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C Gardner - One of the best experts on this subject based on the ideXlab platform.
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predation risk within fishing gear and implications for south australian rock lobster fisheries
PLOS ONE, 2015Co-Authors: Felipe Briceno, Juan Carlos Quiroz, Adrian Linnane, C Gardner, Gretta T. PeclAbstract:Depredation of southern rock lobster (Jasus edwardsii) within fishing gear by the Maori octopus (Pinnoctopus cordiformis) has economic and ecological impacts on valuable fisheries in South Australia. In addition, depredation rates can be highly variable resulting in uncertainties for the fishery. We examined how in-pot lobster predation was influenced by factors such as lobster size and sex, season, fishing zone, and catch rate. Using mixed modelling techniques, we found that in-pot predation risk increased with lobster size and was higher for male Lobsters. In addition, the effect of catch rate of Lobsters on predation risk by octopus differed among fishing zones. There was both a seasonal and a spatial component to octopus predation, with an increased risk within discrete fishing grounds in South Australia at certain times of the year. Information about predation within lobster gear can assist fishery management decision-making, potentially leading to significant reduction in economic losses to the fishery.
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growth rate of adult rock Lobsters jasus edwardsii increased through translocation
Fisheries Research, 2010Co-Authors: Arani Chandrapavan, C Gardner, Bridget S GreenAbstract:Growth rates of southern rock lobster, Jasus edwardsii, decrease from north to south of Tasmania and also decrease with depth. Slow-growing Lobsters from deep-water regions were translocated to shallow-water, inshore areas to examine the potential of translocation to increase yield for the Tasmanian rock lobster industry. Within their first moult, translocated Lobsters increased their growth rates, exceeding that of resident deep-water Lobsters from the original site. Growth of translocated females increased to the extent that it exceeded resident shallow-water females in the first year post-release. The increased growth rate of deep-water southern rock Lobsters after translocation and the magnitude of the growth increments achieved in a short period highlight the plasticity in growth of this species. Growth, and therefore size-at-age, are potentially determined by density effects, food availability or other unidentified environmental factors. Rapid increases in lobster growth achieved through translocation suggest that translocation could be applied to increase the productivity of the fishery.
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surviving a sea change survival of southern rock lobster jasus edwardsii translocated to a site of fast growth
Ices Journal of Marine Science, 2009Co-Authors: Bridget S Green, C GardnerAbstract:Green, B. S., and Gardner, C. 2009. Surviving a sea-change: survival of southern rock lobster (Jasus edwardsii) translocated to a site of fast growth. - ICES Journal of Marine Science, 66: 656-664.In an experiment aimed at increasing the yield and value of the fishery for southern rock lobster (Jasus edwardsii), 1998 pale and slow-growing Lobsters were translocated to sites where Lobsters grow faster naturally and develop higher value market traits. Survival of Lobsters in their new habitat was critical to the viability of this experiment. To estimate survival, the release site was surveyed every 1-3 months for 2 years. Apparent survival of translocated Lobsters was compared with survival of resident Lobsters tagged in a similar period using Cormack-Jolly-Seber modelling on mark-recapture data. Lobster survival was not influenced by size, gender, or origin (translocated or resident) alone. The four most parsimonious models suggested slightly lower apparent survival in translocated Lobsters immediately after release compared with all other Lobsters, but support for these models was weak (∑QAIC c weights 62%). The differences in apparent survival were not likely to be significant because of large variance when averaged over all the models. Apparent survival of newly released translocated Lobsters was 92% (72-98, 95% CI) compared with 97% (95-98, 95% CI) for all other Lobsters. Potential sources of differences in survival are movement from the release site or greater predation on pale Lobsters. Losses of lobster through release mortality were low and unlikely to influence the feasibility of translocation as a tool to enhance the value of the fishery, although it would be prudent to include 5% mortality of translocated Lobsters in future models of translocation feasibility.
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colour variation in the southern rock lobster jasus edwardsii and its economic impact on the commercial industry
New Zealand Journal of Marine and Freshwater Research, 2009Co-Authors: Arani Chandrapavan, Adrian Linnane, C Gardner, David HobdayAbstract:Abstract Southern rock lobster Jasus edwardsii varies in shell coloration throughout southern Australia. Predominantly exported as a live product to Asian markets, price is influenced by colour with prices higher for dark red than paler coloured Lobsters, which are discounted. This paper explores spatial and depth variation in shell colour for the Tasmanian, South Australian and Victorian fisheries using catch sampling data. The proportion of red Lobsters decreased with depth and was prevalent at depths less than 30 m, whereas paler coloured Lobsters dominated the deeper depth ranges. The depth of transition where 50% of Lobsters were classified as red showed a weak trend of increase with latitude from southern Tasmania to northern South Australia. Under quota management, lobster colour was a significant driver of fleet dynamics as fishers target areas of high price per unit. Consequently, catches of pale Lobsters from greater depths remain low despite the high catch rates in these areas. The colour price...
Adrian Linnane - One of the best experts on this subject based on the ideXlab platform.
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predation risk within fishing gear and implications for south australian rock lobster fisheries
PLOS ONE, 2015Co-Authors: Felipe Briceno, Juan Carlos Quiroz, Adrian Linnane, C Gardner, Gretta T. PeclAbstract:Depredation of southern rock lobster (Jasus edwardsii) within fishing gear by the Maori octopus (Pinnoctopus cordiformis) has economic and ecological impacts on valuable fisheries in South Australia. In addition, depredation rates can be highly variable resulting in uncertainties for the fishery. We examined how in-pot lobster predation was influenced by factors such as lobster size and sex, season, fishing zone, and catch rate. Using mixed modelling techniques, we found that in-pot predation risk increased with lobster size and was higher for male Lobsters. In addition, the effect of catch rate of Lobsters on predation risk by octopus differed among fishing zones. There was both a seasonal and a spatial component to octopus predation, with an increased risk within discrete fishing grounds in South Australia at certain times of the year. Information about predation within lobster gear can assist fishery management decision-making, potentially leading to significant reduction in economic losses to the fishery.
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integrating recapture conditioned movement estimation into spatial stock assessment a south australian lobster fishery application
Fisheries Research, 2010Co-Authors: Richard Mcgarvey, Adrian Linnane, John E Feenstra, André E. Punt, Janet M. MatthewsAbstract:Abstract The practical aim of this study was to estimate biomass in two subregions, inshore ( 60 m), for application to rock lobster management. To account for lobster movement between these subregions, movement estimation was integrated into the length-structured stock assessment model. Tagged Lobsters were released inshore and offshore in the mid-1990s. For fitting to these conventional single tag-recoveries, a recapture-conditioned movement rate estimation method was adapted and integrated into the assessment model. The individually-tailored probabilities of survival during time-at-large and of subsequent capture in each subregion needed to estimate movement rates are provided by the over-arching stock assessment estimator. Calculating a probability specific for each lobster recapture permits the estimator to account for naturally varying times and locations of tag release and recapture. Seasonality of tagged lobster movements indicated that inshore-to-offshore migration occurred predominantly in winter. Yearly movement rates of Lobsters were relatively low. Biomass was approximately 3–4 times higher inshore than offshore. Testing using simulated data confirmed the accuracy of model-integrated recapture-conditioned movement estimates. Using these same simulated data, conventional movement rate estimates, calculated as raw proportions of recaptured Lobsters that moved, were positively biased. Incorporating survival and recovery rates in movement estimation can thus substantially improve the accuracy of movement, and thus biomass, estimates in spatially-resolved stock assessments.
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colour variation in the southern rock lobster jasus edwardsii and its economic impact on the commercial industry
New Zealand Journal of Marine and Freshwater Research, 2009Co-Authors: Arani Chandrapavan, Adrian Linnane, C Gardner, David HobdayAbstract:Abstract Southern rock lobster Jasus edwardsii varies in shell coloration throughout southern Australia. Predominantly exported as a live product to Asian markets, price is influenced by colour with prices higher for dark red than paler coloured Lobsters, which are discounted. This paper explores spatial and depth variation in shell colour for the Tasmanian, South Australian and Victorian fisheries using catch sampling data. The proportion of red Lobsters decreased with depth and was prevalent at depths less than 30 m, whereas paler coloured Lobsters dominated the deeper depth ranges. The depth of transition where 50% of Lobsters were classified as red showed a weak trend of increase with latitude from southern Tasmania to northern South Australia. Under quota management, lobster colour was a significant driver of fleet dynamics as fishers target areas of high price per unit. Consequently, catches of pale Lobsters from greater depths remain low despite the high catch rates in these areas. The colour price...
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movement patterns of the southern rock lobster jasus edwardsii off south australia
New Zealand Journal of Marine and Freshwater Research, 2005Co-Authors: Adrian Linnane, W F Dimmlich, Tim M. WardAbstract:Abstract Movement patterns of the southern rock lobster Jasus edwardsii were determined from 14 280 tag‐recapture events across South Australia between 1993 and 2003. In total, 68% of Lobsters were recaptured within 1 km of their release site and 85% within 5 km. The proportion of Lobsters moving >1 km in marine fishing areas (MFAs) ranged from 13% to 51%. Movement rates were noticeably high in the south‐east and at Gleesons Landing lobster sanctuary off the Yorke Peninsula but patterns of movement differed spatially. In the south‐east, Lobsters moved distances of 100 km from within the sanctuary to sites located on the north‐western coast of Kangaroo Island and the southern end of Eyre Peninsula. In total, 85% of all Lobsters released inside the sanctuary moved distances >1 km. Movement was highest in immature females within most MFAs. Females also remained at large an average of 124 days lon...
Tim Skewes - One of the best experts on this subject based on the ideXlab platform.
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constructing abundance indices from scientific surveys of different designs for the torres strait ornate rock lobster panulirus ornatus fishery australia
Fisheries Research, 2005Co-Authors: Roland Pitcher, Darren Dennis, Tim SkewesAbstract:Abstract Fishery-independent surveys of the ornate rock lobster (Panulirus ornatus) population in Torres Strait were carried out annually from 1989 to 2002 with variation in design and implementation due to logistic and funding constraints. Fixed and random station surveys were modeled separately, and their results were contrasted. As all the survey data contain many zero records, a gamma-based generalized linear model was used for non-zero records and a Bernoulli based model for the probability of encountering a lobster. Abundance indices for fished and recruiting year-classes were then constructed by combining the results from both models. To select an appropriate error model, four alternatives-log-normal, log-gamma, Poisson, and negative binomial-were explored. The results show that a log-gamma model best estimated the non-zero encounter rates. Recruiting (age 1+) Lobsters exhibit a more variable distribution in space; however, for fished (age 2+) Lobsters there is greater temporal variation in the probability of encountering Lobsters. The large-scale pattern of lobster distribution among sampling strata remained unchanged over the survey period. In contrast to the results from the annual fixed station surveys (1989–2002), the models for the stratified random surveys (1989 and 2002) showed that the small-scale patterns in lobster distribution over depth did change between years. This may undermine the suitability of fixed station surveys for the construction of relative abundance indices of the Torres Strait lobster population.
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age structure of panulirus ornatus in two habitats in torres strait australia
Marine and Freshwater Research, 1997Co-Authors: Tim Skewes, Darren Dennis, C R Pitcher, B G LongAbstract:The lobster population in Torres Strait, Australia, is made up of juvenile and sub-adult Lobsters up to two years old (1+ and 2+), with some 3-year-old (3+) male Lobsters. These Lobsters live either on shallow reefs or in the deeper areas between reefs. Intensive surveys of Lobsters in these two habitats showed that 1+ Lobsters live only in the deep habitat, 2+ Lobsters live in the deep habitat and on shallow reefs, and 3+ male Lobsters live mainly on shallow reefs. In the deep habitat, Lobsters were found mainly in areas that had rock and rubble substratum. There may be little movement of Lobsters onto or off the shallow reefs during the winter months and 1+ Lobsters probably recruit onto the shallow reefs soon after the annual breeding migration of 2+ Lobsters out of Torres Strait in early summer.
Jeffrey D Shields - One of the best experts on this subject based on the ideXlab platform.
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histological assessment of the lobster homarus americanus in the 100 Lobsters project
Journal of Shellfish Research, 2012Co-Authors: Jeffrey D Shields, Kersten N Wheeler, Jessica MossAbstract:The emergence of epizootic shell disease in the American lobster (Homarus americanus) has been devastating to the industry in the coastal waters of southern New England. A comprehensive assessment of the disease syndrome, known as the ''100 Lobsters'' Project, was initiated to examine health and physiological parameters among laboratories involved in the research on lobster shell disease. A histological study of the 100 Lobsters was undertaken as part of that assessment. Tissues from 90 Lobsters from Rhode Island and 19 Lobsters from Maine were examined as a general health assessment of the 100 Lobsters. Approximately half the Lobsters from Rhode Island were selected because they had frank epizootic shell disease, whereas none of the Lobsters from Maine exhibited the syndrome. In addition to epizootic shell disease, the histological findings revealed 3 other idiopathic syndromes—necrotizing hepatopancreatitis, idiopathic blindness, and nonspecific granulomas—in higher prevalences in Lobsters from Rhode Island compared with those from Maine. Necrotizing hepatopancreatitis, a newly described disease syndrome in Lobsters, was observed in 15% of the Lobsters from Rhode Island. Idiopathic blindness was present in 54% of the Lobsters from Rhode Island, and 16% of the animals from Maine. This is the first report of the syndrome in Lobsters from Maine. None of the idiopathic syndromes was associated with epizootic shell disease. The detection of multiple disease syndromes such as epizootic shell disease, necrotizing hepatopancreatitis, and idiopathic blindness may be indicative of exposure to environmental stressors in Narragansett Bay, RI.
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pav1 infection in the florida spiny lobster panulirus argus fishery and its effects on trap function and disease transmission
Canadian Journal of Fisheries and Aquatic Sciences, 2012Co-Authors: Donald C. Behringer, Mark J Butler, Jessica Moss, Jeffrey D ShieldsAbstract:The Caribbean spiny lobster (Panulirus argus) supports the most economically valuable fishery in the Caribbean. In Florida, USA, the majority of the catch is landed in traps "baited" with live, sublegal-sized Lobsters that attract other lob- sters due to their social nature. This species is also commonly infected by the pathogenic virus Panulirus argus Virus 1 (PaV1). Here we describe a polymerase chain reaction (PCR) based assessment of the prevalence of PaV1 in the lobster fishery from the Florida Keys. We tested the effect of PaV1-infected Lobsters in traps on catch and on transmission to other trapped, uninfected Lobsters. We found that 11% of the Lobsters caught in commercial traps were positive for the virus by PCR, but none of these animals showed visible signs of disease. We also tested whether healthy Lobsters avoid diseased lob- sters in traps. Traps into which we introduced an infected lobster caught significantly fewer Lobsters than traps containing an uninfected lobster. Moreover, uninfected Lobsters confined in traps with infected Lobsters acquired significantly more PaV1 infections than those confined with uninfected Lobsters. This study demonstrates the indirect effects that pathogens can have on fisheries and the unintended consequences of certain fishery practices on the epidemiology of a marine pathogen.
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transmission of panulirus argus virus 1 pav1 and its effect on the survival of juvenile caribbean spiny lobster
Diseases of Aquatic Organisms, 2008Co-Authors: Mark J Butler, Donald C. Behringer, Jeffrey D ShieldsAbstract:The Caribbean spiny lobster Panulirus argus, an important fisheries species, is host to Panulirus argus virus 1 (PaV1), a lethal, unclassified virus—the first found in any species of lob- ster—prevalent in juvenile Lobsters. We describe a series of laboratory experiments aimed at assess- ing the likely modes of disease transmission, determining the survival of Lobsters relative to each transmission pathway and identifying potential alternate hosts. Given evidence for lower prevalence of PaV1 in large Lobsters, the effect of lobster size on susceptibility was also examined. Results demonstrated that PaV1 can be transmitted to juvenile Lobsters via inoculation, ingestion of diseased tissue, contact with diseased Lobsters and—among the smallest juveniles—through water over dis- tances of a few meters. Contact and waterborne transmission, the most likely modes of transmission in the wild, were less efficient than inoculation or ingestion. Nevertheless, about half of the smallest Lobsters in contact and waterborne trials contracted the disease and died within 3 mo. Other decapods that co-occur with P. argus (e.g. spotted lobster P. guttatus, stone crab Menippe merce- naria, channel crab Mithrax spinosissimus) did not acquire the disease after inoculation with PaV1- infected hemolymph. Our results confirmed that PaV1 is highly infectious and lethal to juvenile P. argus, particularly early benthic juveniles in the wild, and, hence, is a threat to mariculture.
Kevin A. Hovel - One of the best experts on this subject based on the ideXlab platform.
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Behavioral responses to variable predation risk in the California spiny lobster Panulirus interruptus
Marine Ecology Progress Series, 2010Co-Authors: Chad L. Loflen, Kevin A. HovelAbstract:Shelter dwelling and gregariousness are behavioral strategies used by benthic marine organisms to reduce the risk of predator-induced mortality. For spiny Lobsters, the relative and syner- gistic success of shelter dwelling and aggregation in reducing mortality may vary with the perceived risk of predation as well as the availability and size distribution of conspecifics and shelters. We tested how these factors influence antipredator behavior in the California spiny lobster Panulirus interruptus in southern California kelp forests. We measured shelter and lobster characteristics, predator density, relative lobster mortality outside of shelter, and quantified lobster antipredator behaviors in (1) the La Jolla Ecological Reserve (LJER), a marine protected area with high densities of large fishes known to be lobster predators, and (2) the Point Loma kelp forest, a nearby, heavily fished area. Predator densities and the relative mortality of tethered juvenile and adult Lobsters were much higher in the LJER than in Point Loma, as was mean lobster size. In response to higher preda- tion risk, solitary Lobsters in the LJER used shelters more closely scaled to their body size than lob- sters in Point Loma, thereby restricting predator access to shelters. In addition, aggregations of 2 or more Lobsters were more frequent than expected by chance in the LJER, but not in Point Loma. Lobsters in Point Loma commonly were found outside of shelter during the day, whereas no Lobsters ever were observed outside of shelter during daylight hours in the LJER. Overall, our results indicate that California spiny Lobsters modify their antipredatory behaviors with level of predation risk and that behaviors designed to minimize predator-induced mortality are similar between California spiny Lobsters and other spiny lobster species.
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influence of local scale and landscape scale habitat characteristics on california spiny lobster panulirus interruptus abundance and survival
Marine and Freshwater Research, 2007Co-Authors: Thien T Mai, Kevin A. HovelAbstract:For many marine systems, little is known about the effects of habitat structure on ecological processes that dictate population dynamics. This study focused on the effects of habitat structure on behaviour, abundance, and survival of California spiny lobster (Panulirus interruptus Randall) in the Point Loma kelp forest, San Diego, California. Habitat characteristics were quantified in 400-m2 landscapes to determine the role of shelter and understorey kelp characteristics at local (shelter) scales and landscape scales on lobster habitat use. A tethering experiment determined the effects of the presence of understorey kelp on lobster survival. At the shelter scale, Lobsters preferred permanent shelters to ephemeral shelters, but did not respond to shelter size. At the landscape scale, lobster density increased with Pterygophora californica (stipitate kelp) density and decreased with Laminaria farlowii (prostrate kelp) density, but lobster density did not vary with shelter density or dispersion. Lobster size increased with P. californica density in two of three surveys, while lobster size did not vary with L. farlowii density. Lobster relative survival was higher in the presence of understorey kelp than when kelp was absent. We conclude that Lobsters respond to habitat characteristics at local and landscape scales, and that understorey kelp has strong effects on lobster habitat use and survival.
