Evaluating Network Test Scenarios for Network Simulators Systems

Networks continue to grow as industries use both wired and wireless networks. Creating experiments to test those networks can be very expensive if conducted on production networks; therefore, the evaluation of networks and their performance is usually conducted using emulation. This growing reliance on simulation raises the risk of correctness and validation. Today, many network simulators have widely varying focuses and are employed in different fields of research. The trustworthiness of results produced from simulation models must be investigated. The goal of this work is first to compare and assess the performance of three prominent network simulators—NS-2, NS-3, and OMNet++—by considering the following qualitative characteristics: architectural design, correctness, performance, usability, features, and trends. Second, introduce the concept of mutation testing to design the appropriate network scenarios to be used for protocol evaluation. Many works still doubt if used scenarios can suit well to claim conclusions about protocol performance and effectiveness. A large-scale simulation model was implemented using ad hoc on-demand distance vector and destination-sequenced distance vector routing protocols to compare performance, correctness, and usability. This study addresses an interesting question about the validation process: “Are you building the right simulation model in the right environment?” In conclusion, network simulation alone cannot determine the correctness and usefulness of the implemented protocol. Software testing approaches should be considered to validate the quality of the network model and test scenarios being used

Data and initial model set-up for the 2022 VPA stock assessment of the eastern Atlantic and Mediterranean bluefin tuna

This document presents the data and initial model set-up for the 2022 Stock Assessment for the Eastern Atlantic and Mediterranean bluefin tuna stock. During the 2017 Data Preparatory meetings, several changes in the data used for previous assessments have been presented, among which the revision of the Task 1 and Task 2 statistics and the selection of the indices of abundance. This led to completely revisiting the catch at age matrix and the model specifications for the 2017 assessment. For the present document, the data over the historical period (1968-2015) were nearly identical, whereas the data for the years 2016-2020 and abundance indices were updated. As agreed in previous meetings, the initial model specifications were kept identical to the 2017 assessment as no change has been agreed on since then

Final data, explorations, model set-up and diagnostics for the 2022 VPA stock assessment of the eastern and Mediterranean Atlantic bluefin tuna stock

This document presents the modeling work done for the 2022 stock assessment for the Eastern and Mediterranean Bluefin tuna stock, during informal modeling subgroup meetings in June 2022. This document presents various runs built upon the base case for the 2017 stock assessment. These runs aim at addressing issues identified in the 2020 update assessment and aspects discussed during the informal meetings held in june 2022, regarding the inclusion of updated catch at age data, improvement of model stability in relation to Fratio estimates, the selection of the age for the plus group, inclusion of the WMED_GBYP_AER index. Following several explorations, the present work contains two runs that displayed improved diagnostics compared to previous runs. These models have improved retrospective patterns and no problematic issue was found through jittering the random number generator, jittering the starting values for the terminal F estimate, bootstrapping or through jackknife analysis

Seascape connectivity of European anchovy in the Central Mediterranean Sea revealed by weighted Lagrangian backtracking and bio-energetic modelling

Ecological connectivity is one of the most important processes that shape marine populations and ecosystems, determining their distribution, persistence, and productivity. Here we use the synergy of Lagrangian back-trajectories, otolith-derived ages of larvae, and satellite-based chlorophyll-a to identify spawning areas of European anchovy from ichthyoplanktonic data, collected in the Strait of Sicily (Central Mediterranean Sea), i.e., the crucial channel in between the European and African continents. We obtain new evidence of ecosystem connectivity between North Africa and recruitment regions off the southern European coasts. We assess this result by using bio-energetic modeling, which predicts species-specific responses to environmental changes by producing quantitative information on functional traits. Our work gives support to a collaborative and harmonized use of Geographical Sub-Areas, currently identified by the General Fisheries Commission for the Mediterranean. It also confirms the need to incorporate climate and environmental variability effects into future marine resources management plans, strategies, and directives

Atlantic Bluefin Tuna (Thunnus thynnus) Biometrics and Condition

The compiled data for this study represents the first Atlantic and Mediterranean-wide effort to pool all available biometric data for Atlantic bluefin tuna (Thunnus thynnus) with the collaboration of many countries and scientific groups. Biometric relationships were based on an extensive sampling (over 140,000 fish sampled), covering most of the fishing areas for this species in the North Atlantic Ocean and Mediterranean Sea. Sensitivity analyses were carried out to evaluate the representativeness of sampling and explore the most adequate procedure to fit the weight-length relationship (WLR). The selected model for the WLRs by stock included standardized data series (common measurement types) weighted by the inverse variability. There was little difference between annual stock-specific round weight-straight fork length relationships, with an overall difference of 6% in weight. The predicted weight by month was estimated as an additional component in the exponent of the weight-length function. The analyses of monthly variations of fish condition by stock, maturity state and geographic area reflect annual cycles of spawning and feeding behavior. We update and improve upon the biometric relationships for bluefin currently used by the International Commission for the Conservation of Atlantic Tunas, by incorporating substantially larger datasets than ever previously compiled, providing complete documentation of sources and employing robust statistical fitting.WLRs and other conversion factors estimated in this study differ from the ones used in previous bluefin stock assessments.Postprint4,411

Correction: Atlantic Bluefin Tuna (Thunnus thynnus) Biometrics and Condition

Correction: Atlantic Bluefin Tuna (Thunnus thynnus) Biometrics and ConditionPostprint4,411

Engraulis encrasicolus (Linnaeus, 1758)egg and larval distribution in the eastern coast of Tunisia in relation to environmental characteristics

An ichthyoplankton survey was conducted on the eastern coast of Tunisia from the 10th to 18th August 2004 with the investigation of 68 stations. The sampling period corresponded to stratified summer conditions, with average SST 26.97°C. The thermocline was found between 25 and 50 m depth. The eastern coast of Tunisia was influenced by the water exchanges between the eastern and western Mediterranean. Anchovy eggs and larvae were a major component of the ichthyoplankton, representing 26 and 19% of the total mean fish egg and larval abundances, respectively. Their mean abundances were 108 eggs.10 m-2 and 112 larvae.10 m-2. The spawning areas were mainly located off the 100 m isobaths, with the maximum abundance occurring near the shelf break, as opposed to the inshore waters where anchovy eggs and larvae were practically absent. Depth was the main factor controlling the distribution of anchovy eggs and larvae. Larval transport from the spawning areas is made evident following southward to south-eastward directionsPublicado

Distribution of tuna larvae in Tunisian east coasts and its environmental scenario

Early life stages of tuna species were investigated along the Tunisian east coast during the summer of 2008 by means of a larval survey conducted on board the R/V HANNIBAL. In this study we define the spawning grounds of tuna fishes in Tunisian waters and relate the tuna larvae spatial distribution to the hydrographic features and other environmental parameters. A total of 282 larvae of Atlantic bluefin tuna (Thunnus thynnus, Linnaeus, 1758), 902 of bullet tuna (Auxis rochei, Risso, 1810) and 19 of little tuna (Euthynnus alletteratus, Raf, 1810), were identified. High larval concentrations of bluefin tuna were located offshore (mean = 200 ± 18 m), at sea surface temperatures ranging between 23.7 to 25.3°C, whereas the highest concentrations of bullet and little tuna were located in shallower waters (mean = 135 ± 75 m), at sea surface temperature ranging between 25.1 to 25.9°C. According to their preference for waters with surface salinities ranging between 37.1 and 37.8, spawning of these species seems to occur mainly in mixed waters. Stations where tuna larvae were collected showed oxygen concentrations between 6.55 and 6.85 mg l-1, as well as low turbidity and chlorophyll a values, from 0.2 to 0.5 NTU a d less than 1 mg m-3, respectively. These three environmental factors were weakly correlated with tuna larvae abundancePublicado