5 resultados para Size-at-maturity

em Deakin Research Online - Australia


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While Australian firms have generally recognised the value of continuous improvement (CI) in improving performance, many have yet to develop systems to ensure that the efforts of the CI program are focussed on issues of strategic importance to the company. In fact, as recognised in operations management generally, CI activities can have a significant impact on the development of strategy as well as its implementation. The research reported here uses a CI mapping methodology to chart the relationship between CI and strategy in small- to medium-sized manufacturers. Analysis of the link between the firms’ strategies and CI programs indicates that most firms involved in the study made little attempt to link the two and some appear to be unaware of any need to do so. However, such findings seem to be dependent on company size, the maturity of the CI program and the competitive position of the firm. The paper also includes an examination of the role of operations and shopfloor CI in company strategy, particularly as related to SMEs.

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1. Age at maturity is hard to estimate for species that cannot be directly marked or observed throughout their lives and yet is a key demographic parameter that is needed to assess the conservation status of endangered species. 2. For loggerhead turtles (Caretta caretta) in the North Atlantic and North Pacific, juvenile growth rates (c. 10 cm year−1) were calculated by examining size increases during transoceanic journeys; durations of which were estimated from satellite-tracked Lagrangian surface drifter buoy trajectories. 3. Lagrangian-derived growth estimates were used in a weighted loglinear model of size-specific growth rates for loggerhead turtles and combined with newly available information on size at maturity to estimate an age at maturity of 45 years (older than past estimates). 4. By examining the age at maturity for 79 reptile species, we show that loggerhead turtles, along with other large-bodied Testudine (turtle and tortoise) species, take longer to reach maturity than other reptile species of comparable sizes. This finding heightens concern over the future sustainability of turtle populations. By maturing at an old age, sea turtles will be less resilient to anthropogenic mortality than previously suspected.

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Whether spatial variation occurs in the life-history traits of chondrichthyan species is important to fisheries modelling and assessments. A study on the reproductive parameters of Urolophus paucimaculatus from four separate regions across south-eastern Australia found regional differences in maximum total length (TL), size-at-maturity, size-at-maternity and litter sizes. Inshore embayments (Port Phillip Bay (PPB) and Corner Inlet (CI)) appear to allow for larger TLs (females and males) than do offshore areas (Lakes Entrance (LE) and Western Bass Strait (WBS)). Size-at-maturity and size-at-maternity decreased across longitude from west (PPB) to east (LE) and seasonality of parturition and ovulation occurred earlier in PPB (August-October) than in LE (September-December). Maximum litter size correlated with maximum TL (six in PPB, five in each of CI and LE, and four in WBS). There was uncertainty in classifying females for maternal condition because the reproductive cycle appears to range from a continuous annual cycle to a non-continuous biennial cycle. Much of the uncertainty arises from the ambiguity of observation of non-pregnant mature females, which have either aborted through capture and handling, or are in a 'resting year' between pregnancies. Most likely, the majority are reproducing annually with an unknown proportion of females non-continuous and resting between pregnancies.

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Determining the periodicity of the reproductive cycle in chondrichthyan species when the population is recruiting asynchronously, as found for Urolopus viridis, can be problematic. The reproductive cycle generally requires distinguishable trends in reproductive indices across the population. The present study utilised other similar and sympatric urolophid species with synchronous reproductive cycles. Through data collected in the present study and comparisons of maximum total length (TL), periodicity of egg and embryo in utero, ovarian cycles, largest ovarian follicle diameter, and matrotrophic contribution (percentage increase from egg to embryo after maternal histotroph supplement) from similar studies, an annual reproductive cycle can be hypothesised. Sampling across two separate regions of Lakes Entrance (LE) and Western Bass Strait (WBS), U. viridis also showed regionality in several of the reproductive indices. Maximum TL and mass for females, mean size-at-birth, and female size-at-maturity and size-at-maternity in LE were markedly smaller than in WBS. In both regions litter size (1–2) increased with TL, with an exception of one female in WBS producing a litter of 3 which could be attributed to the larger TL. The implication of U. viridis producing such few young annually is they have the lowest biological productivity of any urolophid species in south-eastern Australia.

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This research aimed at discovering the benefits and challenges of integration across a company's e-supply chain. The research involved a single case study of an Australian e-commerce company. In our work, we first formed a framework of benefits and challenges for e-supply chain integration, which was based on the beliefs held by management consultants. After conducting interviews with various organisational stakeholders of an e-commerce company, we found that although some of the elicited opinions matched those expressed by consultants, others provided their refinement in respect to a medium size, rapidly evolving, start-up company. We also discovered challenges, seemingly ignored by the consultants, which concerned changing market conditions and limited economies of scale perceived as seriously impeding SCM integration. Also, the ability to develop and maintain scalable and effective information systems was found to impact the capacity to integrate services across the e-supply chain. The case study's single most important contribution was to bring to our attention the importance of organisational and environmental maturity in the strategic planning of the supply chain management process.