は,ため池が下流域への外来魚供給源となっていることを示す.周辺地域への被害拡大を防ぐためにも,ため池の外来魚の駆除は重要だと言える.