modelling fish populations for sustainability by: james bernard supervisors: charles twardy, david...
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Modelling Fish Populations for Modelling Fish Populations for SustainabilitySustainability
By: By: James BernardJames Bernard
Supervisors: Supervisors: Charles Twardy, Charles Twardy, David Green and David Green and
Charles Todd (From the Department of Sustainability Charles Todd (From the Department of Sustainability and Environment)and Environment)
Murray Cod InformationMurray Cod Information
Murray Cod reside in the Murray RiverMurray Cod reside in the Murray River
Murray Cod that reside in the Murray River Murray Cod that reside in the Murray River are a biological mystery!are a biological mystery!
Murray Cod InformationMurray Cod Information
How the Fish Population Works:How the Fish Population Works:
Eggs
Young Fishling(0 – 4 Years Old)
Mature Fish(5+ Years Old)
Murray Cod InformationMurray Cod Information
How the Fish Population Works:How the Fish Population Works:
Eggs
Young Fishling(0 – 4 Years Old)
Mature Fish(5+ Years Old)
Problems!Problems!
What if the fish are caught before they mature, What if the fish are caught before they mature, and consequently cannot reproduce?and consequently cannot reproduce?– Murray River Rules and Regulations stipulate the Murray River Rules and Regulations stipulate the
Murray cod must be at least 500mm before eligible for Murray cod must be at least 500mm before eligible for fishing.fishing.
– Are they old enough to reproduce at this age?Are they old enough to reproduce at this age?
Problems!Problems!
How can we find out whether they are old How can we find out whether they are old enough to reproduce and contribute any fish enough to reproduce and contribute any fish back to the population?back to the population?
– First step is by producing an Age-Growth CurveFirst step is by producing an Age-Growth Curve
Age-Growth CurveAge-Growth Curve
An example of an Age-Growth Curve for the An example of an Age-Growth Curve for the Murray Cod.Murray Cod.
SnobSnob
A graph produced using SnobA graph produced using Snob
What comes after the Age-Growth curve?What comes after the Age-Growth curve?
More Problems!More Problems!
Age Growth Model
?
Recruitment Process
How many eggs will each mature fish How many eggs will each mature fish produce?produce?– Analyse using different modelsAnalyse using different models– Analyse using aquaculture informationAnalyse using aquaculture information
Recruitment ProcessRecruitment Process
What comes after the Recruitment Process?What comes after the Recruitment Process?
More Problems!More Problems!
Age Growth Model
Population Model
Recruitment Process
Progress …Progress …
A graph produced using MS ExcelA graph produced using MS Excel
(Individual) Fish
Leng
th
YES!YES!– What age do the Murray Cod start producing?What age do the Murray Cod start producing?– What triggers the Murray Cod’s reproduction?What triggers the Murray Cod’s reproduction?– Limited recapture dataLimited recapture data– Inaccurate recapture dataInaccurate recapture data
Potential Problems?Potential Problems?
For further details visit:For further details visit:– http://www.csse.monash.edu.au/~jbernard/Project/http://www.csse.monash.edu.au/~jbernard/Project/
Or contact me at:Or contact me at:– [email protected]@csse.monash.edu.au
Stay Tuned …Stay Tuned …