Seasonal closure and minimum legal size for barramundi in the Gulf ...

While the significance of this to male spawning rates cannot be determined, the
results of the model suggest that amending the size limit to 58 cm may be of
relatively low risk as long as there is reliable annual recruitment. Again, it is also
worth noting that after a recent review of fish size limits for the east coast fishery,
barramundi minimum legal size limit remained at 58 cm.
Length of the Gulf seasonal closure
The seasonal closure has an overall benefit to a wide range of fish species, not just
barramundi. This benefit includes constraining the overall level of effort exerted in the
commercial net fishery by a third compared to allowing net fishing throughout the
year. It also has a benefit in protecting other species during spawning, including
sharks that undergo pupping in the warmer period.
While it is not possible to quantify this benefit, it is likely to make a significant
contribution to the overall sustainability of Gulf fisheries resources. It is therefore
unlikely that any significant reduction in the length of the current closure would be
supported by any stakeholders in the fishery.
Results of the analysis show that there would be a decrease in barramundi yield from
aligning with the east coast’s three-month closure. Such results also make it difficult
to justify reducing the closure by any significant amount, as this would possibly have
both economic and biologically adverse impacts.
Timing of the Gulf seasonal closure
Apart from any interest in aligning the Gulf closure to the east coast closure, the
primary aim of any change to the variable closure would be to avoid overlapping with
the spring school holiday period. Moving to a fixed date may also have secondary
benefits in aiding planning within the commercial fishery, as well as in improving
overall compliance by moving to a simpler and more certain regime. Any change to
the seasonal closure therefore requires a balance between the social and economic
impacts of the type of closure (i.e. fixed or variable) with the need to ensure that the
biological requirements of the species are being adequately met.
If it is decided through the review that there are significant benefits to having fixed
opening and closing dates for the seasonal closure, then a decision will also need to
be made on what those dates should be. As there is no biological criteria that could
be used for setting those dates, any proposal should be determined initially on the
basis of social and economic impacts. These proposed dates should then be
checked against the biological requirements of the species to ascertain whether they
are likely to cause a significant impact on barramundi stock status. If there is believed
to be any significant risk then measures to mitigate such risks may also be
considered.
In regards to setting a date to end the seasonal closure, it would be logical to
consider aligning with the east coast closure, which ends on 1 February. This would
have the following potential benefits:
minimal impact on Gulf barramundi stocks, as the latest the season is currently
scheduled to reopen is 4 February (in 2017)
greater simplicity and consistency and thus possible benefits for compliance
Technical report prepared for the Gulf finfish review. Not government policy. 7