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

The neurotoxin domoic acid (DA) is produced by Pseudo-nitzschia spp. during harmful algal blooms and is linked to amnesic shellfish poisoning. This toxin is particularly problematic in the culture of bivalves for human consumption. In this study, we exposed bay scallops to 20, 40, and 60 ng/ml DA and examined toxin accumulation and stress response at 3, 6, 12, 24, 36, and 48 h of exposure. Oxidative

Cytochrome P450 1A (Cyp1a) catabolizes polycyclic organic compounds. In this study, we sequenced the cyp1a gene from two Javanese medaka Oryzias javanicus strains and examined gene expression in response to two organic pollutants, phenanthrene and pyrene. Sequence comparisons among the two strains identified several single-nucleotide polymorphisms (SNPs), two of which resulted in amino acid substitutions

We investigated the effects of different heating conditions on the texture and extractive compounds of meat derived from each part of the yellowtail Seriola quinqueradiata fish. Heating conditions had a tendency to affect the hardness and sample thickness of the dorsal ordinary muscle (OM) and dark muscle (DM). Heating did not significantly affect the inosine monophosphate level in OM. However, lo

Predicting the outbreak of disease is essential when managing shrimp farms. Acute hepatopancreatic necrosis disease (AHPND) caused by Vibrio parahaemolyticus is a serious disease in shrimp. It is essential that shrimp farmers on the east coast of the Mekong Delta detect the disease as early as possible, because the mortality rate can reach 100%. Here, we used machine learning to predict AHPND development

We investigated the free amino acid (FAA) composition, glycogen content, and body index of 31 brands of oyster Crassostrea gigas to evaluate their taste graphically using a three-dimensional (3D) graph. Taurine was the most abundant FAA, followed by glutamic acid, glycine, alanine, and proline. Based on the sensory evaluation, oysters with a higher glycogen content were more often evaluated as “sweet”

The suitability of fermented products of Ulva fronds as diets for juvenile asari clams was tested. Ulva fronds were transformed by fermentation into a single-cell product (Ulva marine silage; UMS) of suitable size for ingestion by the clams. No dietary effect was seen in clams fed UMS alone. Furthermore, combined feeding with UMS and Chaetoceros calcitrans, which is considered a suitable diet for clams

Chondroitin sulfate synthase-1 (ChSy-1) plays an important role in the synthesis and chain extension of chondroitin sulfate (CS). CS, a linear polysaccharide with high structural diversity, plays crucial roles in cell adhesion, morphogenesis and cell division in response to viral and bacterial infections. However, the role of ChSy-1 in the immune response remains unknown. In the present study, ChSy-1

The activity of proteases may be lost during microquantification because of their nonspecific binding to tubes and pipette tips. In this study, the effects of blocking reagents (blockers) in dilutions of digestive proteases of yellowtail, Seriola quinqueradiata, were compared. EzBlock Chemi (EBC; protein free), Western BLoT Blocking Buffer (WBB; protein free), casein-based blocker, and bovine serum

Fermentation of kamaboko in koji with wheat (KW), rice (KR), brown rice (KB), or soybean (KS) was performed by simulation of tofuyo processing. Moisture and protein content decreased with fermentation, while other detected compounds increased significantly. Ash content increased from 12.9 g/100 g in kamaboko to 17.9–20.2 g/100 g (KW, KR, and KB) and 26.8 g/100 g (KS) after 4 weeks of fermentation.

In order to study the effects of carbon source addition on the bacterial community, water quality and shrimp growth in the recirculating aquaculture system of Litopenaeus vannamei, sucrose with 50% of the daily feed was added daily to the system from the middle stage of culture. The bacterial communities in biofilters, aquaculture waters and shrimp intestines were measured using an Illumina MiSeq platform

To investigate the species composition and genetic characteristics of Far Eastern daces, genus Tribolodon, in the Tama River, Japan, partial DNA sequences of the mitochondrial DNA control region were compared among specimens from the whole river system. Specimens of Tribolodon hakonensis (n = 257) and Tribolodon brandtii maruta (n = 193) were examined in this study. Inconsistencies in species identification

Koji is commonly used in manufacturing Japanese fermented products and promotes enzymatic degradation. In recent years, a seaweed koji has been developed by culturing Aspergillus oryzae on nori Pyropia yezoensis. In the present study, we prepared nori koji by culturing A. oryzae on high- and low-quality noris and then mixing this preparation with additional dried nori. Suitable fermentation conditions

The objective of this study is to determine the lipid content and fatty acid composition of Anguilla japonica caught in South Korea. Seventy-nine eels caught at four different locations in different seasons were analyzed. Lipid content (1.3–30.0% of muscle weight) was more affected by season than by the location where the fish were caught, being the highest among the eels caught in May. Lipid content

Amino acids can act as signaling molecules in protein synthesis and animal growth by regulating several genes in the target of rapamycin (TOR) pathway. An 8-week feeding trial was conducted to examine the effects of dietary proline on growth performance, body composition, amino acid profiles, blood-biochemistry and expression of TOR pathway-related genes in juvenile Nibea diacanthus. Fish (450 juvenile

The article “Bio‑economic analysis of super‑intensive closed shrimp farming and improvement of management plans: a case study in Japan”, written by Junpei Shinji, Setsuo Nohara, Nobuyuki Yagi and Marcy Wilder was originally published electronically on the publisher’s internet portal on 17 September 2019 without open access.

The article “Geographical variation in spawning histories of age‑1 Pacific saury Cololabis saira in the North Pacific Ocean during June and July”, written by Satoshi Suyama, Hitomi Ozawa, Yasutoki Shibata, Taiki Fuji, Masayasu Nakagami and Akio Shimizu was originally published electronically on the publisher’s internet portal on 27 March 2019 without open access.

The article “Development of an efficient bioreactor system for delivering foreign proteins secreted from liver into eggs with a vitellogenin

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The microbiological properties of Myanmar traditional fermented products were characterized using four different brands of bottled shrimp sauce products sold frequently at a large grocery market. Viable cells of these products were detected at various levels (102–105 cfu/ml) using de Man, Rogosa and Sharpe (MRS) agar medium containing 10% NaCl, and all isolates from the product samples were identified

The environmental DNA (eDNA) technique is a convenient and powerful tool to detect rare species. Knowledge of the degradation rate of eDNA in water is important for understanding how degradation influences the presence and/or estimate biomass of aquatic animals. We developed a new set of species-specific primers and probe to detect eDNA of Japanese eel Anguilla japonica, which is a commercially important

The interaction between cortisol and aromatase may be a critical factor in sex determination or sex changes in teleost species. High cortisol concentrations inhibit transcription of the aromatase gene, resulting in masculinization. Anemonefish (Amphiprion spp.) are socially controlled, protandrous sex-changing fish, with a monogamous mating system. Females are the largest and most dominant members

Kisspeptin is an endogenous ligand that modulates gonadotropin-releasing hormone (GnRH) secretion and plays an essential role in the reproduction of mammals. In fish, two subtypes of kiss genes (kiss1 and kiss2), which encode kisspeptins, have been reported. Our previous study showed that kisspeptin 2 receptor (KissR2) is highly expressed in the vicinity of GnRH1 neurons, and that centrally administered