Search

Seasonal changes in habitat use in terms of depth and temperature were estimated for Japanese flounder Paralichthys olivaceus from the Pacific coast of northeastern Japan from 2006 to 2008, using data from trawl and gillnet fisheries logbooks, to which we assigned monthly estimates of bottom temperature. Estimated distributions of flounder for depth and temperature were validated by actual depth and temperature readings from data storage tags (DSTs) attached to flounder, and from collection records by trawl survey. Year-round, flounder > 300 mm in total length were present mainly in areas

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 that isotope ratios were strongly correlated in both. The discrimination models we developed for muscle and collagen proved useful in distinguishing among juvenile P. olivaceus collected from the five prefectures (Aomori, Iwate, Miyagi, Fukushima, and Ibaraki). Juveniles collected in Aomori in particular showed significantly lower values of δ13C and δ15N than those from the other prefectures, which likely reflects the greater influence of the Tsugaru Warm Current in that region. Because collagen in the vertebral centrum can be used to reconstruct annual isotopic records, our results may also assist in developing migration tracking procedures for adult P. olivaceus along the Pacific coast of northern Japan.

A 70-year-old man complaining of pain in his right leg presented to the Department of Orthopedics in our hospital. X-ray findings revealed calcifications around the left kidney. He was referred to our department for further examination. Computed tomography revealed a tumor 3 cm in diameter with calcifications and an obscure border that was located on the caudal side of the pancreas, anterior to the left iliopsoas muscle and at the left side of the aorta. Magnetic resonance imaging showed that the tumor had comparatively low intensity in diffusion-weighted images and the cell density was not high. The contrast of the tumor by enhanced computed tomography was weak, and we had difficulty judging whether the tumor was benign or malignant. Each tumor marker, immunity factor, and hormone-like catecholamine were within the normal range. We considered the retroperitoneal tumor with calcifications as Castleman disease or tumor of nerve origin. It is believed that most retroperitoneal tumors are malignant. We performed laparoscopic surgery to resect the retroperitoneal tumor. Histopathological diagnosis was a primary retroperitoneal venous malformation. Vascular malformation derived from the retroperitoneum is rare. Furthermore, very few cases of venous malformation in the retroperitoneum have been reported.

Here we challenge traditional views on the direction of change in teleost body condition and reproductive traits in response to abiotic and biotic factors by studying the data-rich, planktivorous Norwegian spring-spawning herring (NSSH), a member of the abundant Atlantic herring (Clupea harengus) stock complex. To test potential influential factors, we focused on the last twenty years, i.e. a period with ocean warming, a transient but significant drop in zooplankton biomass, and accelerating interspecific competition resulting from primarily Atlantic mackerel (Scomber scombrus) entering these high-latitude waters in large quantities, “the new mackerel era” in the Nordic Seas. Adult NSSH concurrently allocated relatively less to growth in length than weight resulting in higher body condition. Growth likely decreased in warmer waters under stiff prey competition to support reproductive costs. Condition and reproductive responses were not only immediate but were also lagged by three seasons, corresponding to the period when new oocytes are produced. Furthermore, fecundity increased in warmer waters while egg size dropped. Hence, fine-tuned trade-off mechanisms were apparent and varied. We demonstrate that evaluations of reproductive trade-offs based on pooled data are misleading; poor- and good-condition NSSH followed different reproductive trajectories. These findings emphasize difficult-to-predict trends in life-history traits should be tracked longitudinally by the individuals and their aggregate cohort, as they are linked to complex overarching environmental phenomena, like ecosystem carrying capacity and climate fluctuations. publishedVersion

The temperate seabass Lateolabrax japonicus is a coastal and partial amphidromous fish that is commercially valuable in Japan. Fish age is an important and sensitive variable for stock structure assessment, and inaccurate aging can result in inappropriate management practices. However, there have been few studies on age determination in this species. By examining monthly changes in marginal increment growth, we validated that otolith increments are formed annually. This information was used to develop an age-determination method using otolith sections. Von Bertalanffy growth models were generated based on standard length and weight data for both sexes in Sendai Bay and Tango Bay, Japan. Differences in standard length- and weight-at-age and growth parameters were observed in both sexes and locations. Females exhibited larger standard lengths and weights at older ages than did males, in both locations. Individuals from Sendai Bay exhibited longer average asymptotic lengths, higher asymptotic weight, higher standard length-at-age and higher weight-at-age compared to their counterparts from Tango Bay. Decreases in growth rates in both Sendai Bay and Tango Bay occurred around the age at maturity, indicating that more energy was allocated to reproduction than growth after reaching maturation. Differences between Sendai Bay and Tango Bay in the age at which the maximum instantaneous growth rate and the asymptotic length are reached were thought to arise from differences in water temperature and biological productivity between the two bays.

This paper aims to assess the diel feeding pattern and seasonal variation in the daily ration of immature and mature marbled flounder (Pseudopleuronectes yokohamae ). A day‐night collection by bottom trawls was conducted in Sendai Bay in July 2014. Marbled flounder (131–493 mm total length; Number of collected individuals = 1830, Number of analyzed individuals = 497) fed mainly on polychaetes during the day. At night, stomach content weight decreased with time, but the weight and proportion of bivalve siphons were consistently higher at night than during the day, suggesting nocturnal feeding by the flounder on bivalve siphons. Daily ration was greater in females (, This work was partly supported by the Stock Assessment Program of Fisheries Agency and Fisheries Research and Education Agency of Japan and the program “Project on Clarifying the Impact of Nuclear Substances” of the Fisheries Agency of Japan.

Ontogenetic habitat shift and feeding habits in the shallow (

Following general life history theory, immediate reproductive investment (egg mass × fecundity/body mass) in oviparous teleosts is a consequence of both present and past environmental influences. This clarification questions the frequent use of season-independent (general) fecundity formulas in marine fish recruitment studies based on body metrics only. Here we test the underlying assumption of no lag effect on gametogenesis in the planktivorous, determinate-fecundity Atlantic herring (Clupea harengus) displaying large plasticity in egg mass and fecundity, examining Norwegian summer–autumn spawning herring (NASH), North Sea autumn-spawning herring (NSAH), and Norwegian spring-spawning herring (NSSH). No prior reproductive information existed for NASH. Compared with the 1960s, recent reproductive investment had dropped markedly, especially for NSAH, likely reflecting long-term changes in zooplankton biography and productivity. As egg mass was characteristically small for autumn spawners, although large for spring spawners (cf. different larval feeding conditions), fecundity was the most dynamic factor within reproductive investment. For the data-rich NSSH, we showed evidence that transient, major declines in zooplankton abundance resulted in low fecundity over several subsequent seasons, even if Fulton’s condition factor (K) turned high. Temporal trends in Kslope (K on total length) were, however, informative. These results clarify that fecundity is defined by (i) dynamics of primary (standing stock) oocytes and (ii) down-regulation of secondary oocytes, both processes intimately linked to environmental conditions but operating at different timescales. Thus, general fecundity formulas typically understate interannual variability in actual fecundity. We therefore argue for the use of segmented fecundity formulas linked to dedicated monitoring programs.

The determination of the optimum stocking density of hatchery-reared juveniles in relation to the carrying capacity of the nursery ground is important to the success of any stock enhancement programs. In order to estimate the surplus productivity of nursery grounds available to support hatchery-reared fish, a population growth model for juvenile Japanese flounder Paralichthys olivaceus was developed by extending an ecophysiology-based model on growth of juvenile fishes. Parameters of the model were adjusted using field-collected data from Ohno Bay in northeastern Japan. This model predicted the optimum stocking density, namely the maximum number of hatchery-reared juvenile Japanese flounder released into the bay without decreasing the growth of conspecific wild juveniles owing to food limitation. The optimum stocking density for juveniles of 89 mm total length was estimated to be 2000 individuals per 250,000 m2 in Ohno Bay in 1989. Under the model, the most important factors affecting the optimum stocking density of Japanese flounder were the abundance of mysids and wild juveniles at the time of release. The effect of abundance of a competing flatfish species on growth of wild Japanese flounder was less important.

Stocking hatchery fish into the wild should only be implemented at a level that can be sustained within the available food-based carrying capacity to avoid food resource competition with wild conspecifics. We constructed a simulation model to assess the growth of wild conspecifics under different magnitudes of hatchery fish releases, including no releases and actual release levels, and under different wild fish abundancies. Stocking of juvenile Japanese flounder Paralichthys olivaceus (approximately 70–110 mm TL) in Fukushima from 2003 to 2005 was analyzed. We monitored post-release changes in abundance of both cultured and wild juveniles and their prey (mysids). Our survey and modelled simulations revealed that the surplus prey production was sufficient to support the consumption of stocked and wild Japanese flounder (up to 150,000 individuals per site in 2003 and 2004), during which wild juveniles achieved nearly maximum growth rates. However, in 2005, during which a dominant year class of wild Japanese flounder occurred, the body size of wild juveniles was 49% smaller than the predicted size based on the maximum growth rates. This suggests that the food-based carrying capacity was reached in that year. Thus, it is important to evaluate the existing prey and wild juveniles levels and adjust the release accordingly every year.

The impact of the great tsunami, which was generated by the Great East Japan Earthquake on 11 March 2011, on the quality of a nursery ground for juvenile Japanese flounder Paralichthys olivaceus with a sandy bottom of

Introduction: The objectives of this study were to introduce a newly developed approach for holmium laser enucleation of the prostate (HoLEP) called the “complete en-bloc technique,” and t...

Food web structures are well-studied, central theme of fisheries science that depicts the pathways of energy flow. Researchers have long been studied on the importance of quantitative estimation of the relative contribution of prey animals in fish by stomach contents analysis. However, this analysis requires experienced technique, and it only reflects recent diets. On the other hand, carbon and nitrogen stable isotope ratios representing average feeding habits and trophic position have become a powerful tool in food web analyses. In this study, to clarify the main resources (feeding habits) and contribution rate of prey animals using these two analyses in Sendai Bay. As a result, the feeding habits by stomach content analysis of dominant ten fish species were classified into four groups; fish feeders, crustacean feeders, benthic feeders and plankton feeders. A dual isotope plot of δ13C and δ15N values supported the classification by stomach content analysis. Most of fish feeders depended on bait fishes (mainly feeding on plankton feeders), and crustacean and benthic feeders depended on crustacean and/or benthos. The contribution rate of prey animals by mixing models for δ13C and δ15N within Bayesian framework, Paralichthys olivaceus in June 2012 was 67% Engraulis japonicus, and 32% Ammodytes personatus. The results of stable isotope analysis were well consistent with the stomach contents analysis.

To identify the origin of various fishes and reconstruct their migration history at the individual level, isotope analysis is a powerful alternative to artificial tagging. We used a novel individual-based methodology to reconstruct individual migratory and/or trophic shifts associated with growth based on isotopic data in the vertebral centrum of adult Japanese flounder Paralichthys olivaceus in Sendai Bay. We measured carbon and nitrogen isotope ratios (δ^13C and δ^15N) in muscle tissues, and conducted a segmental isotope analysis of bulk δ^13C (δ^13Cbulk), bulk δ^15N (δ^15Nbulk), and δ^15N of glutamic acid (δ^15NGlu) and phenylalanine (δ^15NPhe) in vertebral collagen. The δ^15NGlu and δ^15NPhe values for bone collagen revealed an increase in trophic position and a shift to lower trophic baselines (δ^15NBase: indicative of δ^15N values of primary trophic sources) for most individuals. For both δ^13Cbulk and δ^15Nbulk, we detected significant positive correlations between values for muscle and the outermost section of vertebral collagen. A nonlinear time-series analysis of δ^13Cbulk and δ^15Nbulk suggested that a combination of intrinsic (the timing of migration from the nursery to deep offshore areas in juveniles) and extrinsic (habitat and/or food qualities) factors influence the isotopic chronology. A segmental isotope analysis revealed the segregation of individuals among sampling sites at all life stages and changes in trophic positions and δ^15NBase values during growth. Our results suggest that the P. olivaceus population in Sendai Bay has both temporal and spatial structure. The temporal structure may be caused by variation in the timing of migration from the nursery to the deep offshore area in juveniles, and the spatial structure may be explained by individual variation in habitat preferences.

The present study aims to clarify the Seasonal bathymetric distributions of three coastal flatfishes (stone flounder, marbled flounder, and Japanese flounder) that are caught mainly by bottom trawls and gillnets off the coast of Fukushima, Japan, by using logbook data. All three species were found to have specific spawning depths, i.e., depths of 40–80 m, 20–40 m, and 10–60 m for stone, marbled, and Japanese flounders, respectively, with extremely high catch-per-unit-effort during their spawning seasons, reflecting spawning ground formation. Furthermore, Japanese flounder showed a tendency to expand their distribution offshore to depths deeper than 100 m after October. These results indicate interspecific variations in migration and aggregation patterns. Using logbook data and considering the seasonal catchability of each fishing gear enabled us to understand the seasonal bathymetric distribution of each species and the depths of their spawning grounds.

To determine the effects of the tsunami on kelp bed communities, we examined two kelp beds that had been surveyed before 2011 on the Pacific coast of Honshu Island, Japan. One survey was conducted in Tomarihama on the Oshika Peninsula, which is dominated by the large perennial brown alga Eisenia bicyclis, and the other survey was conducted in Nagane in Otsuchi Bay, where the large annual brown alga Saccharina japonica var. religiosa dominates. In Tomarihama, the tsunami was associated with a limited loss of E. bicyclis individuals. In contrast, the population of sea urchins, the primary herbivore occurring at high densities, drastically decreased after the earthquake, and a large occurrence of juvenile E. bicyclis was then observed over a broader depth range owing to the decrease in grazing pressure. Some of these juveniles survived to adulthood, and with survival over this extended depth range, the E. bicyclis bed expanded to deeper areas. In Nagane, the biomass of S. japonica var. religiosa displayed no significant change before and after the earthquake. A definite reduction in sea urchins was not observed after the earthquake. Thus, the impact of the earthquake and tsunami widely differed between Tomarihama and Nagane.

Off Fukushima, Japanese flounder (Paralichthys olivaceus) is a highly-valued species supporting coastal and offshore fisheries. We developed an age-structured population model incorporating seasonal coastal-offshore migrations to estimate and predict the abundance of Japanese flounder off Fukushima, where fishing has been restricted since the 2011 Fukushima Dai-ichi Nuclear Power Plant (FNPP) accident. We estimated the abundance of Japanese flounder using catch per unit effort from coastal gill net and offshore bottom trawl fishing from January 2000 to February 2011 and predicted the abundance under two different fishing effort scenarios (the same effort level as 2010 or decreased effort after the FNPP accident). Estimated abundance reflected the seasonal coastal-offshore migrations well, and it was estimated that abundance increased during and after 2007 because of high recruitments. In contrast, it was concluded that the predicted abundance on and after 2012 increased owing to the decreased fishing effort because the same estimated recruits were used in both scenarios. This indicates that the waters off Fukushima have effectively been serving as a marine protected area for Japanese flounder since the FNPP accident. This result was validated because almost all (83%) of the observed abundance index values calculated from a scientific bottom trawl survey during 2003–2014 were included within the estimated (predicted) 95% credible intervals of estimated (predicted) abundance index in the period. We also demonstrated the model's applicability for estimating the optimal fishing effort and age at first landing to maximize the earnings from gillnet and bottom trawl fisheries.

Drifting gill-nets were for a long time the main research gear for investigating the distribution of Pacific saury Cololabis saira. However, it has proven to be difficult to estimate the absolute abundance of saury using drifting gill-nets due to a lack of knowledge on the survey areas swept by these gill-nets. A mid-water trawl stock abundance estimation has the advantage of being able to estimate the absolute stock abundance before the commercial fishing season begins, whereas the conventional stock abundance estimation based on catch per unit efforts of commercial fisheries must be done after the commercial fishing season has ended. To confirm the practicality of a mid-water trawl to estimate the stock abundance of saury, we conducted a comparative survey in the northwestern Pacific Ocean using both a mid-water trawl and drifting gill-nets. We found that the geographic distribution pattern of catch per unit effort for both the mid-water trawl and driftnets was similar. Using the area-swept method and data on the fishing efficiency of the mid-water trawl obtained in a previous study, we were able to estimate the stock abundance plus confidence limits within the research areas. Our results suggest that the size composition of saury sampled by the mid-water trawl can be considered to approximate the actual size composition of saury.

Isotopic compositions of animal tissue are an intrinsic marker commonly used to trace animal origins and migrations; however, few isotopes are effective for this purpose in marine environments, especially on a local scale. The isotope ratio of the lanthanoid element neodymium (Nd) is a promising tracer for coastal animal migrations. Neodymium derives from the same geologic materials as strontium, well known as an isotopic tracer (87Sr/86Sr) for terrestrial and anadromous animals. The advantage of the Nd isotope ratio (143Nd/144Nd, expressed as εNd) is that it varies greatly in the ocean according to the geology of the neighboring continents, whereas oceanic 87Sr/86Sr is highly uniform. This study explored the utility of the Nd isotope ratio as a marine tracer by investigating the variation of εNd preserved in tissues of coastal species, and the causes of that variation, in a region of northeastern Japan where the bedrock geology is highly variable. We measured εNd and 87Sr/86Sr in seawater, river water, and soft tissues of sedentary suspension feeders: the mussels Mytilus galloprovincialis and Mytilus coruscus and the oyster Crassostrea gigas. We also measured concentrations of three lanthanoids (La, Ce, and Pr) in shellfish bodies to determine whether the Nd in shellfish tissue was derived from solution in seawater or from suspended particulates. The εNd values in shellfish tissue varied regionally (−6 to +1), matching the ambient seawater, whereas all 87Sr/86Sr values were homogeneous and typical of seawater (0.7091–0.7092). The seawater εNd values were in turn correlated with those in the adjacent rivers, linking shellfish εNd to the geology of river catchments. The depletion of Ce compared to La and Pr (negative Ce anomaly) suggested that the Nd in shellfish was derived from the dissolved phase in seawater. Our results indicate that the distinct Nd isotope ratio derived from local geology is imprinted, through seawater, on the soft tissues of shellfish. This result underscores the potential of εNd as a tracer of coastal marine animals.

In the original publication, Fig. 1 and legend have been incorrectly published. The correct version of Fig. 1 and legend are provided in this Correction.

We present a case of UPJO associated with an incompletely duplicated collecting system in a horseshoe kidney that was successfully treated by laparoscopic pyeloplasty with concomitant pyelolithotomy. A 53-year-old man had three urological anomalies and urolithiasis. We performed a pyeloplasty and pyelolithotomy using a fully intracorporeal technique. Clinical and radiographic evaluation confirmed complete resolution of the patient’s condition. To our knowledge, there have been no reported cases of UPJO in an incompletely duplicated collecting system with a horseshoe kidney in the same patient. We also provide convincing evidence that laparoscopic pyeloplasty is feasible in complex cases of renal anatomic anomalies.

Ontogenetic habitat shift and feeding habits in the shallow (