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J. R. M. Kelso - One of the best experts on this subject based on the ideXlab platform.
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Fish Production in freshwaters : are rivers more productive than lakes ?
Canadian Journal of Fisheries and Aquatic Sciences, 1995Co-Authors: Robert G. Randall, Charles K. Minns, J. R. M. KelsoAbstract:Community Fish Production data were summarized from the literature to test the hypothesis that Production is higher in rivers than in lakes. Average community Production at 55 river sites was three times greater (273 kg∙ha−1∙year−1) than at 22 lakes (82 kg∙ha−1∙year−1). Higher Production (P) in rivers resulted from much higher densities of Fish (14 times) and greater biomass (B) (about 2 times). Average Fish weight and P/B ratios were inversely correlated. Average Fish weight was 7 times less, and P/B ratios were 1.5 times higher (after correction for Fish size), in rivers than in lakes. Thus, rivers not only had higher average biomasses of Fish but also the turnover rate of the biomass was greater. Fish Production was positively correlated with phosphorus in both lakes and rivers. Information on community Fish Production supported the hypothesis that the productivity of river habitat is, on average, higher than the productivity of lake habitat. The productive capacity of freshwater habitats can be predic...
C.j.s. Pannu - One of the best experts on this subject based on the ideXlab platform.
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Energy requirements in Fish Production in the state of Punjab
Energy Conversion and Management, 1998Co-Authors: Surendra Singh, C.j.s. PannuAbstract:Abstract A study was performed in the Patiala District of Punjab to evaluate the energy requirements in Fish Production. For this study, a total of eight farmers were selected randomly. The ponds were stocked by the farmers with fingerlings of the species ‘Katla’, ‘Rohu’, ‘Murrak’, ‘Silver carp’ and ‘Golden’. Data regarding all operations, from pond preparation to Fish harvesting, were collected. The total energy input in Fish farming varied between 86385–162503 MJ/ha with an average value of 125243 MJ/ha including pond construction and initial water filling. However, pond construction and water filling operations are done only once, and the water level is maintained from time to time. Therefore, excluding these two operations, the energy required in Fish Production was found to be in the range of 5495–14117 MJ/ha with an average value of 9121 MJ/ha. The Production of Fish varied between 4050–4520 kg/ha with an average value of 4291 kg/ha. This level of Production gave the energy-ratio of 1.36–3.14 with the mean value of 2.00.
Marc C.j. Verdegem - One of the best experts on this subject based on the ideXlab platform.
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The potential of Fish Production based on periphyton
Reviews in Fish Biology and Fisheries, 2002Co-Authors: Malcolm C.m. Beveridge, M. Ekram Azim, Marc C.j. VerdegemAbstract:Periphyton is composed of attached plant andanimal organisms embedded in amucopolysaccharide matrix. This reviewsummarizes research on periphyton-based FishProduction and on periphyton productivity andingestion by Fish, and explores the potentialof developing periphyton-based aquaculture.Important systems with periphyton arebrush-parks in lagoon areas and freshwaterponds with maximum extrapolated Fish Productionof 8 t ha^−1 y^−1 and 7 t ha^−1y^−1, respectively. Experiments with avariety of substrates and Fish species havebeen done, sometimes with supplemental feeding.In most experiments, Fish Production wasgreater with additional substrates compared tocontrols without substrates. Colonization ofsubstrates starts with the deposition oforganic substances and attraction of bacteria,followed by algae and invertebrates. Afterinitial colonization, biomass density increasesto a maximum when competition for light andnutrients prevents a further increase. Often,more than 50% of the periphyton ash-free drymatter is of non-algal origin. Highest biomass(dm) in natural systems ranges from 0 to 700g m^−2 and in aquaculture experiments wasaround 100 g m^−2. Highest productivity wasfound on bamboo in brush-parks (7.9 gC m^−2 d^−1) and on coral reefs (3 gC m^−2 d^−1). Inorganic and organicnutrients stimulate periphyton Production.Grazing is the main factor determiningperiphyton density, while substrate type alsoaffects productivity and biomass. Better growthwas observed on natural (tree branches andbamboo) than on artifical materials (plasticand PVC). Many herbivorous and omnivorous Fishcan utilize periphyton. Estimates of periphytoningestion by Fish range from 0.24 to 112 mg dm(g Fish)^−1 d^−1. Ingestion rates areinfluenced by temperature, Fish size, Fishspecies and the nutritional quality of theperiphyton. Periphyton composition is generallysimilar to that of natural feeds in Fishponds,with a higher ash content due to the entrapmentof sand particles and formation of carbonates.Protein/Metabolizable Energy (P/ME) ratios ofperiphyton vary from 10 to 40 kJ g^−1.Overall assimilation efficiency of Fish growingon periphyton was 20–50%. The limited work onfeed conversion ratios resulted in valuesbetween 2 and 3. A simple simulation model ofperiphyton-based Fish Production estimates FishProduction at approximately 2.8 t ha^−1y^−1. Together with other food resources inFishponds, total Fish Production with thecurrent technology level is estimated at about5 t ha^−1 y^−1. Because grazingpressure is determined by Fish stocking rates,productivity of periphyton is currently themain factor limiting Fish Production. Weconclude that periphyton can increase theproductivity and efficiency of aquaculturesystems, but more research is needed foroptimization. Areas for attention include theimplementation and control of periphytonProduction (nutrient levels, substate types andconformations), the ratio of Fish to periphytonbiomass, options for utilizing periphyton inintensive aquaculture systems and with marineFish, and possibilities for periphyton-basedshrimp culture.
Eseoghene Olaifa - One of the best experts on this subject based on the ideXlab platform.
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Effects of oil spills on Fish Production in the Niger Delta
PloS one, 2018Co-Authors: Eze Simpson Osuagwu, Eseoghene OlaifaAbstract:The Niger Delta region is the oil producing area of Nigeria, which consists of highly diverse ecosystems that are supportive of numerous species of terrestrial and aquatic fauna and flora. Crude oil spills endanger Fish hatcheries in coastal water and also contaminate valuable Fish. This study examines the effects of oil spills on Fish Production in the Niger Delta of Nigeria from 1981–2015 using an estimable Cobb Douglas Production function. The findings suggest that oil Production and spills negatively affect Fish Production, while farm labour has a positive effect on Fish Production. On the other hand, Fishery loan exerts a negative effect on Fish Production and this could be ascribed to the bottlenecks in accessing these loans. This study corroborates the findings in literature on the negative concomitance of oil spills and Fish Production and suggests a cautious approach to oil exploration activities for a sustainable development in the region.
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EFFECTS OF OIL SPILLS ON Fish Production IN THE NIGER DELTA OF NIGERIA
2017Co-Authors: Eseoghene Olaifa, Eze Simpson OsuagwuAbstract:The oil producing area of Nigeria, known as the Niger Delta region consist of highly diverse ecosystems that is supportive of numerous species of terrestrial and aquatic fauna and flora. The region is the largest wetland in Africa and it is among the ten most important wetlands and marine ecosystems in the world. Incident of oil spill raises concern about seafood safety. Crude oil endangers Fish hatcheries in coastal water and also contaminates commercially valuable Fish flesh. Hence, this study examines the effects of oil spills on Fish Production in Niger Delta of Nigeria from 1981-2015 by using an estimable Production function based on a Cobb Douglas Production function model. The variables included in the model are captured Fish Production, number of Fishers, loan to Fishery, oil spills data and oil Production data sourced from FAOSTAT, CBN and Department of Petroleum Resources (DPR) respectively. The findings established that oil spills and oil Production negatively affect Fish Production, while labour positively affects Fish Production. On the other hand, Fishery loan exerts a negative effect on Fish Production and this can be ascribed to the bottlenecks in trying to access these loans. Looking at the Pairwise Granger Causality test result, it was established that the number of times oil is spilled on the environment affect the level of Fish Production negatively.
Brian R. Mackenzie - One of the best experts on this subject based on the ideXlab platform.
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Has eutrophication promoted forage Fish Production in the Baltic Sea?
Ambio, 2016Co-Authors: Margit Eero, Helén C. Andersson, Elin Almroth-rosell, Brian R. MackenzieAbstract:Reducing anthropogenic nutrient inputs is a major policy goal for restoring good environmental status of coastal marine ecosystems. However, it is unclear to what extent reducing nutrients would also lower Fish Production and Fisheries yields. Empirical examples of changes in nutrient loads and concurrent Fish Production can provide useful insights to this question. In this paper, we investigate to what extent a multi-fold increase in nutrient loads from the 1950s to 1980s enhanced forage Fish Production in the Baltic Sea. We use monitoring data on Fish stock dynamics covering the period of the nutrient increase, combined with nutrient concentrations from a 3-dimensional coupled physical-biogeochemical ocean model. The results suggest that nutrient enrichment enhanced the biomass level of forage Fish by up to 50 % in some years and areas due to increased body weight of Fish. However, the trends in Fish biomasses were generally decoupled from changes in nutrient concentrations.
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Has eutrophication promoted forage Fish Production in the Baltic Sea?
Ambio, 2016Co-Authors: Margit Eero, Helén C. Andersson, Elin Almroth-rosell, Brian R. MackenzieAbstract:Reducing anthropogenic nutrient inputs is a major policy goal for restoring good environmental status of coastal marine ecosystems. However, it is unclear to what extent reducing nutrients would also lower Fish Production and Fisheries yields. Empirical examples of changes in nutrient loads and concurrent Fish Production can provide useful insights to this question. In this paper, we investigate to what extent a multi-fold increase in nutrient loads from the 1950s to 1980s enhanced forage Fish Production in the Baltic Sea. We use monitoring data on Fish stock dynamics covering the period of the nutrient increase, combined with nutrient concentrations from a 3-dimensional coupled physical-biogeochemical ocean model. The results suggest that nutrient enrichment enhanced the biomass level of forage Fish by up to 50 % in some years and areas due to increased body weight of Fish. However, the trends in Fish biomasses were generally decoupled from changes in nutrient concentrations.