The spatial analysis of bottom-contacting trawl effort by commercial trawlers within the New Zealand Territorial Sea and 200 n. mile Exclusive Economic Zone (TS+EEZ), in waters open to trawling down to 1600 m depths, is presented in this report, for different time periods during the 1990–2019 fishing years, based on available data. Separate summaries are presented for inshore and deepwater fisheries. A summary of shellfish dredging is also included.
The collection of long term age data is a requirement for countries fishing for Southern Bluefin Tuna. This report describes the age estimation of otoliths collected from the New Zealand longline and recreational fishing sector between 2015 to 2018. A total of 361 otoliths were aged during this project. Age estimates ranged from 2-27 years and as in previous years there were few samples less than 4 years of age. No modal progression of age classes was observed with the age composition data.
The extent of the bottom-contacting trawl footprint in New Zealand waters open to trawling is updated by this report to include the 2018 (1 October 2017 to 30 September 2018) fishing year, where data are available for the commercial inshore (fishing years 2008–2018) and deepwater trawl fisheries (1990–2018). Effort data for other bottom-contacting fishing methods, Danish seine and shellfish dredge, are also summarised by fishery, for 1990 to 2018 (1989–90 to 2017–18).
Age composition of snapper caught by bottom trawl in the SNA 7 area was estimated for the 2019–20 fishing year. A total of 999 otoliths were selected from 25 qualifying landings. The 2015, 2011, and 2008 year classes collectively accounted for 52% of fish landed. Although these year classes will likely be important to the fishery for many years, there was also evidence of high inter-annual recruitment variability. The mean weighted coefficient of variation for the SNA 7 age composition was 21%.
This report presents a stock assessment update for Foveaux Strait dredge oysters (OYU 5) with the inclusion of fishery data from the 2013 to 2016 years and abundance indices up to the February 2017 survey. The report describes the available data, model structure, and model estimates, including current and projected stock status, and recommendations for future work.
An assessment of hake on Chatham Rise is presented for 2019–20. Chatham Rise hake was estimated to be about 55% B0 following an increase in biomass driven by two strong year classes and low exploitation rate. If catches remain at their recent level, and no long-term reduction in recruitment occurs, then the stock is predicted to continue to rebuild.
Observer data were used to assess the species composition of the New Zealand tuna longline fisheries and to estimate CPUE and the number of fish caught by observed vessels during 2015–16 to 2017−18 fishing years, and added this to the time series from 1989–90. Data were summarised by fishing fleet and area. Reported catches are presented. Discard practices and life status are summarised for the main non-target species.
New Zealand Gamefish Tagging Programme release and recapture data are updated to include the fish tagged and recaptured during the 2019–20 sport fishing year, July–June. The number of gamefish landed by New Zealand Sport Fishing Council clubs is recorded. The combined data from these sources provides a reasonably complete record of recreational catch of billfish and mako and blue sharks. Government Covid-19 restrictions prohibited recreational fishing from boats from late March to May 2020.
This report details the 2020 in LIN 7WC, using the Bayesian stock assessment method. The Deepwater Fisheries Assessment Working Group chose a base case model to assess this stock that incorporated all relevant biological parameters, commercial catch histories, observer data, market sampling data, and research trawl survey data. Four models were developed to evaluate the sensitivity to various hypotheses regarding natural mortality input values and using different indices of abundance.