This report summarises a stock assessment of ling on the Chatham Rise (LIN 3&4) for the 2021–22 fishing year. The main index of abundance was the trawl survey series as the commercial longline standardised catch per unit effort series was not deemed suitable. The initial biomass was similar to the previous assessment at about 110 040 t; stock status in 2021 was estimated at 56% B0. Projected stock status in 2027 was between 46% and 59% of B0 depending on recruitment and catch assumptions.
The trends of the ling trawl survey biomass and CPUE of commercial longline fisheries on the Chatham Rise (LIN 3&4) were different in the 1990s. Standardisation accounting for spatial and temporal structure of the fisheries and the underlying ling population resulted in a small change compared with the non-spatial longline CPUE trend and an almost identical trend for the survey biomass in the core area. Although spatial standardisation was important, it was not able to reconcile the indices.
This document presents the CRA 1, CRA 3, CRA 4, CRA 5, and CRA 7&8 rapid updates that can be used to guide management decisions of New Zealand red rock lobster Quota Management Areas. For 2022–23, the adjusted vulnerable biomass was 2% above the reference level (BR) for CRA 1, 34–45% for CRA 3, 32% for CRA 4, almost three times BR for CRA 5, and 1.6 times for CRA 7&8. For all stocks, the probability of the spawning stock biomass being above the soft and hard limits in 2022–23 was 1.
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.