Response of rock-lobster populations in the Benguela ecosystem to environmental change — a hypothesis

Pollock, D. E.; Shannon, L. V.

doi:10.2989/025776187784522342

Cited by 31 publications

(16 citation statements)

References 5 publications

(6 reference statements)

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“…Increase in density is expected to lead to reduced food availability and growth, which in turn is generally considered to reduce SOM (Breen, 1994;Sanchez Lizaso et al, 2000). This pattern has been observed in other Jasus species (J. lalandii (H. Milne Edwards) and J. tristani Holthuis; Beyers and Goosen, 1987;Pollock and Shannon, 1987;Pollock, 1991) and also in Nephrops norvegicus (L.) (Tuck et al, 2000).…”

Section: Discussionmentioning

confidence: 71%

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: Discussionmentioning

confidence: 71%

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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“…(1985) discussed aspects of the influence of large-scale environmental processes on certain fish species in the Benguela system and their implications with respect 25°t o population modelling. Crawford and Shannon (in press), Pollock and Shannon (1987), Crawford et 1910 1920 1930 1940 1950 1960 1970 1980 1990 …”

Section: Methodsmentioning

confidence: 99%

Annual and interannual variability in the South-East Atlantic during the 20th century

Taunton-Clark¹,

Shannon²

1988

South African Journal of Marine Science

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“…Regional variations in moult increment have been ascribed to differences in food availability (Newman and Pollock 1974a, Pollock and Beyers 1981, Pollock 1982 and oxygen depletion of bottom waters (Pollock and Shannon 1987). Although interannual variations in moult increment are well documented (Newman and Pollock 1974a, Pollock 1987, Melville-Smith et al 1995, the causes are not clearly understood (Shannon et al 1992), Moulting in crustaceans usually results in an increase in body size. Kuris and Mager (\975) suggested that this size increase is programmed by the mitotic increase in cell number at Moult Stage DO-DI.…”

Section: /95mentioning

confidence: 99%

“…This implies smaller moult increments in juvenile females (Pollock 1991), which in itself suggests that juvenile growth rates have decreased in tandem with adult growth rates. Pollock (1987) showed, for 1. lalandii, that size at maturity of females is directly related to the mean moult increment of juvenile females, which were mainly influenced by feeding conditions. There is little evidence to indicate that the decrease in Lm measured in the current study is a result of maturity being reached at an earlier age (at the same growth rate) or the selection of fast-growing females by the fishery.…”

mentioning

confidence: 99%

Shrinkage at moulting in the rock lobsterJasus lalandiiand associated changes in reproductive parameters

Cockcroft¹,

Goosen²

1995

South African Journal of Marine Science

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Response of rock-lobster populations in the Benguela ecosystem to environmental change — a hypothesis

Cited by 31 publications

References 5 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

Annual and interannual variability in the South-East Atlantic during the 20th century

Shrinkage at moulting in the rock lobsterJasus lalandiiand associated changes in reproductive parameters

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