Chapter 21: Eastern Tuna and Billfish Fishery
J Larcombe, H Patterson and J Savage
TABLE 21.1 Status of the Eastern Tuna and Billfish Fishery
| Fishing mortality|| Biomass||Fishing mortality||Biomass|| |
|Striped marlin (Kajikia audax), south-west Pacific||Not subject to overfishing||Not overfished||Not subject to overfishing||Not overfished||Most recent estimate of spawning biomass (2012) is above the default limit reference point of B20 but below BMSY. Current fishing mortality rate is below MSY levels.|
|Swordfish (Xiphias gladius), south-west Pacific||Uncertain||Not overfished||Not subject to overfishing||Not overfished||Most recent estimate of biomass (2017) is likely above the default limit|
reference point. Recent fishing mortality is likely below FMSY.
|Albacore (Thunnus alalunga), south Pacific||Not subject to overfishing||Not overfished||Not subject to overfishing||Not overfished||Most recent estimate of spawning biomass (2015) is above the default limit reference point. Recent ocean-wide catches are at, or slightly less than, MSY, and fishing mortality is below MSY levels.|
|Bigeye tuna (Thunnus obesus), western and central Pacific||Subject to overfishing||Overfished||Not subject to overfishing||Not overfished||Most recent estimate of spawning biomass (2017) is likely above the limit reference point. Recent fishing mortality is likely below FMSY.|
|Yellowfin tuna (Thunnus albacares), western and central Pacific||Not subject to overfishing||Not overfished||Not subject to overfishing||Not overfished||Most recent estimate of biomass (2017) is highly likely above the limit reference point. Oceanwide estimates of fishing mortality are highly likely below FMSY.|
|Economic status||NER for the fishery improved significantly in 2014–15, rising to $6.7 million. Preliminary estimates suggest that this improvement in economic performance will be sustained in 2015–16 and 2016–17, driven by increased catch, higher prices of key species and a significant fall in fuel price.|
a Regional assessments of species and the default limit reference points from the Commonwealth Fisheries Harvest Strategy Policy (DAFF 2007) are used as the basis for status determination.
B20 20% of unfished biomass. BMSY Biomass at MSY. MSY Maximum sustainable yield.
NER Net economic returns.
21.1 Description of the fishery
The Eastern Tuna and Billfish Fishery (ETBF) operates in the Exclusive Economic Zone, from Cape York to the Victoria – South Australia border, including waters around Tasmania and the high seas of the Pacific Ocean (Figure 21.1). Domestic management arrangements for the ETBF are consistent with Australia’s commitments to the Western and Central Pacific Fisheries Commission (WCPFC; see Chapter 20).
Fishing methods and key species
Key species in the ETBF are shown in Table 21.1. Most of the catch in the fishery is taken with pelagic longlines, although a small quantity is taken using minor-line methods (Table 21.2). Some ETBF longliners catch southern bluefin tuna (Thunnus maccoyii)off New South Wales during winter, after fishing for tropical tunas and billfish earlier in the year, while others take them incidentally when targeting other tunas. All southern bluefin tuna taken must be covered by quota and landed in accordance with the Southern Bluefin Tuna Fishery Management Plan 1995. Recreational anglers and game fishers also target tuna and marlin in the ETBF. Many game fishers tag and release their catch, especially marlins. The retention of blue marlin (Makaira mazara)and black marlin (M. indica)has been banned in commercial fisheries since 1998, and catch limits have been introduced on longtail tuna (T. tonggol),in recognition of the importance of these species to recreational anglers.
The primary ETBF tuna and billfish species are managed through total allowable catches allocated as individual transferable quotas (ITQs). The Commonwealth Fisheries Harvest Strategy Policy (HSP; DAFF 2007) is not prescribed for fisheries managed under international agreements. However, a harvest strategy framework has been developed for the ETBF (Campbell 2012). The framework has been used to set the total allowable commercial catch (TACC) for swordfish (Xiphias gladius)and striped marlin (Kajikia audax)since 2011, but is not currently used for tuna species.
Australia’s catch in the ETBF as a percentage of the total catch from all nations in the Coral and Tasman seas has been declining across the major target species. This is due primarily to an increase in the catch by other nations for some species. The Tropical Tuna Resource Assessment Group (TTRAG) noted that the ETBF catch as a proportion of the total catch in the Coral and Tasman seas was relatively high for swordfish and striped marlin, and that the ETBF harvest strategy would therefore be effective. In 2013, TTRAG made some adjustments to the target reference catch rates used in the ETBF harvest strategy for swordfish and striped marlin. These provide better alignment with the HSP default reference points of 48 per cent of unfished biomass (B48) for the target and 20 per cent of unfished biomass (B20) for the limit.
In 2013, TTRAG found that the ETBF harvest strategy was not likely to achieve its objectives according to the requirements of the HSP for bigeye tuna (T. obesus), yellowfin tuna (T. albacares)and albacore (T. alalunga). Australia’s catch of these species was low as a proportion of total regional catch, and, under these circumstances, changes to Australia’s catch could not be expected to result in a change in the stock status (because of a lack of feedback to the stock as a whole).
The Australian Fisheries Management Authority (AFMA) Commission subsequently directed TTRAG to cease using the harvest strategy to calculate recommended biological commercial catch levels for bigeye tuna, yellowfin tuna and albacore, and to prepare information on stock status of tunas. In the absence of an accepted harvest strategy, and because there has been no allocation of tuna catches by the WCPFC, AFMA has applied TACCs based on historical catch levels in the fishery, and in accordance with any limits determined by the WCPFC or agreed through regional arrangements.
The status of ETBF tuna and billfish is derived from the regional assessments undertaken for the WCPFC. Assessment results over the relevant geographic area modelled are used to determine stock status, but supplementary management advice may also be derived from the region most relevant to Australia. The WCPFC has agreed limit reference points for some stocks, but, where agreed limit reference points are absent, status determination was informed by the proxies specified in the HSP.
In 2017, the WCPFC Scientific Committee adopted a number of key changes to the way it treats uncertainty in the stock assessments and communicates that uncertainty. Management statistics and stock status are based on a structural uncertainty grid that incorporates all plausible models across all combinations of key uncertainty axes (for example, steepness, natural mortality, growth, tagging parameters). The structural uncertainty grid may comprise a large number of separate models (generally up to 72) that may be weighted (or even removed entirely) when some axis settings are less plausible than others. The various management quantities are then expressed as the median of the grid, with a range of uncertainty around that median. There will also be a probability (or a proxy of the probability) associated with breaching each of the key reference points (for example, percentage of the grid models where recent spawning biomass was below the limit reference point). This uncertainty also extends to the statements on ‘overfished’ and ‘overfishing’, which are now more nuanced (for example, ‘likely’ or ‘very likely’). The status information in this chapter for bigeye tuna, yellowfin tuna and swordfish all reflect this change.
From 1 July 2015, electronic monitoring has been mandatory for all full-time pelagic longline vessels in the ETBF and the Western Tuna and Billfish Fishery. At least 10 per cent of video footage of all hauls is reviewed to verify the accuracy of logbooks, which must be completed for 100 per cent of shots.
The number of active vessels in the fishery (Figure 21.2) has decreased substantially in the past decade (from around 150 in 2002 to 39 in 2017), probably as a result of a decline in economic conditions in the fishery and the removal of vessels through the Securing our Fishing Future structural adjustment package in 2006–07 (Vieira et al. 2010).
Following a decrease in effort, the total retained catch of all species in the ETBF declined from a high of more than 8,000 t in 2002 to around 4,200 t in 2013. Catch declined in 2017 to 4,615 t from 5,143 t in 2015 (Figure 21.3). Swordfish and yellowfin tuna continue to be the main target species.
TABLE 21.2 Main features and statistics for the ETBF
Real value (2015–16)
Real value (2016–17)
|Striped marlin||351||244||$1.4 million||351||286||$1.0 million|
|Swordfish||1,373||1,161||$9.2 million||1,285||1,175||$9.3 million|
|Albacore||2,500||1,101||$3.9 million||2,500||992||$4.1 million|
|Bigeye tuna||1,056||872||$8.1 million||1,056||449||$7.3 million|
|Yellowfin tuna||2,200||1,765||$25.1 million||2,400||1,713||$12.6 million|
Total fishery||7,480||5,143||$49.6 million||7,592||4,615||$35.7 million|
|Effort||Longline: 7.82 million hooks
Minor line: na
|Longline: 8.73 million hooks
Minor line: na
|Fishing permits||Longline boat SFRs: 86
Minor-line boat SFRs: 93
|Longline boat SFRs: 85
Minor-line boat SFRs: 93
|Active vessels||Longline: 37
Minor line: 2
Minor line: 2
|Observer coverage||Longline: 8.7%
Minor line: 0
Minor line: 0
|Fishing methods||Pelagic longline, minor line (trolling, rod and reel, handline)|
|Primary landing ports||Bermagui, Coffs Harbour and Ulladulla (New South Wales); Cairns, Mooloolaba and Southport (Queensland)|
|Management methods||Output controls: TACCs and ITQs
Input controls: limited entry, gear restrictions
|Primary markets||Domestic: fresh
International: Japan, United States—mainly fresh; Europe—frozen; Indonesia, American Samoa, Thailand—albacore mainly for canning
|Management plan||Eastern Tuna and Billfish Fishery Management Plan 2010|
a Fishery statistics are provided by calendar year to align with international reporting requirements. Real-value statistics are by financial year and are expressed in 2016–17 dollars. Total real value includes value from non-quota species caught in the ETBF.
b From 1 July 2015, electronic monitoring is mandatory for all full-time pelagic longline vessels in the ETBF. At least 10% of video footage of all hauls is reviewed to verify the accuracy of logbooks, which must be completed for 100% of shots. The percentage of hooks observed is provided.
ITQ Individual transferable quota. na Not available.
SFR Statutory fishing right.
TACC Total allowable commercial catch.
21.2 Biological status
Striped marlin (Kajikia audax)
Line drawing: FAO
Genetic studies have identified multiple stocks of striped marlin in the Pacific Ocean (for example, McDowell & Graves 2008; Purcell & Edmands 2011). As a result, the north Pacific Ocean and south-west Pacific Ocean (SWPO) stocks are assessed separately (WCPFC 2013). Information for the SWPO stock is reported here.
Catch for the ETBF increased slightly in 2017 to 286 t (Figure 21.4), while catch in the south Pacific decreased from 2,110 t in 2015 to 1,801 t in 2016 (Figure 21.5). An increase in the south Pacific catch in 2011–12 was driven in part by increases in catch in the north that are not subject to the current conservation and management measure (CMM) for striped marlin—WCPFC CMM 2006-04—which only applies south of 15°S.
Stock status determination
The most recent estimate of the SWPO spawning biomass of striped marlin is above the WCPFC limit reference point of 20 per cent of the levels predicted to occur in the absence of fishing. The most recent base-case estimates of fishing mortality and most sensitivity analyses are below the level associated with MSY; however, recent catches are somewhat above the estimated MSY level. SWPO striped marlin is classified as not subject to overfishing and not overfished. The recent catch levels and the age of the stock assessment both contribute to increased uncertainty around the stock status of striped marlin in 2016. This trend in catch is likely to affect future status determination. The Scientific Committee of the WCPFC recommended measures to control overall catch, through expansion of the geographical scope of CMM 2006-04 to cover the distribution of the stock; the WCPFC has not yet adopted this recommendation.
Swordfish (Xiphias gladius)
Line drawing: Gavin Ryan
Although studies of swordfish have generally indicated a low level of genetic variation in the Pacific Ocean (Kasapidis et al. 2008), the WCPFC assesses two stocks separately: a north Pacific stock and an SWPO stock. The information reported here is for the SWPO stock.
Swordfish catch in the ETBF increased slightly in 2016 (Figure 21.6). Catch in the south Pacific has generally been increasing since 2001, but decreased slightly in 2016 to 22,890 t (Figure 21.7).
The SWPO stock of swordfish was most recently assessed in 2017 using the assessment package MULTIFAN-CL (Takeuchi, Pilling & Hampton 2017). The stock assessment is based on a structural uncertainty grid that includes steepness, size data weighting, diffusion rate and natural mortality as the main uncertainties. The uncertainty grid using this approach contained 72 related models. The WCPFC Scientific Committee agreed to use the full grid, with equal weighting for all axes of uncertainty. Note that the primary uncertainty in the 2013 assessment (Davies et al. 2013), relating to growth and maturity schedules, has been resolved based on new research (Farley et al. 2016).
Across all models in the uncertainty grid, the spawning biomass declines steeply between the late 1990s and 2010, but the rate of decline has been less since then. These declines are greater in the eastern Region 2 (equator to 50°S, 165°E to 130°W), where fishing mortality is also greater than in the western Region 1 where the Australian fishery operates.
The median recent spawning stock biomass was 35 per cent of the levels predicted to occur in the absence of fishing (SBrecent/SBF=0 = 0.35; 80 per cent probability interval = 0.29–0.43). There was a very low probability that the recent spawning stock biomass has breached the limit reference point. The median recent fishing mortality was 86 per cent of the fishing mortality associated with MSY (Frecent/FMSY = 0.86; 80 per cent probability interval = 0.51–1.23). There was a roughly 32 per cent probability that the recent fishing mortality was above FMSY.
Stock status determination
Based on the uncertainty grid, the spawning biomass is likely above the limit reference point of 20%SBF=0 adopted for tunas. As a result, the swordfish stock in the SWPO is classified as not overfished. Recent fishing mortality is also likely below FMSY. The stock is therefore classified as not subject to overfishing.
Albacore (Thunnus alalunga)
Line drawing: FAO
Two distinct stocks of albacore (north Pacific and south Pacific) are found in the Pacific Ocean, generally associated with the two oceanic gyres. These two stocks are assessed separately (WCPFC 2015). Information for the south Pacific albacore stock is reported here.
Catches in the ETBF decreased slightly to 992 t in 2017 (Figure 21.8). Catches in the south Pacific have been stable in recent years, but decreased in 2016 to 68,449 t (Figure 21.9). The WCPFC Scientific Committee recommended that longline fishing mortality be reduced if the WCPFC’s goal is to maintain economically viable catch rates.
The assessment for albacore in the south Pacific was updated in 2015 using MULTIFAN-CL (Harley et al. 2015). Substantial improvements in the 2015 stock assessment included improvements to the MULTIFAN-CL modelling framework, use of a regional disaggregated framework, use of operational data for construction of CPUE indices and regional weights, changes to some key biological parameters, inclusion of direct age-at-length data to improve growth estimation, and inclusion of additional tagging data (Harley et al. 2015). Two influential changes were a change in the natural mortality assumption (from 0.4 to 0.3 per year) and exclusion of the eastern Pacific from the assessment. Although the results of the assessment are broadly consistent with the 2012 assessment, the changes to the assessment combined with the additional years of fishing resulted in a more pessimistic picture, with substantially lower biomass and higher fishing mortality.
The base-case model in the assessment estimated that the latest (2013) spawning biomass was above the level associated with MSY (SBLATEST/SBMSY = 2.86; range 1.74–7.03) and above the adopted limit reference point (SBLATEST/SBF=0 = 0.40; range 0.30–0.60). It should be noted that the estimate of the biomass at MSY (BMSY) for south Pacific albacore is around 14 per cent of unfished levels, which is below the adopted limit reference point of 20 per cent—a target of BMSY would be inconsistent with the adopted limit reference point. Current (2009–2012 average) fishing mortality is below FMSY (FCURRENT/FMSY = 0.39; range 0.13–0.62), and recent catches are likely at, or slightly less than, estimates of MSY.
Stock status determination
The most recent estimate of spawning biomass is above the default limit reference point of 20 per cent of initial unfished levels. The most recent estimates of fishing mortality are well below the levels associated with MSY, and recent catches are around MSY. As a result, albacore in the south Pacific Ocean is classified as not subject to overfishing and not overfished.
Bigeye tuna (Thunnus obesus)
Line drawing: FAO
Genetic data have indicated that bigeye tuna in the Pacific Ocean is a single biological stock (Grewe & Hampton 1998).
Catches of bigeye tuna decreased in the ETBF in 2017, from 872 t in 2016 to 449 t (Figure 21.10). Catches increased in the WCPFC area in 2016 (Figure 21.11). Recent bigeye tuna catch in the WCPFC area (150,884 t in 2016) is close to the estimated MSY (median 158,040 t). Catch has been close to, and occasionally substantially above, this level since around 1997 (Figure 21.11).
The bigeye tuna stock in the western and central Pacific Ocean (WCPO) was most recently assessed in 2017 (McKechnie, Pilling & Hampton 2017) using the assessment package MULTIFAN-CL. The assessment incorporated significant and influential alternative inputs for growth and the regional structure, as well as a range of other improvements and additions. The stock assessment is based on a structural uncertainty grid that includes steepness, growth, maturity, tagging dispersion, size data weighting and regional structure as the main uncertainties. The uncertainty grid using this approach contained 72 related models. The WCPFC Scientific Committee agreed to use the full grid, with a higher weighting given to models using a new bigeye growth curve (75 per cent), a lower weighting given to models using the old assumed growth curve (25 per cent), and equal weighting for all other axes. The updated assessment result is more optimistic with respect to biomass and fishing mortality status (as a result of the inclusion of the new growth curve, new regional structures and increased recruitment), but there is much greater uncertainty around stock status, primarily due to retention of the (albeit down-weighted) old growth models within the grid. A revised assessment will be undertaken in 2018 using a further refined and updated growth curve based on new research. This new assessment should reduce the uncertainty in the current assessment.
The median recent spawning biomass was 32 per cent of the levels predicted to occur in the absence of fishing (SBrecent/SBF=0 = 0.32; 80 per cent probability interval = 0.15–0.41). There was a roughly 16 per cent probability that the recent spawning stock biomass had breached the limit reference point. The median recent fishing mortality was 83 per cent (Frecent/FMSY = 0.83; 80 per cent probability interval = 0.61–1.31). There was a roughly 23 per cent probability that the recent fishing mortality was above FMSY.
Stock status determination
Based on the uncertainty grid, the spawning biomass is likely to be above the limit reference point of 20%SBF=0 adopted for tunas. As a result, the stock is classified as not overfished.Similarly, recent fishing mortality is likely to be below FMSY. As a result, the stock is classified as not subject to overfishing.
Yellowfin tuna (Thunnus albacares)
Line drawing: FAO
Yellowfin tuna in the WCPO is currently considered to be a single biological stock (Langley, Herrera & Million 2012). However, a recent study using newer genomic techniques provided strong evidence of genetically distinct populations of yellowfin tuna at three sites (Coral Sea, Tokelau and California) across the Pacific Ocean (Grewe et al. 2015). Further work is underway to confirm and expand on this initial study.
Catch decreased in the ETBF in 2017 (Figure 21.12). In the wider WCPFC area, the 2016 catch was more than the 2015 catch, at 649,446 t (Figure 21.13), which is below the estimated MSY (median 670,800 t).
The yellowfin tuna stock in the WCPO was most recently assessed in 2017 (Tremblay-Boyer et al. 2017) using the assessment package MULTIFAN-CL. The stock assessment is based on a structural uncertainty grid that includes steepness, tagging dispersion, tag mixing, size frequency and regional structure as the main uncertainties. The uncertainty grid using this approach contained 48 related models. The WCPFC Scientific Committee agreed to use the full grid, with equal weighting for all axes of uncertainty.
The median recent spawning stock biomass was 33 per cent of the levels predicted to occur in the absence of fishing (SBrecent/SBF=0 = 0.33; 80 per cent probability interval = 0.20–0.41). There was a roughly 8 per cent probability that the recent spawning stock biomass had breached the limit reference point. The median recent fishing mortality was 74 per cent (Frecent/FMSY = 0.74; 80 per cent probability interval = 0.62–0.97). There was a roughly 4 per cent probability that the recent fishing mortality was above FMSY.
Stock status determination
Based on the uncertainty grid, the spawning biomass is highly likely to be above the limit reference point of 20%SBF=0 adopted for tunas. As a result, the stock is classified as not overfished.Similarly, recent fishing mortality is highly likely to be below FMSY. As a result, the stock is classified as not subject to overfishing.
21.3 Economic status
Key economic trends
ABARES has conducted economic surveys of the ETBF since the early 1990s. The survey data are used to estimate the level of net economic returns (NER) earned in the fishery. The most recent survey results for the ETBF cover the 2013–14 and 2014–15 financial years. Non–survey based estimates for economic performance are available for the 2015–16 and 2016–17 financial years.
NER in the ETBF were negative between 2002–03 and 2009–10 but generally improved from 2003–04. In 2010–11, the fishery achieved positive NER, driven primarily by reduced operating costs (Mobsby & Bath 2018; Figure 21.14). For the latest survey years (2013–14 and 2014–15), NER in the fishery are estimated to have increased from –$0.6 million in 2013–14 to $6.7 million in 2014–15. The increase in NER in 2014–15 was driven by fishing income increasing at a greater rate than fishing costs, and was supported by an improvement in fishers’ terms of trade and an increase in productivity.
Preliminary non–survey based estimates of NER for 2015–16 show an increase to $15.7 million. Higher NER in 2015–16 were supported by an increase in estimated income, driven largely by a 34 per cent increase in yellowfin tuna catch in that year. Higher beach prices for several targeted species and lower fuel prices are key drivers for the significant increase in NER in 2015–16. The decline in NER in 2016–17 was largely the result of a significant decline in fishing income. The estimated reduction in fishing income in 2016–17 was largely the result of lower yellowfin tuna catch in 2016–17 financial year compared with the 2015–16 financial year.
The real gross value of production in the ETBF decreased by 28 per cent in 2016–17 to $39 million (Figure 21.15). This decline was largely the result of yellowfin tuna catch more than halving to 1,159 tonnes. In contrast the value of albacore catch increased to its highest level in real terms since 2008–09.
Despite being a managed fishery, the ETBF has previously exhibited some of the economic characteristics of an unmanaged, open-access fishery (Kompas, Che & Gooday 2009). Estimates suggest that the fishery earned negative NER between 2000–01 and 2009–10. Low NER are likely to have been a major reason for a large proportion of the fishery’s permits being inactive. This is a sign that the fishery was overcapitalised. The structural adjustment implemented in 2007 under the Securing our Fishing Future package addressed these issues to a degree—it left fewer vessels sharing a similar amount of catch and revenue.
In March 2011, output controls were introduced for five key target species in the form of TACCs, allocated as ITQs. The removal of some input controls under ITQs can provide fishers with more flexibility to fish with a more efficient combination of inputs (Elliston & Cao 2004). The transferability of statutory fishing rights among fishers also allows more efficient allocation of these rights. This is likely to result in the catch being taken by the most efficient operators in the fishery.
The setting of TACCs in the ETBF is complicated by uncertainty around what level of TACC is consistent with maximising NER from an internationally shared stock (see ‘Performance against economic objective’, below). If TACCs are set too high so that they do not constrain a species’ catch, the incentive for quota trade and the associated positive impacts for fishery-level efficiency are reduced (Elliston et al. 2004). If TACCs are set too low (based on a stock’s biological and economic status), some level of NER will be foregone.
Performance against economic objective
International sharing of stocks complicates both the selection of economic-based targets and the assessment of economic status against the objective of maximum economic yield (MEY), intended to maximise NER to the Australian community. Stock assessment is particularly complicated for the ETBF because the catch may be a relatively small proportion of the total WCPFC catch, and the degree of connectivity between the Australian population and that in the wider region remains uncertain for some species. For some internationally shared stocks, a reduction in the Australian catch may not necessarily lead to response in stock abundance and, therefore, profitability in the long term. For two stocks in the ETBF—swordfish and striped marlin—Australia’s share of the catch is considered to be high enough for domestic action to have a more direct influence on stock abundance. These two stocks are managed under a harvest strategy designed to achieve a catch rate target biomass for prime-size fish consistent with the HSP economic target proxy of 48 per cent of unfished levels. Recent implementation of the harvest strategy indicates that, since 2008, swordfish stock levels have been close to, but just below, the target reference point, although in recent years stock levels have trended away from the target reference point (AFMA 2017). For striped marlin, catch rates have been between the target and limit reference points for more than a decade, but have approached the target since 2013 (Campbell 2016). A movement towards the recommended MEY target supports a movement towards maximising long-run NER in the fishery. However, the potential lack of association between domestic management actions and changes in stock biomass for the tuna species in the ETBF means that stock-wide BMEY may not be relevant.
The species-specific biomass targets in this fishery are based on the expected catch rates and the size proportion that is expected to occur when the level of mean spawners per recruit is at 48 per cent of initial unfished levels. This is assumed to be consistent with the MEY target recommended by the HSP. It is unclear how accurately the target reflects MEY. NER are estimated to have been positive for six of the seven years since the harvest strategy for the fishery was implemented in 2010–11. However, it is unclear to what extent the targets are responsible for this. NER were improving in the fishery before the harvest strategy was implemented, and many factors other than the harvest strategy may have influenced the fishery’s economic performance.
21.4 Environmental status
Product from the ETBF currently has export approval under inclusion on the List of Exempt Native Specimens under the Environment Protection and Biodiversity Act 1999 until 22 August 2019. Conditions under this approval, in addition to standard conditions of reporting and monitoring, include updating the ecological risk assessment for the ETBF, developing and implementing a framework for the management of non-quota and bycatch species, and continuing to determine the impact of fishing in the ETBF on shark species.
Under the level 3 Sustainability Assessment for Fishing Effects (for fish only), two species of sunfish and three species of shark were identified as being at high risk from the effects of fishing in the ETBF (Zhou, Smith & Fuller 2007). A 2012 review of the ecological risk assessment, using new information on sunfish, has reclassified both sunfish species as medium risk. The priorities of the ecological risk management response are to reduce interactions with marine turtles, seabirds and whales because of their protected status (AFMA 2012), and to reduce the capture and mortality of sharks by implementing the 20-shark trip limit. The ecological risk management report also lists specific actions for the priority groups—for example, all vessels in the ETBF are required to carry line cutters and de-hookers so that sharks, turtles and other protected species can be easily removed from fishing gear, should they become hooked or entangled. Results from a new ecological risk assessment in the ETBF in 2018 will be reported in Fishery status reports 2019.
The introduction of electronic monitoring in the ETBF from mid 2015 has improved the accuracy of logbooks, particularly in the reporting of discarded or released catch. This improved reporting may be reflected in apparent higher levels of interaction for 2017, reported below.
In 2017, logbooks indicated that 2,281 shortfin mako sharks (Isurus oxyrinchus)were hooked in the ETBF. Of these, 830 were dead and 1,451 were released in unknown condition. Eighteen longfin mako sharks (I. paucus)were also hooked and released in unknown condition. One hundred and fifty-three porbeagle sharks (Lamna nasus)were hooked and released, with 1 alive, 28 dead and 124 in unknown condition. Three hundred and ninety-five silky sharks (Carcharhinus falciformis) and five grey nurse sharks (Carcharias taurus) were also released in unknown condition. Ninety-five green turtles (Chelonia mydas)were hooked; 77 were released alive, 17 were dead, and 1 was released in unknown condition. Fifty-two leatherback turtles (Dermochelys coriacea) and 26 loggerhead turtles (Caretta caretta)were also hooked; all were released alive except for 1 leatherback turtle in unknown condition and 6 dead loggerhead turtles. Two hawksbill turtles (Eretmochelys imbricata) were hooked, with 1 dead and 1 released alive. Five olive ridley turtles (Lepidochelys olivacea) were caught, with four alive and one dead. Eighteen unidentified turtles were hooked, with 13 alive, 4 dead and 1 in unknown condition.
Three black-browed albatrosses (Thalassarche melanophris)were caught—all dead—and one wandering albatross (Diomedea exulans) was released alive. Thirty-three unidentified albatrosses were hooked, with 10 released alive and 23 dead. Two flesh-footed shearwaters (Ardenna carneipes), 1 sooty shearwater (A. grisea) and 6 unidentified shearwaters were hooked, with all being dead except 1 unidentified shearwater. One unidentified cormorant was released alive.
Several interactions with marine mammals were recorded; these comprised nine unidentified dolphins (released alive), one dead bottlenose dolphin (Tursiops truncatus), six unidentified whales (released alive), one false killer whale (Pseudorca crassidens; released alive), four melon-headed whales (Peponocephala electra; three alive and one dead), two toothed whales (Parvorder Odontoceti; released alive), six short-finned pilot whales (Globicephala macrorhynchus; one alive and five dead), four long-finned pilot whales (G. melas; released alive), one dead dugong (Dugong dugon) and two unidentified seals (released alive).
AFMA 2012, Ecological risk management: report for the Eastern Tuna and Billfish Fishery, Australian Fisheries Management Authority, Canberra.
—— 2017, ‘Tropical Tuna and Billfish Fisheries Resource Assessment Group (TTRAG) meeting 19’, meeting record, 30–31 August 2017, AFMA, Mooloolaba.
Campbell, R 2012, ‘Implementation of the ETBF harvest strategy and calculation of the recommended biological commercial catches for 2013/14’, working paper presented to the fifth meeting of the Tropical Tuna Resource Assessment Group, Canberra, 4–5 September 2012.
—— 2016, ‘Implementation of the ETBF harvest strategy and calculation of recommended biological commercial catches for broadbill swordfish and striped marlin for the 2017/18 quota year’, information paper to the 16th meeting of the Tropical Tuna Resource Assessment Group, Mooloolaba, 18–19 October 2016.
DAFF 2007, Commonwealth Fisheries Harvest Strategy: policy and guidelines, Australian Government Department of Agriculture, Fisheries and Forestry, Canberra.
Davies, N, Hoyle, S & Hampton, J 2012, ‘Stock assessment of striped marlin (Kajikia audax) in the southwest Pacific Ocean’, working paper WCPFC-SC8-2012/SA-WP-05, WCPFC Scientific Committee eighth regular session, Busan, Republic of Korea, 7–15 August 2012.
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