Tied factor analysis for face recognition across large pose differences

Face recognition algorithms perform very unreliably when the pose of the probe face is different from the gallery face: typical feature vectors vary more with pose than with identity. We propose a generative model that creates a one-to-many mapping from an idealized “identity” space to the observed data space. In identity space, the representation for each individual does not vary with pose. We model the measured feature vector as being generated by a pose-contingent linear transformation of the identity variable in the presence of Gaussian noise. We term this model “tied” factor analysis. The choice of linear transformation (factors) depends on the pose, but the loadings are constant (tied) for a given individual. We use the EM algorithm to estimate the linear transformations and the noise parameters from training data. We propose a probabilistic distance metric that allows a full posterior over possible matches to be established. We introduce a novel feature extraction process and investigate recognition performance by using the FERET, XM2VTS, and PIE databases. Recognition performance compares favorably with contemporary approaches

An evaluation of an iterative harvest strategy for data-poor fisheries using the length-based spawning potential ratio assessment methodology

Data on the length structure of exploited stocks are one of the easiest sources of information to obtain for data-poor fisheries, and have the potential to provide cost-effective solutions to the management of data-poor fisheries. However, incorporating the results from stock assessments into a formal harvest strategy, defined here as a harvest management system that incorporates monitoring, assessment, and decisions rules for a specific fishery, usually requires information on the total catch or catch-per-unit effort, data that are not available for many data-poor fisheries. This paper describes and tests a harvest strategy where only length composition data of the catch and knowledge of basic biological parameters are available. The harvest strategy uses a recently developed methodology for stock assessment that estimates the spawning potential ratio (SPR) for an exploited stock from the length structure of the catch (the length-based SPR model; LB-SPR), and uses an effort-based harvest control rule to iteratively drive fishing pressure towards a target level of SPR (40%). A management strategy evaluation framework was used to explore the behaviour of various parameterizations of the harvest control rule for three species with a diverse range of life-histories and M/k ratios ranging from 0.36 (unfished population dominated by large fish) to the Beverton-Holt invariant M/k of 1.5 (unfished population dominated by smaller fish). For all three species the harvest strategy was able to guide the fisheries towards the target SPR, although the time taken for the SPR to stabilise at the target SPR was greatest for the species with the greatest longevity and the lowest M/k. The results of this proof-of-concept study demonstrate that the combination of the LB-SPR assessment model with an iterative, effort-based harvest control rule can successfully rebuild an overfished stock back to sustainable levels or fish down a stock to the target SPR without significantly overshooting the target

Developing a robust new empirically based harvest strategy for gummy shark

The Gummy Shark (GS – Mustelus antarcticus) fishery has lands an annual catch worth approximately $13 million and comprises 15-20% of the value of the South East Shark and Scalefish Fishery (SESSF). The fishery has a long history of stable catches, which successive analyses attribute to recruitment remaining stable since the inception of the targeted fishery in the early 1970s, and there has been little investment in research on the fisheries ecology of Gummy Shark. However, the fishery displays a number of unusual, and poorly understood dynamics, which to some extent are incompatible with standard stock assessment assumptions. An outcome of this project is that it is now clearly understood by Shark Resource Assessment Group (SharkRAG) members that the while Gummy Shark assessment reliably estimates the stable long term trend in recruitment, estimates of adult biomass are poorly informed by data and relatively unreliable. This shared feature of successive GS assessments was of less importance prior to the adoption of the Commonwealth Harvest Strategy Policy and the de facto decision that GS Total Allowable Catches (TAC) would be based on estimates of adult biomass. Since that decision the reliability of estimate of adult GS biomass has become a matter of some importance. The documents prepared and presented through this project to SharkRAG and the South East Management Advisory Committee (SEMAC) and the discussion these documents have supported in those forums, have enabled a shared understanding to be developed of the poor basis estimated adult GS trends provide for setting TACs. The GS assessment model contains virtually no data on adult biomass and consequently model estimates of current adult biomass are largely unconstrained by data. It emerges that the form of Density Dependence Mechanism (DDM) assumed for the assessment model largely determines the estimated trend in adult biomass and current levels, and a wide range of plausible DDMs exist which we have no informed ability to distinguish between. Despite appearances the model has no predictive value with regard the adult biomass trends. This context provides the rationale, and creates the need for, the simpler empirical approach to GS TAC setting documented by this project. With the support of this project, SharkRAG identified that the critical gap in knowledge in this case is quantitative evaluation of the concept and agreed to support the development of collaborative Management Strategy Evaluation (MSE) study aimed at evaluating and developing the proposed empirical harvest strategy for implementation. Through this proposal a collaborative proposal was prepared and revised for Commonwealth Fisheries Research Advisory Board (COMFRAB) on behalf of SharkRAG and involving Biospherics P/L and CSIRO. COMFRAB gave the full proposal a high priority for Australian Fisheries Management Authority (AFMA) funding starting 2011/12

Modelling abalone fisheries

Abalone are valuable marine molluscs which have been exploited for their meaty foot and bowl-like shell by coastal communities since prehistoric times. In modem times it is particularly Japanese and Chinese ethnic groups which value abalone as ebible symbols of prosperity and well-being. Globally the world's abalone fisheries have had a poor management record. In 1969 the annual global production was about 24,000 t per annum compared with today's 12,000 t (FA0 1963-1984). This decline reflects the decline of the Californian abalone fishery which sustained production from last century through to the middle of this century. In recent times the global decline in abalone landings has also been exacerbated by the gradual decline of Japanese landings despite a 16-fold increase in the amount of juvenile abalone artificially produced and seeded into the environment. Today Japan and Australia dominate world production, each producing about 40% of annual production which is worth approximately $200 million in export income to AustraIia’s rural maritime economies. The Japanese pioneered abalone research beginning around the turn of the century and continuing until the present day, reflecting the traditional importance they place upon abalone. During the 1960s and 1970s the Japanese used the techniques of Leslie and Davis (1939) and Delury (1947) to analyse seasonal trends in artisanal catch rates and estimate recruitment trends within wild stock fisheries. Through the rigours of translation their diagnosis seems to have been that the artisanal fishery was recruitment overfishing of abalone stocks but that this exploitation could not be controlled. Consequently Japan appears to have diverted abalone research away from wild stock research and into aquaculture research. Since the 1960s and 1970s general understanding of abalone biology in the west has increased considerably and this has been reflected in the development of models to describe abalone stocks

Gauntlet fisheries for elasmobranchs - The secret of sustainable shark fisheries

The longevity and low fecundity of sharks make them particularly vulnerable to over-exploitation. Previous studies have emphasized the range of natural productivities observed across elasmobranch species and have used this to explain the sustainability of some elasmobranch fisheries and the depletion of others. This paper discusses the assessment of the two principal species fished by the Southern Shark Fishery of Australia, school shark (Galeorhinus galeus) and gummy shark (Mustelus antarcticus). The modeled simulations presented here show that shark behaviour patterns and fishing techniques which restrict fishing mortality to a few juvenile age-classes may be equally or more important than the productivity of different species in determining their relative robustness under exploitation. Counterintuitively concentrating a fishery on a few year-classes of pups, juveniles or sub-adults proves to be a robust management strategy for elasmobranch fisheries, as long as the means exist for protecting adults from fishing mortality. Furthermore this management strategy proves to be most effective with the species considered to be least productive, those with greatest longevity. The obverse of this finding is to highlight the damaging impact on elasmobranch fisheries of human activities such as by-catch, finning, sport fishing and beach protection that cause even low levels of adult mortality

Sustainability requires change to allocated property rights: The story of abalone

Abalone fisheries in Australia and New Zealand are managed at scales of 100s of kilometers with zonal Legal Minimum Lengths (LML) and Individual Transferable Quotas (ITQ), for commercial divers, and short fishing seasons, trip and possession limits for the recreational sector. Abalone resources are comprised of many independent populations which vary widely in their size of maturity. Under focused fishing pressure local populations with larger sizes of maturity have relatively little of their breeding stock protected by a zonal LML. Populations with a large size of maturity relative to the zonal LML are prone to local extinction. A gardening approach to abalone management would allow cultivators to learn optimal shell sizes and harvest rates for individual reefs while allowing government agencies to withdraw into the role of regulator and advisor. Optimizing abalone production necessitates changing the nature of existing property rights from an allocation of zonal catch (ITQ), into a right to harvest a defined area; Territorial User Rights Fishery (TURF). Among the institutional impediments to this reform are the complex allocation issues involved. The first concerns the mechanism by which agencies and stake holders could agree to change existing commercial allocations into an equitably proportional allocation of the harvestable area. Two proposed mechanisms illustrate the essential elements required; equity, transparency and independence from outside influence. The second issue concerns allocation between the commercial sector, recreational and traditional harvesters, and non-extractive users. The current systems generally avoid explicitly allocating shares between these sectors TURF management necessitates making this allocation explicit

The Bare-foot Ecologist’s Toolbox

Updating the Fishing Principle: • Give a person a fish and they are fed for one day. • Teach a person to fish and they are fed for life. • Enable a village to fish sustainably and they are fed for generations. Reaching the end of fisheries ecology doctorate on Haliotids I looked around and saw the seas, particularly coastal and tropical seas, full of small (1-50 km2) stocks. Extremely valuable to local communities in aggregate, Micro-stocks are myriad and complex to study, assess and manage sustainably. It was depressing; how could we ever hope to address the research and management needs of so many small resources. In the 1950s China faced a similar looking national health problem. They responded with bare-foot doctors, not top-end surgeons and technocrats, but low cost, generalist, medical practitioners trained to go out and deal with all the basic village ailments. Micro-stocks need assessment and management at local scales to prevent component stocks suffering the tragedy of commons. Community based and Territorial Rights based systems will prove essential for sustaining these resources. But who will service the technical needs of all these communities of stakeholders? Certainly not the existing Universities and Government Agencies funded by shrinking central governments! When the late Dr Philip Slucanowski and I asked ourselves these questions the only answer was - Bare-foot Ecologists. Embodying the spirits of Johannes and Pauly, and equipped with a tool box borrowed from Walters, bare-foot ecologists would be appropriately trained quantitative, ethno-fisheries ecology generalists, with a love for life, and insatiable curiosity. As with China’s bare-foot doctor campaign, local people trained and equipped to return to local communities will always be far more effective, than visiting foreign experts. Like the famous Hitch-Hiker’s Guide to the Galaxy, the Bare-foot Ecologist’s Toolbox will be a hand-held computer designed to be useful in every situation, as long as user does not panic! Armed with this thought and a working knowledge of the Walters’ personal toolbox Philip and I set out to design the Toolbox

A simple length-structured model based on life history ratios and incorporating size-dependent selectivity: application to spawning potential ratios for data-poor stocks

Selectivity in fish is often size-dependent, which results in differential fishing mortality rates across fish of the same age, an effect known as "Lee’s Phenomenon". We extend previous work on using length composition to estimate the spawning potential ratio (SPR) for data-limited stocks by developing a computationally efficient length-structured per-recruit model that splits the population into a number of subcohorts, or growth-type-groups, to account for size-dependent fishing mortality rates. Two simple recursive equations, using the life history ratio of the natural mortality rate to the von Bertalanffy growth parameter (M/K), were developed to generate length composition data, reducing the complexity of the previous approach. Using simulated and empirical data, we demonstrate that ignoring Lee’s Phenomenon results in overestimates of fishing mortality and negatively biased estimates of SPR. We also explored the behaviour of the model under various scenarios, including alternative life history strategies and the presence of size-dependent natural mortality. The model developed in this paper may be a useful tool to estimate the SPR for data-limited stock where it is not possible to apply more conventional methods

The facilitation of localised stock management in the Australian abalone fishery through simulation and modelling: People power in the Australian abalone fishery

Abalone (Haliotids) are marine molluscs which occur in high density aggregations on shallow coastal reefs (0-20m) in many parts of the world. Since pre-historic times abalone have been highly prized for their accessibility, large meaty foot muscle and bowl like shell. Today they are highly regarded as a delicacy by people of Chinese and Japanese decent for whom abalone symbolize prosperity. Abalone fisheries have proved prone to overfishing. The large fisheries of California and Mexico have experienced collapses. While landings from the large Japanese fishery have slowly declined over the last three decades. Global production peaked at 27 600 tin 1968 and has since declined to below 12 000 t per annum [1], [2]. Concurrently, the value of abalone as an international commodity has increased greatly since the 1960s partly due to declining supply but also as a result of the growing economic strength of the Asian economies. Today Japan and Australia are the principle suppliers of abalone each supplying approximately 40% of global production. The landed value of abalone in Australian is approximately $AUD200 million per annum and approximately 200 divers are licenced to collect it. Entitlements to collect abalone are extremely valuable changing hands for$AUD1-3 million depending on the state for which the entitlement applies. State governments have been quick to realise the revenue potential of the industry and generally charge divers an annual licence fee of $30 000-$40 000 [3]