Catchability of the southern rock lobster Jasus edwardsii. I. Effects of sex, season and catch history

2002 ◽  
Vol 53 (8) ◽  
pp. 1143 ◽  
Author(s):  
P. E. Ziegler ◽  
S. D. Frusher ◽  
C. R. Johnson ◽  
C. Gardner
Keyword(s):  
Carapace Length ◽  
Early Summer ◽  
Rock Lobster ◽  
Marked Contrast ◽  
Density Estimates ◽  
Male And Female ◽  
Jasus Edwardsii ◽  
Males And Females ◽  
Catch Rates ◽  
Trap Catches

Seasonal variation in catchability of the southern rock lobster Jasus edwardsii, was estimated in a scientific reserve in south-east Tasmania by comparing estimates of lobster density based on direct visual observations underwater with concomitant estimates from trapping surveys. Underwater density estimates of undersized and legal-sized male and female lobsters >80 mm carapace length, did not change significantly over the 14-month study period, with the exception of undersized males (≤110 mm carapace length). Sex ratios remained constant at approximately 1 : 1. In marked contrast, catch rates of males and females and the sex ratio of trapped lobsters varied strongly with season, implying that catchability varies seasonally and with sex. Catchability of males and females was highest in early summer and lowest in winter. Impact of capture on subsequent catchability appeared to be weak, since the ratios of tagged animals in the population observed underwater generally reflected recapture rates of tagged animals in trap catches. Recapture rates increased with size and were higher for medium-sized and large males than for similar-sized females. However, for each particular sex-size group, recapture rates remained relatively constant throughout the study period.

The influence of weather and time of day on trap catches of males and females of Lucilia cuprina (Wiedemann) (Diptera: Calliphoridae)

1985 ◽  
Vol 75 (2) ◽  
pp. 315-320 ◽  
Author(s):  
W. G. Vogt ◽  
T. L. Woodburn ◽  
R. Morton ◽  
B. A. Ellem
Keyword(s):  
Early Morning ◽  
Time Of Day ◽  
Lucilia Cuprina ◽  
Male And Female ◽  
Late Afternoon ◽  
Four Seasons ◽  
Baited Traps ◽  
Males And Females ◽  
Catch Rates ◽  
Trap Catches

AbstractDifferences in responses of males and females of Lucilia cuprina (Wiedemann) to carrion-baited traps were examined in Australia in relation to time of day, temperature, wind speed, relative humidity and solar radiation. The differences were small compared with responses obtained for the combined sexes (total catch), but the results were inconsistent over the four seasons of trapping. The seasons with most data (1975–1976 and 1981–1982) gave reasonably consistent results. Seasonal differences, although significant, were small enough to neglect for the purpose of standardizing trap catches. Time-of-day effects were also unimportant, except that males tended to be less active than females during the early morning (dawn-0900 h) and more active than females during the late afternoon (1500 h-dusk). Separate models are presented for standardization of male and female catch rates; the estimates differ from those obtained from total catches, but the differences are small compared to the observed day-to-day variation in catch rates.

Feeding technique, critical size and size preference of Jasus edwardsii fed cultured and wild mussels

1998 ◽  
Vol 49 (2) ◽  
pp. 151 ◽  
Author(s):  
Philip J. James ◽  
Lennard J. Tong
Keyword(s):  
Shell Length ◽  
Carapace Length ◽  
Critical Size ◽  
Dry Weight ◽  
Shell Morphology ◽  
Strongly Correlated ◽  
Rock Lobster ◽  
Perna Canaliculus ◽  
Jasus Edwardsii ◽  
Innate Behaviour

This paper describes a technique used by juvenile red rock lobsters, Jasus edwardsii, 20–70 mm carapace length, to open and feed on live mussels. This technique appears to be an innate behaviour. The maximum or critical size (shell length) of cultured and wild Mytilus galloprovincialis, and cultured Perna canaliculus, which J. edwardsiiis capable of opening, is strongly correlated with lobster carapace length. Jasus edwardsii is capable of opening significantly larger cultured than wild M. galloprovincialis; this is a reflection of the differences in shell morphology between wild and cultured mussels, and the vulnerability of different shapes to the opening technique employed. In replacement experiments, the greatest numbers of mussels were eaten from the smallest mussel sizes (6–20 mm shell length), whereas the greatest amount of dry flesh weight was consumed from the middle mussel sizes (11–40 mm shell length) for all three mussel types. Dry-weight consumption was considered the most appropriate indicator of preference, the amount of mussel flesh consumed being more relevant to a rock lobster farmer than the numbers of mussels eaten. The preferred mussel size was approximately half the critical size. The application of these results to rock lobster farming is discussed.

The Males of Dialictus laevissimus (Smith) and D. rohweri (Ellis) (Hymenoptera: Halictidae)

1962 ◽  
Vol 94 (11) ◽  
pp. 1228-1231 ◽  
Author(s):  
G. Knerer ◽  
C. E. Atwood
Keyword(s):  
Late Summer ◽  
Early Summer ◽  
Morphological Features ◽  
Limited Area ◽  
Male And Female ◽  
The North ◽  
Junior Author ◽  
The Status ◽  
Males And Females ◽  
Correct Association

Proper association of males with females of the bee family Halictidae presents difficulties not found in most insect groups. In the north temperate zone males emerge in late summer, mate with the females and then die, only females surviving over winter. Collecting in spring and early summer therefore yields only females and only in the later collections do males appear.Correct association between males and females may be secured by excavating burrows after males have emerged from the pupae, by collecting mating pairs or by making such extensive collections in a limited area that statistical evidence may be secured to support conclusions based on morphological features. This technique was used by the junior author in his original studies of Andrenidae and Halictidae (Atwood, 1933) but is by no means a universal practice. Consequently, many species names in the Halictidae are based on descriptions of one sex only while in other instances the association between male and female rests upon a very shaky foundation. This paper is designed to clarify the status of two species which are now in the above categories.

Environmental influences on daily commercial catch rates of South Australia's southern rock lobster (Jasus edwardsii)

2014 ◽  
Vol 23 (4) ◽  
pp. 362-374 ◽  
Author(s):  
John Feenstra ◽  
Richard McGarvey ◽  
Adrian Linnane ◽  
André E. Punt ◽  
Nigel Bean
Keyword(s):  
Environmental Influences ◽  
Rock Lobster ◽  
Commercial Catch ◽  
Jasus Edwardsii ◽  
Catch Rates

Influences of weather and time of day on trap catches of bush fly,Musca vetustissima Walker (Diptera: Muscidae)

1986 ◽  
Vol 76 (3) ◽  
pp. 359-366 ◽  
Author(s):  
W. G. Vogt
Keyword(s):  
Wind Speed ◽  
Relative Humidity ◽  
Solar Radiation ◽  
New South ◽  
Time Of Day ◽  
Weather Variables ◽  
South Wales ◽  
Males And Females ◽  
Catch Rates ◽  
Trap Catches

AbstractField populations of Musca vetustissima Walker were sampled in a region of New South Wales at 2-h intervals on 35 occasions between spring 1984 and autumn 1985 using wind-oriented fly traps. Ambient temperature, solar radiation, relative humidity and wind speed explained 84·3% of the within-day deviance of total catches (both sexes combined). Temperature and solar radiation jointly explained 82·6% of this deviance (71·1 and 11·5%, respectively), indicating that the other variables, although significant, did not greatly affect trap catches. As air temperature increased, log catch rates increased non-linearly up to a maximum at 27·5°C and declined thereafter. Log catch rates increased linearly as solar radiation increased and declined linearly as relative humidity and wind speed increased. Changes in log catch rates with time of day were explained almost entirely by the four weather variables, i.e. when weather effects were removed, time of day effects were no longer significant. These weather variables also accounted for 79·9% of the between-day variation in logarithms of trap catches. Relative responses of males and females to traps differed significantly with respect to relative humidity, wind speed and time of day. Male catches tended to increase relative to female catches between 1200 h and 1800 h and also declined more slowly with increases in relative humidity and wind speed. Separate models are presented for standardization of male and female catch rates; the estimates differ from those obtained from observed sex ratios and total catch rates, but the differences are small compared to the observed day-to-day variation in catch rates.

Relationship between settlement of southern rock lobster pueruli, Jasus edwardsii, and recruitment to the fishery in Tasmania, Australia

2001 ◽  
Vol 52 (8) ◽  
pp. 1271 ◽  
Author(s):  
C. Gardner ◽  
S. D. Frusher ◽  
R. B. Kennedy ◽  
A. Cawthorn
Keyword(s):  
Interannual Variation ◽  
Stock Assessment ◽  
Catch Rate ◽  
Assessment Model ◽  
Rock Lobster ◽  
Commercial Catch ◽  
Jasus Edwardsii ◽  
Catch Rates ◽  
Additional Support ◽  
Northeast Coast

Puerulus catches on artificial collectors were measured monthly at four sites around Tasmania from 1991 to April 2000, with the aim of predicting future changes in recruitment to the fishery. Support for the potential of catch-rate prediction in Tasmania was provided at the two sites that have overlap of several years between indices of puerulus settlement and indices of the abundance of recruits to the fishery. At Bicheno, on the northeast coast, correlations between annual puerulus index and commercial catch rates were highly significant, with a lag of 5 years (P< 0.01). Similar interannual trends in puerulus index and estimates from a stock-assessment model of the biomass of recruits to the fishery provided additional support for a link with puerulus index. A 5-fold interannual variation in puerulus index detected at Bicheno, with a peak in 1995, was preceded by 3 years of relatively low puerulus catch. The peak in puerulus index appears to lead to an increase in the abundance of sublegal males in research sampling 3 years later. Correlation between annual measures of puerulus index and catch rate also appeared significant at King Island (P= 0.06) although data at this site had less contrast.

Calibration of trap catches and net catches for estimating population densities of the bush fly Musca vetustissima (Diptera: Muscidae)

1992 ◽  
Vol 82 (4) ◽  
pp. 539-546 ◽  
Author(s):  
W.G. Vogt
Keyword(s):  
Sampling Methods ◽  
Population Densities ◽  
Male And Female ◽  
Coefficients Of Variation ◽  
Males And Females ◽  
Trap Catches

AbstractPopulation densities of male and female Musca vetustissima Walker were estimated from recapture rates of marked flies in baited fly traps. Marked flies of laboratory and field origin were equally trappable. Trap catches of field flies were also compared with net catches for which the human collector was the source of attraction, and relationships are presented for estimating population densities based on both sampling methods. Estimates of fly density from trap and net catches at fixed locations have similar precision, coefficients of variation being approximately 55% for both males and females of M. vetustissima. Comparison of estimated fly densities (flies/ha) and annoyance indices, estimated numbers of flies approaching a collector each minute at 29.5°C, in ‘good’ and ‘bad’ fly years suggests that M. vetustissima is a potential nuisance whenever population densities exceed 1000 flies/ha.

Size-structured population modelling and risk assessment of the Victorian southern rock lobster, Jasus edwardsii, fishery

2001 ◽  
Vol 52 (8) ◽  
pp. 1495 ◽  
Author(s):  
David Hobday ◽  
André E. Punt
Keyword(s):  
Egg Production ◽  
Stock Assessment ◽  
Reference Points ◽  
Assessment Model ◽  
Data Series ◽  
Population Modelling ◽  
Rock Lobster ◽  
Southeastern Australia ◽  
Jasus Edwardsii ◽  
Catch Rates

Current annual landings of southern rock lobster, Jasus edwardsii, from southeastern Australia are around 5000 tonnes valued at A$140 million. The Victorian component of this catch during the 1998-99 fishing season was 550 t, valued at A$18 million. During the past 20 years catch rates have declined from 0.8 kg per pot lift to 0.6 and 0.3 kg per pot lift in the western and eastern management zones respectively. The fishery has been managed with input controls during this period, but at the time of writing, the direction of future management is not clear. A size-structured model was developed to assess risk associated with both effort (input) and catch (output) controlled harvest strategies in each zone. The stock-assessment model was fitted to historical catch data (in weight and by number) from 1951, catch rates, and the length-frequency by sex. The uncertainty associated with the estimates of exploitable biomass and egg production was assessed according to Bayesian methods. The output of the assessment formed the basis for projections intended to determine the risk associated with different future levels of effort and catch. Reference points based on estimated biomass and egg production relative to the start of the data series in 1951 were considered.

scholarly journals Estimating survival of rock lobsters from long-term tagging programmes: how survey number and interval influence estimates

2015 ◽  
Vol 72 (suppl_1) ◽  
pp. i244-i251 ◽  
Author(s):  
Ziya Kordjazi ◽  
Stewart Frusher ◽  
Colin D. Buxton ◽  
Caleb Gardner
Keyword(s):  
Survival Probability ◽  
Marine Science ◽  
Rock Lobster ◽  
Time Intervals ◽  
Male And Female ◽  
Project Duration ◽  
Equal Time ◽  
Sustainable Exploitation ◽  
Jasus Edwardsii

Abstract A long-term tagging dataset on southern rock lobster (Jasus edwardsii) conducted at the Crayfish Point Scientific Reserve near Hobart, Tasmania, Australia, was used to determine how survey number and survey duration affected the precision of survival estimates of male and female lobsters to ensure sustainable exploitation of the population. Tagging surveys were undertaken twice yearly during 2000–2003 with unequal time-intervals between surveys and then once a year with equal time-intervals during 2004–2012 during the January–February period. The most parsimonious Cormack–Jolly–Seber model for estimating survival of lobsters was dependent on (i) timing of the tagging and recapture surveys, (ii) time between consecutive recapture surveys, and (iii) gender. The number of surveys required to provide a precise survival probability varied with gender and time between recapture surveys. For surveys where there was unequal time between recapture surveys, seven and five surveys were required for female and male lobsters, respectively, whereas only five surveys were required when annual surveys were undertaken. Thus, lobster tagging projects using annual surveys should ideally extend to at least 5 years, which is beyond the 3-year project duration common in marine science.

scholarly journals THE EFFECT OF COOKING ON CARAPACE LENGTH OF SOUTHERN ROCK LOBSTER, JASUS EDWARDSII (HUTTON, 1875) (DECAPODA, PALINURIDAE)

Crustaceana ◽  
2001 ◽  
Vol 74 (2) ◽  
pp. 221-224
Author(s):  
Sam Ibbott ◽  
Stewart Frusher ◽  
Caleb Gardner
Keyword(s):  
Carapace Length ◽  
Rock Lobster ◽  
Jasus Edwardsii
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