New Zealand Orange Roughy Fisheries and assessments SPRFMO THIRD WORKSHOP - DEEP WATER WORKING GROUP Alistair Dunn 23 May 2017

Overview New Zealand orange roughy stocks Assessments and management A (brief) history Current status Assessments and management Example: Puysegur Assumptions of productivity The role of CPUE, age/length data, trawl surveys, and acoustics MSC Certification

Orange roughy in New Zealand Multiple stocks around New Zealand Managed as several separate stocks But, stock structure not certain

Orange roughy distribution around New Zealand Wide-spread at depths of 700m to 1500m Most abundant 800-1200m

Orange roughy An important fishery in New Zealand Commercially valuable estimated export value NZ$62 Million Current catches are about 8600 t Main fisheries on the Chatham Rise and Challenger Plateau Previously closed fishery in Puysegur about to re-open in the sub-Antarctic

Assessment and status before 2014 F based strategy Used individual (absolute) estimates of acoustic biomass Integrated models attempted … CPUE, egg surveys, and trawl surveys Age and length data Stock status uncertain “Controversial” assessment processes and management responses

Assessments since 2014 Currently assessed using statistical catch-at-age integrated models ORH 3B (North-west Chatham Rise and East & south Chatham Rise) ORH 7A ORH MEC ORH 3B (Puysegur)

Currently not formally assessed Catch limits based on historical catch trends, or CPUE ORH 1 ORH 2A (north) ORH 7B (closed)

Productivity Typically live to a maximum of about 120-130 years. M=0.045y-1 Maturity assumed to be between 23-32 years interpretation of the transition zone on otoliths Spawning fish likely to be older Based on ageing of spawning aggregations 50% of fish spawning range from 32–41 years

CPUE indices CPUE (catch per unit effort) previously used as an index of abundance But Inconsistencies between CPUE and survey indices Strong evidence of hyper-depletion from assessment models CPUE estimates from spawning aggregations on hills difficult to interpret

Acoustic surveys Improvement in survey design and acoustic technologies Multi-frequency and Acoustic-Optical Systems Resulting in improvements in acoustic abundance indices Determination of prior on acoustic q allowed better interpretation of interpretation of relative indices

Stock status Most orange roughy stocks were initially overfished Estimated to be about 750 000 t of orange roughy in New Zealand before fishing Current status of the assessed stocks range from low (MEC) to healthy (Puysegur) 15-50% B0

Stock biomass (SSB) trajectories

Example: Puysuger Stock in the Southern region of New Zealand Stock reduction analysis based on CPUE estimated the stock size at 7% B0 Closed in 1997/98

Example: Puysegur Reliability of the previous assessments not known New approaches to the treatment and inclusion of historical data More robust Higher threshold for data quality Better understanding of orange roughy population dynamics (better methods) New data (2015) included acoustic biomass estimates and associated age data

Example: Puysegur

Example: Puysegur SSB trajectory No evidence from this stock assessment that the stock was ever at 7% B0. Pretty much as expected as soon as the 2015 AF was sited.

Example: Puysegur stock assessment Integrated statistical catch-at-age model (CASAL) Single sex Single area Ages 1-120+ Mature & immature fish Two time periods Non-spawning season fishery Spawning season fishery Fixed M=0.045, steepness=0.75 Length-weight and growth rates assumed from other areas

MPD fits to trawl LF (start of 1993 FY)

Base model: MCMC residuals: biomass Most of each distribution inside +- 2 which is fine.

Base model: MCMC residuals: trawl LF 93

Base model: MCMC: acoustic q prior and posterior Moved to the left a tad – certainly moved.

Base model: MCMC: true YCS

Base model: MCMC: SSB trajectory No evidence from this stock assessment that the stock was ever at 7% B0. Pretty much as expected as soon as the 2015 AF was sited.

Marine Stewardship Council certification NZ orange roughy certified by MSC Certified in December 2016 About 6000 t certified (~70% of total catch) But Large investment by industry and New Zealand Initial MSC pre-assessment in 2013 Followed by a programme of investment to bring the fishery up to standard The certification was objected to and subject to a full hearing with an independent adjudicator

Summary Current assessment using integrated statistical catch-at-age models Relies on age frequency data and acoustic indices Use assumptions of productivity based on data collection on the area of interest or ‘borrowed’ from neighbouring areas Reasonably sophisticated modelling, but these are becoming more ‘standard’ as experience grows Management advice based on harvest control rules from management strategy evaluations