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Fisheries Report No 71 - An Investigation Of The Mortality Of The Pearl Oyster, Pinctada Maxima, In Western Australia, Rand Dybdahl, David A. Pass

Fisheries Research Reports

A three year investigation into the cause of abnormally high mortality rates of the pearl oyster, Pinctada maxima, on the cultured pearl industry's lease sites in the North West of Western Australia was completed on 30 June 71983. The objective of this study was to determine environmental, physiological and pathological factors predisposing farm oysters to excessive Levels of mortality and, if possible, make recommendations to alleviate this problem.

As mass mortalities may have complex causes, complementary field and laboratory studies were instigated. The culture industry's method of collection, transportation and farm husbandry were examined. Environmental parameters were monitored. Various empirical …

A Proposal To Fertilize The Overton Arm And Gregg Basin Areas Of Lake Mead, Larry J. Paulson

Publications (WR)

Several limnological studies have been conducted in Lake Mead during the past decade. The recent studies clearly show that most of Lake Mead is deficient in nutrients, especially phosphorus, and very low in productivity. The reservoir-wide average total phosphorus concentration for 1981 - 1982 was only 9 mg/m³. This is below levels found In most oligotrophic lakes and reservoirs. Algal biomass, as measured by chlorophyll-a, averaged only 1.5 mg/m³. That also places Lake Mead in the oligotrophic range. Transparency, as measured by a Secchi disc, averaged 9-5 m in Lake Mead during 1981-1982. That far exceeds …

Seasonal And Spatial Heterogeneity In The Limnetic Zooplankton Community Of Lake Mead, Gene Robert Wilde

Publications (WR)

Zooplankton samples collected from throughout Lake Mead, in 1981-1982, demonstrate the presence of a statistically significant seasonal and spatial heterogeneity in zooplankton densities. Seasonally, the major zooplankton groups were most abundant in the spring and fall, coincident with maxima in chlorophyll-a concentrations. Successions among the various rotifers, cladocerans and copepods present in the reservoir were influenced by food availability, diapause, predation by planktivorous fish and, possibly, water temperatures. Spatial heterogeneity in zooplankton densities was unrelated to water temperature, pH, conductivity and dissolved oxygen concentrations, but was related to the abundance of phytoplankton (chlorophyll-a concentrations) and fish. Statistical analyses indicate that …

The Role Of Nannoplankton In The Phytoplankton Dynamics Of Four Colorado River Reservoirs (Lakes Powell, Mead, Mohave, And Havasu), Jeffrey John Janik

Publications (WR)

Phytoplankton species composition and community size structure were studied in four warm-monomictic Colorado River reservoirs; lakes Powell, Mead, Mohave, and Havasu from March 1981 to February 1982. Sampling was done at approximately monthly intervals from several stations in each reservoir. The Utermohl technique was used to enumerate phytoplankton. The phytoplankton assemblage was divided into the following six size classes using microscopic techniques; netplankton (>64 um), and nannoplankton (>5, 5-11, 12-21, 22-44, and 45-64 um).

Total phytoplankton biomass and community size structure were different among these four reservoirs with considerable spatial and temporal variation present. Average reservoir-wide areal weighted …

Las Vegas Wash Multispectral Scanner Survey, T. H. Mace, M. V. Olsen, Environmental Protection Agency

Publications (WR)

At the request of the U.S. Bureau of Reclamation, Boulder City, Nevada, the U.S. Environmental Protection Agency's Environmental Monitoring Systems Laboratory at Las Vegas collected multispectral scanner imagery of Las Vegas Wash on October 1, 1982. A combined maximum likelihood classification and editing procedure was used to classify the multispectral scanner imagery into 12 categories of land cover. The classification identified four categories of marsh vegetation, one category of riparian, two categories of mixed scrub, and two desert categories. Turbid water and cultivated land formed an "other" category. Area tabulations were formed by georeferencing the classification to the Universal Transverse …

Fisheries Report No 66 - The Fishery For Perth Herring, Nematalosa Vlaminghi (Munro), C F. Chubb, N. G. Hall, R C.J. Lenanton, I. C. Potter

Fisheries Research Reports

Perth herring fishery over the last 30 years have been examined. While there are pockets of catches between Broome and Bunbury, those from the Swan Estuary and nearby inshore marine waters make by far the most important contribution to the fishery. In the Swan Estuary, the catches started rising in the 1950s in response to a demand by the rock lobster industry for bait and reached peak values in the late 1960s and early 1970s. Data are provided which demonstrate that catch per boat is a good index of catch per unit effort (CPUE) in the period since 1967 when …

Fisheries Report No. 65 - The Amateur Fishery For Marron (Cherax Tenuimanus) In Western Australia - Summary Of Logbook Data 1971-83, N. Morrissy, C. Fellows, N. Caputi

Fisheries Research Reports

The large, native crayfish called marron, Cherax tenuimanus, supports an extensive recreational fishery in the southwest of Western Australia. This report examines annual catch and effort statistics gathered from a Logbook programme, initiated in the 1971/72 season and supplemented by an end of season telephone survey from 1977. Logbook data gave estimates of relative abundance, but were too biased for projection to total catch and effort for the fishery, while telephone surveys gave unbiased estimates of total annual fishing effort (trips)l.

Relative abundance showed a significant decline in the major rivers and the most popular dam (Wellington) over the monitoring …

Fisheries Report No 60 - Amateur Net Fishing Survey Of Two Western Australian South Coast Estuaries In January 1981, D. I. Heald

Fisheries Research Reports

Following the return of the administration of fishing activities in Wellstead estuary and Beaufort Inlet to the Western Australian Government in October 1980, a survey of the amateur net fishing in these two estuaries was undertaken in January 1987, The purpose of the survey was to document usage, species catches and size composition of fish caught in respect of mesh size used and the success rate of amateur net fishermen as compared to their expectation. At the time of the survey, Wellstead estuary had been closed to the sea for 13 months and Beaufort Inlet for 27 months and the …

Fisheries Report No 63 - Assessment Of Artificial Feeds For Battery Culture Of A Freshwater Crayfish, Marron (Cherax Tenuimanus) (Decapoda: Parastacidae), Dr N. Morrissy

Fisheries Research Reports

Performance of juvenile crayfish, 0.1-5 g, on a variety of commercial crustacean feeds was tested under conditions of individual housing ("battery culture"), where sources of additional feed were minimized (detritus), or eliminated (cannibalism) Survival was close, or equal, to 100% over 50 day test periods, a reflection of optimal battery conditions rather than feeding, since survival over 100 days for an unfed (control} group was also 100%. No ecdysiad mortality, or trauma, occurred with crayfish, up to 10g, in compartments of area 75 cm. Growth performance in tests was rated by separate ratios for ecdysial increment and frequency, relative to …

Fisheries Report No 64 - The Western Rock Lobster Fishery 1977 - 1978, R. S. Brown, E H. Barker

Fisheries Research Reports

The fishery for the western rock lobster Panulirus cygnus is one of the most important single fisheries in Australia and an important export earner for the State. The fishery is governed by a complex set of regulations which have been reviewed by Bowen (1971) and which are designed to limit the total fishing effort to acceptable levels and to enforce a legal minimum size. It is thus important to constantly monitor the state of the fishery both to ensure that the effort is remaining within the accepted limits and that the regulations are adequately performing their function of maintaining reasonably …

Fisheries Report No 67 - The Western Rock Lobster Fishery 1978 - 1979, R. S. Brown, E H. Barker

Fisheries Research Reports

The fishery for the western rock lobster Panulirus cygnus is one of the most important single fisheries in Australia and an important export earner for the State. Western Australia produced a record 11 388 tons in 1978/79, out of a total Australian catch of rock lobster of 15 400 tons. The fishery is governed by a complex set of regulations which have been reviewed by Bowen (1971) and Hancock (1981) and which are designed to limit the total fishing effort to acceptable levels and to enforce a legal minimum size. It is thus important to constantly monitor the state of …

Research Objectives In Vertebrate Pest Control, A J. Oliver

Journal of the Department of Agriculture, Western Australia, Series 4

The European rabbit, introduced into Australia in 856 by an early settler for hunting, caused massive losses to agricultural production in Western Australia in 1940s and 1950s.

In those years most of the country's recources and efforts allocated to vertebrate pest problems were aimed at controlling this animal.

Research and control measures by Commonwealth and State agencies, including the introduction of myxomatosis, were largely responsible for reducing the rabbit problem to the comparatively minor one it is now.

Today, the Agricultural Protection Board is involved in the control of a much wider range of mammals and birds which cause losses …

Rabbit Kitten Survival In The South-West, D R. King

Journal of the Department of Agriculture, Western Australia, Series 4

In the South-West of Western Australis reliable winter rains allow the rabbit breeding season to extend through winter and spring, and thus a large number of kittens are produced each year.

Studies on the biology of rabbits at Cape Naturaliste (270 kilometres south-west of Perth) and Chidlow (40 kilometres east of Perth in the Datling Range) have shown that at these sites each doe produces about 30 and 27 kittens respectively a year. If all these youg rabbits survived, there would be a 15-fold increase in numbers. Within a short time the State would be covered "wall to wall" by …

Rabbits North Of Carnarvon, D R. King

Journal of the Department of Agriculture, Western Australia, Series 4

In Westeern Australia rabbits are mainly a pest along the south-western coastal parts of the State, but there are populations north of the Tropic of Capricorn. Rabbits after crossing the Nullarbour plain from South Australia and colonising the South-West of the State, were reported to have reached the west coast near Geraldton by 1912 and then spread northwards.

There is little information on the biologhy of rabbits in the northan parts of their range, but pastoralists in some areas are concerned about erosion and damage to vegetation on their stations when rabbits reach high numbers.

The Agricultural Protection Board undertook …

Myxomatosis In Western Australia, D R. King, S. H. Wheeler

Journal of the Department of Agriculture, Western Australia, Series 4

Since myxomatosis was introduced to Western Australia in the early 1950s rabbit plagues have ceased. However, myxomatosis has not proven to be the whole answer to the rabit problem.

Rabits continue to damage crops and pastures in many areas and resurgences of rabbit populations are reported from time to time.

Drs D.R. King and S. H. Wheeler of the Agricultural Protection Board's research section have been studying the way myxomatosis epidemics occur and spread in rabbit populations in a range of Western Australian environments. This research will provide data for planning effective control strategies intergrating the various control options available …

Feral Donkeys : An Assessment Of Control In The Kimberley, S H. Wheeler

Journal of the Department of Agriculture, Western Australia, Series 4

Feral donkeys are one of the major limitations to increased pastoral production in many parts of the Kimberley area of Western Australia, where they compete with cattle for food. In addition donkeys are aggressive animals, driving cattle from watering points and better grazing areas. They eliminate perenial plants by overgrazing and therefore reduce the carrying capacity of the range.

Originally introduced as draught animals, donkeys were released when cars arrived; since then they have bred up to large numbers in many areas.

For several years the Agricultural Protection Board has undertaken a programme of donkey shooting from helicopters. Since this …

Breeding Birds In Cedar Stands In The Great Dismal Swamp, Karen A. Terwilliger, Robert K. Rose

Biological Sciences Faculty Publications

The Great Dismal Swamp located in the coastal plain on the Virginia- North Carolina border, has long been recognized as a vegetationally distinctive region with many unusual geological and biological features. Formerly at least twice the currently estimated size of 85,000 hectares (Carter 1979), the Great Dismal Swamp is still shrinking because of a dropping water table caused by more than 200 years of logging, ditching, and other human activities. In 1973, the Union Camp Corporation donated a 19,871-hectare tract located near Suffolk, Virginia. to The Nature Conservancy, which transferred the land to the U.S. Fish and Wildlife Service. This …

Water Quality Trends In The Las Vegas Wash Wetlands, F. A. Morris, L. J. Paulson

Publications (WR)

The Las Vegas Wash is a wetlands ecosystem that acts to buffer the effects of wastewater discharges on the receiving waters of Lake Mead. The wash is the terminus for the 4,144 km2 Las Vegas Valley drainage basin, emptying into Las Vegas Bay of Lake Mead (Colorado River). It is in the northern Mojave desert, which receives an average of only 10 cm of rainfall annually. The Las Vegas Wash is technically an artificial wetland supported almost entirely by the perennial flows from sewage treatment plants. These flows contribute an average of 3-7 t of nutrients (nitrogen and phosphorus) and …

Use Of Hydroelectric Dams To Control Evaporation And Salinity In The Colorado River System, Larry J. Paulson

Publications (WR)

The main stem reservoirs on the Colorado River comprise one of the largest and most heavily used freshwater bodies in the nation. These reservoirs (Lake Powell, Lake Mead, Lake Mohave and Lake Havasu) can store up to 53,590,400 acre-feet of water at their maximum capacities. Nonetheless, local water shortages still exist in some areas of the Colorado River Basin. There is also concern that salt concentrations are approaching levels that could severely affect municipal and agricultural uses. Water shortages will become even more acute as demands for water increase with continued urban and agricultural development in the basin. Water conservation …

The Influence Of Lake Powell On The Suspended Sediment-Phosphorus Dynamics Of The Colorado River Inflow To Lake Mead, T. D. Evans, Larry J. Paulson

Publications (WR)

The Colorado River has been successively modified by the construction of several reservoirs, beginning in 1935 with the formation of Lake Mead by Hoover Dam. These reservoirs are located in a chain, and each one has an influence on the nutrient dynamics and productivity of the river and downstream reservoir. Lake Mead derives 98% of its annual inflow from the Colorado River. Historically, the Colorado River inflow was unregulated into Lake Mead. Regulation occurred in 1963, when Lake Powell was impounded by the construction of Glen Canyon Dam, approximately 450 km upstream. The formation of Lake Powell drastically altered the …

Effects Of Wastewater Discharges On Periphyton Growth In Lake Mead, Nevada-Arizona, Marsha Korb Morris

Publications (WR)

A study of the effects of secondary-treated wastewater on periphyton growth in Lake Mead, Nevada-Arizona was conducted from September 1979 to December 1980. Periphyton ash-free dry weight, chlorophyll-a, dominant species composition, and alkaline phosphatase activity were measured on fiberglass substrates. Substrates were incubated for two to four weeks in littoral and limnetic habitats. Physical and chemical variables and phytoplankton chlorophyll-a were measured concurrently.

Transparency increased with increasing distance from the discharge. Secchi depth ranged from 0.75 m at the discharge confluence (station 2) in August, to greater than 20 m at the most distant stations (stations 9 and 10) in …

Charles Lutz Visits Dordt, John Zinkand

Pro Rege

No abstract provided.

Report No 49 - Geographically Restricted Plants Of Southern Western Australia, Barbara L. Rye

Fisheries Research Reports

This publication lists 527 angiosperm species native to southern western Australia whose known geographical ranges are less than 100 kilometres long. A further 128 angiosperms are listed with geographical ranges between 100 and 160 kilometres. No fern or gymnosperm species in the region are known to be geographically restricted.

Apart from the presently unnamed species, a large majority of the rare plants of southern Western Australia are believed to be listed, including 86 of the species that have been gazetted as rare flora.

Less than 40% of the listed species are known to occur on conservation reserves and less than …

Fishery Report No 55 - The Western Rock Lobster Fishery 1961 - 1971, G. R. Morgan, E H. Barker

Fisheries Research Reports

The fishery for the western rock lobster, Panulinus cygnus is one of the most important single fisheries in Australia and one of the major rock lobster fisheries of the world with catches in recent years averaging some 8000 tonnes annually. The history of the commercial fishery extends back to 1944/45 factory when a canning was opened at the Abrolhos Islands (Figure 1) with a view to supplying the Australian armed forces. After the World war, an export market for fresh frozen rock lobster tails was quickly established in the U.S.A. and the industry, sharing in the advantages of postwar reconstruction, …

Fisheries Report No 51 - 'Taiyo Maru 71" Demersal Trawling Cruise In Western Australian Coastal Waters South Of 21 S, July-September, 1979, D. I. Heald, M. H. Walker

Fisheries Research Reports

A Japanese demersal trawler, 'Taiyo Maru 771' was given special permission to conduct exploratory trawling in the period 73.7.79-16.9.79 off the Western Australian coast between 21°S Latitude and 35°30'S Latitude, an area which partly overlapped the fishing grounds for the western rock Lobster. The vessel was required to complete a catch, fishing effort and species composition log book issued by the Commonweath Department of Primary Industry. Two Western Australian Department of Fisheries and Wildlife observers on board monitored fishing operations for the entire duration of the cause and undertook research.

Details of each trawl conducted are given and discussed. Catch …

Fisheries Report No 57 - Exploratory Fishing For Spanish Mackerel In Waters Off Western Australia During The Period June 16 To October 16, 1981, K. Donohue, P. Edsall, J. Robins, R. Tregonning

Fisheries Research Reports

The results of catching Spanish mackerel (Scomberomorus commerson) by gillnet and troll lines during a survey extending from June 16 to October 16 1981 are presented.

The catch rate of mackerel obtained by trolling with six lines was found to be 14.35 times greater than that by gillnet, measuring 0.75 miles in length.

From the results presented, a professional fisherman should be able to assess the economic viability of fishing commercially for Spanish mackerel.

Analysis of biometrial and biological data on fish caught allowed determination of (a) length/weight relationship of (i) Spanish mackerel (ii) wahoo (Acanthocybium solandri); (b) sex ratios …

Fisheries Report No 52 - The Present State Of The Western Australian Fishery For Australian Salmon, Michael H. Walker

Fisheries Research Reports

In 1975, following a number of years of research by the CSIRO Division of Fisheries and Oceanography, it was decided to conduct. a renewed programme cooperatively between CSIRO and W.A. Department of Fisheries and Wildlife. The results of the joint programmes will be presented elsewhere. Meanwhile this paper. describes the Western Australian salmon fishery in 1981 and over the life of the current CSIRO/W.A. salmon research programme i.e. 1975-1981. It considers both the professional and amateur fishery, the disposal of the catch and attempts to discuss any changes in technique, effort, etc. which may have occurred in the period 1975-1981. …

Fisheries Report No 48 - The Western Rock Lobster Fishery 1976 - 1977, G. R. Morgan, E H. Barker

Fisheries Research Reports

The fishery for the western rock lobster Panuldinus cygnus is one of the most important single fisheries in Australia and an important export earner for the State. The fishery is governed by a complex set of regulations which have been reviewed by Bowen (1971) and which are designed to limit the total effort to acceptable levels and to enforce a legal minimum size. It is thus important to constantly monitor the state of the fishery both to ensure that the effort is remaining within the accepted limits and that the regulations are adequately performing their function of maintaining reasonably stable …

Fisheries Report No 46 - The Amateur Fishery For The Western Rock Lobster, Pamela N. Norton

Fisheries Research Reports

A study of the amateur fishery for the western rock Lobster, Paulinus cygnus George, was commenced by the W.A. Marine Research Laboratories in August, 1976, and was concluded in December, 1978. The main aims of this study were to collect and analyse data to give some estimate of the distribution and magnitude of this amateur fishery.

Prior to this survey, the only catch and fishing effort data available was that obtained from the commercial fishery. Data from the amateur fishery were required in order to make a full assessment of the Level of exploitation of the stocks. In addition, 144 …

Fisheries Report No 44 - The Birds Of Pelsart Island Western Australia, Phillip J. Fuller, Andrew A. Burbidge, A. G. Wells

Fisheries Research Reports

Between 1977 and 1981, 58 species of birds were recorded at Pelsart Island. Fifteen sea birds and one land bird were recorded breeding

Pelsart Island is one of the most important sea bird breeding islands in Australia and the World. Birds of special significance which breed there include the Lesser Noddy Anous tenuirostris, the Common Noddy Anous stolidus, the Sooty Tern Sterna fuscata, the Osprey Pandion haliaetus and the White~breasted Sea-eagle Haliaeetus leucogaster. The Lesser Noddy colony disappeared between 1899 and 1907 during a period of intense guano mining. It re-established sometime between 1913 and 1936 and since 1954 it …