Hoki grow quickly reaching 27 to 35 cm total length (TL) during the first year and growth rates appear to be increasing since 1983 (Mfish 2009). There are two populations of Hoki in New Zealand, with fish in the eastern population having a slightly slower growth rate (K=0.161-0.232) than fish in the western population (K=0.213-0.261) (Francis 2003; Mfish 2009). Overall, Hoki have a medium growth rate. Males reach sexual maturity at 60-65 cm TL and females reach maturity at 65-70 cm TL (Mfish 2009). These sizes correspond to an age range of 3-5 years (Mfish 2009). Females reach a larger maximum size of 130 cm TL and 7 kg, compared to the maximum size of 115 cm TL reached by male Hoki (Mfish 2009). The maximum age of Hoki is 20- 25 years (Fishbase 2010; Mfish 2009). There is no available estimate for intrinsic rate of increase.

Hoki aggregate and spawn off the west coast of the South Island of New Zealand from mid July to late August (Mfish 2009). Spawning aggregations begin around Hokitika Canyon (depths of 300-700 m) in late June and spread north to an area off Westport towards the end of the spawning season (Mfish 2009). A separate spawning aggregation occurs in Cook Strait (between the North and South Island) from June to mid September (Mfish 2009). Additional “satellite” spawning areas occur off the east and south-west coasts of the South Island (Anonymous 2010). Fishermen target Hoki during these spawning aggregations (Mfish 2009). Hoki form single species mid-water spawning aggregations (O’Driscoll 2004), although species such as ling and spiny dogfish are often present and caught as bycatch (MFish 2010). The existence of multiple spawning sites may make Hoki less susceptible to overexploitation on spawning grounds. We have decided to subtract points until further information on this effect is found.

Hoki are found around New Zealand and southern Australia (Fishbase 2010). In New Zealand they are distributed from 34° S to 54° S and from 10 m to 1500 m depth (Mfish 2009). Juvenile Hoki are commonly found in shallow water while adults are usually found at depths greater than 400 m (Mfish 2009). There are two separate populations of Hoki in New Zealand, western and eastern, that spawn separately in the waters of the west coast of the South Island and in Cook Strait respectively (Mfish 2009). Migrations by adults to spawning grounds occurs in the winter and during the remainder of the year adult Hoki are found around the edge of the Stewart and Snares shelf, large areas of the sub-Antarctic and Chatham Rise and around the North Island, although not in large numbers (Mfish 2009). Chatham Rise has a population of juveniles year round (Mfish 2009). Because Hoki are found in both New Zealand and Australia and thus have a medium range, no points were subtracted.

There is conflicting evidence that declines in Hoki abundance over the years has been due to environmental and oceanographic conditions. It has generally been thought that El Nino/Southern Oscillation (ENSO) conditions tend to be good for Hoki survival, and long-term weather patterns such as the 20-30 year Interdecadal Pacific Oscillation may be affecting recruitment, as well as the sea warming that has been occurring in the Tasman Sea (Bull and Livingston 2001). Bull and Livingston used models to predict strong year classes for the western population were associated with cooler sea surface temperatures, a negative Southern Oscillation Index and southwesterly or westerly flow along the west coast of the South Island. The work by these authors also suggested there was a negative relationship between conditions with the NW flow in autumn and the year class size of the eastern population of Hoki. However, the conclusions from Francis et al. (2006) do not support the initial results provided by Bull and Livingston (2001). Therefore, the New Zealand Ministry of Fisheries still considers information on the influence of climate changes on recruitment levels to be needed (Mfish 2009). Despite the conflicting reports we have subtracted points because broad-scale environmental changes likely have an effect on Hoki populations, even if the impact is not fully understood.

Hoki have high fecundity, spawning from late June to the middle of September (Mfish 2009). They produce 1-2 million eggs per year, but not all adult Hoki breed in a given year (Schofield and Livingston 1998; MFish 2009). Studies in the Sub-Antarctic indicate that between 40-67% of Hoki age 7 and older spawn in a given year (Livingston et al. 1997; Livingston and Bull 2000).

In 2009 the biomass of the eastern population of Hoki was 204-213% of that needed to produce the maximum sustainable yield (MSY) and the biomass of the western population was 144-156% of MSY (MFish 2009). This equates to approximately 48% and 38% of the virgin biomass for the eastern and western populations, respectively (MFish 2009). The 2010 population assessment predicts the eastern and western populations are between 40-52% and 51-57% of virgin biomass respectively (MFish 2010). Both populations are within the target reference point of 35-50% of virgin biomass and are well above the levels needed to produce MSY (MFish 2009; 2010).

In the non-spawning fishing grounds there are more females than males, while on the spawning grounds the ratio was generally equal. Sex rations, particularly on the west coast of South Island (WCSI), have been variable over the years. From 1999/2000 to 2003/04 the sex ratio was highly skewed with more females than males being caught. This ratio has since reversed in the last four years as the catch of younger fish has increased (MFish 2004; Livingston and Bull 2001). The proportion of fish less than 65 cm in the catch during the 2009/10 season was 45% and the proportion of small fish in all fisheries has been increasing since 2002 (MFish 2009). For example, in Chatham Rise, WCSI, Cook Straight and the Sub-Antarctic, 57%, 31%, 27% and 25% respectively, of Hoki are less than 65 cm (MFish 2009). During 2009 in the Sub-Antarctic fishery, Hoki larger than 80 cm made up 49% of the catch, while those less than 65 cm made up only 14% of the catch (Mfish 2009). There has been an increase in the amount of larger Hoki in the catch since the 2005-2006 season (Mfish 2009). This information should be used with caution since it is based on commercial catch and fishermen tend to target larger fish, which are generally female (MFish 2010). It is thought the increase in females with increasing age could be caused by an increase in the natural mortality in older males (MFish 2010). In addition, the behavior of males during spawning could skew the sex distribution of the catch (MFish 2010). We have therefore elected to neither subtract nor add points.

Hoki eat mid-water fishes (e.g. Lantern fish) and shrimps (Clark 1985a,b; Dun et al. 2007). Stargazers, smooth skates, deep water sharks, ling and hake prey on Hoki (Clark 1985a,b; Dun et al. 2007). A 4-fold decline in relative abundance of Hoki on the Chatham Rise from 1991 to 2001 could have caused some effects to the trophic dynamics in that area (Bull et al. 2001). Abundance in all areas, however, has now increased to healthy levels and is likely sufficient for predators.

Hoki are taken by both mid-water and bottom trawls (MSC 2004; NZ Hoki 2004), with mid-water trawls used in spawning fisheries and bottom trawls used in non-spawning fisheries (MFish 2009). Around 55% of the Hoki catch is taken in the non-spawning fisheries and 45% in the spawning fisheries (Dunn and Livingston 2004). Mid-water trawls fish on or near the seabed and are mostly used in the western population, while bottom trawls are used on the Chatham Rise (MFish 2009). Bottom trawling for Hoki could result in benthic disturbances that could change the benthic habitat (MFish 2008). Considering that mid-water trawls typically cause little habitat damage (core point = 3), while bottom trawls can cause substantial habitat damage (core point = 1), a middle score of 2 was chosen.

Bottom trawls used to capture Hoki may cause damage to the seafloor, affecting the habitat of other species. However, Hoki are a semi-pelagic species, and the open-water habitat remains robust and viable.

Hoki Management Areas (HMA) in place for 2009-2010 include: Cook Strait, Canterbury Banks, Memoo and Puysegur (DWG 2009). Trawlers larger than 28 m are not allowed to target Hoki within these HMA’s (DWG 2009).

In the Chatham Rise and the Sub-Antarctic, where most of the bottom trawling occurs, the seabed is gravel, mud, or flat clay-like strata, which are relatively resilient (MFish 2004).

Hoki are managed as two separate populations, western and eastern, in New Zealand (Mfish 2009). The New Zealand Ministry of Fisheries (MFish) is responsible for conservation and management of fisheries, which sets catch limits for recreational fisheries, indigenous subsistence fishing, and the Total Allowable Commercial Catch (TACC) for commercial fisheries. Total Allowable Commercial Catch (TACC) limits are the major measure in place to manage the Hoki fishery, and are determined based on data from recent population assessments. A voluntary catch split arrangement has set the TACC for 2009/10 at 110,000 t, with the western catch limit being 50,000 t and the eastern limit being 65,000 t (Mfish 2009). Some of the management responsibilities for Hoki come from within the industry. The Deepwater Group (DWG) represents 95% of all deepwater and middle-depth quota holders (MSC 2010). The DWG’s Hoki Operational Procedures (HOP) is used by the DWG to manage and monitor fishing effort and Hoki catch size within agreed Hoki Management Areas (HMAs). High proportions of juvenile Hoki are found within these HMAs and vessels larger than 28 m are not permitted from targeting Hoki in these areas (DWG 2009). MFish also monitors activity and Hoki bycatch in these areas by requiring vessels to notify the DWG of their intention to target alternative species in the HMAs (DWG 2009). If these vessels have an observer on board, the observer will do length-frequency sampling of Hoki and if not observer is present the vessel must provide the DWG with copies of all catch records from within the HMA (DWG 2009). To aid enforcement, vessels longer that 28 m are required to operate a satellite communication link to the Ministry of Fisheries and the New Zealand Defense Forces occasionally sweep the Economic Exclusive Zone (EEZ) to make sure regulations are being followed (MSC 2010). Additionally, MFish and the DWG recommends that vessels move away from areas where juvenile (<55 cm) Hoki make up more than 20% of the Hoki catch by number (MSC 2010).

The Hoki fishery has been certified by the Marine Stewardship Council (MSC) in 2001 and was recertified in 2007 (MSC 2007). These certifications indicate that management and other issues have been thoroughly assessed, and that the fishery is sustainable. Since the original MSC assessment in 2001, several management changes were made that improved the sustainability of the Hoki fishery according to the MSC (MSC 2007). These changes included: partnership between the Ministry of Fisheries and quota owners, additional research and updated stock assessments, reduction of the TACC, rebuilding strategy implemented for western population, development of a Fisheries Plan, improved compliance, reduced interactions with seabirds and marine mammals and the introduction of benthic protected areas (MSC 2007).

Population assessments are conducted annually, and catches are monitored. Assessments utilize trawl surveys, acoustic surveys and catch-at-age and catch per unit effort data (CPUE) from commercial fisheries, and use sophisticated modeling programs (MFish 2004).

A recovery plan was used previously when Hoki populations were considered overfished. The results of the latest population assessment indicate both populations are healthy and therefore no recovery plan is needed (MFish 2009).

This fishery is not subsidized and is not considered overcapitalized.

Over 470 species or species groups of bycatch have been identified by fishery observers in the Hoki fishery (MFish 2009). However, most of these were caught in low numbers and represented non-commerical fish and invertebrate species including: javelinfish, ratttails, dogfish, deepwater sharks, and unidentified sharks and skates (MFish 2009). Bycatch levels in the Hoki, hake and ling fisheries from 2000-2007 ranged from 36,000 to 58,000 t per year (MFish 2009). The highest bycatch levels were seen from 1999 to 2004 (MFish 2009). Basking sharks are caught as bycatch in the Hoki fishery and are listed on Appendix 2 of CITES, Appendix 1 of the Convention on Migratory Species and are on the Department of Conservation’s threat classification list (MFish 2009). The Ministry of Fisheries is currently consulting on possible management options that would provide full protection for basking sharks in New Zealand waters, and from New Zealand flagged vessels operating on the high seas (MFish 2010). The proposed regulatory amendments would come into effect in December 2010 (MFish 2010). Hake, ling and southern blue whiting are all taken as bycatch in Hoki fisheries. However, the catch of these species counts toward the TACC set for these species by the New Zealand Minister of Fisheries (NZ Hoki 2004).

In the fishing years 1997-98, 1998-99, 1999-2000, Hoki trawl fisheries took an average of 98 seabirds per year with over 80% of them dead (Baird and Thompson 2002). However, the bird species taken are not considered to be endangered or threatened (MSC 2001). Catch estimates for seabirds in this fishery are difficult to make due to their low representation in the catch and identification problems (Mfish 2009). The majority of seabirds are caught in the Chatham Rise and Cook Strait fisheries (Mfish 2008). Fur seals and sea lions may also be taken in the trawl fisheries. The observed number of interactions between fur seals and vessels targeting Hoki, ranged from 29 to 120 between 2002 and 2008 and the estimated number of interactions (based on these captures) ranged from 216 to 1,032 (Abraham et al. 2009). The percentage of fur seals that are released alive is 6.7% for the west coast of the South Island, 28% for the Chatham Rise and 18.7% for the Cook Strait (Abraham et al. 2009). The Marine Stewardship Council reports that seabird interactions in the Hoki fishery have declined from 8.73 captures/100 observed tows in 2000-2001 to 1.31 captures/100 tows in 2006-2007 (MSC 2007). The MSC (2007) also reports New Zealand fur seal captures have declined from a high of 5.72/100 observed tows in 2004-2005 to 1.65 captures/100 tows in 2006-2007.

The New Zealand Hoki Fishery Management Company (HFMC) requires training for crews to learn techniques to decrease seabird bycatch, and encourages the use of the Brady Bird Baffler. This device consists of arms and streamers, which hang off the side of the vessel, and increase the birds' perception of vessel size, keeping them out of harms way (NZ Hoki 2004). The New Zealand Hoki Fishery Management Company has in place a Code of Practice to reduce bycatch of fur seals and sea lions. The code includes a detailed set of measures that can be used to avoid catches of these species during gear setting and hauling, and a requirement for an observer on each vessel to determine if a mammal has been taken. They also must organize timely humane assistance for the animal if one is caught. There has been an apparent decreasing trend in the amount of fur seals taken in Hoki trawl fisheries. In the west coast of the South Island, bycatch has decreased from 561 in the 1999-2000 fishing year to 146 in 2002-2003. The rate of seal bycatch per trawl has similarly decreased (MSC 2004).

Vessels over 28 m have individual vessel management plans (VMPs) that have management efforts aimed at reducing the risk of injury or death to foraging seabirds (since 2006) (MSC 2007). Voluntary management efforts in place for the entire Hoki fleet include the adherence to offal management practices (Mfish 2008). Hoki vessels larger than 28 m are required to use bird mitigation devices (Mfish 2008). Additionally, these vessels must comply with Marine Mammal Operational Procedures, which have been put into place to reduce interactions with marine mammals (MSC 2007).

There are minimum mesh sizes in place to reduce the catch of juvenile Hoki (NZ Hoki 2004). Small Hoki are protected through the closure of the Mernoo Bank and Canterbury Banks year-round to trawlers targeting Hoki (http://www.fish.govt.nz/en-nz/Recreational/default.htm).

Hake, Ling and warehou fisheries overlap with Hoki fisheries, and take Hoki as bycatch. However, this catch counts toward the total Hoki quotas (Livingston et al. 2003).