Australian Rivers Institute Griffith University Effect of climate change on estuarine fish production in Queensl, Australia J.-O. Meynecke
Study location
Study objectives Is there a relationship between fish catch climate parameters how strong is it? What are the differences between regions species? Can the relationship be used for modelling? What are the consequences for fisheries management?
Rainfall in Australia Queensl 7379 mm 1 mm Average annual rainfall in Australia
Temperature in Australia Queensl
Rainfall temperature projections 2030 2050 2070
fisheries Food security, economic loss Habitat change Fish exploitation policies Fish assemblages & abundance Direction of change Industrial strategies Fishing pressure Economic consequences Biological response Stress, spawning, movements Change in food supply Sea level Wind speed & direction Currents Ocean temperature Atmospheric temperature influenced abiotic factors CO 2 Light Salinity, oxygen, DOC Precipitation & runoff
Selection of species King Tiger Prawns Barramundi Mud Crab Mullet
Selection of rainfall regions
Selection of stations Weather stations 50 km buffer zone 500 kilometres
Fish record grid system
fish catch data Data on catch, effort (number of days boats) gross value of production for fish species from 1988-2004 were provided by DPI&F Annual monthly temperature data were provided as point data rainfall data as average values for 8 coastal regions for the time period 1988-2004 were obtained from BOM
Tools Relationships between catch, temperature rainfall (monthly, seasonal annual) were explored using single linear regression models correlation analysis Catch, effort rainfall data were entered into the CLIMPROD program to generate a simple surplus production model
Barramundi catch - rainfall 250 500 Total catch Catch in t Rainfall Rainfall in mm 0 1 205 month 0
Monthly barramundi catch - rainfall.153**.108**.148**.450**.435**.240**.213**.214**
Seasonal mud crab catch - rainfall.720**.630*.630*.620*.800**
Annual tiger prawn catch - rainfall.630*.510*.530*
Annual mullet catch - rainfall.780**
CLIMPROD model Species r 2 MSY in t (+ SE) Barramundi 0.93 246 East coast a; c (±40) Mullet a; c 0.75 2076 (±101) Mud Crab b; c 0.87 221 (±63) King Prawn b; c 0.41 3176 (±281) Tiger Prawn b; c 0.61 2464 (±313) CPUE model Modification av b exp(ecv d ) Age at recruit. 4yr a + bv + cv 2 + de Age at recruit. 3yr a + bv + ce Exploited year classes 3 (a + be) (1/c-1) Exploited year classes 3 (a + bv) exp(ce) Age at recruit. 1yr
Annual barramundi catch - temperature.833**.470*
Monthly mud crab catch temperature.310**.440**.580**
Monthly tiger prawn catch - temperature -.230** -.460** -.250** -.610**.510**
Annual mullet catch - temperature.870**.550*.660*
- temperature Monthly yearly average temperatures were related to prawn, mud crab, barramundi mullet catch for which higher monthly air temperature resulted in higher catch rates in south-east Queensl Shift from positive temperature effects towards a negative relationship for the northern regions Limited temperature data for a number of stations significant differences between air water temperature analyses are therefore somehow compromised
- rainfall Regional differences in the rainfall catch relationship were significant Wetter periods between May August may stimulate the migration of mullet higher river flow stimulates the downstream movement of mud crabs Lagged effect of river flow on barramundi catches due to enhanced productivity increased survival /or growth of the juvenile stages -> positive effects of rainfall (e.g., availability of food) or negative effects (e.g., higher mortality)
Investigating relationships between mud crabs rainfall for a number of states in Australia Incorporation into bioeconomic models Identify a more comprehensive management policy that will ensure sustainability even under conditions of higher environmental pressure, e.g., a reduction of rainfall
Acknowledgment I like to thank the Department for Primary Industries Fisheries the Bureau of Meteorology for providing fish climate data Michael Arthur, Joe Lee, Norm Duke, Jan Warnken, Leonard Olyott,, Karen Danaher, Julie Robins for ideas, support comments during this project
There are temperature threshold limits for crustacean zoea megalopa larval stages. Staples Heales (1991) found the lowest survival rates of juvenile P. merguiensis at high temperature (30 C) low salinity (< 10 ppt).