This dissertation consists of analyses of a series of common pool resource experiments that I designed and conducted in three regions of Colombia with individuals who face similar dilemmas in their everyday lives as those faced in the experiment. The objectives are to develop an empirical characterization of how individual behavior deviates from purely self-interested Nash behavior, and to further our understanding of the effects of alternative institutions to promote more conservative choices in common pool experiments. The results of this dissertation are organized in three essays. The first essay, What Motivates Common Pool Resource Users?, develops and tests several models of pure Nash strategies of individuals who extract from a common pool resource when they are motivated by combinations of self-interest, altruism, reciprocity, inequity aversion and conformity. The experimental data suggest that a model that balances self-interest with a strong preference for conformity best describes average strategies. The data are inconsistent with a model of pure self-interest, as well as models that combine self-interest with individual preferences for altruism, reciprocity and inequity aversion. The second essay, Communication and Regulation to Conserve Common Pool Resources, tests for complementarities between formal regulations imposed on a community to conserve a local natural resource and non-binding verbal agreements to do the same. The experiments suggest that formal regulations and informal communication are complementary in some instances, but this result is not robust across regions or regulations. Therefore, the hypothesis of a complementary relationship of formal and informal control of local natural resources cannot be supported in general; instead the effects are likely to be community-specific. The third and final essay, Within and Between Group Variation in Individual Strategies in Common Pools, analyzes the relative effects of groups and individuals within groups in explaining variation in individual harvest decisions for particular institutions, and examines how these sources of variation may vary across institutions. Communication serves to effectively coordinate individual strategies within groups, but these coordinated strategies vary considerably among groups. In contrast, regulatory schemes (as well as unregulated open access) produce significant variation in the individual strategies within groups, but these strategies are roughly replicated across groups so that there is little between-group variation.

The São Francisco River (SFR), a floodplain river southeast of the Amazon River, provides commercial and recreational fishing for thousands of people, but fisheries have collapsed in the last decade. During 32-months, I radio-tracked 37 curimbatas (Prochilodus argenteus , Characidae, 0.8–2.9 kg) and 24 surubims (Pseudoplatystoma corruscans, Pimelodidae, 9.5–29.0 kg), two important commercial and recreational fishes. I did the study to characterize their migratory style and to determine if the cool hypolimnetic discharge from an upstream dam (Três Marias Reservoir, TMR) would block their upriver migration. I also made a conceptual model of the biological; river, dam, reservoir, and economic factors for a supplemental water release (SWR) to enhance SFR fisheries using a release from TMR. Migratory style of both species was dualistic with resident and migratory individuals. Home range was 1–127 km for curimbatá and 1–210 km for surubim. The most important spawning area for curimbatas was the SFR mainstem at its juncture with the Abaeté River mouth, and for surubims, the most important spawning area was the mainstem at Pirapora Rapids. Pre-spawning adults of both species staged at or near the spawning grounds. Some curimbatas and surubims homed to pre-spawning staging areas and to spawning areas. Some curimbatás also homed to non-spawning areas. The movements and thermal fluctuations experienced by both fishes showed they are eurythermal with a broad short-term temperature variation tolerance. Also, water discharged from dams that is <5°C cooler than ambient river water will not disrupt their migrations. The best date for a SRW is when there is a natural flood, which triggers spawning. The SWR will intensify the natural flood, cover a greater floodplain area, and increase survival of early life stages of fish. The TMR frequently impounded enough water for SWR only in the second half of the fish spawning season (January–March). Lost revenue at TMR depended on release volume and ranged from US$ 0.493 million to US$ 3.452 million for the actual power rate. However, SWR could increase commercial fisheries income an estimated US$ 4.468 million. Planned construction of 16 dams in the mainstem and tributaries downstream from TMD will greatly affect curimbatá and surubim migrations and spawning habitat, extirpate populations, and eventually reduce their abundance.

The composition and distribution of freshwater fish in 691 Massachusetts streams (1,430 samples statewide) surveyed during 1969-1987 were documented. White sucker (Catostomus commersoni) was the most ubiquitous species, while blacknose dace (Rhinichthys atratulus) and brook trout (Salvelinus fontinalis) were the most abundantly represented. Brown trout (Salmo trutta) appear well-distributed in contrast to historical records. A classification system for wadeable-sized streams in Massachusetts was developed using exploratory, multivariate statistics to identify repeated patterns of stream structure and function, based on the relationship between measured habitat variables and stream fish species assemblages, with particular emphasis on reproducing trout populations. The ordination technique of detrended correspondence analysis provided a portrayal of stream fish species relative to their distributional pattern along environmental gradients statewide. This analysis, in correspondence with established physiographic regions and documented limits of fish species distribution, facilitated the delineation of three fish faunal regions in Massachusetts, encompassing the Berkshire-Valley, Central-Upland, and Coastal-Lowland areas of the state. Cluster analysis of stream gradient and summer water temperature measures, followed by discriminant analysis, led to the development of a six-class thermal-gradient model which effectively classified 79 percent of a test-data set, on the basis of discrimination between optimal (reproducing) trout and non-trout streams. Stratified by fish faunal region, analysis of fish-group structure within predicted stream habitat classes were investigated, relative to determinants of stream habitat degradation. Fish species assemblages in Massachusetts' smaller, wadeable streams differ along an environmental gradient from the western Berkshire highlands to the eastern Coastal seaboard. Within the limits of fish species biogeography, a similar gradient is operative within any given drainage system as well. However, this gradient is not necessarily continuous, but varies primarily in response to abiotic factors of the environment, which then serve to regulate fish species occurrence. This system for classifying streams along an environmental continuum of chemico-physical conditions, serves as an initial macrohabitat "templet" upon which to base further evaluation of environmental impacts on stream ecosystem structure and function. It will also be used to manage the Commonwealth's lotic environments by ecological resource category, leading to implementation of a statewide wild trout management program.

Bibliography: pages 95-109. / The bioenergetics and growth of white steenbras, Lithognathus lithognathus, under culture conditions were determined to assess its suitability for mariculture. Fish were captured by seine netting, from nearby estuaries and transported to the laboratory where they were successfully kept for the duration of the experimental period. The fish were initially fed on white mussels and then weaned onto a diet of commercial trout pellets. The bioenergetics of L.lithognathus was examined using a large, simple closed system respirometer in which nitrogen excretion and oxygen consumption were measured simultaneously. This system permitted the use of groups of fish for experiment which simulated aquaculture conditions. The effects of fish size, ration size and temperature on faecal and nonfaecal excretion, and on oxygen consumption of L.lithognathus were examined.

In the aquaculture of fish and shrimps, diets generally contain high levels of fish meal. Fish meal is a nutrient rich feed that contains essential amino acids and fatty acids, which are required to maintain optimum growth and health of an animal. It is traditionally used in aquaculture to promote feed efficiency, nutrient uptake and feed intake due to its high palatability and digestibility. Overexploitation of fisheries resources and the high growth rate of aquaculture industry, however, continues to put pressure on the supply of fish meal, thus increasing the demand and price of this sought-after product. The use of alternative ingredients to fish meal, therefore, remains a high priority for aquaculture nutrition. Hence, the aim of this was to investigate the physiological and developmental effects on juvenile spotted grunter, Pomadasys commersonnii, after supplementing fish meal with different feed additives for 12 weeks. One of the additives was then selected for further feeding at graded levels (increasing levels) for 8 weeks to ascertain whether fish meal could be replaced by higher amounts of the feed additive without negative consequences to the cultured spotted grunter.

The Utah chub is one of the most important non-game fish in Utah. It has a wide range, and occurs in every drainage in Utah. The Utah chub is not important economically as food fish nor is it of much value commercially. The sportsmen think of this species as trash and do not consider catching or consuming the. However, the Utah chub may be caught on hook and like more readily than many game species. The Utah chub in Scofield Reservoir have been caught by trolling, bait fishing and fly casting and furnish considerable sport when caught with a light tackle. Their real importance becomes evident when a large population of Utah chub exist in waters where game fish species are desired. With their high reproductive potential, the Utah chub may become the dominant species and cause trout populations to decrease. This competition for food and space has been evident in many areas. Hazzard (1935) stated that Utah chub and trout compete with trout for food in Fish Lake, Utah, and Sigler (1948) also found that Utah chub compete with trout for food.

With the goal of obtaining the maximum utilization of areas now open to public hunting in mind, a study was conducted at the Bear River Migratory Bird Refuge during the 1960 and 1961 waterfowl hunting seasons. The study had the following main objectives: 1) determine the level of utilization of the refuge by water fowl hunters including determining the factors which affect the utilization of various areas of the refuge, determining the factors and their influence on the kill composition in the various areas and the entire refuge, and obtaining quantitative and qualitative information on hunter population and the use it may have in interpreting behavior patterns of hunters; and 2) determine methods by which utilization of the refuge can be increased to accommodate the greatest number of hunters and still provide good hunting.

This project investigated several aspects of the autecology of the brackish water clam Rangia cuneata in the James River, Virginia. The study, conducted from August, 1970, through March, 1972, was primarily concerned with substrate and salinity effects on growth and condition index of R. cuneata. The studies were conducted in sand and mud substrates in four different salinity regimes. Monthly samples of 15 clams were collected at each of the eight stations for condition index determinations. Condition index was shown to vary seasonally, with a low point in early spring and a maximum in early fall. Values were higher in sand bottoms than in mud and decreased in both substrates in fresher water. Clams from sand bottoms showed a pronounced fall peak which was not evident at most mud stations. A field experiment to evaluate the relative importance of water associated and sediment-associated factors in determining condition index showed that some factor associated with the water pumped by the clams was most important. The hypothesis is presented that this factor may be related to the large difference in suspended solids taken in by clams in sand and mud bottoms. Growth studies were based on marked individuals planted at all eight stations and recovered after one year. Growth was measured in terms of shell length and live weight increases. In terms of both criteria, growth was greatest at the three downriver sand stations. The lowest salinity sand station showed considerably less growth, but exceeded the growth at all mud stations. Clams at the latter showed similar small increases in both length and weight. The above patterns of condition index and growth are discussed in relation to salinity structure and suspended solids in the environment and to osmotic stress and spawning activity of the clams. An explanation is offered for the large size and relatively high condition index of clams near their limit of penetration into fresh water. The potential commercial value and annual harvest of R. cuneata in the lower James River is estimated. This dissertation is from the Joint Program Degree from the College of William & Mary and University of Virginia and awarded by the University of Virginia.

Aquaculture methods are limited for white crappie (Pomoxis annularis), reducing production potential. Therefore, reproduction methods, including induced spawning, sperm cryopreservation and out-of-season spawning, were developed in tank systems. A two week acclimation period (15°C; 3-5 ppt salinity) was necessary to reduce disease-related mortality. Afterwards, four spawning induction hormones and a control were examined to induce spawning. Luteinizing hormone releasing hormone analogue and salmonid gonadotropin releasing hormone analogue performed the best in terms of spawning success and %ertilization. Sperm cryopreservation was effective using Hanks or Ca2+ree Hanks balanced salt solutions with 10%-methanol or 5%-dimethyl-sulfoxide as a cryoprotectant, frozen at 40°C/min. Out-of-season spawning experiments manipulated photoperiod and temperature over 3-wk (9% spawning success; 11% fertilization) and 6-wk (16% spawning success; 55% fertilization) seasonal shifts. Post-experiment maturation data indicate that females were in an intermediate development stage. These experiments demonstrate the potential of advanced spawning techniques to improve annual production of white crappie.

No description available.