Hoki ageing: recommendation of which data to routinely record for hoki otoliths

Comparison of estimated age distributions of WCSI hoki catches, derived using old and new ageing protocols, and catch-at-age data for ling. Objectives 4 and 6

Trawl survey of middle depth species in the Southland and Sub-Antarctic areas, November-December 2000 (TAN0012). Objectives 1 and 2

Estimation of acoustic target strength of hoki using in situ data and swimbladder modelling. Objective 2

Acoustic target strength of hoki. Objective 2

Evaluation of meristic characters for determining hoki stock relationships. Objective 1

Catches, size and age structure of the 1999-2000 hoki fishery

Estimates of the target strength of hoki. Objective 3

Estimation of hoki and middle depth fish abundance on the Chatham Rise using trawl surveys


HOK1999-02 Survey Hoki Chatham Rise Objectives 1, 2 Final

The complexity of the hoki stock assessment model

HOK1999-01 Hoki Objective 2 Final

This report presents additional assessments of hoki, hake and ling stocks using alternative catch histories. The assessments are for both hoki stocks (HOK 1 east, HOK 1 west), the three hake biological stocks (HAK 1 Sub-Antarctic, HAK 4 Chatham Rise, HAK 7 west coast South Island), and the three largest ling biological stocks (LIN 3&4 Chatham Rise, LIN 5&6 Sub-Antarctic, LIN 7 WCSI). Estimates of current stock status generally differed little from the base case model assessments.

 Catch statistics and length and age data of hoki taken from the 2015–16 commercial fisheries are summarised and compared with data from previous years. Biomass indices from research surveys and results from other research on hoki in the last year are also briefly described. These data were used in the hoki stock assessment carried out in 2017 (published separately).

The western stock was estimated to be 40–79% B0 and the eastern stock 44–75% B0 (values are 95% CIs for the base case). Under current catches the eastern and western biomasses are likely to increase slightly over the next five years.

The 24th Chatham Rise trawl survey was carried out 3 January to 2 February 2016. In 2016 the survey area was successfully extended to cover to 800–1300 m depths around the entire Rise. In total 139 stations were completed - 84 core (200–800 m) phase 1, 9 core phase 2 and 46 deep (800–1300 m). The estimates of relative core biomass were hoki 114 514 t (CV 14.2%), hake 1299 t (CV 18.5%) and ling 10 201 t (CV 7.2%). The deep strata provide relative biomass indices for a range of deepwater sharks and other species associated with orange roughy and oreo fisheries. Acoustic indices of mesopelagic fish were higher than in 2014.

An acoustic survey of spawning hoki abundance in Cook Strait was carried out from two industry vessels from 24 July to 2 September 2015. The average estimate of hoki abundance from five accepted snapshots (204 000 t, CV 33%) was 21% higher than the equivalent estimate from 2013. Priors on the acoustic survey proportionality constant q were re-evaluated for both the Cook Strait and west coast South Island survey time-series to reflect recent revisions to hoki target strength estimates.

The western stock is estimated to be 36–69% B0 and the eastern stock 43–78% B0 (values are 95% CIs for the base case). For the western stock recruitment has been near or above average since 2001, except in 2010, 2012 and 2013 when it was likely to have been below average (although this is estimated with high uncertainty). In projections the eastern and western biomasses are likely to remain stable or decline slightly over the next five years.

This report provides estimates of annual levels of individual fish and invertebrate species bycatch in eight fisheries across nine New Zealand Tier-1 deepwater species, for 1990–91 to 2012–13. Commercial catch-effort data were used to scale up rates calculated from the observed fishery. Summary tables detail the annual bycatch and bycatch trend for each species or species group.

Results from the fifteenth Tangaroa summer trawl survey of the Southland and Sub-Antarctic areas carried out from 25 November to 23 December 2012 are given in this report. Biomass estimates and population scaled length frequencies are presented for 12 key species. Catch rate data are presented for hoki, hake and ling and include plots for age classes of hoki. Comparisons with earlier surveys are made. Acoustic data collected on the survey are also presented.

Catch statistics and length and age structure data of hoki from commercial sampling during the 2011–12 fishing year are summarised. Length frequency and catch-at-age data from spawning and non-spawning fisheries are compared with those from previous years. Biomass indices from research surveys and results from other research on hoki in the last year are also briefly described. Details of model structure, results, and yield estimates from the hoki stock assessment carried out in 2012 are published separately.

The 21st annual Chatham Rise trawl survey was carried out 2–28 January 2012. In total 134 stations were completed - 90 core (200–800 m) phase 1, 10 core phase 2 and 34 deep (800–1300 m). The estimates of relative core biomass were hoki 87 505 t (c.v. 9.8%), hake 1292 t (c.v. 14.7%) and ling 8098 t (c.v. 13.8%). Estimated biomass of orange roughy in core and northern deep strata was 5202 t (c.v. 26.7%). Acoustic indices of mesopelagic fish had increased from 2011 and were the highest since 2009.

 Results from the fourteenth Tangaroa summer trawl survey of the Southland and Sub-Antarctic areas carried out from 24 November to 23 December 2011 are given in this report. Biomass estimates and population scaled length frequencies are presented for 12 key species. Catch rate data are presented for hoki, hake and ling and include plots for age classes of hoki. Comparisons with earlier surveys are made. Acoustic data collected on the survey are also presented.

Catches, size, and age structure of the 2009–10 hoki fishery, and a summary of input data used for the 2011 stock assessment.

The 20th annual Chatham Rise trawl survey was carried out from 2 to 28 January 2011. 114 bottom trawl stations were successfully completed comprising 88 core (200–800 m) phase one biomass stations, 2 core phase two stations, 23 deep (800–1300 m) stations, and 1 deep phase two station. The estimate of relative core hoki biomass was 93 904 t (c.v. 14.0%), hake was 1 099 t (c.v. 14.9%), and ling was 7 027 t (c.v. 13.8%).

The 23rd annual Chatham Rise trawl survey was carried out 2–28 January 2014. In total 119 stations were completed - 85 core (200–800 m) phase 1, 2 core phase 2 and 32 deep (800–1300 m). The estimates of relative core biomass were hoki 101 944 t (CV 9.8%), hake 1377 t (CV 15.2%) and ling 7489 (CV 7.2%). Estimated biomass of orange roughy in core and deep strata was 6916 t (CV 37.7%). Acoustic indices of mesopelagic fish were lower than in 2013.

An acoustic survey of spawning hoki abundance in Cook Strait was carried out using two industry vessels from 21 July to 3 September 2013. Seven of the nine completed Cook Strait snapshots met all the pre-survey criteria for estimating hoki abundance. The average hoki abundance estimate in 2013 was 377 000 t – 20% higher than the equivalent estimate from 2011. A single snapshot of Pegasus Canyon on 20 August 2013 gave an estimated abundance for this area of 134 000 t.