FITZROY RIVER BARRAMUNDI REVIEW 2016

There were a total of 10 forecasts made for Barramundi in size of fish, catch rates, trends in stocks and recruitment. Taggers catch rates do not reflect the catch rates of the total fishing population however as taggers are generally in the top 20% of fishers that catch most fish their catches are more sensitive to changes in fish stocks and are comparable from year to year. Forecasts are available at www.crystal-bowl.com.au.

Season 2016 forecasts versus actual

Taggers

  • Of the forecasts for taggers 6 (60%) were within the forecast range and 3 within 10% of the forecast range
  • Strong recruitment in 2013 and no commercial netting have contributed to the increased catch rate of legal fish
  • Forecast of poor recruitment was accurate and reflected the El Niño conditions that existed over the recruitment period (Jan-May)
  • Recruitment was also late in the recruitment period with no recruits recorded until late Mar (usually recorded in Jan) and recruit survival likely to be low
  • There was a reduction in the stock level reflected in the drop in the number of tags - poor recruitment resulted in little or no contribution to the stock while fishing mortality was reduced due to no commercial netting and increased slightly for recreational fishing
  • The slight reduction in the overall catch rate reflected the reduction in stock level

Rocky Barra Bounty

  • This year’s fishing conditions were the worst for lure fishing in the 17 years of the Bounty with a flush of very dirty water just before the event making fishing conditions and accurate forecasts much more difficult
  • The boundaries of the event were extended this year because of the conditions however the results have been confined to the previous maps FRR, RAG and CIS to make them comparable with previous years
  • The Barramundi average size of 646mm and the catch rate for legal fish of 0.6 fish/tagger/day were the highest in the 17 years of the Bounty and the catch rate was 74.9% higher than in 2015
  • The low number of Barramundi recruits recorded (4.4% under 400mm) supports earlier recruitment surveys resulting in 2016 being a very poor recruitment year

Environmental conditions

  • El Niño conditions persisted through to May and were neutral through to Oct
  • There were 3 periods of river flows resulting in minor flooding in Feb-Mar, Jul-Aug and a fresh flow in Oct
  • The minor flooding in Jul-Aug resulted in a significant reduction in fishing effort due to turbid water and low water temperatures
  • 12 Mile benchmark site had a small fish kill of around 20 Barra in early Feb due to low rainfall and poor conditions but conditions improved after rainfall in Feb
Infofish Australia
January 2017
MEASURE FORECAST

ACTUAL

GRAPH

FITZROY 2016

2016

Fish sizes
Undersize fish 200-579mm
Legal - trophy fish 580-999mm
Trophy fish >1m


70% (60-80%)
25% (15-35%)
5% (0-15%)

Taggers/Bounty
75.9%  31.8%
17.9%  68.2%
1.1%  0.0%

click to enlarge
Percentage of fish in size ranges

Highest  Lowest
LEGAL-TROPHY
2015    2009
73.0    2.5

TROPHY
2016    2010
11.2    0.0

click to enlarge

Actual catch rates taggers and Bounty

Fish/tagger/day

Taggers/Bounty

Overall
2.6-3.3    0.3-0.4
Legal fish
0.5-0.6    0.1

Taggers/Bounty

Overall
2.7    0.6
Legal fish
0.7    0.5

click to enlarge
Catch rates percentage change compared with 2015

Taggers/Bounty

Overall
+0-20    -160-180
Legal fish
+10-30    -160-180

Taggers/Bounty

Overall
-4.7%    -31.6%
Legal fish
+40.3%    +74.9%

click to enlarge
Barramundi tags in river indicator of trends in stockMost likely and range  Tagged fish 2016 (Jan-Dec)
1,800-2,200
-5-+15% compared with 2015
Tagged fish 2016 (Jan-Dec)
1,191
-15% compared with 2015
click to enlarge
RecruitmentRecruits/fisher/day Poor<0.5 Poor

0.27

click to enlarge
12 Mile recruitment benchmark site
0-100 recruits
Risk of fish kill if rainfall low to Oct 2016
19 recorded
Minor fish kill in Feb 2016
click to enlarge
Rocky Barra Bounty Barramundi caught and average size 150 (100-200) caught 249 (+66%) caught 
646mm average size
click to enlarge
Commercial catchGrids R29 and R30
Catch tonnes
Catch rate kg/day
None forecast as river is now a net free zone Catch
2015
85.61t
Catch rate
93.3kg/day
click to enlarge
River flow and Barramundi 2016 Poor recruitment and low fishing effort after July flooding
click to enlarge
River flow and Barramundi 2007-2016
click to enlarge

DATA SOURCES

Data used in the Fitzroy Barramundi Crystal Bowl are:  

BASIS FOR ANALYSES

The analyses of the data were based on the following:
  • Effort data for taggers were the number of days fished in the tidal reaches of map areas FRR, Rag and CIS where King Threadfin and/or Barramundi were caught
  • Catch rates for taggers was calculated as fish/fisher/day
  • Catch rates for commercial fishers was calculated as kg/day
  • Stock trends were based on a modeled estimate of the number of tags in the river each year where the tag reduction rate was calculated based on the reduction of recaptures each year
  • The most likely number of tags was based on a tag reduction rate of 0.5 each year up to 2015 and 0.6 for 2016 taking into account no commercial catch
  • Recruits were based on tracking recruits over the first year from Jan-Oct with fish in Jan-Feb 0-250mm, Mar-Apr 0-300mm, May-Aug 0-350mm, Sep-Oct 0-400mm
  • In 2016 recruits only reached 300-350mm by Sep-Oct