Does pleopod setation provide a measure of maturity in female southern rock lobsters &lt;i&gt;Jasus edwardsii&lt;/i&gt;?

Gardner, Caleb; Mills, David J.; Frusher, Stewart

doi:10.3989/scimar.2005.69n1123

Cited by 8 publications

(4 citation statements)

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“…Size of females was recorded as carapace length (CL, the distance from the base of the antennal platform to the dorsal, posterior margin of the carapace along the midline). The females were classified as mature based on the development of ovigerous setae on the endopodite of pleopods (Gardner et al, 2005b). In some cases, pleopods had slight development of setae and observers classed these animals as "partially setose"; these were classed as immature for analyses conducted here.…”

Section: Sample Sites and Specimen Collectionmentioning

confidence: 99%

Spatial variation in size at onset of maturity of female southern rock lobster <i>Jasus edwardsii</i> around Tasmania, Australia

et al. 2006

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SUMMARY:The size at onset of maturity (SOM) of female Jasus edwardsii (Hutton, 1875) was estimated at 50 sites around Tasmania, Australia, based on the presence of ovigerous setae. There was a distinct spatial cline with the largest SOM being found at northwestern sites and the smallest at southwestern sites. Variation in SOM between sites was substantial and ranged from 59 mm to 112 mm carapace length. The observed decline in SOM from north to south was the reverse of that described for the same species at similar latitudes in New Zealand, which suggests that SOM in J. edwardsii is regulated by factors in addition to temperature. The effect of density on female SOM was investigated by comparing SOM estimates from two marine reserves with adjacent fished sites; however, there was no evidence of a decline in SOM with increasing density as predicted. A model of SOM predicted by latitude and longitude is described to facilitate spatial modelling of lobster stocks. The substantial and predictable spatial variation in SOM implies that management of this fishery would be improved by incorporating spatial elements, such as regional legal minimum size limits.Keywords: Jasus edwardsii; maturity; rock lobster; reproduction; spatial management. RESUMEN: VARIACIÓN ESPACIAL EN LA TALLA DE INICIO DE MADUREZ EN HEMBRAS DE LANGOSTA, JASUS EDWARDSII, ENTASMANIA, AUSTRALIA. -En 50 sitios alrededor de Tasmania (Australia) se estimó la talla de inicio de madurez sexual (SOM) en hembras de Jasus edwardsii (Hutton, 1875) basándose en la presencia de sedas ovígeras. La mayor SOM fue observada en la región del Noroeste y la talla menor en el Suroeste. La SOM varió entre 59 mm y 112 mm en longitud del caparazón. La disminución en la SOM desde el norte hacia sur fue inversa a la descrita previamente para la misma especie en similares latitudes en Nueva Zelanda. Esto sugeriría que la SOM en hembras de J. edwardsii es regulada por otros factores además de la temperatura. El efecto de la densidad de langostas en la SOM de hembras de J. edwardsii fue comparado usando SOM estimadas a partir de sitios con alta (reservas marinas) y baja densidad (sitios de pesca) de langostas. El incremento en la densidad no disminuyó la SOM como fue previamente predicho. Para mejorar y facilitar los modelos sobre los stocks de langostas, se describe un modelo para predecir la SOM que incorpora la latitud y la longitud como componentes espaciales. Dado que la SOM depende substancialmente y de manera predecible de las variaciones espaciales, el manejo de la pesquería de J. edwardsii podría ser mejorado con la incorporación de componentes espaciales a los planes de manejo, como por ejemplo establecer regionalmente un tamaño límite legal.Palabras clave: Jasus edwardsii, madurez, langosta, reproducción, gestión espacial.

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Section: Sample Sites and Specimen Collectionmentioning

confidence: 99%

Spatial variation in size at onset of maturity of female southern rock lobster <i>Jasus edwardsii</i> around Tasmania, Australia

et al. 2006

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“…The presence of ovigerous setae on female spiny lobsters is often used as a cost-effective diagnostic tool for assessing size at maturity in stock assessment, but has been criticised for having potential bias towards larger estimates of size at maturity if setae are not retained during the moult phase [25][65]. Research using tag-recapture data [65] detected no loss of ovigerous setae in Southern Rock Lobster following moulting. However, the study did identify a seasonal (within year) component to size at maturity estimates, which the authors attributed to factors that may affect catch composition (e.g.…”

Section: Discussionmentioning

confidence: 99%

Spatial and temporal variations in female size at maturity of a Southern Rock Lobster (Jasus edwardsii) population: A likely response to climate change

2019

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The size at which sexual maturity is reached is a key population parameter used to guide the setting of minimum legal size limits in fisheries. Understanding spatial and temporal variations in size at maturity is fundamental to management because the relationship between size at maturity and minimum legal size limits affects the fraction of the mature population biomass that is harvested, and resulting egg production, larval settlement and recruitment. This study measured the size at maturity of female Southern Rock Lobster (Jasus edwardsii) across South Australia between 1991 and 2015 in relation to known oceanographic characteristics, surface and subsurface temperature data, and relative changes in lobster abundance. There was pronounced north to south spatial variation in estimates of size at maturity. Larger average size at maturity was recorded in warmer north-western areas of the fishery relative to the cooler waters of the south-east. Estimates of size at maturity also differed over 25 years across the fishery. However, the nature of temporal responses varied spatially, and were more consistent with variations in surface and subsurface water temperature at local-scales than changes in lobster density. In the well-mixed waters of the north-western, western and south-eastern parts of the fishery, relatively high rates of increase in sea-surface temperature and size at maturity were recorded since 1991, indicating that size at maturity may be responding to ocean warming associated with global climate change. In more central parts of the fishery, contrasting temporal signals in sea-surface temperature (positive) and bottom temperature (negative) indicated increases in upwelling strength over the study period, and formation of a bottom cold pool below a warm surface layer, with corresponding decreases in size at maturity recorded. The spatio-temporal changes in size at maturity measured in this study highlight the need for oceanographic information to be integrated into future stock assessment models to enhance harvest strategy development, allow timely adaptive management decisions and increase the resilience of fisheries to the impacts of climate change.

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“…The potential causes of the stress response in this case include transport, increased temperature at the new site, disorientation upon release, or unfamiliar habitat. Capture and tagging can be ruled out due to the absence of any previously recorded hiatus in reproduction despite years of capture and tagging [39] .…”

Section: Discussionmentioning

confidence: 99%

“…Eggs are attached to the endopodite processes on pleopods by ovigerous setae. The presence of ovigerous setae was used as an indication of maturity [39] , and their absence indicated that animals were incapable of carrying eggs on the abdomen. All lobsters collected from Maatsuyker Is.…”

Section: Methodsmentioning

confidence: 99%

The Good, the Bad and the Recovery in an Assisted Migration

et al. 2010

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BackgroundAssisted migration or translocation of species to ameliorate effects of habitat loss or changing environment is currently under scrutiny as a conservation tool. A large scale experiment of assisted migration over hundreds of kilometres was tested on a morph from a commercial fishery of southern rock lobster Jasus edwardsii, to enhance depleted populations, improve the yield and sustainability of the fishery, and test resilience to a changing climate.Methodology and Principal FindingsApproximately 10,000 lower-valued, pale-coloured lobsters were moved from deep water to inshore sites (2 in Tasmania [TAS] and 2 in South Australia [SA]) where the high-value, red morph occurs. In TAS this was a northwards movement of 1° latitude. Growth was measured only in TAS lobsters, and reproductive status was recorded in lobsters from all locations. Pale females (TAS) grew 4 times faster than resident pale lobsters from the original site and twice as fast as red lobsters at their new location. Approximately 30% of translocated pale lobsters deferred reproduction for one year after release (SA and TAS), and grew around 1 mm yr−1 less compared to translocated pale lobsters that did not defer reproduction. In spite of this stress response to translocation, females that deferred reproduction still grew 2–6 mm yr−1 more than lobsters at the source site. Lobsters have isometric growth whereby volume increases as a cube of length. Consequently despite the one-year hiatus in reproduction, increased growth increases fecundity of translocated lobsters, as the increase in size provided a larger volume for producing and incubating eggs in future years.Conclusions and SignificanceAssisted migration improved egg production and growth, despite a temporary stress response, and offers a tool to improve the production, sustainability and resilience of the fishery.

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Does pleopod setation provide a measure of maturity in female southern rock lobsters <i>Jasus edwardsii</i>?

Cited by 8 publications

References 31 publications

Spatial variation in size at onset of maturity of female southern rock lobster <i>Jasus edwardsii</i> around Tasmania, Australia

Spatial variation in size at onset of maturity of female southern rock lobster <i>Jasus edwardsii</i> around Tasmania, Australia

Spatial and temporal variations in female size at maturity of a Southern Rock Lobster (Jasus edwardsii) population: A likely response to climate change

The Good, the Bad and the Recovery in an Assisted Migration

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