THE AWOONGA BARRAMUNDI STORY 1985-‐2014

 THE AWOONGA BARRAMUNDI STORY 1985-­‐2014 THE AWOONGA BARRAMUNDI STORY 1985-­‐2014 REPORT This report has been prepared by Infofish Australia for the Australian National Sportfishing Association Qld Inc – March 2015 SCOPE This report provides a summary of tagging of Barramundi stocked in Lake Awoonga near Gladstone, with a focus on the period from 2010-­‐2015 when the lake spilled each year with stocked fish exiting the lake. DATA SOURCE Tagging and recapture records from 1985-­‐2014 are maintained in the Suntag database at http://qld.info-­‐fish.net. Access to the database is limited to authorised users. Data on stocking was provided by the Gladstone Area Water Board. Data on Boyne River flows from www.dnrm.qld.gov.au/water/water-­‐monitoring-­‐and-­‐
data/portal for Station 133005A to June 2012. Tag grid maps and Google Earth maps are available at www.suntag.org.au. LOCATION Lake Awoonga is located 30km south of Gladstone and is covered by Suntag grid map GLA. Figure 1: Suntag grid map of Lake Awoonga 2
SUMMARY OF LAKE AWOONGA 2002-­‐2014 A brief summary of Lake Awoonga1 ! The dam wall was raised to 40m AHD in 2002 ! The lake did not spill from 2002-­‐Dec 2010 ! The lake reached it lowest level of 20.84m in Feb 2003 ! The lake reached it second lowest level of 29.11m in Feb 2008 ! The lake reached its highest level of 48.30m in Jan 2013 ! The lake spilled from Dec 2010-­‐Jun 2011 for the first time since the dam wall was raised in 2002 ! The lake spilled again in Jan-­‐Feb 2012 ! The lake spilled again from Jan-­‐Jun 2013 and reached its recorded highest level ! The lake just overtopped the spillway in Mar 2014 ! The lake spilled again in Jan-­‐Mar 2015 (currently) SOME OBSERVATIONS Some observations for stocked Barramundi in Lake Awoonga 1985-­‐2014: ! From 1996-­‐2013 there were 3,868,432 Barramundi stocked in Lake Awoonga with 988,550 stocked from 2010-­‐2014 ! From 1985-­‐2014 there were 14,776 Barramundi tagged in Lake Awoonga with 14,037 tagged by GAWB as fingerlings (150-­‐250mm) ! It was estimated that 30,000+ Barramundi (GAWB estimate was 20,000) spilled from the lake from Dec-­‐ 2010-­‐Jun 2011 ! Fish that spilled were in 2 size ranges from 400-­‐600mm and 800-­‐1,200mm ! Approximately 1,200 fish perished, mainly due to physical damage during the early stages of the spill ! Following the 2011 spill there were 1,740 Barramundi tagged in the area from below the dam to Manns Weir ! Fish tagged in Lake Awoonga and below the dam were mostly recaptured in the Gladstone area ! One fish was recaptured 760km to the north in the Ross River and another was recaptured 270km to the south in the Burrum River ! Most fish that moved outside the area moved to the south with 4 recaptured in the Burnett River, 1 in the Kolan River and 1 in the Burrum River ! More fish spilled from the lake in 2012, 2013 and 2015 however no estimate of numbers was made ! Growth in the lake after 1 year was around 320mm, after 2 years was around 468mm and after 5 years was around 784mm. ! Based on growth a fish stocked in the lake at 216mm would reach 1m in length 5 years after release. 1
From GAWB website http://www.gawb.qld.gov.au/dam-­‐levels 3
FISH STOCKED INTO LAKE AWOONGA Fish have been stocked into Lake Awoonga since the 1980s. The Gladstone Area Water Board (GAWB) established a fish hatchery in the 1990s and has stocked the lake since then. Table 1 shows the numbers of fish stocked from 1996-­‐Jun 2013.2 Table 2 shows the numbers of Barramundi stocked from 2010-­‐2015.3 Species Numbers stocked Av size Barramundi 3,868, 432 40.6mm Sea Mullet 526,718 52.8mm Yellowfin Bream 78,003 No record Mangrove Jack 70,942 70.9mm Silver Perch 100,625 No record Golden Perch 105,825 No record Sooty Grunter 25,500 No record Sleepy Cod 2,000 No record Southern Saratoga 72 No record Pikey Bream 14 No record Barred Javelin 4 No record Total 4,778,135 Table 1: Fish stocked into Lake Awoonga by GAWB from 1996-­‐2013 Barramundi Numbers stocked 2010-­‐11 207,000 2011-­‐12 344,000 2012-­‐13 220,550 2013-­‐14 198,000 2014-­‐15 315,500 (350 tagged) Total 2,271,600 Table 2: Barramundi stocked into Lake Awoonga by GAWB from 2010-­‐2015 FISH SPILLING FROM LAKE AWOONGA The dam wall was raised in 2002 to 40m AHD. In Dec 2010 the lake spilled for the first time since the wall was raised. The dam spilled from Dec 2010-­‐Jun 2011 and it was estimated by GAWB that 20,000 Barramundi spilled from the lake. In 2011 the Gladstone commercial catch was 249.0t and that was up 1,600% on 2010. The average length of fish in the 2011 catch was 927mm and 9.15kg in weight. That equates to 27,700 fish and when 1,204 tagged fish (average length 790mm), an unknown recreational catch and unknown fish not caught is added it suggests the number of fish that spilled from Awoonga was likely to be higher than the GAWB estimate. Approximately 1,200 fish perished, mainly due to physical damage during the initial stages of the spill. There were 2 size ranges of fish in the spill with fish from 400-­‐600mm and 800-­‐1,200mm. Figure 2 shows 3 Barramundi at the top of the Awoonga spillway in 2011. 2
3
From GAWB website http://www.gawb.qld.gov.au/fish-­‐hatchery From GAWB Hatchery 4
The dam spilled again from Jan-­‐Feb 2012, Jan-­‐Jun 2013, a minor spill in Mar 2014 and again from Jan 2015. Fish spilled from the lake in 2012, 2013 and 2015 and were mostly in the size range 500-­‐600mm. There were no estimates of the numbers of fish that spilled. The spilled of stocked fish from impoundments is not limited to Lake Awoonga or Barramundi. Barramundi and Bass leave most impoundments where they are stocked when the dam spills eg Barramundi from Lake Monduran and Bass from Lake Somerset. Barramund
i Barramund
Barramund
Figure 2: Barramundi at the top of the Awoonga spillway in 2011 TAGGED BARRAMUNDI From 1985-­‐2015 there were 14,776 Barramundi tagged in Lake Awoonga with 14,037 tagged by GAWB as fingerlings (150-­‐250mm). Of those 13,553 were tagged from 1995-­‐2000. There were more fingerlings tagged from 2005-­‐2010 however the records were lost. Over the same period there were 6,372 Barramundi tagged in the Gladstone area in Suntag grid maps BRG, GLD, CR02 and CISG with 4,691 tagged from 2010-­‐2015. Figure 3 shows the tagging each 5 years. The tagging in 2010-­‐2015 accounts for 73.6% of the tagging effort over the past 30 years. This increase is largely due to fish spilling from Lake Awoonga and then being tagged, mostly In the area below the dam to Manns Weir downstream, a distance of about 5km. This is a freshwater section of the river. In the 25 years prior to 2010 there were only 30 Barramundi tagged in that section for the river. From 2010-­‐2015 there have been 1,740 fish tagged being mostly fish that spilled from Lake Awoonga. 5
Figure 4 shows the locations where tagged fish were released or fish were tagged in the lake and in the area downstream to Manns Weir. Figure 3: Barramundi tagged in Lake Awoonga and in the Gladstone area from 1985-­‐2015 Figure 4: Fish tagged in Lake Awoonga and below the dam to Manns Weir Figure 5 shows the timeline of Barramundi tagged in the Boyne River from below the dam from 1985-­‐2015. This shows the low numbers of fish from 1985-­‐2010 and then the fish that spilled from Lake Awoonga. It shows the 2 size classes of fish that spilled 6
from the lake in 2011 being 400-­‐600mm and 800-­‐1200mm. Figure 6 shows the same timeline for the Calliope River that also shows an influx of fish similar to the ones that spilled from Awoonga not long after they spilled. This indicates that the fish that spilled from the lake moved throughout the Gladstone area and into the Calliope River. Figure 5: Timeline of Barramundi tagged in the Boyne River below Lake Awoonga 1985-­‐2015 Figure 6: Timeline of Barramundi tagged in the Calliope River 1985-­‐2015 BARRAMUNDI RECAPTURES From 1985-­‐2010 there were 14,773 Barramundi tagged in Lake Awoonga with 229 (1.6%) recaptures. All except 1 fish were recaptured in the lake. That fish was a tagged fish released into the lake in Jan 1996 and recaptured in Jun 1997 in the Boyne River after going over the dam wall. 7
Following the spilling of the lake in 2011 a further 49 (0.3%) fish were recaptured with all being recaptured outside the lake. Of those 4 were recaptured twice. While most fish were recaptured in the Gladstone area there were 2 fish recaptured in the Burnett River 180km south and 1 fish recaptured in the Fitzroy River 100km north. Figure 7: Locations where Barramundi tagged in Lake Awoonga were recaptured Figure 8: Locations where Barramundi tagged in Lake Awoonga were recaptured in the Gladstone area 8
Figure 9: Recaptures of Barramundi tagged below Awoonga dam wall to Manns Weir Figure 10: Recaptures in the Gladstone area of Barramundi tagged below Awoonga dam wall to Manns Weir 9
From 2010-­‐2015 there were 1,740 fish tagged below the dam wall to Manns Weir with 244 (14.0%) recaptured with 20 recaptured twice, 2 recaptured 3 times and one recaptured 4 times. Of those 157 (64.3%) were recaptured in the area from the dam wall to Manns Weir. The remaining fish were recaptured as far away as 760km north in the Ross River at Townsville and 270km south in the Burrum River at Hervey Bay. There were also 4 fish recaptured in the Burnett River and 1 fish in the Kolan River. Figure 7 shows where fish tagged in Lake Awoonga were recaptured and figure 8 shows where they were recaptured in the Gladstone area. Figure 9 shows where fish tagged below the dam wall to Manns Weir were recaptured and figure 10 shows where they were recaptured in the Gladstone area. BARRAMUNDI GROWTH There were 198 recaptures where growth was assessed. This was for fish tagged from 150-­‐
300mm when stocked and recaptured in the lake. Growth was assessed for fish that were out for 90 days or more and had positive growth. Figure 11 shows the growth of fish compared with days out between tagging and recapture. Growth after 1 year was around 320mm, after 2 years was around 468mm and after 5 years was around 784mm. Based on that growth a fish stocked at 216mm would reach 1m in length 5 years after release. Figure 11: Growth of Barramundi in Lake Awoonga
10