Mathematical modeling of the demographic dividend (DD) capture applied in economy.

The purpose of this work is to develop tools and techniques for modeling the capture of the Demographic Dividend. We presented the ordinary differential equation (ODE) system modeling the variation of economically dependent and economically non dependent populations. The system uses natality, natural mortality, infant mortality, migration (incoming and outgoing), and transfers. The mathematical study of this ODE system shows the existence of an equilibrium point whose stability depends on a certain number of system parameters. Numerical simulations of the resulting model were performed using scenarios approach.

Mortality and exploitation rate of some reef fish in Ternate Island Waters

Fish population dynamics are determined by the balance between population increase resulted from growth and addition of new individuals (recruitment), and population decrease due to fishing mortality and natural mortality. It is important to understand fish resources condition, including their change pattern caused by pressures on coral reef fisheries resource in coastal area of Ternate Island. This research aimed to analyze mortality and exploitation rate of several reef fishes that caught at coastal area of Ternate Island. Stock assessment method was used to determine the mortality and exploitation rate of some reef fishes. Study results showed that the fishing mortality of the sample species was lower than their natural mortality, while the exploitation rate results also showed the same condition those found in mortality rate, where the fish with high growth coefficient tended to have high mortality rates.

A Review on Puerulus (Panulirus spp.) Resource Utilization in Indonesia Based on the Sense of Hearing: Auditory Receptor Organs

Highlight ResearchThe mortality of lobster seeds by predators in the first year is 96.0-99.4%It takes technology to catch seeds before being eaten by predatorsApplication of sound wave-based attractor technology to lobstersDo lobsters have the ability to hear sound waves?The lobster's sense of hearing begins to function from the puerulus stage AbstractIndonesia is a country that produces abundant lobster seeds (puerulus), however, there is a paradox, where natural mortality in the first year since entering the settlement phase can reach 96.0-99.4%. The use of lobster resources, especially in the puerulus stage, for cultivation, is very strategic. Therefore, it is necessary to improve puerulus fishing technology. In the capture fisheries sector, the use of the sense of hearing in fish resources has been carried out to increase catch productivity, by utilizing sound wave-based attractors’ technology. For lobster resources, to what extent is this technology applicable? Underwater sound waves are a phenomenon of compression and expansion of a medium as sound energy passes through it. This aspect of the study is still new and very prospective. The purpose of this review article is to answer some basic questions: Can lobsters be able to hear sounds that come from their surroundings, since when do lobsters sense of hearing begin to function, and anatomically what kind of auditory organs are in lobsters. The results of the review conclude as follows: lobsters have senses that are able to perceive or listen to sound waves (sound) from their surrounding environment, this ability has been possessed by lobsters since they were in the postlarva or puerulus stage. Anatomically, the organs that act as the sense of hearing in lobsters are: receptors on the body surface, chordotonal organs and statocyst organs.

The Use of a Length-Structured Multispecies Model Fitted Directly to Data in Near-Real Time as a Viable Tool for Advice

Fish communities are multispecies assemblages, so ideally multispecies models should be used directly for assessing this resource. However, progress in this direction has been slow, partly because these models are often more complex and take longer to fit, rendering them too slow to demonstrate near-real-time utility, and thus creating a perception that they are opaque to stakeholders. In this study we implemented a multispecies assessment for the Irish Sea, fitting a model of eight key stocks directly to catch and survey data. Two novel features of our approach allowed the multispecies model to be fitted within a few hours. Firstly, by using size-based theory and life-history invariants to specify many of the required properties of stocks, we reduced the number of general parameters that needed to be fitted directly to a more manageable 25. Secondly, by using state-of-the-art fitting methods, we found acceptable solutions quickly enough to provide assessments within the timescale of an advisory meeting. The outcomes were compared with the standard single species assessments of the same eight species. Model fits were generally good for either catch or at least one of the surveys, but not for all data sources at the same time, illustrating the challenges of fitting multiple stocks to different data sources simultaneously. Estimates of SSB and F agreed qualitatively with the assessments for most stocks with the exception of whiting. Estimates of natural mortality showed modest year to year variability, suggesting that single species assessments may be appropriate for short term tactical management. This method shows great promise for making multispecies assessments as a complement to existing assessments because of the rapid turnaround time and ability to respond at meetings to the requests of stakeholders. In addition, because these models avoid our current dependence on existing single species models they can be used to provide boundary conditions in natural mortality for standard assessment models and check for internal consistency in the assessment process. Furthermore, they are easily accessible because they are based upon freely available code.