Academic literature on the topic 'Self-stocked ponds'

A&nbsp;study was conducted to determine fish yields from flood depended ponds in Rufiji floodplain, Tanzania. Eight ponds were constructed during dry season in two sites besides two floodplain lakes, Ruwe and Uba. These ponds were self-stocked with different fish species from the lakes. More than eight species were trapped and<em>Oreochromis urolepis, Labeo congoro and Clarias</em>&nbsp;species were considered as good candidates for aquaculture. Other small fish species were harvested immediately after flood recession and the three key species were cultured for the maximum of seven months. However, other species in small quantities were remained in the ponds for the whole period of experiment. Water quality parameters were monitored throughout the study period. The relationships between water quality variables and flooding events were determined using canonical correspondence analysis (CCA). Other parameters included in the relationships were fish density, manure and number of species trapped and cultured. Dissolved oxygen and pH decreased with time in both sites. Fish yields were influenced by some water quality, flooding episode and other management variables. Chlorophyll-<em>a</em>&nbsp;was the only environmental variable that showed a significant correlation with fish yield (P&lt; 0.01).&nbsp; Fish density and number of species trapped showed a significant effect on the fish yield (P&lt;0.05). Re-connectivity between ponds and lakes was strongly positively correlated with yield. It can be concluded that some water quality variables, flooding and management parameters were responsible for the observed yield.

To study the big and Small Indigenous Species (SIS) of fish production, 15 ponds of Rajshahi University campus were selected. The pond production was ranged from 326.16 to 2187.40 kg/ha. The ratio of SIS and big fish production was calculated maximum as 1 : 0.10 (by number) and 1 : 7.46 (by weight). Majority of these SIS fish are Self Recruiting Species (SRS), because they were not stocked in the studied ponds. The F/C ratio was obtained as 4.583 in averageDOI: http://dx.doi.org/10.3329/ujzru.v31i0.15378Univ. j. zool. Rajshahi Univ. Vol. 31, 2012 pp. 27-30

Density-dependent mortality in young life stages should strongly limit the potential for additive effects caused by stocking of fish sizes that are smaller than size at recruitment into the fishery. Indeed, stocking models have suggested that stocking of fry should not elevate year class strength in self-sustaining stocks. However, limited data based on replicated and controlled experiments are available to support this prediction. We performed a pond experiment (N = 4 per treatment) to compare the stock enhancing outcome of stocking hatchery-reared northern pike (Esox lucius) fry and the natural production of young in self-recruiting pike populations. We also added a treatment where pike fry were stocked into ponds that otherwise did not have pike to mimic the absence of natural recruitment. Fry stocking into self-reproducing stocks did not elevate year class strength over unstocked controls. However, in the absence of competition, year class strength of juveniles in late summer emerging from fry stocking was similar to the production of natural recruits. Overall, we demonstrated the competitive disadvantage of hatchery-reared fry when released into waters already containing natural recruits, the partial replacement of natural recruits by hatchery-reared fry, and the lack of additive effects of stock enhancement in naturally reproducing stocks. A stock-enhancing effect of pike fry stocking may only be expected in the absence of natural recruitment.

&lt;p&gt;Many hatcheries successfully produced and sold cherax as ornamental crayfish. The attempt to culture cherax in earthen pond to produce consumable size yabbies facing the fact that cherax is a good hole digger and usually escapes through the hole in dyke. Single-o-shelter meant to provide shelter for every single spawner as well as hideout for the juvenile produced. The shelter for spawner was a 25 inches long and 2.0 inches diameter PVC pipe randomly spread on pond bottom. Aquatic weed (Vallisneria torta) grew in the shallow part of pond to provide hiding place for juvenile. The species stocked is huna and redclaw, each at density of 2 and 6 sets of spawner. One set of spawner consists of 3 males and 5 females weighing averagely around 20 g each. The experimental units are randomly selected to facilitate random block design in 2 rearing period as replicate. The pond dimension is 10 m x 10 m, divide into 3 compartments i.e. feeding, ground, nursery ground and harvest ditch. Water depth at nursery ground was 30 cm and at the other compartments at 60 cm. Follow gravity force, the water in ponds flows at 50—100 L minute-1. Self-made diet distributed into pond twice a day to meet 3% daily feeding ration. Survival rate and specific growth rate of spawner as well as juvenile produced and number of gravid female checked at the end of each rearing period or every 3 months. After 6 months, average weight of redclaw and huna reaching 146.12 ± 34.47 g and 103.7 ± 29.83 g, respectively. Redclaw produced progeny of 5 size groups and huna produced only 2 groups. Respective to the species, average weight of the first offspring batch was 39.03 ± 5.33 and 26.83 ± 2.09 g. Redclaw at 2 sets of spawner and male grow faster than of 6 sets of spawner and female. No survival rate significant difference among ponds indicates that single–o-shelter technique provides sufficient shelter for spawner to grow and reproduce. Male monosex redclaw culture in earthen pond seems to be more promising than mixed-sex and female monosex culture for consumable size production of either huna or redclaw.&lt;/p&gt;