Comparison of Growth Parametres Between Sardine Sardina Pilchardus (Walbaum, 1792) and Anchovy Engraulis Encrasicolus (Linnaeus, 1758) from the Eastern Adriatic Sea

Sardine Sardina pilchardus (Walbaum, 1792) and anchovy Engraulis encrasicolus (Linnaeus, 1758), besides being ecologically very important pelagic resources, are also the most numerous fish species in Croatian fisheries landings. Hence, the aim of this study was to compare sardine and anchovy growth parameters: length, length-weight relationship, condition and age population structure. All samples (N=3313) were collected from purse seine catches of eastern Adriatic Sea, during period June 2015 – August 2016. Total lengths of sardine and anchovy ranged from 10.5 to 17.5 cm (average ± SD: 13.94 cm ± 1.07) and from 10.0 to 17.5 cm (average ± SD: 14.09 cm ± 0.88), respectively. Both sardine and anchovy length-weight relationship indicated positive allometry, although allometric coefficient was higher in anchovy (b=3.201) than in sardine (b=3.069). In general, condition of both species grew with fish length. Sardine and anchovy age composition varied from one to five years, while most of the analysed samples belonged to the 3 year class. Growth parameters were for anchovy: L∞=18.36cm; K=0.317; t0= -1.89 and for sardine L∞=19.71 cm; K=0.286; t0= -1.82.

Demographic potential of sex-age structure as a factor of population dynamics

The study aims to assess the sex-age population structure in terms of its impact on the up-coming dynamics of natural increase and, consequently, on the general change in the population size. There are various approaches to assessing this influence, proposed and used by scientists who have studied this aspect of demographic dynamics. This article discusses a relatively simple indica-tor of the sex-age population structure, which allows estimating its future influence on the ratio of births to deaths, and on the natural population growth. The indicator proposed is the so-called demographic potential of the sex-age structure, which is the ratio of female population aged 10–39 to the population of both sexes aged 65 years and older. The number of births in the next 10–15 years largely depends on the size of the first one, while the number of deaths in this period depends on the size of the second one.Before using the demographic potential of the sex-age structure to forecast the dynamics of natural population growth, a retrospective assessment of the relation of this potential with subse-quent natural population growth should be carried out for some particular time point in the past. We chose the sex-age structure of the mid-2000s and the natural increase (per 1000 population) in 2000–2015 for such assessment, accounting for 201 countries. The high value of the correlation coefficient (0.815) indicates that the current sex-age structure and its demographic potential can be used (with varying degrees of conditionality, of course) to forecast the future dynamics of natural growth. In turn, the size of the demographic potential of the sex-age structure of the population depends on the preceding levels of fertility and mortality.An assessment of the demographic potential of the sex-age population structure in mid-2015 for 201 countries of the world showed that in a number of countries in Asia and Africa the value of this potential exceeds 10, so significant natural population growth is highly probable there in the next 10–15 years. Meanwhile, in a number of European countries the value of this potential is less than 1 (i.e., the population aged 65 years and older is larger than the female population aged 10–39 years), which is likely to result in a very small natural increase (in case of a favorable mode of pop-ulation reproduction) or even a natural decline.

Kin competition, natal dispersal and the moulding of senescence by natural selection

Most theoretical models for the evolution of senescence have assumed a very large, well mixed population. Here, we investigate how limited dispersal and kin competition might influence the evolution of ageing by deriving indicators of the force of selection, similar to Hamilton (Hamilton 1966 J. Theor. Biol. 12 , 12–45). Our analytical model describes how the strength of selection on survival and fecundity changes with age in a patchy population, where adults are territorial and a fraction of juveniles disperse between territories. Both parent–offspring competition and sib competition then affect selection on age-specific life-history traits. Kin competition reduces the strength of selection on survival. Mutations increasing mortality in some age classes can even be favoured by selection, but only when fecundity deteriorates rapidly with age. Population structure arising from limited dispersal however selects for a broader distribution of reproduction over the lifetime, potentially slowing down reproductive senescence. The antagonistic effects of limited dispersal on age schedules of fecundity and mortality cast doubts on the generality of conditions allowing the evolution of ‘suicide genes’ that increase mortality rates without other direct pleiotropic effects. More generally, our model illustrates how limited dispersal and social interactions can indirectly produce patterns of antagonistic pleiotropy affecting vital rates at different ages.

Ostracods as Tsunami Tracers in Holocene Sequences

This review analyses the ostracod record in Holocene tsunami deposits, using an overview of the 2004 Indian Ocean tsunami impact on its recent populations and the associated tsunamigenic deposits, together with results from numerous investigations of other Holocene sequences. Different features such as the variability of the local assemblages, population density, species diversity, age population structure (e.g., percentages of adults and juvenile stages) or taphonomical signatures suggest that these microorganisms may be included amongst the most promising tracers of these high-energy events in marshes, lakes, lagoons or shallow marine areas.

POPULATION NATURAL DYNAMICS OF YUGOSLAV HILLMOUNTAIN AREAS - THE MIDDLE BOSNIA EXEMPLAR FOR THE PERIOD 1980-1989. YEAR

The middle Bosnia is a part of the central mountain area, Yugoslav integral large area complex. According to the administrativ-political organisation it is consisting of 37 municipalities with total are 12883 km/2 (ENCLOSURE 1). During ten years studied period the middle Bosnia population is characterized by the slow pulsating (variability 3,1 prom.) low values of middle type natality (the rates were between 15,2 prom. and 18,3 prom.). Furthermore, it is noticing the slow pulsating (variability 1,0 prom.) low mortality values with the rates between 6,3 prom. and 7,3 prom. (the rates of infantile mortality after Year 1984. were low and during first four studied years were between 25,5 prom. and 32,7 prom.). The results is the slow pulsating (variability 3,5 prom.) middle values of moderate natural population growth type (the rates were between 7,9 prom.) and 11,4 prom.). According to the indicated results, as wel as considering the characteristics of middle Bosnia sex and age population structure during studied period and Its social-economics development, and as per as the three-stages model of demographics transition, that is as per as the population development charac. teristics, it is possible to conclude that the studied population is very deep in a late transition substage.