Changes in density of under-yearling masu salmon <Emphasis Type="Italic">Oncorhynchus masou</Emphasis> in a natural stream after release

ABSTRACT:   The relation between the density of fish and parameters such as body weight, condition factor and the hepatic triglyceride (TG) content of masu salmon Oncorhynchus masou juveniles after release into a natural stream were studied. Hatchery-reared juveniles of different sizes and numbers were released in May 1999, 2000 and 2001, and investigations were carried out from July to September each year. The density of fish was relatively high in 1999, when juveniles of the largest size and number were released, but then continued to decrease during the investigation. The hepatic TG content remained considerably low in 1999, and there was a significant negative correlation between the density of fish and the hepatic TG content of the juveniles caught over three years. The initial fish size and number at release as well as the nutritional condition of the juveniles may affect the density of fish after release.     

Development of near-isogenic lines of durum wheat (Triticum durum Desf.) for glaucousness inhibitor loci Iw1, Iw3 and Iw4 derived from wild relatives

Genetic Resources and Crop Evolution - The majority of cultivated wheat varieties have glaucous spikes, leaves and leaf sheaths, and the non-glaucous phenotype is rare in modern varieties. The...     

Influence of overplanting paddy rice on irrigation water delivery performance: a case study in the Dakalt branch canal,Nile Delta of Egypt

In the North Nile Delta of Egypt, the impacts of overplanting paddy rice on water delivery performance have not been discussed quantitatively. Further, the amount of water that could have been saved if farmers would follow the planned area is unknown. In this study, water delivery performance was assessed by comparison of actual paddy rice planting and the government’s planned conditions. For both conditions, performance indicators relating to adequacy, equity, and dependability were analyzed across six locations in conjunction with the branch canal water level in 2013 and 2014. Based on the difference between the actual water supply and planned water demand, the amount of water that could have been saved for downstream uses was calculated. The average adequacy for the investigation period was good at one location, fair at 2 locations, and poor at 3 locations in both years. Further, adequacy under both actual and planned conditions was poor in late July at all locations. The planned adequacy and dependability downstream and equity among locations improved compared to the actual condition in both years. Under the condition that paddy rice area is the upper limit planned by the government, about 12.3% and 9.6% of water could be potentially saved in each year. The difference between actual and planned water delivery performance is caused by the branch canal’s low water level. Control of overplanting paddy rice and coordination of water distribution among water user associations would improve stable water level in the canal and, eventually, water delivery performance.

     

Dietary value of benthic diatoms for post-larval abalone <Emphasis Type="Italic">Haliotis diversicolor</Emphasis> associated with feeding transitions

ABSTRACT:   The feeding behavior and growth of post-larval Haliotis diversicolor with initial shell lengths (SL) of approximately 500 μm (Exp. 1-1 and 1-2), 800 μm (Exp. 2), and 1200 μm (Exp. 3) were studied in a laboratory setting while they fed on four species of benthic diatom Achnanthes longipes , Cocconeis sublittoralis , Cylindrotheca closterium , and Navicula ramosissima . Exp. 1-1 and 1-2 revealed no marked differences in post-larval growth rates (mean 24–39 μm SL/day) among the diatom species. However, marked differences in growth rates among the species were revealed in Exp. 2 and 3. Three species, A. longipes , Co. sublittoralis, and Cy. closterium , produced faster growth (Exp. 2 mean 29–51 μm/day, Exp. 3 mean 36–44 μm/day) than N. ramosissima (Exp. 2 mean 18 μm/day, Exp. 3 mean 23 μm/day). Post-larvae fed N. ramosissima had lower digestion efficiency (42.8%) than those fed other diatom species (90.7–100%). Diatom extracellular substances appeared to be principally used from post-settlement to 800 μm SL, and diatom cell contents were required to produce rapid growth of larger post-larvae (>800 μm SL). It is likely that the availability of each diatom for post-larvae was affected by diatom morphology, attachment strength, frustule strength, and post-larval size.     

Evaluating the impact of COVID-19 on ex-vessel prices using time-series analysis

The spread of coronavirus disease 2019 (COVID-19) and subsequent lockdown measures have impacted economies and industries worldwide. The fisheries industry witnessed a sharp decline in demand and a slump in fish prices due to its dependence on the food service industry. It is important to quantitatively assess those fish species affected most and the extent of the pandemic’s impact on them, to take specific countermeasures. We propose a time-series analysis as an alternative to the current practice of using ad hoc year-on-year comparisons. Although the pandemic makes it difficult to construct a counterfactual approach due to the lack of an appropriate control group, we use time-series forecasting to simulate normal conditions using pre-pandemic data. In Tokyo, the unit price of fish species that were negatively impacted by the food services industry dropped by 12.65% to 14.64%, and by 26.08% to 28.22% after the declaration of a state of emergency. Seasonality, short weekly cycles, and short-term market trends are factors that affect the price of fish. Species-specific impact estimates related to the COVID-19 pandemic can allow policymakers to implement recovery measures in a more targeted and effective manner. The results of our analysis can increase fishers’ and policymakers’ awareness of the usefulness of economic analyses and incentivize them to release data to establish a system to accumulate and analyze data strategically for urgent and appropriate interventions in the fisheries industry.

     

Fate and Transport of Nursery-Box-Applied Tricyclazole and Imidacloprid in Paddy Fields

The fate and transport of tricyclazole and imidacloprid in paddy plots after nursery-box application was monitored. Water and surface soil samples were collected over a period of 35 days. Rates of dissipation from paddy waters and soils were also measured. Dissipation of the two pesticides from paddy water can be described by first-order kinetics. In the soil, only the dissipation of imidacloprid fitted to the simple first-order kinetics, whereas tricyclazole concentrations fluctuated until the end of the monitoring period. Mean half-life (DT₅₀) values for tricyclazole were 11.8 and 305 days, respectively, in paddy water and surface soil. The corresponding values of imidacloprid were 2.0 and 12.5 days, respectively, in water and in surface soil. Less than 0.9% of tricyclazole and 0.1% of imidacloprid were lost through runoff during the monitoring period even under 6.3 cm of rainfall. The pesticide formulation seemed to affect the environmental fate of these pesticides when these results were compared to those of other studies.     

Pentachlorophenol-decomposing and PCP-tolerant bacteria in field soil treated with PCP

Soil samples from field plots that had received annual applications of pentachlorophenol (PCP) for 3 consecutive years were analyzed each year for changes in microbial populations, particularly in PCP-decomposing microorganisms and PCP-tolerant bacteria. Within 6 weeks after an initial application of PCP, PCP-decomposing microorganisms increased by about 3 orders of magnitude; this increased population was still observed the following spring. The number of PCP-decomposing microorganisms in the soils that received PCP for 3 yr reached 10⁵· g^?1 soil or more, while that in soils without PCP was 10²· g^?1. The soils that received PCP were not enriched with tetrachlorophenoldecomposing microorganisms. The microbes enriched by PCP may have been bacterial in nature. In 1972 and 1974, the number of PCP-tolerant bacteria increased immediately after PCP application and continued to increase for 2 weeks, then declined. The 1973 data, however, showed no such decline. The number of PCP-tolerant and of crystal violet-tolerant (Gram-negative) bacteria correlated fairly well except at 2 weeks after PCP application (when PCP-tolerant bacteria were more numerous).     

Nonulcerative keratouveitis as a manifestation of Leptospiral infection in a horse

A 2-year-old Thoroughbred filly presented with ocular pain and epiphora of the left eye. The pupil was miotic and the cornea edematous near the ventro-temporal limbus, but did not retain any fluorescein. The topical antibiotics and atropine and diclofenac, and systemic flunixin meglumine and antibiotic therapy did not resolve the condition. A pink and fleshy infiltrate developed near the limbus indicating nonulcerative keratouveitis. The anterior uveitis deteriorated as manifested by the presence of dyscoria, hypopyon, and organized fibrin in the anterior chamber. Ocular signs were improved by topical and subconjunctival corticosteroids, but repeatedly deteriorated as the frequency of medication was reduced. The horse was seropositive to three serovars of Leptospira interrogans. The animal was diagnosed as blind on day 91 by the absence of pupillary light and menace reflexes, and donated for histopathologic diagnosis. The corneal opacity was histologically fibrotic and infiltrated predominantly by lymphocytes with Descemet's membrane partially disrupted by macrophages. The choroid was infiltrated by lymphocytes, eosinophils and basophils, and was positive to IgG and C3. There were filamentous or spiral structures positive to Warthin-Starry stain in the renal cortex. There was also polymerase chain reaction amplification of the leptospiral gene in the kidney. From these findings nonulcerative keratouveitis was believed to be caused by systemic infection with Leptospira.     

Maturity and reproduction of goneplacid crab <Emphasis Type="Italic">Carcinoplax vestita</Emphasis> (Decapoda,Brachyura) in Tokyo Bay

ABSTRACT:     Sexual maturity, morphological sexual dimorphism, and reproduction of the goneplacid crab Carcinoplax vestita were investigated in Tokyo Bay, Japan, from November 2002 to October 2003. The puberty molt in males was evidenced by changes in the relative size of the chelipeds and merus of the walking legs, and was estimated to occur at a size range of 13.20–18.85 mm carapace length. Post-pubertal females were identified by the relative size of the abdomen and puberty was estimated to occur at a size range of 12.81–15.46 mm carapace length. Sexual dimorphism in C. vestita was observed in all features that showed secondary sexual characteristics. Monthly changes of gonad index in males, and of seminal receptacle index and occurrence of sperm plugs in females were synchronized, and indicated that mating was intense in spring. Ovaries began developing in March. Ovigerous females were found in all months except December, but were clearly more abundant between August and October. Fecundity ranged from 7800 to 57 000 mature oocytes per female per batch and was highly correlated with body size. The results suggest that some females may spawn more than one batch per year.