National recreational fishing survey of Southern Bluefin Tuna

The Commonwealth has contracted the University of Tasmania to undertake a survey of recreational fisher effort, catch, release and harvest estimates of Southern Bluefin Tuna (SBT) and other large tuna and billfish.

The survey will be undertaken in South Australia (SA), Victoria (VIC), Tasmania (TAS) and New South Wales (NSW) using varied techniques appropriate to each state as described below. The survey methodology is based on the 2015 report ‘Developing robust and cost-effective methods for estimating the national recreational catch of Southern Bluefin Tuna in Australia’ (Moore et al., 2015).  Data collection will begin on 1 December 2018 and conclude on 30 November 2019. The survey results are expected to be available by mid-2020.

Western Australia is not being surveyed by the University of Tasmania because the data on SBT catch in Western Australia is collected bi-annually by the Western Australian Department of Primary Industries and Regional Development. The Western Australian data will be included in the analysis and final report of the national SBT recreational fishing survey. SBT are not found off the Queensland or Northern Territory coasts.

Methodology

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Tasmania

A multi-faceted survey approach will be used to estimate recreational catch and effort for SBT and other large tuna and billfish species in TAS. 

Key components include:

  • an offsite phone-diary survey of gamefish fishing activity undertaken from private vessels;
  • a limited access-point survey to verify species identification and provide size composition data (to enable conversion of numbers to weight); and
  • gamefish tournament monitoring to supplement catch and size composition data. 

Charter boat catches will be assessed using the compulsory logbook administered by the TAS Department of Primary Industries, Parks, Water and Environment, and a voluntary logbook for charter operators not required to complete the compulsory logbook.

Private fishing boat sector

A phone diary survey (PDS) will be employed to collect data from recreational fishers accessing the fishery from private vessels and will be based on the methodology successfully developed and applied by the Institute for Marine and Antarctic Studies in a previous survey of offshore fishing in TAS (Tracey et al., 2013).

The recreational vessel registry administered by Marine and Safety Tasmania will provide the sample frame for this component, with the vessel representing the primary sampling unit. The database will be stratified based on the residence of the vessel owner (using Australian Bureau of Statistics regional strata) and vessel size. A stratified random sample will be drawn from the database, with higher sample fractions for vessel size classes demonstrated to be suitable for offshore game fishing.

A screening survey will be implemented to establish whether each vessel had been used for game fishing in the previous 12 months and the likelihood it would be used for game fishing during the enumeration period (December 2018 – November 2019). Eligible respondents will be invited to participate in the diary survey with all game fishing activity conducted from the vessel monitored in detail using the PDS method.

This method will utilise true probabilistic sampling and weighting proportional to the ‘population’ of registered private vessels. Information recorded will include the trip date, fishing location, target species, fishing method, effort (fishing duration), number of fishers and catch by species (retained and released numbers). At the conclusion of the diary period, a ‘wash-up survey’ will be undertaken.

Non-intending fisher (vessel) follow-up, with a subsample of non-diary eligible vessel owners, will be conducted at the end of the diary period to provide an assessment of ‘unexpected’ game fishing vessel usage. 

The PDS methodology will deliver state-wide and regional estimates of the catch (numbers), effort and harvest of tuna and billfish for the private fishing boat sector. The survey method  conforms to the methodologies outlined in Moore et al. (2015). Proposed sample sizes are outlined in Table 1.

Table 1 – Proposed target sample numbers and relative sample fractions. Sample fractions are derived on the assumption that the target vessel population (~15,000) is similar to that reported by Tracey et. al. (2013).
PDS survey componentTarget sample sizePredicted sample fraction
Screening interviews2,100~14% of vessels considered suitable for game fishing
Eligible respondents for diary survey~400~19% of screened vessels
Non-intending fisher interview~350~21% of non-intending fishers reported at screening
Wash-up interview~400

A validation study of the size (length and weight) of SBT will be conducted at geographically stratified boat ramps throughout the survey period, to corroborate size measurements that will be collected from some participants during the offsite phone diary survey. Major game fishing tournaments will also be monitored onsite by project staff as part of the size validation study.

Charter boat sector

Catch and effort from the charter boat sector will be collected using a combination of compulsory and voluntary logbooks, administered to members of the charter sector in TAS that catch, or are likely to catch, tuna or billfish species.

Victoria

A probability-based intercept survey (creel survey), conducted at key access points in southwest VIC identified in previous studies (Green et al., 2012), will be applied to assess the catch, effort and release rates of SBT caught by the recreational sector in the state. These will include the primary location of Portland, which has an additional access point (boat ramp) since the survey conducted by Green et al., 2012, as well as Port Fairy, Warrnambool and Apollo Bay. 

The creel surveys will begin on 1 December 2018 and conclude on 30 November 2019. Contact details of access-point interview respondents will be collected to generate a frame from which a sample can be derived, to perform the wash-up survey administered as part of the offsite survey in the other target states.

Access point survey

The sampling frequency at each site will be weighted according to whether they are high, medium or low frequency access points, as identified by Green et. al. (2012). A ‘day’ will be used as the primary sampling unit (PSU), which will be stratified to either a weekday or weekend/public holiday, with a higher sampling frequency assigned to weekend/public holidays (see Table 2).

A seasonal stratification will also be applied, using the maximum sampling fractions (Table 2) during peak seasons and a reduced sampling fraction in seasons where there is a reduced probability of fishers encountering SBT. Survey days at each location will be selected by random stratified sampling, based on the strata outlined above. Sampling events will occur for daytime fishing only.

Table 2. Proposed sampling fraction at each location for weekday and weekend/public holiday strata.
SiteMaximum sampling fraction weekdaysMaximum sampling fraction weekend/public holidays
Portland0.350.7
Port Fairy0.250.5
Warrnambool0.20.4
Apollo Bay0.20.4

On each sampling day, a crew member of each vessel retrieved at the boat ramp will be interviewed and asked a series of questions related to the fishing activity that occurred from the vessel on the day. Questions will include core information relating to the capture of SBT and other game fish species, such as fishing location, effort (fishing time), number of fishers, number of target species caught (kept and released). SBT will be measured on a random selection process throughout the onsite survey.

If the number of vessels returning to the boat ramp at a given time exceeds the capacity of the creel clerks to interview all vessels, the clerks will randomly interview as many as possible, and record the number of vessels missed.

Given that this onsite access point survey is being conducted in western VIC, which is the focal point of the SBT recreational fishery in the state, it is expected that data on other game fish species will be limited. Fishers are highly unlikely to encounter billfish in western VIC. Similarly the only target tuna species, other than SBT, regularly encountered in southwest VIC are Albacore. Data on this species will be collected routinely during the onsite access point survey.

Charter boat fishery

A voluntary charter boat logbook system will be used to collect catch, effort and release rate information for SBT caught by the charter boat sector. To maximise reporting rates, an incentive scheme will be implemented over the peak charter season for SBT, from March to July.

The incentive will be a monthly fuel voucher for each vessel where all log sheets are completed for a given month. To be eligible for the fuel voucher incentive, charter captains will need to register their intent to participate in the scheme prior to the peak season. This and the logbook requirements will be clearly outlined to them.

In addition, the regional survey manager will contact all charter boat operators on a regular basis (~weekly) during the peak season to encourage them to complete the log sheets. This will occur face-to-face at boat ramps, as well as by telephone as required. By identifying charter trips in the access point survey, the possibility of double counting will be eliminated.

The logbooks will be as simple as possible to minimise respondent burden, with data elements to include:

  1. Date of trip
  2. Departure location
  3. Effort (hours fished)
  4. Number of clients
  5. Target species
  6. Number of SBT caught, retained and released
  7. Approximate fishing location.

Game fishing competition monitoring

No Victorian-based game fishing competitions that target SBT were identified by Moore et. al. 2015.  However, since publication of that report, a fishing competition run in conjunction with the ‘Hooked on Tuna Festival’ has been established at Portland, which runs over four weekends through April.

Given the high sampling fraction for the onsite survey being conducted at Portland, it is likely that most fish landed as part of this competition will be recorded. However, access to the data collected directly by the competition organisers to further supplement fish size data will be endeavoured.

New South Wales

The method for data collection in NSW will be a large sample phone recall survey, specific to catch and effort of game fishing activity for SBT and other large tuna and billfish species by individuals with a NSW recreational fishing licence. Charter boat catches will be assessed using the compulsory logbook administered by NSW DPI. Collation of data from an existing gamefish tournament monitoring program will provide information on tournament catches and fish size composition data. 

These survey components will provide demographic and participation information for licensed recreational fishers in NSW, as well as robust information on the catch, effort and release rates of SBT and partial data on the catch, effort and release rates of other tuna and billfish species caught by fishers with a recreational fishing licence in NSW.

Given the ‘season’ length for targeting SBT in NSW is significantly shorter than in the southern states of Australia and the large size of the recreational fishing licence database, a large recall survey method will be used to generate robust estimates of catch and effort for the target species, rather than a longitudinal PDS.

In NSW the fish are accessed over a much shorter period (typically 1-2 months), a longitudinal study is not considered necessary and would significantly inflate the cost of determining a robust catch estimate of SBT. Therefore a brief interview with a random sample of recreational licence-holders, will be conducted soon after the SBT run off NSW. The timing of these interviews will be informed by tracking social media and other reports of SBT featuring in catches. An effective recall period of about 4-8 weeks for a memorable activity, such as fishing for SBT, is not expected to result in a significant recall bias.

Once the season has been identified as effectively complete, approximately 7.5% of the licensed population (~30k) will be contacted and use a survey questionnaire similar to that administered in the screening phase of the PDS conducted in other states. The focus of the recall survey will be to identify fishers who have fished for SBT and, if they have, they will also be asked about their catch of other tuna and billfish species.

A stratified random sample will be drawn from the database, with higher sample fractions (Table 3) for respondents from statistical divisions along the south coast of NSW, Sydney and Canberra. This method will utilise true probabilistic sampling and weighting proportional to the ‘population’ of licenced recreational fishers in NSW.  At the conclusion of the survey period on 30 November 2019, respondents identified as catching or targeting SBT during the recall survey will be contacted again and asked whether they caught additional SBT since their recall interview. This will confirm that the recall survey captured the whole SBT season in NSW or, alternatively, that additional catch is recorded. During this call the wash-up survey will also be conducted.

Table 3. Proposed target sample numbers and relative sample fraction for a one-off recall survey in NSW –sample fraction is derived on the assumption the population of licensed recreational fishers in NSW is ~400,000
Survey componentsTarget sample sizePredicted sample fraction
Recall interviews30,000~10% of people holding a NSW recreational fishing licence
Wash-up interview~300

Game tournament monitoring

The NSW Gamefish Tournament Monitoring Program is an ongoing program and will run in 2019/2020. During this time, targeted information will be collected on large tuna, including SBT and billfish. Some targeted sampling will focus on tournaments conducted within the southern coast of NSW (Ulladulla and Bermagui) to effectively cover representative areas of the target species’ range in NSW.

The Gamefish Tournament Monitoring Program will provide data on the numbers of anglers and catch at regular intervals during tournament fishing days. The program will utilise radio schedules and post-fishing interviews to collect data. Onsite monitoring at game tournaments where SBT are likely to be landed will occur to measure the size of any SBT landed.

Charter boat sector

A mandatory charter logbook system is in place in NSW. Logbook records from the period of this study will be examined to provide a record of the number of target species caught by the charter boat sector. A limited charter boat observer program will occur, to provide additional data on the size of SBT caught in NSW.

South Australia

A probability-based intercept survey (creel), conducted at key access points in SA, will be applied to assess the catch, effort and release rates of SBT and other tuna and billfish caught by the recreational sector in the state. Given the large number of access points in SA, the methodology applied will be based on that conducted by Moore et. al. (2015), but with a higher number of sampling days as recommended by Moore et. al. (2015) to improve confidence intervals around harvest and effort estimates.

The state will be stratified into regions, with random sampling of access points conducted in each regional stratum. The access points (boat ramps) targeted will be based on those reported by Moore et. al. (2015) and confirmed by a series of experts, to ensure any shifts in the dynamic of boat ramp use since the last survey was conducted are incorporated. 

Further stratification for day type will also be implemented, with weekdays sampled at a lower sampling fraction than weekend/public holidays. A seasonal stratification will also be applied, with the maximum sampling fractions applied during peak seasons and a reduced sampling fraction applied in seasons where there is a reduced probability of fishers encountering SBT. Sampling events will occur for daytime fishing only.

The actual sampling fractions for each region and access point will be determined after confirmation by expert interviews on the ramps currently most commonly used by game fishers. Based on the recommendations arising from Moore et. al. (2015), a total of 550 sample days is expected, which includes sampling at Port MacDonnell.

Port MacDonnell will be treated separately, as it is the most commonly used access point to target SBT for the recreational sector in SA. An access point survey will be conducted at this location, replicating the methods proposed for the onsite surveys in VIC, using ‘day’ as the PSU and a similar sampling fraction to that proposed for the Portland boat ramp in VIC.

The creel surveys will begin on 1 December 2018 and conclude on 30 November 2019. The contact details of access-point interview respondents will be collected, to generate a frame from which a sample can be derived to perform the wash-up survey, administered as part of the offsite survey in the other target states.

On each sampling day, a member of each vessel retrieved at the boat ramp will be interviewed and asked a series of questions related to the fishing activity that occurred from the vessel on the day. Questions will include core information relating to the capture of SBT and other game fish species including other large tuna and billfish, such as fishing location, effort (fishing time), number of fishers and number of target species caught (kept and released). SBT will be measured based on a random selection process throughout the onsite survey.

If the number of vessels returning to the boat ramp at a given time exceeds the capacity of the creel clerks to interview all vessels, the clerks will randomly interview as many as possible, and record the number of vessels missed.

Charter boat sector

Catch and effort from the charter boat sector will be collated from the mandatory charter boat logbook program which operates in SA.

References

GREEN, C., BROWN, P., GIRI, K., BELL, J. & CONRON, S. 2012. Quantifying the recreational catch of southern bluefin tuna off the Victorian coast. Department of Primary Industries, Victoria.

MOORE, A., HALL, K., KHAGESWOR, G., TRACEY, S., HANSEN, S., STOBUTZKI, I., WARD, P., ANDREWS, J., NICOL, S. & BROWN, P. 2015. Developing robust and cost-effective methods for estimating the national recreational catch of Southern Bluefin Tuna in Australia. Canberra: Australian Bureau of Agricultural and Resource Economics and Sciences.

TRACEY, S., LYLE, J., EWING, G., HARTMANN, K. & MAPLESTON, A. 2013. Offshore recreational fishing in Tasmania 2011/12. Hobart, Tasmania: Institute for Marine and Antarctic Studies.

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