Search

Objective: Coho Salmon Oncorhynchus kisutch provide an important resource for recreational, commercial, and Indigenous fisheries in the Pacific Northwest. The goal of this study was to improve our understanding of how marine mammal predation may be impacting the survival and productivity of Coho Salmon in the Strait of Georgia, British Columbia. Specifically, we quantified the impact of harbor seal Phoca vitulina predation on juvenile Coho Salmon during their first several months at sea. Early marine survival is believed to be the limiting factor for the recovery of Coho Salmon populations in this region. Methods: To estimate the number of juvenile Coho Salmon consumed by harbor seals, we developed a mathematical model that integrates predator diet data and salmon population and mortality dynamics. Result: Our analysis estimated that harbor seals consumed an annual average of 46−59% of juvenile Coho Salmon between 2004–2016, providing the first quantitative estimate of seal predation in the Strait of Georgia. Conclusion: Marine mammal predation on juvenile Coho Salmon is potentially a very important factor limiting survival and recovery of Coho Salmon in the Strait of Georgia. Impact statementCoho Salmon populations in the Strait of Georgia have experienced precipitous declines in marine survival over the last four decades. In this study, we used predator diet data to quantify the potential impact of harbor seals on juvenile Coho Salmon. Our results suggest seal predation may strongly influence survival of young salmon during their first several months at sea, and should be considered in future recovery efforts. [ABSTRACT FROM AUTHOR]

Pinniped populations around the world increased rapidly after hunting and culling during the nineteenth and twentieth centuries ended. Some believe that pinnipeds are now preventing the recovery of certain fish populations, and that controlling pinniped population abundance using lethal measures such as harvesting or by non‐lethal means like contraception could recover fish populations. It is unclear, however, how effective and how long it would take for such methods of population control to bring numbers of pinnipeds down to target levels. We used sex‐ and age‐structured population models to estimate how quickly harbor seal (Phoca vitulina) abundance in British Columbia, Canada, could be reduced by 50%, through combinations of lethal removals and sterilization of adult females. Models were fit to seal abundance, demographic, and harvest data collected between 1879 and 2014. Simulation modeling suggests reliance on contraception exclusively is unlikely to reduce the current harbor seal population (numbering ~100,000) by 50% within 25 years, and would result in more variable outcomes, compared to lethal removals. Contraception could be combined with harvesting to maintain a target abundance of harbor seals (although captive studies with harbor seals are needed to confirm the efficacy of contraception). Our simulation modeling approach provides a useful framework to assess how non‐lethal measures could be integrated into policies that promote active population control of harbor seal numbers. [ABSTRACT FROM AUTHOR]

The commercially, recreationally, and culturally important Fraser River Sockeye Salmon Oncorhynchus nerka has experienced a productivity decline over the past 3 decades, which—along with greater temporal variation in annual abundance (i.e., cyclic dominance)—may at least partly be due to Steller sea lion Eumetopias jubatus (SSL) predation on returning adult salmon. This assumes that SSLs residing around northern Vancouver Island (British Columbia, Canada) target Sockeye Salmon for just a few weeks during the peak of their run. It is a reasonable enough assumption to warrant immediate priority for field research on SSL behavior and diets during the migration period. We evaluated the plausibility of the assumption with a variety of approaches ranging from simple estimates of maximum SSL consumption to partitioning of observed marine mortality rates and analysis of SSL foraging behavior to show that SSLs could have caused the decline in productivity and abundance of Fraser River Sockeye Salmon. [ABSTRACT FROM AUTHOR]

In managed carnivore populations, natural mortality rate (d) is difficult to estimate directly, and context‐specific data are typically weakly informative about it. Nevertheless, natural mortality is potentially an important component of total mortality, particularly if additive to harvest or culling mortality. The natural mortality rate exhibits allometric or life‐history relationships that are invariant across diverse taxonomic groups, and it is valuable to derive estimates on this basis to serve as priors in later Bayesian models, steering parameter uncertainty towards biologically plausible values, and leading to more reliable model predictions and improved management recommendations. We used Bayesian hierarchical modeling and data from the literature to establish informative priors for instantaneous d as predictions scaled from body mass or maximum age. Posterior mean estimates of the scaling parameters of these models were −0.27 (body mass) and −1.07 (maximum age), respectively, conforming to expected values of −0.25 and −1.00. Direct estimates of d from published studies of coyotes (Canis latrans) in southern Texas, fisher (Pekania pennanti) in Sierra Nevada, and slender mongoose (Galerella sanguinea) in the Kalahari Desert were within the credible intervals of predictions for d using both models. We also compared survivorship curves based on model predictions with observed survivorship of red fox (Vulpes vulpes) from a variety of studies in Britain, among which intensity of culling varied markedly. Across all species, there was better support for the d prediction from maximum age, than from body mass. We thus recommend use of maximum age data to establish informative priors for d where possible. Posterior median predictions of d from maximum age were within 0.01–0.14/year of the direct estimates, whereas the differences between direct estimates and predictions from body mass were 0.04–0.27/year. Sensitivity analysis showed trivial effects of between‐sex differences in body mass, and age‐specific mortality, on predictions of d. Differences between body mass and maximum age model predictions were attributed to the relative importance of intrinsic and extrinsic mortality factors in the 2 approaches (i.e., maximum age predictions allowed for extrinsic factors to affect predicted mortality). © 2018 The Wildlife Society. Obtaining direct estimates of natural mortality rate of carnivores from tagging studies is expensive and impracticable, so we explored 2 different meta‐analytic methods for predicting natural mortality rate from data on either body mass or maximum age. Both methods produced valid predictions when compared to direct estimates, but we recommend using predictions from maximum age to establish Bayesian priors for use in future population dynamics modeling. [ABSTRACT FROM AUTHOR]

Thirty shards of medieval window glass from Elgin Cathedral in north‐east Scotland have been subjected to compositional analysis by portable X‐ray fluorescence and scanning electron microscopy – energy‐dispersive X‐ray spectroscopy. Comparison with previous analytical studies suggests that the majority of the glass was probably produced in France, while a smaller group may have been made in Germany. Significant differences in base glass composition were observed between colours. Two distinct blue glasses compositions were identified. The composition of the grisaille paint differs from paint on the continent, providing the first evidence that it was made using local Scottish lead and iron pigments. This work represents the largest analytical study of Scottish medieval window glass yet undertaken and presents insights into the transfer of medieval materials, technologies and trade routes. [ABSTRACT FROM AUTHOR]

One of the key challenges in recreational fisheries management is to provide a rational basis for decisions in the face of conflicting objectives, such as improving angling opportunities, maintaining satisfaction across a diverse fishing client base, controlling costs, and conserving wild populations. We developed a multi-criteria decision analysis approach for managing recreational trout fisheries (e.g., Rainbow Trout Oncorhynchus mykiss). The approach was implemented in a Bayesian decision network. The decision support tool, called “Stock-Optim,” provides a user-friendly interface for predicting fishery performance from alternate stocking prescriptions. The tool integrates survey information on angler typology and satisfaction with previously developed models for fish biology and fishery dynamics to more fully consider the biological and social outcomes of management decisions. Specifically, the tool evaluated alternative stocking options given three performance criteria: angler effort, angler satisfaction, and the cost of the stocking program. Predicted effort was highest for fish that were released in the size range of 8–20 g and at stocking densities of 200–500 fish/ha. Effort maximization at these rates and sizes is a result of compromise between the conflicting preferences of Rainbow Trout enthusiasts and occasional anglers toward fish size and harvest. Furthermore, lowering the stocking program’s costs will lead to lower stocking rates and thereby favor the enthusiasts. Currently, stocking levels in British Columbia are lower than levels that would maximize effort and are most consistent with a policy of maximizing satisfaction for Rainbow Trout enthusiasts and minimizing costs. Stock-Optim will allow managers to compare predicted outcomes from the current and alternative regimes with stated lake-specific or region-specific management objectives and regional averages and thereby more closely meet these objectives in the future. Lastly, the model was validated by comparing predicted effort with observed effort in stocked lakes. [ABSTRACT FROM AUTHOR]

Scottish window glass from both archaeological sites and historic buildings was examined using portable X-ray fluorescence (pXRF) and scanning electron microscopy - energy-dispersive X-ray micro-analysis (SEM-EDX). The elemental composition of the glass provides information regarding the materials used and, subsequently, an approximate range of dates of manufacture. pXRF is shown to be more vulnerable than SEM-EDX to the effects of surface corrosion and matrix effects in archaeological samples. The study showed that the production of window glass in Scotland from the 17th century onwards appears to closely parallel that in England. It also demonstrated the potential of pXRF for in situ studies of window glass in historic buildings. pXRF was used to assess two Scottish buildings; one in state care and one in private ownership. The building in state care, the Abbot's House at Arbroath Abbey, showed a uniform glass type, suggesting that the building was re-glazed completely at some point during the late 19th or early 20th century. The building in private ownership, Traquair House, had a range of glass types and ages, demonstrating a different maintenance and repair regime. This type of data can be useful in understanding historic buildings in the future, particularly if re-glazing is being considered. [ABSTRACT FROM AUTHOR]

Copyright of Conservation Biology is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The article presents a study regarding spatial surplus production modeling of Atlantic tunas and billfish. The study formulates and simulation-test a spatial surplus production model in order to accommodate nontarget species and minimize computational demand to enable simulation evaluation of spatial management strategies. It also investigates and discusses the implications of using spatially aggregated stock assessment for fisheries.

Fisheries scientists habitually consider uncertainty in parameter values, but often neglect uncertainty about model structure, an issue of increasing importance as ecosystem models are devised to support the move to an ecosystem approach to fisheries (EAF). This paper sets out pragmatic approaches with which to account for uncertainties in model structure and we review current ways of dealing with this issue in fisheries and other disciplines. All involve considering a set of alternative models representing different structural assumptions, but differ in how those models are used. The models can be asked to identify bounds on possible outcomes, find management actions that will perform adequately irrespective of the true model, find management actions that best achieve one or more objectives given weights assigned to each model, or formalize hypotheses for evaluation through experimentation. Data availability is likely to limit the use of approaches that involve weighting alternative models in an ecosystem setting, and the cost of experimentation is likely to limit its use. Practical implementation of an EAF should therefore be based on management approaches that acknowledge the uncertainty inherent in model predictions and are robust to it. Model results must be presented in ways that represent the risks and trade-offs associated with alternative actions and the degree of uncertainty in predictions. This presentation should not disguise the fact that, in many cases, estimates of model uncertainty may be based on subjective criteria. The problem of model uncertainty is far from unique to fisheries, and a dialogue among fisheries modellers and modellers from other scientific communities will therefore be helpful. [ABSTRACT FROM AUTHOR]

U.S. law requires that overfished fish populations be rebuilt within 10 years when biologically possible, and otherwise within the time it would take to rebuild in the absence of fishing plus one mean generation time (MGT). Most overfished populations can recover in less than 10 years; the exceptions are populations with very low productivity and some that are severely depleted. A range of harvest control policies, including constant fishing mortalities and variable harvest rate control rules, were compared in terms of their ability to rebuild overfished populations of five species within the required times. The North Atlantic swordfish Xiphias gladius and Gulf of Mexico red snapper Lutjanus campechanus populations were able to rebuild in 10 years, but the white marlin Tetrapturus albidus, sandbar shark Carcharhinus plumbeus, and darkblotched rockfish Sebastes crameri populations were not. The harvest policy that resulted in populations being rebuilt most rapidly was either a control rule that reduced fishing mortality with decreasing biomass or a constant harvest rate designed to meet the current rebuilding time requirement. The control rules we analyzed restricted catches at the beginning of the rebuilding period but allowed catches to increase rapidly as the population was rebuilt. Thus, there was a trade-off between relatively high catches early in the rebuilding period and high catches later in the rebuilding period when the population had been rebuilt and could sustain high catches. Whether the population was rebuilt more rapidly under a fixed rebuilding-time requirement or a control rule depended on the productivity of the population. [ABSTRACT FROM AUTHOR]

Recording a patient's vital signs is a basic requirement that in part informs clinical decision-making. Practice suggests that recording a trauma patient's temperature is occasionally overlooked in the emergency department. A staff survey was undertaken to gain an appreciation of knowledge and understanding of the issues that surround accidental or exposure hypothermia in trauma patients. Results demonstrate that nurses and doctors are unsure of how to define hypothermia and are not conversant with simple ways to prevent heat loss or rewarm patients. Complications from hypothermia such as coagulopathy and metabolic acidosis were seldom identified. Issues that limit staff recording temperature include patient access and acuity, lack of knowledge and confidence and access to temperature-measuring devices. These results emphasize the need for regular education. Implications for clinical practice were considered; an algorithm to guide staff on ways to improve the monitoring and management of temperature in trauma patients was developed. Opportunities for ongoing and further research were identified. [ABSTRACT FROM AUTHOR]

Despite growing concerns about overexploitation of sharks, lack of accurate, species-specific harvest data often hampers quantitative stock assessment. In such cases, trade studies can provide insights into exploitation unavailable from traditional monitoring. We applied Bayesian statistical methods to trade data in combination with genetic identification to estimate by species, the annual number of globally traded shark fins, the most commercially valuable product from a group of species often unrecorded in harvest statistics. Our results provide the first fishery-independent estimate of the scale of shark catches worldwide and indicate that shark biomass in the fin trade is three to four times higher than shark catch figures reported in the only global data base. Comparison of our estimates to approximated stock assessment reference points for one of the most commonly traded species, blue shark, suggests that current trade volumes in numbers of sharks are close to or possibly exceeding the maximum sustainable yield levels. [ABSTRACT FROM AUTHOR]

Copyright of Conservation Biology is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)