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Charles James Lemckert - One of the best experts on this subject based on the ideXlab platform.
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bottom boundary layer cooling and wind driven upwelling enhance the Catchability of spanner crab ranina ranina in south east queensland australia
Fisheries Oceanography, 2019Co-Authors: David Spencer, Ian W Brown, Shing Yip Lee, Mark J Doubell, Christopher J Brown, Ana Redondo Rodriguez, Hong Zhang, Charles James LemckertAbstract:Abstract Species Catchability is an important parameter used to help optimise stock assessment modelling and the economic efficiency of commercial fishing operations. Previous studies have shown several physical oceanographic parameters, including ambient temperature, waves and currents, affect the Catchability of spanner crabs (Ranina ranina) throughout the Indo-Pacific. Most notably in the Australian fishery, where oceanographic processes vary over space and time, a positive relationship between bottom boundary layer temperature (BBLT) and catch rates was observed. Here, we aimed to better understand how localised oceanographic processes affected this relationship in the southernmost South-East Queensland (SEQ) sector of the Australian fishery at seasonal and short temporal scales. Our results show cooler BBLT, upwelling-favourable alongshore wind stress and increased catch rates occurred during mating season in austral spring. At the end of austral summer, BBLT began warming, downwelling-favourable winds were dominant, and catch rates declined around the post-moult period. Outputs from the generalised linear models (GLMs) that separated these effects in each season show that, at shorter temporal scales, daily catch rates also increased with episodic BBLT cooling and upwelling-favourable alongshore wind stress, but only during austral autumn and winter. These new findings suggest that region-specific, short-term and seasonal variability of oceanographic processes responsible for changes in BBLT play an important role in influencing the Catchability of spanner crabs. We suggest that the effects of region-specific physical oceanographic processes must be considered in future work when investigating the Catchability of commercially important fisheries species fished over large spatial domains.
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physical oceanographic processes affecting Catchability of spanner crab ranina ranina a review
Fisheries Research, 2017Co-Authors: David Spencer, Ian W Brown, Shing Yip Lee, Charles James LemckertAbstract:This review examines the influence of physical oceanographic processes on Catchability of spanner crab (Ranina ranina) in northeast Australia. Physical oceanographic processes may affect crab Catchability by influencing their activity levels and ability to detect bait. Bottom temperature, current velocity, and swell intensity appear to influence catches of spanner crab. At this stage, it appears warmer temperatures enhance Catchability of spanner crab. Spanner crabs were more catchable in stronger currents, and crabs were observed to arrive from down-current of baited traps. However, a decline in catch was observed following periods of intense swell. Data derived from Waverider buoys suggest that occasionally these periods create strong wave-induced seabed current velocities, lead to at depths of 70 m. The oscillatory motion of wave-induced seabed velocities may cause higher suspended sediment concentrations. These observations corroborate the views of local fishermen that spanner crabs avoid ‘murky’ water. The effect of turbidity on Catchability requires further research. Overall, we advocate that studies employ robust methodologies to measure physical oceanographic processes to accurately predict Catchability. Moreover, large-scale physical oceanographic processes may also play an important role in Catchability of spanner crab; including upwelling, eddies, and the East Australian Current. Integrating physical oceanography and fisheries interactions will considerably benefit commercial fishermen as well as provide valuable information for evidence-based management of these valuable resources.
Craig R. Johnson - One of the best experts on this subject based on the ideXlab platform.
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modelling seasonal Catchability of the southern rock lobster jasus edwardsii by water temperature moulting and mating
Marine Biology, 2004Co-Authors: Philippe E. Ziegler, Stewart Frusher, M Haddon, Craig R. JohnsonAbstract:Seasonal variation in Catchability of legal-sized male and female southern rock lobster Jasus edwardsii in a scientific reserve in south-east Tasmania, Australia, over a 15-month period was described by modelling the effects of water temperature, moulting and mating. Seasonal changes in water temperature described 62% of the variation of Catchability for males, but were a poor predictor of Catchability for females outside winter. Both moulting and mating was highly synchronised, although males and females moulted at different times of the year. This had a significant sex-specific effect on Catchability, because the models developed here indicate that feeding and therefore Catchability is decreased during moulting and mating and followed by an increased food consumption to compensate for the lack of feeding during these periods. Gaussian probability density functions were used to represent the timing and intensity of moulting, mating and subsequent compensation periods, and were combined with the description of seasonal temperature changes. Four Gaussian functions in agreement with independent biological data considerably improved the model fits for the Catchability of males (R2=0.84). Adding a single Gaussian function to the temperature model, representing a combined moulting and mating period, provided a good fit to the variation in Catchability of females (R2=0.90). However, the biological relevance of this model remained unclear during a second period of moulting and mating where empirical observations were missing.
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space time variation in Catchability of southern rock lobster jasus edwardsii in tasmania explained by environmental physiological and density dependent processes
Fisheries Research, 2003Co-Authors: Philippe E. Ziegler, Stewart Frusher, Craig R. JohnsonAbstract:A seasonal Catchability model for the rock lobster Jasus edwardsii, which had been developed previously for a population in a scientific reserve, was applied to Catchability estimates over several years in northern and southern fishing regions off Tasmania, Australia. Catchability was estimated from commercial catch and effort data and fishery-independent estimates of exploitation rates. The seasonal Catchability models describe the effects of water temperature, moulting and mating on Catchability. They suggest that similar environmental and physiological processes underpin seasonal Catchability in the two regions of the fishery, but that the relative importance of these factors varies considerably between the two regions. Physiological processes dominate the pattern of Catchability in the north while water temperature contributes significantly to the model only in the south. Interannual variation in relative Catchability was correlated with density-dependent processes. Full models described 72% of the total variation in Catchability over 6 years in the south and 80% of the total variation over 4 years in the north.
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Catchability of the southern rock lobster Jasus edwardsii. II. Effects of size
Marine and Freshwater Research, 2002Co-Authors: Philippe E. Ziegler, Stewart Frusher, Craig R. Johnson, Caleb GardnerAbstract:For most of the year, the size-frequency distribution of trap-caught southern rock lobster, Jasus edwardsii, reflected size-specific Catchability rather than the size-frequency distribution of the population in a scientific reserve in Tasmania, Australia. The size-frequency distributions of the population on the ground and of lobsters captured in traps were similar only during a few months, typically during moulting and mating. Small males and females were usually under-represented in traps. Catchability generally increased with size, but varied with sex and season. During moulting and mating, size-specific Catchability and relative selectivity of larger animals were similar to or lower than for smaller animals. The relative pattern of Catchability throughout the year was similar for most size classes within each sex. Negative associations between small and large lobsters in traps were stronger in winter than in summer, indicating strong behavioural interactions. These interactions could explain the lower Catchability of smaller lobsters. Relative selectivity estimates using tag-recapture and size-specific Catchability data provided generally similar results.
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Catchability of the southern rock lobster jasus edwardsii i effects of sex season and catch history
Marine and Freshwater Research, 2002Co-Authors: Philippe E. Ziegler, Stewart Frusher, Craig R. Johnson, Caleb GardnerAbstract:Seasonal variation in Catchability of the southern rock lobster Jasus edwardsii, was estimated in a scientific reserve in south-east Tasmania by comparing estimates of lobster density based on direct visual observations underwater with concomitant estimates from trapping surveys. Underwater density estimates of undersized and legal-sized male and female lobsters >80 mm carapace length, did not change significantly over the 14-month study period, with the exception of undersized males (≤110 mm carapace length). Sex ratios remained constant at approximately 1:1. In marked contrast, catch rates of males and females and the sex ratio of trapped lobsters varied strongly with season, implying that Catchability varies seasonally and with sex. Catchability of males and females was highest in early summer and lowest in winter. Impact of capture on subsequent Catchability appeared to be weak, since the ratios of tagged animals in the population observed underwater generally reflected recapture rates of tagged animals in trap catches. Recapture rates increased with size and were higher for medium-sized and large males than for similar-sized females. However, for each particular sex-size group, recapture rates remained relatively constant throughout the study period.
David Spencer - One of the best experts on this subject based on the ideXlab platform.
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bottom boundary layer cooling and wind driven upwelling enhance the Catchability of spanner crab ranina ranina in south east queensland australia
Fisheries Oceanography, 2019Co-Authors: David Spencer, Ian W Brown, Shing Yip Lee, Mark J Doubell, Christopher J Brown, Ana Redondo Rodriguez, Hong Zhang, Charles James LemckertAbstract:Abstract Species Catchability is an important parameter used to help optimise stock assessment modelling and the economic efficiency of commercial fishing operations. Previous studies have shown several physical oceanographic parameters, including ambient temperature, waves and currents, affect the Catchability of spanner crabs (Ranina ranina) throughout the Indo-Pacific. Most notably in the Australian fishery, where oceanographic processes vary over space and time, a positive relationship between bottom boundary layer temperature (BBLT) and catch rates was observed. Here, we aimed to better understand how localised oceanographic processes affected this relationship in the southernmost South-East Queensland (SEQ) sector of the Australian fishery at seasonal and short temporal scales. Our results show cooler BBLT, upwelling-favourable alongshore wind stress and increased catch rates occurred during mating season in austral spring. At the end of austral summer, BBLT began warming, downwelling-favourable winds were dominant, and catch rates declined around the post-moult period. Outputs from the generalised linear models (GLMs) that separated these effects in each season show that, at shorter temporal scales, daily catch rates also increased with episodic BBLT cooling and upwelling-favourable alongshore wind stress, but only during austral autumn and winter. These new findings suggest that region-specific, short-term and seasonal variability of oceanographic processes responsible for changes in BBLT play an important role in influencing the Catchability of spanner crabs. We suggest that the effects of region-specific physical oceanographic processes must be considered in future work when investigating the Catchability of commercially important fisheries species fished over large spatial domains.
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physical oceanographic processes affecting Catchability of spanner crab ranina ranina a review
Fisheries Research, 2017Co-Authors: David Spencer, Ian W Brown, Shing Yip Lee, Charles James LemckertAbstract:This review examines the influence of physical oceanographic processes on Catchability of spanner crab (Ranina ranina) in northeast Australia. Physical oceanographic processes may affect crab Catchability by influencing their activity levels and ability to detect bait. Bottom temperature, current velocity, and swell intensity appear to influence catches of spanner crab. At this stage, it appears warmer temperatures enhance Catchability of spanner crab. Spanner crabs were more catchable in stronger currents, and crabs were observed to arrive from down-current of baited traps. However, a decline in catch was observed following periods of intense swell. Data derived from Waverider buoys suggest that occasionally these periods create strong wave-induced seabed current velocities, lead to at depths of 70 m. The oscillatory motion of wave-induced seabed velocities may cause higher suspended sediment concentrations. These observations corroborate the views of local fishermen that spanner crabs avoid ‘murky’ water. The effect of turbidity on Catchability requires further research. Overall, we advocate that studies employ robust methodologies to measure physical oceanographic processes to accurately predict Catchability. Moreover, large-scale physical oceanographic processes may also play an important role in Catchability of spanner crab; including upwelling, eddies, and the East Australian Current. Integrating physical oceanography and fisheries interactions will considerably benefit commercial fishermen as well as provide valuable information for evidence-based management of these valuable resources.
Philippe E. Ziegler - One of the best experts on this subject based on the ideXlab platform.
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modelling seasonal Catchability of the southern rock lobster jasus edwardsii by water temperature moulting and mating
Marine Biology, 2004Co-Authors: Philippe E. Ziegler, Stewart Frusher, M Haddon, Craig R. JohnsonAbstract:Seasonal variation in Catchability of legal-sized male and female southern rock lobster Jasus edwardsii in a scientific reserve in south-east Tasmania, Australia, over a 15-month period was described by modelling the effects of water temperature, moulting and mating. Seasonal changes in water temperature described 62% of the variation of Catchability for males, but were a poor predictor of Catchability for females outside winter. Both moulting and mating was highly synchronised, although males and females moulted at different times of the year. This had a significant sex-specific effect on Catchability, because the models developed here indicate that feeding and therefore Catchability is decreased during moulting and mating and followed by an increased food consumption to compensate for the lack of feeding during these periods. Gaussian probability density functions were used to represent the timing and intensity of moulting, mating and subsequent compensation periods, and were combined with the description of seasonal temperature changes. Four Gaussian functions in agreement with independent biological data considerably improved the model fits for the Catchability of males (R2=0.84). Adding a single Gaussian function to the temperature model, representing a combined moulting and mating period, provided a good fit to the variation in Catchability of females (R2=0.90). However, the biological relevance of this model remained unclear during a second period of moulting and mating where empirical observations were missing.
-
space time variation in Catchability of southern rock lobster jasus edwardsii in tasmania explained by environmental physiological and density dependent processes
Fisheries Research, 2003Co-Authors: Philippe E. Ziegler, Stewart Frusher, Craig R. JohnsonAbstract:A seasonal Catchability model for the rock lobster Jasus edwardsii, which had been developed previously for a population in a scientific reserve, was applied to Catchability estimates over several years in northern and southern fishing regions off Tasmania, Australia. Catchability was estimated from commercial catch and effort data and fishery-independent estimates of exploitation rates. The seasonal Catchability models describe the effects of water temperature, moulting and mating on Catchability. They suggest that similar environmental and physiological processes underpin seasonal Catchability in the two regions of the fishery, but that the relative importance of these factors varies considerably between the two regions. Physiological processes dominate the pattern of Catchability in the north while water temperature contributes significantly to the model only in the south. Interannual variation in relative Catchability was correlated with density-dependent processes. Full models described 72% of the total variation in Catchability over 6 years in the south and 80% of the total variation over 4 years in the north.
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Catchability of the southern rock lobster Jasus edwardsii. II. Effects of size
Marine and Freshwater Research, 2002Co-Authors: Philippe E. Ziegler, Stewart Frusher, Craig R. Johnson, Caleb GardnerAbstract:For most of the year, the size-frequency distribution of trap-caught southern rock lobster, Jasus edwardsii, reflected size-specific Catchability rather than the size-frequency distribution of the population in a scientific reserve in Tasmania, Australia. The size-frequency distributions of the population on the ground and of lobsters captured in traps were similar only during a few months, typically during moulting and mating. Small males and females were usually under-represented in traps. Catchability generally increased with size, but varied with sex and season. During moulting and mating, size-specific Catchability and relative selectivity of larger animals were similar to or lower than for smaller animals. The relative pattern of Catchability throughout the year was similar for most size classes within each sex. Negative associations between small and large lobsters in traps were stronger in winter than in summer, indicating strong behavioural interactions. These interactions could explain the lower Catchability of smaller lobsters. Relative selectivity estimates using tag-recapture and size-specific Catchability data provided generally similar results.
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Catchability of the southern rock lobster jasus edwardsii
2002Co-Authors: Philippe E. ZieglerAbstract:Catchability is estimated indirectly as a 'nuisance' variable in the spatially explicit stock assessment model of the southern rock lobsters Jasus edwardsii in Tasmania, Australia. This study attempted to identify the key mechanisms influencing Catchability to enable direct independent estimates of monthly Catchability. Seasonal variation in Catchability of the southern rock lobster Jasus edwardsii was estimated in a scientific reserve in southeast Tasmania by comparing estimates of lobster density based on direct visual observations underwater with concomitant estimates from trapping surveys. Underwater density estimates of undersized and legal-sized male and female lobsters greater than 80 mm carapace length did not change significantly over the 14 month study period with the exception of undersized males (smaller than 110 mm carapace length). Sex ratios remained constant at approximately 1:1. In marked contrast, catch rates of males and females and the sex ratio of trapped lobsters varied strongly with season, implying that Catchability varies seasonally and with sex. Impact of capture on subsequent Catchability appeared to be weak, since the ratios of tagged animals in the population observed underwater generally reflected recapture rates of tagged animals in trap catches. Size-specific Catchability generally increased with size, but also varied with sex and season. During moulting and mating, size-specific Catchability and relative selectivity did not increase, and sometimes decreased for larger animals. The size-frequency distributions of lobsters captured in traps therefore rarely reflected the size-frequency distribution of the population on the ground. Negative associations between small and large lobsters in traps were stronger in winter than in summer, indicating strong behavioural interactions. These interactions can account for the lower Catchability of smaller lobsters. Relative selectivity estimates using tag-recapture and size-specific Catchability data provided similar results. Seasonal variation in Catchability of legal-sized males and females in the scientific reserve was described by modelling the effects of water temperature, moulting and mating. Seasonal changes in water temperature described 63% of the variation of Catchability for males, but were a poor predictor of Catchability for females outside winter. Both moulting and mating were highly synchronised, although males and females moulted at different times of the year. Gaussian probability density functions were used to represent the timing and intensity of moulting, mating and subsequent compensation periods, and were added to the description of seasonal temperature changes. Four Gaussian functions based on independent biological data considerably improved the model fits for the Catchability of males (R2 = 0.83). However, adding a single Gaussian function to the temperature model, representing a combined moulting and mating period based on independent biological data, provided a less adequate description of the variation in Catchability of females (R2 = 0.49). Only models unconstrained by the observed timing of these events provided a good fit (R 2 = 0.74). The seasonal Catchability models developed for the reserve population were applied to Catchability over several years in two commercially fished regions of Tasmania. Catchability was estimated using commercial catch and effort data and fishery-independent estimates of exploitation rates. The seasonal Catchability models suggest that similar environmental and physiological processes were the main factors determining seasonal Catchability in the two fishery regions, but these factors varied considerably in their relative importance between the two regions. Interannual variation in relative Catchability was correlated with density-dependent processes. Full models described 72% of the overall variation in Catchability over 6 years in the south and 80% of the variation over 4 years in the north. More work is required before direct estimates of Catchability can be included in stock assessment models. In particular, region-specific patterns of seasonal Catchability, and the relationship between density-dependent processes and the interarmual variation in Catchability need to be determined, before Catchability can be reliably predicted in future years and in other regions of Tasmania. Nevertheless, this work has greatly improved our understanding of the processes that apparently underpin seasonal Catchability.
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Catchability of the southern rock lobster jasus edwardsii i effects of sex season and catch history
Marine and Freshwater Research, 2002Co-Authors: Philippe E. Ziegler, Stewart Frusher, Craig R. Johnson, Caleb GardnerAbstract:Seasonal variation in Catchability of the southern rock lobster Jasus edwardsii, was estimated in a scientific reserve in south-east Tasmania by comparing estimates of lobster density based on direct visual observations underwater with concomitant estimates from trapping surveys. Underwater density estimates of undersized and legal-sized male and female lobsters >80 mm carapace length, did not change significantly over the 14-month study period, with the exception of undersized males (≤110 mm carapace length). Sex ratios remained constant at approximately 1:1. In marked contrast, catch rates of males and females and the sex ratio of trapped lobsters varied strongly with season, implying that Catchability varies seasonally and with sex. Catchability of males and females was highest in early summer and lowest in winter. Impact of capture on subsequent Catchability appeared to be weak, since the ratios of tagged animals in the population observed underwater generally reflected recapture rates of tagged animals in trap catches. Recapture rates increased with size and were higher for medium-sized and large males than for similar-sized females. However, for each particular sex-size group, recapture rates remained relatively constant throughout the study period.
Ian W Brown - One of the best experts on this subject based on the ideXlab platform.
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bottom boundary layer cooling and wind driven upwelling enhance the Catchability of spanner crab ranina ranina in south east queensland australia
Fisheries Oceanography, 2019Co-Authors: David Spencer, Ian W Brown, Shing Yip Lee, Mark J Doubell, Christopher J Brown, Ana Redondo Rodriguez, Hong Zhang, Charles James LemckertAbstract:Abstract Species Catchability is an important parameter used to help optimise stock assessment modelling and the economic efficiency of commercial fishing operations. Previous studies have shown several physical oceanographic parameters, including ambient temperature, waves and currents, affect the Catchability of spanner crabs (Ranina ranina) throughout the Indo-Pacific. Most notably in the Australian fishery, where oceanographic processes vary over space and time, a positive relationship between bottom boundary layer temperature (BBLT) and catch rates was observed. Here, we aimed to better understand how localised oceanographic processes affected this relationship in the southernmost South-East Queensland (SEQ) sector of the Australian fishery at seasonal and short temporal scales. Our results show cooler BBLT, upwelling-favourable alongshore wind stress and increased catch rates occurred during mating season in austral spring. At the end of austral summer, BBLT began warming, downwelling-favourable winds were dominant, and catch rates declined around the post-moult period. Outputs from the generalised linear models (GLMs) that separated these effects in each season show that, at shorter temporal scales, daily catch rates also increased with episodic BBLT cooling and upwelling-favourable alongshore wind stress, but only during austral autumn and winter. These new findings suggest that region-specific, short-term and seasonal variability of oceanographic processes responsible for changes in BBLT play an important role in influencing the Catchability of spanner crabs. We suggest that the effects of region-specific physical oceanographic processes must be considered in future work when investigating the Catchability of commercially important fisheries species fished over large spatial domains.
-
physical oceanographic processes affecting Catchability of spanner crab ranina ranina a review
Fisheries Research, 2017Co-Authors: David Spencer, Ian W Brown, Shing Yip Lee, Charles James LemckertAbstract:This review examines the influence of physical oceanographic processes on Catchability of spanner crab (Ranina ranina) in northeast Australia. Physical oceanographic processes may affect crab Catchability by influencing their activity levels and ability to detect bait. Bottom temperature, current velocity, and swell intensity appear to influence catches of spanner crab. At this stage, it appears warmer temperatures enhance Catchability of spanner crab. Spanner crabs were more catchable in stronger currents, and crabs were observed to arrive from down-current of baited traps. However, a decline in catch was observed following periods of intense swell. Data derived from Waverider buoys suggest that occasionally these periods create strong wave-induced seabed current velocities, lead to at depths of 70 m. The oscillatory motion of wave-induced seabed velocities may cause higher suspended sediment concentrations. These observations corroborate the views of local fishermen that spanner crabs avoid ‘murky’ water. The effect of turbidity on Catchability requires further research. Overall, we advocate that studies employ robust methodologies to measure physical oceanographic processes to accurately predict Catchability. Moreover, large-scale physical oceanographic processes may also play an important role in Catchability of spanner crab; including upwelling, eddies, and the East Australian Current. Integrating physical oceanography and fisheries interactions will considerably benefit commercial fishermen as well as provide valuable information for evidence-based management of these valuable resources.