Molt Staging in the Southern Rock Lobster Jasus Edwardsii

Musgrove, Richard

doi:10.1651/0278-0372(2000)020[0044:msitsr]2.0.co;2

Cited by 14 publications

(9 citation statements)

References 18 publications

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“…Moult stage and food ration did have significant effects on BRI ( Table 2). The BRIs of all treatments decreased substantially after moulting and gradually increased throughout the next moult cycle until premoult stage D 1 2 (rationed and starved treatments) and premoult stage D 1 3 (fed treatment) (D 1 2 and D 1 3 refer to two of the seven discrete pleopod moult stages that occur in the premoult period of the moult cycle; see Musgrove 2000). At stages D 1 2-D 1 3 protein levels began to decline slowly as ecdysis approached.…”

Section: Resultsmentioning

confidence: 99%

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Blood refractive index and ratio of weight to carapace length as indices of nutritional condition in juvenile rock lobsters (Jasus edwardsii)

Oliver¹,

MacDiarmid²

2001

Mar. Freshwater Res.

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Nutritional condition reflects food quality and quantity and influences growth rate. Therefore, the ability to measure nutritional condition would be valuable in estimating the potential for growth of captive and wild lobsters. To assess potential indices of nutritional condition, we examined changes in blood refractive index and ratio of weight to carapace length of juvenile rock lobsters to treatments of varying food supply. Blood refractive index was strongly correlated with blood protein concentrations and was a reliable proxy for the circulating protein that is metabolized and diluted during periods of low food and starvation. The moult cycle imposes constraints on blood refractive index, however, so it is essential that the moult stage of the animal be assessed concurrently. Ratios of weight to carapace length were slower to respond to reduced food intake than was blood refractive index but were independent of the moult cycle and may, therefore, be a more direct reflection of nutritional health. These results showed that both blood refractive index and ratio of weight to carapace length are reliable and nondestructive indices of nutritional condition in juvenile rock lobsters.

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Section: Resultsmentioning

confidence: 99%

“…The serum protein concentration was analysed by the biuret method on a Hitachi 917 Random Access Chemistry Analyser. Finally, the distal third of a pleopod was removed with scissors for moult staging according to the pleopod moult-staging criteria described by Musgrove (2000).…”

Section: Methodsmentioning

confidence: 99%

Blood refractive index and ratio of weight to carapace length as indices of nutritional condition in juvenile rock lobsters (Jasus edwardsii)

Oliver¹,

MacDiarmid²

2001

Mar. Freshwater Res.

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“…Colour was assigned following Chandrapavan et al [2] as either ‘Red’ or ‘Brindle (a combination of brindle and white). Basic data on each lobster (carapace length and weight) was recorded and the distal half of one pleopod was cut and kept to determine the moulting stage, following Musgrove [16]].…”

Section: Methodsmentioning

confidence: 99%

Spatial Variability in Condition of Southern Rock Lobsters (Jasus edwardsii) at the Start of the Tasmanian Fishing Season

et al. 2016

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The southern rock lobster (Jasus edwardsii) industry in Australia favours red lobsters, which are usually caught in shallow waters, over paler (brindle) lobsters. This preference is driven partly by the Chinese market, where red is associated with luck and prosperity, and additionally, by the widely held perception within the industry that brindles have greater mortality rates during out of water transport than reds. Limited scientific evidence supports these industry observations; however, these studies did not evaluate the initial condition of lobsters. This study aimed first, to determine which variables better describe condition in J. edwardsii and second, to compare condition among lobsters in several sites around Tasmania at the typical time of high transport mortality. Male lobsters were collected from the South West, South East, East and North coast of Tasmania in late November/December 2014, which correspond to the start of the Tasmanian fishing season. A comprehensive condition assessment was applied by measuring tissue proximal composition, Brix index, Total Haemocyte Count, pH, haemocyanin and another 16 haemolymph parameters of interest. A useful framework to compare condition in J. edwardsii was established by first, using Brix index as a measure of nutritional condition, second, using pH, magnesium, and bicarbonate to evaluate differences in physiological condition and finally, using THC counts as a proxy for lobster health condition. Lobsters from different sites had different nutritional, physiological and health condition, consistent with industry observations, however our results indicate that some red shallow water lobsters exhibited poorer nutritional and health condition, while some deep water brindle lobsters were in good condition. Differences in condition could not be directly associated to catch depth of lobsters and was related to other spatially discrete factors which sometimes vary over distances <3 km.

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“…The clipping of pleopods at the time of first capture and collection of regeneration data on recapture can assist but this is also an imperfect determinant of moulting if the period between release and moulting is too short for regeneration to occur. Guidance on whether the moult is imminent and thus the ability to regenerate is low can potentially be gained from moult staging of the trimmed pleopod [10,22]. The implication for lobster growth research is that pleopod regeneration data provides valuable additional information on whether moulting has occurred and can identify moulting events not apparent from change in size data alone.…”

Section: Discussionmentioning

confidence: 99%

“…Measurement of changes in the exoskeleton between moults has been undertaken through moult-staging of the cuticle [9,10], degree of carapace fouling [11], changes in radiometric isotope composition [12] or shell hardness [13,14]. …”

Section: Introductionmentioning

confidence: 99%

Determination of Moulting Events in Rock Lobsters from Pleopod Clipping

Gardner

Mills

2013

PLoS ONE

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Rock lobster growth is routinely measured for research to optimise management measures such as size limits and quotas. The process of estimating growth is complicated in crustaceans as growth only occurs when the animal moults. As data are typically collected by tag-recapture methods, the timing of moulting events can bias results. For example, if annual moulting events take place within a very short time-at-large after tagging, or if time-at-large is long and no moulting occurs. Classifying data into cases where moulting has / has not occurred during time-at-large can be required and can generally be determined by change in size between release and recapture. However, in old or slow growth individuals the moult increment can be too small to provide surety that moulting has occurred. A method that has been used since the 1970’s to determine moulting in rock lobsters involves clipping the distal portion of a pleopod so that any regeneration observed at recapture can be used as evidence of a moult. We examined the use of this method in both tank and long-duration field trials within a marine protected area, which provided access to large animals with smaller growth increments. Our results emphasised that determination of moulting by change in size was unreliable with larger lobsters and that pleopod clipping can assist in identifying moulting events. However, regeneration was an unreliable measure of moulting if clipping occurred less than three months before the moult.

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Molt Staging in the Southern Rock Lobster Jasus Edwardsii

Cited by 14 publications

References 18 publications

Blood refractive index and ratio of weight to carapace length as indices of nutritional condition in juvenile rock lobsters (Jasus edwardsii)

Blood refractive index and ratio of weight to carapace length as indices of nutritional condition in juvenile rock lobsters (Jasus edwardsii)

Spatial Variability in Condition of Southern Rock Lobsters (Jasus edwardsii) at the Start of the Tasmanian Fishing Season

Determination of Moulting Events in Rock Lobsters from Pleopod Clipping

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