Role of the crayfish Cherax destructor clark as food for trout in Lake Eucumbene, New South Wales

1983 ◽  
Vol 34 (3) ◽  
pp. 407 ◽  
Author(s):  
RA Faragher
Keyword(s):  
Rainbow Trout ◽  
Brown Trout ◽  
Salmo Trutta ◽  
New South ◽  
New South Wales ◽  
Water Levels ◽  
Size Analysis ◽  
Fish Length ◽  
Freshwater Crayfish ◽  
South Wales

The freshwater crayfish C. destructor was a major dietary item for brown trout, Salmo trutta L., and rainbow trout, S. gairdneri Richardson, in Lake Eucumbene, New South Wales. The incidence of crayfish in the diet increased, particularly in brown trout, over the period 1972-1977. The proportion of the trout's diet comprising C. destructor increased with length of brown trout but not with length of rainbow trout. The size of crayfish ingested was postively correlated with fish length for both species of trout, although rainbow trout tended to ingest smaller crayfish than brown trout of equivalent size. Analysis of the crayfish's diet revealed predominantly plant material. Spawning by the crayfish was apparently confined to the period December-April. The abundance of C. destructor in Lake Eucumbene was apparently low until about 1970 but increased between 1972-1977. A decline in the average size of brown and rainbow trout in the angler catch occurred from 1959-1960 until 1977-1978. Hypotheses are suggested for the increase of the crayfish population since impoundment of the lake (1957). Factors considered include predation by trout and the biology of the crayfish, particularly related to its occurrence in this lake, which has fluctuating water levels and a short season suitable for growth and spawning.

Repeat Homing of Brown Trout (Salmo trutta) in Lake Eucumbene, New South Wales, Australia

1977 ◽  
Vol 34 (8) ◽  
pp. 1085-1094 ◽  
Author(s):  
R. D. J. Tilzey
Keyword(s):  
Rainbow Trout ◽  
Brown Trout ◽  
Salmo Trutta ◽  
New South ◽  
Tag Loss ◽  
Trout Population ◽  
South Wales ◽  
High Incidence ◽  
Brown Trout Salmo Trutta ◽  
External Form

Spawning runs of lentic-dwelling brown trout (Salmo trutta) and rainbow trout (S. gairdneri) in Swamp Creek, an inlet of Lake Eucumbene, were studied for 4 consecutive yr, and 3517 browns and 415 rainbows were tagged during 1968–70. A further 240 browns and 229 rainbows were marked in other inlets. Recaptures of marked browns in 1969 and 1970 showed a high incidence of repeat homing, up to 25.7 and 10.6% returning after 12 and 24 mo, respectively. Few rainbow trout homed. Tag loss and the mortality and maturation of marked browns were estimated and percentage homing and straying in 1969, 1970 and 1971 was calculated. High percentage homing [Formula: see text] in 1969–70 and the variance in external form in the lentic population suggested some genetic isolation within the brown trout population. Homing ability was not influenced by fish age. Percentage homing fell markedly in 1971 after the removal of nearly all resident brown trout from Swamp Creek and suggested racially distinct stream trout populations to be an important navigational cue to homing brown trout. Key words: repeat homing, Salmo trutta, homing frequency, navigation, racial cue, Australia

Comparative exploitation exploitation by recreational anglers of brown trout, Salmo trutta L., and rainbow trout, Oncorhynchus mykiss (Walbaum), in Lake Eucumbene, New South Wales

1992 ◽  
Vol 43 (4) ◽  
pp. 835 ◽  
Author(s):  
RA Faragher ◽  
GNG Gordon
Keyword(s):  
Rainbow Trout ◽  
Confidence Interval ◽  
Brown Trout ◽  
New South ◽  
New South Wales ◽  
Likelihood Method ◽  
Linear Regression Method ◽  
Tag Loss ◽  
South Wales ◽  
Significant Difference

Exploitation rates of syrnpatric brown trout and rainbow trout in Lake Eucumbene, New South Wales, were estimated from a tagging study. Tag returns were analysed by applying a non-linear regression method. Tag loss was estimated from a concurrent double tagging study using a maximum likelihood method. No significant difference at the 5% level was found between the rates of tag loss of the two species. The annual exploitation rate for rainbow trout was 26.7% (95% confidence interval 24.2- 29.2%) and was significantly less for brown trout, 8.8% (95% confidence interval 4.2-13.5%).

Diet and growth of rainbow trout, Salmo gairdneri Richardson, in two streams on the New England Tableland, New South Wales

1981 ◽  
Vol 32 (6) ◽  
pp. 967 ◽  
Author(s):  
RWJ Pidgeon
Keyword(s):  
Rainbow Trout ◽  
New England ◽  
New South ◽  
New South Wales ◽  
Rank Correlation ◽  
Dry Weight ◽  
Fish Growth ◽  
Salmo Gairdneri ◽  
Fish Size ◽  
South Wales

The diets and growth rates of rainbow trout in the Wollomombi and Guy Fawkes Rivers in northern New South Wales were examined. The growth rate of trout in the Wollomombi River was much higher than that of fish in the Guy Fawkes River. Spearman rank correlation coefficients indicated that stream type was more important than fish size in determining the composition of the diet of the trout. Benthic invertebrates formed the largest component of the diet in both streams: 66.0 and 63.0% of ash-free dry weight (AFDW) in the Wollomombi River and the Guy Fawkes River, respectively. Trout in the Wollomombi River consumed more nektonic prey (33.3% of AFDW) than fish in the Guy Fawkes River (3.7% of AFDW). In contrast, surface food (aquatic imagines and terrestrial insects) made up a much higher proportion of the diet of trout in the Guy Fawkes River (33.9% of AFDW) than in the Wollomombi River (0.6% of AFDW). Crayfish were a major component of the diet (in terms of AFDW) in both streams, their proportions increasing with fish size. The significance of crayfish in relation to fish growth is discussed.

Observations on interactions between indigenous Galaxiidae and introduced Salmonidae in the Lake Eucumbene catchment, New South Wales

1976 ◽  
Vol 27 (4) ◽  
pp. 551 ◽  
Author(s):  
RDJ Tilzey
Keyword(s):  
Population Structure ◽  
Catchment Area ◽  
Salmo Trutta ◽  
Historical Data ◽  
New South ◽  
New South Wales ◽  
Fish Fauna ◽  
South Wales ◽  
The One ◽  
Natural Barrier

The fish fauna of all major streams within the Lake Eucumbene catchment in south-eastern New South Wales was sampled by electrofishing or poisoning with rotenone. Galaxias coxii was found in only four, and G. olidus in only one other of the 27 streams sampled whereas the introduced salmonids (Salmo trutta or S. gairdneri, or both) occurred in all but the stream containing G. olidus. Values for galaxiid biomass were low in comparison with those for trout where both occurred together. Sampling in 1971 and 1974 in the one stream observed in 1971 to contain only G. olidus spanned an invasion by S. gairdneri and by 1974 the galaxiid species had completely disappeared below a natural barrier to trout, but above this barrier the biomass and population structure of G. olidus had not changed greatly compared to the 1971 values. This indicated that the presence of S. gairdneri was the sole environmental factor causing galaxiid disappearance below the barrier. Historical data for the catchment area suggested that the introduction and subsequent success of trout are primarily responsible for the present, much fragmented galaxiid distribution.

No evidence for seasonality in the ectoparasitic fauna of slimy mackerel, Scomber australasicus

1993 ◽  
Vol 44 (5) ◽  
pp. 709 ◽  
Author(s):  
KML Perera
Keyword(s):  
Seasonal Variation ◽  
New South ◽  
New South Wales ◽  
Fish Length ◽  
South Wales ◽  
Trypanorhynch Cestode

Fifteen (or sixteen) species of ectoparasites-6 monogeneans, 4 (or 5) trematodes, 2 copepods, 1 isopod, 1 cestode, and unidentified cysts -were collected from 428 Scomber australasicus individuals caught at Eden, New South Wales, Australia, between November 1988 and June 1992. Neither common nor rare parasites of slimy mackerel showed seasonal variation in abundance or prevalence. Only the copepod Brachiella magna occurred more frequently on larger (older) fish than smaller (younger fish). Two monogeneans (Kuhnia scombri, Pseudokuhnia minor), 2 didymozoids, and unidentified cysts occurred more frequently on smaller than larger fish. The intensities of the remaining monogeneans (Kuhnia scombercolias, Kuhnia sprostonae and Grubea australis), 1 didymozoid, 1 copepod (Peniculus sp.), the isopod (Ceratothoa imbricata) and a trypanorhynch cestode were not significantly correlated with fish length.

Studies on Age, Growth, and Life History of the Pilchard, Sardinops neopilchardus (Steindachner), in Southern and Western Australia

1950 ◽  
Vol 1 (2) ◽  
pp. 221 ◽  
Author(s):  
JM Blackburn
Keyword(s):  
Growth Rate ◽  
Western Australia ◽  
New South ◽  
New South Wales ◽  
South Australia ◽  
The Body ◽  
Fish Length ◽  
Linear Type ◽  
Spawning Period ◽  
South Wales

The biology of the unexploited Australian pilchard, Sardinops neopilchardus (Steindachner), was studied from a limited material available from Victorian, Tasmanian, South Australian, and Western Australian waters. This completes the preliminary study of the species over almost the whole of its sub-continental range. In Victorian waters, the surface shoaling season is spring and summer, in South Australia, summer and autumn, and in southern Western Australia, autumn and winter; these are the spawning seasons for the respective areas. In New South Wales and Queensland waters, the shoaling season is autumn to spring, which is again a spawning period. The situation in Tasmania, where the species is rare, is probably similar to that in Victoria. On the west coast of Australia, where the species extends northward to the Tropic of Capricorn (as it also does in the east) the seasonal distribution is not clear. In all these areas pilchard occurrences are virtually limited to the bay and neritic waters. Victorian pilchards attain mean standard lengths of about 8.0, 10.5, 12.5, 14.0, and 15.5 cm. at the ages of one, two, three, four, and five years respectively. This growth rate is considerably lower than that in New South Wales. In southern Western Australia the growth rate is intermediate between the other two, but in South Australia it was not established. The average size of pilchards in the seasonal shoals appears to be greater in Western Australia than elsewhere, but no fish over 19.5 cm. standard length (9.0 in. total length) has been encountered in any of the current Australian investigations. Sexual maturity occurs earlier in Victoria than in New South Wales, sometimes at one year of age. The ring pattern of Australian pilchard scales is complex, involving yearly, spawning, and secondary rings. A hypothesis to account for the formation of spawning rings is outlined, and an earlier hypothesis relating to yearly rings is abandoned. Secondary rings occur on most scales from the same fish. In all waters the season of ring formation coincides with that of surface availability of fish, but in Victoria it is also the growing season, which makes age determination particularly difficult. The fish-length/scale-length relationship for Victorian material is of the same linear type as for New South Wales, but there are differences in the size of scales taken from the same area of the body. The possible influences of distribution, size, and condition of fish on future economic exploitation are discussed.

Breeding Behaviour and Ecology of the Australian Pelican, Pelecanus Conspicillatus, in New South Wales.

1977 ◽  
Vol 4 (1) ◽  
pp. 37 ◽  
Author(s):  
WJM Vestjens
Keyword(s):  
New South ◽  
New South Wales ◽  
Perca Fluviatilis ◽  
Freshwater Crayfish ◽  
Goldfish Carassius Auratus ◽  
Cherax Destructor ◽  
South Wales ◽  
Perch Perca Fluviatilis ◽  
Competition For Food ◽  
A Minor

Australian pelicans (Pelecanus conspicillatus) were studied in colonies at 2 lakes in New South Wales. Adults regurgitated food for the young. Those up to 2 weeks old took liquid food from inside the tip of the adult's upper beak. Older ones took solid food from the adult's gullet, to age of about 3.5 months. After being fed, the young had convulsions lasting about 1 min; that did not happen after a second feeding immediately after the convulsion. Where there were 2 young of different sizes, only the larger convulsed, and sometimes the smaller was prevented from feeding and died of starvation. The survivor continued to have convulsions after feeding, as did single young, when there was no competition for food. Food was mainly fish; the most abundant fish was goldfish (Carassius auratus); a minor item was perch (Perca fluviatilis). Fish were 60 to 247 mm long and weighed 17 to 320 g. Crustaceans were less important and included freshwater crayfish (Cherax destructor) and shrimp (Macrobrachius sp.).

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