Last updated on 24 September 2018
Recommendations to Retailers & Supply Chain
- Monitor fishery and management system for any changes that could jeopardize MSC certification.
- Support ongoing efforts to further mitigate the incidental capture of seabirds and New Zealand fur seals.
- Ensure benthic protected area network coverage is representative of all types of habitat classes.
Last updated on 9 July 2018
A new stock assessment was carried out in 2018 using research time series of abundance indices (trawl and acoustic surveys), proportions at age data from the commercial fisheries and trawl surveys, and estimates of biological parameters (Fisheries New Zealand 2018). The full quantitative stock assessment applied to the New Zealand Hoki stocks is ranked "high quality" by the assessment body (Fisheries New Zealand 2018), and employs state-of-the-art stock assessment methodology (Akroyd et al. 2012). The age-structured CASAL (C++ Algorithmic Stock Assessment Laboratory) model with Bayesian estimation of posterior distributions considers both eastern and western stocks with no mixing of adults (Ministry for Primary Industries 2017).
Major areas of uncertainty noted in the 2018 stock assessment were the stock structure and migration patterns, the split of the 2014, 2015 and 2016 year classes between the eastern and western stocks, and the respective projections (five-year forecasts are conducted as part of the stock assessment procedure), and possible catchability changes in the Sub-Antarctic trawl surveys. There is increased uncertainty associated with the status of the western NZ hoki stock, particularly to a potential decline in the stock indicated by the 2014 and 2016 Sub-Antarctic trawl survey (Ministry for Primary Industries 2017). These declines are interpreted by the model as being due to observational and process error, but if they are reflective of actual changes in biomass, then the western stock status is overestimated. Another trawl survey of the Sub-Antarctic is scheduled for November-December 2018 (Fisheries New Zealand 2018). Assessment reports have advised that, for a number of reasons, the BMSY reference point estimates should be interpreted with caution, and that BMSY is not a suitable management target. This is largely because of the uncertainty associated with underlying elements (see Scientific Advice section).
Also of note is the considerable impact of annual variations in hoki recruitment on the fishery, and assessment reports have suggested a better understanding of the influence of climate and oceanographic conditions on recruitment patterns. These would be very useful for the future projection of stock size (Ministry for Primary Industries 2017). Lastly, there are sources of additional fishing mortality from incidental causes (e.g. burst bags and net damage) that are not incorporated in the assessment; and no information is available on illegal catches (Fisheries New Zealand 2018).
The assessment process and results are transparent, available publicly online, and are peer reviewed. Updated estimates of hoki stock status have been conducted annually until 2018. As of 2019, given the relative healthy state of the stocks, full assessments will be conducted biannually (i.e. 2019, 2021, 2023, etc) although with annual data updates in-between (O’Boyle et al. 2018).
Last updated on 14 August 2018
Scientific advice on Total Allowable Commercial Catch (TACC) is consistent with the degree of confidence in the stock assessment and reflects the uncertainties. Stock assessment is performed by the Hoki Working Group (HWG) under the New Zealand Government's Ministry for Primary Industries (MPI) but they do not make management decisions. Management is conducted by the MPI and the Deepwater Group Limited (DWG Ltd.), the latter is a non-profit company established to represent quota owners' interests in fisheries science and management (Akroyd et al. 2012). Policy has been successful in maintaining the stock at safe levels.
A target biomass reference point is defined at 35-50% of the average spawning stock biomass (35% B0=362,600 tonnes) that would have occurred if had there been no fishing (B0=1,036,000 tonnes). Other biological reference points were set in 2009: the Soft limit, a “biomass level below which a stock is deemed to be overfished or depleted and needs to be actively rebuilt” (Ministry of Fisheries 2008) , is 20% of the average spawning stock biomass (B20%=207,200 tonnes) that would have occurred if had there been no fishing, and is assumed to be Blim; the Hard limit, a “biomass level below which a stock is deemed to be collapsed where fishery closures should be considered in order to rebuild a stock at the fastest possible rate”, is 10% of B0 (Ministry of Fisheries 2008).
BMSY, is estimated at 27% of B0, but is not considered to be a suitable management target for a number of reasons: 1) uncertainty - it assumes perfect knowledge of the current biomass and stock-recruit relationship (which is poor); 2) it requires a highly responsive harvest strategy that adjusts TACCs annually, which is an unlikely scenario; and 3) its close proximity to the soft harvest limit would permit the limit to be easily and potentially frequently breached given circumstances such as periods of low recruitment, like those observed between 1995-2001 for the Western stock . The lower threshold of the 35-50% B0 management goal is more conservative, and is thus regarded as precautionary. (Ministry for Primary Industries 2017).
Scientific advised catch equates to a TACC that in 2018 corresponds to 90,000 tonnes for the western stock (Fisheries New Zealand 2018). In 2015, three TACC options were consulted (160,000, 150,000 or 155,000 tonnes) but a TACC of 150,000 tonnes (60,000 Eastern stock and 90,000 tonnes Western stock) was considered a better conservative and responsive approach (MPI, 2015b MPI (2015c).
Last updated on 7 July 2018
The 2017-2018 spawning stock biomass (SSB) was estimated to be 659,000 tonnes (64%B0), and is considered to be "Very Likely" (>90%) to be at or above the lower end of the target range (B35-50%), "Likely" (>60%) to be at or above the upper end of the target range, and “Exceptionally unlikely” (<1%) to be below the Hard or Soft Limit. Overfishing is “Very Unlikely" (<10%) to be occurring. Last year (2016-2017), biomass estimate was at 59% of B0 (Ministry for Primary Industries 2017). The stock is expected to increase over the next 5 years if recruitment estimates hold true, and given expected future catch levels. The 2011 and 2014 year classes appear to be strong; while the 2015 year class is estimated to be below average. Following a decreasing trend from from 2003 to 2009, fishing intensity (exploitation rate) has been stable at around 0.1 over the last 6 years, but is still only about half of U35% (0.20). Landings for 2016-2017 were 80,400 tons (sum of Western Coast South Island, Puysegur and Sub-Antarctic landings) (Fisheries New Zealand 2018).
Last updated on 14 August 2018
An ecosystem approach to fisheries management is a future objective. The fishing industry is active in promoting sustainability protection measures. They have led iniatives to reduce catches of small fish including reallocation of catch limits between areas, and seasonal and area closures (Ministry for Primary Industries 2017). A management strategy with a target biomass range of 35-50% of virgin biomass is defined for the hoki fishery. The fishing target associated with the lower end of the biomass target range, U35%, is estimated at 0.20 (Fisheries New Zealand 2018).
The TACCs are recommended by the Minister, consistent with the Fisheries Act 1996, and in agreement with the industry. The target for eastern and western areas combined was set at 150,000 tonnes for 2013-2014, 160,000 tonnes for 2014-2015, and back to 150,000 tonnes for 2015-2016 (MPI 2016). The allocation for the eastern stock has consistently been set at 60,000 tonnes since 2010, with the remaining going to the western area. Increased catch allocated to the western stock from 2009-2010 through 2014-2015 was intended to protect juvenile hoki from both stocks occurring in the Chatham Rise, where the majority of hoki from the eastern stock are harvested (MPI, 2013b).
Other management measures include; fishing by vessels only outside the 12-mile Territorial Sea boundary, no fishing by large vessels in the Cook Strait spawning area, and a voluntary prohibition on trawling in the Benthic Protection Areas (BPA) since 2007 (MPI, 2012). A Code of Practice for directed hoki trawling was introduced by the former Hoki Fishery Management Company in 2001 to protect small fish (under 60 cm) and was updated in 2009 to specifically manage four areas of juveniles’ distribution – Hoki Management Areas (HMA). The aim was to improve stock recruitment and it comprises of closed areas to hoki fishing. These are accessible to other species fishing – and move vessels in any area catching more than 20% of juvenile hoki (revised to smaller than 55 cm) (NZG, 2010; MPI, 2012; Akroyd et al, 2012; (Deepwater Working Group Ltd. 2014). The fishing activity in HMAs is monitored by the MPI that provides a quarterly report to industry (MPI, 2014b).
The National Deepwater Plan (5 years duration) was reviewed during 2017. Detailed information on management measures can be found in Annual Operational Plans for Deepwater Fisheries. Core actions for 2017-2018 includes continue auditing fleet and report level of adherence to sub-Quota Management Areas (QMA) catch limits and HMA requirements and respond where non-compliance with sub-QMA catch limits impacts the sustainability of the stock (Ministry for Primary Industries 2017).
New Zealand hoki was first certified by the Marine Stewardship Council (MSC) as sustainable in 2001 and re-certified in 2007 and 2012. Certification includes Eastern and Western stocks. The single condition of the most recent re-certification regards the impact of the fishery in the habitat was closed out by the first surveillance audit. This certificate has been extended from September 2017 till September 2018 and this fishery has been undergoing reassessment as part of the New Zealand Deepwater Group hake, hoki, ling and southern blue whiting fishery.
Last updated on 14 August 2018
Quota limits for the hoki fishery were first introduced in late 1980s, when the New Zealand’s EEZ was declared. Since the 2004-2005 definition of separate catch limits for eastern and western stocks, set TACCs for the western stock have frequently been exceeded, but by smaller and smaller margins since 2009. The partnership between MPI and DWG Ltd. has strengtheedn compliance (Akroyd et al, 2012). Landings for 2017 (80,400 tonnes) were under the 2016-2017 TACC by nearly 10,000 tonnes (sum Western Coast South Island (WCSI), Puysegur and Sub Antarctic landings). WCSI is the most important catch area in the western stock area (66,600 tonnes in 2017-18). For 2016-2017, about 70,000 tonnes were caught from spawning fisheries and the remaining catches in non-spawning fisheries. (Fisheries New Zealand 2018).
Last updated on 9 July 2018
The interaction of the fishery with Protected, Endangered and Threatened (PET) species is not considered to be unacceptable, but the impact is cumulative with other fisheries, so should be monitored carefully. Details about population status and interactions with fisheries are summarized in the MPI's annual environment and biodiversity reviews.
PET seabirds such as sooty shearwater Puffinus griseus (Near Threatened) (Birdlife International 2017) , white capped albatross Thalassarche steadi (Near Threatened) (Birdlife International 2017), Salvin’s Albatross Thalassarche salvini (Vulnerable) (Thalassarche salvini. (Birdlife International 2017) , Buller’s albatross Thalassarche bulleri (Near Threatened) (Birdlife International 2017) , white-chinned Petrel Procellaria aequinoctialis (Vulnerable) (Birdlife International 2017) are by-catch of the hoki fishery. Management of seabird interactions with New Zealand’s commercial fisheries is driven through the Seabird National Plan of Action (NPOA-Seabirds) (Ministry for Primary Industries 2014). Work is ongoing between MPI and industry to reduce the risk of this fishery to key seabird species. A Vessel Management Plan (VMP) is in place to document fish waste management procedures and reduce the interaction with seabirds (Akroyd et al. 2012). Use of seabird scaring devices for all trawlers >28 m in length, i.e. “paired streamer lines”, “bird baffler” or “warp deflector”, while trawling has been mandatory since 2006. Actions for 2017-2018 will be focused on continuing to improve and manage the VMP process, including the expansion of operating procedures regarding best practice and seabird training sessions for crew on bottom longline vessels (Ministry for Primary Industries 2017). The number of seabirds captured in the hoki fishery has been variable in recent years: in 2014-15, estimated seabird captures in hoki trawl fisheries were 416 (95% c.i. 335-518), the highest in the time series since 2002-03. However, the capture rate, at 2.27 birds per each 100 tows observed, was substantially lower than in 2013-14, when total captures were 397 (95% c.i. 335-483), but the capture rate was 3.93. In 2015–2016, estimated seabird captures in hoki trawl fisheries were 238 (95% c.i. 184–311) with a capture rate of 1.4. In the 2016–17 fishing year, 59 seabird captures were observed in hoki trawl fisheries with a capture rate of 2.0 but the estimate of total captures is not yet available (Fisheries New Zealand 2018). The average observed seabird capture rate in hoki trawl fisheries over the last ten years is about 2.36 birds per 100 tows, which is considered a low rate relative to other New Zealand trawl fisheries (Ministry for Primary Industries 2017). Since 2002-03, the six most captured species in hoki fisheries, based on observer data, have been Salvin's, southern Buller's, and NZ white-capped albatross, as well as sooty shearwaters, white-chinned petrels, and cape petrels. The NPOA-Seabirds employs a risk assessment framework to generate quantitative risk scores for seabird species (Ministry for Primary Industries 2016). The hoki fishery is considered to contribute a high level of risk for two of its most captured seabird species, Southern Buller's albatross and Salvin's albatross, which are assessed as being very high risk species in New Zealand fisheries generally (Ministry for Primary Industries 2017). The mean number of annual potential fatalities in bottom trawl hoki fisheires was estimated at 1540 (95% c.i.: 1140–2050) (Richard et al. 2017), the second highest value. Following the implementation of mandatory mitigation measures (scaring devices), average rates of capture for Salvin's and white-capped albatross (which account for 71% of albatross captures in the hoki fishery) decreased (going from 0.61 and 0.26 to 0.20 and 0.21 per 100 tows respectively, over a 4-year period). The capture rate of white-capped albatross shows a decreasing trend since 2005, while longer term trends for Salvin's and Southern Buller's albatross captures in trawl fisheries are less definative (Ministry for Primary Industries 2016) (Ministry for Primary Industries 2017). While mitigation devices appear to have been effective in decreasing the rate of warp strikes, net captures recently have been observed to be increasing, which has driven higher rates of capture particularly for smaller species such as sooty shearwater (Akroyd et al. 2016).
Marine mammals are protected under provisions of the Marine Mammals Protection Act (MMPA) 1978; and the MPI’s National Deepwater Plan (NDP) includes objectives to avoid and minimize the capture of marine mammals. The fishery does not interact with dolphins or whales (Boyd, 2011). New Zealand fur seals Arctocephalus forsteri (Least Concern) (Chilvers and Goldsworthy 2015) and New Zealand sea lions Phocarctos hookeri (Endangered) (Chilvers 2017) , meanwhile, are identified as incidental catches, but are not considered to be threatened by the fishery (Boyd, 2011). Estimated capture rates for fur seal mortalities in the hoki fisheries in the last five years have been below the long term average; in 2015-2016 the mean estimate was 198 animals, equating to a capture rate of 1.2% per fishery tow. Captures of sea lions hoki fishery is rare, no incidental catches were observed in the last four years (Fisheries New Zealand 2018).Detrimental impacts of the fishery on fur seal populations generally are considered unlikely (Akroyd et al. 2012; Ministry for Primary Industries 2016); though potential risk to local populations has been noted (Ministry for Primary Industries 2013); (Ministry for Primary Industries 2016) . Investigation into population-scale impacts of fishery-related fur seal deaths has been limited by uncertainty about the size of the NZ population and the provenance of animals captured ((Ministry for Primary Industries 2016); and until recently, assessment of the overall risk has relied largely on expert opinion and qualitative ecological risk assessment (ERA) (Akroyd et al. 2012); (Ministry for Primary Industries 2016). However, a Spatially Explicit Risk Assessment (SEFRA), already applied to New Zealand seabirds, is currently being completed for marine mammals (Ministry for Primary Industries 2016). Fishery-related risk to fur seals is attributed primarily to trawl fisheries targeting hoki and southern blue whiting; and preliminary SEFRA results estimate a cumulative risk ratio across fisheries to be between 0.2-0.6, on a 0.0-5.0 scale, a result that is considered to be consistent with indications that the population size has been increasing in recent years. To improve understanding of the effects of the commercial fisheries on NZ fur seal populations, recommendations include more consistent population data at different geographic scales, genetic work to differentiate between colonies, and increased observer coverage to improve catch estimates. In 2013 the DWG Ltd., in agreement with industry and NGOs, developed a set of Marine Mammal Operational Procedures (MMOP) for mitigating marine mammal bycatch (Ministry for Primary Industries 2013). Active monitoring of interactions is ongoing (Ministry for Primary Industries 2013); (Ministry for Primary Industries 2016). A Threat Management Plan will be developed for sea lions (Ministry for Primary Industries 2017).
Basking shark Cetorhinus maximus – listed in CITES (Convention on International Trade in Endangered Species of Wild Fauna and Flora) and in the IUCN 2005 Red List as Vulnerable (Fowler 2005) – is occasionally caught as bycatch, although captures have been few since the ealy 2000s (Ministry for Primary Industries 2017, Fisheries New Zealand 2018). The species has had protected status in New Zealand since 2010 (Ministry for Primary Industries 2017). A qualitative risk assessment classified the risk of the impact of commercial fishing on New Zealand as high risk (Ford et al. 2018). There are no direct mitigation measures, though the DWG Ltd. provides guidance on reporting and safe handling practices to help ensure survival upon release (Deepwater Working Group Ltd. 2014). The New Zealand National Plan of Action for the Conservation and Management of Sharks (NPOA–Sharks) (2013) outlines a set of actions for the conservation and management of sharks, which include review of management categories and protection status, addressing research gaps for high-risk species, monitoring of the implementation of the shark finning ban, and work with fishers to ensure best practice handling and mitigation measures (Ministry for Primary Industries 2016). Mandatory reporting of catches of protected species serves to monitor interactions. Some research into the interactions between basking sharks and fisheries has been published (e.g. Francis & Sutton (2012) (Ministry for Primary Industries 2017). The 2017-2018 Annual Operational Plan for deepwater fisheries also mentions additional actions, e.g. improving the identification and reporting of sharks (Ministry for Primary Industries 2017). The last MSC reassessment of the fishery made a recommendation to understand the biological status of all pale ghost shark Hydrolagus bemisi (Least Concern (Francis 2003) ) stocks (Akroyd et al. 2012). Porbeagle Lamna nasus and school Galeorhinus galeus sharks (both Vulnerable (Stevens et al. 2006); (Walker et al. 2006) ) are QMS bycatch species but are not considered to be threatened by the fishery. In addition to species already noted, the second MSC surveillance audit completed in 2014, mentioned other protected species captures reported by observers in the 2012-13 fishing year including dusky dolphin (1) and pilot whale (1) (Akroyd and Pierre, 2014). The current Public Comment Draft Report for the new MSC reassessment for New Zealand hoki, hake and ling trawl fisheries do not attribute any condition or recommendations (O’Boyle et al. 2018).
Many benthic organisms are protected in New Zealand including black corals (all species in the order Antipatharia), Gorgonian corals (all species in the order Gorgonacea), Stony corals (all species in the order Scleractinia), Hydrozoa (hydra-like animals), and Hydrocorals (all species in the family Stylasteridae) (NZ Department of Conservation 2017) . While captures are required by law to be reported, their capture in commercial fisheries is not illegal (Akroyd et al. 2012). While there is a growing body of research on benthic organisms such as corals (Ministry for Primary Industries 2016), robust managment has been limited to a degree by lack of knowledge ((Akroyd et al. 2012). Hoki fisheries presents more observations of catches of protected corals (all species) in comparasion with other deepwater fisheries but the total coral bycatch is typically low (O’Boyle et al. 2018). Data from New Zealand seamounts demonstrated a reduction of stony coral cover on trawled seamounts (average in images 0.04–0.03%) in comparasion with untrawled seamounts (average in images 12–25%) (Clark et al. 2016).
Last updated on 9 July 2018
Hoki was 84.7%, 85.9% and 88% of the catch in 2012-2013, 2013-2014 and 2014-2015 respectively (Ministry for Primary Industries 2017). Data on bycatch and discarded species are obtained through both the recording of catches and observers’ reports. Composition and proportion of commercial and non-commercial species vary between the fishing areas and seasons (Ministry of Fisheries, 2011a).
Main non-target species that are predominantly managed under the Quota Management System (QMS) and are at least 1% of catches are considered as key bycatch species. Species that are not-QMS are usually discarded, incidentally captured and of little commercial value (NDP, 2012). By-catch of non-QMS fish species constitutes a small proportion (<5%) of the total hoki catch (MPI, 2013b). For the all fishing areas and between 2014-2015 (proportion in weight of catches) of main captured species were: hoki (88.0%), ling (2.4%), javelinfish (1.4%), rattails (1.1%) and hake( 1.8%) (Ministry for Primary Industries 2017). None of the captured species is considered to be a concern (Akroyd et al. 2012). Total annual discard estimates ranged from about 5,500 to 29,000 tons per year between 2000–01 and 2006–07 (MPI, 2013). According to Anderson (2014), the species showing the greatest decline in by-catch rate between 1990-2012 were skates, slender jack mackerel and dogfishes. The species showing the greatest increase were floppy tubular sponge (Hyalascus sp.) and umbrella octopus (Opisthoteuthis spp.). However, this increase also could resulted of an improved identification of these species. Any increase to the Hoki TAC (2014/2015 season) is unlikely to have an unacceptable impact on the by-catch species (MPI, 2014b).
Management controls to reduce bycatch and discards include restrictions prohibiting bigger vessels (>45 m) from operating near the coast, agreed catch splits between eastern and western stocks, and measures outlined under Industry Operational Procedures for hoki trawling fisheries aimed at protecting smaller fish (<55 cm) and mitigate bycatch of marine mammals (Deepwater Working Group Ltd. 2014). HMAs contribute when the catch is more than 20% of juveniles (Ballara, 2010; Ministry of Fisheries, 2011; MPI, 2012).
A framework for sustainability risk assessment of fish by-catch in deepwater fisheries in New Zealand is presently under development (Roux et al., 2015). Some recent news shows that this fishery is under strong contestation regarding claims of fish dumping and misreporting, e.g. (Robertson et al. 2018).
Last updated on 14 August 2018
Trawling using demersal or midwater gear is the only method of capture in the directed hoki fishery (Ministry for Primary Industries 2017). Mid-water trawling is expected to occasionally interact with the seabed ecosystem. Midwater trawl was the predominant gear in the early history of the hoki fishery, but bottom trawling has accounted for a greater share of the area-wide effort since the mid-1990s. It dominates heavily on the Chatham Rise and Sub-Antarctic fishing grounds, where it is used outside of the spawning season. THoki-directed trawls have accounted for approximately one third of all tows undertaken in New Zealand deepwater fisheries (O’Boyle et al. 2018). Quantification of the trawling footprint, knowledge of benthic distributions, and assessment of risks of trawling impacts on benthic habitat has been done (Ministry for Primary Industries 2017). The Annual Operational Plan for Deepwater Fisheries 2017/18 includes a Benthic Framework “ Benthic Invertebrates: Monitor and measure the nature and extent of benthic interactions with deepwater fishing activity” (Ministry for Primary Industries 2017).
Past assessments have indicated that generally benthic bycatch is small, except for sponges (Ministry of Fisheries, 2010). Baird et al., (2013) mentioned that although all coral orders were represented in the hoki bycatch, about 80% were stony corals (Baird et al., 2013).
In light of an industry proposal, Benthic Protection Areas (BPAs) within New Zealand’s EEZ were closed to bottom trawling (and dredging) in 2007 on a permanent basis (Deepwater Working Group Ltd. 2015); (Ministry for Primary Industries 2017). There are 17 large BPAs that effectively closed approximately 30% of the New Zealand EEZ (Ministry for Primary Industries 2014), and cover 52% of all seamounts and 88% of hydrothermal vents (New Zealand Department of Conservation and Ministry of Fisheries 2005, Ministry for Primary Industries 2017a, Ministry for Primary Industries 2013a, Ministry for Primary Industries 2014). The Hoki Operational Procedure (HOP) is applied to all vessels greater than 28 m and includes four closing areas to protect juvenile hoki: Cook Start, Canterbury banks, Mernoo Bank and Puysegur Bank (Ministry for Primary Industries 2014). However, recent studies have been assessing New Zealand's existing MPAs and considered that existing MPAs are inefficient in protecting a representative range of biodiversity (Geange et al. 2017).
Some habitat classes – Benthic-Optimised Marine Environment Classification (BOMEC) 7, 8, 9 – were identified in an Ecosystem Risk Assessment conducted by Boyd (2011), and were considered of special vulnerability. Of highest concern was BOMEC class 9 habitat on the heavily trawled Chatham Rise, which was considered to be at "major risk" (Akroyd et al. 2012). BOMEC classes 7 and 8 were considered "moderate risk" in some areas, but were later downgraded to "negligible risk". Identification of unprotected BOMEC 9 habitat in the Chatham rise has prompted question by some stakeholders as to whether BPAs are represenative enough. The MSC re-certification of the fishery (achieved in 2012) defined one condition: “Improve management of habitat impacts of the hoki fishery, such that by the end of third surveillance audit, it can be shown that the fishery is highly unlikely (i.e. there should be no more than a 30% probability) to reduce habitat structure and function to a point where there would be serious or irreversible harm.” During the first surveillance audit (Akroyd and Pierre, J. 2013), the status of the condition was revisited in light of an evolving spatial unit definition under the MSC's standards for evaluating habitat structure and function, which resulted in an elevation of scale. When the scoring criteria was re-examined at the aggregated scale, it was determined reasonable to conclude that the fishery is highly unlikely to reduce habitat structure and function to a point where there would be serious or irreversible harm, and the condition was closed. Rational for this conclusion was based on the extent of habitats remaining outside the areas in which hoki is bottom trawled, the trend of a shrinking bottom trawl footprint in the most heavily trawled habitat types, and the ecosystem function indicated by trawl surveys in the Chatham Rise. However, it was noted that the justifications were highly inferential and the conclusion was not made with a high degree of confidence. A recommendation was raised to further monitor and assess the bottom trawl footprint by BOMEC habitat class (or an improved tool, when one becomes available). The recommendation has been repeated through subsequent surveillance audits and remains current as of the 4th surveillance audit (Akroyd et al. 2016). Throughout the present certification cycle, the DWG Ltd. has expressed concern regarding the applicability of the BOMEC classification scheme. It is now understood by the surveillance team (Akroyd et al. 2016) that DWG Ltd. considers the BOMEC habitat classification scheme to be of limited value for assessing trawl and dredge impacts on benthic fauna and habitats in New Zealand waters; and development of a spatially explicit, risk-based methodology has been identified as the preferred approach going forward. Meanwhile, progress has been noted with respect to quantification of the trawling footprint, knowledge of benthic distributions, and assessment of risks of trawling impacts on benthic habitat. The current Public Comment Draft Report for the new MSC reassessment for New Zealand hoki, hake and ling trawl fisheries do not attribute any condition or recommendations (O’Boyle et al. 2018).
Last updated on 14 August 2018
Given their large biomass, hoki are a key component of the upper slope (200-800 m), and the importance of understanding of prey-predator relationships between hoki and other species is noted, particularly since substantial changes in the biomass of hoki have taken place since the fishery began (Fisheries New Zealand 2018). A past study (Anderson and Smith 2005 in (Ministry for Primary Industries 2016a) estimated annual hoki discards in the hoki fishery to be between 600-2,100 tonnes; an amount that is considered large enough to have potential impacts on the diets of scavenging species (Forman and Dunn 2012 in Ministry for Primary Industries 2016a). Hoki are prey to several piscivores, particularly hake but also stargazers, smooth skates, several deep water shark species, and ling; (Dunn et al 2009a in Fisheries New Zealand 2018). The proportion of hoki in the diet of hake averages 38% by weight, and has declined since 1992 (Dunn & Horn 2010 in Fisheries New Zealand 2018), possibly because of a decline in the relative abundance of hoki on the Chatham Rise between 1991 and 2007. Information on the size and recruitment stage of hoki eaten by predators is lacking, and could be an important factor with regard to fishery interaction and potential for competition (Ministry for Primary Industries 2017). Tuck et al. (2009) focused study on the ecosystem processes in Chatham Rise and Sub- Antarctic area showed some evidence of a change in ecosystem indicators over time. They reported an increasing of evenness or reduction in diversity. However, there was no evidence that species were being lost from the food-web (O’Boyle et al. 2018).