FITZROY RIVER BARRAMUNDI FORECAST SEASON 2018

There is a total of 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 will be reviewed in Jan 2018 before the season opens when there will be more certainty about recruitment. Forecasts are available at www.crystal-bowl.com.au.

Season 2018 forecasts

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 moderate with neutral to slightly La Niña conditions during the recruitment period (Jan-Apr) but highly uncertain due to the following:
  • River flows in Oct 2017 may reduce salinity on the spawning ground and affect spawning success, at least during the early part of the spawning period (Oct-Dec)
  • The increase in spawning stock due to no commercial netting could result in recruitment higher than forecast
  • 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

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
  • Rainfall and river flows in late Dec-early Feb will be critical to recruitment success however river flows in Oct 2017 may affect early spawning

Infofish Australia
November 2017

MEASURE FORECAST

ACTUAL

GRAPH

FITZROY 2018

2018

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

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

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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) 1,500 (1,200-1,800)
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Recruitment Recruits/fisher/day Moderate 1.5 (1.0-2.0)
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12 Mile recruitment benchmark site Moderate 250 (200-300)
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Climate outlook to Jun 2018 Neutral Weak La Niña Nov 2017-Jan 2018
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Rainfall outlook Dec 2017-Feb 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: