Testing collector designs for commercial harvesting of western rock lobster (Panulirus cygnus) puerulus

2001 ◽  
Vol 52 (8) ◽  
pp. 1465 ◽  
Author(s):  
Bruce F. Phillips ◽  
Roy Melville-Smith ◽  
Yuk Wing Cheng ◽  
Mark Rossbach
Keyword(s):  
Published Data ◽  
Rock Lobster ◽  
Different Depths ◽  
New Moon ◽  
Catch Rates ◽  
Highly Correlated ◽  
Carry Over ◽  
Panulirus Cygnus ◽  
Do So ◽  
Commercial Harvesting

We have (i) tested modified western rock lobster sandwich collectors at different depths and distances offshore (ii) tested different collector designs (iii) examined the effect of collector size, and (iv) tested the effect of frequency of servicing the collectors. The only catches recorded in the onshore-offshore trials were on gear set at the inshore site (depths <5 m). Published data from the 1970s on the effect on catches of collector arrays and locations were reexamined with a general linear model. The analysis revealed marginally significant corner and layer effects, carry-over effects, and square-of-time effects. Five collector designs were therefore set in the shallows, two of which had replicates of three different sizes, and were checked over four lunar months during peak settlement. Sandwich collectors had significantly better catch rates than others (P <0.001), and settlement rates were highly correlated with collector dimensions (r = 0.72). Daily servicing for seven days around the time of new moon yielded catches 170% higher than those from a single monthly servicing (P <0.001). Results indicate that tests for collectors must take into account corner, carry-over, neighbour, and layer effects and that to do so they must be set out in an array and repositioned after each sampling.

scholarly journals The orientation and migratory dynamics of the western rock lobster, Panulirus cygnus, in Western Australia

2014 ◽  
Vol 71 (5) ◽  
pp. 1052-1063 ◽  
Author(s):  
Simon de Lestang
Keyword(s):  
Large Scale ◽  
Economic Benefits ◽  
Rock Lobster ◽  
Commercial Catch ◽  
Breeding Grounds ◽  
Mean Size ◽  
Catch Rates ◽  
Panulirus Cygnus ◽  
The Impact ◽  
Oceanic Currents

Abstract Large-scale migrations are known to occur in numerous species, and in the case of the Western Rock Lobster, Panulirus cygnus, result in juveniles moving from nursery areas into deeper offshore breeding grounds. In 2008 the Western Rock Lobster fishery reduced harvest rates to increase legal and spawning biomass throughout the fishery, which also allowed greater numbers of lobsters to migrate. Increased lobster migration could potentially reduce biomass in some areas, thus adversely impacting commercial catch rates. Over 20 000 tag–recaptured lobsters were analysed to determine the dynamics underlying migration in this species and to assess the impact reduced harvest rates may have had on catches. This study showed that P. cygnus migration was associated with body size and water depth, and that magnetism and oceanic currents appear to be the most likely guideposts used for orientation. Size at migration varied in a constant fashion along the coast, being larger towards the southern end of the fishery and smallest at the offshore Abrolhos Islands. During the migration period, up to 50% of lobsters at their mean size of migration moved from coastal areas out towards deeper waters (>40 m), whereas <15% of those in deeper water at the same size moved significant distances northward. This behaviour appears to be contranatant, counteracting the downstream redistribution of larvae after their 9–11 month larval life. Reduced harvest rates and catches being focussed onto higher valued sedentary lobsters have allowed more lobsters to migrate. However, the numbers moving between management areas are relatively small, with the biological and economic benefits of fishing at a reduced exploitation rate outweighing losses to catches.

Aspects of the population dynamics of the western rock lobster, Panulirus cygnus George. II. Seasonal changes in the catchability coefficient

1974 ◽  
Vol 25 (2) ◽  
pp. 249 ◽  
Author(s):  
GR Morgan
Keyword(s):  
Population Dynamics ◽  
Population Density ◽  
Water Temperature ◽  
Linear Combination ◽  
Seasonal Changes ◽  
Stock Assessment ◽  
Water Salinity ◽  
Rock Lobster ◽  
Highly Correlated ◽  
Panulirus Cygnus

The catchability coefficient, q, of a population of the western rock lobster P. cygnus was calculated monthly from November 1969 to January 1973 using measurements of catch, effort, population density, and area of reef. The catchability coefficient varied significantly during this time and was positively correlated with water temperature and water salinity, and negatively correlated with the percentage of rock lobsters in a premoult condition. A linear combination of these three factors was highly correlated with the catchability coefficient (P < 0.001) and appears to offer a method of adjusting the catchability coefficient and so leading to an improved stock assessment for this species.

Environmental effects on recruitment of the western rock lobster, Panulirus cygnus

2001 ◽  
Vol 52 (8) ◽  
pp. 1167 ◽  
Author(s):  
Nick Caputi ◽  
Chris Chubb ◽  
Alan Pearce
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Larval Survival ◽  
Current Strength ◽  
Sea Surface ◽  
Rock Lobster ◽  
Leeuwin Current ◽  
Westerly Winds ◽  
Highly Correlated ◽  
Panulirus Cygnus

The Leeuwin Current, which brings warm, nutrient-poor waters southward along the edge of the West Australian continental shelf, is positively correlated with western rock lobster (Panulirus cygnus) puerulus settlement along the coast. Westerly winds, also positively correlated with puerulus settlement, probably assist the transport of larvae to the coast during settlement. We examined relationships between (a) monthly sea-surface temperature where phyllosoma larvae occur – and annual levels of puerulus settlement at locations throughout the fishery and (b) monthly variation in Leeuwin Current strength (and westerly winds) and annual puerulus settlement later in the year (August–January). The Leeuwin Current, when it begins to strengthen during February–April, was highly correlated with puerulus settlement; sea-surface temperature during this period may have strongly influenced puerulus settlement at many locations. Its influence on puerulus settlement may have been due to improved larval survival and growth caused by higher water temperatures associated with a stronger Leeuwin Current in April or to increased retention of larvae close to the coast. In years when the southward-flowing Leeuwin Current was very strong, settlement in the southern locations was relatively higher than that farther north. In years of strong puerulus settlement, settlement also occurred earlier in the season.

scholarly journals Towards Reduced CNNs for De-Noising Phase Images Corrupted with Speckle Noise

Photonics ◽  
2021 ◽  
Vol 8 (7) ◽  
pp. 255
Author(s):  
Marie Tahon ◽  
Silvio Montresor ◽  
Pascal Picart
Keyword(s):  
Phase Error ◽  
Speckle Noise ◽  
Experimental Conditions ◽  
Benchmark Data ◽  
Wide Range ◽  
Phase Images ◽  
Different Depths ◽  
Phase Data ◽  
Do So

Digital holography is a very efficient technique for 3D imaging and the characterization of changes at the surfaces of objects. However, during the process of holographic interferometry, the reconstructed phase images suffer from speckle noise. In this paper, de-noising is addressed with phase images corrupted with speckle noise. To do so, DnCNN residual networks with different depths were built and trained with various holographic noisy phase data. The possibility of using a network pre-trained on natural images with Gaussian noise is also investigated. All models are evaluated in terms of phase error with HOLODEEP benchmark data and with three unseen images corresponding to different experimental conditions. The best results are obtained using a network with only four convolutional blocks and trained with a wide range of noisy phase patterns.

scholarly journals ANÁLISE INTER-RELACIONAL DE INDICADORES DE ABSENTEÍSMO E TURNOVER: O CASO DE UMA INDÚSTRIA TÊXTIL DO LITORAL NORTE DE SANTA CATARINA

2018 ◽  
Vol 7 (1) ◽  
pp. 95-110
Author(s):  
Ana Célia Bohn ◽  
Sidnei Gripa ◽  
Nelson Hein ◽  
Adriana Kroenke
Keyword(s):  
Organizational Behavior ◽  
Single Case ◽  
Santa Catarina ◽  
Organizational Research ◽  
Exploratory Approach ◽  
Proposal A ◽  
Highly Correlated ◽  
Behavioral Criteria ◽  
Do So

Os pesquisadores têm analisado separadamente, os indicadores de absenteísmo e turnover como critérios comportamentais em investigação organizacional. Nesse sentido, observa-se pouca atenção dada à sua possível inter-relação. Este estudo tem como objetivo analisar a inter-relacão dos indicadores de absenteísmo e turnover a fim de entender se há relações envolvidas nesses indicadores. O estudo foi baseado no construto de Migliolli e Kroenke (2016), e recebeu enquanto delineamento metodológico uma pesquisa do tipo quantitativa, longitudinal, em caráter de testagem empírica, de abordagem exploratória, com objeto de estudo um caso único, pautados na conveniência de pesquisa. Para tanto, partiu-se do pressuposto de que a integração desses indicadores pode fornecer orientações sobre alguns comportamentos organizacionais. Para consubstanciar a proposta foi construída uma função sinusóide. Os resultados apontam com algumas exceções que o turnover está altamente correlacionado com o absenteísmo, ou seja, o start para o turnover é o alto índice de absenteísmo. Conclui-se que para a empresa diminuir o seu índice de turnover é preciso primeiro implantar ações para a diminuição do índice de absenteísmo.Palavras-Chave: Absenteísmo. Turnover. Inter-relação. Abstract: Researchers have been analyzing separately the absenteeism indicators and turnover as behavioral criteria in organizational research. In this regard, it is observed the lack of attention given to its possible interrelation. This study aims to analyze the absenteeism indicators interrelation and turnover to understand if there are any associations involved in these indicators. The study was based on Migliolli and Kroenke’s (2016) construct, and while it was a methodological design, received a research of quantitative and longitudinal nature, with empirical and testing aspects, exploratory approach, using a single case as the studying subject, based on the research’s convenience. To do so, it was assumed that the integration of these indicators can provide guidance on some organizational behavior. To substantiate the proposal, a sinusoid function was made. The results point with a few exceptions that the turnover is highly correlated with absenteeism, that is, the start for turnover is the high absenteeism index. So, it is concluded that for the company to decrease its turnover index it is necessary to first implement actions to reduce the absenteeism index.Keywords: Absenteeism. Turnover. Interrelation.

scholarly journals Lunar periodicity in catch rate and reproductive condition of adult eastern king prawns, Penaeus plebejus, in coastal waters of south-eastern Queensland, Australia

1996 ◽  
Vol 47 (1) ◽  
pp. 67 ◽  
Author(s):  
AJ Courtney ◽  
DJ Die ◽  
JG McGilvray
Keyword(s):  
Coastal Waters ◽  
Full Moon ◽  
Lunar Cycle ◽  
Catch Rate ◽  
Lunar Phase ◽  
Reproductive Condition ◽  
Ovary Weight ◽  
South Eastern ◽  
New Moon ◽  
Catch Rates

This study examined the lunar and die1 variation in catch rates and reproductive condition of adult eastern king prawns, Penaeus plebejus, in relatively deep (160 m) coastal waters off south- eastern Queensland. Females numerically dominated catches over most of the lunar cycle and constituted 76% of the weight of the catch. Analysis of variance (ANOVA) revealed an interaction between lunar phase and sex; catches peaked during Lunar Phase 3 (full moon � 3 days) and were particularly marked for males. This was the only period during the lunar cycle when the sex ratio approached 1 : 1. There was also an interaction between trawl-time and sex; male catch rates were at a minimum early in the evening, whereas female catch rates were at a maximum then and declined throughout the night. Trawler logbook catch rate data from the same area over a similar period indicated an interaction between lunar cycle and lunar phase. ANOVA revealed an effect of the interaction between phase and sex on the incidence of soft prawns; the incidence of soft males increased during Phase 4 (half moon waning to new moon � 3 days). Ovary weight also varied between phases and was higher during Phases 2 (half moon waxing to full moon � 3 days) and 4 (half moon waning to new moon � 3 days). Trends in the ovary weight and the incidence of histologically mature and ripe females suggested there are two periods of increased spawning activity during each lunar cycle. A cyclic regression fitted to the data explained 93% of the variation in the incidence of ripe females between samples. The influence of these cyclic trends in catch rate and reproductive condition should be considered when monitoring the spawning stock in the fishery and when planning sampling strategies in any future reproductive studies.

scholarly journals Spatial and temporal changes in egg production in the western rock lobster(Panulirus cygnus)fishery

2009 ◽  
Vol 43 (1) ◽  
pp. 151-161 ◽  
Author(s):  
Roy Melville‐Smith ◽  
Simon De Lestang ◽  
Adrian W. Thomson
Keyword(s):  
Egg Production ◽  
Temporal Changes ◽  
Rock Lobster ◽  
Spatial And Temporal Changes ◽  
Panulirus Cygnus

scholarly journals Stocking density and shelter type for the optimal growth and survival of western rock lobster Panulirus cygnus (George)

Aquaculture ◽  
2006 ◽  
Vol 260 (1-4) ◽  
pp. 114-127 ◽  
Author(s):  
Danielle Johnston ◽  
Roy Melville-Smith ◽  
Blair Hendriks ◽  
Greg B. Maguire ◽  
Bruce Phillips
Keyword(s):  
Stocking Density ◽  
Optimal Growth ◽  
Rock Lobster ◽  
Growth And Survival ◽  
Panulirus Cygnus

Spatial and temporal variation in lipid and fatty acid profiles of western rock lobster pueruli at first settlement: biochemical indicators of diet and nutritional status

2009 ◽  
Vol 60 (8) ◽  
pp. 810 ◽  
Author(s):  
A. J. Limbourn ◽  
R. C. Babcock ◽  
D. J. Johnston ◽  
P. D. Nichols ◽  
B. Knott
Keyword(s):  
Fatty Acid ◽  
Nutritional Status ◽  
Spatial And Temporal Variation ◽  
Lipid Levels ◽  
Rock Lobster ◽  
Important Species ◽  
Fa Composition ◽  
Lipid Fatty Acid ◽  
Spatial And Seasonal Variation ◽  
Panulirus Cygnus

Rock lobster species are found worldwide and have a life history that includes development through a planktonic phyllosoma followed by a nektonic non-feeding puerulus that relies on stored energy during recruitment into near-shore habitats. Recruitment to adult populations of western rock lobster (Panulirus cygnus) is highly variable and is likely to be strongly influenced by shelf width and oceanic conditions affecting cross-shelf transport and nutrition. Since the nutritional status of newly settled pueruli will reflect the phyllosoma feeding environment and distance swum, we studied levels of lipid, fatty acid (FA) and protein of 422 pueruli and 79 first instar juveniles from four Western Australian locations. Lipid levels generally were inversely related to shelf width but were variable, suggesting pueruli may travel complex trajectories to coastal settlement. Lipid and FA composition of pueruli were consistent with spatial and seasonal variation in Leeuwin Current and coastal productivity regimes. Seasonal differences in FA composition occurred regardless of the year of settlement. Pueruli had lower lipid levels during ENSO years, when recruitment tends to be lower also. Measures of puerulus nutritional status appear to provide valuable insights into the processes underpinning recruitment in Panulirus cygnus and other commercially and ecologically important species.

Potential of a trap-fishery for deep-water rock lobster Palinurus delagoae off South Africa

1997 ◽  
Vol 48 (8) ◽  
pp. 993 ◽  
Author(s):  
J. C. Groeneveld ◽  
A. C. Cockcroft
Keyword(s):  
South Africa ◽  
South African ◽  
Deep Water ◽  
Linear Models ◽  
Depth Interval ◽  
Suitable Habitat ◽  
Rock Lobster ◽  
Experimental Phase ◽  
Trap Fishery ◽  
Catch Rates

An experiment to investigate the potential of a trap-fishery for deep-water rock lobster Palinurus delagoae was conducted off the east coast of South Africa between 1994 and 1996. The 75–425 m depth interval between 27°S and 32°S was stratified according to depth and latitude, and three regions (North, Central and South) were sampled systematically over the three years. Sampling by commercial vessels operating long-lines and traps included an experimental phase (fixed fishing positions) and a commercial phase (no restriction on fishing location). Generalized linear models were used to investigate the influence of year, region, sampling phase, month and soak time. Sampling phase was significant, with traps set during the commercial phase catching more than those set in the experimental phase. The effect of soak time on catch rates was not significant. The almost-50% decrease in the combined abundance index combined with a marked decrease in mean lobster size over the study period suggests a relatively low fisheries potential for this species in South African waters; this may be attributable to the relative scarcity of suitable habitat in the area.

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