Blue Grenadier

• Commonwealth Southern and Eastern Scalefish and Shark Fishery (Commonwealth Trawl Sector) (10,958t in 2021/22)

Blue Grenadier (also known as Hoki) are a bentho-pelagic predatory finfish found throughout Australian, New Zealand and wider southwestern Pacific Ocean waters. They usually live on or near the bottom in depths from 400-1000m, but may occasionally move up into mid-waters. Large adult fish generally occur deeper than 400 m, while juveniles may be found in shallower water, more commonly found in large estuaries and bays, and may even enter freshwaters.

Blue Grenadier are caught using bottom and midwater trawl in Australia in the Commonwealth-managed Southern and Eastern Scalefish and Shark Fishery (SESSF), which is Australia’s largest source of locally caught finfish for the domestic market.

The fishery has made significant progress in reducing protected seabird bycatch, though fur seal bycatch is potentially increasing. Seal Excluder Devices (SEDs), which act as escape hatches for seals that enter trawl nets, are mandatory. All trawl boats must have a seabird management plan in place to guide how each boat aims to reduce interactions with seabirds while actively fishing. Many of the solutions to seabird interactions have been fishing industry-led innovations and are proving highly successful in reducing these impacts.

Most concerning is bycatch of fishes – including eastern gemfish and school shark – which used to be primary or secondary target species of the fishery, that have been so severely overfished by the SESSF that they are now on the Australian Threatened, Endangered or Protected Species lists.

No Australian fishery has pushed more of its former target and secondary species onto our endangered species lists, and there is no evidence of recovery for most of these species. Special rebuilding strategies that allow these species to be caught and sold while holding this protected status are largely failing to deliver sufficient if any actual rebuilding.The SESSF blue grenadier fishery has an adequate level of independent observer coverage to support collection of reliable information on bycatch species, which is welcome.

The SESSF operates around a global ocean heating hotspot, warming at almost four times the global average. While serious climate impacts have been attributed to declining SESSF fish stocks for around a decade, there is still no explicit consideration of climate impacts when setting future catch limits. Significant research is underway in this area, which is welcome but overdue.

There has been considerable investment in scientific research around the ecosystem and habitat impacts of the fishery, but this has not been supported by sufficient implementation of meaningful protections from fishing and climate-related impacts in the fishery, which have both been severe. Commonwealth waters marine parks are in place throughout the fishery but were designed primarily to avoid key fishing grounds, so confer little benefit. While marine parks should be a valuable and cost-effective tool for protecting vulnerable species and habitats; providing both resilience and a scientific resource to manage climate impacts; they (along with existing fishery area closures), protect almost none of the most heavily fished habitats in the fishery. Improving marine park protection will be critical to addressing and rebuilding the future sustainability of the SESSF fishery.

• New Zealand Hoki Fishery (136,719t caught in 2015-16; 9,994t imported into Australia in 2016)

Blue grenadier is managed as two separate stocks in New Zealand fisheries. The Hoki fishery has recovered from historic overfishing, and stocks have been stable above sustainable levels for several years.

There are significant concerns over threatened species bycatch and habitat damage in this fishery. The New Zealand blue grenadier fishery catches a number of endangered seabird species, including white-capped, Buller’s and Salvin’s albatross, petrels and shearwaters. Risk assessments have identified that Salvin’s albatross is at risk of further population decline and white-capped albatross are in decline as a result of fishing activities.Seabird bycatch has not declined over the last decade, with recorded seabird captures in 2014-15 the highest in that period. Use of mitigation devices that reduce seabird interactions are in place; bycatch of seabirds has declined from 2015, but continues to be unacceptably high and likely resulting in the ongoing decline of threatened and protected seabirds.

In addition to seabirds, the fishery also captures seven species of deepwater sharks (known as dogfish). The biology of these species are poorly known, but are potentially vulnerable to overfishing due to their slow growth rates and low reproductive output.

Blue grenadier is trawled both on and above the seafloor over a large area of NZ’s oceans. Seabed mapping of the trawled area is limited, but sensitive seafloor-dwelling species (corals and sea fans) have been identified in both mapped areas and in trawl nets, which means that fishing activity is directly threatening these long-lived and sensitive species. There are few areas protected within hoki trawl depths, although Marine Protected Area Network planning is underway in NZ, which should protect sensitive marine habitat.