Sustainability of the Western Rock Lobster Fishery: A review of past progress and future challenges

The Western Rock (spiny) Lobster Fishery has 594 boats operating about 57,000 pots. The average annual catch of 11,000 tonnes is valued at around US$150 million. In addition to the commercial catch, recreational fishers take about 600 tonnes a year. Sustainability in this fishery is maintained by analysis of a comprehensive fisheries database, some of which dates back to the 1960s (e.g. catch, effort, length-frequencies, fishery-independent breeding-stock surveys, puerulus settlement monitoring, recreational catch monitoring); an extensive set of management controls (including a limited fishing season and legal minimum and maximum sizes); and an effective compliance program. Effort in the fishery is controlled by input restrictions on the number of pots allowed and number of days fishing, which are implemented after considerable consultation with industry. The principal method of ensuring the sustainability of the fishery is by monitoring the size of the breeding stock, using data from both a commercial at-sea monitoring program and an annual fishery-independent breeding-stock survey. When the breeding stock fell to low levels in the early 1990s, management initiatives succeeded in returning it to what are considered to be safe levels. Catches are currently high, but fishers have acquired sufficient scientific knowledge to understand that catches will fluctuate for environmental reasons and to take this into account in their fishing operations. Environmental effects have been shown to drive the level of settlement in a particular season. These settlement levels are in turn highly correlated with catches three to four years later, which provides a means of predicting future catches and managing the fishery accordingly. There are issues to be considered in assessing the sustainability of this fishery in the future. The fishery may be overly reliant on egg production from the Abrolhos Islands; catching power of the commercial fleet is increasing due to improvements in gear and technological equipment; growth in catches made by the recreational sector are currently unconstrained; pueruli may be harvested for aquaculture in the near future; and regulations protecting the female brood stock more than the male population could lead to reproductive issues. These potential threats are considered to be low, but will need to be monitored. The fishery was awarded Marine Stewardship Council certification in March 2000, the first in the world to receive this imprimatur

Growth rates and survival of western rock lobster (Panulirus cygnus) at twotemperatures (ambient and 23 C) and two feeding frequencies

Wild caught post-pueruli, year one and year two post settlement juvenile western rock lobster, Panuliruscygnus, were held at ambient temperatures (15.6 C to 23.1 C; mean 19.00.07 C) or at 23 C, and fed thesame ration of a formulated pellet diet either once per night, or 3 times per night, over 12 months, todetermine whether elevated temperatures and multiple feeds per night would stimulate growth throughincreased metabolism and feed utilisation without significant negative impacts on survival. Survival of postpueruli(mean 63%) did not differ between ambient and 23 C. Survival of year 1 and 2 juveniles was higher atambient temperatures (pb0.01 ambient: year 1 juveniles, 68%; year 2 juveniles, 88%; 23 C: 57% and 74%,respectively). Feeding frequency did not affect survival of post-pueruli and year 2 juveniles (mean 63%, 81%respectively), but survival was 9% higher for year 1 juveniles fed three times per night (58% versus 67%;pb0.01). All lobsters grew faster at 23 C than at ambient temperatures (pb0.05), with the growth ofpost-pueruli almost doubled at 23 C (weight gain at 23 C versus ambient: post-pueruli, 18 438 % versus 9915 %; year 1 juveniles 259% versus 165%; year 2 juveniles 23% versus 21%). Feed frequency did not influencethe growth of year 1 and 2 juveniles. However, there was an interaction effect of temperature and feedfrequency on post-pueruli where weight and carapace length were significantly higher at ambienttemperatures when post-pueruli were fed three times a day, whereas at 23 C weight and carapace lengthwere significantly greater when fed once per day (pb0.05). Feed intake (g pellet dry matter lobster-1 day-1)of pellet was higher at 23 C for all lobsters (pb0.05), but was the same between lobsters fed 3 times pernight versus once per night. This study has shown that increasing temperatures to 23 C significantlyimproved the growth of P. cygnus post-pueruli without any adverse effects on survival. The faster growthrates exhibited by year 1 and 2 juveniles at 23 C may potentially offset their lower survival by significantlyreducing culture period. There is no benefit of feeding P. cygnus multiple times at night in terms of growthand survival. The implications for P. cygnus culture are that temperatures should be maintained close to 23 Cduring the entire growout period, with due care taken to minimise mortalities through adequate provision offood and shelter. Feeding P. cygnus once daily to excess just prior to dusk to co-incide with nocturnal feedingbehaviour is recommended

Stocking density and shelter type for the optimal growth and survival of western rock lobster Panulirus cygnus (George)

The growth and survival of three size classes of wild caught western rock lobster, Panulirus cygnus (post-pueruli: mean 2.140.07g, 13.20.1mm CL; year1: post-settlement juveniles, 57.11.1g, 38.70.28mm CL; and year2 post-settlement juveniles, mean 138.22.26g, 51.90.25mm CL) were examined at combinations of two stocking densities (post-pueruli: 50 and 100myear1: 11 and 23m2; year2: 10 and 19m2) and two shelter types (a novel rigid plastic mesh shelter or bricks) over a period 6months. Survival of lobsters held at the lower densities (90 95%) was significantly greater than for lobsters held at higher densities (post-pueruli=78%, year1=86%, year2=88%). Post-pueruli survival was significantly higher in tanks with mesh shelters (91.7%) than brick shelters (75.8%) with a similar trend exhibited by year1 and year2 lobsters. Densities tested did significantly affect lobster growth for any size class. Growth of post-pueruli was considerably higher in tanks with mesh shelters (641.7% weight gain; specific growth rate 1.07BWday1) (p<0.05) but there was no difference in the growth of year1 and lobsters between mesh and brick shelters. Feed intake (g pellet dry matter lobster1day1) was not significantly different between densities. This study has shown that P. cygnus is well suited for aquaculture based on the collection and ongrowing of wild caught pueruli, as this species exhibits good survival at high densities (up to 100m2) without adverse effects on growth, and shows captivity-related health problems. We recommend mesh shelters, with stocking densities of 50m2 for post-pueruli and between and 25m2 for year1 and year2 juveniles, to maximise survival and production

EXTRACTION OF VINEYARD MACROSTRUCTURE FROM SUB-OPTIMAL SEQUENCES OF AERIAL IMAGERY

Remote sensing techniques can be used to identify and classify vine properties such as row width, height, cover-fraction, missing segments and leaf area density, providing opportunities to visualise plant vigour as a spatial function of vineyard geography. This information may then be integrated into decision support tools to improve vineyard management practices. An algorithm for identifying vines from a sequence of overlapping aerial images and then estimating their properties is described. The image stacks were obtained from visible and long wave infrared cameras carried by an unmanned aerial vehicle (UAV). Structure from motion (SfM) was used to create 3D thermal and colourised point clouds, from which the underlying topography of the surface terrain was extracted. The surface topographic model was obtained using bounded data query nearest neighbour calculations, which were reduced to computationally manageable levels using Kd-trees that recursively partitioned the point clouds by progressively separating them into binary trees. This allowed the point clouds to be classified in terms of their hue, saturation, surface temperature and height relative to surface topography using Lloyd’s unsupervised k-means clustering. Individual samples were then associated using Gaussian probability density functions normalised by cluster statistics. The algorithm was evaluated against ground truth obtained using aerial data in terms of its accuracy and robustness using a combination of real world conditions that included high shadowing, poor contrast and UAV flight paths and camera settings that delivered sub-optimal SfM performance

Some comments on graduate training for engineers

QUESTIONING the value and adequacy of postgraduate engineering courses as commonly conducted, L. W. W. Morrow in an article in Electrical Engineering for March 1939, pages 118–22, called for a program of investigation of postgraduate training. Solicited comments of some representative industrialists and educators are presented here

An SNP-Based Linkage Map for Zebrafish Reveals Sex Determination Loci

A surprising diversity of mechanisms controls sex determination of vertebrate organisms, even among closely related species. Both genetic and temperature-dependent systems of sex determination have been described in teleost fish. In the common zebrafish model organism, heteromorphic sex chromosomes are not observed, and the potential role of a genetic component of sex determination remains largely unknown. Here we report a genome-wide linkage study of sex determination in zebrafish using a novel SNP genetic map. We identified loci on zebrafish chromosomes 5 (LOD score 7.9) and 16 (LOD score 9.3) governing sex determination as a complex trait, rather than as an XY or ZW genetic system. Each of these loci contains a prominent candidate gene with a conserved role in sex determination across additional species that suggest potential mechanisms of sex determination in zebrafish. The chromosome 5 locus harbors dmrt1, a key gene in sex determination from fruit flies to humans; mutation of the human DMRT1 ortholog is a cause of complete sex reversal of XY individuals. The chromosome 16 locus harbors cyp21a2; mutation of the human CYP21A2 ortholog is one of the more common causes of pseudohermaphroditism. Mutation detection at each of these candidate genes within the zebrafish cross identified hypomorphic variants on the female-associated allele of each locus. The two loci together accounted for 16% of variance of the trait. Interacting environmental cues are likely to be an additional important component of sex determination in zebrafish

Manipulating the Mouse Genome to Engineer Precise Functional Syntenic Replacements with Human Sequence

SummaryWe have devised a strategy (called recombinase-mediated genomic replacement, RMGR) to allow the replacement of large segments (>100 kb) of the mouse genome with the equivalent human syntenic region. The technique involves modifying a mouse ES cell chromosome and a human BAC by inserting heterotypic lox sites to flank the proposed exchange interval and then using Cre recombinase to achieve segmental exchange. We have demonstrated the feasibility of this approach by replacing the mouse α globin regulatory domain with the human syntenic region and generating homozygous mice that produce only human α globin chains. Furthermore, modified ES cells can be used iteratively for functional studies, and here, as an example, we have used RMGR to produce an accurate mouse model of human α thalassemia. RMGR has general applicability and will overcome limitations inherent in current transgenic technology when studying the expression of human genes and modeling human genetic diseases

Hendra Virus Infection Dynamics in Australian Fruit Bats

Hendra virus is a recently emerged zoonotic agent in Australia. Since first described in 1994, the virus has spilled from its wildlife reservoir (pteropid fruit bats, or ‘flying foxes’) on multiple occasions causing equine and human fatalities. We undertook a three-year longitudinal study to detect virus in the urine of free-living flying foxes (a putative route of excretion) to investigate Hendra virus infection dynamics. Pooled urine samples collected off plastic sheets placed beneath roosting flying foxes were screened for Hendra virus genome by quantitative RT-PCR, using a set of primers and probe derived from the matrix protein gene. A total of 1672 pooled urine samples from 67 sampling events was collected and tested between 1 July 2008 and 30 June 2011, with 25% of sampling events and 2.5% of urine samples yielding detections. The proportion of positive samples was statistically associated with year and location. The findings indicate that Hendra virus excretion occurs periodically rather than continuously, and in geographically disparate flying fox populations in the state of Queensland. The lack of any detection in the Northern Territory suggests prevalence may vary across the range of flying foxes in Australia. Finally, our findings suggest that flying foxes can excrete virus at any time of year, and that the apparent seasonal clustering of Hendra virus incidents in horses and associated humans (70% have occurred June to October) reflects factors other than the presence of virus. Identification of these factors will strengthen risk minimization strategies for horses and ultimately humans

A qualitative study of stakeholders' perspectives on the social network service environment

Over two billion people are using the Internet at present, assisted by the mediating activities of software agents which deal with the diversity and complexity of information. There are, however, ethical issues due to the monitoring-and-surveillance, data mining and autonomous nature of software agents. Considering the context, this study aims to comprehend stakeholders' perspectives on the social network service environment in order to identify the main considerations for the design of software agents in social network services in the near future. Twenty-one stakeholders, belonging to three key stakeholder groups, were recruited using a purposive sampling strategy for unstandardised semi-structured e-mail interviews. The interview data were analysed using a qualitative content analysis method. It was possible to identify three main considerations for the design of software agents in social network services, which were classified into the following categories: comprehensive understanding of users' perception of privacy, user type recognition algorithms for software agent development and existing software agents enhancement