scholarly journals Condition of larvae of western rock lobster (Panulirus cygnus) in cyclonic and anticyclonic eddies of the Leeuwin Current off Western Australia

2015 ◽  
Vol 66 (12) ◽  
pp. 1158 ◽  
Author(s):  
Miao Wang ◽  
Richard O'Rorke ◽  
Anya M. Waite ◽  
Lynnath E. Beckley ◽  
Peter Thompson ◽  
...  
Keyword(s):  
Western Australia ◽  
Spiny Lobster ◽  
Dry Mass ◽  
Leeuwin Current ◽  
Dramatic Decline ◽  
Biochemical Analyses ◽  
Panulirus Cygnus ◽  
Anticyclonic Eddies ◽  
Western Australian ◽  
Stage Viii

Changes in the offshore oceanographic processes are suspected to be the cause of a recent dramatic decline in the settlement of post-larvae of the Western Australian spiny lobster (Panulirus cygnus), which has greatly reduced the productivity from the world’s second-largest spiny lobster fishery. The present study assessed whether there are differences in the nutritional condition of the larvae of P. cygnus sampled from two pairs of cyclonic eddies (CEs) and anticyclonic eddies (AEs). Morphometric and biochemical analyses were undertaken on the mid–late-stage larvae (VI, VII, VIII) sampled offshore from two pairs of adjacent counter-rotating mesoscale eddies in the Leeuwin Current off Western Australia. The results showed that larvae captured from CEs had greater average total dry mass (P<0.001) than those from AEs. Stage VIII larvae from CEs contained more protein (P<0.008) (38.5% ±5.4s.e.) and lipid (P<0.005) (67.2% ±12.1) than did those from AEs. The possible causes for these differences are uncertain but may be related to differences in water temperatures in CEs v. AEs influencing the ability of phyllosomas to accumulate nutritional reserves.

Behaviour of the Western Australian spiny lobster, Panulirus cygnus George, in the field and laboratory

1981 ◽  
Vol 32 (3) ◽  
pp. 399 ◽  
Author(s):  
JS Cobb
Keyword(s):  
Western Australia ◽  
Spiny Lobster ◽  
Local Topography ◽  
Tail Flip ◽  
Panulirus Cygnus ◽  
Western Australian

The behaviour of the spiny lobster, Panulirus cygnus, of Western Australia was studied in the laboratory and field. A brief description of behavioural units is provided. A den residency survey showed only 3% of the lobsters sheltered singly, and the number of lobsters in a single den ranged from 1 to more than 100. Lobsters left dens in the evening and returned in the morning, following specific pathways along the reef face, implying knowledge of the local topography. The lobsters returned to the same area of the reef but not necessarily the same den after foraging. The occupancy of any particular den remained fairly constant over a period of time but changed markedly after a storm. The reactions of lobsters to a predator (Octopus tetricus) released at the mouth of a den were high alert postures, antennae pointing and waving, and slow retreat from the den. In a large laboratory pool, stridulation and tail flip were frequent when an octopus was out of its lair and moving around.

scholarly journals Fatty acid profiles of phyllosoma larvae of western rock lobster (Panulirus cygnus) in cyclonic and anticyclonic eddies of the Leeuwin Current off Western Australia

2014 ◽  
Vol 122 ◽  
pp. 153-162 ◽  
Author(s):  
M. Wang ◽  
R. O’Rorke ◽  
A.M. Waite ◽  
L.E. Beckley ◽  
P. Thompson ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Western Australia ◽  
Fatty Acid Profiles ◽  
Rock Lobster ◽  
Leeuwin Current ◽  
Phyllosoma Larvae ◽  
Panulirus Cygnus ◽  
Anticyclonic Eddies

Changes in lipid and fatty acid composition of late larval and puerulus stages of the spiny lobster (Panulirus cygnus) across the continental shelf of Western Australia

2006 ◽  
Vol 143 (2) ◽  
pp. 219-228 ◽  
Author(s):  
Bruce F. Phillips ◽  
Andrew G. Jeffs ◽  
Roy Melville-Smith ◽  
Chris F. Chubb ◽  
Matthew M. Nelson ◽  
...  
Keyword(s):  
Fatty Acid Composition ◽  
Fatty Acid ◽  
Continental Shelf ◽  
Acid Composition ◽  
Western Australia ◽  
Spiny Lobster ◽  
Panulirus Cygnus

The Leeuwin Current, eddies and sub-Antarctic waters off south-western Australia

2004 ◽  
Vol 55 (3) ◽  
pp. 267 ◽  
Author(s):  
G. R. Cresswell ◽  
D. A. Griffin
Keyword(s):  
Continental Slope ◽  
Western Australia ◽  
Anticyclonic Eddy ◽  
Satellite Observations ◽  
Leeuwin Current ◽  
Deep Mixing ◽  
Complex Interactions ◽  
Antarctic Waters ◽  
Anticyclonic Eddies ◽  
Great Australian Bight

Data from a research vessel cruise in late 1994 and several years of satellite observations revealed complex interactions of ocean features off south-western Australia. The ship measurements showed that the Leeuwin Current (LC) commonly ran at 0.5 m s–1 above the upper continental slope and extended down to approximately 250 m. South of the continent, a 200-km diameter anticyclonic eddy depressed the ocean structure in the upper 1000 m. The eddy showed influences of the LC, deep mixing in winter and summer heating. The sub-Antarctic water around the eddy was cooler, fresher and richer in nutrients and oxygen than both the eddy and the LC. Satellite thermal and topographic measurements showed that cyclonic eddies accelerated the LC along the southern upper continental slope, whereas anticyclonic eddies diverted it out to sea and then back again. The images suggested that weak eddies originating east of the Great Australian Bight migrate westward, first encountering the continental slope off the Recherche Archipelago. There, the anticyclonic eddies take on warm water from the LC and strengthen. Several anticyclonic eddies were followed westward beyond the archipelago for 18 months as they drifted at up to 5 km day–1 and interacted with the LC and with one another.

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.

Increased density, biomass and egg production in an unfished population of Western Rock Lobster (Panulirus cygnus) at Rottnest Island, Western Australia

2007 ◽  
Vol 58 (3) ◽  
pp. 286 ◽  
Author(s):  
R. C. Babcock ◽  
J. C. Phillips ◽  
M. Lourey ◽  
G. Clapin
Keyword(s):  
Western Australia ◽  
Carrying Capacity ◽  
Egg Production ◽  
Carapace Length ◽  
Spiny Lobster ◽  
Shallow Waters ◽  
Recreational Fishing ◽  
Total Biomass ◽  
Rock Lobster ◽  
Panulirus Cygnus

Surveys of spiny lobster (Panulirus cygnus) populations in shallow waters surrounding Rottnest Island in Western Australia revealed much higher levels of density, biomass and egg production in no-take than in fished areas. Density of lobsters was ~34 times higher in the sanctuary, and density of lobsters above minimum legal size around 50 times higher than in other areas around the island where recreational fishing is allowed. Mean carapace length (CL), total biomass and egg production of lobsters in the sanctuary zone were significantly higher than in adjacent fished areas. Large individuals (≥100 mm CL), especially large males, were found almost exclusively within the sanctuary. The abundance of mature animals in these shallow waters indicates that not all P. cygnus migrate to deep water and that shallow water habitats may currently be well below carrying capacity in terms of biomass and egg production. If implemented in a systematic way, unfished areas such as the Kingston Reefs could also provide a useful fisheries-independent tool for assessing trophic interactions and the structure and density of unfished populations, and for estimating parameters such as growth of larger individuals that may be rare or absent in more widely fished populations.

Effect of the Leeuwin Current on the Recruitment of Fish and Invertebrates along the Western Australian Coast

1996 ◽  
Vol 47 (2) ◽  
pp. 147 ◽  
Author(s):  
N Caputi ◽  
WJ Fletcher ◽  
A Pearce ◽  
CF Chubb
Keyword(s):  
Western Australia ◽  
Positive Impact ◽  
Larval Survival ◽  
Negative Influence ◽  
Positive Influence ◽  
Major Influence ◽  
Larval Phase ◽  
Leeuwin Current ◽  
Shark Bay ◽  
Western Australian

The relatively high catch of invertebrate species compared with finfish off Western Australia is in sharp contrast to other regions of the world, where finfish production usually dominates. This low level of finfish production is primarily due to the Leeuwin Current, which consists of warm, low-nutrient waters flowing south along the edge of the continental shelf of the Western Australian coast. In contrast, the other eastern boundary currents in the Southern Hemisphere (Humboldt and Benguela) are associated with upwelling of cool, nutrient-rich waters flowing north and the high rates of primary production resulting in a large finfish production. The Leeuwin Current, being the dominant oceanographic feature off Western Australia, has a major influence on the abundance of many species. The larval phase is the stage mainly affected by the current, but not always with the same result. For example, the strength of the Leeuwin Current has a significant positive influence during the larval stage of the western rock lobster (Panulirus cygnus). However, the current has a negative influence during the larval life of the scallop, Amusium balloti, in Shark Bay. Similarly for the pelagic finfish species, the current has a negative effect on larval survival of pilchards (Sardinops sagax neopilchardus) but a positive impact for whitebait (Hyperlophus vittatus). Possible mechanisms for the effect of the current include transportation of larvae and temperature effects on spawning success and on survival and growth of larvae.

scholarly journals Phyllosomata associated with large gelatinous zooplankton: hitching rides and stealing bites

2014 ◽  
Vol 72 (suppl_1) ◽  
pp. i124-i127 ◽  
Author(s):  
Richard O'Rorke ◽  
Shane D. Lavery ◽  
Miao Wang ◽  
Ramón Gallego ◽  
Anya M. Waite ◽  
...  
Keyword(s):  
High Throughput ◽  
Western Australia ◽  
Late Stage ◽  
High Throughput Sequencing ◽  
Spiny Lobster ◽  
Gelatinous Zooplankton ◽  
Rock Lobster ◽  
Panulirus Cygnus

Abstract During a zooplankton survey 350 km off the coast of Western Australia, we captured a large and robust zooid of a salp (Thetys vagina), to which six late stage larvae (phyllosomata) of the western rock lobster (Panulirus cygnus) were attached. High-throughput sequencing analyses of DNA extracts from midgut glands of the larvae confirmed that each phyllosoma had consumed mainly salp tissue (x¯ = 64.5% ± 15.9 of DNA reads). These results resolve long-standing conjecture whether spiny lobster phyllosomata attach to large gelatinous hosts to feed on them.

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.

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