The Tasmanian Trout Fishery. IV. The Rivers of the South and South-East

1961 ◽  
Vol 12 (1) ◽  
pp. 17 ◽  
Author(s):  
AG Nicholls
Keyword(s):  
Growth Rate ◽  
Total Population ◽  
River System ◽  
Similar Rate ◽  
Population Estimates ◽  
Sea Trout ◽  
Main River ◽  
Spawning Time ◽  
Trout Fishery ◽  
Annual Mortality

Two main river systems are included in this region, the Derwent and the Huon. Data derived from anglers' returns are analysed for each system separately but those from the Huon are insufficient for a thorough study. There is some doubt as to the representativeness of returns from either system. No significant changes have been found in the fishery over a period of 12 seasons either in the rate of daily catch per angler or in the length of fish taken. A study of the fish taken in an upstream trap at spawning time yields an annual mortality rate of about 60% for the Derwent River System and recaptures of tagged fish show a similar rate. Population estimates based on recaptures of tagged fish and on the spawning potential within the system indicate a total population of between one- half and one million, of which about 20% is of takable size. The contribution made by the release of hatchery-reared fish is shown to be insigniiicant. Evidence is produced which leads to the conclusion that there may be two distinct races of trout in Tasmania, the result of separate introductions of river and sea trout, distinguished by inherent meristic differences as well as by differences in growth rate and habits.

PEMBENIHAN DAN AKLIMATISASI PADA SISTEM ANAEROBIK

2018 ◽  
Vol 6 (2) ◽  
Author(s):  
Indriyati Indriyati
Keyword(s):  
Growth Rate ◽  
Total Population ◽  
Fixed Bed ◽  
Support Material ◽  
Anaerobic Process ◽  
Anaerobic Reactor

Seeding in Fixed Bed anaerobic reactor are infl uenced by several condition such as the growth rate total population of microbial, bacterial adaption to infl uent and the retention of biomass in reactor. The aim of this observation is to fi nd out the seeding and acclimation process in anaerobic process by using plastic as support material. Seeding and acclimatization process run smoothly can be seen from the increasing of infl uent or substrate and following by the increasing degradation of soluble COD, beside that the decreasing of VSS concentration indicates that microorganism are all ready fi x in support material, therefore reactor can be operated continuously and the acclimatization process can be stopped.Keywords : anaerobic seeding, acclimation anaerobic process

scholarly journals Mortality in Dementia from 1996 to 2015: A National Registry-Based Cohort Study

2021 ◽  
Vol 79 (1) ◽  
pp. 289-300
Author(s):  
Lærke Taudorf ◽  
Ane Nørgaard ◽  
Gunhild Waldemar ◽  
Thomas Munk Laursen
Keyword(s):  
Elderly People ◽  
Age Groups ◽  
Mortality Rates ◽  
Similar Rate ◽  
National Registry ◽  
Healthcare Data ◽  
Appropriate Care ◽  
People With Dementia ◽  
Rate Ratios ◽  
Annual Mortality

Background: It remains unclear whether the increased focus on improving healthcare and providing appropriate care for people with dementia has affected mortality. Objective: To assess survival and to conduct a time trend analysis of annual mortality rate ratios (MRR) of dementia based on healthcare data from an entire national population. Methods: We assessed survival and annual MRR in all residents of Denmark ≥65 years from 1996–2015 using longitudinal registry data on dementia status and demographics. For comparison, mortality and survival were calculated for acute ischemic heart disease (IHD) and cancer. Results: The population comprised 1,999,366 people (17,541,315 person years). There were 165,716 people (529,629 person years) registered with dementia, 131,321 of whom died. From 1996–2015, the age-adjusted MRR for dementia declined (women: 2.76 to 2.05; men: 3.10 to 1.99) at a similar rate to elderly people without dementia. The sex-, age-, and calendar-year-adjusted MRR was 2.91 (95%CI: 2.90–2.93) for people with dementia. MRR declined significantly more for acute IHD and cancer. In people with dementia, the five-year survival for most age-groups was at a similar level or lower as that for acute IHD and cancer. Conclusion: Although mortality rates declined over the 20-year period, MRR stayed higher for people with dementia, while the MRR gap, compared with elderly people without dementia, remained unchanged. For the comparison, during the same period, the MRR gap narrowed between people with and without acute IHD and cancer. Consequently, initiatives for improving health and decreasing mortality in dementia are still highly relevant.

scholarly journals Short-term movement patterns, population estimates and breeding biology of an island endemic bird, the Tristan Thrush

2019 ◽  
Vol 27 (4) ◽  
pp. 245-252
Author(s):  
Peter G. Ryan ◽  
Ben J. Dilley ◽  
Delia Davies ◽  
Trevor Glass ◽  
Fitsum Abadi
Keyword(s):  
Total Population ◽  
Data Augmentation ◽  
Local Population ◽  
Population Estimates ◽  
Limited Information ◽  
Short Term ◽  
Main Island ◽  
Island Endemic ◽  
Core Study ◽  
Land Bird

AbstractThe Tristan Thrush Turdus eremita is the only land bird that survived human colonisation of the main island of Tristan da Cunha and is listed as “Near Threatened”. Population estimates are confounded by the thrushes’ inquisitive and gregarious nature as well as limited information on their movements. We report the first measures of nest densities on Nightingale Island: 6 nests·ha-1 in Phylica arborea woodland and 4–5 nests·ha-1 in tussock habitat, which suggests that the population is approximately double the previous estimate. At Inaccessible Island, we individually color ringed 110 thrushes over two months to track their short-term movements and estimate the local population size. Individuals moved up to 950 m along the coast, but 96% of resightings were < 100 m. A Bayesian data augmentation approach estimated that some 260 thrushes visited the core study area, a 200-m stretch of cobble and boulder beach where birds come to drink, bathe and forage. This result suggests that the population on Inaccessible Island also is substantially larger than reported previously. We estimate the total population to be 8000–15,000 Tristan Thrushes. The main need is a population estimate for the nominate subspecies on the main island of Tristan.

Paddlefish Management, Propagation, and Conservation in the 21st Century

2009 ◽  
Keyword(s):  
Growth Rate ◽  
Population Dynamics ◽  
Mortality Rate ◽  
Population Density ◽  
21St Century ◽  
High Growth ◽  
High Growth Rate ◽  
Demographic Groups ◽  
Annual Mortality ◽  
Remnant Population

<em>Abstract</em>.—Paddlefish <em>Polyodon spathula </em>vanished from areas of the upper Tombigbee River basin in Mississippi and Alabama during the 1950s, long before channelization and damming associated with construction of the Tennessee-Tombigbee Waterway (TTW) were completed in 1984. This study was undertaken to assess distribution and population dynamics of any remaining stock. Paddlefish were not captured in upstream impoundments, but an unexploited remnant population was located in the downstream impoundment: Demopolis Lake, Alabama. Paddlefish in Demopolis Lake were characterized by a population density of 2.6 fish/ha, high growth rate relative to more northern populations, and natural annual mortality rate (<em>A </em>= 0.406) similar to other southern populations. Two wintering habitats (cutoff bendways) were heavily utilized by paddlefish. Large males primarily inhabited the more lotic bendway while females and small males were more common in the more lentic bendway, indicating differential importance of habitats among demographic groups. The restricted distribution of TTW paddlefish and demographic differences between habitats suggest that areas heavily utilized by paddlefish should be protected from further degradation. Sedimentation has resulted in reductions of bendway depth and reduced connectivity of backwaters, reducing availability of suitable paddlefish habitat. Restoring connectivity of bendways through dredging could reverse this trend and provide other benefits to fisheries.

scholarly journals Psychiatry in Iran

2005 ◽  
Vol 2 (10) ◽  
pp. 10-12 ◽  
Author(s):  
Majid Sadeghi ◽  
Gholamreza Mirsepassi
Keyword(s):  
Growth Rate ◽  
Rural Areas ◽  
Persian Gulf ◽  
Population Growth Rate ◽  
Total Population ◽  
Islamic Republic ◽  
Land Area ◽  
The Caspian Sea ◽  
Islamic Republic Of Iran ◽  
The Persian Gulf

The Islamic Republic of Iran is located in the Middle East between the Caspian Sea and the Persian Gulf. Iran's total land area is 1 648 000 km2. Its total population in 2003 was about 68 920 000 (UNICEF, 2003). The population growth rate is 1.41%. Of the total population, 60.4% live in urban and 39.6% in rural areas (Yasamy et al, 2001).

The Tasmanian Trout Fishery. III. The Rivers of the North and East

1958 ◽  
Vol 9 (2) ◽  
pp. 167 ◽  
Author(s):  
AG Nicholls
Keyword(s):  
Growth Rate ◽  
Age Distribution ◽  
Total Catch ◽  
River Systems ◽  
The North ◽  
Full Capacity ◽  
The Mean ◽  
Trout Fishery ◽  
Distribution Of Fish

The study of the daily catch from the Korth and South Esk River systems, as derived from anglers' returns, shows a general fall which appears to be statistically significant in all rivers except the Meander. It appears to become increasingly important from west to east. It is accompanied by a fall in the annual catch per angler which is closely correlated with an increase in the number of licences issued, from which it might appear that these streams are being fished to their full capacity. A study of the mean lengths of fish at capture does not show any decrease compatible with over- fishing, and there has been no increase in growth rate, which might be expected under conditions of overfishing. The age distribution of fish caught bv anglers does not indicate any decrease in the proportions of older fish. A personal canvass of 53 anglers in one district showed a mean total catch per angler of 259 fish, whereas the figure derived from anglers' returns for the same season was 20 fish per angler. It is concluded that the apparent decline in catching rate was due to the returns from anglers being unrepresentative. So correlation was found between the catches by anglers and the fish available to them as a result of stocking these streams.

High prevalence of non-native fish species in a remote region of the Mamberamo River, Indonesia

2020 ◽  
Vol 26 (3) ◽  
pp. 293
Author(s):  
Arif Wibowo ◽  
Dwi Atminarso ◽  
Lee Baumgartner ◽  
Anti Vasemagi
Keyword(s):  
Native Species ◽  
River System ◽  
New Guinea ◽  
Current Status ◽  
Native Fish ◽  
Fish Diversity ◽  
Main River ◽  
Main River Channel ◽  
High Prevalence ◽  
Major River

Indonesian freshwater fish diversity is threatened by human activities such as logging, land clearing, pollution and introduction of non-native species. The latter may pose serious threats to endemic freshwater fauna even in relatively pristine and isolated habitats. One such area, West Papua in the island of New Guinea, is one of the least studied regions in the world and a biodiversity hotspot. The Mamberamo River contains the highest proportion of non-native fish compared to other major river systems in New Guinea. To document this, we conducted a field study to validate and further temporally characterise the fish biodiversity to ascertain its current status. Since the last ichthyological survey 15 years ago, we detected two additional non-native species (Leptobarbus melanopterus and Oreochromis niloticus) that have established in the river system. Moreover, our survey revealed that non-native fish are extremely common in the mid reaches of the Mamberamo River, comprising 74% of total catch, with non-native Barbonymus gonionotus (family Cyprinidae) now established as the dominant species. The biomass of non-native B. gonionotus now exceeds that of all native fish combined in the main river channel. These results highlight the serious threat of invasive species in remote regions that support high levels of endemic biodiversity. Plans for containment, prevention through education programmes, and management are urgently required.

scholarly journals Facies association and depositional environment of fan-delta sequence in southwest Kathmandu Basin, Nepal

1970 ◽  
Vol 12 ◽  
pp. 1-16
Author(s):  
Naresh Kazi Tamrakar ◽  
Pramila Shrestha ◽  
Surendra Maharjan
Keyword(s):  
River System ◽  
Sedimentary Facies ◽  
Facies Association ◽  
Base Level ◽  
Rock Types ◽  
Fan Delta ◽  
Main River ◽  
Facies Associations ◽  
Delta Sequence ◽  
The Difference

Lake marginal sedimentation prevailed around the Paleo-Kathmandu Lake. Owing to the difference in local basin conditions; tectonics, source rock types and river systems therein, the lake marginal environments and sedimentary facies associations differ around the Paleo-Kathmandu Lake. In this study, the basin-fill sediments of southwestern margin of the Kathmandu Basin were studied for the sediments recorded in vertical sequences at various localities and facies analysis was made. Mainly eight facies were recognised. They were matrix-supported massive gravel (Gmm), matrix-supported graded gravel (Gmg), gravelly fine or mud (GF), massive silt (Fsm), massive mud (Fm), ripple-laminated silt or laminated silt/mud/clay (Fl), carbonaceous clay (C), and incipient soil with roots (Fr). Four facies associations that were identified were proximal fan-delta facies association (FA1), mid fan-delta facies associaiton (FA2), distal fan-delta facies association (FA3), and gravelly sinuous river facies association (FA4). Remarkably, these facies associations do not contain any sandy facies and foreset bedding of Gilbert-type. The fan-delta region was characterised by flood-dominated flows and vertical accretion of fines in the flood basins, and vegetated swamps rich in organic sediments. The distribution of facies associations suggests extensive lake transgression followed by rapid lake regression. The recent river system then incised the valley against local upliftment due to faulting or lowering of base level of the main river in the Kathmandu Basin probably related to draining out of the lake water. doi: Bulletin of the Department of Geology, Vol. 12, 2009, pp. 1-16

Reproductive Behaviour of Sea Trout (Salmo Trutta) - the Consequences of Sea-Ranching

Behaviour ◽  
1997 ◽  
Vol 134 (1-2) ◽  
pp. 1-22 ◽  
Author(s):  
Torbjorn Järvi ◽  
Erik Petersson
Keyword(s):  
Mating Success ◽  
Salmo Trutta ◽  
Dominance Hierarchy ◽  
Stream Water ◽  
Reproductive Behaviour ◽  
Factors Associated ◽  
Sea Trout ◽  
Sea Ranching ◽  
Spawning Time ◽  
Morphological Differences

AbstractReproductive behaviour and factors associated with male and female mating success were studied in sea trout (Salmo trutta) in a stream water aquarium, during three successive years. We compared a sea-ranched and a wild-produced strain, both of the same genetic origin. In general, dominant males courted females more often, spent more time on the spawnable areas, and had higher mating success than lower ranked males. Body mass explained about 18% of the males' position in the dominance hierarchy. Sea-ranched males, however, achieved on average fewer matings than wild ones. Wild males courted the nest-preparing females and chased away other males more frequently than did the sea-ranched males. Females were observed to be aggressive towards males, especially when the females were preparing a nest. The males that were more frequently the target of female aggression had smaller adipose fins and were more often aggressive towards females. In general the females spawned just once in each nest. Sea-ranched females defended and tested their redd less frequently than the wild females did. Digging activity by wild females diminished closer to spawning time, but not that of the sea-ranched females. To what extent the observed differences were due to the environmental conditions or to genetic differences is not known at present. However, the results of previous studies have revealed that behavioural and morphological differences exist between the strains, despite being reared under the same conditions. Thus, the behavioural changes noted in the sea-ranched sea-trout might have a genetic element.

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