A tagging study on tailor (Pomatomus saltatrix) in Western Australian waters: their movement, exploitation, growth and mortality

1999 ◽  
Vol 50 (7) ◽  
pp. 633 ◽  
Author(s):  
Glen C. Young ◽  
Brent S. Wise ◽  
Suzanne G. Ayvazian
Keyword(s):  
Western Australia ◽  
Loss Rate ◽  
Minimum Length ◽  
Total Catch ◽  
Adult Fish ◽  
Pomatomus Saltatrix ◽  
Commercial Catch ◽  
Marine Areas ◽  
Australian Coastline ◽  
Western Australian

Recreational anglers fishing for tailor (Pomatomus saltatrix) around Perth, Western Australia, have expressed concern over declining catches during the early 1990s. A total of 3949 undersize (below the legal minimum length of 250 mm), 1015 sub-adult and 143 adult tailor were tagged between November 1994 and August 1996 at 24 sites along 1200 km of Western Australian coastline. Undersize tailor were recaptured at lower rates than sub-adult tailor, and were, on average, at liberty for longer periods. Modelling indicates that fishers under-report undersize fish, probably because of the legal minimum length requirement, and that the natural loss rate is higher for undersize than sub-adult fish. The majority of recaptured undersize and sub-adult fish had moved <25 km, remaining in sheltered estuarine and marine areas. In contrast, recaptured undersize and sub-adult tailor that had become adults while tagged displayed behaviour consistent with a northward or offshore winter movement. Comparisons between tag returns and the annual commercial catch of tailor suggests that recreational fishers take the majority of the total catch of tailor in Western Australia. Growth estimates between 0.41 ± 0.19 and 0.44 ± 0.12 mm day −1 suggest that tailor reach legal size in 18–22 months.

Preliminary assessments of stocks of the Western Australian crayfish, Panulirus cygnus George

1966 ◽  
Vol 17 (1) ◽  
pp. 93 ◽  
Author(s):  
BK Bowen ◽  
RG Chittleborough
Keyword(s):  
Western Australia ◽  
Fishing Effort ◽  
Total Catch ◽  
Catch Per Unit Effort ◽  
Stock Size ◽  
Unit Effort ◽  
Exploitation Rate ◽  
Panulirus Cygnus ◽  
Western Australian ◽  
Closed Period

Total catch of Panulirus cygnus in Western Australia rose from 0.6 million lb in 1944-45 to 21.4 million Ib in 1962-63. Fishing effort increased rapidly with the result that the catch per unit effort declined progressively. Effort has been limited by regulation since 1963. From records of catch and effort from specified areas at intervals of one month throughout each season, estimates were made of mortality coefficients (Z1, F, and M1) and catchability coefficient (q). Stock size, recruitment, and exploitation rates were then estimated. As the seasonal catch per unit effort followed the same trend throughout all fishing areas, the detailed results from the selected areas have been applied to the whole fishery. The fishable stock, originally of approximately 140 million lb, had declined to some 35 million lb by 1963. Exploitation rate rose as effort was increased, and then levelled off (generally at above 60%), further increase in fishing effort resulting in a fall in the catchability coefficient rather than a change in the exploitation rate. Because of the high exploitation rate in recent years, the fishable stock available on the grounds at the opening of a season is largely dependent on recruitment (by growth) of juveniles during the preceding closed period. This recruitment has been diminishing from year to year, apparently because of mortality of undersize (pre-recruit) crayfish handled in fishing pots. Provision of escape gaps in all fishing pots is recommended. A sustainable level of catch might be 16,000,000±2,000,0001b per year if recruitment can be stabilized. Some further restriction of fishing effort might be necessary.

Reproductive Periodicity in a Population of Crested Terns, Sterna bergii Lichtenstein in South Australia

1985 ◽  
Vol 12 (1) ◽  
pp. 95 ◽  
Author(s):  
JN Dunlop
Keyword(s):  
Western Australia ◽  
South Australia ◽  
Seabird Species ◽  
Sedentary Population ◽  
Breeding Cycles ◽  
Breeding Condition ◽  
Australian Coastline ◽  
Reproductive Cycles ◽  
Western Australian

Crested terns breeding in the Fremantle area of south-western Australia nest over an 8-month period, from early April to early November. However, laying is markedly bimodal, with subseasons in autumn and spring. Observations of individually marked breeding crested terns indicated a sedentary population utilizing a number of alternative, traditional colony sites all of which were within the study area. Individual crested terns tended to lay in the same part of the season as in the previous year. Colonies made up of terns with similarly phased reproductive cycles formed at different times within the protracted laying period. Individuals completed only one nesting cycle within a season, remaining in breeding condition for approximately 11-13 weeks. Breeding cycles were broadly circannual but potentially sub-annual. Despite superficial similarities at the populational level, this laying pattern differs markedly from that recorded for the silver gull in the same area. The pattern of breeding shown by crested terns therefore provides a second model to explain the double-nesting phenomenon observed in a number of seabird species on the western Australian coastline.

Prediction of Commercial Catches of the Western Rock Lobster Panulirus cygnus

1986 ◽  
Vol 43 (11) ◽  
pp. 2126-2130 ◽  
Author(s):  
B. F. Phillips
Keyword(s):  
Single Species ◽  
Total Catch ◽  
Rock Lobster ◽  
Commercial Catch ◽  
Life History Stages ◽  
Last Stage ◽  
Panulirus Cygnus ◽  
Western Australian ◽  
Term Data

Predictions of the size of the Western Australian commercial catch of the western rock lobster Panulirus cygnus have been successfully made 4 yr ahead. The predictive system, which has operated for 9 yr has been recognized by industry and government as an important tool in the management of Australia's most valuable single-species fishery. The accurate prediction depends on demonstrated relationships between the number of rock lobsters at the puerulus stage of their development (the last stage of its pelagic existence) and the level of recruitment to the fishery, and the total catch of the fishery, 4 yr after settlement. Since 1980, predictions of the catches have been based on settlement data from a single site, Seven Mile Beach, which is near the centre of the distribution of the species. The catches of the fishery from 1961–62 to 1983–84 ranged from 6.8 × 106 kg in 1973–74 to 12.4 × 106 kg in 1982–83. Based on a regression of total catches from 1969 to 1979 on puerulus settlement, and allowing for a trend of increasing catch with time, the total catch is predicted to fall to about 7.72 × 106 kg in 1986–87 because of the low level of puerulus settlement in 1982–83. However, increased settlement in 1983–84 and the highest settlement ever recorded in 1984–85 indicate that catches should increase for the 1987–88 fishing season. Similar relationships between life history stages can be discerned for other crustacean species, provided accurate, long-term data are available.

Factors that contribute to urban–rural gradients in risk of schizophrenia: Comparing Danish and Western Australian registers

2021 ◽  
pp. 000486742110096
Author(s):  
Oleguer Plana-Ripoll ◽  
Patsy Di Prinzio ◽  
John J McGrath ◽  
Preben B Mortensen ◽  
Vera A Morgan
Keyword(s):  
Confidence Interval ◽  
Western Australia ◽  
Urban Areas ◽  
Proportional Hazards ◽  
Cox Proportional Hazards ◽  
Hazard Ratio ◽  
Indigenous Status ◽  
Increased Risk ◽  
The Relationship ◽  
Western Australian

Introduction: An association between schizophrenia and urbanicity has long been observed, with studies in many countries, including several from Denmark, reporting that individuals born/raised in densely populated urban settings have an increased risk of developing schizophrenia compared to those born/raised in rural settings. However, these findings have not been replicated in all studies. In particular, a Western Australian study showed a gradient in the opposite direction which disappeared after adjustment for covariates. Given the different findings for Denmark and Western Australia, our aim was to investigate the relationship between schizophrenia and urbanicity in these two regions to determine which factors may be influencing the relationship. Methods: We used population-based cohorts of children born alive between 1980 and 2001 in Western Australia ( N = 428,784) and Denmark ( N = 1,357,874). Children were categorised according to the level of urbanicity of their mother’s residence at time of birth and followed-up through to 30 June 2015. Linkage to State-based registers provided information on schizophrenia diagnosis and a range of covariates. Rates of being diagnosed with schizophrenia for each category of urbanicity were estimated using Cox proportional hazards models adjusted for covariates. Results: During follow-up, 1618 (0.4%) children in Western Australia and 11,875 (0.9%) children in Denmark were diagnosed with schizophrenia. In Western Australia, those born in the most remote areas did not experience lower rates of schizophrenia than those born in the most urban areas (hazard ratio = 1.02 [95% confidence interval: 0.81, 1.29]), unlike their Danish counterparts (hazard ratio = 0.62 [95% confidence interval: 0.58, 0.66]). However, when the Western Australian cohort was restricted to children of non-Aboriginal Indigenous status, results were consistent with Danish findings (hazard ratio = 0.46 [95% confidence interval: 0.29, 0.72]). Discussion: Our study highlights the potential for disadvantaged subgroups to mask the contribution of urban-related risk factors to risk of schizophrenia and the importance of stratified analysis in such cases.

Life cycle of the western school prawn, Metapenaeus dalli Racek, in a Western Australian estuary

1986 ◽  
Vol 37 (1) ◽  
pp. 95 ◽  
Author(s):  
IC Potter ◽  
JW Penn ◽  
KS Brooker
Keyword(s):  
Life Cycle ◽  
Western Australia ◽  
Sexual Maturity ◽  
Second Year Of Life ◽  
Second Year ◽  
Australian Estuary ◽  
Western Australian

The absence of marine records for M. dalli below latitude 31�S., together with data on gonadal stages and spermatophore deposition on females of this species in the Swan estuary, provide very strong indications that the western school prawn typically breeds in estuarine environments in south-western Australia. The 0 + recruits, which first appeared in samples in February, remained in the estuary during the following months and by November had reached a size suitable for exploitation. At this time they were approaching sexual maturity and were starting to move from the shallows to the deeper waters of the estuary where they remained for their second year of life. In contrast to Australian Penaeus species, M. dalli mates during the intermoult period when the shell is hard rather than immediately after moulting.

scholarly journals On estimating the age composition of the commercial catch of Northeast Arctic cod from a sample of clusters

2003 ◽  
Vol 60 (2) ◽  
pp. 297-303 ◽  
Author(s):  
Aanes Sondre ◽  
Michael Pennington
Keyword(s):  
Age Structure ◽  
Age Distribution ◽  
Significant Loss ◽  
Effective Sample Size ◽  
Commercial Fishing ◽  
Total Catch ◽  
Intracluster Correlation ◽  
Age Composition ◽  
Commercial Catch ◽  
Arctic Cod

Abstract Assessment of Northeast Arctic cod is based on estimates of the commercial catch in numbers at age. The age structure of the catch is estimated by sampling fish from commercial fishing trips. Although it is commonly assumed that a sample of individuals is a random sample from the population, fish sampled from the same trip (i.e. from a “cluster” of fish) tend to be more similar in age than those in the total catch. For Northeast Arctic cod, the intracluster correlation for age is positive, and therefore the effective sample size is much smaller than the number of fish aged. Given the number of fish aged, the precision of the estimated age distribution is rather low, and the number of fish aged from each trip could be reduced from approximately 85 to 20 without a significant loss in precision.

Aspects of reproduction, and morphology of the penis, of Pseudantechinus woolleyae (Marsupialia : Dasyuridae)

2017 ◽  
Vol 65 (6) ◽  
pp. 357 ◽  
Author(s):  
P. A. Woolley
Keyword(s):  
Western Australia ◽  
Arid Regions ◽  
Wide Distribution ◽  
Erectile Tissue ◽  
Australian Museum ◽  
Seasonal Breeder ◽  
Males And Females ◽  
One Year ◽  
Western Australian

Woolley’s Pseudantechinus, P. woolleyae, has remained virtually unstudied in the 30 years since its recognition in 1988 as a species distinct from P. macdonnellensis. It has a wide distribution in arid regions of Western Australia. What little is known of its biology comes largely from studies carried out over the years 1988–91 on one wild-caught female and her offspring, and a few specimens held in the collection of the Western Australian Museum. P. woolleyae is a seasonal breeder and young are born from late July to early October. They mature when ~7 months old. Both males and females are potentially capable of breeding in more than one year. Males have accessory erectile tissue that does not form an appendage on the penis.

The Distribution of Phytophthora cinnamomi Rands at Two Sites in Southern Western Australia and at Durras in South-Eastern New South Wales.

1982 ◽  
Vol 30 (2) ◽  
pp. 139 ◽  
Author(s):  
WM Blowes ◽  
WA Heather ◽  
N Malajczuk ◽  
SR Shea
Keyword(s):  
Western Australia ◽  
Phytophthora Cinnamomi ◽  
New South ◽  
New South Wales ◽  
Native Forest ◽  
Prevention Strategies ◽  
South Eastern ◽  
Isolation Techniques ◽  
South Wales ◽  
Western Australian

Native forest at Durras in south-eastern New South Wales and Jarrahdale in south-western Western Australia was examined for the presence of Phytophthora cinnamomi by two sampling and isolation techniques. With the lupin seeding baiting technique, randomly selected samples of soil and fine roots collected from the New South Wales site yielded P. cinnamomi when baited, while similar baiting of comparable samples from Western Australia failed. Direct plating of samples of upper roots and root collars of recently dead Banksia grandis from Western Australian sites yielded P. cinnamomi, while this organism was not isolated from comparable samples of chlorotic Macrozamia communis collected at the New South Wales site. The results suggest that the form of occurrence of P. cinnamomi and its association with disease in Australia vary in different situations. Viewing each situation independently might ensure the adoption of control/prevention strategies appropriate to all.

scholarly journals Attributes for effective nurse management within the health services of Western Australia, Singapore and Tanzania

2013 ◽  
Vol 37 (2) ◽  
pp. 268 ◽  
Author(s):  
Duncan Boldy ◽  
Phillip Della ◽  
Rene Michael ◽  
Mark Jones ◽  
Shelley Gower
Keyword(s):  
Health Services ◽  
Transactional Leadership ◽  
Western Australia ◽  
Nurse Managers ◽  
Healthcare Management ◽  
Personality Characteristics ◽  
Management Effectiveness ◽  
Cultural Backgrounds ◽  
Beliefs And Values ◽  
Western Australian

Objective. To identify the perceptions of nurse managers in Western Australia, Singapore and Tanzania regarding desirable attributes for effective management of their health services, and to identify and discuss the implications for health-management education provided by Australian universities. Methods. Nurse managers completed a questionnaire covering four key dimensions: personality characteristics, knowledge and learning, skills, and beliefs and values. Each of 75 items were rated as to their effect on management effectiveness, according to a 5-point Likert scale. Results. Skills were considered the most important for management effectiveness by each group. Tanzanian respondents rated knowledge and learning almost as highly, and significantly higher than Western Australian respondents. They also rated personality characteristics and beliefs and values significantly higher than Western Australian respondents. No significant differences were found between Singapore and Western Australia. Conclusions. Participants desired a different relative mix of attributes in their nurse managers, with Western Australian respondents most likely to indicate that transformational leadership contributed most to managerial effectiveness. Tanzanian nurse managers were most likely to advocate transactional leadership, whereas Singaporean nurse managers’ views were located somewhere between. Given that these perceptions are valid, the content and curricula of management-development courses need to be cognisant of the cultural backgrounds of participants. What is known about the topic? Views differ as to the extent to which the criteria for management effectiveness are broadly universal or contingent on culture. This applies to the area of nurse management as it does to healthcare management in general. What does this paper add? It is demonstrated that each of the three quite different countries or states considered identified a distinctive combination of attributes as desirable, with the nurse managers of Western Australia most likely to favour a transformational style of leadership, those from Tanzania a transactional leadership style and those from Singapore somewhere in between. What are the implications for practitioners? Given the country- or state-specific desire for a different relative mix of attributes in their nurse managers, management educators in Australia need to ensure that the content and curricula of their courses are cognisant of the cultural backgrounds of their students. There are also important lessons to be taken on board regarding recruitment of nurses into management positions in terms of each of the four dimensions considered, particularly in terms of desirable personality characteristics and beliefs and values.

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