The Spatial Distribution of Fishing Effort and Short

The spatial distribution of FAD fishing
effort and short-term decision making
of tuna fishers from General Santos
City, Philippines
Edison D. Macusi, Ricardo P. Babaran, Paul Van Zwieten
1-3 September 2014
Davao City
Introduction
• FAD fishing in the Philippines is an adaptation to
save fuel costs and to attract fish
• They are deployed near the coasts and offshore
from 200m to 5000m
• Interests in spatial effort distribution has been
linked to spatially explicit measures of
management on marine ecosystems (Walters, 2000)
• Success of measures are attributed to
understanding both spatial and behavioural
aspect of fisheries (Wilen et al., 2002; Salas and Gaertner,
2004)
Introduction
• Spatial effort distribution is affected by fishers
individual decision-making (Pet Soed et al., 2001; Daw
2008)
• FAD fisheries in the Philippines mainly target
two class sizes of tuna and tuna like species
• They target both juvenile and adult tunas
• Although FADs are efficient in aggregating
tuna, their impact have become contentious
• There is a need to improve regulation of the
fishery
Objectives
• To understand the spatial fishing behavior of
handline and purse seine fishers
• Three main questions asked:
A) Fishing effort
B) Distance
C) Short and long term decision-making
Study sites (Southern Philippines)
General Santos
(150)
Methodology
A) Semi-structured interview
Information: number of days fishing, number of days not fishing, best catch, worst
catch, normal catch, short and long-term decision making, mapping exercise
B) Group workshop and interview
Information: short and long-term decision making, when to fish, where to deploy
FADs, Catch rates: best, worst, normal catch, mapping exercise
Methodology
A) Scoring of Maps
Acetates were superimposed on
google maps and fishers were free to
draw onto the acetate their FAD
fishing area
B) Decision-making
Decision-making of fishers were
explored both through surveys
and workshops/group
interviews
Results
Purse seines/ Ring net
FAD density
Handlines
FAD density
Mati
Mati
Tawi-Tawi
Davao gulf
Davao gulf
Number of fishers
Number of fishers
Mati
Tawi-Tawi
Davao gulf
Mati
Davao gulf
Results
Handlines
Purse seines/Ring net
Weighted attendance index
Weighted attendance index
Mati
Tawi-Tawi
Davao gulf
Highly dynamic, heterogeneous distribution of effort
Pockets of areas where intense effort can be found
Mati
Catch rates: normal, best, worst
Purse seines/ ring net (N=40)
Legend
Best catch
Worst catch
Normal catch
(p=0.000)
(p=0.009)
Catch rates: normal, best, worst
Handlines (N=93)
Legend
Best catch
Worst catch
Normal catch
(p=0.000)
(p=0.013)
Decision making where to fish
Factors
Factors
18%
17%
25%
Percentage
Chi2: 588.4 n=138, p=0.000
Other’s fishery
Previous catch
News of fish catch
Regulation
Lunar phase
Price of fuel
Price of fish
Weather and currents
Debts and loans
% Total Variance
Component
1
2
3
.867
.067
-.054
.800
.106
.050
.771
-.043
.234
-.713
.214
.280
.495
.190
.361
.080
.919
-.195
-.431
.785
-.004
.181
.656
.150
-.012
-.102
.939
34.826 22.819
11.411
Flow of information
Economic considerations
Fisher behaviour
Decision making where to fish
Table 3. Factors that influences decision-making of Purse
seine fishers where to fish
Factors
Y (√) / N (x)
Rank
√
3
1. Previous catch
√
1
2. Weather
√
1
3. Current
√
4
4. Lunar phase
√
4
5. News of fish catch
√
2
6. Price of Fuel
x
0
7. Price of Fish
x
0
8. Regulation
x
0
9. Other’s fishery
√
4
10. Debts/Loans
√
4
11. Fish aggregation
Decision making where to deploy FADs
Factors
18%
21%
16%
46%
Percentage
Chi2: 18.12 n=39, p=0.000
“Previous good catch in that area”
Decision making where to deploy FADs
Table 4. Factors that influences decision-making of Purse seine
fishers where to deploy FADs
Factors
Y (√) / N (x) Rank
√
3
1. Previous catch
2
2. Information from other fisher’s √
√
3
3. Accessibility
√
3
4. Availability
x
0
5. Color of water
√
3
6. Presence of Birds
x
0
7. Sonar records
x
0
8. Survey of area
x
0
9. Depth of water
x
0
10. Distance of FAD
√
1
11. Pathway of fish
√
3
12. Current
“Tunas must pass through”= good catch
Decision making when to deploy FADs
Factors
68%
16%
16%
Percentage
Chi2: 60 n=39, p=0.000
“Recent experience of good catch matters”
Decision making which FAD to fish
12%
Factors
21%
39%
28%
Percentage
Chi2: 47.851 n=138, p=0.000
Summary of key findings
1. The spatial behavior of handliners are more on opportunistic fishing
2. Handliners are very dynamic, erratic in terms of movement patterns,
they fill their fish boxes before return to port
3. The spatial behavior of purse seines/ring nets are largely predictable,
relies on calculated risks (greater investments)
4. Both fishers are heterogeneous in effort distribution and fishing
intensity: high variation in catches-temporally and spatially; diverse in
target species
5. Weather and current plays a key role in the decision making of
whether fishers will go to fish or stay at home
6. Second consideration is the economic cost of fishing operation over
distance travelled
7. FAD deployment relies more on experience of a previous catch which
must be good (business sense)
8. Selection of FADs to fish from relies on routine visits
Daghang Salamat!

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