Eastern Tuna and Billfish Fishery

Chapter 21: Eastern Tuna and Billfish Fishery

J Larcombe, H Patterson and D Mobsby

FIGURE 21.1 Relative fishing intensity in the Eastern Tuna and Billfish Fishery, 2018

TABLE 21.1 Status of the Eastern Tuna and Billfish Fishery
 20172018Comments a
Status
Biological status
Fishing mortality BiomassFishing mortalityBiomass 

Striped marlin (Kajikia audax), south-west Pacific

Not subject to overfishingNot overfishedNot subject to overfishingNot 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

Not subject to overfishingNot overfishedNot subject to overfishingNot 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 overfishingNot overfishedNot subject to overfishingNot overfished

Most recent estimate of spawning biomass (2018) is well above the default limit reference point. Recent estimate of fishing mortality is below FMSY.

Bigeye tuna (Thunnus obesus), western and central Pacific

Not subject to overfishingNot overfishedNot subject to overfishingNot 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 overfishingNot overfishedNot subject to overfishingNot overfished

Most recent estimate of biomass (2017) is highly likely above the limit reference point. Ocean-wide estimates of fishing mortality are highly likely below FMSY.

Economic statusPreliminary estimates suggest NER for the fishery remained positive between 2015–16 and 2017–18. NER improved significantly in 2015–16, rising 40% to $9.1 million, before falling to $4.2 million in 2016–17. The increased NER in 2015–16 were supported by a significant increase in fishing revenue (reflective of the very high yellowfin tuna catch that year). Non-survey-based estimates indicate that NER increased in 2017–18 to $5.1 million because of an increase in estimated fishing revenue more than offsetting estimated higher fishing costs.

a Regional assessments of species and the default limit reference points from the Commonwealth Fisheries Harvest Strategy Policy (Department of Agriculture and Water Resources 2018) are used as the basis for status determination.
Notes:B20 20% of unfished biomass. BMSY Biomass at MSY. FMSY Fishing mortality at MSY. MSY Maximum sustainable yield. NER Net economic returns.

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21.1 Description of the fishery

Area fished

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.

Management methods

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; Department of Agriculture and Water Resources 2018) is not prescribed for fisheries managed under international agreements. However, a harvest strategy framework was developed for the ETBF (Campbell 2012) to set the total allowable commercial catch (TACC) for the five main species. For reasons set out below, this harvest strategy framework has been discontinued for the three tuna species, and is being redeveloped for swordfish (Xiphias gladius) and striped marlin (Kajikia audax).

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. In 2013, the Tropical Tuna and Billfish Fisheries Resource Assessment Group (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). Changes to Australia’s catch of these tuna species 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 domestic harvest strategy, and noting that WCPFC harvest strategies for these species are still under development and there has been no allocation of tuna catches by the WCPFC as yet, AFMA considered a range of other factors in applying TACCs. These include stock status, local catch indices, historical catch levels in the fishery, and limits determined by the WCPFC (through conservation and management measures) or agreed through regional arrangements.

The harvest strategies for swordfish and striped marlin were reviewed in 2017–18, including management strategy evaluation. The review determined that the harvest strategies were not likely to be effective at achieving HSP objectives and so required redevelopment. The AFMA Commission agreed and requested that TTRAG provide the best available scientific indicators to provide catch limit advice while a new harvest strategy is developed.

The status of ETBF tuna and billfish is derived from 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 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 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). The status information in this chapter reflects this change.

Since 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% of video footage of all hauls is reviewed to verify the accuracy of logbooks, which must be completed for 100% of shots.

Fishing effort

The number of active vessels in the fishery (Figure 21.2) has decreased substantially in the past decade (from around 150 in 2002 to 37 in 2016), 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).

FIGURE 21.2 Longline fishing effort, number of boat SFRs and active vessels in the ETBF, 1985–2018

Note: SFR Statutory fishing right.
Source: AFMA

Catch

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 from 4,624 t in 2017 to 4,046 t in 2018 (Figure 21.3). Swordfish and yellowfin tuna continue to be the main target species.

FIGURE 21.3 Total catch (from logbook data) for all methods, by species, in the ETBF, 1987–2018

Source: AFMA

TABLE 21.2 Main features and statistics for the ETBF

Fishery statistics a

20172018

Stock

TACC
(t)

Catch
(t)

GVP (2016–17)

TACC
(t)

Catch
(t)

GVP (2017–18)

Striped marlin

351

288

$1.0 million

311

246

$1.6 million

Swordfish

1,285

1,180

$9.3 million

960

1,027

$9.2 million

Albacore

2,500

992

$4.1 million

2,351

889

$2.7 million

Bigeye tuna

1,056

450

$7.3 million

957

367

$4.3 million

Yellowfin tuna

2,400

1,714

$12.6 million

2,054

1,517

$18.8 million

Total fishery

7,592

4,624

$35.7 million

6,633

4,046

$38.4 million

Fishery-level statistics

Effort

Longline: 8.75 million hooks

Minor line: na

Longline: 7.90 million hooks

Minor line: 0

Fishing permits

Longline boat SFRs: 85

Minor-line boat SFRs: 93

Longline boat SFRs: 82

Minor-line boat SFRs: 84

Active vessels

Longline: 39

Minor line: 2

Longline: 40

Minor line: 0

Observer coverage

Longline: 10.2% b

Minor line: zero

Longline: 10.8% b

Minor line: zero

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; American Samoa, Indonesia, 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.
Notes: ITQ Individual transferable quota. na Not available. SFR Statutory fishing right. TACC Total allowable commercial catch.

21.2 Biological status

Striped marlin (Kajikia audax)

Striped marlin (Kajikia audax)

Line drawing: FAO

Stock structure

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 history

Catch for the ETBF decreased slightly in 2018 to 246 t (Figure 21.4), while catch in the south Pacific decreased from 1,801 t in 2016 to 1,560 in 2017 (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.

FIGURE 21.4 Striped marlin catch and TACC in the ETBF, 1984–2018

Note: TACC Total allowable commercial catch.
Source: AFMA

FIGURE 21.5 Striped marlin catch in the south Pacific, 1970–2017

Source: WCPFC

Stock assessment

The last stock assessment for striped marlin in the SWPO was conducted in 2012 (Davies, Hoyle & Hampton 2012). Significant changes in the base case from the previous (2006) assessment included a 50% reduction in Japanese longline catches over the entire model time period (because catches in the previous assessment were erroneously counted twice), faster growth rates, and the steepness of the stock–recruitment relationship being fixed at a higher level (0.8 rather than 0.55). A decreasing trend in recruitment through time was found, particularly from 1950 to 1970. There were conflicts among the standardised catch-per-unit-effort time series, and a series from the Japanese longline fishery was considered to be the most representative. Estimates of equilibrium maximum sustainable yield (MSY) and the associated reference points were highly sensitive to the assumed values of natural mortality and steepness in the stock–recruitment relationship. Estimates of stock status relative to MSY-based reference points, as used by the WCPFC, are therefore uncertain.

The base case in the assessment estimated that the latest (2010) spawning biomass had been reduced to 34% of the levels predicted to occur in the absence of fishing (SBCURRENT/SBF=0 = 0.34 for the base case; range 0.32–0.44 across the base case and sensitivities). It was estimated that the spawning biomass was below the level associated with MSY (SBCURRENT/SBMSY = 0.87; range 0.67–1.14). Fishing mortality (2007–2010) was below FMSY (FCURRENT/FMSY = 0.81; range 0.51–1.21), and catches during this period were close to the estimated MSY (2,081 t; range 1,914–2,276 t). Annual catches during the most recent five years (2013–2017) have averaged around 2,000 t, around the estimated MSY.

Stock status determination

The most recent estimate of the SWPO spawning biomass of striped marlin is above the limit reference point adopted for tunas (20% of the levels predicted to occur in the absence of fishing; 0.2%SBF=0), noting that the WCPFC has yet to adopt a limit reference point for this stock. The most recent base-case estimates of fishing mortality and most of the sensitivity analyses are below the level associated with MSY, and recent catches are close to 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 2018. 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. An updated assessment is due in 2019.

Yellowfin tuna
Kevin McLoughlin, ABARES

Swordfish (Xiphias gladius)

Swordfish (Xiphias gladius)

Line drawing: Gavin Ryan

Stock structure

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.

Catch history

Swordfish catch in the ETBF decreased slightly in 2018 (Figure 21.6). Catch in the south Pacific has generally been increasing since 2001, but decreased slightly in 2017 to 21,992 t (Figure 21.7).

FIGURE 21.6 Swordfish catch and TACC in the ETBF, 1984–2018

Note: TACC Total allowable commercial catch.
Source: AFMA

FIGURE 21.7 Swordfish catch in the south Pacific, 1970–2017

Source: WCPFC

Stock assessment

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% of the levels predicted to occur in the absence of fishing (SBrecent/SBF=0 = 0.35; 80% 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% of the fishing mortality associated with MSY (Frecent/FMSY = 0.86; 80% probability interval = 0.51–1.23). The probability that the recent fishing mortality was above FMSY was about 32%.

Stock status determination

Based on the uncertainty grid, the spawning biomass is highly likely above the limit reference point of 20%SBF=0 adopted for tunas (noting that the WCPFC Commission has yet to adopt a limit reference point for this stock). 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)

Albacore (Thunnus alalunga)

Line drawing: FAO

Stock structure

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.

Catch history

Catches in the ETBF decreased slightly to 889 t in 2018 (Figure 21.8). Catches in the south Pacific have been stable in recent years, but increased to 93,327 t in 2017 from 68,390 t in 2016 (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.

FIGURE 21.8 Albacore catch and TACC in the ETBF, 1984–2018

Note: TACC Total allowable commercial catch.
Source: AFMA

FIGURE 21.9 Albacore catch in the south Pacific, 1970–2017

Source: WCPFC

Stock assessment

The assessment for albacore in the south Pacific was updated in 2018 using MULTIFAN-CL (Tremblay-Boyer et al. 2018). Significant improvements in the 2018 stock assessment included modifications to the catch rate index of abundance, inclusion of a higher natural mortality (0.4) in the grid, inclusion of alternative growth models and a simplified regional structure. These changes resulted in more optimistic outcomes than the 2015 assessment. The WCPFC Scientific Committee provided advice based on the full set of 72 models in the uncertainty grid, with equal weighting for all axes of uncertainty.

The median recent spawning stock biomass was 52% of the levels predicted to occur in the absence of fishing (SBrecent/SBF=0 = 0.52; 80% probability interval = 0.37–0.63). The probability that the recent spawning stock biomass had breached the limit reference point was zero. The median recent fishing mortality was 20% of the level associated with MSY (Frecent/FMSY = 0.20; 80% probability interval = 0.08–0.41). The probability that the recent fishing mortality was above FMSY was zero.

Stock status determination

The most recent estimate of spawning biomass is very likely above the default limit reference point of 20% of initial unfished levels. The most recent estimates of fishing mortality are very likely 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)

Bigeye tuna (Thunnus obesus)

Line drawing: FAO

Stock structure

Genetic data have indicated that bigeye tuna in the Pacific Ocean is a single biological stock (Grewe & Hampton 1998).

Catch history

Catches of bigeye tuna decreased in the ETBF in 2018, from 450 t in 2017 to 367 t (Figure 21.10), the lowest catch since 1996. Catches increased in the south Pacific in 2017 (Figure 21.11). Recent bigeye tuna catch in the WCPFC area (129,066 t in 2017) is below the estimated MSY (median 158,551 t). Catches have been close to, and occasionally substantially above, this MSY level since around 1997 (Figure 21.11).

FIGURE 21.10 Bigeye tuna catch and TACC in the ETBF, 1984–2018

Note: TACC Total allowable commercial catch.
Source: AFMA

FIGURE 21.11 Bigeye tuna catch in the WCPFC area, 1970–2017

Source: WCPFC

Stock assessment

The bigeye tuna stock in the western and central Pacific Ocean (WCPO) was most recently assessed in 2017 (McKechnie, Pilling & Hampton 2017) using MULTIFAN-CL. The assessment was re-evaluated in 2018, incorporating an updated new growth curve resulting from analysis of an enhanced set of otolith data, but maintaining the other inputs of the 2017 assessment (Vincent, Pilling & Hampton 2018). 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 36 related models after models that used an older and inaccurate bigeye growth curve were removed. The updated assessment of biomass and fishing mortality status is more optimistic (as a result of the inclusion of the new growth curve, new regional structures and increased recruitment), and uncertainty is lower than in the 2017 assessment, primarily due to removal of old growth models within the grid.

The median recent spawning biomass was 36% of the levels predicted to occur in the absence of fishing (SBrecent/SBF=0 = 0.36; 80% probability interval = 0.30–0.41). There was a zero probability that the recent spawning stock biomass had breached the limit reference point. The median recent fishing mortality was 77% of the level associated with MSY (Frecent/FMSY = 0.77; 80% probability interval = 0.67–0.93). There was a roughly 6% probability that the recent fishing mortality was above FMSY.

Stock status determination

Based on the uncertainty grid, the spawning biomass is very likely to be above the limit reference point of 0.2%SBF=0 adopted for tunas. As a result, the stock is classified as not overfished.Similarly, recent fishing mortality is very likely to be below FMSY. As a result, the stock is classified as not subject to overfishing.

Yellowfin tuna (Thunnus albacares)

Yellowfin tuna (Thunnus albacares)

Line drawing: FAO

Stock structure

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 history

Catch decreased slightly in the ETBF in 2018 to 1,516 t (Figure 21.12). In the south Pacific, the 2017 catch was a record high of 681,391 t (Figure 21.13), which is above the estimated MSY (median 670,800 t).

FIGURE 21.12 Yellowfin tuna catch and TACC in the ETBF, 1984–2018

Note: TACC Total allowable commercial catch.
Source: AFMA

FIGURE 21.13 Yellowfin tuna catch in the WCPFC area, 1970–2017

Source: WCPFC

Stock assessment

The yellowfin tuna stock in the WCPO was most recently assessed in 2017 (Tremblay-Boyer et al. 2017) using 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% of the levels predicted to occur in the absence of fishing (SBrecent/SBF=0 = 0.33; 80% probability interval = 0.20–0.41). The probability that the recent spawning stock biomass had breached the limit reference point was about 8%. The median recent fishing mortality was 74% (Frecent/FMSY = 0.74; 80% probability interval = 0.62–0.97). The probability that the recent fishing mortality was above FMSY was about 4%.

Stock status determination

Based on the uncertainty grid, the spawning biomass is very likely to be above the limit reference point of 0.2%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

Gross value of production in the ETBF increased by 8% in 2017–18 to $38.4 million (Figure 21.14). The increase in production value was the result of an increase in the value of yellowfin tuna catch more than offsetting significant declines in the value of albacore and bigeye tuna catch. The value of yellowfin tuna catch increased by 49% in 2017–18 to $18.8 million. This was due to a 60% increase in catch (to 1,858 t) more than offsetting a 7% decline in average price. In 2017–18, yellowfin tuna remained the most valuable species caught in the ETBF, followed by broadbill swordfish ($9.2 million).

In 2017–18, bigeye tuna achieved the highest average price of the five quota species (increasing 6% to around $11.5 per kilogram), so the decline in the value of bigeye tuna catch was the result of a 44% decline in landed catch (on a financial year basis). The increased price for bigeye tuna is largely attributed to strong import demand from the United States (which overtook Japan in 2016–17 to be the key export destination of Australian bigeye tuna).

FIGURE 21.14 Real GVP for the ETBF, 2007–08 to 2017–18

Note: GVP Gross value of production.

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 (Figure 21.15). Preliminary survey results for the ETBF are available for the 2015–16 and 2016–17 financial years. Non-survey-based estimates for economic performance are available for the 2017–18 financial year.

In 2015–16, NER for the ETBF are estimated to have increased to $9.4 million—the highest net return to the fishery in real terms since economic surveys of the ETBF began. This was supported by an estimated 32% increase in fishing revenue (largely reflective of the very high yellowfin tuna catch that year), favourable prices (as indicated by an improvement in fishers’ terms of trade) and increased productivity (as indicated by an increase in total factor productivity). NER declined in 2016–17, but remained positive at $4.2 million. This was largely the result of a decline in fishing income more than offsetting lower operating costs.

Preliminary non-survey-based estimates of NER for 2017–18 show an increase to $5.1 million, largely as a result of a 10% increase in fishing income.

FIGURE 21.15 NER for the ETBF, 2007–08 to 2017–18

Notes: NER Net economic returns. Data for 2015–16 to 2017–18 are preliminary.
Source: Mobsby forthcoming

Management arrangements

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 fishing season in the ETBF has been March to February, but it was shortened in 2018 and ran from March to December. This was done as a transition to new season dates that will start in January and end in December of each year, with the first calendar year season beginning in 2019.

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) from the fishery (consistent with the HSP), which are intended to maximise NER to the Australian community. For the ETBF, 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 most key commercial species. For these internationally shared stocks, a reduction in the Australian catch may not necessarily lead to an appropriate response in stock abundance and, therefore, profitability in the long term. In 2013, it was determined that 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. In 2017–18, the harvest strategies for swordfish and striped marlin were reviewed, finding that the harvest strategies were not likely to be effective in achieving the objectives of the HSP (see ‘Management methods’). Without an economic-based target for catch (that is, one associated with the fishery-level MEY objective), the level of catch in the fishery cannot be assessed against MEY.

NER are estimated to have been positive for seven of the eight years since the harvest strategy for the fishery was implemented in 2010–11. 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. For example, fishers’ terms of trade (the prices paid for inputs relative to prices achieved for outputs) for the ETBF have been generally favourable for the period 2010–11 to 2016–17.

21.4 Environmental status

Product from the ETBF currently has export approval from inclusion on the List of Exempt Native Specimens under the Environment Protection and Biodiversity Conservation 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.

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 2018, reported below.

In 2018, logbooks indicated that 1,980 shortfin mako sharks (Isurus oxyrinchus) were hooked in the ETBF. Of these, 1 was alive, 670 were dead and 1,309 were released in unknown condition. Nine longfin mako sharks (I.paucus) were also hooked, with three dead and six released in unknown condition. Six porbeagle sharks (Lamna nasus) were hooked, with two dead and four in unknown condition. One hundred and thirty silky sharks (Carcharhinus falciformis) were also released in unknown condition, while one whale shark (Rhincodon typus) was released alive. Thirty-six green turtles (Chelonia mydas) were hooked; 27 were released alive and 9 were dead. Sixty-eight leatherback turtles (Dermochelys coriacea) were hooked, with 63 released alive, 4 dead and 1 in an unknown condition. Similarly, 18 loggerhead turtles (Carettacaretta) were hooked; all were released alive except for one turtle in unknown condition and three dead. Five hawksbill turtles (Eretmochelys imbricata) were hooked, with one dead and four released alive. Seven olive ridley turtles (Lepidochelys olivacea) were caught, with all released alive. Twenty-two unidentified turtles were hooked, with 16 alive and 6 dead.

Four black-browed albatrosses (Thalassarche melanophris) were caught—three dead and one alive—and six wandering albatross (Diomedea exulans), with two alive and four dead. Fifty-six unidentified albatrosses were hooked, with 15 released alive and 41 dead. One sooty shearwater (Ardenna grisea), 1 short-tailed shearwater (Puffinus tenuirostris) and 17 unidentified shearwaters were hooked, with all being dead except 3 unidentified shearwater. Four Australian gannet (Morus serrator) were hooked and dead, as were three unidentified birds.

A number of interactions with marine mammals were recorded; these comprised four unidentified dolphins (three released alive), one dead bottlenose dolphin (Tursiops truncatus), seven short-finned pilot whales (Globicephala macrorhynchus; five alive and two dead), one long-finned pilot whale (G. melas; released alive), one humpback whale (Megaptera novaeangliae; released alive) and five unidentified seals (released alive).

21.5 References

AFMA 2012, Ecological risk management: report for the Eastern Tuna and Billfish Fishery, Australian Fisheries Management Authority, Canberra.

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.

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, Western and Central Pacific Fisheries Commission Scientific Committee eighth regular session, Busan, Republic of Korea, 7–15 August 2012.

––, Pilling, G, Harley, S & Hampton, J 2013, ‘Stock assessment of swordfish (Xiphias gladius) in the southwest Pacific Ocean’, working paper WCPFC-SC9-2013/SA-WP-05, WCPFC Scientific Committee ninth regular session, Pohnpei, Federated States of Micronesia, 6–14 August 2013.

Department of Agriculture and Water Resources 2018, Commonwealth Fisheries Harvest Strategy Policy, Department of Agriculture and Water Resources, Canberra.

Elliston, L & Cao, L 2004, Managing effort creep in Australian fisheries: an economic perspective, Australian Bureau of Agricultural and Resource Economics eReport 04.5, prepared for the Fisheries Resources Research Fund, Canberra.

——, Newton, P, Galeano, D, Gooday, P, Kompas, T & Newby, J 2004, Economic efficiency in the South East Trawl Fishery, ABARE report prepared for the Fisheries Resources Research Fund, Canberra.

Farley, J, Clear, N, Kolody, D, Krusic-Golub, K, Eveson, P & Young, J 2016, ‘Determination of swordfish growth and maturity relevant to the southwest Pacific stock’, working paper WCPFC-SC12-2016/SA-WP-11, WCPFC Scientific Committee 12th regular session, Bali, Indonesia, 3–11 August 2016.

Grewe, PM & Hampton, J 1998, ‘An assessment of bigeye (Thunnus obesus) population structure in the Pacific Ocean based on mitochondrial DNA and DNA microsatellite analysis’, SOEST 98-05, JIMAR contribution 98-320, Joint Institute for Marine and Atmospheric Research, University of Hawaii, Honolulu.

——, Feutry, P, Hill, PL, Gunasekera, RM, Schaefer, KM, Itano, DG, Fuller, DW, Foster, SD & Davies, CR 2015, ‘Evidence of discrete yellowfin tuna (Thunnus albacares) populations demands rethink of management for this globally important resource’, Scientific Reports, vol. 5, doi 10.1038/srep16916.

Kasapidis, P, Magoulas, A, García-Cortés, B & Mejuto, J 2008, ‘Stock structure of swordfish (Xiphias gladius) in the Pacific Ocean using microsatellite DNA markers’, working paper WCPFC-SC4-2008/BI-WP-04, WCPFC Scientific Committee fourth regular session, Port Moresby, Papua New Guinea, 11–22 August 2008.

Langley, A, Herrera, M & Million, J 2012, ‘Stock assessment of yellowfin tuna in the Indian Ocean using MULTIFAN-CL’, paper IOTC-2012-WTT14-38_Rev 1, Indian Ocean Tuna Commission 14th session of the Working Party on Tropical Tunas, Mauritius, 24–29 October 2012.

McDowell, JR & Graves, JE 2008, ‘Population structure of striped marlin (Kajikia audax) in the Pacific Ocean based on analysis of microsatellite and mitochondrial DNA’, Canadian Journal of Fisheries and Aquatic Sciences, vol. 68, pp. 1307–20.

McKechnie, S, Pilling, G & Hampton, J 2017, ‘Stock assessment of bigeye tuna in the western and central Pacific Ocean’, working paper WCPFC-SC13-2017/SA-WP-05, WCPFC Scientific Committee 13th regular session, Rarotonga, Cook Islands, 9–17 August 2017.

Mobsby, D forthcoming, Australian fisheries economic indicators report 2018:financial and economic performance of the Eastern Tuna and Billfish Fishery, ABARES, Canberra.

Purcell, CM & Edmands, S 2011, ‘Resolving the genetic structure of striped marlin, Kajikia audax, in the Pacific Ocean through spatial and temporal sampling of adult and immature fish’, Canadian Journal of Fisheries and Aquatic Sciences, vol. 65, pp. 1861–75.

Takeuchi, Y, Pilling, G & Hampton, J 2017, ‘Stock assessment of swordfish (Xiphias gladius) in the southwest Pacific Ocean’, working paper WCPFC-SC13-2017/SA-WP-013, WCPFC Scientific Committee 13th regular session, Rarotonga, Cook Islands, 9–17 August 2017.

Tremblay-Boyer, L, McKechnie, S, Pilling, G & Hampton, J 2017, ‘Stock assessment of yellowfin tuna in the western and central Pacific Ocean’, working paper WCPFC-SC13-2017/SA-WP-06, WCPFC Scientific Committee 13th regular session, Rarotonga, Cook Islands, 9–17 August 2017.

——, Hampton, J, McKechnie, S & Pilling, G 2018, ‘Stock assessment of South Pacific albacore tuna’, working paper WCPFC-SC14-2018/SA-WP-05, WCPFC Scientific Committee 14th regular session, Busan, Republic of Korea, 8–16 August 2018.

Vieira, S, Perks, C, Mazur, K, Curtotti, R & Li, M 2010, Impact of the structural adjustment package on the profitability of Commonwealth fisheries, ABARE research report 10.01, ABARE, Canberra.

Vincent, MT, Pilling, G & Hampton, J 2018, ‘Incorporation of updated growth information within the 2017 WCPO bigeye stock assessment grid, and examination of the sensitivity of estimates to alternative model spatial structures’, working paper WCPFC-SC14-2018/SA-WP-03, WCPFC Scientific Committee 14th regular session, Busan, Republic of Korea, 8–16 August 2018.

WCPFC 2013, Commission for the Conservation and Management of Highly Migratory Fish Stocks in the Western and Central Pacific Ocean: Scientific Committee ninth regular session—summary report, Pohnpei, Federated States of Micronesia, 6–14 August 2013, WCPFC, Pohnpei.

—— 2015, Commission for the Conservation and Management of Highly Migratory Fish Stocks in the Western and Central Pacific Ocean: Scientific Committee 11th regular session—summary report, Pohnpei, Federated States of Micronesia, 5–13 August 2015, WCPFC, Pohnpei.

Zhou, S, Smith, T & Fuller, M 2007, Rapid quantitative risk assessment for fish species in selected Commonwealth fisheries, report to AFMA, CSIRO, Australia.





Last reviewed: 4 November 2019
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