Grey Mackerel – Northern Territory Offshore Net and Line Fishery

Assessment Summary

Grey Mackerel

 

Unit of Assessment

Product Name: Grey Mackerel

Species:  Scomberomorus semifasciatus

Stock: Grey Mackerel – North West Northern Territory and Grey Mackerel – Gulf of Carpentaria

Gear type: Pelagic Gillnet

Fishery: NT Offshore Net and Line Fishery

Year of Assessment: 2017

Fishery Overview

The following summary is adapted from NTG (2017):

The NT Offshore Net and Line Fishery (ONLF) extends seaward from the high water mark to the outer limit of the AFZ and targets Australian Blacktip Sharks (Carcharhinus tilstoni), Common Blacktip Sharks (C. limbatus) and Grey Mackerel (Scomberomorus semifasciatus) using a variety of gear.

Demersal longlines can be used throughout the fishery whereas pelagic gillnets and pelagic longlines can only be used beyond 2 nm and 3 nm off the coast, respectively. Pelagic gillnets are the primary gear used by this fishery and are generally set within 15 nm of the coast, in the Gulf of Carpentaria. Longlines have not been used in the fishery since 2013, primarily as a result of the drop in shark fin price. Licensees can use nets up to 2000 m in length, but most choose to use nets in the order of 1000 m to 1500 m. The drop of the net must not exceed 100 meshes and the size of each mesh panel typically ranges from 160 mm to 185 mm when stretched. Pelagic gillnets are weighted and have a buoyed headline. Pelagic longlines must not exceed 15 nm in length and cannot have more than 1000 snoods (hooks) attached. Automated baiting gear is prohibited.

Two of the target species in this fishery, the Australian Blacktip Shark and the Common Blacktip Shark, are very difficult to separate by eye and have traditionally been reported as “Blacktip Shark”. Although the shark identification skills of many licensees are improving, some grouping still occurs in logbook returns. The grouping convention is also used here so as not to misrepresent the harvest of either species.

Currently the longline licences are not operating due to poor market prices for large shark product. Consequently, Grey Mackerel has become the most targeted species and has been the highest proportion of the catch for the last 5 years.

A total of 522 t of fishes were harvested by Offshore Net and Line Fishery licensees in 2015. Grey Mackerel formed the bulk of the harvest (78 per cent) followed by the Blacktip Shark group (7 per cent) and Spot-Tail Sharks (2 per cent). The primary byproduct species were Spanish Mackerel (5 per cent), Longtail Tuna (1 per cent) and Hammerhead Sharks (Sphyrna spp.) (1 per cent).

Management responsibility for the ONLF rests with the Northern Territory Fisheries Joint Authority (NTFJA), comprising the Australian Government Minister for Agriculture and the Northern Territory Minister for Primary Industry and Fisheries. Under an Offshore Constitutional Settlement arrangement between the Australian Government and the Northern Territory Government, the fishery is managed under the Northern Territory legislation. Day to day management is carried out by the Northern Territory Department of Primary Industry and Fisheries.

Figure 1 Catch trends

Risk Scores

Performance Indicator

Western NT

Gulf Of Carpentaria

C1 TARGET SPECIES

LOW

LOW

1A: Stock Status

LOW

LOW

1B: Harvest Strategy

MEDIUM

MEDIUM

1C: Information and Assessment

LOW

LOW

C2 ENVIRONMENTAL IMPACT OF FISHING

LOW

LOW

2A: Non-target Species

LOW

LOW

2B: ETP Species

MEDIUM

MEDIUM

2C: Habitats

LOW

LOW

2D: Ecosystems

LOW

LOW

C3 MANAGEMENT

LOW

LOW

3A: Governance and Policy

LOW

LOW

3B: Fishery-specific Management System

LOW

LOW

Summary of main issues

  • The two stocks of Grey Mackerel and the north are estimated to be above levels consistent with MSY, although there are no well-defined harvest control rules for any stock that would serve to reduce exploitation as the point of recruitment impairment is approached.
  • There are substantial uncertainties about the status of the Blacktip Shark complex in the Gulf of Carpentaria, largely driven by uncertainties in reporting.
  • The ONLF is relatively well-placed against most Component 2 performance indicators, although the low level of observer coverage may not be sufficient to accurately quantify the level of ETP species interactions.
  • Illegal fishing for shark fins by small scale Indonesian vessels was a serious concern in the mid-2000s, but is considered to have since declined.

Outlook

Western NT

Component Outlook Comments
Target species Improving ↑ Management arrangements in the ONLF are currently under review with a new management plan scheduled to be released shortly.  This is expected to include well-defined harvest control rules consistent with the NT Fisheries Harvest Strategy Policy.
Environmental impact of fishing Stable = No major changes to Component 2 scoring are expected.
Management system Improving ↑ Management arrangements in the ONLF are currently under review with a new management plan scheduled to be released shortly.  This is expected to include fishery specific objectives and a harvest strategy consistent with the NT Fisheries Harvest Strategy Policy.

Gulf of Carpentaria

Component Outlook Comments
Target soecies Improving ↑ Management arrangements in the ONLF are currently under review with a new management plan scheduled to be released shortly.  This is expected to include well-defined harvest control rules consistent with the NT Fisheries Harvest Strategy Policy. In the Queensland, GOCIFFF harvest strategies with well-defined harvest control rules will be developed by 2018 as part of the Queensland Government’s Queensland Sustainable Fisheries Strategy 2017-2027.
Environmental impact of fishing Stable = No major changes to Component 2 scoring are expected.
Management system Improving ↑ Management arrangements in the ONLF are currently under review with a new management plan scheduled to be released shortly.  This is expected to include fishery specific objectives and a harvest strategy consistent with the NT Fisheries Harvest Strategy Policy.

Assessment Results

COMPONENT 1: Target species

1A: Stock Status

CRITERIA: (i)The stock is at a level which maintains high productivity and has a low probability of recruitment overfishing

(a) Stock Status – Grey Mackerel – Western NT Stock

LOW RISK

At least five Grey Mackerel biological stocks exist across northern Australia, including a Western Australia stock, a north-west Northern Territory (Timor/Arafura) stock, a Gulf of Carpentaria stock, a north-east Queensland stock and a central east Queensland stock (Welch et al. 2009). The ONLF harvests both the north-west Northern Territory stock (NWNT) and the Gulf of Carpentaria (GoC) stock. Model outputs from data up to 2011 indicate that Western NT stock of Grey Mackerel has recovered from overfishing by Taiwanese fishers in the 1970s and 1980s, with biomass currently at 81% of the unfished level and current effort levels at only 12% of those at BMSY (Grubert et al. 2013). It is highly likely the stock is above the point of recruitment impairment (PRI) and above levels consistent with MSY.

(a) Stock Status – Grey Mackerel – GoC stock

LOW RISK

The model for the GoC stock, which was never subject to overfishing by Taiwanese fishers, includes data from both ONLF and the Queensland Gulf of Carpentaria Inshore Finfish Fishery (GOCIFFF) and indicates that, despite recent increasing catches, the current biomass is 74% of unfished levels (Grubert et al. 2013). This evidence suggests that it is highly likely the stock is above the PRI and likely to be above levels capable of producing MSY.

PI SCORE – LOW RISK – NWNT stock; GoC stock

1B: Harvest Strategy

CRITERIA:  (i)There is a robust and precautionary harvest strategy in place.

(a) Harvest Strategy

The main management measures in place for the gillnet sector of ONLF include:

  • Limited entry – 17 licensees in 2017;
  • Spatial restrictions – pelagic gillnetting is permitted seaward of two nautical miles offshore only;
  • Gear restrictions – maximum net length (2,000 metres) per licence with a maximum of 100 meshes drop, prohibition of bottom setting of nets, net mesh size restrictions (between 160 and 185 millimetres)
  • Effort limits – total allowable effort limits allocated through individually transferable effort units, including 1,599 net fishing days per annum.

The fishery is monitored through compulsory catch and effort logbooks requiring fishers to submit monthly summary returns. Catch and effort is validated through independent observer coverage (NTG, 2017).  The fishery also has a performance management system with catch trigger points for target species (e.g. a 30% change in catch for two calendar years). If any of these triggers or limits are breached an appropriate management response is enacted within 12 months to restrict harvest.

Periodic stock assessments are also undertaken of the main target species including both Grey Mackerel and Blacktip Sharks (e.g. Grubert et al, 2013).  Consultation on management arrangements is primarily undertaken through the Offshore Net and Line Advisory Group (ONLAG), including members from industry, recreational and Fishing Tour Operators (FTO) representatives, compliance and departmental officers.

DPIF (2016) report that the Department is “currently undertaking a review of the Offshore Net and Line Fishery (ONLF).  The output of this review will be management framework whose objective will be to implement a management system that utilises total allowable commercial catch (TACC) and individual transferable quotas (ITQ’s) to sustainably and profitably manage the ONLF in accord with the objectives of the Fisheries Act 1988.  A harvest strategy is being developed which includes management objectives, performance measures and trigger reference points using a risk management approach, and will be formally contained in the management framework.  Performance measures will prescribe specific actions that will take place if a trigger point is breached.”  We also note that the Northern Territory Government has recently released a Northern Territory Fisheries Harvest Strategy Policy (DPIR, 2016) which requires that harvest strategies with well-defined HCRs be implemented in all key NT fisheries when their respective fishery regulations or management plan is next reviewed.

Grey Mackerel – Western NT stock

 LOW RISK

The ONLF is the only commercial fishery accessing the western NT stock of Grey Mackerel. In addition to the measures outlined for the ONLF above, there is a Personal Possession Limit (PPL) of five Grey Mackerel for recreational anglers, although recreational catches are thought to be small (West et al, 2012).

Given the healthy state of the Western NT stock, there has been little need in recent times to reduce exploitation.  Nevertheless, the management strategy has mechanisms to allow for responses to declining stock status and all of the elements appear to work together to achieve the stock management objectives in criterion 1A(i).  Accordingly, we have scored this SI low risk.

Grey Mackerel – GoC stock

LOW RISK

In the GoC Grey Mackerel stock, harvests are shared with the Queensland Gulf of Carpentaria Inshore Finfish Fishery (GOCIFFF) which took the majority (88 per cent) of the commercial harvest in 2015 and has averaged 80–90 per cent of the harvest in recent years (Helmke et al, 2016).

In the GOCIFFF harvest limitation for the target species is achieved primarily through limiting licences in the commercial sector, restricting gear, a minimum legal size limit of 60 cm, a recreational personal possession limit of five fish and spatial closures.

Helmke et al (2016) noted “There has been a rising trend in commercial catch rate since targeted fishing for Grey Mackerel began in the Gulf of Carpentaria in the late-1990s. Queensland catches and catch rates reached record levels in 2010 and 2012, respectively. Although the Queensland catch rate dropped in 2013 (60 kg per 100 m net), it has steadily risen in 2014 (68 kg per 100 m net) and again in 2015 (86 kg per 100 m net). The most recent assessment estimates that the biomass in 2011 was 74 per cent of the unfished biomass. The stock is not considered recruitment overfished. Stock reduction analysis of Grey Mackerel in the Gulf of Carpentaria, using Queensland and Northern Territory catches also concluded that the harvest rate is at 26 per cent of that required to achieve MSY”.

Queensland introduced changes to the net fishery at the beginning of the 2012 season to reduce pressure on Grey Mackerel. The measures decreased the total length of available net for the Queensland component of the stock by two-thirds, from 27 km to 9 km, in the offshore component of the fishery. Changes to the Queensland inshore fishery (within 7 nautical mile of the coast) also reduced the capacity for boats to target Grey Mackerel.  A Performance Management System (PMS) was previously in place for the fishery that aimed to monitor trends against reference points (e.g. catch and/or catch rates being 30% above or below the annual average of the previous five years), although this appears to have been largely discontinued. Stock status is assessed annually using a weight of evidence approach, and periodically through quantitative assessments (e.g. Grubert et al, 2013).

In the GOCIFFF, there is some evidence that the harvest strategy is responsive to the state of the stock given the measures to reduce perceived pressure on Grey Mackerel introduced in 2012.  Status is assessed regularly, although no formal harvest control rules are in place.  In the ONLF, there has been no reason to reduce exploitation as a result of stock declines, although stock status is assessed at least biennially based on relevant indicators and tools existing to reduce exploitation if necessary.  Recent estimates suggest the stock is being harvested at levels well below MSY, with SRA analysis concluding that the harvest rate is at 26 per cent of that required to achieve MSY (Grubert et al, 2013).  Accordingly, we have scored this SI low risk.

Nevertheless, the fishery would be better placed against this SI with well-defined harvest control rules in place which served to reduce exploitation as PRI is approached.

The Queensland Government has recently announced the Queensland Sustainable Fisheries Strategy 2017-2027 which commits amongst other things to improved monitoring and research and the adoption of harvest strategies for all major fisheries by the end of 2020, with a priority to develop trawl, crab and inshore fisheries strategies by the end of 2018 (DAF, 2017a).  Harvest strategies will include well-defined harvest control rules and aim to maintain stocks at levels above MSY.

(b) Shark-finning

NA

CRITERIA: (ii) There are well defined and effective harvest control rules (HCRs) and tools in place.

(a) HCR Design and application

Grey Mackerel – Western NT stock

MEDIUM RISK

While harvest strategy performance is assessed against a set of trigger points, these currently do not link clearly to the state of stock nor set out pre-agreed response to reduce exploitation if the PRI is approached. Accordingly, “well-defined” HCRs are not in place and the fishery is more consistent with a medium risk for this SI, with the strategy providing generally understood harvest controls that are expected to reduce the exploitation rate as the PRI is approached. Nevertheless, we note that management arrangements in the ONLF are currently under review and future arrangements are expected to include well-defined HCRs consistent with the NT Fisheries Harvest Strategy Policy (DPIR, 2016).

Grey Mackerel – GoC stock

MEDIUM RISK

In the ONLF, while harvest strategy performance is assessed against a set of trigger points they currently do not link clearly to the state of stock nor set out pre-agreed response to reduce exploitation if PRI is approached.  In the GOCIFFF, monitoring was previously undertaken against trigger points in a specific PMS for the fishery, although assessments against framework have been largely discontinued. Accordingly, “well-defined” HCRs are not in place in either jurisdiction.

Nevertheless, assessments of stock status are undertaken annually in the Northern Territory (e.g. NTG, 2017), as well as by both jurisdictions biennially through the Status of Key Australian Fish Stocks process (e.g. Helmke et al, 2016), and tools are in place (e.g. adjustments to net length, effort limits) that allow exploitation to be reduced if the stock was identified as approaching the PRI. Moreover, the 2012 changes to reduce the potential for exploitation of Grey Mackerel in Queensland in response to concerns about stock status provide some evidence that the management system will act in response to concerning trends.  To that end, generally understood harvest control rules and tools could be said to be available which are expected reduce exploitation as PRI is approached.

We note that management arrangements in the ONLF are currently under review and future arrangements are expected to well-defined HCRs consistent with the NT Fisheries Harvest Strategy Policy (DPIR, 2016).  We also note that a harvest strategy with well-defined harvest control rules aiming to maintain stocks at levels above MSY will be developed for Queensland’s inshore fisheries by the end of 2018 as part of the recently announced the Queensland Sustainable Fisheries Strategy 2017-2027 (DAF, 2017a).

PI SCORE – MEDIUM RISK – NWNT stock, GoC stock

1C: Information and Assessment

CRITERIA: (i) Relevant information is collected to support the harvest strategy.

(a) Range of information – Western NT stock; GoC Stock

LOW RISK

The biology of Grey Mackerel is well known including information on stock structure, reproductive biology, age, growth and longevity (e.g. Helmke et al, 2016 and references therein). Good information on commercial sector fleet composition, catch and effort is available through licensing details for both the ONLF and GOCIFFF and compulsory logbooks.  Independent information is also available through observer coverage in the ONLF.  Fishing Tour Operators (FTO) in the NT also report catch and effort information by species. Periodic recreational fishing surveys provide information on the fleet composition and catch and effort by this sector (e.g. West et al, 2012). Recreational catch of Grey Mackerel in the NT was estimated to be around 10t in 2013.  Recreational catch in Queensland on the GoC stock is unknown, but thought to be low.  While the Indigenous harvest is unknown it is likely to be very small given the offshore distribution of the target species (NTG, 2017).  The available information is sufficient to support the harvest strategy.

(b) Monitoring and comprehensiveness Western NT stock

LOW RISK 

Grey Mackerel catches are monitored annually through the stock status reporting process (e.g. NTG, 2017), and there is good information on catches taken in the ONLF.  Additionally, regular information on the age and size structure of the target species is gathered during observer trips in the ONLF, and recreational catch information is provided through periodic recreational surveys (e.g. West et al, 2012).  Although there are no biologically-based harvest control rules in the fishery, the ONLF Performance Management Framework contains several indicators that are monitored annually and designed to evaluate the harvest strategy and provide triggers for management action. Additionally, there are periodic assessments of each stock which provide current estimates of biomass compared to B0 (e.g. Grubert et al, 2013).

Grey Mackerel – GoC Stock

LOW RISK

Grey Mackerel catches are monitored annually through the stock status reporting process and there is good information on catch and effort from the GOCIFFF and ONLF, which account for the majority of UoA removals.   Additionally, regular information on the age and size structure of the target species is gathered during observer trips in the ONLF.  Information on recreational catch is provided through periodic surveys (e.g. West et al, 2012; Webley et al, 2015), although catch estimates from the 2013/14 Queensland survey are considered uncertain.  Periodic assessments of stock status have been undertaken which provide current estimates of biomass compared to B0 (e.g. Grubert et al, 2013). Although there are no well-defined HCRs in either jurisdiction, stock abundance and UoA removals are monitored with sufficient regularity to support an effective HCR (largely through assessments and monitoring undertaken in the Northern Territory jurisdiction), and there is sufficient information on other fishery removals from the stock.

CRITERIA: (ii) There is an adequate assessment of the stock status

Western NT stock

LOW RISK 

The Western NT stock has been assessed using Stock Reduction Analysis models (Grubert et al. 2013). The assessment also takes into account catches histories from the main fisheries (historical Taiwanese drift net catches, ONLF catches) as well as the major features of the species’ biology.  An IUU catch of 600t is assumed, although actual catches are not known.  The output from the model estimates current biomass as a proportion of B0.  The assessment is considered appropriate for the stock and could support a biologically-based harvest control rule.

 GoC Stock

LOW RISK 

The GoC stock of Grey Mackerel has been assessed using the same assessment approach as the Western NT stock (Grubert et al. 2013). The GoC stock assessment takes into account catch histories from both the ONLF and GOICIFFF.  The output from the model estimates current biomass as a proportion of B0. The assessment is considered appropriate for the stock and could support a biologically-based harvest control rule.

(b) Uncertainty and Peer review

Grey Mackerel – Western NT stock; GoC Stock;

LOW RISK

The stock assessments take into account the major sources of uncertainty, and has been peer reviewed externally (Grubert et al, 2013). The annual stock status reports produced by the NT are reviewed internally (e.g. NTG, 2017).

PI SCORE – LOW RISK – NWNT stock GoC stock

COMPONENT 2: Environmental impact of fishing

2A: Other Species

CRITERIA: (i) The UoA aims to maintain other species above the point where recruitment would be impaired (PRI) and does not hinder recovery of other species if they are below the PRI.

(a) Main other species stock status

LOW RISK

NTG (2017) reports that “a total of 522 t of fishes were harvested by Offshore Net and Line Fishery licensees in 2015. Grey Mackerel formed the bulk of the harvest (78 per cent) followed by the Blacktip Shark group (7 per cent) and Spot-Tail Sharks (2 per cent). Blacktip sharks have been assessed under Component 1 in the full assessment report The primary byproduct species were Spanish Mackerel (5 per cent), Longtail Tuna (1 per cent) and Hammerhead Sharks (Sphyrna spp.) (1 per cent). Bycatch (by weight) was less than 1 per cent of the harvest during 2015. Non-retained species included the Tawny Shark (Nebrius ferrugineus), rays (Family Dasyatidae), Trevallies (Carangidae spp.) and Queenfishes (Scomberoides spp.)”.  Based on this we have assessed Spanish Mackerel and Spot-Tail sharks (C. sorrah) as main other species.

Spanish Mackerel (Low risk)

Genetic evidence indicates that there are three biological stocks of Spanish Mackerel across northern Australia; however, evidence from otolith microchemistry, parasite analysis and limited adult movement (at scales greater than 100 km) indicates that there are likely to be a number of smaller biological stocks with limited interaction (Buckworth et al. 2007). Although each jurisdiction is likely to have multiple biological stocks within its boundaries, the difficulty in obtaining relevant biological and catch-and-effort information to assess each stock individually has meant that Spanish Mackerel has generally been assessed as two biological stocks (Torres Strait and east coast [Queensland]), two management units (Gulf of Carpentaria [Queensland] and Mackerel Managed Fishery [Western Australia]) and one jurisdiction (Northern Territory; Langstreth et al. 2016). The assessments that are not undertaken at the biological stock level are based on the populations that receive the highest harvest rates so that their status can be assumed to be representative of the highest level of exploitation that occurs on any population within each management unit or jurisdiction.

This assessment assesses the NT fishery at the jurisdictional level. Spanish Mackerel stocks have been assessed at a territory-wide level, including information up to 2015 (NTG, 2017). The assessment used indicated that the stock declined substantially as a result of the high Taiwanese catches in the 1970s and 1980s. However, the cessation of foreign fishing and more stringent management of the domestic fishery allowed the stock to recover rapidly, with model outputs estimating biomass at 72 per cent of unfished levels in 2015 (NTG, 2017). Despite the decline in catch rate during 2015, NTG (2017) concludes that current biomass levels are well within sustainable limits and conclude that this stock is not recruitment overfished and the current level of fishing mortality is unlikely to cause the stock to become recruitment overfished.  This evidence indicates that it is highly likely that the stock is above the PRI.

Spot-Tail Sharks (Low risk)

The most recent stock assessment of Spot-Tail Sharks including data up to 2011 have estimated current biomass is 93% of the unfished level, with a 96% probability that overfishing is not occurring (Grubert et al. 2013). Tagging studies conducted by the Department of Primary Industry and Fisheries have confirmed this low harvest rate (Bradshaw et al. 2013). This evidence indicates that it is highly likely the stock is above the PRI.

CRITERIA:  (ii) There is a strategy in place that is designed to maintain or to not hinder rebuilding of other species.

(a) Management strategy in place

LOW RISK

The harvest strategy is based on licence limitation (17 in 2017), gear restrictions and total allowable effort. The fishery also has a performance management system with catch trigger points for target species, including a trigger of 30% change in catch for two calendar years. For other non-target, byproduct and bycatch species there is an additional trigger point of an increase or decrease in catch by 50% for more than two consecutive years, monitored through commercial logbooks and observer coverage. If any of these triggers are breached, an appropriate management response is required within 12 months to restrict harvest (NTG 2014). These measures, together with periodic assessments, constitute at least a partial strategy that is expected to maintain the main other species above the PRI. The proposed new Management Plan will have more prescriptive trigger reference point limits related to biomass of the main target, byproduct and bycatch species, as well as a more detailed management response when triggers are reached (DPIF, 2016a).

(b) Management strategy evaluation

LOW RISK

The outcomes of periodic stock assessments (e.g. Grubert et al, 2013; NTG, 2017) provide an objective basis for confidence that the strategy will work given that catches of both species are well under their estimated MSY levels. Moreover, a qualitative ERA undertaken with input from fishery managers and other external experts rated the impact of the fishery as ‘negligible’ on these species, providing an objective basis for confidence that the strategy is effective (NTG 2014).  No specific management actions were proposed for these species as a result of the outcomes of the ERA.

(c) Shark-finning

MEDIUM RISK

Shark finning is prohibited in the ONLF and license conditions require that any shark fin in possession must have an appropriate weight of trunks or shark fillet associated with it.  There has been approximately 5% onboard observer coverage in the fishery since 2007 and there has been no observation of shark finning taking place on any of these trips suggesting it is unlikely to be occurring.  Additional evidence of external validation of vessel activities may result in a lower risk score.

CRITERIA: (iii) Information on the nature and amount of other species taken is adequate to determine the risk posed by the UoA and the effectiveness of the strategy to manage other species.

(a) Information

LOW RISK

Commercial catch and effort for the main other species is reported to the species level in daily logbooks for both species.  This information has been verified by onboard observer coverage, who also monitor the proportion and composition of bycatch (NTG, 2017). The biology of both species including growth, reproductive biology, stock structure and age and longevity is sufficiently well known for both species to produce quantitative assessments (e.g. Grubert et al, 2013).  A tag/recapture program on Blacktip Sharks, including Spot-Tail sharks, has been conducted since 2007, confirming the assessment of high biomass for these species with an associated low harvest rate (Bradshaw et al. 2013).  The available information is sufficient to assess the impact of the fishery on both species, and to support an effective management strategy.

PI SCORE – LOW RISK

2B: Endangered Threatened and/or Protected (ETP) Species

CRITERIA: (i) The UoA meets national and international requirements for protection of ETP species.
The UoA does not hinder recovery of ETP species.

(a) Effects of the UoA on populations/stocks

MEDIUM RISK

NTG (2017) report that the ONLF operates beyond the geographical range of many ETP species and so the risk of interaction with this group of species is low.  Nevertheless, a number of ETP species exist in the area of operation for the ONLF, including sawfish, turtles and dolphins. Data on interactions with ETP species in the fishery has been collected since 2003 as part of the commercial logbook returns process. The prohibition of bottom set nets in the fishery in the mid 2000s has reduced its interaction with ETP species. In 2015, licensees reported interactions with 27 sawfish, 13 turtles, 1 mobulid ray and one dolphin during the course of 588 days of fishing (equating to less than one ETP species interaction per week of fishing) (NTG, 2017). A similar profile of interactions was reported in 2014, with licensees reporting interactions with 22 sawfish, 22 turtles, 15 mobulid rays, two Bronze Whaler Sharks and one dolphin during the course of 621 days of fishing. The number and fate of ETP interactions reported in logbooks is consistent with that recorded during onboard observer trips (NTG, 2016). Logbook reports indicate that most turtles are released alive (NTG, 2014).

An ecological risk assessment (ERA) conducted in 2009 concluded that the level of catch of ETP species would have a negligible or or low impact on their stocks (NTG, 2014).  DoE (2015) report that the fishery is not thought to pose a significant threat to sawfish and river shark species.  Observer coverage of this fishery over 49 days at sea recorded only one capture each of both the northern river shark and the green sawfish (Field et al., 2008).

Two species that weren’t considered in the ERA as ETP species given their recent listing are the Scalloped Hammerhead and Great Hammerhead (included on CITES Appendix II in September 2014 and recognised as protected species under the Commonwealth EPBC Act). In 2011, the ONLF took 141 t of hammerhead shark, however species specific catches are not available and so the exact take of each species is unknown (Simpfendorfer, 2014). NTG (2017) reported that hammerhead sharks accounted for 1% of the 522t retained ONLF catch in 2015.

On the basis of the information available on the populations of these species within Australian waters and within the Oceania region, the CITES Scientific Authority of Australia has found that current levels of Australian catch are unlikely to be detrimental to these species (DoE, 2014). The current catch level accepted as non-detrimental to Scalloped Hammerhead and Great Hammerhead stocks has been capped at 200 t per year and 100 t per year respectively for Australian fisheries. This catch level is unlikely to harm stocks of either species and there is strict management on the take of sharks across northern Australia (e.g. WA Northern Shark Fishery currently being closed, a marked decrease in shark fishing in northern Western Australia over the past 5-8 years). There is evidence of other more heavily exploited species of sharks in northern Australia (Blacktip Sharks) have recovered since being heavily fished by the Taiwanese gillnet fishery in the 1970’s and 1980’s (Bradshaw et al., 2013). DoE (2014) notes that this may also suggest a recovery of Scalloped Hammerheads and Great Hammerheads in the same area.

On the basis of the above, it appears at least likely that the known direct effects of the UoA are likely to not hinder recovery of ETP species.  A key limitation is the relatively low level of observer coverage which may not be able to accurately verify logbook reporting.

CRITERIA: (ii) The UoA has in place precautionary management strategies designed to:

  • meet national and international requirements; and
  • ensure the UoA does not hinder recovery of ETP species.
(a) Management strategy in place

MEDIUM RISK

The measures in place to manage impacts on ETP species comprise limiting entry into the fishery, restricting gear and spatial restrictions. There is a specific performance indicator in the management framework for the fishery that enacts an abatement plan on ETP species within 12 months of identifiable impacts being observed by commercial fishers, NT Fisheries staff or other agencies regarding the EPBC Act listed species (NTG 2014). All ETP species interactions must be reported to Northern Territory Fisheries Division in daily logbook returns. To improve reporting accuracy, fishers have been provided with identification guides for protected Sawfish and Northern River Shark species. Rates of interaction are independently verified by a low level of observer coverage and impacts on ETP species have been assessed qualitatively through an ERA.  To address the recent listing of Scalloped Hammerheads, catches for this species have been limited to within historical levels for the next five years, and they will be reviewed pending any new biological information that is available at this time.

While many of the measures to constitute a strategy are in place, the main limitation is the relatively low level of observer coverage which may not be adequate to accurately verify logbook reporting and may result in poor spatial or temporal representativeness.  Nevertheless, the UoA has measures in place that minimise adverse impacts and are expected to ensure the ensure the UoA does not hinder recovery of ETP species.  Accordingly, we have scored this SI medium risk.

(b) Management strategy implementation                                             LOW RISK

The small number of interactions reported in logbooks and by onboard observers, the low level of effort by the fishery and the outcomes of the ERA (NTG 2014), provide some objective basis for confidence the current measures will work. For Scalloped Hammerheads and Great Hammerheads, the findings of the CITES Non-Detriment Finding (NDF) provide evidence to suggest that current harvests will not hinder recovery (DoE 2014).

CRITERIA: (iii) Relevant information is collected to support the management of UoA impacts on ETP species, including:

  • information for the development of the management strategy;
  • information to assess the effectiveness of the management strategy; and
  • information to determine the outcome status of ETP species.
(a) Information

MEDIUM RISK

ETP species interactions are required to be recorded by fishers in commercial logbooks and are verified to some extent through a low level (5% of total effort) of onboard observer coverage (NTG, 2017). The biology of most ETP species interacted with, including stock structure, is well known (e.g. Peverell 2008, Pillans et al. 2009, Phillips et al. 2011; DoE, 2014).  A qualitative (ERA) conducted in 2009 concluded that the level take of ETP species would have a negligible impact on their stocks (NTG 2014).  Accordingly, some quantitative information is available and has been adequate to assess, at least at a quantitative level, the likely impact of the fishery on ETP species.  Nevertheless, the low level of observer coverage may not be sufficient to accurately validate reporting of ETP interactions in logbooks.  Accordingly, we have scored this SI medium risk.

PI SCORE –  MEDIUM RISK

2C: Habitats

CRITERIA: (i) The UoA does not cause serious or irreversible harm to habitat structure and function, considered on the basis of the area(s) covered by the governance body(s) responsible for fisheries management

(a) Habitat status

LOW RISK

Pelagic gillnets are not allowed to be ‘bottom set’ so rarely make any contact with the seabed. Additionally, the fishery is only allowed to operate seaward from the 3nm mark which limits the amount of shallow, coastal habitat that can be interacted with.  Accordingly, the fishery is highly unlikely to reduce habitat structure and function to the point of serious or irreversible harm.

CRITERIA:  (ii) There is a strategy in place that is designed to ensure the UoA does not pose a risk of serious or irreversible harm to the habitats.

(a) Management strategy in place

LOW RISK

The main measure in place to limit the impacts of the fishery on habitats is the prohibition on bottom set gillnets.  Additional restrictions include limited entry, effort limits (TAE), gear restrictions (e.g. net length), and spatial restrictions. There is also a specific performance indicator in the management framework for the fishery that enacts a management response to mitigate habitat interactions within 12 months of identifiable impacts on habitat being reported (NTG 2014).  Given the absence of substantive contact between the gear and benthic habitats, these measures constitute a strategy that is expected to achieve the outcome stated in criterion 2C(i).

(b) Management strategy implementation

LOW RISK

Given the pelagic nature of the gear, there is an objective basis for confidence that the management strategy will work and the absence of systemic compliance problems in the fishery (NTG, 2017) indicates that the strategy is being implemented effectively.

CRITERIA: (iii)  Information is adequate to determine the risk posed to the habitat by the UoA and the effectiveness of the strategy to manage impacts on the habitat.

(a) Information quality

LOW RISK

The nature, distribution and vulnerability of habitat types within Australia’s northern region has been characterised and mapped over several decades with much of the information compiled to support recent marine reserve planning (e.g. DEWHA, 2007). Locations of fishing activity are well-known through logbook reporting and observer coverage.  Given the pelagic nature of the fishing gear, the available information on habitats is known at a level of detail consistent with the nature and scale of the fishery.

(b) Information and monitoring adequacy

LOW RISK

Information is adequate to broadly understand the nature of the main impacts of gear use on the main habitats, including spatial overlap of habitat with fishing gear. While the impacts of gillnets on habitat haven’t been explored explicitly the physical impacts of this passive gear type is likely to be low, particularly considering that the gillnets used in the fishery are pelagic and rarely make contact with the seabed.

PI SCORE – LOW RISK

2D: Ecosystems

CRITERIA: (i) The UoA does not cause serious or irreversible harm to the key elements of ecosystem structure and function.

(a) Ecosystem Status

LOW RISK

Given the apparent relatively limited impact on ETP species and habitats, the main ecosystem impacts from the fishery are likely to come from the removal of target and byproduct species from the ecosystem.  In particular, the removals of top order predators such as sharks is suggested to significantly impact marine food webs (e.g. Myers et al. 2007). However, current biomass estimates for the target shark species are at approximately 80% of unfished levels (Johnson et al. 2016a). Although there is uncertainty about the status of Blacktip Sharks stock in the Gulf of Carpentaria, the ONLF accounts for a very small proportion of the overall catch of this stock.  Moreover, stocks of Grey Mackerel, Spanish Mackerel and Spot-Tail Sharks are all estimated to be at levels well within sustainable limits.  An ERA conducted on the fishery in 2009 indicated that the harvest rates of most species are at levels that have a negligible impact on the stock (NTG 2014). Consequently, there appears to be sufficient indirect evidence to suggest that the fishery is highly unlikely to disrupt the key elements underlying ecosystem structure and function to the point of serious or irreversible harm.

CRITERIA:  (ii) There are measures in place to ensure the UoA does not pose a risk of serious or irreversible harm to ecosystem structure and function.

(a) Management strategy in place

LOW RISK

The main measures in place to ensure that the fishery does not pose a risk of serious or irreversible harm to ecosystem structure and function, including limited entry, effort limits (TAE), gear restrictions, spatial restrictions and closures. There is also a specific performance indicator in the management framework for the fishery that enacts a management response to mitigate ecosystem impacts within 12 months of identifiable impacts being reported (NTG 2014).  Ecological risks associated with the fishery have been assessed, and periodic stock assessments of the main target species are likely to provide some indication of increased risk.  These measures are likely to constitute at least a partial strategy that could be expected to limit the impacts of the fishery so as to achieve the outcome sated in criteria 2D(i).

(b) Management strategy implementation

LOW RISK

The qualitative ERA undertaken in 2009 provides some objective basis for confidence that the impact of the fishery on the broader ecosystem is likely to be low, and the outcomes of quantitative assessments of key species provide some quantitative evidence that the strategy is being implemented effectively.   The effectiveness of the strategy is also evaluated at least annually through the DPIF Stock Status reporting process as well as periodically through the ONLAG (NTG 2015). The very high biomass levels of target and bycatch species relative to unfished biomass provides additional confidence that the fishery is unlikely to be causing serious or irreversible harm to the key elements of the ecosystem.

CRITERIA: (iii) There is adequate knowledge of the impacts of the UoA on the ecosystem.

(a) Information quality

LOW RISK

The structure and function of the main elements of the northern Australian ecosystem have been relatively well studied, with much of the information compiled to support marine reserve planning processes (e.g. NOO, 2004; Australian Museum, 2005; DEWHA, 2007; 2008a; 2008b) or fisheries management (e.g. Bustamante et al, 2010). This information includes a significant amount of data on ecology of shark species (e.g. Simfendorfer and Milward 1993, Harry et al. 2011).  Information supplied in compulsory catch and effort logbooks, periodic observer coverage and periodic assessments of target species is sufficient to detect increased risk from the UoA.

(b) Investigations of UoA impact

MEDIUM RISK

The main impacts of the fishery on the ecosystem are likely to be largely limited to the removal of the shark target species.  There has been a substantial body of research on the impacts of removing top order predators such as sharks (e.g. Myers et al, 2007, Stevens et al. 2000), but no dedicated investigations of the ecosystem impacts of the ONLF specifically. Accordingly, the main impacts of the fishery on key ecosystem elements is likely to be able to be inferred from existing information, but have not been investigated in detail.

 

PI SCORE – LOW RISK

COMPONENT 3: Management system

3A: Governance and Policy

CRITERIA: (i) The management system exists within an appropriate and effective legal and/or customary framework which ensures that it:

  • Is capable of delivering sustainability in the UoA(s), and;
  • Observes the legal rights created explicitly or established by custom of people dependent on fishing for food or livelihood.
(a) Compatibility of laws or standards with effective management

LOW RISK

The fishery is managed by the Northern Territory Fisheries Joint Authority (NTFJA), under an Offshore Constitutional Settlement (OCS) arrangement between the Northern Territory and the Commonwealth.  Day- to-day management is undertaken by the Department of Primary Industries and Resources (DPIR) in accordance with the NT Fisheries Act 1988 and subordinate legislation including the NT Fisheries Regulations.  The Northern Territory/NTFJA management and legislative framework is consistent with local, national or international laws or standards that are aimed at achieving sustainable fisheries.

(b) Respect for Rights

LOW RISK

Customary rights of Aboriginal people are recognised in the Northern Territory. The Blue Mud Bay agreement has resulted in waters overlying aboriginal land to the low tide mark having access controlled by the aboriginal communities in that area. Customary harvest by traditional means has no limitations in the NT Fisheries Act. The rights of customary fishers are recognised by the s53 exemption which provides that: Unless and to the extent to which it is expressed to do so but without derogating from any other law in force in the Territory, nothing in a provision of this Act or an instrument of a judicial or administrative character made under it shall limit the right of Aboriginals who have traditionally used the resources of an area of land or water in a traditional manner from continuing to use those resources in that area in that manner.  Additional customary rights may be sought under Commonwealth Native Title legislation.

CRITERIA: (ii) The management system has effective consultation processes that are open to interested and affected parties. The roles and responsibilities of organisations and individuals who are involved in the management process are clear and understood by all relevant parties.

(a) Roles and Responsibilities

LOW RISK

The roles and responsibilities of the main people (e.g. NTFJA, Fisheries Ministers, Director of Fisheries) and organisations (Amateur Fishermen’s Association of the Northern Territory – AFANT; Northern Territory Seafood Council – NTSC; Northern Land Council – NLC) involved in the Northern Territory fisheries management process are well-understood, with relationships and key powers explicitly defined in legislation.

(b) Consultation Process

LOW RISK

Consultation on management arrangements is primarily undertaken through the Offshore Net and Line Advisory Group (ONLAG), comprising members from industry, recreational and FTO representatives, compliance and departmental officers.  ONLAG was established in 2013 to develop a comprehensive policy and management framework.  Formal consultation is also undertaken through the NTSC and the ONLF Fishermen’s Association.  NT Fisheries also produces publications, such as Fishery Reports, Fishnotes and newsletters, to inform stakeholders (e.g. NTG 2017).  Where significant management changes are proposed, public consultation documents are developed (e.g. the newly proposed management arrangements document to support the new quota system).

CRITERIA: (iii) The management policy has clear long-term objectives to guide decision making that are consistent with Components 1 and 2, and incorporates the precautionary approach.

(a) Objectives

LOW RISK

The management objectives for all Northern Territory Fisheries as outlined in the NT Fisheries Act 1988 are to “conserve, enhance, protect, utilise, and manage the fish and aquatic life resources of the Territory to:

(a) Promote, develop and maintain commercial and amateur fishing;

(b) Provide for optimum yields from a fishery and maintain the quality of the yield;

(c) Ensure that the fisheries of the Territory are not endangered or overexploited;

(d) Encourage tourist and scientific interest in fish and aquatic life; and/or

(e) Ensure that the habitats of fish or aquatic life and the general environment is not detrimentally affected“.

These objectives are consistent with the outcomes expressed in Components 1 and 2.

PI SCORE – LOW RISK

3B: Fishery Specific Management System

CRITERIA:  (i) The fishery specific management system has clear, specific objectives designed to achieve the outcomes expressed by Components 1 and 2.

(a) Objectives

MEDIUM RISK

There are no fishery specific objectives set in management arrangements, although Components 1 and 2 are implicitly supported by constraining catch of target and non-target species by all sectors. Management arrangements are currently being revised and the revised management plan is expected to contain both long term and short term objectives of the fishery as well as including a more contemporary harvest strategy framework.

CRITERIA:  (ii) The fishery specific management system includes effective decision making processes that result in measures and strategies to achieve the objectives .

(a) Decision making

LOW RISK

The NTFJA and DPIF fisheries decision making process is well-established, and there is evidence through EPBC reviews that the management system is broadly meeting its stated objectives.  The NTFJA has ultimate responsibility for the management of the fishery, and is empowered to make decisions in relation to the fishery, to be implemented by DPIF under the NT Fisheries Act 1988.   The NTFJA is advised by DPIF who, in turn, seek input from stakeholders and technical experts.    The decision making process appears to respond to serious or other important issues in a timely and transparent manner. The elimination of bottom set gillnets in the fishery during the early 2000s to limit interactions with ETP species such as sawfish is evidence of the decision making process responding to issues raised through fishery consultative processes. Similarly, the establishment of a new management framework which triggers management responses provides a structured process to respond to research and monitoring outcomes.

(b) Use of the Precautionary approach LOW RISK

While the precautionary approach is not explicitly required in the NT Fisheries Act, there is evidence that managers use a precautionary approach in practice where there is scientific or other uncertainty.  For example, despite the very low harvest rates on the target species there have been examples of the precautionary approach being used including: introducing conservative recreational possession limits, capping the commercial harvest of sharks and modifying gear so as to reduce the likelihood of ETP interactions.

(c) Accountability and Transparency

LOW RISK

Information on the biological, ecological and economic performance of the fishery is reported annually through the Department’s Stock Status Reports e.g. (NTG 2017).  Information on recent changes to management and new scientific or monitoring results are provided in the report as well as being discussed with stakeholders during annual meetings and through the ONLAG process.  Relevant research reports are made available on the DPIR website and the website of research funders (e.g. FRDC).  These arrangements are consistent with the low risk SG.  However, some important management and assessment documents (e.g. the framework of monitoring trigger points, the 2009 ERA) are not published on the DPIR website.  The UoA would be more securely positioned against the low risk scoring guidepost if these documents were made publically available.

CRITERIA: (iii) Monitoring, control and surveillance mechanisms ensure the management measures in the fishery are enforced and complied with.

(a) MCS Implementation

LOW RISK

Compliance activities for the Offshore Net and Line Fishery management arrangements are undertaken by the Marine and Fisheries Enforcement Section (MFES) of the NT Police, Fire and Emergency Services, under the NT Fisheries Act 1988. MFES effectively monitors and enforces management arrangements for the ONLF through the inspection of vessel arrivals and departures through the single port of Darwin. This includes verification of catch returns against processor returns (i.e., requirement for all operators to specify where they are selling their product). MFES has the power, if necessary, to investigate the records of wholesalers and licensees.  NTG (2017) reports that here have been few reported problems with compliance in the ONLF.

The main source of illegal shark catch in Australia’s northern waters in recent times has come from small-scale Indonesian fishers illegally targeting sharks for fins (e.g. Salini et al, 2007; Marshall, 2011). The number of apprehensions of illegal vessels rose steadily from the early 2000s, peaking in 2005-06 at 368 apprehensions (Marshall, 2011).  Based on numbers and species composition from a sample of apprehended Indonesian vessels, Marshall (2011) estimated that the total illegal harvest of sharks by Indonesian vessels in 2006 (the peak calendar year of illegal activity) was 680t, with species in the Blacktip Shark complex (C. tilstoni, C. limbatus) accounting for about 17% of the catch.  Apprehensions have substantially decreased with only 27 apprehensions in the 2008-2009 financial year.  The decrease in illegal activity has been attributed to a number of factors including increased border security by the Australian Government, the global financial crisis, high petrol prices and new domestic Indonesian policies (Marshall, 2011).   Illegal catches are accounted for in stock assessments (e.g. Grubert et al, 2013).

(b) Sanctions and Compliance

LOW RISK

Sanctions to deal with non-compliance exist and appear to be consistently applied, although few instances of compliance breaches by Australian vessels have been found (NTG, 2017).  Compliance issues are reported periodically through the Fishery Status Reports.  The available evidence suggests there is good confidence that fishers comply with the management system under assessment.

CRITERIA: (iv) There is a system for monitoring and evaluating the performance of the fishery specific management system against its objectives.
There is effective and timely review of the fishery specific management system.

(a) Evaluation coverage

LOW RISK

The performance of the management system is evaluated through periodic stock assessments, as well as against a framework of trigger points designed to identify trends that require management attention.   The effectiveness of the compliance regime is evaluated through periodic risk assessments conducted by the NT Water Police.  Accordingly, mechanisms are in place to evaluate key parts of the management system.

(b) Internal and/or external review

LOW RISK

The management system is internally reviewed at least every five years under the Department’s Strategic Planning process.  A new harvest strategy is currently being developed for the fishery which will require regular internal review of performance against reference points which will further strengthen this system.  The fishery is also subject to periodic external review through the Commonwealth EPBC export accreditation process.  The fishery is currently undergoing its fourth assessment.

PI SCORE – LOW RISK

Acknowledgements

T​his seafood risk assessment procedure was originally developed for Coles Supermarkets Australia by MRAG Asia Pacific. FRDC is grateful for Coles’ permission to use its Responsibly Sourced Seafood Framework.

​It uses elements from the GSSI benchmarked MSC Fishery Standard version 2.0, but is neither a duplicate of it nor a substitute for it. The methodology used to apply the framework differs substantially from an MSC Certification.  Consequently, any claim about the rating of the fishery based on this assessment should not make any reference to the MSC.