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The precision of estimates of abundance based on data from fishery-independent surveys generally increases with sample size, assuming the availability of a species to sampling remains constant. In practice, the [...]

BACKGROUND: Angiolipomas are benign mesenchymal tumors comprising mature adipocytes and abnormal blood vessels, commonly found in the subcutaneous tissue of the trunk and rarely in the skull. Furthermore, sporadic cases of angiolipoma with arteriovenous fistula (AVF) have been reported. CASE DESCRIPTION: We reported the case of a 72-year-old woman who presented with head swelling, seizures, and cognitive dysfunction. Computed tomography and magnetic resonance imaging revealed a right frontal bone tumor exceeding a sagittal suture of up to 10.7 cm. Angiography revealed AVF and varices formation. Endovascular embolization was performed to treat the AVF and reduce blood loss during surgical resection. Two days after the embolization, a craniotomy was performed; however, uncontrollable bleeding was observed at the time of tumor resection. Postoperatively, the patient was symptom-free and has been stable for 2 years without recurrence. CONCLUSION: Despite careful preoperative evaluation and treatment planning, the patient in this case report was difficult to treat. Such cases require adequate preparation.

Population dynamics depend on trophic interactions that are affected by climate change. The rise in sea temperature is associated with the disappearance of sea ice in the Arctic. In the Arctic part of the Barents Sea, Atlantic cod, capelin and polar cod are three fish populations that interact and are confronted with climate-induced sea ice reductions. The first is a major predator in the system, while the last two are key species in Arctic and sub-Arctic ecosystems, respectively. There are still many unknowns regarding how predicted environmental change may influence the joint dynamics of these populations. Using time series from a 32 year long survey, we developed a state-space model that jointly modelled the dynamics of cod, capelin and polar cod. Using a hindcast scenario approach, we projected the effect of reduced sea ice on these populations. We show that the impact of sea ice reduction and concomitant sea temperature increase may lead to a decrease of polar cod abundance at the benefit of capelin but not of cod which may decrease, resulting in strong changes in the food web. Our analyses show that climate change in the Arcto-boreal system can generate different species assemblages and new trophic interactions, which is the knowledge needed for effective management measures. [ABSTRACT FROM AUTHOR]

Spatio-temporal models are essential tools for estimating abundance indices and quantifying the associated uncertainty. Time series of index uncertainties can be used to objectively determine the influence each index has on the assessment. This can involve reducing the influence of indices in years with limited data. However, incorporating uncertainty in age-length conversion into assessment models has remained a challenge. In this research, we propose an index estimation approach that combines an abundance-at-length model with a model for age-at-length to generate age-specific abundance indices. By jointly modeling abundance-at-length and age-at-length, we address uncertainties in both components of the index-at-age. Using North East Arctic haddock (Melanogrammus aeglefinus) as a case study, we validate the uncertainty of the indices by integrating them into the state space assessment model SAM. The results indicate that the uncertainty estimates are realistic, and we further demonstrate that incorporating uncertainty in age conversion has effects on the assessment results. Our case study demonstrates that incorporating the uncertainty in age-at-length data improves the characterization of uncertainty in stock assessment, and hence better accounts for risk in precautionary management. [ABSTRACT FROM AUTHOR]

Methods to reliably identify jump discontinuities in biological time series and to assess the specific contribution of various covariates are rapidly progressing. Here, we took advantage of these statistical improvements as well as those seen in complementary, down‐scaled climate and biogeochemical models to investigate causes of the substantial interannual variability observed in recruitment strength in hindcast analyses. This systematic meta‐analysis included 23 data‐rich, commercially valuable, warm‐ and cold‐temperate stocks in the North, Norwegian and Barents Seas. Since this study focuses on recruitment strength variability, we have used the term "recruitment regime shift" to distinguish from the concept of ecosystem regime shift. The breakpoint analysis revealed that the former criterion applied to more than half of the time series, mainly with respect to North Sea stocks but also to those in the Norwegian Sea. The exploratory analysis using vcGAM indicated that 1–3 shifts per stock were real, when using five drivers spanning spawning stock biomass to large‐scale climatic processes. Thus, non‐stationary relationships were extensively prevalent, indicating that each stock is uniquely adapted to its locally varying conditions. Outputs from the stationary GAM resembled those from the vcGAM but not after the threshold year. In‐depth case studies showed that the proxy of a given driver for the process which was to be included should be critically considered in a spatiotemporal context. Furthermore, the stock‐specific uncertainty associated with the given recruitment figures as such should also be an in‐built component of the model construct and thereby in the evaluation of the output. [ABSTRACT FROM AUTHOR]

A multispecies fishery management strategy evaluation (MSE) framework based on the example of the groundfish fishery in the Bering Sea and Aleutian Islands region of Alaska was used to examine the interplay between a bycatch species and three groundfish species. The study introduces a framework for a realistic multispecies fishery MSE by accounting for fleet dynamics, multispecies fishery quota allocation, and the temporal dynamics of technical interactions. The quota allocation and the fleet dynamics models were implemented using linear programming, and regression approaches were used to make a realistic projection of future users' behavioral response to changes in the fishery. The models were calibrated and then validated using historical and out-of-sample data, respectively. The results highlight the importance of accounting for technical interactions and their interannual dynamics for both quota allocation and fleet dynamics to design a realistic multispecies fishery MSE (without them, the amount of lost yield increased). Therefore, particular attention should be paid to understanding human behavior as well as its uncertainty and to refining approaches to incorporate this information into a multispecies fishery management strategy analysis. Un cadre devaluation de strategies de gestion (ESG) pour les peches multispecifiques reposant sur l'exemple de la peche aux poissons de fond dans la region de la mer de Behring et des Aleoutiennes de l'Alaska a ete utilise pour examiner l'interaction entre une espece de prise accessoire et trois especes de poissons de fond. L'etude presente un cadre pour une ESG realiste pour les peches multispecifiques qui tient compte de la dynamique de la flotte, de l'attribution des quotas de peche multispecifique et de la dynamique temporelle des interactions techniques. Les modeles d'attribution de quotas et de dynamique de la flotte ont ete mis en application en utilisant la programmation lineaire, et des approches de regression ont ete utilisees pour etablir des projections realistes de la reaction comportementale future des utilisateurs a des changements dans la peche. Les modeles ont ete etalonnes, puis valides en utilisant des donnees historiques et hors echantillon, respectivement. Les resultats soulignent l'importance de tenir compte des interactions techniques et de leur dynamique interannuelle tant pour l'attribution de quotas que la dynamique de la flotte, afin de concevoir une ESG realiste pour une peche multispecifique (sans quoi le rendement perdu augmente). Une attention particuliere doit donc etre accordee a la comprehension du comportement humain, ainsi que l'incertitude associee, et a l'amelioration des approches pour incorporer cette information dans l'analyse des strategies de gestion pour les peches multispecifiques. [Traduit par la Redaction], Introduction Multispecies fisheries are characterized by a complex combination of harvested animals, which vary in productivity and commercial importance. Some species may be productive and commercially valuable, while others are [...]

Estimating trends in abundance from fishery catch rates is one of the oldest endeavors in fisheries science. However, many jurisdictions do not analyze fishery catch rates due to concerns that these data confound changes in fishing behavior (adjustments in fishing location or gear operation) with trends in abundance. In response, we developed a spatial dynamic factor analysis (SDFA) model that decomposes covariation in multispecies catch rates into components representing spatial variation and fishing behavior. SDFA estimates spatiotemporal variation in fish density for multiple species and accounts for fisher behavior at large spatial scales (i.e., choice of fishing location) while controlling for fisher behavior at fine spatial scales (e.g., daily timing of fishing activity). We first use a multispecies simulation experiment to show that SDFA decreases bias in abundance indices relative to ignoring spatial adjustments and fishing tactics. We then present results for a case study involving petrale sole (Eopsetta jordani) in the California Current, for which SDFA estimates initially stable and then increasing abundance for the period 1986-2003, in accordance with fishery-independent survey and stock assessment estimates. L'estimation des tendances d'abondance a partir de taux de prises des peches est une des pratiques les plus anciennes des sciences halieutiques. De nombreux pays n'analysent cependant pas les taux de prises des peches parce que ces donnees pourraient ne pas distinguer les modifications des comportements de peche (ajustements du lieu de peche ou de l'utilisation d'engins) des tendances d'abondance. Nous avons donc developpe un modele d'analyse des facteurs de dynamique spatiale (SDFA) qui decompose la covariation des taux de prises multiespeces en differentes composantes representant la variation spatiale et le comportement de peche. La SDFA estime les variations spatiotemporelles de densite de poissons pour des especes multiples et tient compte du comportement de peche a de grandes echelles spatiales (c.-a-d., le choix du lieu de peche), tout en controlant pour le comportement des pecheurs a petites echelles spatiales (p. ex. l'heure du jour de l'activite de peche). Nous utilisons d'abord une experience de simulation multiespeces pour demontrer que la SDFA reduit le biais dans les indices d'abondance par rapport a la non-prise en compte des ajustements spatiaux et des tactiques de peche. Nous presentons ensuite les resultats pour une etude de cas portant sur la platija prtrale (Eopsetta jordani) dans le courant de Californie, pour laquelle la SDFA estime une abondance initialement stable, puis croissante pour la periode 1986-2002, ce qui concorde avec les estimations tirees devaluations independantes de la peche et devaluations des stocks. [Traduit par la Redaction], Introduction Many developed and developing countries collect detailed information from fishers regarding the location, timing, and catches from fishing operations. This fishing information is typically used to estimate total catch [...]

Selectivity in fish is often size-dependent, which results in differential fishing mortality rates across fish of the same age, an effect known as 'Lee's Phenomenon'. We extend previous work on using length composition to estimate the spawning potential ratio (SPR) for data-limited stocks by developing a computationally efficient length-structured per- recruit model that splits the population into a number of subcohorts, or growth-type-groups, to account for size- dependent fishing mortality rates. Two simple recursive equations, using the life history ratio of the natural mortality rate to the von Bertalanffy growth parameter (M/K), were developed to generate length composition data, reducing the complexity of the previous approach. Using simulated and empirical data, we demonstrate that ignoring Lee's Phenomenon results in overestimates of fishing mortality and negatively biased estimates of SPR. We also explored the behaviour of the model under various scenarios, including alternative life history strategies and the presence of size-dependent natural mortality. The model developed in this paper may be a useful tool to estimate the SPR for data- limited stock where it is not possible to apply more conventional methods. La selectivite des poissons depend souvent de la taille, ce qui se traduit par differents taux de mortalite par peche pour des poissons du meme age, un effet appele << phenomene de Lee >>. Nous elargissons des travaux anterieurs sur l'utilisation de la distribution des longueurs pour estimer le rapport du potentiel de reproduction (RPR) de stocks pour lesquels les donnees sont limitees, en developpant un modele par recrue structure par la longueur efficace sur le plan informatique qui divise la population en un certain nombre de sous-cohortes, ou groupes de type de croissance, pour tenir compte des taux de mortalite par peche dependant de la taille. Deux equations recursives simples, qui utilisent le rapport associe au cycle biologique du taux de mortalite naturelle et du parametre de croissance de von Bertalanffy (M/K), ont ete etablies pour generer des donnees de distribution des longueurs, reduisant du coup la complexite de l'approche anterieure. En utilisant des donnees simulees et empiriques, nous demontrons que le fait de ne pas tenir compte du phenomene de Lee entraine une surestimation de la mortalite par peche et des estimations du RPR caracterisees par des erreurs systematiques negatives. Nous avons egalement explore le comportement du modele pour differents scenarios, dont differentes strategies de cycle biologiques et la presence d'une mortalite naturelle dependant de la taille. Le modele pourrait constituer un outil utile pour estimer le rapport du RPR pour des stocks pour lesquels les donnees sont limitees auxquels l'application de methodes plus traditionnelles n'est pas possible. [Traduit par la Redaction], Introduction To maintain the long-term stability of yield from capture fisheries, the dynamics of fish populations and the impact of harvesting these populations must be understood. While there have been [...]

Many important ecological questions require accounting for spatial variation in demographic rates (e.g., survival) and population variables (e.g., abundance per unit area). However, ecologists have few spatial modelling approaches that (i) fit directly to spatially referenced data, (ii) represent population dynamics explicitly and mechanistically, and (iii) estimate parameters using rigorous statistical methods. We therefore demonstrate a new and computationally efficient approach to spatial modelling that uses random fields in place of the random variables typically used in spatially aggregated models. We adapt this approach to delay-difference dynamics to estimate the impact of fishing and natural mortality, recruitment, and individual growth on spatial population dynamics for a fish population. In particular, we develop this approach to estimate spatial variation in average production of juvenile fishes (termed recruitment), as well as annual variation in the spatial distribution of recruitment. We first use a simulation experiment to demonstrate that the spatial delay-difference model can, in some cases, explain over 50% of spatial variance in recruitment. We also apply the spatial delay-difference model to data for rex sole (Glyptocephalus zachirus) in the Gulf of Alaska and show that average recruitment (across all years) is greatest near Kodiak Island but that some years show greatest recruitment in Southeast Alaska or the western Gulf of Alaska. Using model developments and software advances presented here, we argue that future research can develop models to approximate adult movement, incorporate spatial covariates to explain annual variation in recruitment, and evaluate management procedures that use spatially explicit estimates of population abundance. De nombreuses questions ecologiques importantes necessitent la prise en consideration des variations spatiales de taux demographiques (p. ex. de survie) et de variables relatives a la population (p. ex. l'abondance par unite de surface). Les ecologistes disposent toutefois de peu d'approches de modelisation spatiale qui (i) peuvent etre calees directement sur des donnees referencees dans l'espace, (ii) representent de maniere explicite et mecaniste la dynamique des populations et (iii) emploient des methodes statistiques rigoureuses pour l'estimation de parametres. Nous presentons donc une nouvelle approche de modelisation spatiale efficace sur le plan computationnel qui fait appel a des champs aleatoires plutot qu'aux variables aleatoires normalement utilisees dans les modeles regroupes spatialement. Nous adaptons cette approche a la dynamique a differences retardees pour estimer l'incidence de la mortalite naturelle et par peche, du recrutement et de la croissance individuelle sur la dynamique spatiale d'une population de poissons. Nous developpons plus particulierement cette approche pour estimer les variations spatiales de la production moyenne de poissons juveniles (appelee le recrutement), ainsi que les variations annuelles de la repartition spatiale du recrutement. Nous utilisons d'abord une experience de simulation pour demontrer que le modele spatial a differences retardees peut, dans certains cas, expliquer plus de 50% de la variance spatiale du recrutement. Nous appliquons egalement le modele spatial a differences retardees a des donnees sur la plie royale (Glyptocephalus zachirus) dans le golfe d'Alaska et demontrons que le recrutement moyen (pour toutes les annees) est le plus grand pres de l'ile Kodiak, mais que, pour certaines annees, le recrutement maximum est observe dans le sud-est de l'Alaska ou dans l'ouest du golfe d'Alaska. A la lumiere des modeles et avancees logicielles presentes, nous arguons que des travaux futurs peuvent mener a des modeles permettant d'estimer approximativement les deplacements des adultes, d'integrer des covariables spatiales pour expliquer les variations annuelles du recrutement et d'evaluer les procedures de gestion qui font appel a des estimations spatialement explicites de l'abondance de la population. [Traduit par la Redaction], Introduction Ecologists are increasingly tasked with understanding how population and community dynamics vary spatially. Understanding spatial processes is necessary to predict many important phenomena, including the impact of global climate [...]

Fishery managers increasingly use marine closures as a tool to conserve ecosystems, biodiversity, and fish abundance. Despite the suggested benefits of closed areas, the limited or no data collection within them leads to difficulties assessing the population status. We investigated how spatial closures impacted the reliability of indices of abundance obtained from standardization methods applied to catch per unit effort data. The presence of closed areas generally introduced a bias in the derived index of abundance, and the magnitude of bias increased as the portion of the population in closed areas increased. In general, restricting the data to the areas that have been continuously fished over time performed best when spatial closures protected a small to medium portion of the population. However, as the portion of the population that was protected increased, the time series bias associated with this approach increased, and the use of an imputation approach was needed for adequate performance. Similarly, the collection of ancillary data in the closed area reduced bias in the estimate of final year depletion when area closures protected a large portion of the population. Les gestionnaires des peches font un usage croissant des zones marines fermees a la peche comme outil de conservation des ecosystemes, de la biodiversite et de l'abondance des poissons. Malgre les avantages presumes des zones fermees, la collecte limitee ou inexistante de donnees a l'interieur de ces zones fait en sorte qu'il est difficile d'evaluer l'etat des populations. Nous avons examine l'incidence des zones fermees sur la fiabilite des indices d'abondance obtenues par des methodes de normalisation appliquees a des donnees de captures par unite d'effort. La presence de zones fermees introduisait generalement un biais dans l'indice d'abondance calcule, et l'ampleur de ce biais augmentait a mesure qu'augmentait la proportion de la population dans les zones fermees. En general, le fait de ne considerer que des donnees provenant de zones ayant fait l'objet d'une exploitation continue dans le temps donnait les meilleurs resultats quand les zones fermees dans l'espace protegeaient une proportion faible ou moderee de la population. Toutefois, plus la proportion protegee de la population etait grande, plus le biais des series chronologiques associe a cette approche etait eleve, et l'utilisation d'une approche d'imputation etait necessaire pour obtenir des resultats adequats. De meme, la collecte de donnees accessoires dans la zone fermee reduisait le biais dans l'estimation de l'appauvrissement durant l'annee finale quand les zones fermees protegeaient une grande partie de la population. [Traduit par la Redaction], Introduction The analysis of commercial or recreational catch per unit effort (CPUE) data has a long history in fishery science because CPUE has often been the only data source available [...]