Stocking Programs Research Articles

Four Approaches to Commodity Market Stabilization: A Comparative Analysis

AbstractThe effects of four alternative price stabilization programs for soybeans are compared using a rational expectations model and simulation. For a given government expenditure, subsidized private storage is the most efficient way to stabilize market price. For a given deadweight loss, a program of direct payments is the most efficient stabilizer of the effective farm price; this program does not stabilize market price. All four programs, including a buffer stock program and one involving both direct payments and buffer stocks, tend to destabilize quasi‐rent. Programs that involve an initial build‐up of stocks increase producer benefits and hurt consumers.

Evidence of Introgressive Hybridization in the GenusStizostedion: Interspecific Transfer of Mitochondrial DNA between Sauger and Walleye

The mitochondrial genotypes of walleye (Stizostedion vitreum) and sauger (Stizostedion canadense) are readily differentiated, permitting an analysis of the incidence of hybridization between the taxa. We provide evidence that introgression of sauger into walleye has occurred: two female walleye collected from Lake Simcoe contained a mitochondrial genome identical to that of sauger. Not only were these two fish morphologically indistinguishable from typical walleye, they were homozygous for the diagnostic alleles characteristic of walleye at the Mdh-3 and Pgm-1 allozyme loci. Sauger have not been recorded in Lake Simcoe, but a few individuals may have been inadvertently introduced during stocking programs and introgressed with walleye due to a lack of conspecific mates.

DNA-Level Polymorphism as a Tool in Fisheries Science

Several methods for the visualization of genetic polymorphisms at the nucleic acid level have been developed. Such polymorphisms promise to be exceedingly numerous, and may form the basis for a number of scientific and practical applications in fisheries science. An expanded number of genetic markers should increase the statistical power of marker-based studies in population genetics, for example, improving the sensitivity of biological stock assessments and of studies assessing the impact of stocking programs upon natural populations. Utilization of such genomic markers could contribute to the rapid elaboration of piscine genomic maps and to development of markers for health- and production-related traits in fishes.

Effects of Climatic and Density-Dependent Factors on Year-Class Strength of Coregonus lavaretus in Lake Constance

The influences of density-dependent and density-independent factors on year-class strength (YCS) of Coregonus lavaretus in Lake Constance were studied by multiple linear regression analyses for the period from 1962 to 1982. Meteorological conditions that lead to early thermal stratification of the lake in April are of prime importance for YCS and account for 41% of the total YCS variance. Zooplankton concentration during spring has no significant influence on YCS. The extensive stocking program on the lake (50–200 million larvae stocked per year) significantly supports YCS, but this relationship becomes apparent only after the influence of meteorological conditions are removed from the data. Conspecifics of age-classes 1 and 2 have a negative influence on the age 0 year-class, but the nature of this intraspecific competition remains unknown. No stock–recruitment relationship could be detected in this study. The final model includes five independent variables and accounts for 84% of the total YCS variance.

Catchable Trout Fisheries: The Need for Assessment

Abstract State fisheries agencies were questioned regarding their catchable-size (>178 mm) salmonid stocking programs, specifically: (1) number, species, and propagation cost of catchables stocked; (2) total length of stream and area of impoundments stocked; (3) methods used to estimate angler effort and harvest of catchables; (4) extent to which these techniques have been employed in the past 10 years. In 1983, 43 states stocked in excess of 50 million catchable-size trout at a production cost of nearly $37 million. Rainbow trout (Salmo gairdneri) was the most popular species, predominating in 28 states and accounting for more than 77% of all catchable salmonids stocked. Brook trout (Salvelinus fontinalis) and brown trout (Salmo trutta) were the next most frequently stocked salmonids (11.0% and 10.1% of total, respectively). More than 54,000 km of streams and 550,000 ha of ponds, lakes, and reservoirs were planted with catchables in 1983. Most methods utilized by management agencies to assess use and har...

Rainbow trout (Salmo gairdneri) stocking and Contracaecum spp.

A stocking program with rainbow trout (Salmo gairdneri) at High Rock Lake, Manitoba failed due to infections with large numbers of Contracaecum spp. larvae. Nematode larvae in the intestinal tract, body cavity and musculature made the fish unmarketable. A combination of experimental infections of rainbow trout and pelicans (Pelecanus erythrorhynchos), observations on the behavior of fish-eating birds, and numbers of larval Contracaecum spp. in minnow species led to the following conclusions. The introduction of rainbow trout attracted large numbers of fish-eating birds, particularly pelicans. Concurrent predation by rainbow trout on fathead minnows (Pimephales promelas), five-spined sticklebacks (Culaea inconstans), and nine-spined sticklebacks (Pungitius pungitius), concentrated the parasites. The combined increase in densities of the introduced fish host and fish-eating birds, and the short life cycle of the parasite, increased the numbers of parasites in rainbow trout over a season and in the indigenous minnow species between years. Numbers of larvae in the indigenous minnow species declined when stocking of rainbow trout was stopped and use of the lake by fish-eating birds, particularly pelicans, returned to normal levels.

Evaluation of Supplemental Stocking of Largemouth Bass as a Management Tool in Small Impoundments

Largemouth bass (Micropterus salmoides) fingerlings (35-64 mm total length) were supplementally stocked into two small Oklahoma impoundments, Liberty Lake and Wiley Post Lake, in July 1980 at a density of 450/hectare to enhance year-class strength. Stocked fish constituted 76 and 72% of the 1980 year class in Liberty and Wiley Post lakes, respectively, for two growing seasons following stocking. Natural mortality at age 1 + appeared to drastically reduce the numbers of stocked fish. The stocked largemouth bass reached quality length (300 mm) toward the end of the third growing season and made up 3 and 17% of the quality-length fish in the 1983 electrofishing samples from Liberty and Wiley Post lakes, respectively. Creel data indicated that angler catches and harvest rates were unaffected by the stocking program.

Electrophoretic evaluation of a supplemental stocking programme for brown trout, Salmo trutta L.

Abstract. Over a 15-year period hatchery brown trout, Salmo trutta L., have been added 10 Lower Lough Erne, Northern Ireland to supplement declining native populations. Introductions have mainly comprised eyed ova and fingerlings, stocked into a number of rivers in the Erne drainage. Utilizing a natural genetic tag an electrophoretic assessment of the stocking programme was undertaken. The percentage hatchery genetic contribution in trout populations varied widely from river to river (19%-91%). Lough-caught brown trout (3+ and older) showed a substantial (21·5%) hatchery genetic component. Introgression of native-and hatchery stocks was evident. The resultant deleterious genetic consequences for the conservation of the unique Lough Erne brown trout gene pool arc discussed and alternative management strategies are proposed.

Creation of a Hybrid Striped Bass Fishery in the Escambia River, Florida

A fingerling stocking program with hybrid striped bass (Morone saxatilis x Morone chrysops) produced a significant fishery in the Escambia River and estuary. An estimated 8,507 hybrids were harvested from June 1981 through May 1982 with a catch rate of 0.46 fish per man-hour. Harvest and success rates declined during the summer and fall of 1982. This decline is attributed in part to emigration of hybrids into the bay and adjacent river systems during periods of high river discharge. Future harvest rates of the hybrid fishery may depend on seasonal fluctuations in river discharge.

Artificial hatching substrate: Effect on yolk absorption, mortality and growth during first feeding of sea trout ( Salmo trutta)

Groups of sea trout ( Salmo trutta) eggs were hatched in a Californian hatching system with and without an astro-turf artificial substrate, and were later transferred to separate feeding units. Alevins reared in astro-turf absorbed their yolk faster and more efficiently than alevins reared on a flat screen, an effect which is probably caused by high activity stress in the flat-screened system. Probably due to higher yolk reserves, the fry hatched without astro-turf grew faster than the fry reared with astro-turf during the first periods of feeding. Later this was reversed, giving the astro-turf-reared alevins the highest growth rate. The flat-screen-reared alevins/fry suffered higher mortalities during the experiment and the mortalities were clearly size dependent. These results have consequences both for intensive culture and stocking programmes since the traditional hatching systems both reduce growth and the chance of survival of the fry.

Liver pathology of yellow perch, Perca flavescens (Mitchill), infected with larvae of the nematode Raphidascaris acus (Bloch, 1779).

Larvae of the nematode Raphidascaris acus were found free or encapsulated in the liver of yellow perch. Blood vessels were distorted or destroyed during larval migrations and larvae were eventually encapsulated in a thick-walled whitish nodule. Successful walling-off of the parasite resulted in the formation of a collagenous nodule and a complete loss of the worm. No mortality of perch was associated with larval R. acus but the introduction of susceptible fishes into a lake harboring this parasite may be important in some stocking programs.

The Effects of Fin-Clipping, Floy-Tagging and Fin-Damage on the Survival and Growth of Brown Trout (Salmo trutta L) Stocked in Irish Lakes

The results of a series of experimental stocking programmes designed to assess the effects of fin-clipping, fin-damage and floy tags on the survival and growth of brown trout (Salmo trutta L.) are presented. Data indicate that even a single fin clip can seriously reduce survival and also retard the growth of fish. Trout released with extensive fin-damage also exhibited poorer survival and growth patterns than their unmarked counterparts. The growth and survival of trout (≥ 18 cm) does not appear to have been altered by floy-tagging.

An Efficient Hatchery Strain of Rainbow Trout for Stocking Oregon Streams

Increased costs of raising and stocking trout threaten many catchable trout programs, because benefit-to-cost ratios are declining and budgetary constraints further limit the number of fish that can be stocked. Varieties of cultured rainbow trout (Salmo gairdneri) differ in efficacy in a hatchery situation, but their comparative performance in the wild is little known. A case history is presented of creel survey and migration studies conducted in Mill Creek, a popular angling stream in the Willamette Valley, Oregon, to identify cost- and performance-effective trout strains for catchable trout stocking programs. One variety, Cape Cod, comparatively recent to the state, yielded significantly better results (higher catches and less out-migration) than the other two varieties, Roaring River and Oak Springs, and a change in management policy for trout stocking was implemented.

Socioeconomic Value of the Trout Fishery in Lake Taneycomo, Missouri

Abstract Lake Taneycomo, a 700-hectare hydroelectric impoundment in southwestern Missouri, supports an excellent put-grow-and-take fishery for rainbow trout Salmo gairdneri. When the fishery became threatened by releases of deoxygenated water from an upstream reservoir, it became important to determine its value. We used three methods for estimating the value of the fishery: Replacement cost of fish; travel cost; and income multiplier. Information for the latter two methods was based on 500 angler interviews. Replacement cost of the rainbow trout would be $0.5 million. The travel-cost method provided an estimate of $2.9 million for the value of the fishery to anglers (consumers' surplus). The income-multiplier method provided an estimate of $9.9 million for the net economic benefit to the local economy, or about 7% of all economic activity in the area. The benefit: Cost ratio of the rainbow trout stocking program at Lake Taneycomo was 22:1 for the local economy.

Formulation of products from soybean oil

AbstractHigh quality shortenings and margarines may be produced using soybean oil as the only fat source or using soybean oil as the primary fat source with the addition of a small amount of hydrogenated cottonseed or palm oil to provide crystal stability. These shortenings and margarines are manufactured by direct hydrogenation or by blending hydrogenated and/or unhydrogenated base stocks. The properties of soybean oil preclude the need for processes other than hydrogenation and blending to produce most margarine and shortening products. It is possible to design an integrated base stock program in which a limited number of base stocks may be used jointly in margarine and shortening formulations. This type of base stock program results in fewer hydrogenation department heels and simplifies scheduling of the hydrogenation department as well as scheduling of overall operations. Solid fat index (SFI) is the analysis used for final product consistency control. While base stocks are blended to meet a final SFI requirement, this analysis is too time‐consuming to be used in hydrogenation control and individual hydrogenation batches are controlled using refractometer number and congeal points. Finished product characteristics are a result of decisions that must be made regarding characteristics such as plastic range and AOM stability, which are incompatible.

Effect of monensin or ruminal fermentation, forage intake and weight gains of wheat pasture stocker cattle.

The effects of monensin or ruminal fermentation, forage intake and weight gains of stocker cattle grazed on wheat pasture were studied. In the first of two ruminal fermentation studies, ruminal fluid pH was increased and total volatile fatty acid (VFA) concentrations at 4 (p less than .01) and 24 hr postfeeding were decreased in steers fed 200 mg monensin/day. However, no such changes in ruminal fluid pH and total VFA concentrations in monensin-fed steers were observed in trial 2. The ruminal fluid acetic to propionic acid ratio of steers that received monensin was decreased (P less than 0.5) by about 40 and 20% of trials 1 and 2, respectively. Results of two forage intake trials, in which steers received 0 or 200 mg monensin daily, were not consistent, precluding conclusions about the effect of monensin, per se, on stocking rate adjustments when the additive is used in wheat pasture stocker programs. In each of two growth trials, conducted over 2 years, about 125 heifers per year were divided into three groups: one group grazed wheat pasture and received no supplement, and the other two grazed wheat pasture and were fed a pelleted supplement that contained 0 or 100 mg monesin. Daily gains of heifers fed monensin were .08 kg greater (p less than .01) than those fed supplement without monensin. The data indicate that monesin does have potential for use in wheat pasture stocker programs.

Buffer stocks are better stabilizers than quotas

Michael Pelcovits (1979, p. 307) recently showed that with an unstable foreign excess supply curve, either a fixed quota or a buffer stock program with a fixed tariff can be used to stabilize domestic price at a given level, and both policies ‘will have the same effect on social welfare [so…t]he choice between [the two…] must then be made on the basis of administrative cost and feasibility’. However, he reached his conclusion by ranking the two policies on the basis of domestic welfare, and in this note we demonstrate with his same model that on the basis of foreign welfare the buffer stock is better than the quota. Thus, world welfre is higher under the buffer stock than under the quota.

Effects of Alternative Specifications on the Policy Implications of a Model: an Illustration

Most agricultural economists involved in quantitative policy analysis would probably agree that the formulation and specification of the mathematical models they use has an important impact on the results of their policy analysis. Nevertheless it appears that agricultural economists have been less successful than economists studying macro-economic relationships, in evaluating models and subjecting them to the rigorous tests that reveal a model's inherent biases and internal dynamics. [3, 8,9, 131. The purpose of this note is to show how changing the specification of one equation in a simple econometric model can have a dramatic impact on the policy implications of the analysis.' I' The Model Zwart and Meilke [20,21] recently reported on research undertaken to evaluate the effects of alternative buffer stock proposals on the Canadian and Rest of World (ROW) wheat economies. The general conclusion of that research was that a wheat buffer stock program was not likely to increase the mean level of price, consumption, or industry income in the world wheat economy, but it could add to the stability of the industry. With a world buffer stock the within-year standard deviation of world price could be reduced by 21.4 percent and ROW consumer surplus by 8.9 percent.* Nothing in the following analysis changes the general conclusions of the study referred to above, nevertheless the careful reader of the previous work may have noticed the following: (1) the average price over the simulation period, with no stock, was $217.30 per ton with a standard deviation of $12.60 per ton; (2) policy 6 which was a world buffer stock employing a flexible price rule coupled with an inflexible quantity rule resulted in a mean price of $217.00 per ton and a standard deviation of $9.90; and, (3) the reduction in the standard deviation between the no

The eventual failure of price fixing schemes

This essay examines the feasibility of a government buffer stock program which attempts to fix a relative price over time. In the model, m risk averse agents with random endowments of two commodities maximize expected utility over an infinite horizon. It is shown that a price fixing scheme will fail with probability 1, regardless of the price set by the government and regardless of the initial level of buffer stocks. The proof of this proposition turns on some well-known properties of random walks.

Clonal Multiplication of Carnation by Micropropagation1

Abstract Clonal multiplication of carnation (Dianthus caryophyllus L.) was accomplished in three stages: 1) shoot tip culture initiation stage, 2) shoot multiplication stage, and 3) rooting stage. The culture medium for the initiation stage was examined by comparing various inorganic salt mixtures, vitamin mixtures, carbohydrates, growth regulators, agars, pH’s, and additional supplements for their effect on growth and development of multiple shoots from shoot tips. When shoot tips (ca. 1 mm high) were grown on a modified Murashige and Skoog medium with 10 µM kinetin and 1 µM NAA, apical dominance was counteracted and morphologically normal shoots proliferated rapidly. Transferring these cultures after 4 wk to 100 ml flasks (one per flask) with 50 ml of same medium without agar and supplements, and with the kinetin concentration reduced to 2.5 µM, resulted in an average per original shoot tip of 28 shoots over 2 cm in height being produced in another 3 weeks. These shoots were rooted in BR-8 blocks or Jiffy-7 peat pellets under intermittent mist. Plantlets rooted in these supports were transferred easily to greenhouse conditions. Incorporation of carnation micropropagation into a pathogen-free propagative stock program should not be difficult, and might prove beneficial even if large scale use is limited by economic considerations.