Water Stocks Research Articles

Population size and yield of Baffin Bay beluga (<i>Delphinapterus leucas</i>) stocks

A surplus production model within a Sampling, Importance Resampling (SIR) Bayesian analysis was used to estimate stock sizes and yields of Baffin Bay belugas. The catch of belugas in West Greenland increased in 1968 and has remained well above sustainable rates. SIR analysis indicated a decline of about 50% between 1981 and 1994, with a credibility interval that included a previous estimate of 62%. The estimated stock sizes of belugas wintering off West Greenland in 1998 and 1999 were approximately 5,100 and 4,100 respectively and were not significantly different than an estimate based on aerial surveys combined for both years. Projected to 1999 this stock can sustain median landings of 109 whales with a total kill of about 155, based on posterior estimates of struck and lost plus under-reporting. The declining stock size index series did not provide sufficient information to estimate the potential maximum rate of population growth, the number of whales struck and lost, or the shape of the production curve with precision. Estimating these parameters requires an index time series with a marked step change in catch or a series with increasing stock sizes. The stock size estimate for the belugas wintering in the North Water in 1999 was approximately 14,800 but there is no information about the population biology of these whales. The estimated maximum sustainable yield (landed) for the North Water stock was 317 belugas.

Activation of the growth hormone/insulin-like growth factor axis by treatment with 17α-methyltestosterone and seawater rearing in the tilapia, Oreochromis mossambicus

Effects of 17α-methyltestosterone (MT) treatment and environmental salinity on the growth hormone (GH)/insulin-like growth factor (IGF) axis were examined in the euryhaline tilapia, Oreochromis mossambicus. Yolk-sac fry were collected from brood stock in fresh water (FW). After yolk-sac absorption, they were assigned randomly to 1 of 4 groups: FW, MT treatment in FW, SW, and MT treatment in seawater (SW). After 147 days, FW controls had the lowest levels of GH mRNA followed by FW fish treated with MT and SW control fish. Seawater fish fed with a diet containing MT, which grew the fastest, had significantly higher levels of GH mRNA than all the other groups. A significant correlation was observed between GH mRNA and the size of the individual fish. By contrast, plasma GH levels did not vary significantly among the groups. Pituitary GH mRNA levels, plasma IGF-I levels, and fish size varied in a correlated pattern, i.e., SW+ MT> FW+ MT= SW control > FW control. The tilapia pituitary produces two prolactins (PRLs), PRL 177 and PRL 188. Prolactin 177, but not PRL 188, exhibits growth-promoting actions in FW tilapia. Pituitary mRNA levels of both PRLs were significantly higher in fish reared in FW than those reared in SW. Treatment with MT significantly increased mRNA levels of both PRLs in FW, but had no effect on SW fish. No correlation was seen between plasma PRL levels and growth or between PRL mRNA levels and growth. These results indicate that SW rearing and MT treatment stimulate the GH/IGF-I axis, and suggest that pituitary GH mRNA at this stage of development is a better indicator of growth than plasma levels of GH and IGF-I.

Technical Responses to Challenges in Milkfish Aquaculture

Milkfish (Chanos chanos) has been cultured in Asia for centuries. In 1999 the total world production of cultured milkfish was estimated at 381,930 metric tons. To meet the production target with less available land for farming, traditional culture in shallow-water ponds, which relied on wild-caught fry from coastal waters and on benthic algae as the main food, had to be modified. To increase unit production, a deep-water pond culture system was developed in the mid-1970s. As a result of the increased water depth and stocking density, in addition to the use of formulated feed and aeration devices, unit production underwent a 5- to 8-fold increase. In the Philippines, pen and sea cage culture methods were developed to increase production. The life cycle of milkfish was completed in captivity before technology for mass production in the hatchery was established in the late 1980s. Preventing overproduction of milkfish is currently an important issue in milkfish producing countries. IThe improvement in processing technology, the diversification of products, and the establishment of international marketing networks are important challenges to the industry. The extension of milkfish aquaculture technology to other countries is a goal that may greatly benefit mankind.

Levels and patterns of persistent organochlorines in minke whale ( Balaenoptera acutorostrata) stocks from the North Atlantic and European Arctic

Regional variation in PCBs and organochlorine (OC) pesticide concentrations was examined using the blubber of 155 minke whales ( Balaenoptera acutorostrata) sampled in seven regions in the North Atlantic and European Arctic, including western and southeastern Greenland, the Norwegian Sea, the North Sea and the Barents Sea. The levels and relative proportions of OCs were also used to examine the boundaries for North Atlantic minke whale stocks previously defined by the International Whaling Commission (IWC). Concentrations of major OC groups (ΣPCB, 89.1–22 800 ng/g lipid; ΣDDT, 65.3–6280 ng/g lipid; ΣCHL, 33.3–2110 ng/g lipid) generally increased from west to east, while HCH concentrations (ΣHCH, <1–497 ng/g lipid) showed the opposite trend. Statistical comparison between six regions using sex-adjusted least squared mean concentrations showed that minke whales from the Barents Sea had significantly higher concentrations of ΣPCBs than those from the Vestfjorden/Lofoten, the North Sea, and west Svalbard, as well as significantly higher ΣDDT concentrations compared to west Greenland animals. The differences in concentrations suggest that west and southeast Greenland minkes may represent one group of whales, which are distinct from both the Jan Mayen minkes and those from other IWC defined stocks in northern European waters. Principal components analysis using proportions of 71 PCB congeners and 20 OC pesticides (of total OCs) did not reveal any major differences among groups although minkes from the North Sea were distinguished from those from Greenland waters by higher loadings of more highly chlorinated PCBs and recalcitrant OC pesticides. The general similarity in mean levels of ΣPCBs, ΣDDT and ΣCHL, as well as mean principal components analysis scores, among minkes sampled at Jan Mayen, Svalbard, Vestfjorden/Lofoten, the North Sea and the Barents Sea suggests that the whales are quite mobile and may feed in multiple areas within the northeastern Atlantic.

Empirical modelling of interannual trends in abundance of squid ( Loligoforbesi) in Scottish waters

This study compares alternative empirical models for forecasting interannual variation in squid ( Loligo spp.) abundance around Scotland (UK). Annual abundance indices (1970–1996) were derived from fishery data, for stocks in coastal waters (northern North Sea and West Coast) and the Rockall area. Abundance in coastal waters was correlated with several annual environmental indices, including the winter North Atlantic Oscillation index and the average sea surface temperature (SST) and sea surface salinity (SSS) in the northern North Sea. Regression models, relating fishery abundance to annual environmental indices, and time-series models, predicting abundance from the previous year’s abundance, could both provide reasonable fits to observed abundance data. Model fits obtained for coastal waters were generally better than those for the Rockall area. Regression models produced consistently poor forecasts whereas time-series models produced satisfactory forecasts for the years 1997–1999. Forecast accuracy for the time-series models could be improved by taking into account environmental variables. Thus, adding effects of SST in May in the northern North Sea in the current and previous years improved a time-series model of squid abundance in coastal waters. Improved forecasts were also achieved by fitting time-series models to monthly abundance data. The apparent influence of May SST in the northern North Sea on the coastal fishery could indicate that SST affects recruitment strength. Results for the offshore Rockall fishery suggest that large-scale and longer-term oceanographic processes may be involved.

ウェットエンドプロセスの新しい波Ｗｅｔ Ｅｎｄ Ｐｒｏｃｅｓｓテクノロジー

The future generation of paper machines will be characterized by increased operating speeds and at the same time higher product quality demands, including machine directional (MD) and cross machine directional (CD) profile stability. To meet these new requirements, the wet end process (WEPTM) around the wet end of the paper machine needs to be redesigned. New machines and tools are presented here for mixing the stock and filler components, for white water dilution, stock cleaning and deaeration ion, adding of retention agents and for the entire white water handling. The overall goal is to optimize the entire WERETM for more profitable operation.

Desecuritizing the Water Issue in Singapore—Malaysia Relations

********** A number of scholars have argued that water may be a determining factor sparking armed conflict between Singapore and Malaysia. They highlight Singapore's dependence on Malaysia for half of its water needs (a supply guaranteed by two compacts signed in 1961 and 1962), and speculate that Malaysia prematurely abrogates the agreements, water-stressed Singapore will have no qualms about invading its neighbour to secure access to the water stocks. This article examines Singapore's water situation and argues that the prevailing scholarship is too alarmist. It maintains that Singapore has the means to achieve a measure of water self-sufficiency and is not vulnerable to Malaysia's use of the water link as leverage. Consequently, scholars should begin to regard the water issue between Singapore and Malaysia as desecuritized. Introduction Within the past decade, a burgeoning studies literature coalescing around the phrase security has emerged. The deluge of articles and books calling for the redefinition of beyond the confines of military threats to include the environment has generated a lively debate within academia. (1) Within this broad environmental school, two distinctive standpoints on the scope of the scholars' or policy-makers' concerns have emerged. One has tended to view the environment as a dependent variable for analysis, such that thus takes on the meaning of of the environment. (2) The other posits the environment as an independent variable and is interested in the conflict dimension of interstate relations as they crop up in political, economic, diplomatic, or military confrontations stemming from environmental antagonism, be it local, regional, or global in nature. (3) Security studies of the latter genre argue that resource scarcity or one state's forcible deprivation of a resource from another plays an important contributory role in inducing wars. Analysts taking the latter approach and studying the linkage between nation-states, water security, and conflict, in particular, have generated insightful hypotheses about the respective independent! dependent variable relationship between a renewable resource like fresh water and war. They argue that, assuming water is fundamental to a country's survivability, sovereignty, economic development, and, social and political stability, any attempt to curtail that state's access to the resource may trigger violent retaliation. (4) As Peter Gleick contends, if water provides [a state with] a source of economic or political strength... ensuring access to water provides a justification for going to war, and water-supply systems can become a goal of military conquest. (5) Informed by fresh theoretical perspectives, a number of case studies focusing on the links between water scarcity or deprivation and interstate conflict have appeared. Indeed, scholars advancing the water agenda have added an important dimension to scholarly understanding of how access to water resources may influence geopolitical events in the water-stressed Middle East, or the humid Mekong region in tropical Southeast Asia. (6) The clarion call for more attention to be given to a state's water could not have been timelier for those concerned about the situation in Singapore. In recent years, a number of scholars examining bilateral tensions among member states of the Association of Southeast Asian Nations (ASEAN) have suggested that water may be a determinant factor sparking violent conflict between Singapore and Malaysia. (7) The central assumption behind that assertion is that Singapore is bereft of sufficient domestic water reserves and is highly reliant on Malaysia for at least half of its water supply, a provision guaranteed by two compacts signed in 1961 and 1962 and expiring respectively in 2011 and 2061. (8) Although Singapore separated from Malaysia in August 1965 under acrimonious circumstances, the water links continued. …

An Economic Drought Management Index to Evaluate Water Institutions' Performance Under Uncertainty and Climate Change

This paper proposes a new Economic Drought Management Index (EDMI) that could assist water managers to inter-temporally manage water reservoirs. The index's main appeal is that it can be easily interpreted and that it encompasses in a single number hydrological processes, structural constraints, water institutions' rules and the economic benefits of the customers served by the supply system. An empirical application of EDMIs is performed for two irrigation districts in Andalusia (Southern Spain), that are managed under different institutional arrangements. EDMIs are then re-evaluated and estimated for various scenarios of climate change, and for a 8-year real period, which includes three consecutive drought years. Results show that the region's vulnerability to drought could be reduced following the interpretation of the EDMIs. EDMIs under climate change scenarios suggest that the water stocks management criteria should be vastly reformed. Lastly, EDMIs evaluated for the actual period of 1990-98 indicated that the severe drought suffered by the region could have been partially avoided, or at least delayed, if water managers had followed the recommendations that are warranted by the EDMIs evaluated for those years.

Optimal cropping patterns under water deficits

A mathematical programming model is proposed for optimal cropping patterns under water deficits in dry regions. Crops may be deliberately under-irrigated in order to increase the total irrigated area and possibly the profit. An operating policy will identify both the total area and the irrigation level allocated to a given selected crop taking into account the possible successors and predecessors of this crop. Both annual and seasonal crops are examined in the same study. The model starts by identifying the optimal operating policy for each grower in the region having a given stock of irrigation water. Then, in order to allocate water efficiently among growers, the model determines the global optimal cropping plan of the entire region. To solve efficiently the problem, a decomposition algorithm is developed. Also some useful economic interpretations are given.

R&amp;D policies for desalination technologies

In many arid and semi-arid regions whether or not to desalinate seawater has long been a non-issue and policy debates are focused on the timing and extent of the desalination activities. We analyze how water scarcity and demand structure, on the one hand, and cost reduction via R&D programs, on the other hand, affect the desirable development of desalination technologies and the time profiles of fresh and desalinated water supplies. We show that the optimal R&D policy is of a non-standard most rapid approach path (NSMRAP) type, under which the state of desalination technology — the accumulated learning from R&D efforts — should approach a pre-specified target process as rapidly as possible and proceed along it thereafter. The NSMRAP property enables a complete characterization of the optimal water policy. The renewable nature of the fresh water stock permits a non-monotonic behavior of the optimal stock process: under certain conditions, the stock is depleted, to be fully or partly) refilled at a later date.

R&amp;D policies for desalination technologies

AbstractIn many arid and semi‐arid regions whether or not to desalinate seawater has long been a non‐issue and policy debates are focused on the timing and extent of the desalination activities. We analyze how water scarcity and demand structure, on the one hand, and cost reduction via R&amp;D programs, on the other hand, affect the desirable development of desalination technologies and the time profiles of fresh and desalinated water supplies. We show that the optimal R&amp;D policy is of a non‐standard most rapid approach path (NSMRAP) type, under which the state of desalination technology — the accumulated learning from R&amp;D efforts — should approach a pre‐specified target process as rapidly as possible and proceed along it thereafter. The NSMRAP property enables a complete characterization of the optimal water policy. The renewable nature of the fresh water stock permits a non‐monotonic behavior of the optimal stock process: under certain conditions, the stock is depleted, to be fully or partly) refilled at a later date.

The Stock Market Perception of Industry Risk and Macroeconomic Factors: The Case of the US Water and Other Transportation Stocks

This paper attempts to uncover and compare the macroeconomic determinants of the stock returns of US listed water transportation companies to those of other transport sectors over the period July 1985 – June 1995; these involve air transportation, rail transportation and trucks. Other non-transport sectors such as electricity, gas, petroleum refining and real estate are also examined. This is done by relating cross-sectional differences in the returns of the companies in each industry to the stock market and to the following set of macroeconomic factors: (1) industrial production; (2) the term structure of interest rates; (3) oil prices; (4) consumption; and (5) inflation. Multivariate Least Square (MLSQ) regression methods are employed to estimate the above relationships. Important findings of this paper are: First, the effect of macroeconomic factors on stock returns varies among transportation industries and the other industries examined. Second, the stock market return influences the returns of all industries. Third, the market beta of the water transportation industry does not appear to be significantly higher, or lower, than the market beta of the remaining transportation, and non-transportation, sectors analysed.

The present status of artisanal fisheries of extreme Southern Brazil: an effort towards community-based management

The continental shelf of the extreme southern Brazil is one of the most productive fishing areas in Brazil. Great part of the commercial species is related to the estuary of Patos Lagoon. The estuary serves as spawning, nursery and feeding grounds for several species. The artisanal fishery in the estuarine area exists since the end of the last century but from 1982 onwards, catches have declined sharply. Nowadays, the estuarine fishery does not exist as an economic activity, except for pink shrimp ( Farfantepenaeus paulensis) and mullet ( Mugil platanus). The artisanal fishery involves about 3500 fishermen. Fisheries management in the Patos Lagoon and coastal area has been traditionally done in a top-down process: government decides and acts unilaterally. As a consequence, regulations exist only officially. In 1996 the Forum of Patos Lagoon, a multi-partner entity that includes political, economical and legal institutions, was established. This is the first initiative of the community to become part of the organization and regulation process of the fisheries in the area. The Forum activities initiatives range from evaluation of the present practices of fisheries management and enforcement, encouragement of co-operative and associated initiatives; to planning and development of activities that may lead to the possible recovery of the productive capacity of the Patos Lagoon. A new regulation for the area was produced considering, for the first time, the interest of the community. Although this represents a major step on fisheries management in the area, it resents the lack of a specific management for fisheries that exploit the same stocks in marine waters. The lack of a clear policy for the fishery sector in Brazil represents a major setback to achieve proposed goals in management.

Assessment of deep water stocks of pearl oysters at Takapoto Atoll (Tuamotu Archipelago, French Polynesia)

An assessment of natural stocks of the commercially important black pearl oyster, Pinctada margaritifera, was conducted in the lagoon of Takapoto Atoll, French Polynesia. The sampling methodology combined estimates of reef area from remote sensing, depth profiles across the lagoon, and in situ sampling using scuba. Confidence limits around estimates of mean oyster density began to stabilize after ten dives, and did not decrease further after 30. Densities of oysters increased steadily with depth, ranging from a mean of 1 per 100 m2 at 0–10 m to 8/100 m2 at 30–40 m. More than half of the stock occurred at depths greater than 30 m. The total stock was estimated to be 4.3 ± 0.67 million, equivalent to 834 metric tonnes (including shells).

Biodiversity in fresh waters – an issue of species preservation or system functioning?

Fresh waters offer intricate diversity, from small hot springs to huge floodplain systems, from temporary pools to big lakes, each containing significant proportions of the world's stock of inland water. In this collection is a great diversity of organisms, and of interesting relationships amongst them and with traditional peoples. There is thus every reason to value the diversity of freshwater systems and reasons for conserving them, from the ethical to the economic, can be listed no less than for terrestrial systems.The approaches currently used to conserve the diversity of terrestrial systems, however, may be counter-productive for the conservation of freshwater systems. These approaches include emphasis on individual, often charismatic species, or on areas of high quality that can be boundaried and protected (fortress conservation) and rest on arguments that all species must be maintained for the system to function. The current decline in world biodiversity under our increasing impact suggests that these are failing approaches even for terrestrial systems. They may be disastrous for freshwater ones.

Blue node concept: a regional water management strategy

Water scarcity is, in general, not a problem in the Netherlands. Scarcity is caused by pollution and especially non-point pollution. For the water manager the central task is the supply of water with good quality at the right time at the right place. This task depends on the demand of the different kinds of land uses, the stock of water in the area during the year, and the possibilities to separate parts of the water system with bad water quality from parts with good water quality. To do so the blue node strategy has been developed and is illustrated in this article.

A towed body designed for side-scanning hydroacoustic surveying of fish stocks in shallow waters

An aluminum towed body was designed for use in hydroacoustic surveying of fish stocks in shallow (2–10 m depth) inland waters. The design allows applications in deep (>10 m) water bodies as well. Test results showed that the towed body was a stable platform for the hydroacoustic transducer. The towed body features adjustable beam direction, allowing a side-looking as well as a vertical-looking mode. As the design of the towed body is simple, it can be easily constructed by any skilled craftsman.

Effect of parasitism on the productivity of the ommastrephid stocks in Galician waters (NW Spain): economic loss

Effect of parasitism on the productivity of the ommastrephid stocks in Galician waters (NW Spain): economic loss

Stochastic generation of meteorological variables and effects on global models of water and carbon cycles in vegetation and soils

Global models of water and carbon cycles in continental vegetation and soils are usually forced with monthly mean climatic data-sets and thus neglect day to day variations of the weather. This treatment may be justified for empirical models based on parametrizations validated at a monthly timescale. Mechanistic models handling hydrological and biological processes at much shorter timescales might, however, be largely affected by such an approximation, since the various processes described are highly nonlinear. A random generator of daily precipitations and temperatures applicable at the global scale has thus been developed from worldwide meteorological data covering 6 years of observations. The probability of a wet day is correlated to the weather encountered the previous day. The amount of precipitation, the daily mean temperature and the diurnal range of temperature are described from the statistical point of view by the cumulative distribution functions (CDF) of three random variables. The CDFs relative to temperatures are different for rainy and dry days. This stochastically generated weather field is used as input to IBM (Improved Bucket Model) and CARAIB (CARbon Assimilation In the Biosphere), two global models of respectively soil hydrology and vegetation productivity. Large differences in both the geographical distribution and the global value of soil water, vegetation productivity and carbon stocks are obtained between the model runs using monthly uniform weather on one side and randomly generated weather on the other. The main contribution to this difference at the global scale arises from the precipitation generation occurring as a result of high degree of nonlinearity of the interception scheme used in IBM.

Distribution, abundance and biology of ringed seals (&lt;i&gt;Phoca hispida&lt;/i&gt;): an overview

The ringed seal (Phoca hispida) has a circumpolar Arctic distribution. Because of its great importance to northern communities and its role as the primary food of polar bears (Ursus maritimus) the ringed seal has been studied extensively in Canada, Alaska, Russia, Svalbard and Greenland as well as in the Baltic Sea and Karelian lakes. No clear-cut boundaries are known to separate ringed seal stocks in marine waters. Adult seals are thought to be relatively sedentary, but sub-adults sometimes disperse over long distances. Stable ice with good snow cover is considered the most productive habitat although production in pack ice has been little studied. Populations appear to be structured so that immature animals and young adults are consigned to sub-optimal habitat during the spring pupping and breeding season. Annual production in ringed seal populations, defined as thepup percentage in the total population after the late winter pupping season, is probably in the order of 18-24%. Most estimates of maximum sustainable yield are in the order of 7%.The world population of ringed seals is at least a few million. Methods of abundance estimation have included aerial surveys, dog searches and remote sensing of lairs and breathing holes, acoustic monitoring, correlation analysis by reference to sizes of polar bear populations, and inference from estimated energy requirements of bear populations. Aerial strip survey has been the method of choice for estimating seal densities over large areas. Adjustment factors to account for seals not hauled out at the time of the survey, for seals that dove ahead of the aircraft, and for seals on the ice within the surveyed strip but not detected by the observers, are required for estimates of absolute abundance.Male and female ringed seals are sexually mature by 5-7 years of age (earlier at Svalbard). Pupping usually occurs in March or early April and is followed by 5-7 weeks of lactation. Breeding takes place in mid to late May, and implantation is delayed for about 3 months. In at least some parts of their range, ringed seals feed mainly on schooling gadids from late autumn through early spring andon benthic crustaceans and polar cod (Boreogadus saida) from late spring through summer. Little feeding is done during the moult, which takes place in late spring and early summer. Pelagic crustaceans offshore and mysids inshore become important prey in late summer and early autumn in some areas. Ringed seals have several natural predators, the most important of which is the polar bear in most arctic regions. Arctic foxes (Alopex lagopus) kill a large percentage of pups in someareas.From a conservation perspective, the ringed seal appears to be secure. Levels of exploitation of arctic populations have usually been considered sustainable, except in the Okhotsk Sea. Large fluctuations in production of ringed seals in the Beaufort Sea and Amundsen Gulf are thought to be driven by natural variability in environmental conditions. While concern has been expressed about thepotential impacts of industrial activity and pollution on ringed seals, such impacts have been documented only in limited areas. Because of their ubiquitous occurrence and availability for sampling, ringed seals are good subjects for monitoring contaminant trends in Arctic marine food chains.