FITZROY RIVER BARRAMUNDI FORECAST SEASON 2018

Preliminary forecasts were made for the 2018 Barramundi season at the end of the 2017 season in Nov and the forecasts are now updated for the start of the season. There are 10 forecasts made for Barramundi in size of fish, catch rates, trends in stocks and recruitment. Catch details are based on fishers that are the top 20% of fishers (T20) that catch 80% of the fish. Their catch rates do not reflect the catch rates of the total fishing population however 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 2018 forecasts

Overall outlook

Stocks to continue to decline while the catch rate for legal fish to remain strong at 1.0-1.4 fish/fisher/day however recruitment will be poor/moderate for the 3rd year in row.

T20 Fishers

  • Legal size fish will make up the greatest proportion of the catch (55-75%) with a slight increase in trophy size fish (0-15%)
  • Catch rate overall to remain steady or increase slightly (1.8-2.2 fish/fisher/day) and will also remain steady for legal fish (1.0-1.4 fish/fisher/day)
  • Stock level to decline with natural and fishing mortality exceeding recruitment in in 2016 and 2017 and likely to be the same in 2018

Recruitment

Forecast for recruitment is poor/moderate with slightly La Niña conditions during the recruitment period (Jan-Apr) but highly uncertain due to the following:
  • Environmental conditions were uncertain for spawning from Oct-Dec 2017 due to possible reduced salinity from a river flow (0.18GL) in Oct 2017
  • The increase in spawning stock due to no commercial netting could result in recruitment higher than forecast
  • Recruitment is enhanced by high river flows in Jan- early Feb and the conditions and climate outlook suggest the conditions will result in poor/moderate recruitment
  • The high population of legal fish may lead to cannibalism of recruits if conditions don't allow recruits early access to nursey areas to reduce predation
  • Initial recruitment surveys in Jan indicate a low level of recruitment with low numbers of recruits recorded from the river and 12 Mile Creek (benchmark site)

Environmental conditions

  • Neutral to slightly La Niña conditions are forecast for the recruitment period (Jan-Apr) with an average wet season with neutral conditions for the remainder of the year
  • Forecast for Fitzroy catchment is a 50-60% chance of exceeding median rainfall from Feb-Apr and rainfall to date suggests that conditions may not be conducive to recruitment

Infofish Australia
January 2018

MEASURE FORECAST

ACTUAL

GRAPH

FITZROY 2018

2018

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


5% (0-15%)
65% (55-75%)
30% (20-40%)

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Actual catch rates taggers
Fish/fisher/day

Fish/tagger/day

T20 Fishers

Overall
2.0 (1.8-2.2)
Legal fish
1.2 (1.0-1.4)

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Catch rates percentage change compared with 2017

T20 Fishers

Overall
10% (0-+20%)
Legal fish
0% (-10-+10%)

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Barramundi tags in river indicator of trends in stock
Most likely and range
Tagged fish 2018 (Jan-Dec)
1,000 (8000-1,200)
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Recruitment
Recruits/fisher/day
Poor/Moderate
1.0 (1.0-2.0)
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12 Mile recruitment benchmark site Moderate
150 (100-200)
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Climate outlook to Jun 2018
Neutral
Weak La Niña
Jan-Apr 2018
Neutral
May-Oct 2018
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Rainfall outlook
Feb 2018-Apr 2018
BOM forecast
45-55% chance of exceeding median rainfall
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DATA SOURCES

Data used in the Fitzroy Barramundi Crystal Bowl are: