Validity of using translucent zones of otoliths to age the pilchard Sardinops sagax neopilchardus from Albany, Western Australia

1996 ◽  
Vol 47 (4) ◽  
pp. 617 ◽  
Author(s):  
WJ Fletcher ◽  
SJ Blight
Keyword(s):  
Western Australia ◽  
Age Groups ◽  
Growth Curves ◽  
Relative Number ◽  
Older Individuals ◽  
Commercial Catch ◽  
Monthly Basis ◽  
Lower Accuracy ◽  
Sardinops Sagax ◽  
Catch Rates

Otoliths (sagittae) of the pilchard (Sardinops sagax neopilchardus) from the Albany region of Western Australia were examined on a monthly basis during 1989 to 1991. When read consecutively, with the month of capture known, a clear annual cycle of an increase in marginal increments to October followed by a decline was recorded. This pattern was, however, severely distorted when samples were re-examined after having been jumbled and the month of capture concealed. Younger age groups (≤3) showed evidence of multiple rings being formed annually, but not in all years or individuals, and this was not evident in older individuals (≥4). Agreement between readings was low (43-53%), especially between different readers. Resultant growth curves showed that males grow to a smaller size (L∞ =164, K = 0.805, Φ = 1.03) than females (L∞ = 174, K = 0.584, Φ= 0.95). Agreement between counts of annuli and ages estimated by using otolith weight and length was only 54% for all individuals, but increased to 76% for individuals assigned the same age by different readers. Given the poorer predictions of future catch rates from the relative number of 2-year-olds in the commercial catch using annuli (implying lower accuracy) and increased complexity in preparation, otolith weights will be the method adopted for future ageing.

Continuous Crayfishing Tests: Pelsart Group, Houtman Abrolhos, Western Australia, 1953

1957 ◽  
Vol 8 (4) ◽  
pp. 476 ◽  
Author(s):  
RW George
Keyword(s):  
Western Australia ◽  
Carapace Length ◽  
Long Distance ◽  
Commercial Catch ◽  
Maximum Production ◽  
Catch Rates ◽  
Intensive Fishing

The continuous crayfishing test at the Pelsart Group, Houtman Abrolhos, conducted in 1948, was repeated in 1953. The numbers of crayfish available within the tested area had been reduced from 90 per haul in 1948 to 37 per haul in 1953. There was also a decrease in the commercial catch in 1953 as compared with that of 1948 in the proportion of 90 to 72; and in the catch per man in the proportion 90 to 66. The ratio of the commercial catch in 1950 (the year of maximum production and one of high fishing intensity) to that of 1953 was 90 to 34. In 1953, there were relatively fewer very small and very large crayfish than in 1948. The effects of the 4 years of intensive fishing between 1948 and 1953 on the composition and the numbers of crayfish available at the Pelsart Group are discussed. The period of the test from March 15 to August 26 was divided into three catch phases, characterized by changes in the catch rates. Except for three long-distance movements of tagged crayfish, movements were limited to a distance of approximately 2 miles. Mating commenced on July 1 and by the end of August the majority of mature females were mated. Spawning commenced on August 22. Few females below a carapace length of 2.9 in. were mated.

Biology and fishery of pilchard, Sardinops sagax (Clupeidae), within a large south-eastern Australian bay

1999 ◽  
Vol 50 (1) ◽  
pp. 43 ◽  
Author(s):  
Francisco J. Neira ◽  
Miriana I. Sporcic ◽  
Andrew R. Longmore
Keyword(s):  
Sexual Maturity ◽  
Multivariate Time Series ◽  
Fork Length ◽  
Early Summer ◽  
Length Frequency ◽  
Commercial Catch ◽  
Shallow Marine ◽  
Sardinops Sagax ◽  
Catch Rates ◽  
Marine Embayment

Length–frequency and maturity data of pilchards (Sardinops sagax) are described from monthly purse-seine commercial catch samples obtained in Port Phillip Bay (Victoria) between December 1994 and January 1997. These data, together with findings of a 12-month ichthyoplankton bay survey from September 1995 to August 1996, were used to determine the size at which pilchards recruit to the bay fishery and whether they spawn within this system. Monthly pilchard catch rates between January 1990 and June 1996 are also described and analysed in terms of environmental variables during that period. Results show that pilchards do not generally attain sexual maturity or spawn within the bay but use it as a nursery area, entering this system mostly as 0+ to 1+ year-o ld juveniles (4–12 cm fork length, FL) in late spring–early summer and returning to sea the following winter. This migration is supported by the marked seasonality in catch rates, which each year peak in March–May and are lowest in August–October. The seasonality was adequately explained by temperature lagged 2 months in a multivariate time-series model. Port Phillip Bay appears to be the only semi-enclosed, shallow marine embayment in temperate Australia that supports a substantial pilchard fishery that, in addition, is based predominantly on juveniles.

Catching characteristics of four fish-trap types on the North West Shelf of Australia

1991 ◽  
Vol 42 (4) ◽  
pp. 369 ◽  
Author(s):  
AW Whitelaw ◽  
KJ Sainsbury ◽  
GJ Dews ◽  
RA Campbell
Keyword(s):  
Species Composition ◽  
Western Australia ◽  
Commercial Catch ◽  
North West ◽  
Fish Trap ◽  
The North ◽  
Significant Difference ◽  
Trap Fishery ◽  
Catch Rates ◽  
North Western

Commercial catch rates for the North West Shelf trap fishery, at up to 10 kg trap-1 h-1, are considerably greater than those reported for similar trap fisheries elsewhere. Two fish-trapping experiments were conducted off Lowendal Island (north-western Australia) to study the catch rates of four trap types (O-, S- and Z-shaped and rotational) and two bait types (pilchard, Sardinops neopilchardus, and emperor, Lethrinus choerorynchus) over various soak times (ranging from 1 to 24 h). Total catches varied significantly with soak time. Catches increased rapidly for the first 3 h, levelled off, and then decreased steadily to 16 h; there was a slight increase at 24 h. The species composition of the catch did not vary significantly with soak time. There was no significant difference in catch rates between trap types. The traps did not appear to cause fish to die by being confined in the traps for extended periods. A fairly large amount of suitable bait (about 4 kg) was necessary for effective trapping of fish. The catch rates of the pilchard bait were significantly higher than those of the emperor bait. Over extended soak times (more than 3 h), pilchard bait was lost at a rate of about 6% h-1. whereas there was no detectable loss of emperor bait.

scholarly journals Parasitic fauna of Eurasian beavers (Castor fiber) in Sweden (1997–1998)

2021 ◽  
Vol 63 (1) ◽  
Author(s):  
Per-Arne Åhlen ◽  
Göran Sjöberg ◽  
Margareta Stéen
Keyword(s):  
Age Groups ◽  
Ecological Factors ◽  
Parasite Fauna ◽  
Castor Fiber ◽  
Older Individuals ◽  
Parasitic Fauna ◽  
Eurasian Beaver ◽  
Norwegian Population ◽  
Stichorchis Subtriquetrus ◽  
One Year

Abstract Background The parasitic fauna of beavers (Castor fiber and C. canadensis) has been well studied in many parts of their respective areas of distribution. In Scandinavia there have, however, been limited investigations conducted on the parasites of beavers in recent times. The present study is the first quantitative survey of parasites on beavers living in Sweden and elsewhere in Scandinavia. We investigated the parasitic fauna of the Eurasian beaver (C. fiber) in a North–South gradient in Sweden. The aim of the study was to investigate parasite distribution and prevalence in particular, related to average yearly air temperature and different age groups of beavers. A total of 30 beavers were sampled at eight localities, spanning a 720 km North–South gradient during the springs of 1997 and 1998. Results Five parasite taxa were identified. Four of these were present in all of the examined beavers, Stichorchis subtriquetrus (trematode), Travassosius rufus (nematode), Platypsyllus castoris (coleopteran), and Schizocarpus spp. (arachnid). A higher number of new infections of S. subtriquetrus, and more adults of T. rufus, were seen in beavers in southern Sweden where temperatures are higher. One-year old beavers had a higher infestation of S. subtriquetrus, but not of T. rufus, than older individuals. Conclusions The parasite fauna of Swedish beavers mirrored the impoverished parasite fauna of the original Norwegian population, and the high prevalence of parasites could be due to low major histocompatibility complex (MHC) polymorphism. Young beavers had a higher load of trematodes, probably depending on behavioural and ecological factors. Warmer temperatures in southern localities likely contributed to increased endoparasite loads.

Growth and spatiotemporal distribution of juvenile shortfin mako (Isurus oxyrinchus) in the western and central North Pacific

2015 ◽  
Vol 66 (12) ◽  
pp. 1176 ◽  
Author(s):  
M. Kai ◽  
K. Shiozaki ◽  
S. Ohshimo ◽  
K. Yokawa
Keyword(s):  
North Pacific ◽  
Linear Models ◽  
North Pacific Ocean ◽  
Age Groups ◽  
Growth Curves ◽  
Growth Function ◽  
Gaussian Mixture ◽  
Isurus Oxyrinchus ◽  
Shortfin Mako ◽  
Central North Pacific

This paper presents an estimation of growth curves and spatiotemporal distributions of juvenile shortfin mako shark (Isurus oxyrinchus) in the western and central North Pacific Ocean using port sampling data collected from 2005 to 2013. The monthly length compositions show a clear transition of three modes in the size range of smaller than 150-cm precaudal length (PCL), which were believed to represent the growth of age-0 to age-2 classes, and they were then decomposed into age groups by fitting a Gaussian mixture distribution. Simulation data of lengths at monthly ages were generated from the mean and standard deviation of each distribution, and fit with a von Bertalanffy growth function. Parameters of the estimated growth curves for males and females were 274.4 and 239.4cm PCL for the asymptotic length and 0.19 and 0.25 year–1 for the growth coefficient indicating apparently faster growth than previously reported. Generalised linear models were applied to age-0 to explore the seasonal changes of PCL by area. They were born during late autumn and winter off the coast of north-eastern Japan, an area known to have relatively high productivity compared with other pelagic areas, and gradually expanded their habitat eastward and northward with the seasons as they grew.

scholarly journals Female reproductive biology and spawning periodicity of two species of king prawns, Penaeus longistylus Kubo and Penaeus latisulcatus Kishinouye, form Queensland's East Coast Fishery

1988 ◽  
Vol 39 (6) ◽  
pp. 729 ◽  
Author(s):  
AJ Courtney ◽  
MCL Dredge
Keyword(s):  
Egg Production ◽  
East Coast ◽  
Sea Water ◽  
Coastal Region ◽  
Ovary Development ◽  
Commercial Catch ◽  
Ovary Weight ◽  
Species Population ◽  
Spawning Periodicity ◽  
Catch Rates

In the coastal region of central Queensland female red-spot king prawns, P. longistylus, and the western or blue-leg king prawns, P. latisulcatus, had high mean ovary weights and high proportions of advanced ovary development during the winter months of July and August of 1985 and 1986. On the basis of insemination, both species began copulating at the size of 26-27 mm CL, but P. longistylus matured and spawned at a smaller size than P. latisulcatus. Abundance of P. longistylus was generally three to four times greater than that of P. latisulcatus but the latter was subject to greater variation in abundance. Low mean ovary weight and low proportions of females with advanced ovaries were associated with the maximum mean bottom sea-water temperature (28.5�C) for both species. Population fecundity indices indicated that peaks in yolk or egg production (a) displayed a similar pattern for both species, (b) varied in timing from year to year for both species and (c) were strongly influenced by abundance. Generally, sample estimates of abundance and commercial catch rates (CPUE) showed similar trends. Differences between the two may have been due to changes in targeted commercial effort in this multi-species fishery.

scholarly journals Age-related mortality in 61,993 confirmed COVID-19 cases over three epidemic waves in Aragon, Spain. Implications for vaccination programmes

PLoS ONE ◽  
2021 ◽  
Vol 16 (12) ◽  
pp. e0261061
Author(s):  
Diego Casas-Deza ◽  
Vanesa Bernal-Monterde ◽  
Angel Nicolás Aranda-Alonso ◽  
Enrique Montil-Miguel ◽  
Ana Belen Julián-Gomara ◽  
...  
Keyword(s):  
Age Groups ◽  
Case Fatality ◽  
The Elderly ◽  
Progressive Increase ◽  
University Hospital ◽  
Rapid Progression ◽  
Targeted Prevention ◽  
Older Individuals ◽  
Prevention Measures ◽  
Age Related

Background Risk for severe COVID-19 increases with age. Different vaccination strategies are currently being considered, including those aimed at slowing down transmission and those aimed at providing direct protection to those most at risk. Methods The objectives of the current study were i) to assess age-related incidence and survival between PCR-diagnosed COVID-19 cases (n = 61,993) in the Autonomous Community of Aragon from March to November 2020, and ii) to characterize age differences regarding the course of the disease in hospitalized patients in a tertiary university hospital. Results We found a similar incidence of COVID-19 in individuals between 10 and 79 years. Incidence increased in those over 80 years possibly because of the elevated transmission within the nursing homes. We observed a profound disparity among age groups; case fatality rates (CFRs) were near 0 in cases younger than 39 years throughout different waves. In contrast, there was an age-dependent and progressive increase in the CFRs, especially during the first pandemic wave. SARS-CoV-2 infection caused a more severe and rapid progression in older patients. The elderly required faster hospitalization, presented more serious symptoms on admission, and had a worse clinical course. Hospitalized older individuals, even without comorbidities, had an increased mortality risk directly associated with their age. Lastly, the existence of comorbidities dramatically increased the CFRs in the elderly, especially in males. Conclusion The elevated incidence of COVID-19 and the vulnerability of the elderly call for their prioritization in vaccination and targeted prevention measures specifically focused on this aged population.

scholarly journals SARS-CoV-2 transmission across age groups in France and implications for control

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Cécile Tran Kiem ◽  
Paolo Bosetti ◽  
Juliette Paireau ◽  
Pascal Crépey ◽  
Henrik Salje ◽  
...  
Keyword(s):  
Young Adults ◽  
Age Groups ◽  
Deep Understanding ◽  
Transmission Dynamics ◽  
Age Group ◽  
Older Individuals ◽  
Targeted Intervention ◽  
Social Distancing ◽  
Intervention Measures ◽  
Better Than

AbstractThe shielding of older individuals has been proposed to limit COVID-19 hospitalizations while relaxing general social distancing in the absence of vaccines. Evaluating such approaches requires a deep understanding of transmission dynamics across ages. Here, we use detailed age-specific case and hospitalization data to model the rebound in the French epidemic in summer 2020, characterize age-specific transmission dynamics and critically evaluate different age-targeted intervention measures in the absence of vaccines. We find that while the rebound started in young adults, it reached individuals aged ≥80 y.o. after 4 weeks, despite substantial contact reductions, indicating substantial transmission flows across ages. We derive the contribution of each age group to transmission. While shielding older individuals reduces mortality, it is insufficient to allow major relaxations of social distancing. When the epidemic remains manageable (R close to 1), targeting those most contributing to transmission is better than shielding at-risk individuals. Pandemic control requires an effort from all age groups.

scholarly journals The problem of pertussis in some regions of the world

2019 ◽  
Vol 9 (2) ◽  
pp. 354-362 ◽  
Author(s):  
A. A Basov ◽  
O. V Tsvirkun ◽  
A. G Gerasimova ◽  
A. K Zekoreeva
Keyword(s):  
Molecular Genetic ◽  
Age Groups ◽  
Immunization Coverage ◽  
Cell Vaccine ◽  
Laboratory Diagnostics ◽  
Immunization Schedule ◽  
Older Individuals ◽  
Pertussis Infection ◽  
Whole Cell ◽  
National Immunization

Pertussis infection remains a high-priority issue both for Russian health care and abroad. A rise of pertussis incidence in various human age groups instigates a search for new ways to fight this infection and improve methods for its laboratory diagnostics. By taking into consideration a short-term effect induced by acellular and whole-cell vaccines, a feasibility of introducing the second or even the third pertussis revaccination is vigorously debated. Objective of the study was to analyze the experience and effectiveness of acellular pertussis vaccines in countries, which use the second and third pertussis revaccination in the National Immunization Schedule in order to have an insight into adjusting strategy and tactics of pertussis immunization In Russia. Analyzing pertussis prevalence demonstrated that despite a wide immunization coverage pertussis incidence in the last years (2008–2015) was increased in a large number of countries in the European region, as well as inAustralia,CanadaandUSA. However, the reasons for elevated pertussis incidence have not been clarified yet. On one hand, it may be accounted for by low vaccination coverage in adolescents and adults; weakened immune protection after vaccination; genetic changes in Bordetella pertussis; shortened durability of protective immunity in children vaccinated with acellular vs. whole-cell vaccine; improved monitoring and morbidity reporting, as well as improved laboratory diagnostics due to shifting from serological and bacteriological to molecular genetic assays. In an attempt to solve this issue, researchers from several countries collaborate to discuss and develop a strategy to reduce pertussis incidence. ForRussia, the most important is to empower and/or improve existing infant immunization strategy in order to provide wide coverage with the four dose pertussis vaccine for decreasing the risk of pertussis morbidity and mortality. It is worth noting the “cocoon” strategy given the high risk of pertussis infection in children of the first months of life. We believe that forRussiait is worth investigating an opportunity of using children 2–3 months of life an acellular vaccine as the first vaccination, which is expected to increase the coverage of this cohort and allow to increase proportion of children who might complete vaccination by 5 months of age. At the same time, more reasonable might be to preserve a number of age groups for pertussis vaccination in the current National Immunization Schedule, as expanding age limits for vaccination might put a risk at increasing pertussis morbidity in older individuals, which could be hard to diagnose. 

scholarly journals Trend and Factors Associated with Repeat Computed Tomography Examinations in Tertiary Hospitals: Linked Health Administrative Data in Western Australia

2020 ◽  
Vol 5 (5) ◽  
Author(s):  
Ninh Ha
Keyword(s):  
Ct Scan ◽  
Western Australia ◽  
Age Groups ◽  
Ct Scanning ◽  
Major Surgery ◽  
Factors Associated ◽  
Inappropriate Use ◽  
Tertiary Hospitals ◽  
Picture Archiving And Communication ◽  
Hospital Morbidity

IntroductionComputed tomography (CT) has become an essential part of clinical practice. However, repeat CT scans has raised a concern about unnecessary exposure to ionising radiation and waste of health care resource. While substantial effort is underway to reduce inappropriate use of diagnostic imaging tests including CT, little evidence of any change in repeat CT use and its associated factors. Objectives and ApproachThis study aimed to measure trend in repeat CT use and identify factors associated with repeat CT use in tertiary hospitals in Western Australia (WA). This study used WA linked administrative records from hospital morbidity, emergency department presentations, and picture archiving and communication system datasets to capture all tertiary hospitalisations and number of CT use during the admission from 2003 to 2015. Multivariate logistic regression was used to examine trend and determine characteristics associated with repeat CT, for admissions with and without major surgery during hospitalisation. ResultsAmong 303,439 admissions with CT scan 11.9% had repeat CT scan in the same anatomic areas. While the probability of repeat CT among admission with surgery remained unchanged over the study period, its counterpart significantly reduced about 4% per year. Regardless of surgical status, repeat CT scanning was significantly lower among females, Indigenous and older age groups but higher among people living in rural and remote areas. We found that admissions for circulatory conditions, injuries, cancer or multimorbidity had significantly higher probability of having repeat CT. Conclusion / ImplicationsThis study indicates that clinical factors such as cancer, injury and multimorbidity are factors contributing to repeat CT. A reduction of repeat CT over the study period among admissions without surgical procedure suggests a potential reduction of unnecessary CT scan, although further study is needed to fully capture whether this is an actual change in practice.

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