SPF Scientific Panel draft advice November 2017

The Small Pelagic Fishery (SPF) Scientific Panel met on 16/17 November in Melbourne. The key items for discussion were:

  • Jack Mackerel daily egg production method survey results
  • Annual assessment of SPF stocks to inform 2018-19 TAC setting process
  • Proposed new fishing methods in the SPF (jigging and line methods)
  • Research Priorities for 2019-2020 and DEPM schedule
  • Review Scope for Ongoing Monitoring Requirements in the SPF
  • Spatial Management in the SPF

The Panel’s draft recommendations / advice on these items is provided in italics below each item. Further information on each of these items will be presented at the Stakeholder Forum meeting.

Jack Mackerel West Daily Egg Production Method survey results

A daily egg production method (DEPM) survey was undertaken in January 2017 for the western Jack Mackerel stock. This is the first time a DEPM survey has been undertaken for this stock. DEPM surveys underpin the SPF Harvest Strategy which is used to set the annual total allowable catches for the fishery.

  • The DEPM survey area commenced at Kangaroo Island and continued east towards south west Tasmania. No sampling was undertaken west of Kangaroo Island.
  • Two major areas of spawning activity were identified, the southern side of Kangaroo Island and north of King Island to western Victoria – either side of the Bonney Coast.
  • The Panel noted that additional data collected outside of the structured survey suggested a large amount of spawning activity in western Bass Strait.
  • Considering the high concentration of spawning activity in eastern Bass Strait that was identified during the 2014 jack mackerel east survey, one hypothesis is that the eastern area of the western zone may be part of the eastern zone stock.
  • The spawning activity of the western stock may commence around Kangaroo Island – with the Bonney upwelling possibly providing a natural barrier between the stocks.
  • While the results of the DEPM do not provide conclusive evidence of a stock split, the Panel recommended that any future jack mackerel DEPM should be designed to take the location of spawning through Bass Strait into account.
  • The Panel noted that only a limited number of adult samples were able to be collected during the jack mackerel west survey and therefore the adult parameters obtained from the 2014 eastern jack mackerel survey were used to input into the biomass calculation for the western stock.
  • The Panel considered two biomass estimates from the DEPM survey, one derived only from the structured survey (25 182 tonnes) and one derived from all sampling including the additional sampling undertaken in Bass Strait (34 978 tonnes).
  • The Panel agreed that the biomass estimate to be used for the recommended biological catch (RBC) should be 34 978 tonnes. The Panel considered that this was conservative given that the stock extends west of Kangaroo Island and a large amount of spawning activity was detected in Bass Strait which was not extensively sampled (and therefore the biomass estimate is an underestimate).
  • Considering the limited information on jack mackerel to the west of Kangaroo Island and the spatial separation of the two key spawning areas found during the survey (Kangaroo Island and western Bass Strait – either side of the Bonney upwelling) which may be evidence of a stock boundary, the Panel recommended that as an interim measure until more is known about the biomass and / or stock structure of jack mackerel west, that catch taken directly south of Kangaroo Island should be restricted to 20 per cent of the RBC. This percentage is equivalent to the proportion of spawning activity found during the DEPM survey in this area.

Annual assessment of SPF stocks to inform 2018-19 TAC setting process

Monitoring and a fishery assessment is undertaken annually for each of the SPF stocks. The SPF Harvest Strategy applies harvest control rules to the available biomass estimates from DEPM surveys to determine a RBC for each SPF quota species. Other sources of mortality are then applied to the RBCs to derive the total allowable catch (TAC) recommendations by AFMA Management.

Table 1: Draft Panel Advice on the annual assessment and 2018-19 recommended biological catches for SPF stocks

Jack mackerel east The DEPM and associated adult sampling provided robust estimates of key parameters. Results published in March 2015 with a best estimate of biomass of 157 805 tonnes.

The annual assessment provided no basis to change the Panel’s previous advice for this species.   The Panel agreed that the DEPM survey results were appropriate for setting jack mackerel RBCs under the Harvest Strategy for the 2018-19 season.

Fourth season at Tier 1

 

RBC: 18 937 tonnes (157 805 x 12%)

Jack mackerel west A DEPM survey for jack mackerel was conducted in 2017 which provided a best estimate of biomass of 34 978 tonnes.

On the basis of the information provided, the Panel agreed that the DEPM survey results were appropriate for setting jack mackerel RBCs under the Harvest Strategy for the 2018-19 season.

First season at   Tier 1

 

RBC: 4 197 tonnes

(34 978 x 12%)

Blue mackerel east The annual assessment provided no basis to change the Panel’s previous advice for this species.  The Panel confirmed that while there is uncertainty associated with the adult parameters used in the DEPM, the DEPM survey biomass estimate of 83 300 tonnes is appropriate to be used as the basis for providing RBC advice.

The current exploitation rate of 15 per cent is considered to be precautionary (as shown by the MSE testing by Smith et al 2015) and accounts for uncertainties in the assessment.

Third season at Tier 1

 

RBC: 12 495 tonnes

(83 300 x 15%)

Blue mackerel west The Panel noted that the most recent DEPM survey for this stock had been undertaken in February and March 2005. The annual assessment provided no basis to change the Panel’s previous advice for this species.  The Panel confirmed its previous support of the SPFRAG approach which adopted a biomass estimate for blue mackerel of 86 500 tonnes based on the results of the two surveys that covered most of the western spawning area. Second season at Tier 3

 

RBC: 3 243 tonnes

(86 500 x 3.75%)

 

Australian sardine east The annual assessment provided no basis to change the Panel’s previous advice for this species. The Panel confirmed its previous recommendation to use the biomass estimate from the northern survey to recommend a RBC for the northern area and that only the NSW State catches should be taken off the RBC when setting the TAC.

This recommendation was based on recent research (Izzo et al. 2017, Ward et al. in prep, and Sexton et al. submitted to Fisheries Oceanography) that provides indications of stock structuring, with a north stock and south eastern stock (with the stock spilt occurring around the NSW/Victorian border).

Third season at  Tier 1

 

RBC: 9 915 tonnes (49 575 x 20%)

Redbait east The Panel noted the most recent biomass estimates from DEPMs in October 2005 and October 2006 of 86 990 tonnes and 50 782 tonnes, respectively. The annual assessment provided no basis to change the Panel’s previous advice for this species. The Panel confirmed that the approach used by SPFRAG of adopting the average of these DEPM estimates (68 886 tonnes) should be continued, and the Harvest Strategy Tier 2 harvest rate for redbait of 5 per cent be used as the basis for RBC advice. Seventh season at Tier 2

 

RBC: 3 444 tonnes (68 886 x 5%)

Redbait west There has been no DEPM survey for this stock and therefore this species remains a Tier 3 stock. It was noted that a DEPM survey is currently underway for this stock which will be available for the 2019-20 TAC setting process.

Using the mean biomass estimate of 66 000 tonnes from Atlantis, the proposed Tier 3 exploitation for this stock with no DEPM is: 0.25 x 5 % (Tier 2 rate) = 1.25 %.

Second season at Tier 3

 

RBC: 825 tonnes (66 000 x 1.25%)

2019-20 Research Priorities

As part of the AFMA annual research cycle requires, MACs and RAGs are required to review the relevant fishery five year strategic research plans to identify the annual research needs. The process to develop the 2019-20 research priorities for the SPF has commenced with advice from the Panel which will be considered by the South East Management Advisory Committee in 2018 before consideration by the AFMA Research Committee.

  • The Panel agreed to retain the annual monitoring and assessment of the fishery as a priority for 2019-20, which is currently funded until 2018-19.
  • The Panel agreed to maintain the current order of DEPM surveys (Blue mackerel west then Redbait east) but whether these proceed as planned in 2018-19 and 2019-20 respectively will be subject to fishing effort.
  • The Panel noted the support from the Commonwealth Marine Mammal Working Group for the marine mammal research priority in the SPF and supported its inclusion in the 2019-20 research plan.
  • The Panel agreed on an additional research priority for 2019-20 to utilise the information collected from the previous and upcoming South Australian Sardine survey to better understand the relevant SPF stocks west of Kangaroo Island for which there is currently limited information.
  • The Panel agreed that the Fisheries Research and Development Corporation jack mackerel genetic research scope should be removed from the 2019-20 research plan as the Panel did not see the project as a current priority for the fishery.

Review Scope for Ongoing Monitoring Requirements in the SPF

With the commencement of a new mid-water trawl vessel in the SPF, a review of the available information and data will be undertaken to inform the ongoing monitoring requirements within the SPF.

  • The Panel endorsed the project scope proposed to review the available observer and electronic monitoring data to provide advice on the ongoing data and monitoring requirements for the fishery.
  • Regarding the data needs for bycatch, given the low proportion of bycatch in this fishery the Panel considered that the priority for the monitoring regime under the current level of fishing effort is to be able to provide data on species composition only.

Proposed new fishing methods in the SPF

AFMA has received an application and enquiries on the use of jigging and line methods in the SPF. While these are not currently permitted methods, there is a provision within the SPF Management Plan that allows AFMA to determine additional permitted methods in the fishery.

The Panel supported the proposal for the use of jigging and line methods in the SPF on the basis that:

  • the fishery is largely undeveloped
  • these methods do not pose any risk to the ecological sustainability of the target species, as catches will be within the TAC
  • both methods are more selective and pose a lower risk to bycatch and protected species interactions than the currently permitted methods. The Panel identified seabirds as the most likely species group to interact with either method but noted that effective mitigation options are available if an issue is identified.

The Panel recommended that observer coverage for the initial five trips would be adequate to get an indication of any potential bycatch species, including protected species.

Spatial Management in the SPF

Spatial management, in the form of regional catch limits, were introduced in 2015 for mid-water trawling in the SPF to distribute effort across the fishery and collect representative data on target species that may also feed into future integrated stock assessments. Although the risk of localised depletion occurring in the SPF is considered to be low, regional catch limits may further reduce the risk by restricting catches in localised areas of the fishery over time. AFMA is seeking advice from the Panel regarding the need for spatial management arrangements in the SPF.

The Panel confirmed its previous advice that the risk of localised depletion in the SPF is low, especially considering the current level of effort in the fishery. The most appropriate way to ensure the sustainability of target species is to set conservative catch limits which is achieved through the SPF Harvest Strategy. Further, in terms of spreading effort to support the collection of representative data on target species, the benefit of regional catch limits is minimal as this type of data collection is best achieved through research surveys, given the characteristics of the fishery.

On this basis, any ongoing justification for spatial management relates to the issue of localised depletion. In this context and in light of the experience in the fishery over the last two seasons, it was considered whether there was still a need for the spatial management provisions that currently apply.  In summary the Panel concluded:

  • the requirement that only 75 per cent of an individual’s quota holdings can be taken in a single sub-area in a fishing year should be removed as any risk of localised depletion is best managed on a smaller scale
  • the current trigger of 2 000 tonnes (all species combined) within a rolling 30 day period as the limit at which vessel/s must move out of that grid, should be replaced by a 10 per cent of TAC trigger as a percentage (rather than a fixed tonnage), this better reflects the most recent science on stock sizes.

The Panel also considered that from time to time specific spatial management provisions that differ from the above general approach, might need to be adopted to address specific circumstances.