This document describes the lobster stock dynamics (LSD) model: a size-structured model for developing stock assessments of red rock lobsters (Jasus edwardsii) in New Zealand. The LSD model can be used to develop single-area or multi-area stock assessment models. The model was coded in Stan – a language that was developed specifically for Bayesian inference. This document serves as a reference for the model.

The study summarised diets of top predators in New Zealand waters and estimated the spatial-temporal distribution of many of their prey species caught in inshore fisheries. These were consistent with previous estimates and with existing information and could be used as inputs in other processes such as spatial risk assessment models. Care should be taken for species such as squid or hoki where only the shallow part of their range was included and species groups such as jack mackerel or rattail.

Inshore trawl surveys off the west coast North Island using RV Kaharoa resumed in 2018 after nearly 20 years. Where inshore strata areas now overlap a commercial trawl exclusion zone as part of the Māui dolphin Threat Management Plan they are excluded from the new survey area. Historical survey data were analysed to assess the impact of these changes on the ability to monitor adult biomass of target species. The utility of the time series was reviewed for target and some non-target species.