Sizes and ages in commercial landings with estimates of growth, mortality and yield per recruit of yellowtail kingfish (Seriola lalandi) from New South Wales, Australia

2004 ◽  
Vol 55 (5) ◽  
pp. 489 ◽  
Author(s):  
John Stewart ◽  
Douglas J. Ferrell ◽  
Bryan van der Walt
Keyword(s):  
Growth Rates ◽  
New South ◽  
New South Wales ◽  
Fork Length ◽  
South Wales ◽  
Current Minimum ◽  
Yellowtail Kingfish ◽  
Seriola Lalandi ◽  
Size At Age ◽  
Yield Per Recruit

The size and age compositions of yellowtail kingfish (Seriola lalandi) were studied in commercial landings in New South Wales, Australia between 1998 and 2000. The fishery was dominated by fish smaller than 65 cm fork length and these fish were estimated to be 2 and 3 year olds. Estimates of growth rates were made using size-at-age data from sectioned otoliths. The oldest yellowtail kingfish found was 21 years and measured 136 cm fork length. There were no differences in the growth rates between regions or between sexes. Yellowtail kingfish grow rapidly and reach their minimum legal length of 60 cm total length at around 2 years of age. These estimates showed that previous studies, which estimated ages using whole otoliths, may have underestimated the ages of older yellowtail kingfish. Total instantaneous mortality rates generated from catch curves ranged between 0.43 and 0.79. Yield per recruit models suggest that the population is currently growth overfished. The information provided is used to discuss the suitability of the current minimum legal length for yellowtail kingfish in New South Wales.

The growth rates of weaned lambs grazing three legume-based pastures during summer

1980 ◽  
Vol 20 (102) ◽  
pp. 9
Author(s):  
ID Sanderson ◽  
JD McFarlane ◽  
WR McManus
Keyword(s):  
Growth Rates ◽  
New South ◽  
New South Wales ◽  
Red Clover ◽  
Experimental Period ◽  
Poor Growth ◽  
Average Growth ◽  
The Poor ◽  
South Wales ◽  
Lamb Growth

An experiment was conducted on the Central Western Slopes of New South Wales with Dorset Horn x Merino lambs to assess their liveweight gains during summer when weaned on to a lucernebased pasture under dryland conditions, and when weaned on to irrigated lucerne and red clover pastures. Lambs grazing irrigated lucerne, irrigated red clover and dryland lucerne had average growth rates of 155, 178 and 124 g day-1/head, respectively, throughout the 106 day experimental period. The poor growth rates of lambs on the dryland lucerne were apparently due mainly to the low digestibility of the dry feed on offer as a result of low rainfall, which also caused feed supply to be limiting during part of the experimental period. Lamb growth and intake data suggest that the diets selected from the red clover were of higher digestibility than those selected from the irrigated lucerne. It was concluded that irrigated red clover and irrigated lucerne provided useful diets for young lambs in this environment, although the growth rates achieved were less than reported elsewhere for these species in cooler climates. Growth rates achieved by lambs grazing dryland lucerne were less satisfactory for prime lamb production.

Hybrid Bermudagrass compared with Kikuyu and common couch in coastal New South Wales. 1. Establishment, dry matter production and persistence

1979 ◽  
Vol 19 (99) ◽  
pp. 437 ◽  
Author(s):  
AC Andrews ◽  
FC Crofts
Keyword(s):  
Growth Rates ◽  
Dry Matter ◽  
Cynodon Dactylon ◽  
New South ◽  
New South Wales ◽  
Sandy Soils ◽  
The Other ◽  
Potential Value ◽  
South Wales ◽  
Matter Production

Four ecotypes of hybrid Bermudagrass (Cynodon dactylon) were compared with common couch (C. dactylon) and kikuyu (Pennisetum clandestinum) at five sites in coastal districts of New South Wales. The sites were Grafton and Coaldale (Lat. 30�S), Mitchells Island (Lat. 32�S) and Richmond and Badgerys Creek (Lat. 34�S). Hybrid Bermudagrass ecotypes 6389 and 692 were established quickly at all sites while ecotypes 71 9 and 632 were satsifactory. Kikuyu was strong at all sites except Grafton but the rate of establishment of common couch was poor. At the frost-free sandy site of Mitchells Island, Bermudagrass ecotypes 719, 692, 6389, and 632 outyielded kikuyu by 75, 65, 65 and 35%, respectively. However, at Grafton and Coaldale, the highest yielding Bermudagrass ecotype, 719, had only 35% higher production than kikuyu. At the frost prone southern sites of Richmond and Badgerys Creek, the annual production of kikuyu was equal to that of ecotypes 719, 6389, 692 and 632. Common couch yields were equal to kikuyu at all sites except at Richmond. At Mitchells Island, the hybrid Bermudagrasses outyielded kikuyu in spring, summer and early autumn but in the late autumn kikuyu had equal and sometimes higher growth rates than the best Bermudagrasses. In winter, the growth of both species was negligible, although kikuyu, unlike the Bermudagrasses, did produce some new shoots at the base of the sward. Data on persistence under grazing were collected from only three of the sites but trends were similar to establishment. Ecotype 6389 had the highest persistence rating of the Bermudagrasses. Kikuyu failed at the poorly drained sandy site of Grafton but remained strong at the other sites. It was concluded that hybrid Bermudagrasses were of potential value for pastures in New South Wales, especially for sites with sandy soils and low frost incidence.

Modelling the effect on stocking rate and lamb production of allowing ewes to graze a dual-purpose wheat crop in southern New South Wales

2014 ◽  
Vol 54 (10) ◽  
pp. 1625 ◽  
Author(s):  
S. R. McGrath ◽  
J. M. Virgona ◽  
M. A. Friend
Keyword(s):  
Growth Rates ◽  
New South ◽  
New South Wales ◽  
Wheat Crop ◽  
Stocking Rate ◽  
Gross Margin ◽  
Dual Purpose ◽  
Mixed Farming ◽  
South Wales ◽  
Gross Margins

Slow pasture growth rates during winter limit the potential gross margins from autumn and early winter lambing in southern New South Wales (NSW) by limiting stocking rates and/or increasing supplementary feed requirements. Dual-purpose crops can reduce the winter feed gap in mixed-farming systems by increasing the available feed in winter. The simulation software AusFarm was used to model a mixed-farming system at Wagga Wagga with Merino ewes joined to terminal sires and grazing lucerne-subterranean clover pasture over a 41-year period. A paddock of dual-purpose wheat was then added to the system, and ewes were allowed to graze the wheat crop when feed on offer reached 850 kg DM/ha and before GS31. Weaned lambs were sold after late August if lamb growth rates fell below 20 g/head.day, mean lamb weight reached 45 kg or production feeding of lambs was required. Lambing in June resulted in the highest median gross margin whether or not ewes were able to graze the wheat crop during winter. Grazing of a dual-purpose wheat crop resulted in greater proportional increases in gross margins as stocking rate was increased, increased lamb production and reduced supplementary feeding costs, and reduced interannual variability in gross margin returns.

Sustainable grazing systems for the Central Tablelands of New South Wales. 3. Animal production response to pasture type and management

2006 ◽  
Vol 46 (4) ◽  
pp. 471 ◽  
Author(s):  
P. J. Holst ◽  
D. F. Stanley ◽  
G. D. Millar ◽  
A. Radburn ◽  
D. L. Michalk ◽  
...  
Keyword(s):  
Growth Rates ◽  
New South ◽  
Perennial Grass ◽  
New South Wales ◽  
Fibre Diameter ◽  
Export Market ◽  
Feed Quality ◽  
South Wales ◽  
Natural Pasture ◽  
Lamb Growth

The main limitations for prime lamb production in the Central Tablelands of New South Wales are low availability of forage early in the growing season (late autumn–early winter) and low nutritive value in the summer. This paper describes the performance of a first-cross lamb breeding enterprise on 4 pasture types and 2 management systems over 4 years for the Central Tablelands region. The pastures studied comprised a traditional unfertilised naturalised pasture, a similar pasture fertilised with superphosphate, a sod-sown fertilised introduced perennial grass pasture and a sod-sown summer growing perennial, chicory (Cichorium intybus L.) pasture. Grazing management involved either continuous grazing or tactical grazing that combined a lower annual stocking rate with an optional summer rest to maintain perennial grass content above 50%. An additional area of chicory pasture was set aside for finishing lambs. Over the experiment stocking rates were increased each year as the pasture became established, with increases ranging from 1.5 ewes/ha for tactically grazed unfertilised natural pasture to 3.6 ewes/ha, for chicory and clover pasture. The feed quality v. quantity problem of summer and autumn was reaffirmed for each pasture type except chicory and the lamb enterprise appeared to be sufficiently adaptable to be promising. Ewes lambed in September and produced satisfactory lamb growth rates (about 280 g/day for twins) on the various pastures until weaning in late December. Thereafter, lamb growth rates declined as the pastures senesced, except chicory, reaffirming the feed quality v. quantity problem in summer and autumn of naturalised and sown grass pastures for producing lamb to heavyweight market specifications. Weaning liveweights (in the range of 32–40 kg) from grass-based pastures were high enough for only about 45% of the lambs to be sold as domestic trade lambs with the remainder as unfinished lambs. In contrast, the chicory and clover finishing pasture produced lamb growth rates of 125 g/day and quality large, lean lambs suitable for the export market. Vegetable matter in the late January shorn wool was insignificant and there was no significant effect of pasture on fleece weight, fibre diameter or staple strength. Position of break in staples of wool from chicory pastures differed from that of the other pasture types and warrants further study on time of shearing. It was concluded that a first cross lamb producing enterprise of suitable genetics was effective in producing trade and store lambs before pasture senescence, but the inclusion of a specialised pasture of summer growing chicory would create greater opportunities. In the unreliable summer rainfall region of the Central Tablelands, the area of chicory pasture needed to maintain lamb growth rates of >125 g/day, estimated from these results, is around 10 lamb/ha of chicory.

The intake and performance of cattle grazing irrigated pastures. 2. Effect of pasture length on growth of steers

1973 ◽  
Vol 13 (64) ◽  
pp. 477
Author(s):  
DW Hennessy
Keyword(s):  
Organic Matter ◽  
Growth Rates ◽  
Dry Matter ◽  
New South ◽  
New South Wales ◽  
Cattle Grazing ◽  
High Moisture ◽  
Moisture Contents ◽  
South Wales ◽  
And Performance

The organic matter intakes (OMI) and liveweight of twenty-four weaner steers grazing either short or long irrigated annual pastures were compared during May to November in 1964 and 1965 at Leeton, New South Wales. The OMI were estimated from determinations of faeces organic matter output using chromic oxide dilution, and of digestibility estimated from a faeces nitrogen-digestibility relationship for pen-fed cattle. Weaners that grazed the short or long pasture did not differ significantly in final liveweights (356 v.361 kg respectively, 1964; 357 v.361 kg, 1965) or OMI (4.99 v.5.42 kg day-1, 1964; 5.78 v.6.06 kg day-1, 1965) although available dry matter was less (P < 0.05) in short than in long pastures in both years. The OMI were commensurate with the 0.6 kg mean daily liveweight gains of weaners, which however were smaller than other reported growth rates, and an unsatisfactory production from the costly pastures. The reasons for the small liveweight gains are unknown but it is suggested that high moisture contents (85 per cent) of pastures restricted intake, or that high clover contents (58 per cent) caused bloating and rumen distension which thereby restricted intake.

Age, Growth of Snoek, Leionura atun (Euphrasen), in South-eastern Australian Waters

1978 ◽  
Vol 29 (4) ◽  
pp. 435 ◽  
Author(s):  
CJ Grant ◽  
TR Cowper ◽  
DD Reid
Keyword(s):  
Growth Rates ◽  
New South ◽  
New South Wales ◽  
Age And Growth ◽  
South Eastern ◽  
South Wales

Investigation of the age and growth of snoek, L. atun, from south-eastern Australian waters indicates differences in growth rates of fish taken in Bass Strait and eastern Tasmania. These findings add support to earlier suggestions, based on other evidence, that there are at least three populations of this species inhabiting, respectively, Bass Strait, eastern Tasmanian, and eastern Victorian and southern New South Wales waters.

Nitrogen fertilizer responses and seasonal production of temperate and warm climate grasses on the Northern Tablelands of New South Wales

1974 ◽  
Vol 14 (68) ◽  
pp. 362 ◽  
Author(s):  
RL Colman ◽  
A Lazenby ◽  
J Grierson
Keyword(s):  
Growth Rates ◽  
New South ◽  
New South Wales ◽  
Maximum Growth ◽  
Moisture Stress ◽  
Nitrogen Recovery ◽  
First Year ◽  
South Wales ◽  
Dry Conditions ◽  
Nitrogen Rates

The seasonal patterns of herbage production and the nitrogen responses by two temperate (Lolium perenne and Phalaris tuberosa) and two tropical grasses (Digitaria macroglossa and Paspalum dilatatum) were compared in the field at Armidale, New South Wales from January 1969 to March 1971 with and without irrigation. Growth and nitrogen recovery of the grasses were affected by temperature, moisture and nitrogen rate. Temperate grasses produced little herbage at mean weekly temperatures below 6�C. Maximum growth rates were measured in October when mean weekly temperatures were approximately 14�C; growth rate declined markedly over summer. Digitaria was the highest yielding species during the first summer but failed to survive in winter. Paspalum was tolerant of winter temperatures as low as -8�C mean weekly minimum; growth commenced when mean weekly temperatures exceeded 13�C and maximum growth occurred in summer when the highest mean weekly temperature was 20�C. Phalaris and Paspalum were very tolerant of dry conditions but Lolium declined in sward density and subsequent productivity. Response to nitrogen was directly related to seasonal conditions. Highest responses were coincident with the highest growth rates and declined as a result of moisture stress and low temperatures. Splitting nitrogen rates into a number of smaller applications had little effect on total herbage yield or distribution of dry matter production compared with a single topdressing. In the first year of the study the per cent nitrogen recovery by the temperate grasses ranged from 72.5 to 81.9 per cent compared with 25.3 (dryland) and 39.4 per cent (irrigated) for Paspalum. Under dry conditions the apparent percentage nitrogen recovery was increased by irrigation but over the first 48 weeks of the experiment there was little difference in the recovery between irrigated and dryland swards of the temperate grasses.

Measuring and predicting the consequences of drought for a range of perennial grasses on the Northern Tablelands of New South Wales

2000 ◽  
Vol 40 (2) ◽  
pp. 285 ◽  
Author(s):  
S. P. Boschma ◽  
J. M. Scott
Keyword(s):  
Growth Rate ◽  
Growth Rates ◽  
New South ◽  
New South Wales ◽  
Perennial Grasses ◽  
Severe Drought ◽  
Plant Mortality ◽  
Wool Growth ◽  
South Wales ◽  
Drought Conditions

An experiment was conducted at Armidale, New South Wales to evaluate the persistence and productivity of 6 perennial grasses under 2 defoliation severities and a range of moisture/drought conditions created using a rain-out shelter. Defoliation was either moderate or severe whilst the moisture/drought conditions imposed included a non-stressed moisture treatment, and seasonal droughts simulated as 40-percentile (40-P) and 10-percentile rainfall (10-P). The treatments were applied over 2 experimental seasons; spring–summer and summer–autumn. A range of measurements was taken including plant mortality, basal area, foliage greenness, herbage mass, growth rate and digestibility. Some of these results were then used as inputs to the GrazFeed decision support system to predict liveweight gain and wool growth rate from pastures growing under such conditions. Plant mortality of over 40% was observed in Dactylis glomerata and Lolium perenne under moderate (40-P) drought conditions during spring–summer. In contrast, under severe drought conditions (10-P), less than 20% of plants died, suggesting that, when combined with defoliation stress, a more common drought can present a greater hazard to plant persistence than a severe drought during spring–summer. Plant mortality was reduced and non-significant when subjected to the summer–autumn drought treatments. Plant growth and predictions of animal productivity varied widely among the species challenged with drought and defoliation stresses. Predicted liveweight gains of weaner sheep under severe drought conditions (10-P) varied between species ranging from 20 to 110 g/day. Under the same conditions, predicted wool growth rates varied between species from 5 to 11 g/wether. day, while pasture growth rates varied from a low of 0 to more than 120 kg DM/ha. day. The animal effects were due largely to differences in herbage mass and the degree to which the grass remained green. These results highlight the importance of maintaining the most productive species in pastures through drought.

Deterministic compartmental model for the eastern king prawn (Penaeus plebejus) fishery in New South Wales

1995 ◽  
Vol 46 (5) ◽  
pp. 793 ◽  
Author(s):  
GNG Gordon ◽  
NL Andrew ◽  
SS Montgomery
Keyword(s):  
Compartmental Model ◽  
New South ◽  
New South Wales ◽  
Eastern Coast ◽  
Migration Patterns ◽  
First Order ◽  
The North ◽  
Estimated Parameters ◽  
South Wales ◽  
Yield Per Recruit

Eastern king prawns (Penaeus plebejus) migrate north from estuaries along the eastern coast of New South Wales and are subject to fishing during this migration. A constant-parameter deterministic compartmental model of the northward migration is described in which the compartments are zones of constant latitudinal width. Assumptions made for each zone are similar to those made for the Baranov catch equation, in which the population decays exponentially through constant instantaneous rates of natural mortality, fishing mortality and emigration. However, in addition to these assumptions, emigration from each zone is assumed to replenish the population in the next zone to the north. This results in the dynamics of the population being described by a system of constant-coefficient linear first-order differential equations. The solutions of this system and of equations for cumulative catch are given in a form that allows the model to be generalized to other migration patterns as a multi- zone analogue of the Baranov catch equation. A discretized form of the model with a restricted parameterization is used to analyse tag-return data from four tag releases. Estimated parameters are used in a yield-per-recruit analysis of prawns recruited to the ocean fishery from Botany Bay.

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