department of primary industry, fisheries and mines drowning or waving? understanding the...
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DEPARTMENT OFPRIMARY INDUSTRY, FISHERIES AND MINES
Drowning or Waving? Understanding the Difference, and Coping with Changes in Fisheries
Rik Buckworth, Fisheries Research
www.nt.gov.au/dpifm
Come Rain, Come Shine: Sustainable Development and the Challenges of the 21st C
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DEPARTMENT OFPRIMARY INDUSTRY, FISHERIES AND MINES
Overview
• Fisheries and Fisheries Research – who we are, what we do
• Drivers of Change - Change is the real issue
• Examples of what we CAN do about it
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DEPARTMENT OFPRIMARY INDUSTRY, FISHERIES AND MINES
We Are Here Because Fishing Feeds PEOPLE
• Production of food, food security
• Economic value – jobs
• “Nourishment for the soul” – recreational and non-catch values
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DEPARTMENT OFPRIMARY INDUSTRY, FISHERIES AND MINES
Fisheries Research Provides Information for Management of Fisheries
Fisheries ManagementFisheries Research
Society Government
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DEPARTMENT OFPRIMARY INDUSTRY, FISHERIES AND MINES
Things WILL Change . . . Drivers
• Climate, other environmental drivers– Warming oceans, sea level change, circulation change,
acidification, changes to river flows, nutrient loadings• Socio-economics – local
– Prosperity – “clean and green”, land use, Australians are moving north!
– Population growth, especially coastal indigenous communities• Socio-economics– global
– Prosperity in China and India – “clean and green”– Fuels? Carbon emission constraints
• Technological – people will get better at catching fish• Catastrophe – a wild card
– Avian flu (what would people do without chook?!), Pilchard die off• Everything interacts!
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DEPARTMENT OFPRIMARY INDUSTRY, FISHERIES AND MINES
Technological Change is not Always This Obvious
What we aspired to in the 1980s!
Standard barra boat now!
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DEPARTMENT OFPRIMARY INDUSTRY, FISHERIES AND MINES
Global Ecological Limits to Fishing
• Fisheries already take most of the potential harvest from productive coastal waters
• Overfishing in some areas puts pressure on the rest of the world - thus illegal foreign fishing in N Australia waters
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DEPARTMENT OFPRIMARY INDUSTRY, FISHERIES AND MINES
Change will happen . . .What to do?
• What are likely changes and potential responses - not all change will be predictable
• Enhance ability to detect change – the biggest problem in fisheries science
• Adaptively manage risks – develop resilient systems
• Northern Australia is in a unique position to do it well!
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DEPARTMENT OFPRIMARY INDUSTRY, FISHERIES AND MINES
Detecting changes in fished populations
• Changes in abundance – all measures have cost/ benefit tradeoffs:– Surveys (trawl, gillnet, aerial) - $$$– Tagging to estimate abundance - $$ – Changes in age structure - $$– Changes in species composition (logs and
observer) -$– Catch rates - CHEAP – so it is the ‘standard’ way
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DEPARTMENT OFPRIMARY INDUSTRY, FISHERIES AND MINES
Catch rate changes in shark and grey mackerel
• Are there more sharks and mackerel? Changing target species? Improved technology?
• All of the above!
0
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1983 1985 1987 1989 1991 1993 1995 1997 1999 2001 2003 2005
Year
CP
UE
(kg
/day
)
CPUE shark
CPUE blacktip
CPUE-grey mackerel
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DEPARTMENT OFPRIMARY INDUSTRY, FISHERIES AND MINES
A Simple Harvest Rule for Guiding a Fishery
Catch the optimum proportion of the fish stock*
Experience shows that this approach is resilient
How . . . ?
Tagging is the most direct way
*Optimum Catch = Optimum Harvest Rate X Abundance
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DEPARTMENT OFPRIMARY INDUSTRY, FISHERIES AND MINES
Tagging is a good way to measure harvest rates in sharks . . .
• They are tough animals, suitable tags are durable and visible• Small cooperative industry -1540 tagged in current project• … but tricky to handle
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DEPARTMENT OFPRIMARY INDUSTRY, FISHERIES AND MINES
Three Challenges in Using Tagging to Measure Harvest Rates
• Tagging can change behaviour, expose fish to mortality – not all fish are as robust as sharks
• Tags simply fall out • People do not report tags (what %?)
• Expensive experimentation can overcome these problems ??
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DEPARTMENT OFPRIMARY INDUSTRY, FISHERIES AND MINES
What about fish that are not as tough when handled? There has to be another way!!
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DEPARTMENT OFPRIMARY INDUSTRY, FISHERIES AND MINES
What we are Doing with Spanish Mackerel . . .
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DEPARTMENT OFPRIMARY INDUSTRY, FISHERIES AND MINES
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DEPARTMENT OFPRIMARY INDUSTRY, FISHERIES AND MINES
A device for collecting tissue was needed . . .
. . . so we invented one!
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DEPARTMENT OFPRIMARY INDUSTRY, FISHERIES AND MINES
Genetag process
“Tagging”
“Recapture” Screen fins
DNA f/print
Matches
Get tissue
Harvest rates
DNA f/print
mixing
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DEPARTMENT OFPRIMARY INDUSTRY, FISHERIES AND MINES
Genetag overcomes several problems
• no tag loss or mortality – tagging is to collect tissue in situ, identify individual fish from msDNA ()
• non-reporting not such a problem - screen the commercial catch for matches to Genetagged fish
• Harvest rate - calculated from proportion ‘recaptured’ and screening fraction
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DEPARTMENT OFPRIMARY INDUSTRY, FISHERIES AND MINES
Issues - Gene tag monitoring feasibility needs lots of work
• Distribution, collection, storage, databasing of samples• Genetics - Set of DNA markers
– Efficient approach to screening (must do 1000s)– It’s not as easy as CSI!
• Database programming and analysis– dealing with large amounts of data means huge number of comparisons
• Turning results into management responses: A set of monitoring rules and control responses
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DEPARTMENT OFPRIMARY INDUSTRY, FISHERIES AND MINES
Where are we now?
• Mass data analysis - results in a few months!
• Several confirmed Genetag recaptures
• PROOF OF CONCEPT
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DEPARTMENT OFPRIMARY INDUSTRY, FISHERIES AND MINES
Cautions
The Genetag approach is proven - making it a fishery wide monitoring method will still be a challenge
• Cooperation of the fishers really helps
• IT HAS TO BE COST EFFECTIVE!
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DEPARTMENT OFPRIMARY INDUSTRY, FISHERIES AND MINES
Conclusions
• Things will change – probably more radically than they have in the past –with MANY interacting drivers
• The first problem is detecting change, so that consequences can be managed
• The second problem is managing – developing responses to anticipated change, new systems to detect changes, and managing for risk
• We have the tools! And . . .
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DEPARTMENT OFPRIMARY INDUSTRY, FISHERIES AND MINES
We work bloody hard! WE can do better than . . .
• Any questions?
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DEPARTMENT OFPRIMARY INDUSTRY, FISHERIES AND MINES
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DEPARTMENT OFPRIMARY INDUSTRY, FISHERIES AND MINES
Managing Risk in our Shark Fishery
• Additional considerations –– Illegal foreign fishing, rare unproductive species
• Trigger management actions in response to – – Changes in catch rates (e.g. reduced effort when more larger
species)
– Changes in species composition of the catch (might indicate ecological interactions)
– The biggest danger is in delaying response
• Find a better way . . .
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DEPARTMENT OFPRIMARY INDUSTRY, FISHERIES AND MINES
Harvest Strategy Management as a Framework for Managing Risk
• An agreed system in which management is more risk averse as uncertainty in status of a fishery increases
• High tier fisheries depend critically on the ability to detect and respond to changes in fish stock status. They have good information available
• Lower tier fisheries rely on risk analysis and risk containment approaches
• Fisheries are not allowed to expand unless there is prior proof of potential – i.e. cannot catch more fish unless there is a real understanding that it would be sustainable.
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DEPARTMENT OFPRIMARY INDUSTRY, FISHERIES AND MINES
Harvest strategy - Advantages
• Forces exploration of uncertainty and development of a risk averse set of response rules that are agreed BEFORE there are problems
• Thus problems are acted on in an agreed way, not put off
• There is a clear direction for information gathering and experimentation – Reducing uncertainty and risk
• There is a clear basis for cost-benefit analysis for decisions about whether such work would be of benefit.
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DEPARTMENT OFPRIMARY INDUSTRY, FISHERIES AND MINES
Opportunity: Combined genetic - conventional tagging
• Control - but much more than an experimental control
• Combo-tagged fish could give information on post-release survival and tag shedding – as well as add information on fishing and movement rates
• Recreational tagging could contribute real value in this way >1000 fish in the Darwin area have been combo-tagged!
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DEPARTMENT OFPRIMARY INDUSTRY, FISHERIES AND MINES
What Fisheries Scientists?
• Insert pictures of Jenny Ovenden and CO.