The Japanese eel Anguilla japonica is a prominent and highly valued species in the aquaculture industry in Japan. Sex determination and sex differentiation in eels are significantly affected by environmental factors; however, the molecular mechanisms involved in sex differentiation in eels are largely unknown. In this study, to investigate the gonadal expression profiles of sex-specific genes during

Sepioteuthis lessoniana is a crucial squid species in fisheries and plays a critical role in marine ecosystems. At least two taxa of the squid species have been identified in the waters around Japan; however, the basic biological information of these taxa is limited. In this study, the taxa composition of Sepioteuthis was examined using molecular evidence, and the life-history traits and statolith

To explore the gillnet selectivity for swimming crab Portunus trituberculatus, six mesh sizes (100, 110, 120, 130, 140 and 150 mm) were tested to determine the optimal mesh size for swimming crab. The experiments were conducted in the traditional area for fishing crab in the East China Sea from 25 to 29 July 2018. Four kinds of selectivity curves were used for fitting, and the maximum likelihood method

In this study, the interannual variations of ichthyoplankton assemblages in the Taiwan Strait (TS) during the winters of 2007–2013 were determined. The cold China Coastal Current (CCC) and Mixed China Coastal Water (MCCW) intruded into the TS and impinged with the warm Kuroshio Branch Current (KBC) with annual variations. Consequently, the ichthyoplankton community in the TS was mainly structured into

To elucidate the dynamics of oxidative stress in fish, it is necessary to know the concentration of superoxide anions as a precursor to various reactive oxygen species in the living body. Superoxides are unstable radicals, disappearing within a few seconds, which makes it challenging to measure them using conventional methods. We describe herein the development of a biosensor that can rapidly quantify

Estrogenic endocrine-disrupting chemicals are an increasing social concern, as they can reduce the reproductive activity of wildlife. The present study aimed to clarify the long-term effects of estradiol-17β (E2) on male reproductive activity in goldfish. Sexually mature male goldfish were implanted with a silicone capsule containing E2, and kept for 14 weeks or 15 weeks. The reproductive activity

Our ultimate aim is to establish a small-bodied surrogate broodstock (e.g., mackerel) that produces functional gametes of the Pacific bluefin tuna Thunnus orientalis using xenogeneic germ cell transplantation. To accomplish this goal, we need to be able to sequentially trace transplanted donor cells in recipients. Here we succeeded in identifying two monoclonal antibodies that could specifically recognize

The solitary European sea squirt Ascidiella aspersa was introduced to northern Japan, causing dense coverage of the aquacultured Japanese scallop Mizuhopecten yessoensis. There are concerns that allelopathy by the sea squirt will suppress the growth of the scallop. Herein, we studied the allelopathic and defensive potential of A. aspersa using hemolytic assay. An alkyl sulfate, viz. 3,7,11,15-tetramethyl-hexadecan-1

The cleavage pattern of a vertebrate’s embryo is either holoblastic (complete) or meroblastic (partial). Sturgeon and other basal bony fishes represent a transition of the cleavage pattern. To understand the transition, it is essential to develop an effective technique for the inhibition of specific blastomere cleavage. So far, various studies have demonstrated that diatom-derived polyunsaturated aldehyde

We examined the effects of tank color and stocking density on the growth of spotted halibut (Verasper variegatus) under a green light-emitting diode (LED). Fish reared for 40 days under a green LED (10 μmol m–2 s–1 at the water surface) grew faster than those reared under a white LED, irrespective of tank color (white or black). Green light promoted higher growth than indoor room light when fish were

Cytokines are low molecular weight glycoproteins involved in the regulation of the immune system, and more than 100 cytokines have hitherto been identified in humans. Cytokines similar to those found in humans have also been found in fish. The innate immune response of fish can be examined by using cytokines as markers. We developed a multiplex reverse transcription–polymerase chain reaction assay

Leptocephalus larvae have transparent bodies with tubular intestines that usually lack identifiable food items when they are collected, so mystery has surrounded efforts to determine what they feed on. Artificially spawned and reared first-feeding larvae were found to be highly selective in what they would eat, but they would consume rotifers and eventually ate specially formulated diets that contained

Snow trout Schizothorax labiatus constitute a significant part of the diet of large human population of colder regions of the Indian Himalayan subcontinent, and are also important for local livelihoods there. In the present study, the hematological and serum biochemical parameters of S. labiatus were examined with respect to sex and season. Hemoglobin (Hb) concentration, red blood cell (RBC) count

Bristle patches on the carapace behind the eyes were found for the first time in both males and females of the four species of mud crab Scylla spp. Electrocardiography revealed that the bristle patches of Scylla paramamosain were sensitive to touch (with a glass capillary) but not to chemical stimulation (with sugarcane juice). To elucidate the function of these touch signals, the courtship behaviour

The medaka Oryzias latipes is a teleost fish with an XX/XY sex determination system similar to that of mammals. However, under high-temperature conditions, XX medaka are masculinized by an elevation of the key teleost glucocorticoid, cortisol. Cortisol inhibits female-type proliferation of germ cells and induces masculinization of XX medaka during gonadal sex differentiation. To identify masculinization

Cocaine- and amphetamine-regulated transcript (CART) is an anorexigenic peptide hormone of fish and other vertebrates. In aquaculture, appetite regulation of fish is important to improve their growth. We cloned five CART genes (cart1b, 2a, 2b, 3a, and 3b) from yellowtail Seriola quinqueradiata, which belong to CART groups 1, 2, and 3 across four CART branches according to phylogenetic analysis. The

Two sediment cores were collected from two sites in Nagatsura-Ura Lagoon, the mouth of which was destroyed in the 2011 Tohoku-oki tsunami. Although sediment conditions differed widely between the central and inner parts of the lagoon, we could identify traces of the 2011 Tohoku-oki tsunami at both, and those of earlier tsunamis in the inner part of the lagoon. Chlorophyll a maxima were observed at

Cold-anesthetization waterless live fish preservation is considered a promising alternative strategy. This work investigates the effects of temperature chilling rates of 2, 4, and 6 °C/h on serum biological parameters and muscular chemical composition of channel catfish Ictalurus punctatus and the influence of waterless preservation time (6, 9, 12, 15, and 18 h) on survival after subjection to three

Intensive commercial harvesting of the wedge clam Donax trunculus and the striped venus Chamelea gallina was conducted along the southern coast of the Marmara Sea using a mechanical dredge (MD) and a hand dredge (HD). The purpose of this study was to characterize and quantify the bycatch and discards of both types of dredge. The dredge tows were performed along sandy bottoms at depths ranging from

Pufferfish belonging to Lagocephalus are composed of several species, some of which have been recognized to be non-toxic. Although fish belonging to this genus inhabit a wide variety of seawaters from temperate to tropical, toxin distribution has remained unclear. The present study was conducted to thoroughly survey the presence of tetrodotoxin (TTX) and its analogs (TTXs) in the extracts from various

This study presents age-based life history information on three small-bodied species targeted in the American Samoan fishery: Chlorurus japanensis palecheek parrotfish/fuga-alosama, Lethrinus rubrioperculatus spotcheek emperor/fiola pa`o`omumu, and Naso lituratus orangespine unicornfish/ili`ilia. Age and reproductive information were derived from sagittal otoliths and gonads. Maximum observed ages

The distribution and early growth of juvenile Pacific bluefin tuna (PBF) Thunnus orientalis were studied based on trawl surveys conducted around Sado Island, eastern Sea of Japan, from late August to early September in 2017 and 2018. Juvenile PBF were mainly collected in an area between the Tsushima Warm Current and land where the surface water (5-m depth) temperature ranged from 22.8 to 27.2 °C. The

The effect of fish freshness on myosin denaturation during the frozen storage of flounder muscle was studied. The muscle of instantaneously killed flounder was immediately stored at − 20 °C (pre-rigor mortis; day 0), or after storage at 0 °C for 2 days (rigor mortis) or 5 days (post-rigor mortis). Myosin denaturation in frozen stored muscle was studied by measuring Ca2+-ATPase activity, myosin solubility

Swordtip squid Uroteuthis edulis is a commercially important species in coastal waters throughout the Northwestern Pacific, including those of Japan and Taiwan. Despite the importance of U. edulis to fisheries, previous studies on the life history traits (growth rate, size at maturity, and fecundity) of its populations in the Northwestern Pacific have been localized and region specific. Thus, we report

We examined phytoplankton productivity in Shido Bay, an active oyster farming area in the eastern Seto Inland Sea, Japan, by an in situ 13C method from March 2016 to January 2017. The depth-integrated daily phytoplankton production ranged from 0.13 to 1.61 g C m−2 day−1, and the estimated annual production was 218 g C m−2 year−1. The daily production peaked in the rainy season and autumn, when phytoplankton

Globally, neonicotinoid contamination in aquatic environments, including estuarine areas, is a prevailing environmental concern. The estuarine resident marine crustacean sand shrimp Crangon uritai was previously found to have a higher tolerance to neonicotinoids than the marine crustaceans kuruma prawn Penaeus japonicus and mysid Americamysis bahia. Based on these findings, we aimed to explore the

Gene expression profiles during the transition from fasting to refeeding were investigated in the gut and liver of Masu salmon Oncorhynchus masou masou. Fish were starved for 3 days and then fed at 3% of body weight. The gut and liver were resected before and after feeding, and the tissues were used for transcriptome analyses. Twenty-nine and 45 genes were more than eightfold differently expressed

Increasing water temperatures and salinity intrusion due to climate change are serious challenges for freshwater aquaculture. In this study, we assessed the combined effects of salinization at 0, 6, and 9‰ and water temperatures of 28, 31, and 34 °C on the survival and growth rates, and feed utilization, of freshwater snakehead Channa striata. We also assessed feed digestibility in snakeheads to explore

Generally, the catch efficiency (CE) of a set net is difficult to evaluate because it is affected by fish behavior. Therefore, to evaluate CE, we proposed a fish school behavior simulation model based on the boid model and applied it to a full-scale set net. The moving path of the fish school around the set net was simulated and visualized via the proposed method. From the moving path, three behaviors

We reviewed the current methodology and practices of the DNA metabarcoding approach using a universal PCR primer pair MiFish, which co-amplifies a short fragment of fish DNA (approx. 170 bp from the mitochondrial 12S rRNA gene) across a wide variety of taxa. This method has mostly been applied to biodiversity monitoring using environmental DNA (eDNA) shed from fish and, coupled with next-generation

Hypo-salinity exposure is a serious concern for bivalve aquaculture, with profound effects on the animals’ physiological condition. The present study aimed to evaluate the influence of low-salinity exposure on the clearance rate, total heterotrophic marine bacteria and total Vibrio count in flesh, as well as the biochemical parameters of hemolymph and heat shock protein (HSP) gene expression, in Pinctada

The proximate composition and nutritional content of oysters define their quality and commercial value. Cultivation site and harvest date may impact these characteristics. We assessed moisture, ash, protein, fat, and glycogen concentrations, mineral and free amino acid content, and free fatty acid composition in oysters Crassostrea gigas from three coastal regions of the Seto Inland Sea, Hiroshima

Although recreational fishing is popular in Japan, few estimates have been made of its economic value to the country. This study aims to (1) evaluate the economic value of recreational fishing in Tango Bay, Kyoto Prefecture using the travel cost method (TCM); and (2) explore the development of related regional economies around Tango Bay. The TCM analysis showed that 150,000 anglers visit Tango Bay

The feeding habits and prey selection of Gymnocypris firmispinatus in the Anning River were investigated with respect to fish size, season and sex. Gut contents of 305 individuals ranging in size from 57 to 193 mm total length were analyzed, and 16.0% of the guts were found to be empty. The vacuity index indicated that the feeding intensity of the fish roughly followed a seasonal trend, with minimum

We examined the sea-entry conditions (i.e., timing and body size) of juvenile chum salmon that improve their survival during their coastal residency. On 25 June 2013, we sampled 365 juvenile chum salmon [57.5–98.6 mm fork length (FL)] off Konbumori, eastern Hokkaido, ⁓ 20 km east of the Kushiro River mouth, which originated from a hatchery in the Kushiro River. Sea-entry conditions of these Konbumori

Gelatin, which is thermally converted from collagen, is widely utilized in the pharmaceutical industry as a raw material for hard and soft capsules. The aim of this study was to produce gelatin from yellowfin tuna skin, the by-product of tuna processing, and determine the optimal concentration for hard capsule production. Capsules were prepared from the skin gelatin. The tuna skin gelatin was characterized

The aquaculture industry is growing rapidly throughout the world, but due to intensification, fish hatcheries are often faced with infestations of parasites, which can lead to economic loss. Among these parasites, the leech Zeylanicobdella arugamensis (Hirudinea: Piscicolidae) has been reported to impact hybrid groupers and other hosts. The objective of this study was to test the antiparasitic potential

The goldfish Carassius auratus is a gonochoristic fish, but heterotypic sexual behavior can be induced by hormonal treatment in both males and females. Olfaction is essential for gender-typical sexual behavior in both male and female goldfish. Males have a stimulatory olfactory pathway for their sexual behavior. Female sex pheromones elicit male-typical sexual behavior in males. Olfactory blockage

This study was undertaken on three species of rabbitfish, Siganus puellus, Siganus unimaculatus, and Siganus virgatus, to clarify whether stonefish toxin-like toxins are distributed in rabbitfish. The primary structures of toxins from these three species of rabbitfish were successfully elucidated by complementary DNA cloning and found to comprise two different subunits with almost the same molecular

In this study, we cloned the ATP-binding cassette (ABC) subfamily G member 2 gene (Abcg2 gene; breast cancer resistance protein) from the liver of the marine pufferfish Takifugu rubripes, and examined its tissue distribution and gene structure. The full-length complementary DNA (cDNA) was 1977 base pairs (bp), comprising 15 exons in chromosome 17, and was assigned to the teleost Abcg2b paralogue. The

Japanese dace Tribolodon hakonensis rearing experiments were conducted to estimate parameters related to 137Cs uptake and excretion processes. Fish (initial mean total length 256 mm, 136 g) were reared at 20 °C for 182 days using the same daily ingestion rate (1% of body weight for 6 days per week) with three feeding regimens: feeding contaminated pellets (80.7 Bq/kg-dry of 137Cs) throughout the experiments

The reproductive biology of a commercially important sparid, the goldlined seabream Rhabdosargus sarba, was determined from examination of 802 specimens (443 females, 232 males, 68 fish of undifferentiated sex, and 59 bisexual fish) collected by fisheries operating in the central waters of the Taiwan Strait (henceforth “central Taiwan Strait”) from January to December 2016. Previous studies undertaken

The distribution of salmon roe poses a risk to the salmon industry due to the potential transmission of quarantinable disease-causing pathogens. The curing of commercial salmon roe with saturated saline or soy sauce seasoning is widespread in Japan. The aim of this study was to evaluate the effect of commercial curing processes on quarantinable disease-causing pathogens [Aeromonas salmonicida, Renibacterium

The effects of water temperature during the non-spawning season (yolkless to early yolk formation stage of the ovary) on the growth and reproductive characteristics of 4-year-old hatchery-reared walleye pollock Gadus chalcogrammus (repeat spawners) were examined. Fish were kept in tanks under two temperature regimes (non-controlled: 6.4–17.2 °C; cooled: 5.1–15.7 °C) from 42 to 46 months post-hatching

In our previous study, kamaboko was fermented in koji to prolong its shelf life and to increase its health-promoting effects. After fermentation, the texture of the kamaboko became cheese- or tofuyo-like. In the present study, sauces were produced by the fermentation of kamaboko in fermentation beds of wheat (WS), rice (RS), brown rice (BS), or soybean koji (SS), and their sensory qualities examined

Thermally selected male rainbow trout selectively bred at high temperatures were crossed with females of the Nikko strain with normal thermal tolerance. The F2 pedigrees, comprising 1641 individuals, were divided into 26 batches. The fish were acclimated to 17 °C, then their thermal tolerance determined by measuring the effective time (ET) required for them to lose equilibrium at an approximate upper

Fish and marine invertebrates constitute an important part of the human diet worldwide, and their muscles are the major edible parts. The muscles are a rich source of proteins, which in other terms determines the nutritional value and the quality of seafood products. Though the fish skeletal muscle proteins share many similarities with their mammalian counterparts, there exist great differences in

Cholecystokinin (Cck) and peptide YY (Pyy) play important roles in digestive regulation in fish, but their function in red seabream (Pagrus major) remains obscure. Two cck complementary DNAs (cck-1 and cck-2) in red seabream were identified, and tissue distribution analysis of the genes revealed that cck and pyy were expressed throughout the digestive tract, except for stomach cck-2. After feeding

Fish that display schooling and social behaviors are expected to show stress responses when they are challenged by isolation. Medaka exhibit social behavior in group situations, but little is known about the effects of social isolation on their physiological stress responses. Here, we subjected male medaka to several different housing situations and assessed whether the stress responses differed between

We analyzed the bacterial flora and chemical properties of the Japanese traditional anchovy product called salted Etari, which is distributed in Nagasaki Prefecture in the western part of Japan. The pH and NaCl concentrations ranged from 6.4 to 6.6 and from 9.6% to 13.9%, respectively. The lactic acid and total free amino acid concentrations were determined to be between 122 and 344 mg/100 g of sample

This study assessed the effects of diets supplemented with different types of chitin hydrolysate on larval growth of the Japanese eel Anguilla japonica. Larvae were reared for 26 days on artificial diets containing 2% of purified monomeric N-acetylglucosamine (NAG1), a mixture of mono-, di- and trimers (NAG3), a mixture of mono-, di-, tri-, tetra-, penta- and hexamers (NAG6), or a control diet. The

The aim of this study was to evaluate the effects of the antioxidant astaxanthin on the immune response, growth, and reproduction of the crayfish Procambarus clarkii (Girard, 1852) stressed with the toxin microcystin-leucine-arginine (MC-LR). P. clarkii exposed to MC-LR were treated with one of four concentrations of dietary astaxanthin supplement (0, 2.5, 5, or 10 mg/g) for 36 consecutive days in

There are two types of movement pattern in the Brachionidae (rotifers), swimming and attachment, although the factors that induce a shift between them have not been adequately clarified. This study investigated the effects of five external factors—food limitation, temperature, salinity, predator, and un-ionized ammonia—on movement in females of the euryhaline rotifer Brachionus plicatilis sensu stricto

We aimed to determine the spawning period of black sea bream Acanthopagrus schlegelii in Hiroshima Bay, Japan, based on the distribution of its eggs, to assist in the resource management of this species. We developed a monoclonal antibody assay for the identification of black sea bream eggs, and appraised its specificity using immunohistochemical staining and DNA barcoding. To estimate the black sea

To test whether stable isotope ratios of carbon (δ13C) and nitrogen (δ15N) can be used to understand the ecological connectivity of Japanese flounder Paralichthys olivaceus, we evaluated the isotopic signatures of juvenile P. olivaceus from the Pacific coast of northern Japan (i.e., from Aomori to Ibaraki Prefectures). We measured δ13C and δ15N in muscle and collagen extracted from vertebrae and found

Artificial interspecific hybrids (3n) of tetraploid dojo loach Misgurnus anguillicaudatus (TTTT) and diploid large-scale loach Paramisgurnus dabryanus (PP) were viable. Allopentaploid loaches (TTTTP) were produced by cold-shocking the fertilized eggs of TTTT females fertilized with sperm of PP males. The TTTTP were viable and well developed. As there are currently no reports on the fertility and gamete

Tidal flats are ecologically important as they support a large community of animals (e.g., crabs, mollusks, and polychaetes) and restore water quality. However, information regarding microbial eukaryotes, most of which are protists, associated with animals inhabiting these environments is limited. In the present study, utilizing polymerase chain reaction techniques, we detected fragments of the small

Complementary DNA encoding a part of myosin heavy chain was cloned from fast skeletal muscle of Japanese codling Physiculus japonicus. Japanese codling, a frequent catch off the Pacific coast of northeastern Japan, is a typical underutilized fish species, especially in summer. Phylogenetic analysis of the deduced amino acid sequence of Japanese codling myosin heavy chain loop 2 region revealed that

Many scleractinian corals only spawn once a year, so opportunities for collecting their gametes are limited. Consequently, the induction of spawning in coral would be useful, not only for studies on the mechanisms of coral reproduction, but also for stock enhancement. A spawning-induction method using hydrogen peroxide (H2O2) has already been developed for coral, but most adult corals died after exposure

Larvae of Auxis rochei and Auxis thazard are commonly found in tropical to temperate waters around the world; however, their identification is difficult due to their similar morphological characteristics. In order to determine the morphological differences between larvae of these two species, we identified larvae of 192 A. rochei and 119 A. thazard using species-specific genetic markers and compared