Honmoroko (Gnathopogon caerulescens), an endangered species endemic to Lake Biwa, is adversely affected by the desiccation of eggs caused by the water level management and deterioration of spawning habitats (lakeshore vegetation zone). Despite a recent study of foreshore spawning of the species having suggested that some local environmental conditions may be related to foreshore...
The pelagic shrimp Lucensosergia lucens, which is also known as “sakura shrimp,” is a small, swimming shrimp that reaches about 4–5 cm in length and is commercially caught mainly in Suruga Bay in Japan. Recently, its catches have declined dramatically, presumably owing to the increased water temperature, the increased predation pressure, and the meandering of the Kuroshio Current...
Macrobrachium rude is a notable freshwater prawn in Bangladesh owing to its palatability and considerable market value. This study examined the reproductive biology of the species for the first time, encompassing sex ratio, size at sexual maturity, reproductive pattern, egg size, and fecundity. A total of 917 individuals were examined, with males ranging from 4.1 to 7.4 mm...
The extensive oceanic life phase of anguillid eels, which occurs far from their freshwater habitats, presents significant challenges in investigating their early life ecology. This is especially true for tropical eel species, which remain largely understudied. In this study we investigated temperature exposure and vertical depth distribution experienced during the newly hatched...
Two large abalone species prevalent in the Japanese archipelago, Haliotis discus discus and H. madaka, are considered to have different morphological characteristics, and previous population genomics analyses have suggested that they have distinct genomic features. However, integrated analyses comparing the genetic and morphological data from these species are lacking; thus, it...
Motile Aeromonas spp., including Aeromonas hydrophila, A. caviae, and A. veronii biovar sobria can cause motile aeromonad disease and pose serious threats to the aquaculture industry. Motile aeromonads showing high minimum inhibitory concentrations (MICs) to widely used various antibiotics in global aquaculture production have been reported. Several studies have shown that A...
“Soggy meat”, which is abnormally softened crushed sardine meat, is often detected in canned sardines seasoned with tomato chili sauce. As soggy meat represents lysed and decomposed tissue, we examined protease activity in the sardine meat during the spawning season. Abnormally soft sardine meat is often found in canned sardine meat from fish caught during the spring and landed...
The invasion and spread of aquatic animal diseases from abroad reduces fisheries and aquaculture production and causes food security issues. If infection spreads to natural populations, it can also cause environmental issues. One measure to reduce such risks is the use of domestic seeds for aquaculture. This study aims to identify consumer preferences for domestic aquaculture...
The tongue serves as a vital organ in mammals, facilitating crucial functions such as mastication, swallowing, vocalization, thermoregulation, and taste reception. Cetacean tongues have evolved under distinct selective pressures compared to those of terrestrial mammals, yet research on their tongues is limited, leading to controversy regarding their gustatory abilities. This...
The physiological impacts of polysaccharides and lipids in seaweed on human health are becoming clearer, but the behavior of the protein components, especially lectins, after ingestion remains poorly understood. In this study, we examined the resistance of edible red algae-derived lectins to digestive enzymes. We found that a lectin extracted from Meristotheca papulosa (MPL-1...
Euryhaline fishes acclimate to various osmotic environments by changing the direction of water and ion transport between body fluids and environmental waters. Ionocytes in the gills are one of the most important cells for the active ion transport. This study aimed to identify the molecules responsible for apical Cl− transport in rainbow trout ionocytes. Tissue distribution and...
The catch of butterfly kingfish Gasterochisma melampus, a large pelagic species in southern temperate waters, is strongly biased (73%) towards females. Whether this is caused by differences in sex-specific spatiotemporal distributions or mortality of sexes is investigated herein. Analysis of sex ratios using a generalized additive model (GAM) for year, month, latitude, longitude...
The hypervariable region (HVR) in the control region of the mitochondrial DNA has frequently been used for population genetics and phylogeographic studies because of its highly variable nature. Although the HVR is beneficial for evaluating recent evolutionary history, including population demography, recent studies have implied the incidence of homoplasy in this region. To assess...
The World Trade Organization (WTO) and European Union (EU) have both put forward tax reforms that impact fisheries’ fuel costs, which are similar in the object of taxation but quite different in the externalities addressed, goals, scope, exemptions or tax rates, creating an opportunity to compare the effects and discuss the alternatives. These proposals are the result of long and...
Tetrodotoxin (TTX), one of the most potent naturally occurring neurotoxins, has been detected in both marine and terrestrial organisms. The marine polyclad flatworm Planocera multitentaculata is known to contain high levels of TTX throughout its life cycle, including in the egg and larval stages. We recently reported that P. multitentaculata from the coastal area of Hayama...