Estimating the duration of the pelagic phyllosoma phase of the southern rock lobster, Jasus edwardsii (Hutton)

2015 ◽  
Vol 66 (3) ◽  
pp. 213 ◽  
Author(s):  
R. W. Bradford ◽  
D. Griffin ◽  
B. D. Bruce
Keyword(s):  
Regression Analysis ◽  
Larval Dispersal ◽  
Settlement Patterns ◽  
Rock Lobster ◽  
Planktonic Larva ◽  
New Model ◽  
Larval Stages ◽  
Biophysical Models ◽  
Jasus Edwardsii

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.

Juvenile abundance both mirrors and masks a settlement pulse of the rock lobster Jasus edwardsii

2001 ◽  
Vol 52 (8) ◽  
pp. 1067 ◽  
Author(s):  
John D. Booth ◽  
Dean R. Stotter ◽  
Jeffrey S. Forman ◽  
Elizabeth Bradford
Keyword(s):  
Settlement Patterns ◽  
Cost Effective ◽  
The Other ◽  
Rock Lobster ◽  
Frequency Distributions ◽  
Density Dependent Mortality ◽  
Juvenile Abundance ◽  
Jasus Edwardsii ◽  
Dependent Mortality ◽  
Modal Group

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.

scholarly journals Morphological development of larvae and juveniles of Prochilodus argenteus

2017 ◽  
Vol 47 (4) ◽  
Author(s):  
Irũ Menezes Guimarães ◽  
◽  
Vinícius Augusto Dias Filho ◽  
Ana Helena Gomes da Silva ◽  
Rafael Silva Santos ◽  
...  
Keyword(s):  
Regression Analysis ◽  
Linear Regression Analysis ◽  
The Body ◽  
Morphological Development ◽  
Body Proportions ◽  
Juvenile Phase ◽  
Larval Stages ◽  
Larvae And Juveniles ◽  
Rate Of Increase ◽  
Environmental Importance

ABSTRACT: Prochilodus argenteus is an endemic fish species from the São Francisco River basin that is of high economic and environmental importance. The present study aimed to contribute with information to the taxonomic identification of larvae and juveniles of this species. Larvae , obtained from induced spawning of wild animals, were reared in ponds. Individuals were collected daily and classified into larval stages or juvenile phase. Morphological descriptions and morphometric measurements were performed, together with a piece wise linear regression analysis of the body proportions throughout the development process. Individuals in the preflexion stage had a standard length (SL) of 4.48 to 6.64mm, long to moderate body (BH/SL), small to moderate head (HL/SL), and a small to moderate eye (ED/HL). In the flexion stage, the SL varied from 6.60 to 11.00mm, long to moderate body, moderate head, and small to moderate eye. Larvae in the postflexion stage presented SL of 10.54-19.93mm, moderate body, moderate to big head and small eye. The juvenile phase included specimens with a SL of 18.27 to 42.21mm which presented a moderate to high body, big head and small to moderate eye. Regression analysis showed significant moments of change in rate of increase of the body proportions, presenting a change in the growth pattern from allometry to isometry during the early development.

scholarly journals Population Genetics of the Red Rock Lobster,  Jasus edwardsii

2021 ◽  
Author(s):  
◽  
Luke Thomas
Keyword(s):  
Population Structure ◽  
Gene Flow ◽  
New Zealand ◽  
Genetic Differentiation ◽  
Microsatellite Markers ◽  
Rocky Reef ◽  
Rock Lobster ◽  
Wide Range ◽  
Jasus Edwardsii ◽  
Polymorphic Microsatellite

<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>

Residency and movement dynamics of southern rock lobster (Jasus edwardsii) after a translocation event

2015 ◽  
Vol 66 (7) ◽  
pp. 623 ◽  
Author(s):  
Adrian Linnane ◽  
Shane Penny ◽  
Peter Hawthorne ◽  
Matthew Hoare
Keyword(s):  
Large Scale ◽  
South Australia ◽  
Rock Lobster ◽  
Directed Movement ◽  
Translocation Event ◽  
South West ◽  
Movement Dynamics ◽  
Close Proximity ◽  
Jasus Edwardsii ◽  
Almost All

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.

Industry-Supported Sampling Underpins Temporal Management Policy Change in a Commercial Rock Lobster (Jasus edwardsii) Fishery

2017 ◽  
Vol 36 (2) ◽  
pp. 511-517 ◽  
Author(s):  
Adrian Linnane ◽  
Lachlan McLeay ◽  
Richard McGarvey ◽  
Annabel Jones
Keyword(s):  
Policy Change ◽  
Management Policy ◽  
Rock Lobster ◽  
Jasus Edwardsii
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