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Translocation, sea ranching, and assisted migration are under scrutiny as methods to augment populations so that harvests can be increased or populations can better adapt to changing environmental conditions. Understanding the ecological effects of any such environmental manipulation is critical to its successful application. One potential ecological effect of any type of stock enhancement is the displacement of either resident or released groups such that finding shelter or foraging habitat is adversely affected. This study examined behavioral interactions of resident and translocatedJasus edwardsiirock lobster after an introduction of 1,961 “small pale” phenotypic morphs to an area populated by the resident “large red” phenotypic morph. This translocation was an experimental stock enhancement conducted as part of a larger study to increase the yield and value of the fishery. Most translocated individuals established a home range within a couple of days of release (generally <2), and these ranges were generally less than 1.0 ha in size. Home-range kernels and foraging ranges overlapped between the two morphs, and there was no evidence of avoidance (Jacob's cohesion index 0.01, Z = 1.06, p = 0.28). This case of translocation for stock enhancement between ecotypes had no detectable adverse effect on either the resident or the translocated population, and in this species, stock enhancement could become part of an integrated conservation and harvest optimization strategy. [ABSTRACT FROM PUBLISHER]

Deep-water southern rock lobsters were translocated to inshore reefs harbouring high-market value southern rock lobsters as part of an experimental spatial management strategy to enhance their market traits, growth and post-harvest condition. We assessed the haemolymph condition of deep-water lobsters before and after (over a period of 14 months) translocation for comparison to resident lobsters at the release site using a range of moult and haemolymph indices. Moult indices indicated that deep-water lobsters were of a similar moult stage to resident lobsters before translocation, they moulted earlier than resident lobsters in their new habitat but were of a moult stage similar to resident lobsters when sampled 12 months after translocation. Comparisons of haemolymph parameters included the total haemocyte count, serum protein and electrotypes such as magnesium and potassium, which were all significantly different between deep- and shallow-water lobsters prior to translocation. These populations when sampled 12 months after translocation showed similar concentrations for all haemolymph parameters, suggesting an improved resilience to post-harvest stress in translocated lobsters. Benefits of translocation to inshore areas on the post-harvest condition of deep-water lobsters could be due to improved body condition through the manipulation of habitat and diet but also from the reduced post-capture transport time and stress duration. [ABSTRACT FROM AUTHOR]

The article explores on the spatial and depth variation in shell color for the Tasmanian, South Australian and Victorian fisheries. It notes on using catch sampling data where proportion of red lobsters decreased with depth and is prevalent at depths less than 30 meter (m), whereas paler lobsters are greater in number in the deeper depth ranges. Meanwhile, it cites that catches of pale lobsters from greater depths remain low in these areas. Furthermore, it analyzes on the impact of these shell color variation in lobsters to the commercial industry of Tasmania and Australia.

The article focuses on the study that evaluates the function of passive integrated transponder (PIT) tags for tag reporting rates in a lobster trap fisher. The study aims to lower down the risk of PIT tag ingestion by testing the insertion of PIT tag into the base of the antennae, the base of the walking leg, and the base of the telson. Furthermore, it examines the precision of hybrid-tags that combined a conventional external Tbar tag with a PIT tag, whereby, scanner malfunction is a major issue and further engineering solutions are required.

Translocation is a form of sea ranching and involves shifting animals between regions to increase yield or to address sustainability issues. We used a sex and size structured model with yearly time steps to examine the use of translocation for management of the Tasmanian rock lobster (Jasus edwardsii) fishery, which is a fishery characterized by spatial heterogeneity in biology and depletion through fishing. Cohorts of undersize lobsters were translocated from four sites of origin to four release sites to explore outcomes under a range of growth rates. Results of translocations were contrasted against estimated yield and egg production if the lobsters had been left at their original site. Gains in yield of greater than 100% of existing yield appear possible through many scenarios, although gains were largest when distances between sites were greatest (from SW to NW Tasmania). Short-distance translocations from deep to shallow water have been proposed to alter market traits of lobsters, but gains in yield from this type of operation appear trivial. Egg production was increased at the release site for all scenarios, indicating that translocation could complement the current policy of rebuilding northern egg production. Translocation appears to offer an alternative management option for increasing yield and could be integrated with other spatial management tools such as regional size limits. [ABSTRACT FROM AUTHOR]

Translocation of undersize rock lobsters Jasus edwardsii from low-growth to high-growth areas has been proposed as a method to improve yield and marketability. The economic feasibility of these operations was examined for translocations by either charter vessels or by fishers retaining their sub-legal catch and releasing these on their return trip to port. Benefit was quantified by the increase in revenue relative to leaving lobsters at their original site, less cost for translocating lobsters. Scenarios were considered feasible when costs per kg gain in yield were below that for quota leased through the market. Lower cost fisher translocations appeared feasible except for short distance translocations from deep to shallow water in the same region. Greatest net benefit occurred from long distance translocations between regions with extreme differences in growth (from SW to NW Tasmania). These operations required vessel charter and led to a net state benefit of Australian169,000 per 5-tonne trip, with internal rates of return approaching 400%. Cost per kg gain in catch for these operations was estimated at less than A3/kg and thus substantially less than the current lease price of around A16/kg. The apparent economic feasibility of translocation provides support for pilot-scale trials. [ABSTRACT FROM AUTHOR]

Early juvenile lobsters reared in captivity may loose anti-predator behaviors displayed by their wild counterparts. To test this hypothesis in juvenile spiny lobsters (Jasus edwardsii), we conducted a series of experiments in which recently settled pueruli were reared in captivity under differing levels of predation risk. After one year in captivity, these lobsters were exposed to a predator in a tank or released into the wild to assess their ability to recognize and respond to predation. We found that lobsters raised without predators significantly reduced their movement activity outside shelters when subsequently introduced to a predator compared with juveniles raised with predators (F1,45 = 4.33, p < 0.05). This apparent over-compensation may be necessary for lobsters to learn the appropriate anti-predator response. Lobsters raised without predators and released into the wild displayed the same types of behaviors as resident wild lobsters. Released lobsters spent more time defending and fighting amongst themselves than the wild lobsters (G = 13.006 > χ20.05,2 = 9.488), but they displayed the appropriate anti-predator responses when approached or attacked by a predator. Our results show that juvenile spiny lobsters habituate to the absence of a predator when reared in captivity for long periods, but display an innate ability to recognize and effectively respond to predators when encountered in a hatchery environment or in the wild. [ABSTRACT FROM AUTHOR]

Southern rock lobsters Jasus edwardsii that are about to moult or have recently moulted have reduced market value due to higher mortality in live transport, higher cannibalism and lower meat recovery. Limiting the landing of softer shelled lobsters is desirable to maintain product quality; however, attempts to set closed seasons or to introduce industry self-regulation have been hampered by subjectivity in measuring shell hardness. We evaluated the use of durometers as a tool for collecting objective measurements of shell hardness. Of the ten locations on the exoskeleton that were evaluated, two locations along the lateral suture line of the exoskeleton gave most consistent readings and underwent largest changes through the moult. The effects of several factors on durometer readings were evaluated: sex, temperature (ambient plus elevated 3°C), location (from around the coast), and size. No effect on durometer readings could be detected from any of these factors with the exception of lobster size. A cumulative logistic function fitted to grouped data provides a method for predicting time before or after moulting from durometer readings. Although durometers appear to be a valuable tool for research on closed seasons, there was not sufficient precision for grading of individual lobsters by industry. [ABSTRACT FROM AUTHOR]