Channel Catfish are broadly distributed in the U.S. and are important commercially and recreationally in many rivers, lakes, reservoirs, and streams. Since they are a popular sportfish, many state-owned lakes are stocked with a variety of sizes to enhance population sizes and provide angling opportunities. The goals of this study were to determine the contributions of stocked fish, determine the fish size at stocking, and to assess the contribution of yearling and catchable sizes to the stocked percentage. Fish samples were obtained from three hatcheries and six lakes within different ecoregions across Arkansas to assess whether chemical signatures were different among locations. Sectioned pectoral spines were analyzed for Sr:Ca and Ba:Ca using laser ablation-ICPMS to determine whether location-specific Sr:Ca and Ba:Ca signatures were reflected in pectoral spine samples, and to assess the accuracy with which fish could be assigned to their collection location using spine Sr:Ca and Ba:Ca. Fin spine core Sr:Ca and Ba:Ca data were also used to identify stocked fish and determine size at stocking for hatchery-origin fish sampled from each of the six lakes. Spine microchemistry represents a non-lethal approach to identify stocked catfish and infer size at stocking, which will better inform allocation of hatchery-produced fish. Differences in pectoral spine Sr:Ca edge signatures among locations were detected, which were primarily driven by differences in geology among ecoregions. Assignment accuracy of fish to collection location using Random Forest Modeling was 88% or greater for all but one of the study lakes. This allowed for application of the random forest model on pectoral spine core Sr:Ca and Ba:Ca to assign individuals sampled from the lakes as hatchery or wild origin. Among all the Channel Catfish sampled from the six lakes, 45% were identified as hatchery origin and 46% of those were stocked as catchable size fish. Contributions of stocked fish varied among study lakes from 0% to 100%. This was the first study to demonstrate that pectoral spine microchemistry can be used for assessing both stocking contribution and inferring fish size at stocking. Overall, this study will aid in the allocation of hatchery-reared catfish by management biologists, and could lead to more projects focused on exploring stocking contribution by microchemistry, such as assessment of how habitat enhancement may influence the contribution of natural reproduction to catfish populations.

A stochastic, compartmental Model for Adaptive Livestock Management (MALM) was developed for cow-calf enterprise for Rolling Plains of Texas from an existing model, Simple Ecological Sustainability Simulator (SESS). The model simulates forage and animal production. It runs on a monthly time step. Two stocking strategies, flexible and fixed, were evaluated at seven stocking levels for effects on forage and animal production, range condition, and net ranch income. Evaluation data were obtained from published and unpublished data from Texas A&M Agricultural Experimental Station at Vernon for Throckmorton. The model adequately simulated forage and animal production. Light fixed stocking rates and flexible stocking strategies resulted in cows of median body condition score (BCS) 5, compared to low BCS of 4 under moderate fixed stocking rate, and BCS of 3 under heavy fixed stocking. BCS declined from autumn to early spring and peaked in summer. Cows under light fixed stocking rates and under flexible stocking were heavier (460 kg) compared to those under heavy fixed stocking (439 kg). Replacement rates were lower under light stocking (22 %), compared to flexible (37 %) and heavy stocking (56 %). Calf crops were all above the reported 90 % expected for bred heifers because of the replacement policy. Flexible stocking strategy resulted in higher net income ($19.62 ha-1), compared to fixed light ($5.93 ha-1) or fixed heavy ($-17.35 ha-1) stocking strategies. Coefficient of variation (CV) in net income was highest under heavy stocking (90%) compared to light stocking (60%) and flexible stocking (50%). Maximum net income was obtained between 0.05 AUM·ha-1 and 0.13 AUM·ha-1 when fixed stocking strategy was used but when flexible stocking strategy was used maximum net income was obtained between 0.1 AUM·ha-1 and 0.17 AUM·ha-1. Range condition rapidly declined under fixed heavy stocking, increased under fixed and light flexible stocking, and remained constant under moderate flexible stocking. Heavy fixed stocking decreased range condition rapidly over a 20-year period. MALM was an effective tool to demonstrate effects of different management strategies. The model can function as a strategic or a tactical decision aid. It is concluded that there is potential for this model to assist managers in improving the sustainability of agriculture.

A stochastic, compartmental Model for Adaptive Livestock Management (MALM) was developed for cow-calf enterprise for Rolling Plains of Texas from an existing model, Simple Ecological Sustainability Simulator (SESS). The model simulates forage and animal production. It runs on a monthly time step. Two stocking strategies, flexible and fixed, were evaluated at seven stocking levels for effects on forage and animal production, range condition, and net ranch income. Evaluation data were obtained from published and unpublished data from Texas A&M Agricultural Experimental Station at Vernon for Throckmorton. The model adequately simulated forage and animal production. Light fixed stocking rates and flexible stocking strategies resulted in cows of median body condition score (BCS) 5, compared to low BCS of 4 under moderate fixed stocking rate, and BCS of 3 under heavy fixed stocking. BCS declined from autumn to early spring and peaked in summer. Cows under light fixed stocking rates and under flexible stocking were heavier (460 kg) compared to those under heavy fixed stocking (439 kg). Replacement rates were lower under light stocking (22 %), compared to flexible (37 %) and heavy stocking (56 %). Calf crops were all above the reported 90 % expected for bred heifers because of the replacement policy. Flexible stocking strategy resulted in higher net income ($19.62 ha-1), compared to fixed light ($5.93 ha-1) or fixed heavy ($-17.35 ha-1) stocking strategies. Coefficient of variation (CV) in net income was highest under heavy stocking (90%) compared to light stocking (60%) and flexible stocking (50%). Maximum net income was obtained between 0.05 AUM·ha-1 and 0.13 AUM·ha-1 when fixed stocking strategy was used but when flexible stocking strategy was used maximum net income was obtained between 0.1 AUM·ha-1 and 0.17 AUM·ha-1. Range condition rapidly declined under fixed heavy stocking, increased under fixed and light flexible stocking, and remained constant under moderate flexible stocking. Heavy fixed stocking decreased range condition rapidly over a 20-year period. MALM was an effective tool to demonstrate effects of different management strategies. The model can function as a strategic or a tactical decision aid. It is concluded that there is potential for this model to assist managers in improving the sustainability of agriculture.

No description available.

A escolha do espaçamento de plantio, para uma determinada espécie ou clone, em silvicultura é de alta relevância por condicionar a quantidade de recursos naturais disponíveis ao crescimento de cada árvore. Isto influencia as taxas de crescimento e sobrevivência das plantas e a produtividade de madeira por hectare, afetando as práticas de manejo e colheita e, conseqüentemente, os custos de produção florestal. Adicionalmente, há a necessidade de se definir o arranjo de plantio, ou retangularidade (razão entre as distâncias entrelinhas e entreplantas), sendo que aqueles com maior distância entrelinhas possuem maior apelo operacional por reduzirem os custos de preparo de solo ou da colheita da madeira. No entanto, teoricamente, o aumento da retangularidade deve diminuir a produtividade e uniformidade das florestas por reduzir a interceptação de luz e acelerar a estratificação das árvores, além de aumentar os riscos de matocompetição e danos causados por ventos. Assim, o presente trabalho buscou avaliar os efeitos de diferentes espaçamentos e arranjos de plantio na produtividade e uniformidade de dois clones de Eucalyptus selecionados para a região nordeste do Estado de São Paulo. O ensaio foi instalado em outubro de 1998, no município de Altinópolis-SP e consistiu de um fatorial completo 2 x 3 x 3, com 4 repetições, com dois materiais genéticos (clones de E.grandis x urophylla C041 e C219), três espaçamentos (6,0, 10,5 e 15,0 m² planta-1) e três arranjos, com distâncias entrelinhas de 3,0 m (3,00 x 2,00, 3,00 x 3,50 e 3,00 x 5,00), 6,0 (6,00 x 1,00, 6,00 x 1,75 e 6,00 x 2,50 ) e 9,0 metros (9,00 x 0.67, 9,00 x 1,17 e 9,00 x 1,67). Cada parcela teve uma área total de 900 m², com número de árvores e áreas úteis variáveis de 12 a 78 plantas, e de 180 a 468 m², totalizando 6,48 ha de ensaio. As avaliações dendrométricas foram realizadas aos 1,0, 1,5, 3,0, 4,0, 5,0 e 6,0 anos, e a biomassa da parte aérea (folhas, galhos, casca e lenho) foi avaliada ao final da rotação. Aos 6 anos, o clone C041 foi 11% mais produtivo em volume e 5% mais produtivo em biomassa de lenho do que o clone C219, com incrementos médios anuais (IMA) de 33,8 e 30,5 m³ ha-1 ano-1, respectivamente. Esta menor produtividade do C219 deveu-se a sua significativa maior susceptibilidade à quebra pelo vento, notadamente no arranjo de 9 metros. Para ambos os clones, verificou-se maior produção, em volume e biomassa de lenho no espaçamento de 6,0 m², com valores médios de 212 m3 ha-1 e 92 Mg ha-1, com reduções de 10% e 18% na produção para os espaçamentos de 10,5 e 15,0 m2 planta-1. Houve redução da produtividade com o aumento das distâncias entrelinhas, e o arranjo de 3 metros, com 34.0 m3 ha-1 ano-1 e 14.6 Mg ha-1 ano-1, foi 16% superior ao arranjo de 9 metros. Obteve-se um modelo de predição da produtividade, por clone, em função do espaçamento e do arranjo do plantio. Finalmente, observou-se a redução da uniformidade entre árvores clonais com a idade, com a redução do espaçamento e com o aumento da retangularidade. / Defining initial spacing for tree species, or clones, is relevant in silviculture because determines the amount of natural resources available for each tree growth. This influences tree growth rates and survival, and the final wood production, which affects the forest management and harvesting practices and, consequently, the forest production cost. Besides spacing, it is also necessary to define the plantation layout, or rectangularity (between-row to between-plants ratio), and the ones with larger betweenrow distance tend to be select by operational areas due to their low soil preparation or harvest costs. However, theoretically, the increase in rectangularity should reduce productivity and forest uniformity due to the reduction in light interception and the speed up of forest stratification, and can also increase weed competition and wind damage risks. This study was carried out to evaluate the spacing and layout effects on the productivity and uniformity of two Eucalyptus clones in the northeastern of Sao Paulo State. A complete 2 x 3 x 3 factorial design, with four repetitions, was installed in October 1998 in Altinopolis, with 2 clones (C041 and C219), 3 spacings (6,0, 10,5 and 15,0 m² tree-1) and 3 layouts with between-row distances of 3,0 m (3,00 x 2,00, 3,00 x 3,50 and 3,00 x 5,00), 6,0 m (6,00 x 1,00, 6,00 x 1,75 and 6,00 x 2,50 ) and 9,0 m (9,00 x 0.67, 9,00 x 1,17 and 9,00 x 1,67). Each plot had a total area of 900 m², with measured trees and areas ranging from 12 to 78, and 180 to 468 m², totalizing 6,48 ha. DBH and height measurements were done at 1.0, 1.5, 3.0, 4.0, 5.0 and 6.0 years-old, and aboveground biomass (leaves, branches, bark and stem) quantification at the end of the rotation. At 6 years-old, clone C041 was 11% more productive in volume and 5% more productive in stem biomass than clone C219, with mean anual increments (MAI) of 33.8 and 30.5 m³ ha-1 yr-1, respectively. Clone C219 was less productive due to its higher susceptibility to wind damage, mainly at 9 m layouts. For both clones, the 6,0 m² tree-1 spacing showed the larger production, 212 m3 ha-1 and 92 Mg ha-1, with a drop of 10% and 18% for the 10,5 and 15,0 m2 tree-1 spacing. Forest yield reduced with the increase in between-row spacing, and the 3 m layout, with 34.0 m3 ha-1 yr-1 and 14.6 Mg ha-1 yr-1, was 16% superior to the 9 m one. Yield prediction regression, per clone, was obtained as a function of spacing and layout. A reduction in forest uniformity among trees increased with increasing age, lower spacing and higher rectangularity.

A escolha do espaçamento de plantio, para uma determinada espécie ou clone, em silvicultura é de alta relevância por condicionar a quantidade de recursos naturais disponíveis ao crescimento de cada árvore. Isto influencia as taxas de crescimento e sobrevivência das plantas e a produtividade de madeira por hectare, afetando as práticas de manejo e colheita e, conseqüentemente, os custos de produção florestal. Adicionalmente, há a necessidade de se definir o arranjo de plantio, ou retangularidade (razão entre as distâncias entrelinhas e entreplantas), sendo que aqueles com maior distância entrelinhas possuem maior apelo operacional por reduzirem os custos de preparo de solo ou da colheita da madeira. No entanto, teoricamente, o aumento da retangularidade deve diminuir a produtividade e uniformidade das florestas por reduzir a interceptação de luz e acelerar a estratificação das árvores, além de aumentar os riscos de matocompetição e danos causados por ventos. Assim, o presente trabalho buscou avaliar os efeitos de diferentes espaçamentos e arranjos de plantio na produtividade e uniformidade de dois clones de Eucalyptus selecionados para a região nordeste do Estado de São Paulo. O ensaio foi instalado em outubro de 1998, no município de Altinópolis-SP e consistiu de um fatorial completo 2 x 3 x 3, com 4 repetições, com dois materiais genéticos (clones de E.grandis x urophylla C041 e C219), três espaçamentos (6,0, 10,5 e 15,0 m² planta-1) e três arranjos, com distâncias entrelinhas de 3,0 m (3,00 x 2,00, 3,00 x 3,50 e 3,00 x 5,00), 6,0 (6,00 x 1,00, 6,00 x 1,75 e 6,00 x 2,50 ) e 9,0 metros (9,00 x 0.67, 9,00 x 1,17 e 9,00 x 1,67). Cada parcela teve uma área total de 900 m², com número de árvores e áreas úteis variáveis de 12 a 78 plantas, e de 180 a 468 m², totalizando 6,48 ha de ensaio. As avaliações dendrométricas foram realizadas aos 1,0, 1,5, 3,0, 4,0, 5,0 e 6,0 anos, e a biomassa da parte aérea (folhas, galhos, casca e lenho) foi avaliada ao final da rotação. Aos 6 anos, o clone C041 foi 11% mais produtivo em volume e 5% mais produtivo em biomassa de lenho do que o clone C219, com incrementos médios anuais (IMA) de 33,8 e 30,5 m³ ha-1 ano-1, respectivamente. Esta menor produtividade do C219 deveu-se a sua significativa maior susceptibilidade à quebra pelo vento, notadamente no arranjo de 9 metros. Para ambos os clones, verificou-se maior produção, em volume e biomassa de lenho no espaçamento de 6,0 m², com valores médios de 212 m3 ha-1 e 92 Mg ha-1, com reduções de 10% e 18% na produção para os espaçamentos de 10,5 e 15,0 m2 planta-1. Houve redução da produtividade com o aumento das distâncias entrelinhas, e o arranjo de 3 metros, com 34.0 m3 ha-1 ano-1 e 14.6 Mg ha-1 ano-1, foi 16% superior ao arranjo de 9 metros. Obteve-se um modelo de predição da produtividade, por clone, em função do espaçamento e do arranjo do plantio. Finalmente, observou-se a redução da uniformidade entre árvores clonais com a idade, com a redução do espaçamento e com o aumento da retangularidade. / Defining initial spacing for tree species, or clones, is relevant in silviculture because determines the amount of natural resources available for each tree growth. This influences tree growth rates and survival, and the final wood production, which affects the forest management and harvesting practices and, consequently, the forest production cost. Besides spacing, it is also necessary to define the plantation layout, or rectangularity (between-row to between-plants ratio), and the ones with larger betweenrow distance tend to be select by operational areas due to their low soil preparation or harvest costs. However, theoretically, the increase in rectangularity should reduce productivity and forest uniformity due to the reduction in light interception and the speed up of forest stratification, and can also increase weed competition and wind damage risks. This study was carried out to evaluate the spacing and layout effects on the productivity and uniformity of two Eucalyptus clones in the northeastern of Sao Paulo State. A complete 2 x 3 x 3 factorial design, with four repetitions, was installed in October 1998 in Altinopolis, with 2 clones (C041 and C219), 3 spacings (6,0, 10,5 and 15,0 m² tree-1) and 3 layouts with between-row distances of 3,0 m (3,00 x 2,00, 3,00 x 3,50 and 3,00 x 5,00), 6,0 m (6,00 x 1,00, 6,00 x 1,75 and 6,00 x 2,50 ) and 9,0 m (9,00 x 0.67, 9,00 x 1,17 and 9,00 x 1,67). Each plot had a total area of 900 m², with measured trees and areas ranging from 12 to 78, and 180 to 468 m², totalizing 6,48 ha. DBH and height measurements were done at 1.0, 1.5, 3.0, 4.0, 5.0 and 6.0 years-old, and aboveground biomass (leaves, branches, bark and stem) quantification at the end of the rotation. At 6 years-old, clone C041 was 11% more productive in volume and 5% more productive in stem biomass than clone C219, with mean anual increments (MAI) of 33.8 and 30.5 m³ ha-1 yr-1, respectively. Clone C219 was less productive due to its higher susceptibility to wind damage, mainly at 9 m layouts. For both clones, the 6,0 m² tree-1 spacing showed the larger production, 212 m3 ha-1 and 92 Mg ha-1, with a drop of 10% and 18% for the 10,5 and 15,0 m2 tree-1 spacing. Forest yield reduced with the increase in between-row spacing, and the 3 m layout, with 34.0 m3 ha-1 yr-1 and 14.6 Mg ha-1 yr-1, was 16% superior to the 9 m one. Yield prediction regression, per clone, was obtained as a function of spacing and layout. A reduction in forest uniformity among trees increased with increasing age, lower spacing and higher rectangularity.

No description available.

Marketplace volatility in the pork industry demands that producers re-evaluate production practices in order to remain profitable. Stocking density and dietary energy concentration independently affect performance and economic returns of growing finishing pigs. However, there is limited information on whether the interaction between these two factors is important for optimizing productivity and maximizing economic returns. The objective of this study was to determine if the dietary energy concentration that maximizes performance and economic returns varies with stocking density. Treatments were arranged as a 2 × 3 × 3 factorial included; sex (barrows and gilts), dietary energy (2.15, 2.30 and 2.45 Mcal NE/kg) and stocking density (14, 17 or 20 pigs per pen providing 0.92, 0.76 and 0.65 m2 per pig, respectively). A total of 932 pigs were used with three replications of 18 treatments. Pigs were randomly assigned to pens within sex to achieve an average initial BW of 75 kg. Wheat and barley based diets were formulated to meet or exceed the pigs’ nutrient requirements (National Research Council, 2012) and were fed in three phases within sex at each energy concentration. Overall (75 to 118 kg BW), as dietary energy increased from 2.15 to 2.45 Mcal NE/kg, ADG increased from 1.17 to 1.23 kg/d, ADFI decreased from 4.09 to 3.77 kg/d, G:F improved from 0.29 to 0.33 and caloric intake increased from 8.81 to 9.29 Mcal NE/d (P < 0.05). When stocking density was increased from 14 to 20 pigs per pen, ADG (1.21 to 1.17 kg/d), ADFI (4.00 to 3.82 kg/d) and caloric intake (9.19 to 8.12 Mcal NE/d) decreased (P < 0.05). Neither dietary energy concentration nor stocking density had a significant effect on the utilization of calories for growth (Gain:Mcal). Feeder visits per pig and time at the feeder per pig were decreased when stocking density increased from 14 to 20 pigs per pen (P < 0.01). Total time at the feeder and time at the feeder per pig were increased when dietary energy decreased from 2.45 to 2.15 Mcal of NE/kg. Per pen, aggressive incidents at the feeder increased (P < 0.05) and there was a tendency for increased aggressive incidents per pig (P = 0.09) when stocking density was increased. There was a linear increase (P < 0.01) in income over feed cost (IOFC) with increased stocking density, and there was a tendency (P = 0.08) for a linear increase in IOFC when dietary energy was increased. The dietary energy which maximized the IOFC did not vary with stocking density. Dietary energy and stocking density independently affect pig performance, behavior, and economic returns and the optimal dietary energy does not depend on stocking density (dietary energy by stocking density interaction).

Walleye (Sander vitreus) is an economically valuable freshwater fish throughout North America. In Alberta, pressure from sport fishing and commercial fishing make effective management and protection of this species crucial to its sustainability. Walleye from 12 Alberta lakes were genetically characterized using 15 microsatellite markers. Each lake contained a genetically distinct walleye subpopulation within a larger population of the river basin in which the lake was situated. Differentiation between subpopulations varied (ST=0.05 to 0.29). Patterns of genetic divergence aligned closely with the current hydro-geographical landscape, except where stocking events have occurred. Vicariance and natal philopatry are likely mechanisms maintaining the current genetic structure. The markers detected sufficient genetic variation between most subpopulations to assign an individual fish to a subpopulation of origin. The utility of genetic assignment was illustrated for stocking assessment and forensic enforcement. These genetic data will help to inform management decisions, monitor population status and enforce harvest restrictions for Alberta walleye. / Systematics and Evolution

Thesis (M.Sc.) - Carleton University, 2008. / Includes bibliographical references (p. 81-104). Also available in electronic format on the Internet.