Stock assessment
Age- and length-structured population models, CPUE analysis, data preparation, and assessment of data-rich and low-information stocks.
Project areas
Science for better marine decisions
My work connects data, statistical modelling, and fisheries management. Projects range from focused analyses to full stock assessments, management strategy evaluation, ecological risk assessment, and the software needed to make complex science useful.
Management strategy evaluation
Simulation testing of harvest strategies and operational management procedures under uncertainty.
Ecological risk assessment
Spatial assessment of fishing and other threats to protected species, translating complex evidence into clear measures of risk.
Scientific software
Purpose-built statistical models, reproducible workflows, data products, and interfaces for analysts and decision-makers.
Selected outcomes
From difficult questions to usable evidence
Three examples of Quantifish turning complex data and modelling problems into practical capability for assessment, management, and conservation.
International stock assessment
Modernising the southern bluefin tuna operating model
- Management problem
- The legacy operating model made assumptions difficult to communicate, uncertainty grids cumbersome to revise, and new assessment hypotheses costly to implement.
- Quantifish contribution
- Rebuilt the model in modern RTMB software, validated it against the existing implementation, and developed clearer, more flexible likelihood and population-dynamics components.
- Result
- CCSBT participants gained a transparent, extensible platform for stock assessment, uncertainty analysis, and future management procedure evaluation.
Ecological risk assessment
Identifying the threats that matter most for hoiho
- Management problem
- Hoiho were declining across their northern range, but the effects of multiple marine and terrestrial threats differed by place and life stage.
- Quantifish contribution
- Co-developed regional demographic models, a spatial fisheries risk assessment, threat-overlap layers, and projections that tested where reducing mortality could change the trajectory.
- Result
- The assessment identified poor juvenile and adult survival as the central demographic constraint and showed that halving deaths in either group could stabilise the population—sharpening conservation priorities.
Domestic stock assessment
Reassessing CRA 2 with the lobster stock dynamics model
- Management problem
- The 2017 assessment placed CRA 2 below the soft limit, triggering a rebuild. Managers needed an updated, peer-reviewed view of stock status after catch reductions and improved recruitment.
- Quantifish contribution
- Helped develop and apply the LSD model to CPUE, length frequency, sex-ratio, and tag-recapture data, with Bayesian inference and sensitivity testing overseen by the Rock Lobster Working Group.
- Result
- The assessment was approved by the Fisheries New Zealand Plenary and estimated CRA 2 above its reference level, providing an agreed evidence base for subsequent management advice and rapid updates.
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