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.

scholarly journals Queuing, takeovers, and becoming a fat cat: Long-term data reveal two distinct male spatial tactics at different life-history stages in Namibian cheetahs

Ecosphere ◽  
2018 ◽  
Vol 9 (6) ◽  
pp. e02308 ◽  
Author(s):  
Joerg Melzheimer ◽  
Sabrina Streif ◽  
Bernd Wasiolka ◽  
Manuela Fischer ◽  
Susanne Thalwitzer ◽  
...  
Keyword(s):  
Life History ◽  
Life History Stages ◽  
Term Data

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.

scholarly journals Identifying indicators of the effects of fishing using alternative models, uncertainty, and aggregation error

2011 ◽  
Vol 68 (7) ◽  
pp. 1417-1425 ◽  
Author(s):  
Sarah J. Metcalf ◽  
Matthew B. Pember ◽  
Lynda M. Bellchambers
Keyword(s):  
Economic Value ◽  
Ecosystem Change ◽  
Small Fish ◽  
Rock Lobster ◽  
Commercial Catch ◽  
Alternative Models ◽  
Qualitative Models ◽  
Lobster Fishery ◽  
Panulirus Cygnus

Abstract Metcalf, S. J., Pember, M. B., and Bellchambers, L. M. 2011. Identifying indicators of the effects of fishing using alternative models, uncertainty, and aggregation error. – ICES Journal of Marine Science, 68: 1417–1425. The identification of indicators of the indirect effects of fishing is often an issue for fisheries management, particularly if just commercial catch data are available. Complex, intermediate, and simplified qualitative models were produced for a fishery case study off Western Australia to identify potential indicators of ecosystem change attributable to western rock lobster (Panulirus cygnus) extraction and bait input. Models of intermediate complexity were used to identify indicators because they produced the least aggregation error. Structural uncertainty was considered through a series of structurally different intermediate models. These alternate models consistently predicted that extraction of rock lobster may positively impact small fish of low economic value, such as old wife (Enoplosus armatus), footballer sweep (Neatypus obliquus), and king wrasse (Coris auricularis). These small fish were therefore identified as potential indicators of the effects of rock lobster extraction. Small crustaceans (amphipods and isopods) also displayed positive impacts attributable to bait input from the rock lobster fishery and were identified as potential indicators of bait effects. Monitoring of these indicators may aid the detection of ecosystem change caused by the rock lobster fishery.

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.

Predicting the recreational western rock lobster (Panulirus cygnus) catch in Western Australia

2001 ◽  
Vol 52 (8) ◽  
pp. 1527 ◽  
Author(s):  
Roy Melville-Smith ◽  
Sonia M. Anderton ◽  
Nick Caputi
Keyword(s):  
Western Australia ◽  
Coastal Management ◽  
Southern Region ◽  
Recreational Fishing ◽  
Rock Lobster ◽  
Commercial Catch ◽  
Mail Surveys ◽  
Panulirus Cygnus ◽  
Multipleregression Analysis ◽  
Better Than

The number of fishers purchasing recreational rock-lobster licences in Western Australia increased from ~15 000 during 1986–87 to 33 000 during 1998–99. The quantity landed was estimated from mail surveys conducted during this period. The recreational catch of western rock lobster increased from approximately 220 to 630 tonnes, or from 1.8% to 4.8% of the commercial catch. This study has shown that total recreational catches of western rock lobster in Western Australia are correlated with licence usage rates (r2 = 0.81) and puerulus settlement indices at Alkimos, in the southern region of the fishery, 3 to 4 years earlier (r2 = 0.59). A multipleregression analysis using both of these variables (r2 = 0.91) was used to predict future recreational lobster catches. If future usage were to remain at 1998–99 levels, it is predicted that the recreational catch would be 700 t in 1999–2000, 650 t in 2000–01, and 550 t in 2001–02. We attempted to improve predictions by analysing the data according to puerulus settlement and licence usage in the two coastal management regions. The correlation for the southern region (where most of the recreational fishing is concentrated) was marginally better than that for the total fishery (r2 = 0.93), but the correlation was poor for the northern coastal zone (r2 = 0.55), where licence usage has been relatively steady and where the recreational catch has consistently remained at around 98 t per annum over the last decade.

Abundance and size of western rock lobster (Panulirus cygnus) as a function of benthic habitat: implications for ecosystem-based fisheries management

2010 ◽  
Vol 61 (3) ◽  
pp. 279 ◽  
Author(s):  
Lynda M. Bellchambers ◽  
Scott N. Evans ◽  
Jessica J. Meeuwig
Keyword(s):  
Fisheries Management ◽  
Single Species ◽  
Benthic Habitat ◽  
Ecological Interactions ◽  
Rock Lobster ◽  
Important Species ◽  
Effective Implementation ◽  
Panulirus Cygnus ◽  
Ecosystem Based Fisheries Management ◽  
The Relationship

Ecosystem-based fisheries management (EBFM) requires the expansion of fisheries research programs to include the relationship between target species and their habitats such that trophic and other ecological interactions can be assessed. The western rock lobster (Panulirus cygnus) is an ecologically important species that supports Australia’s most valuable single-species fisheries. We tested the relationship between abundance and size of western rock lobster and benthic habitats based on the annual independent breeding stock survey and benthic towed video transects. The work was undertaken at Dongara, Jurien Bay and Lancelin, Western Australia between 2005 and 2007. Abundance of western rock lobster was significantly but moderately related to benthic habitat (adjR2 = 0.28), with high abundances associated with high cover of mixed assemblage and Ecklonia sp. Size was effectively predicted by habitat (adjR2 = 0.65) with larger lobsters found in mixed assemblages with sponge and smaller lobsters associated with mixed assemblage with Ecklonia sp. Our study has shown that understanding the influence of habitat and fishing pressure on the abundance and size of targeted species is a critical step in the effective implementation of EBFM.

Relative influence of environmental factors and processing techniques on Panulirus cygnus morbidity and mortality during simulated live shipments

1997 ◽  
Vol 48 (8) ◽  
pp. 839 ◽  
Author(s):  
Patrick T. Spanoghe ◽  
P. K. Bourne
Keyword(s):  
Mortality Rate ◽  
Mortality Rates ◽  
Morbidity And Mortality ◽  
Rock Lobster ◽  
Significant Difference ◽  
Panulirus Cygnus ◽  
Chilling Period ◽  
Processing Techniques ◽  
Western Australian ◽  
Positive Significant Correlation

In this study, conducted in collaboration with the Western Australian rock lobster industry during the 1992–93 fishing season, daily records were made on morbidity and mortality of western rock lobsters, Panulirus cygnus, held in commercial shipping (export) cartons. The aims were to measure the rates of morbidity + mortality and to identify patterns of correlation of morbidity + mortality rates for a range of environmental variables recorded by the processors. In three processing units, the rate of morbidity + mortality in simulated live shipments averaged 5á2% (±0·6), with a highly significant difference (P<0·001) between processing units. Three factors, holding time in export cartons, ambient temperature within the export cartons and chilling period before packing lobsters, had the greatest influence on the rate of morbidity + mortality. Morbidity + mortality rate of animals held for 30–36 h (10·4 ± 2·3%) was twice that of animals held for 20–24 h (5·2 ± 0·6%). A positive significant correlation (r = 0·25, P = 0·001) was identified between morbidity + mortality rate and the internal carton temperature. Aprolongation of the chilling period was reflected by improved survival, possibly resulting from an anaesthesic effect of the chilling treatment.

Spatial Model for the Population Dynamics and Exploitation of the Western Australian Rock Lobster, Panulirus cygnus

1993 ◽  
Vol 50 (8) ◽  
pp. 1650-1662 ◽  
Author(s):  
Carl J. Walters ◽  
Norm Hall ◽  
Rhys Brown ◽  
Chris Chubb
Keyword(s):  
Carapace Length ◽  
Temporal Dynamics ◽  
Population Analysis ◽  
Fishing Effort ◽  
Management Policy ◽  
Rock Lobster ◽  
Breeding Grounds ◽  
Panulirus Cygnus ◽  
Biological Assessments ◽  
Western Australian

There is concern about whether long-standing regulatory measures (size and effort limits) are adequate to protect spawning stocks of the Western Australian rock lobster, Panulirus cygnus, and assure the highest average yields. Virtual population analysis and tagging studies indicate that exploitation rates are extremely high (possibly exceeding 70%/yr) on younger, mainly immature lobsters. To predict the efficacy of alternative regulatory schemes, it has been necessary to explicitly model the spatial and temporal dynamics of lobster abundance and fishing effort. Puerulus settlement (at age 9–11 mo) is mainly into shallow-water (< 40 m) areas, and at 3–5 yr of age in most areas, there is a migration into deeper water where the animals mature after a further 1–2 yr. The size at migration (70–90 mm carapace length) ensures that at least some animals will have a chance to reach the breeding grounds offshore, where fishing effort has historically been lower than inshore, before they reach the minimum legal size (76 mm carapace length). By explicitly modelling the effort distribution as well as lobster movement and stock distribution, we hope to anticipate some consequences of changes in management policy that could not be predicted from biological assessments alone.

scholarly journals Possible ecosystem impacts of applying MSY policies from single-species assessment

2005 ◽  
Vol 62 (3) ◽  
pp. 558-568 ◽  
Author(s):  
Carl J. Walters ◽  
Villy Christensen ◽  
Steven J. Martell ◽  
James F. Kitchell
Keyword(s):  
Time Series Data ◽  
Single Species ◽  
Maximum Sustainable Yield ◽  
Series Data ◽  
Ecosystem Structure ◽  
Widespread Application ◽  
Predator Species ◽  
Ecosystem Impacts ◽  
Term Data

Abstract Ecosim models have been fitted to time-series data for a wide variety of ecosystems for which there are long-term data that confirm the models' ability to reproduce past responses of many species to harvesting. We subject these model ecosystems to a variety of harvest policies, including options based on harvesting each species at its maximum sustainable yield (MSY) fishing rate. We show that widespread application of single-species MSY policies would in general cause severe deterioration in ecosystem structure, in particular the loss of top predator species. This supports the long-established practice in fisheries management of protecting at least some smaller “forage” species specifically for their value in supporting larger piscivores.

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.

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