1. FISHERIES MODELLING AND MANAGEMENTOR
WHAT HAVE I LEARNED FROM 400+ INTERNATIONAL SCIENTIFIC FISHERIES MEETINGS?
Doug S Butterworth
MARAM (Marine Resource Assessment and Management Group)
Department of Mathematics and Applied Mathematics
University of Cape Town, Rondebosch 7701, South Africa

2. OUTLINE Why is sustainable fisheries management so difficult?
Local problems
International problems
“Ecosystem” issues
What’s coming next?
As a scientist, why bother?

3. I) WHY IS SUSTAINABLE FISHERIES MANAGEMENT SO DIFFICULT?
SUSTAINABLE UTILISATION
Pensioner must live off interest
What’s my capital?
What’s the interest rate?
Multiply the two
Don’t spend more than that!
EASY!! 3

4. THE SOURCE OF THE DIFFICULTY
THE SOURCE OF THE DIFFICULTY . FISHERIES HAVE UNCO-OPERATIVE BANK TELLERS
They won’t tell you the interest rate, which in any case is highly variable
Recruitment fluctuations
They will advise your balance only once a year, with a typically +-50% error, and in the wrong currency
Surveys (or abundance indices) are typically available annually only, their results have high variance, and their bias is unknown 4

5. WHAT NEW DO THEY BRING TO ASSIST SOLVE THE PROBLEM?
MANAGEMENT PROCEDURES (MSE – AGREE THE RULES BEFORE YOU PLAY THE GAME) .
WHAT NEW DO THEY BRING TO ASSIST SOLVE THE PROBLEM?
FEEDBACK CONTROL!
Monitor stock changes and adjust management measures (e.g. TACs) accordingly 5

6. A FINANCIAL ANALOGY $1 000 000 invested at 5% p.a.
Each year withdraw $ 
Investment sustainably maintained at $
ton fish stock grows naturally at 5% p.a.
Each year catch tons 
Sustainable exploitation: resource kept at tons

7. After 5 years, someone MAY have stolen $300 000 from your investment
You keep withdrawing $ per year
No theft
Theft
After 5 years, recruitment failure or IUU fishing MAY have reduced abundance by 30%
Catches maintained at tons per year
If this event did occur, resource is rapidly reduced

8. WHY’S THERE ANY PROBLEM?
Ask the teller for account balance.
If this has fallen to $ , reduce annual withdrawal to $ 
Sustainability maintained.
BUT
The teller will advise balance only once a year
with 50% error
Resource abundance known only through annual surveys or abundance indicies (e.g. CPUE) which have large associated errors

9. CAN YOU TELL WHETHER $300 000 WAS STOLEN FROM YOUR ACCOUNT ?
(Equivalently, whether fish abundance was reduced by 30%?)
In each of the following scenarios shown, the theft occurred in only one of the two cases
Can you tell which one?

25. IMPRESSIONS It wasn’t easy to tell
It needed usually about 20 years of new data
to be certain
By that time, account was almost exhausted
(if theft had occurred)
By the time the adverse effect of recruitment failure or IUU fishing is detectable, the resource is already heavily depleted

26. THREE STRATEGIES (MPs)
I: Withdraw $ every year
II: Withdraw 5% of the teller-advised balance
each year
III: Withdrawal this year = 80% last year’s
withdrawal + 1% teller’s (erroneous) balance
Strategy must “work” whether or not theft occurred

27. Annual Withdrawal I II III
No theft
Theft I II
III

28. Balance in Account I II III
No theft
Theft I II
III

29. Annual Withdrawal I II III
No theft
Theft I II
III

30. Balance in Account I II III
No theft
Theft I II
III

31. “Feedback control” (MP basis)
PERFORMANCE
I: Going bankrupt if theft occurred
II: Stabilises balance in account, but annual
withdrawals too variable
III: Best of the three – stabilises balance
without too much change from year to year
Formula III automatically corrects for effect of recruitment failure/IUU fishing if it occurred.
“Feedback control” (MP basis)

32. II) LOCAL PROBLEMS EVEN DATA-RICH IS OFTEN INFORMATION-POOR
We’d like to be at an abundance that provides the Maximum Sustainable Yield (US Magnuson-Stevens Act)
But how well do we know what that is – implications for rebuilding – will less catch today really deliver more tomorrow?
It’s unsurprising that industry can be sceptical. 32

33. II) LOCAL PROBLEMS ECOLABELLING
This has enhanced the attention paid to science by fisheries decision makers
But is there undue pressure from some ENGOs for more stringent criteria (fair practice to move goalposts)?
Will the system survive this, and consistency problems?
Can developing countries hope to achieve these standards (which they view as unfair trade restriction practice)?
Losing the plot? – no actual incentive to improve most of the world’s poorer managed fisheries 33

34. II) LOCAL PROBLEMS THE SCIENTISTS – MANAGERS DIVIDE
Managers often fail to master the underlying scientific principles/concepts – frequently because they are too “position-mobile” to have the time to gain experience
Scientists are often unable to communicate effectively outside the scientific sphere
Scientists should evaluate the implications of alternative action options (e.g. greater catch vs lower resource risk) amongst which managers then choose
BUT
Managers ask: “Which of these options do the scientists recommend?” 34

35. III) INTERNATIONAL PROBLEMS
POOR CONSERVATION PERFORMANCE OF REGIONAL FISHERIES MANAGEMENT ORGANISATIONS (RFMOs)
IOTC – 19 years old and yet to set a TAC
The allocation problem (no boss)
CITES – Does/Should it have a role?
Listings “never” reverse-able
The Fisheries vs Environment Ministries clash
Industries dominate RFMOs – ENGOs dominate CITES
The charismatic megafauna aspect 35

36. III) INTERNATIONAL PROBLEMS
POOR CONSERVATION PERFORMANCE OF REGIONAL FISHERIES MANAGEMENT ORGANISATIONS (RFMOs)
Problems of attaining consensus ->
Necessary action is delayed
International litigation (ITLOS/ICJ)
How well are these bodies suited to dealing with essentially scientific issues?
But how well suited are scientists to make “objective” decisions in an inexact field with high levels of advocacy/hidden agendas and employment at risk
US SSCs – scientists determine policy implementation 36

37. IV) “ECOSYSTEM” ISSUES
POOR RELIABILITY OF MULTI-SPECIES MODELS
Will reducing fish catches benefit natural predators?
Will culling predators allow for greater fish catches?
Precautionary Principle – opportunistic use
ECOSYSTEM ASPECTS OF FISHING (EAF)
(Ecosystem Based Fisheries Management)
Bycatch/Biological interactions/Habitat conservation/Social issues/ ……
Many different interpretations in practice/Many words?/
Is this diffusing necessary focus? 37

38. IV) “ECOSYSTEM” ISSUES
MARINE PROTECTED AREAS (MPAs)
Widely and strenuously advocated (especialy by ENGOs)
They have their value/uses – effort limitation, can benefit recovery of near-sessile species
BUT
They are NOT a panacea for all fishery ills
The primary need is for improved fisheries management 38

39. V) WHAT’S COMING NEXT? INTERNATIONAL MANAGEMENT (RFMOs)
Will the UN step in?
RECOVERING DEPLETED STOCKS
Will a rising real cost of fuel be the primary determinant?
ECOLABELING
Will this initiative implode?
SCIENTISTS vs MANAGERS
Pre-agreed decision rules (MPs) vs Flexibility/negotiation
Which will win? A continued risk of “too little too late”? 39

40. VI) AS A SCIENTIST, WHY BOTHER?
INTERACTIONS WITH MANY DISCIPLINES
Applied Mathematicians, Botanists, Computer scientists, Microbiologists, Oceanographers, Statisticians, Zoologists
Accountants, Economists, Engineers, Social scientists
Lawyers, Judges, Criminals (poachers), Industry, ENGOs, Bureaucrats, Journalists, Politicians
Add the international dimension
A NEW PROBLEM EVERY OTHER DAY
CONTROVERSY
Can lead to filibustering but promotes better science
ANYTHING BUT A BORING LIFE 40

41. Thank you for your attention
And thanks for assistance from the Lowell-Wakefield Symposium to visit Anchorage