The precision of international market sampling for North Sea herring and its influence on assessment

Market sampling is a key source of data for catch-at-age-based assessment. Little has been documented about the influence of potential error in these data on the precision of assessments and the management information they produce. This paper presents the results of a study of the precision of North Sea herring fish market sampling carried out by the UK, Denmark and the Netherlands. Data from eight years of market sampling were analysed to obtain the precision of estimated numbers-at-age in the catch. The market sample data was then used to estimate 1000 realisations of the international catch-at-age and mean weightsat- age in the catch. Three methods of estimating the variability of missing catch data were used and three options for the catch-at-age matrices were computed. These base datasets were utilised to obtain 1000 assessments conditional on the ICA (Integrated Catch-at-age Analysis) model. From the outcome of these assessments the influence of the market sampling programmes on the management of the stock are presented as 95␌onfidence intervals on the main management parameters (recruitment, SSB, F0-1 and F2-6). In addition, the influence of missing data is estimated. The implications of our conclusions on the requirements from a market sampling programme are discusse

The Use Of Recruitment Time-Series Structure And Environmental Information In Medium-Term Stock Projections

No abstracts are to be cited without prior reference to the author.Foremost amongst the competing aims for fisheries management is the maintenance of fish stocks for the forseeable future. To this end, it is imperative that managers are equipped with indicators of the expected level and variability of future population levels over the medium-term (typically, a five- to ten-year) time-scale, and that these indicators are sufficiently reliable, realistic and pertinent to the regulatory framework in which the managers operate. We extend the simulation approach currently employed within ICES stock assessment working groups by including characterisations of the time-series structure of residuals to fitted stock-recruitment models. The effect of the imposition of different hypothesised future environmental regimes is also investigated. North Sea cod (Gadus morhua L.) is presented as a germane and timely case study. We use the probability of the spawning stock biomass falling below the precautionary level of biomass, Bpa, as a diagnostic statistic to monitor projected performance. The relevance and utility of these new models for fisheries management is discussed, together with potential implications

A bioluminescent <i>Pseudomonas aeruginosa</i> wound model reveals increased mortality of type 1 diabetic mice to biofilm infection

Objective: To examine how bacterial biofilms, as contributing factors in the delayed closure of chronic wounds in patients with diabetes, affect the healing process. Method: We used daily microscopic imaging and the IVIS Spectrum in vivo imaging system to monitor biofilm infections of bioluminescent Pseudomonas aeruginosa and evaluate healing in non-diabetic and streptozotocin-induced diabetic mice. Results: Our studies determined that diabetes alone did not affect the rate of healing of full-depth murine back wounds compared with non-diabetic mice. The application of mature biofilms to the wounds significantly decreased the rate of healing compared with non-infected wounds for both non-diabetic as well as diabetic mice. Diabetic mice were also more severely affected by biofilms displaying elevated pus production, higher mortality rates and statistically significant increase in wound depth, granulation/fibrosis and biofilm presence. Introduction of a mutant Pseudomonas aeruginosa capable of producing high concentrations of cyclic di-GMP did not result in increased persistence in either diabetic or non-diabetic animals compared with the wild type strain. Conclusion: Understanding the interplay between diabetes and biofilms may lead to novel treatments and better clinical management of chronic wounds. </jats:sec

Simulation testing the robustness of stock assessment models to error: some results from the ICES strategic initiative on stock assessment methods

Abstract The World Conference on Stock Assessment Methods (July 2013) included a workshop on testing assessment methods through simulations. The exercise was made up of two steps applied to datasets from 14 representative fish stocks from around the world. Step 1 involved applying stock assessments to datasets with varying degrees of effort dedicated to optimizing fit. Step 2 was applied to a subset of the stocks and involved characteristics of given model fits being used to generate pseudo-data with error. These pseudo-data were then provided to assessment modellers and fits to the pseudo-data provided consistency checks within (self-tests) and among (cross-tests) assessment models. Although trends in biomass were often similar across models, the scaling of absolute biomass was not consistent across models. Similar types of models tended to perform similarly (e.g. age based or production models). Self-testing and cross-testing of models are a useful diagnostic approach, and suggested that estimates in the most recent years of time-series were the least robust. Results from the simulation exercise provide a basis for guidance on future large-scale simulation experiments and demonstrate the need for strategic investments in the evaluation and development of stock assessment methods.</jats:p