Longitudinal logbook survey designs for estimating recreational fishery catch, with application to ayu (Plecoglossus altivelis)

Longitudinal surveys of anglers or boat owners are widely used in recreational fishery management to estimate total catch over a fishing season. Survey designs with repeated measures of the same random sample over time are effective if the goal is to show statistically significant differences among point estimates for successive time intervals. However, estimators for total catch over the season that are based on longitudinal sampling will be less precise than stratified estimators based on successive independent samples. Conventional stratified variance estimators would be negatively biased if applied to such data because the samples for different time strata are not independent. We formulated new general estimators for catch rate, total catch, and respective variances that sum across time strata but also account for correlation stratum samples. A case study of the Japanese recreational fishery for ayu (Plecoglossus altivelis) showed that the conventional stratified variance estimate of total catch was about 10% of the variance estimated by our new method. Combining the catch data for each angler or boat owners throughout the season reduced the variance of the total catch estimate by about 75%. For successive independent surveys based on random independent samples, catch, and variance estimators derived from combined data would be the same as conventional stratified estimators when sample allocation is proportional to strata size. We are the first to report annual catch estimates for ayu in a Japanese river by formulating modified estimators for day-permit anglers

Settlement behaviour of the early megalopae of the land hermit crab Coenobita violascens (Decapoda: Coenobitidae) under laboratory conditions: Effects of inshore odours and salinity

The distribution of the land hermit crab Coenobita violascens is restricted to the vicinity of rivers,particularly mangrove estuaries. To infer the recruitment mechanisms of C. violascens, we examined settlement behaviour, such as swimming, walking, shell-inspection, and shell-wearing activities, in 0-day-old to 6-day-old megalopae under different seawater conditions: 1) offshore salinity (34 ppt, control), 2) offshore salinity (34 ppt) with inshore odours (riverine water), and 3) inshore salinity (24 ppt). Salinity was regulated using artificial sweater salts. Coenobita violascens megalopae exhibited nocturnal swimming activity, whereas other activities significantly increased during the daytime period. Inshore odours did not affect the swimming and walking activities, whereas the inshore salinity conditions decreased the swimming activity and enhanced the walking activity, i.e., stimulated the settlement behaviour of megalopae. Shell-related activities were not influenced by any of the seawater types. Our results suggest that megalopae might migrate to the coast using nocturnal flood-tide transport and settle on or near inshore habitats under the reduced salinity conditions that occur as a result of the inflow of groundwater and river water. Further studies are required to elucidate the role of inshore odours in the recruitment of C. violascens megalopae in mangrove estuaries

Emigration behaviour, moulting and survival during the sea-to-land transition of land hermit crabs Coenobita violascens and Coenobita rugosus under laboratory conditions: Effects of salinity and riverine odours

Coenobita rugosus is distributed along the entire coast, and the distribution of C. violascens is restrictedto the vicinity of rivers, mainly in the mangrove estuaries on southern Japanese islands. To infer theenvironmental cues affecting successful emigration from the sea to land on these species, we examined shellwearing and landing behaviour, moulting and survival for laboratory-raised megalopae and early juveniles under different seawater conditions: 1) high salinity (34 ppt, control), 2) low salinity (24 ppt), and 3) high salinity (34 ppt) with riverine odours (mangrove riverine water). In C. violascens, reduced salinity and riverine odours stimulated shell-wearing activity, and riverine odours enhanced the landing activity. In C. rugosus, reduced salinity and riverine odours stimulated both shell-wearing and landing activities, and the magnitude of the effects was larger in response to reduced salinity than riverine odours. These seawater conditions also tended to enhance the moulting and survival of the animals. Salinity reductions widely occur along the shoreline due to the inflow of groundwater as well as river water. Riverine odours and reduced salinity should be cues for emigration from the sea to land by megalopae of C. violascens and C. rugosus, respectively, thereby characterizing the distributions of these species on the islands

Distributions of land hermit crabs (Decapoda: Coenobitidae) on the coast of the tidal lagoon, Nagura Amparu, on Ishigakijima Island, Japan.

　We investigated the distributions of land hermit crabs on the coast of the tidal lagoon, Nagura Amparu, on Ishigakijima Island, Japan, through six surveys conducted during the period from October 2011 to September 2013. Nagura Amparu is a brackish estuary system with a tidal flat and mangrove tree areaseparated from the outer sea bay by a sandbank. Land hermit crabs were captured using bait traps at three sites along the shoreline of the sandbank facing the inner tidal flat and at one site in the coastal forest on the sandbank. Four land hermit crab species, Coenobita brevimanus, C. cavipes, C. rugosus, and C. violascens, were collected. Almost all collected crabs were C. violascens, and a few C. rugosus were collected on the shoreline. On the other hand, C. cavipes was dominant, followed by C. violascens, and a few C. brevimanus were captured in the coastal forest. Coenobita violascens were juveniles and adults, and they widely inhabited the shoreline and coastal forest. All C. cavipes were juveniles, suggesting that this species utilizes the coastal forest as a nursery ground. Our results highlight the importance of the Nagura Amparu as habitat for juveniles and adults of C. violascens and juveniles of C. cavipes

Sexual Dimorphism and Reproductive Status of the Red Swamp Crayfish Procambarus clarkii

The red swamp crayfish Procambarus clarkii is native to northeastern Mexico and the south-central USA, and it has expanded its distribution worldwide and negatively impacted the ecosystems in the invaded regions. The dynamics of the P. clarkii populations have been studied as the basis for the development of effective control measures against this invasive alien species. Adult males of P. clarkii exhibit a cyclical dimorphism between two sexual morphotypes; reproductive form I has large chelae and non-reproductive form II has small chelae. However, whether P. clarkii females have two sexual morphotypes and exhibit form alternation has not been resolved, and little is known about the degree of intra-sexual dimorphism of the chelae, even among males. We employed allometric growth analysis on the chelae dimensions of P. clarkii females and males that were collected from a small pond in Yokohama, Japan. Our analysis demonstrated the existence of form I, which has larger chelae, and form II, which has smaller chelae, in P. clarkii females and highlighted the intra- and inter-sexual dimorphisms in the chelae of this species. The reproductive cycle of the population was successfully traced by the reproductive status of P. clarkii based on the occurrence patterns of each sexual morphotype; the form I crayfish occurred throughout the sampling period from April to December, while the occurrences of form I females and males were highly correlated, peaking in October. Our results suggested that alternation of sexual forms occurs in P. clarkii females. The ability to discriminate between the sexual morphotypes based on chelae allometric growth would allow us to evaluate the female reproductive status more easily ansd precisely in invasive P. clarkii populations

Post-load hyperglycemia as an important predictor of long-term adverse cardiac events after acute myocardial infarction: a scientific study

<p>Abstract</p> <p>Background</p> <p>Diabetes mellitus (DM) and impaired glucose tolerance (IGT) are risk factors for acute myocardial infarction (AMI). However, it is unknown whether hyperglycemic state is associated with increased major adverse cardiovascular events (MACE) after AMI. In this study, we evaluated the relationship between glucometabolic status and MACE in patients after AMI, and determined the critical level of 2 h post-load plasma glucose that may be used to predict MACE.</p> <p>Methods</p> <p>AMI patients (n = 422) were divided into 4 groups as follows: normal glucose tolerance (NGT) group, IGT group, newly diagnosed DM (NDM) group, and previously known DM (PDM) group. MACE of the 4 groups were compared for 2 years from AMI onset.</p> <p>Results</p> <p>The NDM group had a significantly higher event rate than the IGT and NGT groups and had a similar event rate curve to PDM group. The logistic models analyses revealed that 2 h post-load plasma glucose values of ≥160 mg/dL was the only independent predictor of long-term MACE after AMI (p = 0.028, OR: 1.85, 95% CI: 1.07-3.21). The 2-year cardiac event rate of patients with a 2 h post-load hyperglycemia of ≥160 mg/dL was significantly higher than that of patients with 2 h post-load glucose of <160 mg/dL (32.2% vs. 19.8%, p < 0.05) and was similar to that of PDM group (37.4%, p = 0.513).</p> <p>Conclusions</p> <p>NDM increases the risk of MACE after AMI as does PDM. Particularly, post-AMI patients with a 2 h post-load hyperglycemia ≥160 mg/dL may need adjunctive therapy after AMI.</p

An R script for unbiased estimation of stocking effectiveness using a two-stage sampling strategy based on fishery landings

The release of artificially produced juveniles is a popular tool in fishery management, with more than 26 billion seeds of 180 marine species released annually into the wild in more than 20 countries. Despite this, there is a lack of research on, and monitoring of, the effects of such stocking efforts in most programs.We aim to improve assessments of the effectiveness of marine stock enhancement and sea-ranching programs using a novel computer program to estimate stocking effectiveness based on a two-stage sampling strategy of fishery landings. We revisit our two-stage sampling method published in 1992 and briefly summarize the estimation procedure using standard literature notations.As an example, we estimate commercial landings of released Japanese flounder (Paralichthys olivaceus), the contribution of released seeds to total commercial landings, and their recapture rate.Contour lines of predicted standard errors of landings and the optimal number of days within survey budget constraints required to sample fish landings per market are estimated.Our method can be applied to any species and case involving two-stage sampling, where all released seeds are marked or tagged, including genetically marked individuals.If the number of individuals that have been released in a sample is known, the stocking effectiveness can be determined with an R script.This program can also be used to determine the optimal sampling strategy.公開日: 2024-02-1