bluuebunny/crossref_metadata_2025 huggingface dataset:
On monopolistic competition and optimal product diversity: workers' rents also matter
Authors: Picard Pierre M. , Toulemonde Eric
Published: August 2010

Abstract In the Dixit‐Stiglitz model of monopolistic competition, entry of firms is socially too small. Other authors have shown that excess entry is also a possibility with other preferences for diversity. We show that workers' rents also contribute to explain excess entry through a general equilibrium mechanism. Larger wages indeed raises the aggregate earnings and firms sales and profits, which entices too many firms to enter. We discuss the possibility of over‐provision of varieties by comparing the equilibrium to unconstrained and constrained social optima and to other regulatory frameworks where wages are not controlled.
Cross‐border acquisitions and taxes: efficiency and tax revenues
Authors: Norbäck Pehr‐Johan , Persson Lars , Vlachos Jonas
Published: August 2010

AbstractWe develop a theoretical oligopoly model to study how international differences in profit and capital gains taxes affect foreign acquisitions. Reductions in foreign profit taxes tend to trigger inefficient foreign acquisitions, while reductions in foreign capital gains taxes may trigger efficient foreign acquisitions. Foreign acquisitions can increase domestic tax revenues even when profit taxes are evaded. The reason is that bidding competition between foreign firms ensures that all benefits from the acquisition, including tax advantages, are captured by a domestic seller paying capital gains taxes. Tax code issues, such as the treatment of goodwill, are shown to affect the pattern of foreign acquisitions.
U.S. trade remedy law and agriculture: trade diversion and investigation effects
Authors: Carter Colin A. , Gunning‐Trant Caroline
Published: August 2010

Abstract We study U.S. agricultural antidumping and countervailing duty cases from 1980 to 2005, and gauge the effectiveness of trade remedy law as a form of protection. The purpose is to measure the resulting investigation and trade diversion effects. Previous research on trade in manufactured products has shown that the domestic protection offered by AD and CV duties is largely offset by trade diversion. In contrast, we find that for agriculture, trade diversion is relatively unimportant. So AD and CVD cases are very effective forms of protection for U.S. agriculture.
National champions and globalization
Authors: Südekum Jens
Published: August 2010

Abstract In this paper, we offer an explanation why globalization (falling trade costs) may increase the government incentive to block foreign takeover of domestic firms and increase its incentive to allow mergers among national firms. This creation of ‘national champions’ occurs not only because the government may have a bias against foreign takeover, but also because consumer welfare gains associated with foreign acquisitions decrease with globalization. Endogenizing the government bias through lobbying efforts of the domestic firms, the paper shows that the bias does not need to be very strong before the government promotes domestic champions provided that barriers to trade are low.
Information technology and efficiency in trucking
Authors: Barla Philippe , Bolduc Denis , Boucher Nathalie , Watters Jonathan
Published: August 2010

Abstract We develop an econometric model to estimate the impact of Electronic Vehicle Management Systems (EVMS) on the load factor (LF) of heavy trucks. This technology is supposed to improve capacity utilization. The model is estimated on the Quebec subsample of the 1999 National Roadside Survey. The LF is explained as a function of truck, trip, and carrier characteristics. We show that the use of EVMS results in an increase of 16 percentage points of LF on backhaul trips. However, we also find that there is a rebound effect on fronthaul movements, with a reduction of LF by about 7.6 percentage points.
A bioeconomic view of the Neolithic transition to agriculture
Authors: Robson Arthur J.
Published: August 2010

Abstract Adoption of agriculture at the expense of hunting and gathering was the dramatic precondition for all modern civilization. Recent data suggest that, because of this transition, humans initially were more disease prone, smaller, less nourished, and shorter‐lived. To explain why individuals chose agriculture over hunting and gathering, this paper develops a simple model of the evolution of preferences over the quality and quantity of children, as would have been generated by our long history as a species. These preferences would have induced the choice of agriculture, but also would have led to these otherwise puzzling health effects.
Equity‐regarding poverty measures: differences in needs and the role of equivalence scales
Authors: Ebert Udo
Published: August 2010

Abstract The paper investigates the definition of equity‐regarding poverty measures when there are different household types in the population. It demonstrates the implications of a between‐type regressive transfer principle for poverty measures, for the choice of poverty lines, and for the measurement of living standard. The role of equivalence scales, which are popular in empirical work on poverty measurement, is clarified.
Measuring the gains from trade under monopolistic competition
Authors: Feenstra Robert C.
Published: August 2010

Abstract Three sources of gains from trade under monopolistic competition are (i) new import varieties available to consumers; (ii) enhanced efficiency as more productive firms begin exporting and less productive firms exit; (iii) reduced markups charged by firms due to import competition. The first source of gains can be measured as new goods in a CES utility function for consumers. We argue that the second source is formally analogous to the producer gain from new goods, with a constant‐elasticity transformation curve for the economy. We suggest that the third source of gain can be measured using a translog expenditure function for consumers, which, in contrast to the CES case, allows for finite reservation prices for new goods and endogenous markups.
Hemolysis and thrombocytopenia following oxaliplatin administration
Authors: LE Brian HC , JUNEJA Surender , GIBBS Peter
Published: August 2010

Oxaliplatin is a platinum derivative with an overall excellent safety profile that has a major role in the treatment of colorectal cancer. With a proven role now in the adjuvant setting, rare but potentially life‐threatening toxicities become a more significant issue. We report here a case of significant postinfusion hemolysis and thrombocytopenia in a patient undergoing adjuvant chemotherapy for stage III colon cancer, and review the literature. Six cases of hemolysis following oxaliplatin treatment have previously been reported, all in the setting of advanced colorectal cancer, with one case resulting in death. In three of the seven reports (including the present case), warning signs of low grade hemolysis were apparent during preceding cycles, with fever and/or back pain during the infusion being the most common feature. Our case appears to be the first reported with a direct antiglobulin test‐negative hemolysis with thrombocytopenia, with each of the previous reports postulating an autoimmune basis. Hemolysis and/or thrombocytopenia are potentially life‐threatening complications of oxaliplatin chemotherapy. With the increasing use of oxaliplatin in the adjuvant setting, clinicians need to be aware of this entity and the possible clinical warning signs that may be evident in preceding cycles.
Crossing experiments and behavioral observations reveal reproductive incompatibility among three putative species of the whitefly Bemisia tabaci
Authors: Wang Peng , Ruan Yong‐Ming , Liu Shu‐Sheng
Published: August 2010

Abstract  The whitefly Bemisia tabaci has a global distribution and extensive genetic diversity. Recent phylogenetic analyses as well as crossing experiments suggest that B. tabaci is a complex composed of > 20 cryptic species, but more crossing studies are required to examine the reproductive compatibility among the putative species and thus further clarify the systematics of this species complex. We conducted crossing experiments and behavioral observations to investigate the reproductive compatibility between the Mediterranean, Asia II 3, and Asia II 1 putative species of B. tabaci collected from Zhejiang, China. Female progeny were never produced in inter‐species crosses, demonstrating a lack of egg fertilization; while 55%–75% females were produced in all the intra‐species treatments. Continuous behavioral observations showed that frequent courtship events occurred in both intra‐species treatments and inter‐putative species crosses. However, copulation events occurred only in the three intra‐species treatments with one exception: that one copulation event occurred between Asia II 3 and Mediterranean in the crosses where two cohorts of females and males of different putative species were enclosed together in a small arena but were not allowed access to their intra‐specific mates for a long period of time. These data demonstrated complete reproductive isolation between the Mediterranean, Asia II 3, and Asia II 1 putative species, and further showed that the isolation is due to lack of copulation. Demonstration of reproductive isolation between the Mediterranean and two indigenous putative species from China provides further evidence for the existence of cryptic species within the B. tabaci complex.
DEVELOPMENT OF AQUACULTURE IN AN ISLAND COMMUNITY (GUAM, MARIANA ISLANDS)1
Authors: FitzGerald William J. , Nelson Stephen G.
Published: August 2010

Guam' aquaculture program was initiated in 1973. At that time government operated experimental demonstration ponds were stocked with a variety of species in order to obtain growth data under local climatic conditions and to determine which show the greatest promise for use in aquaculture. The species which were most promising were the eel (Anguilla japonica) and the freshwater prawn (Macrobrachium rosenbergii).

At present the culture of prawn, eel, hybrid tilapia, and freshwater turtle is being conducted on a small scale. The majority of the prawn ponds are managed as polyculture systems with several species of Chinese carp cultured as secondary species. Several marine and freshwater species show potential for aquaculture on Guam in the future. The merits of these species are reviewed.
EFFECTS OF FLUCTUATING AND CONSTANT TEMPERATURES AND CHEMICALS IN THERMAL EFFLUENT ON GROWTH AND SURVIVAL OF THE AMERICAN LOBSTER (Homarus americanus)1
Authors: Ford Richard F. , Felix John R. , Johnson Richard L. , Carlberg James M. , Van O1st Jon C.
Published: August 2010

The effects of long‐term exposure to a fluctuating temperature regime typical of that produced by coastal electric generating stations were investigated for juvenile Homarus americanus held in individual rearing containers. Juveniles reared in a 15–22°C daily temperature fluctuation for 126 days had significantly slower growth than those reared at a constant 22°C. They also had significantly higher mortality and less resistance to a high stress temperature (31°C) than those reared at the constant temperature. Exposure to fluctuating temperatures for 1–2 weeks had no evident effect on growth and survival, suggesting that such short‐term exposures would not be harmful in commercial culture. Related experiments were conducted to assess effects of thermal effluent water chemistry and 4 constant temperatures on growth and survival of larvae and juveniles (Stages I‐XI). There were no significant differences in growth and survival among lobsters held in either thermal effluent or intake water at a given temperature (16, 20, 24, or 26°C), indicating that effluent water chemistry had no apparent effects. There were significant differences in growth of both larvae and juveniles held at the 4 constant temperatures. Survival of juvenile lobsters was not affected significantly by temperature, while that of larvae was. Juvenile lobsters molted more frequently at successively higher temperatures. However, these individuals were not larger than those produced by slower molting at 20°C. This was attributed to absence of a corresponding increase in feeding rate and the relatively high oxygen consumption rates observed at 24 and 26°C.
POLYCULTURE OF Tilapia aurea AND Macrobrachium rosenbergii IN TEXAS1
Authors: Brick Robert W. , Stickney Robert R.
Published: August 2010

A study of polyculture was initiated at the Aquaculture Research Center, Texas A&M University, using Macrobrachium rosenbergii and monosex Tilapia aurea. These species were selected because of their current popularity in aquaculture and because their food preferences and patterns of behavior indicated no reason to expect serious competition. Shrimp were stocked at 11,000 per ha with or without fish (2000 per ha) for observation from June 1 to October 15. The effect of pre‐treatment of ponds with inorganic fertilizer was also studied. Each pond was supplied with equal amounts of Experimental Marine Ration 25 (Ralston‐Purina Co.).

Mean survival of fish and shrimp was 96 and 95.7%, respectively. Fish grew to a mean weight of 182 g while shrimp in polyculture grew to 24.5 g and 27.5 g in monoculture. Average daily growth increments were 1.37 g for fish and 0.21 g for shrimp.

Neither growth nor survival of fish or shrimp were influenced by pre‐treatment of ponds with fertilizer in this study.
FEEDING AND AGGRESSIVE BEHAVIOR OF ATLANTIC CROAKER, BLACK DRUM, AND STRIPED MULLET IN MONOCULTURE AND POLYCULTURE
Authors: Gibbard Gail L. , Strawn Kirk , Aldrich David V.
Published: August 2010

Behavior of Atlantic croaker (Micropogon undulatus), black drum (Pogonias cromis), and striped mullet (Mugil cephalus) was observed in monoculture and polyculture situations. Dominance hierarchies, feeding and aggressive behavior were established for the three species in each culture situation. All fish were acclimated to tanks and artificial food, and were fed a limited amount of food. Four individuals of each species were observed over 4 consecutive days in monoculture. Four striped mullet each were then placed with the Atlantic croaker and black drum.

Competition for food and space resulted in higher feeding rates in all three species. Aggression also increased in Atlantic croaker and black drum. Atlantic croaker became territorial in polyculture. In general, growth and condition of a fish was directly correlated with its position in the dominance hierarchy.
FACTORS AFFECTING GROWTH AND SURVIVAL OF COHO SALMON (Oncorhynchus kisutch) AND CHINOOK SALMON (O. tshawytscha) IN SALTWATER NET‐PENS IN PUGET SOUND
Authors: Mahnken Conrad V. W. , Waknitz F. William
Published: August 2010

Experimental marine net‐pen systems for the culture of Pacific salmon have been developed in the United States and Canada and have resulted in the establishment of fish farms in Washington, Alaska, Maine, and British Columbia. Fish farmers have encountered biological problems that constrain production through decreased growth and survival. These factors include: feed amounts (ration), dissolved oxygen levels and rearing densities, saltwater adaptation, physiological stage of smoltification, and disease. This paper discusses the relative severity of these problems and current practices for solving them.
A LABORATORY INVESTIGATION OF Macrobrachium rosenbergii NURSERY PRODUCTION1
Authors: Kneale Douglas C. , Wang Jaw‐Kai
Published: August 2010

Three experiments were performed to evaluate the effect of temperature, habitat, and stocking density on the survival and growth of juvenile Macrobrachium rosenbergii. Experiment 1 was initiated with 0.02 g prawns stocked at densities of 900 and 1200 PL/m2 for levels of one and three habitats per tank. Experiment 2 was stocked with 0.01 g prawns at densities of 1200 and 1500 PL/m2 and were maintained at 24 and 28°C. Concurrently, experiment 3 evaluated stocking densities of 150, 300, and 600 PL/m2 at 28°C. Experiments were conducted over a period of 8–10 weeks.

Experiments 1 and 2 clearly showed a region where there was a significant increase in mortality rate. It was noted that the onset of the mortality shift, referred to as the breakpoint, generally occurred when the prawns were between 8 and 9 weeks old. The breakpoint was evident at all levels of temperature and habitat, and at stocking densities above 900 prawns/m2. The occurrence of breakpoint did not seem to be related to mean weight or biomass.

Percent survival at the end of the experimental periods was generally inversely proportional to the initial stocking density, showing a high of 84% at 150 PL/m2 and a low of 39% at 1500 PL/m2. Overall growth was greater for stocking densities at or below 600 PL/m2 (mean weight gain 0.8–1.0 g) as compared to stocking densities above this point (0.4 g). Growth rate was not significantly different between densities of 1200 and 1500 PL/m2. At 24°C the average survival was 78%, significantly greater than 43% at 28°C. Temperature also significantly increased overall growth, yielding on the average 0.41 g at 28°C versus 0.23 g at 24°C. The number of habitats per tank did not appear to influence survivability, however, growth may be affected by the number of habitats per tank.
A METHOD FOR ARTIFICIAL INSEMINATION OF Macrobrachium PRAWNS AND ITS POTENTIAL USE IN INHERITANCE AND HYBRIDIZATION STUDIES1
Authors: Sandifer Paul A. , Smith Theodore I. J.
Published: August 2010

A simple method for artificial insemination of Macrobrachium prawns is described and observations on breeding behavior, spermatophores and spawning are reported. The insemination procedure involves mechanical extrusion and attachment of sperm masses and has proved successful for intraspecific crosses of M. rosenbergii and M. acanthurus. Further, more than one female can be bred simultaneously by using sperm from a single male, an important consideration for inheritance studies. The following interspecific crosses also have been attempted with this method but without success: M. acanthurus ♂ x M. rosenbergii ♀, M. rosenbergii ♂ x M. acanthurus ♀, M. acanthurus ♂ x M. ohione ♀, M. rosenbergii ♂ x M. ohione ♀, and M. ohione ♂ x M. rosenbergii ♀. Manually placed sperm masses were retained through spawning in a few of the hybridization attempts, but fertilization was not obtained. However, since only a relatively small number of crosses have been attempted, additional efforts in this area appear warranted. Specifically, we believe that trials with more closely related species than those tested to date might prove more fruitful. Also, the potential use of this procedure in captive breeding or hybridization of other species of shrimp is noted.
FATTY ACID CHANGES DURING LARVAL DEVELOPMENT OF Penaeus setiferus
Authors: Ward D. G. , Middleditch B. S. , Missler S. R. , Lawrence A. L.
Published: August 2010

The fatty acid compositions for five stages of development (egg, nauplius, protozoea, mysis, and one‐to‐two day postlarva) of the shrimp Penaeus setiferus were determined. Of twelve fatty acids identified, the four major fatty acids in the egg and one‐to‐two day postlarva were 16:1, 16:0, 18:1, and 20:4, and 16:0, 18:1, 20:4 and 22:6, respectively. On a per‐unit weight basis, the 16:1, 16:0, 18:1 and 20:4 fatty acids decreased by 83, 47, 44, and 18% respectively from egg to one‐to‐two day postlarva. However, there was a 66% increase in the amount of 22:6 fatty acid on a per‐unit dry weight basis from egg to one‐to‐two day postlarva. On a per animal basis, the largest increases were obtained for the 16:0, 18:0, 18:1, 20:4 and 22:6 fatty acids from the protozoea to one‐to‐two day postlarva stages of development. The largest decreases for fatty acids on a per animal basis were obtained for 16:1, 16:0, 18:1, and 18:0 from the egg to nauplius stage. The significance of these results to understanding shrimp larval nutrition is discussed.
EXPERIMENTAL REARING OF PENAEID SHRIMPS IN KUWAIT
Authors: Farmer A. S. D.
Published: August 2010

Since 1972 there has been a continuous research program at the Kuwait Institute for Scientific Research to develop techniques for rearing penaeid shrimps for restocking purposes and also for subsequent commercial cultivation to market size. During this period research has been concentrated on Penaeus semisulcatus, the major commercial species in the Arabian Gulf, although Penaeus japonicus and Metapenaeus affinis have also been reared. A summary of the experimental results and the economic feasibility for commercial production in Kuwait is provided.
TOXICITY OF TEN CHEMICALS COMMONLY USED IN AQUACULTURE TO THE BLACK EEL STAGE OF THE AMERICAN EEL1
Authors: Hinton Michael J. , Eversole Arnold G.
Published: August 2010

Acute, 96‐hour toxicity tests were conducted to determine the resistance of the black eel stage of the American eel (Anguilla rostrata) to several chemicals used in aquaculture. Static tests were conducted at 22°C in deionized water reconstituted to a hardness of 40–48 mg/liter, an alkalinity of 30–35 mg/liter, and pH of 7.2–7.6. A 96‐hour LC50 value was calculated for each chemical tested. Chemicals tested and their 96‐hour LC50 values are: malachite green, 0.54 mg/liter; potassium permanganate, 4.86 mg/liter; salt, 21.45 g/liter; formalin, 224.49 mg/liter; Dylox, 1.32 mg/liter; Furanace, 0.96 mg/liter; antimycin A, 0.28 μg/liter; Noxfish, 50.49 μg/liter; copper sulfate, 3.20 mg/liter; and Diquat, 55.44 mg/liter.
LENGTH‐WEIGHT RELATIONS FOR SEVERAL SPECIES OF PENAEID SHRIMP CULTURED IN PONDS NEAR CORPUS CHRISTI, TEXAS
Authors: Hutchins David L. , Chamberlain George W. , Parker Jack C.
Published: August 2010

Length measurements are relatively easier to obtain than weight measurements. Length‐weight relationships provide a means of estimating weight based on length. Linear regressions using the model W = aLb were calculated from paired length and weight measurements (1972 through 1979) of Penaeus duorarum, P. occidentalis, P. setiferus, P. stylirostris, and P. vannamei cultured at the Texas A&M Shrimp Mariculture facility near Corpus Christi, Texas. Length‐frequency distributions and regression formulae for predicting weights from lengths are presented for each species.
ANALYSIS OF METHODS FOR THE CULTURE OF Crassostrea virginica IN NEW ENGLAND
Authors: Matthiessen G. C. , Smith L. J.
Published: August 2010

Intensive use of the New England shoreline by competing interests severely limits the area available for shellfish culture. As a result, more recent production systems attempt to minimize the area required for culture while maximizing the likelihood of survival.

Various methods of culture tested during recent years are discussed, with specific reference to the American oyster (Crassostrea virginica). The technical and economic advantages and disadvantages of each of these methods are reviewed and compared.
A COMPARATIVE STUDY OF A SALTWATER IMPOUNDMENT AND ITS ADJACENT TIDAL CREEK PERTINENT TO CULTURE OF Crassostrea virginica (GMELIN)
Authors: Anderson William D.
Published: August 2010

Certain physical, chemical and biological characteristics associated with the culture of subtidal Crassostrea virginica were assessed in a saltwater impoundment and its adjacent tidal feeder creek. Large seed oysters (initial x̄ = 57.3 mm) were transferred from a polluted estuary of Charleston Harbor to floating, mid‐water, and bottom hardware cloth trays (200/tray) in a 4‐ha pond. Identical trays at comparable depths were placed in the tidal creek and each location was sampled monthly for growth and survival. Surface and bottom water samples were collected weekly throughout the study and hourly during four seasonal 25‐hour stations. Standard hydrographic parameters (temperature, salinity, pH, dissolved oxygen, light penetration, and turbidity) were measured along with chlorophyll a, phytoplankton, dissolved and particulate carbohydrates, nutrients (nitrates, nitrites, orthophosphates and silicates), current velocities, and thioglycollate assays for Perkinsus marinus.

Over a 12‐month period, oyster growth was significantly (α = 0.01) greater in the pond than in the creek. Best growth in the impoundment occurred in floating trays, poorest in bottom trays. Growth and survival were higher in winter and lower in summer in both environments. Higher levels of chlorophyll a, carbohydrates, pH, and dissolved oxygen were consistently observed in the impoundment. Lower comparative nutrient values in the pond together with higher biomass levels indicated a more favorable environment for autotrophic production. Greater oyster production in the pond was directly related to a higher instantaneous biomass maintained throughout the year. This relationship was supported by indications of an inverse correlation between nutrient concentrations and the instantaneous biomass. Nutrient and biomass data indicated an apparent NO3‐ limited system.
AMINO ACID SUPPLEMENTATION OF FEED PELLETS OF THE GIANT SHRIMP (Macrobrachium rosenbergii)
Authors: Farmanfarmaian A. , Lauterio T.
Published: August 2010

Amino acids reported to be essential for the giant shrimp (Macrobrachium rosenbergii) and other crustacea have been added at a 1% level by weight to Purina Marine Ration repelletized with binders. Separate batches of repelletized feed were made as follows: control without supplement; isonitrogenous control with 1% ovalbumin supplement, or with 1% of the natural enantiomorph of arginine, lysine, phenylalanine, histidine, leucine, isoleucine, methionine, or threonine separately supplemented. Pellets were fed to individual animals in parallel experiments under precisely controlled and defined environmental and density conditions. Growth rates and conversion ratios and indices were measured as previously reported. Arginine, phenylalanine, leucine, and isoleucine stimulated the growth‐conversion index while the other amino acids tested had no significant effect on this index and appeared to be available at a sufficient level in the commercial pellet.
A PHYSIOLOGICAL APPROACH TO THE STUDY OF GROWTH AND BIOENERGETICS IN THE FRESHWATER SHRIMP Macrobrachium rosenbergii
Authors: III Henry C. Clifford , Brick Robert W.
Published: August 2010

Oxygen consumption, ninhydrin‐positive nitrogen excretion and carbon dioxide production were monitored in juvenile Macrobrachium rosenbergii fed a series of experimental diets containing variable levels of protein, lipid and carbohydrate. Using respiratory quotient and nitrogen excretion data, metabolic substrate ratios and oxycalorific coefficients were derived for transformation of metabolic observations to a caloric basis. Energy partitioning and growth were evaluated for each dietary treatment by means of individual energy and nitrogen balances generated from physiological rate functions.

Measurements of nitrogen excretion and corresponding metabolic substrate ratios indicate that the protein‐sparing effect of non‐protein energy sources is maximized at a lipid:carbohydrate ratio of 1:4. Analysis of energy and nitrogen budgets also confirms this relationship. Nitrogen retention in the experimental animals was found to be positively correlated with dietary protein with a slight decline and leveling off at 30% protein. In contrast, protein content operated in an inverse manner upon physiological energetics; maximum caloric growth occurred at lower protein level. Based on this inverse relationship, it is concluded that optimal conditions for growth are achieved with a 25% protein diet containing a lipid:carbohydrate ratio of 1:4.
EFFECT OF HARVEST RATE, WASTE LOADING, AND STOCKING DENSITY ON THE YIELD OF DUCKWEEDS
Authors: Said M. Zaki M. , Culley Dudley D. , Standifer Leon C. , Epps Ernest A. , Myers Robert W. , Boney Steve A.
Published: August 2010

In an outdoor tank culture system with 10 to 20 g/liter fresh dairy cattle manure dilutions (ca 60 to 120 mg/liter TKN), maximum growth of duckweed (Spirodela polyrhiza) was obtained when harvested at 6‐day intervals. An initial stocking of 70 g fresh duckweed/0.14 m2 (505 g/m2) gave the highest yield when the excess fresh biomass (34.4 g) was harvested daily or 33% of the standing stock. The extrapolated yield of dry duckweed harvested daily was 14.9 g/m2/day and was 58% higher than one weekly harvest. Removal of excess growth daily gave higher yields than removing half the standing crop at doubling periods exceeding 2 days. Nitrogen, phosphorus, and potassium content of duckweed increased as water nutrients increased. The maximum dry weight values were: nitrogen, 6.96%; phosphorus, 1.50%; and potassium, 3.50%. The highest dry duckweed crude protein value recorded was 43.5% and the mean was 38.2% when the plants were cultured on 10 g fresh manure/liter of solution. Higher protein values were correlated with lower standing crop. Comparisons between the tank culture system and lagoon studies using mixed species culture are discussed. Extrapolation of lagoon data showed an annual dry weight mean yield of 1.76 kg/m2 and a maximum yield of 2.2 kg/m2 when one half of the plants were harvested weekly. Annually, in comparison 4.4 kg/m2 of S. polyrhiza were estimated from daily harvests in the tank system with corrections made for seasonal effects. Nutrient content of the duckweeds were similar under the two systems. Under both systems aeration did not increase yields over non‐aerated tests.
PUBLIC HEALTH IMPLICATIONS OF ENZYME HYDROLYSIS FISH PROTEIN CONCENTRATION AND WASTE WATER BASED AQUACULTURE
Authors: Simon Robert D. , DiSalvo Louis H. , Guard Harold E.
Published: August 2010

The production of fish protein concentrate and the aquaculture of fish in waste waters are two ancient technologies. Modern use of these technologies demands examination of their public health implications as they are adapted to modern needs of food production and waste processing. Though the ponding of wastes to meet safe discharge requirements has been observed to be efficient and economic, both chemical and microbiological factors potentially interfere with using waste waters to produce protein supplements for human consumption. Application of one or more food engineering processes could relieve the inherent problems of coordinating waste water management and protein production.

The fish protein concentration process evaluated in this study is based on a recently developed food engineering process. This process was investigated because of its low cost and the functional properties of the final product.

The literature investigation indicates microbiological agents and microbial toxins of public health concern will be destroyed during the fish protein concentration process investigated and prevented from forming in the final product. Laboratory investigations undertaken in this research document that the heavy metals cadmium, chromium, copper, lead and zinc concentrated in the final product on the average 15% or less than the maximum concentration that could have occurred (maximum concentration is the initial burden of a metal multiplied by the factor by which the raw tissue is concentrated). Information available suggests that the method of fish protein concentration investigated in this study concentrates the heavy metals less than similar processes reported previously.

It is concluded that if the final fish protein concentrate is used as a supplemental protein, fish from waste waters can be used as the raw product in the process. Ideally, waste waters low in or devoid of industrial pollutatants should be chosen for fish culture.
STAGGERED STOCKING OF Penaeus stylirostris IN BRACKISH‐WATER PONDS RECEIVING POWER PLANT COOLING WATER
Authors: Ojeda Jane W. , Aldrich David V. , Strawn Kirk
Published: August 2010

Blue shrimp (Penaeus stylirostris) were cultured in 11 0.1‐ha earthen ponds during the spring and summer of 1979 to compare conventional and staggered stocking techniques. Three batches of post‐larval shrimp (stocks I, II and III) were stocked at intervals of about 3.5 weeks. Seven thousand eight hundred stock I shrimp were introduced into each of 3 ponds, 7,800 stock II shrimp into each of 3 more ponds, and 2,435 stock III shrimp into each of 2 more ponds. Two additional ponds received approximately equal increments of the 3 batches to reach final stocking densities of 7,635. The final pond received only the first 2 increments for a final stocking density of 5,200.

Survival and yield ranges were 18.4–63.2% and 3.3–45.0 kg/0.1 ha, respectively. Ponds that received 3 stocking increments had mean survival rates and yields (36.8%, 32.3 kg/0.1 ha) higher than expected values (32.2%, 22.5 kg/0.1 ha) calculated using the mean values from the single‐stocked control ponds.

Salinities were near 2 ppt (range, 1–6 ppt) for most of the 53‐ to 106‐day culture period. This may have depressed shrimp growth.
THE LARVAL CULTURE OFPenaeus stylirostrisUSING MODIFICATIONS OF THE GALVESTON LABORATORY TECHNIQUE1
Authors: Mock C. R. , Revera D. B. , Fontaine C. T.
Published: August 2010

Preliminary observations on the larval culture ofPenaeus stylirostrisusing modifications of the “Galveston Laboratory” technique included: 1) installing airlift pumps in spawning tanks; 2) treating water with ethylenedinitrilo tetra‐acetic acid, disodium salt (EDTA); 3) using small UV germicidal lamps to eliminate contaminationg dinofla‐gellates from hatchery tanks; and 4) testing the use of two forms of bakers' yeast (Saccharomyces cerevisiae), compressed cake and active dry yeast (ADY), as replacement for frozen algae as larval foodstuff.

The design of the spawning tank helped to increase the hatching of fertile eggs from 0% to 80%. It was shown by bioassay testing that the UV light eliminated the dinoflagellate and that direct treatment of hatchery water with the germicidal lamp had no apparent detrimental effect on foodstuff or shrimp larvae. Bakers' ADY appeared to be more readily accepted than compressed yeast cake by shrimp larvae as foodstuff and was easier to prepare and monitor. Although yeast was an efficient replacement for frozen algae as foodstuff for larval shrimp, it took slightly longer for the total populations to metamorphose to post‐larvae when yeast was fed.
COMPARATIVE GROWTH AND SURVIVAL OF BROWN SHRIMP CULTURED WITH FLORIDA POMPANO, BLACK DRUM AND STRIPED MULLET
Authors: Rossberg Karen S. , Strawn R. Kirk
Published: August 2010

Brown shrimp (Penaeus aztecus) were grown at densities of 3000/ha in polyculture with fish in flow‐through 0.1 ha ponds. Shrimp, 104.8 † 6.81 mm in total length, were stocked with Florida pompano (Trachinotus carolinus), 67.6 † 9.32 mm in standard length (SL); Florida pompano, 58.0 † 6.13 mm SL, and black drum (Pogonias cromis), 91.9 † 11.17 mm SL; black drum, 86.3 † 10.65 mm SL; and black drum, 93.7 † 7.92 mm SL, and striped mullet (Mugil cephalus), 74.5 † 26.36 mm SL. Densities were 5000/ha for Florida pompano and black drum, and 500/ha for striped mullet. Shrimp survival ranged from 19.0 to 63.3%. Average survivals, all treatments, were poorest with Florida pompano and best with black drum in fish monocultures. Growth was excellent, averaging 0.17 g/day and similar with all fish species and combinations.
INDUCED FEEDING AND GROWTH ENHANCEMENT OF BLACK DRUM WHEN CULTURED WITH FLORIDA POMPANO AND WITH STRIPED MULLET
Authors: Rossberg Karen S. , Strawn R. Kirk
Published: August 2010

Age O black drum (Pogonias cromis) were stocked in polyculture with age O Florida pompano (Trachinotus carolinus); age O striped mullet (Mugil cephalus); and in monoculture in 0.1 ha flow‐through ponds. Densities were 5,000 fish/ha each for Florida pompano and black drum and 500 fish/ha for striped mullet. Pompano were harvested after 5 months of culture leaving black drum counterparts to continue in monoculture. After approximately 278 days, production of drum was 66% greater when initially grown with pompano for 145 days than for those maintained in monoculture throughout the study. The small number of striped mullet served as feeding stimuli for black drum, thus improving production 40% over drum kept in monoculture.
SOME ASPECTS OF THE CONTROLLED PRODUCTION OF THE BAY SCALLOP (Argopecten irradians)
Authors: Rhodes Edwin W. , Widman James C.
Published: August 2010

Methods for the intermediate and final grow‐out of hatchery‐reared bay scallops are presented. Hatchery seed 5 mm in length can be efficiently grown to 20 mm in less than 2 months in a pumped raceway system at ambient temperature and phytoplankton levels between June and October. The maximum carrying capacity of the raceways at a seawater flow of 50 liters/min is about 5 liters of scallop biomass. At 10 liters of scallops per raceway phytoplankton availability is limiting.

Growth is not affected by scallop densities as high as 1.8 liters/ m2. Raceway depth does not influence growth. Suspending small scallops in a net in the raceway does not improve growth.

Seed scallops stocked at various densities in lantern nets deployed in Long Island Sound grow rapidly. Densities up to 1000/m2 seem feasible and this grow‐out method may prove to be cost‐effective.
ANTIPROTOZOAN IMMUNIZATION STUDIES IN THE CHANNEL CATFISH, Ictalurus punctatus
Authors: Goven Beverly A. , Dawe Donald L. , Gratzek John B.
Published: August 2010

The antigenic relation between Tetrahymena pyriformis (Ehrenberg, 1830) Lwoff, 1947 and Ichthyophthirius multifiliis Fouquet 1876 was investigated using various in vitro immunologic tests. Tomites of I. multifiliis exposed to dilutions of rabbit anti‐tetrahymena serum were immobilized in 24 hours. Tetrahymena in this test system were agglutinated at low dilutions and immobilized at higher dilutions. Using an indirect fluorescent antibody test, both organisms showed fluorescence when treated with either rabbit anti‐tetrahymena serum or anti‐tomite serium. In heterologous crosses, titers of 1:1024 were obtained using the passive hemagglutination test. These results indicate than an antigenic relationship does exist between these two organisms, cross‐reacting antigens appearing to be localized on the cilia.

Channel catfish Ictalurus punctatus Rafinesque were immunized with ciliary and whole cell preparations of I. multifiliis and subsequently challenged with I. multifiliis. Similar T. pyriformis preparations were used to determine if this heterologous immunization would elicit a protective immune response against I. multifiliis infestation. Results indicate that various degrees of protective immunity were induced with all antigen preparations. T. pyriformis ciliary antigens provided the greatest degree of protection. Four doses of antigen, ranging from 25 μg to 1.0 μg were used to determine if the immunizing dosage influenced the degree of protective immunity conferred.
GROWTH AND CONVERSION EFFICIENCY OF JUVENILE AMERICAN LOBSTERS (Homarus americanus) IN RELATION TO TEMPERATURE AND FEEDING LEVEL
Authors: Bartley Devin M. , Carlberg James M. , Van Olst Jon C. , Ford Richard F.
Published: August 2010

Juvenile lobsters were maintained in recirculating seawater systems at temperatures of 10, 15, 20 and 25°C. At each constant temperature, groups of 25 lobsters were fed rations of 0, 1, 2 and 4% of their body weight per day; 25 lobsters were also fed to excess at each temperature.

For the starvation groups, time to 50% mortality (LT50) varied inversely with temperature. At 10°C the LT50 was 114 days while at 20°C it was only 47 days. Survival was high in all cases except for those groups starved or fed to excess, the latter indicating toxic effects from the decomposition of unconsumed food. Growth was exponential as described by the general growth equation W = αekt where W is weight, t is time and α and k are fitted parameters. Specific growth rate ranged from a low of 0.43% increase wet body weight per day at 10°C and a 1% feeding level to 1.38% at 25°C and a 4% feeding level. Gross conversion efficiency (increase in wet weight divided by dry weight of food fed) ranged from 30% at 10°C and a 4% feeding level to 91% at 15°C and a 1% feeding level. Efficiency values decreased with age. Feeding levels promoting most efficient growth and maximum growth increased with increasing temperature. The optimum combination of temperature and feeding level appears to be near 20°C and 2% of body weight.
EFFECTS OF DIETARY FIBER ON GROWTH, ASSIMILATION AND CELLULASE ACTIVITY OF THE PRAWN (Macrobrachium rosenbergii)1
Authors: Fair P. H. , Fortner A. R. , Millikin M. R. , Sick L. V.
Published: August 2010

Cellulose fiber comprising up to 30% of an isonitrogenous series of diets (0, 5, 15 and 30% fiber concentration) did not suppress growth of prawn having average initial weights of 0.08 ± 0.002 g over a 12‐week period. In addition, dietary fiber concentrations of 5 and 20% were found to stimulate growth over an 8‐week period among prawn having initial average weights of 1.48 ± 0.054 g, as opposed to 0% fiber concentration, which had no significant effect on growth.

Cellulase activity measured in hepatopancreas tissues by viscometric techniques was shown to be positive with a six‐fold increase in activity occurring in adult prawn (11 ± 1.16 g) when compared to smaller prawn (1 ± 0.06 g). However, activity in both sizes of prawn was not found to be proportional to increases in dietary fiber concentrations. Total organic carbon assimilation decreased while nitrogen assimilation efficiency increased in response to increasing dietary fiber concentration. Results from the present study indicated that use of dietary fiber may make a significant contribution to commercial formulations of cost‐effective crustacean diets.
A QUANTITATIVE ANALYSIS OF DIGESTIVE ENZYMES FOR THE FRESHWATER PRAWN Macrobrachium rosenbergii
Authors: Lee Phillip G. , Blake Norman J. , Rodrick Gary E.
Published: August 2010

The specific activities of 10 different digestive enzymes, taken from the hepatopancreas of the freshwater prawn (Macrobrachium rosenbergii), were determined. The prawns were 70–110 mm in length and were fed Purina Marine Ration #25 daily.

The extracts of M. rosenbergii hepatopancreas exhibited significant activity for the following enzymes: amylase, trypsin, chymotrypsin, pepsin, carboxypeptidase A and B, and leucine aminopeptidase. In addition, the lipolytic enzymes exhibited high esterase activity and only a trace of lipase activity.

From this enzyme profile M. rosenbergii is appropriately classified an omnivore. The levels of specific activity reveal the prawn's ability to effectively hydrolyze Purina Marine Ration #25 and further implies that increased protein and starch levels would still be hydrolyzed efficiently. Although individual differences in activities were demonstrated, no direct relationship to sex or size could be detected.

In summary, studies concerning the digestive physiology of M. rosenbergii may provide a more logical and efficient approach to its dietary requirements for mariculture.
CALCIUM AND pH REQUIREMENTS IN THE CULTURE OF BULLFROG (Rana catesbeiana) LARVAE
Authors: Marshall Gail A. , Amborski Robert L. , Culley Dudley D.
Published: August 2010

Skeletal deformities previously observed in Rana catesbeiana larvae reared in water containing <4 mg/liter calcium were suspected to be caused by calcium deficiencies. Initial studies utilizing the low calckum water showed that an increase of total calcium in the diet from 0.5 to 0.9% significantly (p< .001) reduced the frequency and severity of deformities.

Mortality rates of Rana catesbeiana larvae increased significantly (p< .001) at pH levels above 8.1. Newly hatched larvae maintained for three weeks in water buffered at either pH 7.2 or 8.3 experienced mortality rates of 10.0 and 96.7%, respectively. Larvae maintained at pH 7.2 for three weeks and then at pH 8.3 for four weeks experienced higher mortality rates than did a similar group of larvae maintained at pH 7.2 for seven weeks (23.3% and 3.6% respectively). Bacteriological analysis of surviving larvae maintained at pH 7.2 or 8.3 indicated greater numbers of potentially pathogenic bacteria in the carcass and gut of larvae at pH 8.3.
MATURATION OF PENAEID SRHIMP: LIPIDS IN THE MARINE FOOD WEB
Authors: Middleditch B. S. , Missler S. R. , Hines Harry B. , Chang E. S. , McVey J. P. , Brown A. , Lawrence A. L.
Published: August 2010

We have determined that certain lipids are required in the diets of penaeid shrimp to promote ovarian maturation. In an attempt to identify appropriate feedstock supplements which contain these lipids, we have examined several invertebrate species from two locations: West Bay, Galveston, and the Gulf of Mexico 50 km offshore from Galveston. At each location, with a few notable exceptions, the lipid profiles for the various species are very similar. This finding implies that many lipids pass through the food web unaltered and that the suitability of a particular invertebrate for inducing ovarian maturation may depend upon the diet of that invertebrate.
PRODUCTION OPTIMIZATION AND ECONOMIC ANALYSIS OF AN OYSTER (Crassostrea virginica) HATCHERY ON THE CHESAPEAKE BAY, MARYLAND, USA
Authors: Lipschultz Fredric , Krantz George E.
Published: August 2010

Production dynamics and economics of a large‐scale oyster (Crassostrea virginica) hatchery operated by the University of Maryland were investigated using a series of Linear Programming models. Development of models was based on a year of detailed operational data and biological phenomena peculiar to the low‐salinity (12–15 ppt) hatchery site.

The model successfully identified production bottlenecks. When both the model and hatchery operations were altered to alleviate a given resource constraint, the model predicted subsequent problem areas. Revisions of hatchery equipment‐mix and production methods were easily incorporated into the Linear Programming framework and the resultant effects evaluated.

Economic feasibility of the oyster hatchery as a commercial venture was estimated using actual building costs at a 12% interest rate, straight‐line depreciation, and optimized production estimates. Analyses were conducted for both the current hatchery and a hatchery with a modified equipment‐mix within the same building. When both hatcheries were coupled to a harvesting operation, they were capable of a sustained gross profit after the initial start‐up, but were only marginally successful in recovering from a crop failure or any level of revenue loss. The modified equipment‐mix design demonstrated potential for marked production increases by further refinement in arrangement and use of hatchery equipment.

When the model simulated the hatcheries operating solely as seed oyster facilities rather than as a component of a harvesting operation, both the current hatchery design and the redesigned hatchery demonstrated an ability to generate profit. However, this potential relies heavily on good growth conditions in the hatchery; salinity fluctuations or equipment failure could drastically reduce the hatchery output.
ECONOMIC ASPECTS OF POND CULTURE OF TOPMINNOWS (FAMILY POECILIIDAE) IN HAWAII AS AN ALTERNATIVE BAITFISH FOR SKIPJACK TUNA1
Authors: Shang Yung C. , Baldwin Wayne J.
Published: August 2010

The unit production cost of cultured topminnow (Poecilia vittata and P. mexicana) was less than the opportunity cost of captured Nehu (Stolephorus purpureus), the traditional live baitfish used for the skipjack tuna (Katsuwonus pelamis) fishing in Hawaii. The production cost of culture topminnow was estimated in the range of $3.20‐6.06 per kg, while the estimated opportunity cost of Nehu was about $22.00 per kg.
GENETIC STUDIES OF THE BLUE MUSSEL, Mytilus edulis, AND THEIR IMPLICATIONS FOR COMMERCIAL CULTURE
Authors: Newkirk G. F. , Freeman K. R. , Dickie L. M.
Published: August 2010

Genetic differences among natural populations of the blue mussel (Mytilus edulis) appear to have implications for commercial exploitation of the species. Growth and mortality patterns in transplanted versus resident wild stocks presented here verify that the genetic differences among populations involve the production parameters. Hatchery produced juveniles from various populations outplanted at different sites showed different mean growth rates depending on parent stock. These observations suggest there are adaptations to local conditions and underscore the need for careful selection by the mariculturist of both site and source of seed stock.