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Transcript
Possible impact of Climate Change
on the fishery industry in Sri Lanka
P.R.T. Cumaranatunga
Dept. of Fisheries & Aquaculture
Faculty of Fisheries and Marine Sciences
& Technology
University of Ruhuna,
Matara, Sri Lanka
Sri Lanka
Vulnerable areas due to sea level rise
Observations on Temperature & Rainfall
1.5
y = 0.02x - 1.6757
1
R2 = 0.6888
0.5
0
-0.5
-1
-1.5
-2
-2.5
1901 1909 1917 1925 1933 1941 1949 1957 1965 1973 1981 1989 1997
year
Annual rainfall variability in Ratnapure
2000
1500
1000
500
0
2000
1990
1980
1970
year
1960
1950
1940
1930
1920
-1000
1910
-500
1900
RF anomaly in mm (from
1961-1990)
Tmin Anomaly in C
(from 1961-1990)
Annual minimum air Temperature anomaly trend in NuwaraEliya
Impact of global warming on the
Physicochemical parameters that would
affect the distribution & migration of tuna
• Increase in temperature of water
• Change the horizontal & vertical distribution of global
water temperatures
• Deepen the thermocline, which indicates that mixing of
surface water layers spreads down to deeper depths.
• Rise in sea level
• Change the salinity distribution
• Change thermohaline circulations (vertical & horizontal
current patterns)
• Affect the El Ninno Southern Ossilation (ENSO)
• Changes in rainfall
Thermohaline circulation caused by heating in
lower latitudes & cooling in higher latitudes
Reduction
in polar ice
Shifting
due to
global
warming
Down welling
Upwelling
Polar ice
Expected deepening
of thermocline due
to global warming
Temperature
gradient
&
thermocline
in oceans
Ocean stratification with respect to
Temperature salinity & density and its
possible directions of shifting due to global
warming
Vertical
profile of
selected
physicochemical
parameters
in the
ocean
O2 mg L-1
Global current pattern under
normal conditions
•Warm srface currents
•Cold surface currents
Up welling areas & fishing grounds
El ninno
condition
(ENSO)
Sea surface temperature anomalies in
November 2007 showing La Niña
conditions.
Blue- Temperature below average
Red- Temperature above average
Effect of global warming on
behaviour & biology of marine
fish
Effects of increased temperatures
on biology fish
• Since fish are cold blooded, when the surrounding
water warms up, metabolism speeds up
• Digest food more rapidly,
• Grow more quickly
• Have more energy to reproduce.
• But fish need more food and more oxygen to
support this higher metabolism.
• Warmer fish tend to mature more quickly,
• This speedy lifestyle is often a smaller body size
and a smaller brood.
•
At higher temperatures sex determination will be
affected (e.g. more females)
Impacts of global warming on
habitats & behaviour of fish
• Expansion and/or contraction of suitable
habitats (e.g. coral reefs, sea grass beds,
mangroves, etc.)
• Shifts in the distribution of fish stocks
through
 Alteration or reduction of feeding grounds
 Reduction in breeding grounds
 Changes in migratory circuits that connect life
stages
 Affecting successful completion of the life cycle
 Affecting successful recruitment
Impact of Global warming on
fisheries
• Climate is a major factor affecting the
productivity of key species in world fisheries.
• Changes in commercially and ecologically
important marine fish species at organismallevel & population-level
– Growth
– reproductive success
– Mortality
– Habitat
Impacts of decline of fish stocks
on other important matters
(for Sri Lanka)
• Declines in fisheries will have massive
impacts on
– Commercial fishing,
– Tourism
– Biodiversity.
Possible adaptations of fish due
to global warming
• Individual species or populations may build capacity
to adapt to changes in important abiotic and biotic
factors.
• Adaptations could include
– changes in the important life history events
(e.g., migration, spawning)
and/or
– physiological changes (e.g., thermal reaction
norms of key traits such as growth, increased
tolerance to lowered pH/ocean acidification).
Other impacts
• As global warming continues, the pressure on
fish populations will increase due to following
– Overfishing
– Pollution
– habitat loss
• Although slightly warmer water could be
tolerated by man, its effect on fish and aquatic
ecosystems, and ultimately on the global food
supply and economic stability, could be severe.
SDA-Specific dynamic action
TemperatureoC
Global warming will continuously
change the habitats of fish
• Many fish that cannot find a local solution
are already heading towards the poles as
the water becomes too warm.
• Naturally, when fish find themselves in hot
water, they head out in search of cooler
locales.
• As global temperatures rise, some fish may
be able to shift locally – by moving deeper
or by heading upriver towards cool
headwaters.
Problems faced by fish due to
migration to warm waters
• Fish that can tolerate heat will become much
more common.
• The fish that stay around will also have to
deal with new species that enter in to their
niche
How will fisheries change?
• Fisheries resources may become less predictable
as extreme weather hits more often.
• Events like the El Niño might cause a greater
impact on warm water fisheries and reef
fisheries.
• Many fisheries resources will permanently shift
location as water temperatures rise.
• Large, commercial fleets that can follow the
fisheries may not be as strongly affected as
local, small-scale fishermen, who will have to
adapt their gear and methods, travel further,
and fish longer to continue providing enough food
for their families and local markets.
Impact of Global warming on tuna &
bill fish & their fishery
Why the abundance of tuna species
has changed in a given time?
• Three categories of factors:
–factors related to changes in fishing techniques that
cause changes in species catchability (e.g., changing
the depth exploited by the longline),
–environmental (climate-linked) factors inducing spatial
changes in the distribution and movements of fish,
both in the vertical and horizontal dimensions (e.g., in
relation to the depth of the thermocline, or the
seasonal or ENSO-related extension of warm waters)
–Real changes in abundance of the stock, with low or
high levels of recruitment, in relation either to an
environmental change or to the size of the spawning
stock biomass (stock-recruitment relationship).
Effect of an abrupt change in water temperature
(25 to 15° C) on heart rate in a yellowfin tuna.
Note: that heart rate follows the change in water temperature, not
muscle temperature. Cardiac output (data not shown) follows heart
rate because of tunas’ limited ability to increase stroke volume.
Distribution of tunas and tuna-like fish
in the water
Biological characteristics of tuna in FAO-Fisheries and Aquaculture Department
http://www.fao.org/fishery/topic/16082/en#Distribution
Temperature (oC) Tolerance of Tuna & billfish species
Species
Latin Name
Ocean T(mn) T(mx) Preference
Northern Bluefin
Thunnus thynnus
A,
Southern Bluefin
Thunnus maccoyii
A,P,I
Pacific Bluefin
Thunnus orientalis
P,I
Bigeye tuna
Thunnus obesus
A,P,I
Yellowfin tuna
Thunnus albacares
A,P,I
Albacore tuna
Thunnus alalunga
A,P,I
Skipjack tuna
Katsuwonus pelamis
A,P,I
Kawakawa
Euthynnus affinis
P,I
Slender tuna
Allothunnus fallai
A,P,I
Striped Bonito
Sarda orientalis
P,I
Atlantic bonito
Sarda sarda
A,
Eastern pacific bonito Sarda chiliensis chiliensis P,
Little tunny
Euthynnus alletteratus
A,
Swordfish
Xiphias gladius
A,P,I
Indo-pacific blue marlin Makaira mazara
P,I
Atlantic blue marlin
Makaira nigricans
A,
White marlin
Tetrapturus albidus
A,
Black marlin
Makaira indica
A,P,I
Striped marlin
Tetrapturus audax
P,I
Atlantic Sailfish
Istiophorus albicans
A,
Pacific Sailfish
Istiophorus platypterus
P,I
7.63
7.42
6.98
9.25
16.35
11.29
16.63
16.5
15.5
14
12
18.8
18
8.89
19.75
20.68
21.33
16.17
16.82
19.2
20.5
26.17
22
24
26.45
27.73
23.9
29.47
30.5
19
23
27
30.5
30
27.86
29.05
30.05
27.57
30.17
25.49
27.9
27.85
20.84
18.5
21.56
23.1
22.5
24.25
18
30
24
23.2
21
26.68
Ambient water temperature tolerances and preferences for 21 species
of tuna and billfish
Bracketed numbers represent the number of sources which support the data.
Boyce Daniel (2006). Effects of water temperature on the global distribution of
tuna and billfish. Dalhousie University Halifax, Nova Scotia
Ambient water temperature tolerances and preferences for larvae, juveniles
& adults of tuna & billfish
Impact of Temperature on Species
richness with respect to tuna & bill fish
Impact of Temperature on Species
richness with respect to tuna & bill fish
in Atlantic, Pacific & Indian Oceans
Number of tuna in a sample of 50 individuals
Distribution of Temperate & Tropical Tunas
• Tropical tunas: skipjack and yellowfinI
• Intermediate tunas: bigeye
• Temperate tunas: albacore, Pacific bluefin, Atlantic bluefin and southern bluefin
Biological characteristics of tuna in FAO-Fisheries and Aquaculture Department
http://www.fao.org/fishery/topic/16082/en#Distribution
Distribution of Oceanic & Neritic Tunas
3 of the 8 species of Thunnus are found worldwide except in the Arctic Ocean.
Most bonitos and little tunas (Euthynnus spp.) are primarily neretic, ie coastal fishes,
but the distribution of individual species is often widespread.
The frigate and bullet tunas (Auxis spp.) are probably both oceanic and coastal
(Olson and Boggs, 1986).
Biological characteristics of tuna in FAO-Fisheries and Aquaculture Department
http://www.fao.org/fishery/topic/16082/en#Distribution
Impact of global warming on
the fisheries of the Indian
Ocean
• If the temperature of Indian Ocean
increases, there is a risk of losing the
important fishing grounds
• Important fisheries such as tuna fisheries will
suffer because tuna fish stocks may shift
their migratory circuits towards sub tropicasl
or temperate regions
Seasonal variation
of current pattern
in the Indian Ocean
February March
August September
Seasonnal
variations in
surface
temperatures in
the Indian Ocean
November
May
January
July
March
September
CPUE distribution pattern of yellowfin tuna
in the Indian Ocean
January
July
April
October
Pei-Fen Lee, I-Chin Chen and Wan-Nien Tseng, Distribution Patterns of Three Dominant Tuna
Species in the Indian Ocean
http://proceedings.esri.com/library/userconf/proc99/proceed/papers/pap564/p564.htm
Peak abundance of tuna
species in the Indian Ocean
Pei-Fen Lee, I-Chin Chen and Wan-Nien Tseng, Distribution Patterns of Three
Dominant Tuna Species in the Indian Ocean
http://proceedings.esri.com/library/userconf/proc99/proceed/papers/pap564/p564.htm
Peak abundance regions for albacore, bigeye
and yellowfin tunas in the Indian Ocean
.
All specioes 0;
Albacore 1-2, bigeye tuna1-3, yellowfin tuna1-4
Albacore 3-4, bigeye tuna4-6, yellowfin tuna5-8
Albacore 5-8, bigeye tuna7-10, yellowfin tuna9-11
Pei-Fen Lee, I-Chin Chen and Wan-Nien Tseng, Distribution Patterns of Three Dominant
Tuna Species in the Indian Ocean
http://proceedings.esri.com/library/userconf/proc99/proceed/papers/pap564/p564.htm
Effect of Sea surface Temperature on the
distribution of Yellowfin tuna
Pei-Fen Lee, I-Chin Chen and Wan-Nien Tseng, Distribution Patterns of Three
Dominant Tuna Species in the Indian Ocean
http://proceedings.esri.com/library/userconf/proc99/proceed/papers/pap564/p564.htm
Effect of chlorophyll concentration on the
distribution of Yellowfin tuna
Pei-Fen Lee, I-Chin Chen and Wan-Nien Tseng, Distribution Patterns of Three
Dominant Tuna Species in the Indian Ocean
http://proceedings.esri.com/library/userconf/proc99/proceed/papers/pap564/p564.htm
Possible impacts of global warming on the
coastal biodiversity and fisheries
Bleaching of corals (in thermo-sensitive corals)
Reduction of sea grass & algal beds with low
temperature tolerance
Loss of feeding and breeding grounds for fish &
other economically important coastal and marine
organisms
Alteration of migratory circuits of highly migratory
& economically important fish species (eg. Tuna, bill
fish, etc.)
Reduction of coastal land area available for
aquaculture
Reduction of beaches & sand dune ecosystems due to
coastal inundation & erosion
Action
needed
Identify the most vulnerable & easily adapted species to
climate changes.
Temperature and salinity tolerant species should be
promoted for aquaculture purposes.
Identify the changes in migratory circuits of tuna, bill
fish, etc. through biotechnological & satellite remote
sensing techniques.
Introduction of coastal & offshore mariculture in floating
cages for temperature tolerant species of tuna, grouper,
ornamental fish & other temperature tolerant species.
Soft natural barriers should be promoted as solutions for
coastal inundation and strong wave action (i.e.
establishment of artificial reefs, restoration of sand dune
vegetation, etc.
Funds should be allocated for monitoring of ecosystem
changes and for research programmes in above areas.
Photographs by P.B.T.P. Kumara
Fish culture
Captive
breeding of
reef fish
Floating cages used for
fish culture in China &
other developed countries
Ornamental fish inside
sea weed culture
enclosures
(Source: McHarg, I. L. 1995. Design with Nature)
Recommended Solutions
• Identify temperature tolerant species or
more adaptable species, populations,
varieties, etc.
• Develop temperature tolerant species
through captivity breeding (through line
breeding)
• Culture or fattening of fish in off shore
floating cages
Thank you