Developing a cost-effective puerulus collector for the southern rock lobster (Jasus edwardsii) aquaculture industry

2004 ◽  
Vol 31 (1-2) ◽  
pp. 1-15 ◽  
Author(s):  
David Mills ◽  
Bradley Crear
2007 ◽  
Vol 58 (3) ◽  
pp. 273 ◽  
Author(s):  
Daniel J. Brock ◽  
Peter J. Hawthorne ◽  
Timothy M. Ward ◽  
Adrian J. Linnane

The effectiveness of two monitoring programs, designed to describe and quantify the bycatch from commercial pots, was examined in the South Australian rock lobster (Jasus edwardsii) fishery (SARLF). The first, logbook sampling, relied on information collected and recorded by fishers in logbooks. The second, bycatch sampling, required fishers to collect bycatch specimens on a nominated day for later scientific analysis. A total of 40 bycatch species were recorded during the study. Finfish, mainly blue-throat wrasse (Notolabrus tetricus) and leather jacket species (Meuschenia hippocrepis and Meushenia australis), were the major component (>90% by number). Data from the logbook program were appropriate for monitoring spatio-temporal trends in bycatch, whereas the bycatch sampling provided more accurate information on bycatch species. Each program was subject to bias when estimating total bycatch numbers and, as a result, a combination of both methods indicated a cost-effective and appropriate way with which to monitor bycatch from the fishery. In comparison with other fisheries, bycatch from the SARLF was relatively low; however, because bycatch was dominated by relatively few species, ongoing monitoring and risk assessment of these populations is needed to ensure long-term sustainability of bycatch levels.


2001 ◽  
Vol 52 (8) ◽  
pp. 1067 ◽  
Author(s):  
John D. Booth ◽  
Dean R. Stotter ◽  
Jeffrey S. Forman ◽  
Elizabeth Bradford

Interannual changes in juvenile abundance can validate interannual changes in levels of settlement on collectors and address such postsettlement processes as density-dependent mortality. A strong pulse of postlarval Jasus edwardsii recruitment took place near Wellington in 1991–92, followed by much lower settlement. To determine whether juvenile abundances by age would reflect this pulse and so validate the collector catches, divers estimated quarterly the abundance and size of juveniles at six sites, from 1993 to 2000. Juveniles younger than 2 years were uncommon. At four sites, 2+ and 3+ lobsters were present in large proportion until March 1995. From June 1995, most were at least 3+. These data were consistent with progress of the 1991–92 modal group through the age-frequency distributions, after which juvenile abundances declined, thereby reflecting the settlement data. The other two sites differed in that 2+ and 3+ lobsters became more abundant with time. The reasons for the disparity are unknown, but clearly sufficient site replication is needed if juvenile year-class strengths are to reflect settlement patterns accurately. Where pueruli are numerous enough to register on collectors, crevice collectors appear to be more accurate and cost-effective in following recruitment highs and lows than dive surveys.


2015 ◽  
Vol 66 (3) ◽  
pp. 213 ◽  
Author(s):  
R. W. Bradford ◽  
D. Griffin ◽  
B. D. Bruce

The phyllosoma larva of the southern rock lobster, Jasus edwardsii, is thought to be among the longest larval phases of any planktonic larva, with estimates in the literature ranging from 12 to 24 months. In the present study, we have used an extensive archive of samples (over 2800 samples with 680 phyllosoma) to refine the estimate of the duration of the pelagic phase. The distribution through the year of larval stages suggested that larvae from two separate spawning events were present in any 12-month period. Using regression analysis, we have estimated the duration of the phyllosoma phase to be 547±47.5 days (~18.2±1.6 months). A new model of J. edwardsii phyllosoma development is presented and compared with data on known hatching and settlement patterns. The new model will improve the paramiterisation of stage-specific biophysical models of larval dispersal and regional connectivity, to better inform management of the southern rock lobster fisheries.


2021 ◽  
Author(s):  
◽  
Luke Thomas

<p>Understanding patterns of gene flow across a species range is a vital component of an effective fisheries management strategy. The advent of highly polymorphic microsatellite markers has facilitated the detection of fine-scale patterns of genetic differentiation at levels below the resolving power of earlier techniques. This has triggered the wide-spread re-examination of population structure for a number of commercially targeted species. The aims of thesis were to re-investigate patterns of gene flow of the red rock lobster Jasus edwardsii throughout New Zealand and across the Tasman Sea using novel microsatellite markers. Jasus edwardsii is a keystone species of subtidal rocky reef system and supports lucrative export markets in both Australia and New Zealand. Eight highly polymorphic microsatellite markers were developed from 454 sequence data and screened across a Wellington south coast population to obtain basic diversity indices. All loci were polymorphic with the number of alleles per locus ranging from 6-39. Observed and expected heterozygosity ranged from 0.563-0.937 and 0.583-0.961, respectively. There were no significant deviations from Hardy-Weinberg equilibrium following standard Bonferroni corrections. The loci were used in a population analysis of J. edwardsii that spanned 10 degrees of latitude and stretched 3,500 km across the South Pacific. The analysis rejected the null-hypothesis of panmixia based on earlier mDNA analysis and revealed significant population structure (FST=0.011, RST=0.028) at a wide range of scales. Stewart Island was determined to have the highest levels of genetic differentiation of all populations sampled suggesting a high degree of reproductive isolation and self-recruitment. This study also identified high levels of asymmetric gene flow from Australia to New Zealand indicating a historical source-sink relationship between the two countries. Results from the genetic analysis were consistent with results from oceanographic dispersal models and it is likely that the genetic results reflect historical and contemporary patterns of Jasus edwardsii dispersal and recruitment throughout its range.</p>


2015 ◽  
Vol 66 (7) ◽  
pp. 623 ◽  
Author(s):  
Adrian Linnane ◽  
Shane Penny ◽  
Peter Hawthorne ◽  
Matthew Hoare

Previous movement studies on the southern rock lobster (Jasus edwardsii) have all involved releasing tagged animals at the point of capture. In 2007, 5298 lobsters, in total, were tagged and translocated from an offshore site (>100-m depth) to two inshore sites (<20-m depth) in South Australia. After a period of 735 days, 510 (9.6%) had been recaptured. The majority of translocated lobsters were located within close proximity to the release points, with 306 (60%) having moved <5km. Of the remainder, 133 (26%) were recaptured within 5–10km, with a further 71 (14%) individuals having moved >10km. Movement patterns were highly directional in nature, with individuals consistently travelling in a south-west bearing, regardless of distance moved. In almost all cases, movement was from inshore to offshore sites, with female lobsters travelling significantly further (mean 5.66km ±6.41s.d.) than males (mean 5.02km ±9.66s.d.). The results are consistent with previous large-scale tagging studies of J. edwardsii, which indicated high residency levels but with occasional directed movement by some individuals.


2017 ◽  
Vol 36 (2) ◽  
pp. 511-517 ◽  
Author(s):  
Adrian Linnane ◽  
Lachlan McLeay ◽  
Richard McGarvey ◽  
Annabel Jones

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