987 resultados para Mass conservation
Resumo:
In this paper, the population biology of the velvet belly lanternshark Etmopterus spinax was studied and life-history coefficients determined. Age was estimated from sections of the second dorsal spine and validated by marginal increment analysis. Males attained a maximum age of 8 years while 11 year-old females were found. Several growth models were fitted and compared for both size-at-age and mass-at-age data, showing that even though this is a small-sized species, it has a relatively slow growth rate. This species matures late, specifically at 49.6 and 42.5% of the maximum observed ages for males and females, respectively. It has a low fecundity, with a mean ovarian fecundity of 9.94 oocytes and a mean uterine fecundity of 7.59 embryos per reproductive cycle. This species seems to have a long reproductive cycle, and even though no conclusive data were obtained, a 2-3 year cycle is possible. The estimated coefficients indicate that this species has a vulnerable life cycle, typical of deepwater squalid sharks. Given the high fishing pressures that it is suffering in the north-east Atlantic, this fish may already be facing severe declines or in risk of facing them in the near future. (C) 2008 The Authors Journal compilation (C) 2008 The Fisheries Society of the British Isles
Resumo:
Recreational shore fishing along 250 km of the south and south-west coast of Portugal was studied based on roving creel and aerial surveys. Surveys were conducted between August 2006 and July 2007, following a stratified random-sampling design and provided information on catch and effort, harvest and discards, angler demographics and fishing habits. Overall, 192 roving creel surveys, 24 aerial surveys and 1321 interviews were conducted. Based on the aerial surveys, a mean +/- s.e. total fishing effort of 705 236 +/- 32 765 angler h year(-1) was estimated, corresponding to 166 430 +/- 9792 fishing trips year(-1). Average time spent per fishing trip was 4.7 h. A total of 48 species, belonging to 22 families, were recorded in roving creel surveys. The most important species was Diplodus sargus, accounting for 44% of the total catches by number and 48% by mass. Estimated mean +/- s.e. total annual recreational shore fishing catch was 160.2 +/- 12.6 t year(-1) (788 049 +/- 54 079 fishes year(-1)), of which 147.4 +/- 11.9 t year(-1) (589 132 +/- 42 360 fishes year(-1)) was retained. Although overall shore-based recreational catches only corresponded to 0.8% of the commercial landings (only common species considered), D. sargus catches by recreational shore anglers were considerable, corresponding to 65% of the commercial landings. The implications of these results for integrated fisheries management and conservation are discussed, and future research proposed.
Resumo:
Two dimensional flow of a micropolar fluid in a porous channel is investigated. The flow is driven by suction or injection at the channel walls, and the micropolar model due to Eringen is used to describe the working fluid. An extension of Berman's similarity transform is used to reduce the governing equations to a set of non-linear coupled ordinary differential equations. The latter are solved for large mass transfer via a perturbation analysis where the inverse of the cross-flow Reynolds number is used as the perturbing parameter. Complementary numerical solutions for strong injection are also obtained using a quasilinearisation scheme, and good agreement is observed between the solutions obtained from the perturbation analysis and the computations.
Resumo:
This paper examines empirically the relative influence of the degree of endangerment of wildlife species and their stated likeability on individuals' allocation of funds for their conservation. To do this, it utilises data obtained from the IUCN Red List, and likeability and fund allocation data obtained from two serial surveys of a sample of the Australian public who were requested to assess 24 Australian wildlife species from three animal classes: mammals, birds and reptiles. Between the first and second survey, respondents were provided with extra information about the focal species. This information resulted in the dominance of endangerment as the major influence on the allocation of funding of respondents for the conservation of the focal wildlife species. Our results throw doubts on the proposition in the literature that the likeability of species is the dominant influence on willingness to pay for conservation of wildlife species. Furthermore, because the public's allocation of fund for conserving wildlife species seems to be more sensitive to information about the conservation status of species than to factors influencing their likeability, greater attention to providing accurate information about the former than the latter seems justified. Keywords: Conservation of wildlife species; Contingent valuation; Endangerment of species; Likeability of species; Willingness to pay
Resumo:
The thermal evolution process of RuO2–Ta2O5/Ti coatings with varying noble metal content has been investigated under in situ conditions by thermogravimetry combined with mass spectrometry. The gel-like films prepared from alcoholic solutions of the precursor salts (RuCl3·3H2O, TaCl5) onto titanium metal support were heated in an atmosphere containing 20% O2 and 80% Ar up to 600 °C. The evolution of the mixed oxide coatings was followed by the mass spectrometric ion intensity curves. The cracking of retained solvent and the combustion of organic surface species formed were also followed by the mass spectrometric curves. The formation of carbonyl- and carboxylate-type surface species connected to the noble metal was identified by Fourier transform infrared emission spectroscopy. These secondary processes–catalyzed by the noble metal–may play an important role in the development of surface morphology and electrochemical properties. The evolution of the two oxide phases does not take place independently, and the effect of the noble metal as a combustion catalyst was proved.
Resumo:
Recent data indicate that levels of overweight and obesity are increasing at an alarming rate throughout the world. At a population level (and commonly to assess individual health risk), the prevalence of overweight and obesity is calculated using cut-offs of the Body Mass Index (BMI) derived from height and weight. Similarly, the BMI is also used to classify individuals and to provide a notional indication of potential health risk. It is likely that epidemiologic surveys that are reliant on BMI as a measure of adiposity will overestimate the number of individuals in the overweight (and slightly obese) categories. This tendency to misclassify individuals may be more pronounced in athletic populations or groups in which the proportion of more active individuals is higher. This differential is most pronounced in sports where it is advantageous to have a high BMI (but not necessarily high fatness). To illustrate this point we calculated the BMIs of international professional rugby players from the four teams involved in the semi-finals of the 2003 Rugby Union World Cup. According to the World Health Organisation (WHO) cut-offs for BMI, approximately 65% of the players were classified as overweight and approximately 25% as obese. These findings demonstrate that a high BMI is commonplace (and a potentially desirable attribute for sport performance) in professional rugby players. An unanswered question is what proportion of the wider population, classified as overweight (or obese) according to the BMI, is misclassified according to both fatness and health risk? It is evident that being overweight should not be an obstacle to a physically active lifestyle. Similarly, a reliance on BMI alone may misclassify a number of individuals who might otherwise have been automatically considered fat and/or unfit.
Resumo:
Examines how society allocates support for species’ conservation when numbers involved are large and resources are limited. Rational behaviour suggests that species in urgent need of conservation will receive more support than those species that are common. However, we demonstrate that in the absence of balanced knowledge common species will receive support more than they would otherwise receive despite society placing high existence values on all species. Twenty four species, both common and endangered and some with a restricted distribution, are examined. We demonstrate that balanced information is vital in order to direct more support for species that are endangered than those that are not. Implications for conservation stemming from the findings are discussed.