Stocking Research Papers - Academia.edu (original) (raw)

Since the 1970s, when major improvements to the water quality were made, the River Thames has been subject to a high-profile project aimed at restoring Atlantic salmon to the catchment. Whilst initially successful, with hundreds of salmon... more

Since the 1970s, when major improvements to the water quality were made, the River Thames has been subject to a high-profile project aimed at restoring Atlantic salmon to the catchment. Whilst initially successful, with hundreds of salmon returning each year in the late 1980s, the number of adults returning to the river has declined steeply again in recent years, reaching a low in 2005 when no salmon were recorded. Using a baseline of genetic information gathered from 3830 salmon from throughout their southern European range, and incorporating samples from the hatchery fish used to stock the Thames, all 10 tagged hatchery fish captured in 2003 and all 16 returning untagged adult salmon captured between 2005 and 2008 were assigned to their most likely river of origin. The results suggest that untagged salmon currently ascending the river originate not from exogenous fish stocked into the Thames, but predominantly from other rivers in southern England. This highlights the potential for natural processes of recolonisation to operate in rivers where salmon have become locally extirpated. These findings also underscore several important considerations when undertaking species restoration projects: (i) previous causes of declines must be sufficiently ameliorated to allow new/translocated individuals to thrive, (ii) introduced individuals should originate from a stock that is closely related to the extirpated population, according to the principles of contemporary conservation biology, and (iii) dispersal and gene-flow from neighbouring populations may play a significant role in establishing new populations.► Despite an intensive hatchery stocking programme, since 2005 no hatchery reared salmon have been caught in the Thames. ► Genetic assignment analysis indicates that wild salmon ascending the Thames originate from other rivers in southern England. ► Wild salmon returning to the Thames between 2005 and 2008 do not originate from exogenous fish stocked into the Thames. ► Such straying highlights the potential for natural recolonisation of rivers where salmon have become locally extirpated. ► Our findings highlight the futility of long-term stocking without corresponding improvements in habitat and water quality.

Agriculture being the backbone of not only India and all the countries in the world there are various time to time changes in the cultivation, harvesting and stocking. Though other countries have evolved a lot, India needs to develop in... more

Agriculture being the backbone of not only India and all the countries in the world there are various time to time changes in the cultivation, harvesting and stocking. Though other countries have evolved a lot, India needs to develop in various methods of cultivation and monitoring of farming. There is also a huge scope for the modern technology in the agriculture sector and the monitoring of warehouse. Controlling and monitoring things can be done from anywhere using the network of sensors and internet which is called as Internet of Things (IOT). The systematic arrangement can be used to increase the quality and productivity of modern farming. Henceforth, in this work, we explore the various existing methodologies in this subject and give out the advantages and outcomes of each research.

Why do captive-reared fishes generally have lower fitness in natural environments than wild con- specifics, even when the hatchery fishes are derived from wild parents from the local population? A thorough understanding of this question... more

Why do captive-reared fishes generally have lower fitness in natural environments than wild con- specifics, even when the hatchery fishes are derived from wild parents from the local population? A thorough understanding of this question is the key to design artificial rearing environments that optimize post-release performance, as well as to recognize the limitations of what can be achieved by modifying hatchery rearing methods. Fishes are generally very plastic in their development and through gene–environment interactions, epigenetic andmaternal effects their phenotypeswill develop differently depending on their rearing environment. This suggests that there is scope formodifying con- ventional rearing environments to better prepare fishes for release into the wild. The complexity of the natural environment is impossible tomimic in full-scale rearing facilities. So, in reality, the challenge is to identify key modifications of the artificial rearing environment that are practically and economically feasible and that efficiently promote development towards a more wild-like phenotype. Do such key modifications really exist? Here, attempts to use physical enrichment and density reduction to improve the performance of hatchery fishes are discussed and evaluated. These manipulations show potential to increase the fitness of hatchery fishes released into natural environments, but the success is strongly dependent on adequately adapting methods to species and life stage-specific conditions.

Advantages The Hybrid Model : * Cost saving of 30% on the running costs compared to a traditional RF Drier. * The final quality and softness of the bobbins is the highest one in the market. * This is given by the uniformity of the radio... more

Advantages The Hybrid Model :
* Cost saving of 30% on the running costs compared to a traditional RF Drier.
* The final quality and softness of the bobbins is the highest one in the market.
* This is given by the uniformity of the radio frequency technology combined with the excellent softness given by the low temperature drying process of the air modules.
* In case that the RF machine is stopped for maintenance reasons the customer can continue to drying the product at lower speed only with the use of the forced air modules.

Fish are at the top of aquatic food webs impacting on other biota. Removal of fish by fishing, or stocking the lake with desired fish species has the potential to modify fish populations (their size/age structure, abundance and biomass)... more

Fish are at the top of aquatic food webs impacting on other biota. Removal of fish by fishing, or stocking the lake with desired fish species has the potential to modify fish populations (their size/age structure, abundance and biomass) and various other ecosystem components and thus affect water quality. Analysis of long-term data on the catches of commercially important fish species, stocking of fingerlings, lake water levels, and littoral modifications, allowed revealing the key factors affecting the fish populations, fishing pressure, and mass of landed fish. Long-term decreases in water level negatively affected reproduction and survival of natural/stocked fingerlings of some cyprinids (Mirogrex terraesanctae, Hypophthalamichthys molitrix, Cyprinus carpio) and cichlids (Sarotherodon galilaeus, Oreochromis aureus). In contrast, rapid rises in water level vastly enlarged the areas of inundated terrestrial vegetation and stony/rocky littoral and thus positively affected the reproduction and survival of these fish and their landing after a temporal lag. Fishing pressure on reproductively active large cichlids was enhanced at low water levels due to exposing these fish at spawning time (spring and summer) to fishermen. Such overfishing resulted in lowering the number of reproductively capable cichlids below a certain critical level, leading to a decrease in the reproductive capacity of the population and the collapse of its standing stock (i.e. “recruitment overfishing”). The endemic bleak, Mirogrex terraesanctae is the dominant pelagic zooplanktivore of Lake Kinneret. Large water level fluctuations impacted its reproduction and determined the abundance of this ecologically important species. Bio-manipulation, by mean of subsidized harvesting, implemented to suppress its abundance in critical years, was highly controversial, and was stopped in 2006. Of the stocked grey mullets, Mugil cephalus had lower natural mortality rate, higher growth rate, reached larger sizes, and thus had a higher market value than Liza ramada. Still, fingerlings of the second species were more readily available, such that L. ramada was stocked in larger numbers and was more abundant in the commercial catch. We argue that fish stock management in Lake Kinneret should focus on the restoration of native fish populations and their sustainable fishery.
See also chapter: "Fish Biology and Ecology"

Soil loss by water erosion is the main cause of soil degradation in Brazil. However, erosion can be reduced by the presence of vegetation. The Normalized Difference Vegetation Index (NDVI) makes it possible to identify the vegetative... more

Soil loss by water erosion is the main cause of soil degradation in Brazil. However, erosion can be reduced by the presence of vegetation. The Normalized Difference Vegetation Index (NDVI) makes it possible to identify the vegetative vigor of crops or natural vegetation which facilities the identification of areas with vegetation covers. This information is very
important in identifying the phenomena which might be occurring in a particular area, especially those related to soil degradation by water erosion. Thus, the aim of this work was
to assess the canopy cover by using NDVI, checking the image accuracy using the Coverage Index (CI) based on the Stocking method, in the Sub-basin of Posses, which belongs to the
Cantareira System, located in the Extrema municipality, Minas Gerais, Brazil

Natural bamboo resources in Kenya are about 150,000 ha and they are mainly found on the mountain slopes in the high potential areas in Mt Kenya, Aberdares ranges, Mau escarpment, Cherangani hills and Mt Elgon at high elevations between... more

Natural bamboo resources in Kenya are about 150,000 ha and they are mainly found on the mountain slopes in
the high potential areas in Mt Kenya, Aberdares ranges, Mau escarpment, Cherangani hills and Mt Elgon at high
elevations between 2300 and 3200 meters above sea level. There is only one indigenous bamboo species,
Yushania alpina (formerly Arundinaria alpina). It grows in single culms grouped into clumps. The main use of Y.
alpina bamboo in Kenya is construction and fencing. There is high demand for bamboo for use in horticulture
farming, handcraft, residential fencing, and cottage industry for making furniture, baskets, tooth picks and match
sticks. Some companies have expressed interest in using large amounts of bamboo for bio-energy, panels,
particle boards and pulp. However, bamboo raw material is not available for use because of a Presidential ban
imposed on harvesting bamboo resources in all Government and Trust lands. But even if the ban was lifted,
harvesting of bamboo in the natural forests cannot be prudent because there is very little information on the
quantity, quality and geographical distribution of the available amount. Many entrepreneurs have continued to
request the Government through Kenya Forest Service (KFS) to be allowed to extract natural bamboo for various
uses. On the other front Kenya Forestry Research Institute (KEFRI) has vigorously continued to promote
growing and intensive use of bamboo. These two noble ideas cannot be realized in the absence of the bamboo
resource data. The objective of this study was to develop a yield model that can be used to estimate total bamboo
culms biomass in a given area and the proportion that can be harvested on a sustainable basis. This study used
bamboo data from 25 rectangular temporary sample plots of 10 m x 20 m in natural stands of Y. alpina and trees
at Kieni, Kamae and Kinale in Kiambu County to estimate density and model the dependence of culms
merchantable green weight and oven dry weight on diameter at breast height. The culms mean stoking density
was 21000 culms ha-1. The coefficient of determination (R2
) for green weight model is 0.82 and the root mean
square error (RMSE) is 1.45 kg. The model calculates mean weight of old Y. alpina culm as 9.6 kg.

An effort to increase the production of juvenile catfish is limited by the high mortality rate, especially caused by cannibalism. The hormonal treatment has been conducted as an effort to control cannibalism. This study used completely... more

An effort to increase the production of juvenile catfish is limited by the high mortality rate, especially caused by cannibalism. The hormonal treatment has been conducted as an effort to control cannibalism. This study used completely randomized factorial design, consisted of six treatments and three replications. There were two factors examined in this study, the first factor was different doses of 17β‒estradiol hormone (0, 30, and 60 mg estradiol‒17β/kg) incorporated in the feed, and the second factor was stocking density (150 and 300 fish/m2). Juvenile catfish with the size of 4.0 ± 0.1 cm were reared for 30 days in the 84 L aquarium. The results showed that hormone treatment could reduce cannibalism rate, type-I and II cannibalism compared to control (P<0.05). The results showed that the lowest of mortality was obtained in the treatment B (17β‒estradiol administration of 30 mg/kg, at stocking density of 150 fish/m2; P<0.05). The lowest cortisol level was found in treatme...

In response to declining catches of eels in the brackish Baltic Sea, the Swedish gov- ernment stocks eels Anguilla anguilla (L.), both in lakes (mainly glass eels/elvers) and in the sea itself (mainly yellow eels). However, the degree to... more

In response to declining catches of eels in the brackish Baltic Sea, the Swedish gov- ernment stocks eels Anguilla anguilla (L.), both in lakes (mainly glass eels/elvers) and in the sea itself (mainly yellow eels). However, the degree to which these fish contribute to the spawning stock, if at all, was unknown. We collected silver eels at the exit of the Baltic Sea and analyzed indices of their maturity status. In addition, we used electron (WDS) and nuclear (microPIXE) microprobes to map out the strontium and calcium contents of their otoliths, as Sr:Ca correlates with salinity. As a calibration, we analyzed otoliths from eels collected around the Swedish coast and fresh water (0-25 psu) and derived a relationship between salinity and Sr:Ca. Our results show that, of 86 silver eels analyzed, 17 eels had Sr:Ca profiles consistent with having been stocked into fresh water, six showed patterns consistent with stocking directly into the Baltic from marine waters, and 10 showed patterns...

This study aimed to identify the effect of stocking density on growth, feed efficiency, and survival during the transition from Peruvian grunts (Anisotremus scapularis) fingerlings to juveniles. Fingerlings were reared in triplicate for... more

This study aimed to identify the effect of stocking density on growth, feed efficiency, and survival during the transition from Peruvian grunts (Anisotremus scapularis) fingerlings to juveniles. Fingerlings were reared in triplicate for 63 days until reaching the juvenile stage, at 1000 fingerling·m−3 (low-density LSD, 0.79 kg·m−3), 2000 fingerlings·m−3 (medium-density MSD, 1.58 kg·m−3), and 3000 fingerlings·m−3 (high-density HSD, 2.37 kg·m−3), and production performance parameters were evaluated. At the end of the experiment, results showed a negative correlation between stocking density and growth, individual growth, and the specific growth rate for HSD. The final biomass per treatment was 3.53 ± 0.26, 6.79 ± 0.08, and 7.70 ± 0.46 kg·m−3 for LSD, MSD, and HSD, respectively, the biomass harvest and weight gain were significantly lower for HSD. At the end of the experiment, there was no significant difference in survival (99%) among all treatments. Furthermore, the average food for ...

The research was conducted on June 1 until July 15, 2015 in Aquaculture Technology Laboratory. The aim of research to determine the growth rate and survival rate of fish damselfish (Anabas testudineus) with different stocking density.... more

The research was conducted on June 1 until July 15, 2015 in Aquaculture Technology Laboratory. The aim of research to determine the growth rate and survival rate of fish damselfish (Anabas testudineus) with different stocking density. This study uses a completely randomized design (CRD) with a factor of three levels of treatment, each level of treatment replications performed three times. The treatment given is Betok fish stocking density 15 fish / container or 300 fish / m3, 20 fish / container or 400 fish / m3 and 25 tails / container or 500 fish / m3. To know the development of fish, every 15 days were measured body weight and total length. Observations indicating that the growth and survival of fish damselfish (Anabas testudineus) with different stocking density was not significantly different with the absolute growth of fish, the absolute length growth, and daily growth rate, but significantly different to the survival of fish. The best results in this study is in treatment P3 ...

Abstract Tambaqui (Colossoma macropomum) is the main freshwater species produced in South American aquaculture and is also produced in several Asian countries. The objective of the present study was to evaluate the growth and physiology... more

Abstract Tambaqui (Colossoma macropomum) is the main freshwater species produced in South American aquaculture and is also produced in several Asian countries. The objective of the present study was to evaluate the growth and physiology of juvenile Colossoma macropomum submitted to different stocking densities and classified by size in a recirculating aquaculture system (RAS) to maximize the production and enable the fish rearing in colder regions. In Phase I, juveniles (34.88 ± 0.60 g) were stocked at densities of D0.5 = 0.5, D1.0 = 1.0 and D1.6 = 1.6 kg/m3 for 53 days, and in Phase II, juveniles (150.61 ± 0.58 g) were stocked at densities of D1.5 = 1.5, D3.0 = 3.0 and D4.5 = 4.5 kg/m3 for 60 days. In Phase III, the animals were classified according to size as S = 300–400 g; M = 400–500 g and L ≥500 g for 60 days with an initial biomass of 3.9 kg/m3 for each class. After the first 30 days of Phase I, final weight (FW) and daily weight gain (DWG) were highest for D0.5, but feed conversion rate (FCR) was lowest. Daily feed intake (DC) was the lowest for D1.6 and the highest for D0.5. At 53 days, FW, DC and DWG were highest for D0.5 and lowest for D1.6. From day 31 to day 53 there was a decrease in hemoglobin (Hg) and hematocrit (Htc) and an increase in the hepatosomatic index (HSI) for D0.5. After the first 30 days of Phase II, FW, DWG and DC were highest for D1.5. After 60 days, D1.5 had the highest FW and HSI and lowest values for glucose, triglycerides and Htc (P

Brown trout Salmo trutta is one of the most valuable species inhabiting river drainages in Galicia (northwestern Spain). The influence of man, through overfishing and pollution, is thought to have caused the decline of trout in Galician... more

Brown trout Salmo trutta is one of the most valuable species inhabiting river drainages in Galicia (northwestern Spain). The influence of man, through overfishing and pollution, is thought to have caused the decline of trout in Galician rivers. To balance the possible population decline, Galician rivers have been stocked extensively with a brown trout stock of German origin during the last 30 years. In this study, the incidence of stocking practices has been investigated by an LDH-5* genetic marker. A very low number of stocked individuals have been observed within river populations, despite the long period of repopulation. Only eight out of the 44 populations analysed showed a limited number of individuals of hatchery origin. Most stocked individuals detected were 0+ age, and showed a poor condition factor (K < 1). Environmental factors (muscular stamina and food habits) and genetic factors (different selective conditions in hatchery medium) are invoked to explain the low viability of hatchery fish Observed in this Study.

While stocking floodplain depressions or beels with fingerlings is a common form of fisheries management in Bangladesh, bio-economic guidance for improving the outcome of stocking strategies is sparse. The Community-Based Fisheries... more

While stocking floodplain depressions or beels with fingerlings is a common form of fisheries management in Bangladesh, bio-economic guidance for improving the outcome of stocking strategies is sparse. The Community-Based Fisheries Management (CBFM) Project, funded by the Ford Foundation and the UK Government's Department for International Development (DfID) promoted stocking practices in beels throughout the country as a means to improve fisher livelihoods. This paper describes an empirical bio-economic model developed using data generated under the CBFM project. The model offers guidance on selecting stocking densities depending upon the available size (length) of fingerlings to maximize profit and return on investment while minimizing risk. Because large fingerlings are relatively inexpensive and have lower rates of natural mortality, the model predicts that it is more profitable to stock large fingerlings at low densities than small fingerlings at high densities. These general recommendations were found to be largely insensitive to the market price for harvested fish. To minimize credit burden and financial risk, minimum stocking densities should be selected according to the length of fish available that maximizes profit. Because of its empirical nature, the model recommendations may not be applicable beyond the project sites. Furthermore, it is recommended that attempts be made to field test the model predictions before widespread adoption or promotion.