Multi-criteria dynamic decision under uncertainty: A stochastic viability analysis and an application to sustainable fishery management

Managing natural resources in a sustainable way is a hard task, due to uncertainties, dynamics and conflicting objectives (ecological, social, and economical). We propose a stochastic viability approach to address such problems. We consider a discrete-time control dynamical model with uncertainties, representing a bioeconomic system. The sustainability of this system is described by a set of constraints, defined in practice by indicators - namely, state, control and uncertainty functions - together with thresholds. This approach aims at identifying decision rules such that a set of constraints, representing various objectives, is respected with maximal probability. Under appropriate monotonicity properties of dynamics and constraints, having economic and biological content, we characterize an optimal feedback. The connection is made between this approach and the so-called Management Strategy Evaluation for fisheries. A numerical application to sustainable management of Bay of Biscay nephrops-hakes mixed fishery is given.     

Lipopolysaccharides of the motile aeromonads; core oligosaccharide analysis as an aid to taxonomic classification

Twelve motile Aeromonas strains have been examined with respect to the hexose and heptose monosaccharide residures present in the core region of their cell wall lipopolysaccharides. These strains were divided into three distinctly separate groups on the basis of the various combinations of hexose and heptose residues. The assignment of a strain to any one of the three groups furnishes a distribution which is substantially the same as that recently reported in a computerbased numerical analysis. All strains tested which were previoulsy named A. liquefaciens fall into the same group.     

A class of nonlinear productivity equations from fishery science and a new formulation

Owing to the lack of sufficient parameters, certain nonlinear exploitation models of common usage in fisheries management are thought to be too inflexible to portray the productivities of fish stocks with sufficient fidelity. These models [typified by the formulation of Schaefer, 1954] are statistically well behaved, however, since their governing equations all have fixed degrees of nonlinearity. Although one model of record [Pella and Tomlinson, 1969] offers an extra degree of parametric freedom not found in the aforementioned models, its productivity equation contains a variable exponent that introduces variable nonlinearity into the fitting procedure, which is an undesirable property that often leads to ill-determined parameter estimates. A new productivity formulation of fixed degree is developed here which exhibits the extra degree of parametric control not found in the Schaefer model but avoids the instabilities rising from variable exponents (as in the Pella-Tomlinson model) by having its parametric controls wholly contained by its coefficients. Some of the attributes and shortcomings of nonlinear single- and multiple-species models are also discussed.     

The chloride-water balance sheet; an aid in the management of difficult fluid balance problems

In cases in which there is massive loss of fluids or electrolytes or prolonged decreased urinary output, an absolutely accurate knowledge of all water and chloride intake and output by all routes is necessary to avert large and often fatal errors in water and electrolyte therapy based on estimates made from nurses' notes alone. By use of the Scribner water-chloride balance sheet method of recording data, it is possible to determine with the necessary accuracy how much fluid and what kind of electrolytes to administer to achieve and maintain balance. The method is simple and can be put into effect in any hospital with the cooperation of an educated nursing and laboratory staff.     

Ecology and fishery management of reservoirs in India

India has 19 370 small reservoirs with a total water surface area of 3 153 366 ha. At least 100 of them have been subjected to scientific studies. Habitat variables responsible for a reservoir's productivity can be summed up into climatic, morphometric and hydro-edaphic factors. The peninsular reservoirs are characterized by a narrow range of fluctuations in water and air temperature across seasons, a phenomenon which prevents the formation of thermal stratification. Many reservoirs in the upper peninsula show thermal stratification during summer. Wind-induced turbulence facilitates the return of nutrients to the trophogenic zone. Most reservoirs on the mountain slopes of Western Ghats, Himalayas and the other highlands are deeper, with steeper basin walls, compared to irrigation impoundments. Mean depth does not show any direct correlation with productivity, either at primary or fish level. A high shoreline development index gives a better indication of productivity. Plankton, benthos and periphyton pulses of Indian reservoirs coincide with the months of least level fluctuations. Oligotrophic tendencies shown by some reservoirs are mainly due to poor nutrient status and other chemical deficiencies. In most cases, poor water quality is accountable to poor catchment soil. Low levels of phosphate and nitrate are not indicative of low productivity due to quick recycling of these nutrients. Specific conductivity reflects the production propensities of reservoirs satisfactorily. Almost all productive reservoirs have a klinograde oxygen curve and a vertical stratification of chemical variables such as pH, carbon dioxide, total alkalinity and specific conductivity. High seasonal rainfall and discharge of water during monsoon result in high flushing rates, which do not favour colonization by macrophytic communities. Similarly, inadequate availability of suitable substrata retards the growth of periphyton. Plankton constitutes the major link in the trophic structure. A rich plankton community with well-marked succession is the hallmark of Indian reservoirs with blue-green algae as the major component. The main factors that retard the growth of benthos are a rocky bottom, frequent water level fluctuation and rapid deposition of silt and other suspended particles. Large reservoirs, on average, harbour 60 species of fishes, of which at least 40 contribute to the commercial fisheries. Fast-growing Indian major carps are the prominent commercial fishes. Dam construction has adversely affected populations of many other species such as Tenualosa ilisha, Torspp. and Cirrhinus spp. Formulae for estimating fish yield potential and stocking density are described. While culture-based fisheries have been successfully practiced in many small reservoirs, the management norm followed in medium and large reservoirs is primarily on capture fishery. In large and medium reservoirs, stocking was successful only when stocked fishes bred. Indian experience on species enhancement and introductions is described. Environmental enhancement of small reservoirs has been attempted in some reservoirs of Tamil Nadu. Modeling, using standard population parameters, such as the density-dependent growth, size dependent mortalityand weight–length relationshipis discussed. Two exotic fishes viz., Oreochromis mossambicus and Cyprinus carpio have been introduced into Indian reservoir with discouraging results. Hypophthalmichthys molitrix, after an accidental introduction, has performed well in Gobindsagar, a reservoir with a distinct cold water regime. Reservoir fisheries in India are well poised for development, provided scientific management norms are adopted.     

Fossil record of cladoceran and algal responses to fishery management practices

1. We hypothesized that the fishery management practices of toxaphene application and trout stocking would affect non-target organisms in lakes. Because these practices were rarely monitored in the past, cladoceran and algal assemblages were quantified in sediment cores from two lakes treated 30+ years ago to determine the long-term response of organisms near the base of the food chain. 2. Chydorids were remarkably resistant over the short term (a few years) in both the oligotrophic and eutrophic lakes despite toxaphene treatments that extirpated native fish and other invertebrates. In the oligotrophic lake (Annette Lake), six chydorid taxa were less abundant in the years following treatment, although no loss of species richness was detected. In the eutrophic lake (Chatwin Lake), the dominant Chydorus cf. sphaericus declined coincident with toxaphene treatment, but longer-term declines of all taxa were probably related to food web or other changes rather than to toxaphene toxicity. Cause and effect coupling was complicated by the fact that many chydorids were present at low concentrations in some pretreatment samples. 3. The algal communities (as fossil pigments) responded to treatment differently in the two lakes. In the oligotrophic lake, planktonic diatoms, dinoflagellates and chlorophytes were replaced as dominants by deep-water or benthic blooming cryptophytes, chrysophytes and cyanobacteria. This shift occurred along with increases in large daphnids and the ‘grazing indicator’, pheophorbide a. While both lakes appear to have had enhanced pigment preservation following treatment, the eutrophic lake encountered few long-term changes in its fossil pigment assemblage. Redundancy analysis estimated that the presence or absence of stocked trout explained much of the variation in the algal assemblages, particularly in the oligotrophic lake. 4. Toxaphene remained elevated in profundal sediments from these lakes 30 and 35 years after treatment.     

A new approach to the species classification problem in floristic analysis

A new method of species (inverse) classification of vegetation data, i.e. classification of species into groups with similar ecological tolerances, is presented which overcomes the problems of species abundance distorting the results. The algorithm TWO-STEP is based on the use of an asymmetric measure of dissimilarity: where i, j are species, h is the stand, n is the total number of stands, and x_ih is the amount of species i in stand h. The algorithm uses the rows of the asymmetric dissimilarity matrix generated as above to form a second symmetric dissimilarity matrix using the measure: where m is the number of species and k the species. Flexible sorting is applied to generate a species classification. Comparison of results after applying the TWO-STEP algorithm and a standard alternative to an artificial data set demonstrates its efficacy. TWO-STEP also shows considerable advantages over previous analyses for a Queensland rainforest data set (quantitative) and an English heath (qualitative) data set. Normalization of species data appears advantageous for quantitative data only.     

海洋渔业资源地理信息系统应用的时空问题

利用GIS描述海洋渔业资源时空动态变化。建立渔业资源评估模型和预测模型,是当前渔业现代化的重要趋势之一．在回顾海洋渔业地理信息系统(MFGIS)发展的基础上。分析了其应用实例及不足,重点探讨了MFGIS所面临的时空数据获取与标准、时空数据表达、时空动态尺度和时空统计与分析模型四方面的技术内涵。并讨论了解决途径．     

Numeric classification as an aid to spectral mapping of vegetation communities

This study demonstrates a vegetation mapping methodology that relates the reflectance information contained in multispectral imagery to traditionally accepted ecological classifications. Key elements of the approach used are (a) the use of cover rather than density or presence/absence to quantify the vegetation, (b) the inclusion of physical components as well as vegetation cover to describe and classify field sites, (c) development of an objective land cover classification from this quantitative data, (d) use of the field sample sites as training areas for the spectral classification, and (e) the use of a discriminant function to effectively tie the two classifications together. Land cover over 39000 ha of Australian chenopod shrubland was classified into nine groups using agglomerative hierarchical clustering, a discriminant function developed to relate cover and spectral classes, and the vegetation mapped using a maximum likelihood classification of multi-date Landsat TM imagery. The accuracy of the mapping was assessed with an independent set of field samples and by comparison with a map of land systems previously interpreted from aerial photography. Overall agreement between the digital classification and the land system map was good. The units that have been mapped are those derived from numeric vegetation classification, demonstrating that accepted ecological methods and sound image analysis can be successfully combined.     

The importance in fishery management of leaving the big ones

Research by Berkeley et al. and by Bobko and Berkeley has recently demonstrated that older individuals of some fish species produce larvae that have substantially better survival potential than do larvae from younger fishes. These new findings augment established knowledge that larger individuals usually have exponentially greater fecundity. This is important because commercial fisheries and especially recreational fishing often target the larger fish. The protection of larger or older individuals is necessary for the sustainability of species currently exploited by humans.     

The presence of quinones in the genus Cyperus as an aid to classification

The absence or presence and type of quinonoid constituents in the roots and rhizomes of the genus Cyperus have proved consistent with the accepted divisions within this genus but not with the arrangement within these divisions.     

Progesterone transformation as a biochemical aid in classification of the genusEmericella

A total of 65 isolates representing 13Emericella taxa (5 isolates of each of 12 species and 1 variety) had the ability to transform progesterone into 11α-hydroxyprogesterone. A systematic variation could be observed between the different testedEmericella taxa with respect to the transformation products. The isolates were divided according to the transformation types into six groups: (1) progesterone was hydroxylated into 6β-hydroxyprogesterone, 11α-hydroxyprogesterone and 6β, 11α-dihydroxyprogesterone— found inEmericella acristata andE. dentata; (2) E. aurantio-brunna andE. parvathecia hydroxylated progesterone into 11α-hydroxyprogesterone, 17α-hydroxyprogesterone and 11α,17α-dihydroxyprogesterone; (3)E. nidulans andE. quadrilineata formed the same three products as members of group (2) and form epicortisol; (4)E. nidulans var.lata, E. bicolor andE. variecolor transformed progesterone into a mixture of mono- di-and trihydroxy products; (5)E. striata andE. sublata exhibited an oxidative splitting of the progesterone side chain in position C-17 and hydroxylated progesterone into mono-and dihydroxy products; (6)E. rugulosa andE. unguis had the ability to degrade progesterone side-chain and to hydroxylate it into mono-, di- and trihydroxy products. This biochemical differentiation may supplement the morphological and other biochemical criteria used in the classification of theEmericella taxa.     

A study to determine the underlying reason for abnormal glandular cytology and the formulation of a management protocol

A retrospective review is presented of 89 patients with glandular dyskaryosis in order to formulate a management protocol. Fifteen patients had cervical intraepithelial neoplasia (CIN) without glandular abnormality (17%). One patient had adenocarcinoma in situ of the cervix and one patient had vaginal intraepithelial neoplasia (VAIN) grade III. Twenty‐two patients had endometrial carcinoma (24.5%) and 11 patients had cervical carcinoma (12.5%). Of the patients presenting with post‐menopausal bleeding as well as having glandular dyskaryosis, 69% had a gynaecological malignancy. In conclusion, colposcopy and out‐patient endometrial sampling are recommended in all cases. Patients with abnormal endometrial sampling require hysteroscopy. Cone biopsy is necessary to exclude occult glandular disease if cytology remains abnormal despite negative colposcopy and sampling.     

Predictive modelling to aid the regional-scale management of a vertebrate pest

Extensive resources are allocated to managing vertebrate pests, yet spatial understanding of pest threats, and how they respond to management, is limited at the regional scale where much decision-making is undertaken. We provide regional-scale spatial models and management guidance for European rabbits (Oryctolagus cuniculus) in a 260,791 km² region in Australia by determining habitat suitability, habitat susceptibility and the effects of the primary rabbit management options (barrier fence, shooting and baiting and warren ripping) or changing predation or disease control levels. A participatory modelling approach was used to develop a Bayesian network which captured the main drivers of suitability and spread, which in turn was linked spatially to develop high resolution risk maps. Policy-makers, rabbit managers and technical experts were responsible for defining the questions the model needed to address, and for subsequently developing and parameterising the model. Habitat suitability was determined by conditions required for warren-building and by above-ground requirements, such as food and harbour, and habitat susceptibility by the distance from current distributions, habitat suitability, and the costs of traversing habitats of different quality. At least one-third of the region had a high probability of being highly suitable (support high rabbit densities), with the model supported by validation. Habitat susceptibility was largely restricted by the current known rabbit distribution. Warren ripping was the most effective control option as warrens were considered essential for rabbit persistence. The anticipated increase in disease resistance was predicted to increase the probability of moderately suitable habitat becoming highly suitable, but not increase the at-risk area. We demonstrate that it is possible to build spatial models to guide regional-level management of vertebrate pests which use the best available knowledge and capture fine spatial-scale processes.