Environmental impact of
fishing and estimation of carbon
foot printing due
to fishing

Environmental impact of fishing
 The environmental impact of fishing includes issues such as the
availability of fish, overfishing, fisheries, and fisheries management;
as well as the impact of fishing on other elements of the
environment, such as by-catch. These issues are part of marine
conservation, and are addressed in fisheries science programs.
 There is a growing gap between the supply of fish and demand, due
in part to world population growth.
 Similar to other environmental issues, there can be conflict between
the fishermen who depend on fishing for their income, and fishery
scientists whose studies indicate that if future fish populations are to
be sustainable then some fisheries must reduce or even close.

The journal Science published a four-year study in November 2006, which
predicted that, at prevailing trends, the world would run out of wild-caught
seafood in 2048.
The scientists stated that the decline was a result of overfishing, pollution and
other environmental factors that were reducing the population of fisheries at the
same time as their ecosystems were being annihilated.
Yet again the analysis has met criticism as being fundamentally flawed, and
many fishery management officials, industry representatives and scientists
challenge the findings, although the debate continues. Many countries, such as
Tonga, the United States, Australia and Bahamas, and international management
bodies have taken steps to appropriately manage marine resources
Predictions…..

Effects on Marine habitat
 Some fishing techniques also may cause
habitat destruction. Blast fishing and cyanide
fishing, which are illegal in many places,
harm surrounding habitat.
 Bottom trawling, the practice of pulling a
fishing net along the sea bottom behind
trawlers, removes around 5 to 25% of an
area's seabed life on a single run
Effect of bottom trawling on the
ocean floor

Blast fishing Torn nets along the sea bed
Cyanide fishing

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 Several habitats are extremely vulnerable to
anthropogenic disturbances that often include
fishing.
 Intertidal and shallow subtidal communities are
diverse and resilient to small scale perturbations;
they are, however, vulnerable to large scale
disturbances because they cover very limited areas,
are near population centres, and in most areas are
intensely fished.
 Reef habitats are often isolated by soft bottom
habitats; they represent small islands that are
heavily exploited and disturbed by people Lost trap degrading coral

BYCATCH
 Bycatch is perhaps the most serious general
environmental impact of modern fisheries.
 Because the process is out of sight of the public
and there are few objective studies, the data base is
inadequate and attention to the problem has been
limit

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 Most of the species particularly vulnerable to bycatch such as mammals, sea
birds, turtles, and sharks occur in aggregations.
 ICES groups studying ecosystem effects of fishing activities have attempted to
compensate for these problems, and these efforts continue (Anon., 1991b).
 It is considered that all efforts to evaluate bycatch and environmental effects of
heavy fishing on natural systems are too late because most sensitive species have
long been impacted, leaving no concept of natural relationships or patterns.

Bycatch mainly includes..
Pelagic communities
Most pelagic bycatch occurs with net fisheries
The incidental catch of mammals, turtles and birds are of
special concern because they are high profile species often
protected by legislation
Mammals
• Net entanglements of the greatly depleted North Atlantic
right whale are very serious; more than 50% of these rare
whales are estimated to bear marks and scars indicating that
they have encountered fishing gear (Kraus, 1990)

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• The best known example of incidental take is that by the tuna purse seine
fishery in the Pacific which is estimated to have taken over 6 million
porpoise by 1987 with clear evidence that the porpoise populations were
substantially reduced
• The high seas drift net fishery is another high profile example of
incidental take that resulted in threatened UN action before it was closed
in the North Pacific.
• This fishery covered several large geographical areas, had different target
species, and different levels of bycatch (Alverson et al., 1994).

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Turtles Sea
Turtles and other marine organisms that feed on or around target
fishery resources frequently get caught as bycatch, are inadvertently
killed or injured through contact with fishing gears
Seabirds
Tuna long line fishermen in the southern hemisphere are thought to
take many tens of thousands of albatrosses and have been implicated in
a massive annual kill of at least 44000 wandering albatross (Croxall,
1990).
The actual annual take may be twice as high (Brothers, 1991).

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Several authors have discussed the relationship
between fisheries and seabirds in the California
Current and in Alaskan waters (Ainley and Hunt, 1991,
Ainley and Sanger, 1979; DeGrange et al., 1993;
Salzman, 1989; Springer, 1992; Takekawa et al.,
1990), and there is a great deal of evidence of heavy
incidental catch of seabirds as well as inferential
evidence of resource competition between seabirds and
fisheries. Ainley et al. (1994

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Benthic communities
 There are many types of trawls, dredges, and traps that sit
on or are dragged over the sea floor.
 Bottom fishing gear is not selective and bycatch is a
serious problem.
 The effects on the sea bottom include impacts such as
scraping and ploughing the bottom to substratum depths
of 30 cm as well as causing resuspension of sediment and
destruction of many bottom organisms

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 Report that a beam trawl can remove bites at
least 6cm into the bottom, and the boards of otter
trawls get as deep as 15cm.
 They report long lists of benthic species
destroyed, and that most good areas are trawled
over many times a year.
 Their study area was fished at least three times
per year, and their experimental three-fold
trawling reduced echinoderms, polychaetes and
molluscs by 10-65%.

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Deep-sea
Deep-sea habitats are subject to increasing amounts of fishing
.
These communities are characterized by life-history
adaptations such as slow growth, extreme longevity, delayed
age of maturation, and low natural adult mortality.
Also they often are characterized by fragile structures that
have important community roles (Levin et al., 1991).
Such adaptations are characteristic of systems with low
productivity and turnover; they are extremely vulnerable to
human intervention such as fishing (Messieh et al., 1991;
Thiel and Schriever, 1990), and there is a considerable risk
attendant to any disturbance in this habitat.

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Coral reefs
 The effects of fishing on coral reefs vary from
altering the size structure of target fish to cascading
effects on other reef fish species composition,
biomass, and density (Sebens, 1994; Hughes, 1994)
 Russ and Alcala (1989) document many direct and
indirect effects of intense fishing on abundances,
species richness, and distribution of other fishes as
well as other benthic invertebrate species.

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 Fishing on coral reefs has become extremely
damaging to the reefs themselves. A recent
international workshop of coral reef experts
ranked overfishing as the most important hazard
(Roberts, 1993), especially when dynamite is
used to blast the reefs and stun fish.
 This involves the loss of the reef structure that
offers important protection from storm waves as
well as protection from predators, breeding and
nursery areas, etc.
 Nonselective poisons also have been used to kill
fishes; all have widespread community
consequences (Saila et al., 1993).

Secondary effects of discards
 ICES reports document that in some fisheries there can be very high proportions
of discard from target species processed at sea.
 This material is returned to the sea where crabs, fish, mammals and birds often
aggregate to consume it.
 This has certainly affected the natural behaviour of the scavenging species such
as the fulmars in the late 1950s (Anon., 1991b).
 Because only some species utilize this resource, it has a selective effect on the
communities and may put other species at a competitive disadvantage.

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 In most fisheries the vast majority of discarded organic
material is from bycatch.
 Large amounts of biomass is discarded; this affects marine
ecosystems in the same way as does organic pollution from
other
 Human activities and often has many secondary effects.
Northridge (1991) reviewed several studies that document
benthic effects of discarded bycatch.

Case studies on bycatch discard effect on
benthic fauna
Extrapolation of the few good studies suggested that the total discard biomass approximates
and often far exceeded that of the landings.
For example,
 Jones (1992) reviews Australian data collected by Wassenberg and Hill (1990) showing
that prawn trawlers discard 3000 tons of material, mostly crustaceans and echinoderms, for
each 500 tons of prawns; most of this discard sinks to the seafloor potentially to cause
oxygen depletion problems.
 One study in Norway (Oug et al., 1991) reported far-reaching effects on the benthic
community that lasted at least 3 years.

Estimation of carbon foot printing due to
fishing

The concept name of the carbon footprint originates from ecological
footprint, discussion, which was developed by Rees and Wackernagel
in the 1990s which estimates the number of "earths" that would
theoretically be required if everyone on the planet consumed resources
at the same level as the person calculating their ecological footprint.
However, given that ecological footprints are a measure of failure,
Anindita Mitra (CREA, Seattle) chose the more easily calculated
"carbon footprint" to easily measure use of carbon, as an indicator of
unsustainable energy use.
Measure of carbon…

 In Indian marine fisheries, the enhanced fishing effort and efficiency in the last five
decades has resulted in substantial increase in diesel consumption, equivalent to CO2
emission of 0.30 million tonnes (mt) in the year 1961 to 3.60 mt in 2010.
 For every tonne of fish caught, the CO2 emission has increased from 0.50 to 1.02 t
during the period.
 Large differences in CO2 emission between craft types were observed.
 In 2010, the larger mechanized boats (with inboard engine) emitted 1.18 t CO2/t of
fish caught, and the smaller motorized boats (with outboard motor) 0.59 t CO2/t of
fish caught.
 Among the mechanized craft, the trawlers emitted more CO2 (1.43 t CO2/t of fish)
than the gillnetters, bagnetters, seiners, liners and dolnetters (0.56–1.07 t CO2/t of
fish).
 There is scope to reduce CO2 by setting emission norms and improving fuel
efficiency of marine fishing boat
Indian scenario of carbon release in
marine fishing sector

GHG calculation
 In order to carry out calculations to determine the global warming potential of the
product, NGA guidelines were followed.
 The theory behind the calculation method details that the principle greenhouse gas
generated by the combustion of fossil fuels for energy is carbon dioxide.
 Hence the quantity of GHG produced is directly relatable to the carbon content of the
fuel and the degree that the fuel is fully combusted.
 NGA emission factors were used throughout all the calculations which can be found in
the NGA publication.
For the emissions generated by transport (whether it is by road, rail, marine or air) the
following equation was used:
Eii =
1000
Where:
Eij is the emission of gas type, carbon dioxide, methane or nitrous oxide, from fuel type
(CO2-e tones);

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Qi is the quantity of fuel type (kilolitres or gigajoules) combusted for
transport energy purposes;
ECi is the energy content factor of fuel type (gigajoules per kilolitre or per
cubic metre) used for transport energy purposes;
EF ijoxec is the emission factor for each gas type (which includes the effect
of an oxidation factor) for fuel type (kilograms CO2-e per gigajoule) used
for transport energy purposes.

Trawler..
 In 2010, trawlers expended 35.58 million fishing hours, with catch rate of
44.4 kg/h (Table 3). Trawlers contributed 58.7% to the landings, and 71.1%
to the CO2 emission by the mechanized sub-sector.
 CO2 emission rate by trawlers was 63.5 t per fishing hour. In the
mechanized sub-sector, the CO2 emission intensity was highest for trawlers
(1.43 t CO2/t of fish caught) and considerably low for other craft types
(0.56–1.07 t CO2/t of fish caught).
 The average CO2 emission by the mechanized sub-sector was 1.18 t CO2/t
of fish caught in 2010.
 The motorized sub-sector expended 26.12 million fishing hours, with a
catch rate of 27.2 kg/h (Table 3), and contributed 20.1% to the overall
landings.
 CO2 emission rate by the motorized sub-sector was 16.1 t per fishing hour;
the sub-sector emitted 0.59 t CO2/t of fish caught 2010.

Issues facing fisheries..
In addition to releasing more quantities of CO2 into the atmosphere, the increasing fuel
consumption over time indicates the following issues facing fisheries:
(1) Increasing fuel consumption directly increases fishing
cost and price of fish.
• Fuel cost accounts for 50–54% of operating cost of mechanized boats , and 36–44%
of operating cost of motorized boats17.
• Majority of fish types, which form staple diet, is becoming unaffordable to common
people due to increasing fishing cost.

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(2) Use of more energy by contemporary fisheries shows increasing scouting time as a result
of resource scarcity.
• Availability of abundant fossil energy (even though it is becoming costly) would enable
contemporary fisheries to continue until fish stocks collapse.
(3) To sustain marine fisheries, India is implementing Marine Fishing Regulation Act.
• One of the prominent instruments of the act is closure of mechanized fishing for 45 days
every year, which is being followed for the last 12–25 years in different regions along the
coast.
• Analysing the performance of fisheries before and after implementation of seasonal ban,
Vivekanandan et al.18 concluded that the ban has helped stabilizing the annual fishing
hours and has provided short-term benefits to increase the catches, but has not helped
improving the stock biomass. Increasing fuel consumption, as observed in the present
analysis, shows that stabilization of fishing effort is offset by increasing fishing efficiency.

Fuel burning
 It has been estimated that fossil-fuel burning by global fisheries is 42.4
mt, representing 1.2–3.5% of global oil consumption, releasing
approximately 134 mt of CO2 into the atmosphere at an average of 1.7 t
of CO2/t of live weight landed product3,20.
 Our estimate on emission by marine fishing boats in India (3.6 mt of
CO2) and fish production from marine capture fisheries (3.53 mt) shows
that India contributes 2.7% and 3.9% to the global marine fisheries CO2
emission (134 mt) and fish production (90 mt) respectively.
 Considering global estimate of 1.7 t CO2/t of live weight landed, India’s
emission intensity (1.02 t CO2/t of fish landed) is low by about 40% per
tonne of live weight landed.

CONCLUSION..
With the current trend for increased awareness of global warming and its
effects on the environment
Individuals and corporations can take a number of steps to reduce their
carbon footprints and thus contribute to global climate mitigation.
They can purchase carbon offsets (broadly stated, an investment in a
carbon-reducing activity or technology) to compensate for part or all of
their carbon footprint.
If they purchase enough to offset their carbon footprint, they become
effectively carbon neutral.

Reference..
1. Environmental effects of marine fishing by PAUL K. DAYTON Scripps Institution of
Oceanography, La Jolla. CA 92093, USA SIMON F. THRUSH National Institute of Water
and Atmosphere, PO Box 11-11.5, Hamilton, New Zealand M. TUNDI AGARDY World
Wildlife Fund, 1250 24th St. NW, Washington, DC 20037, USA and ROBERT J.
HOFMAN Marine Mammal Commission, 182.5 Connecticut Ave. NW, Washington, DC
20009, USA
2. Carbon footprint by marine fishing boats of India
E. Vivekanandan1,*, V. V. Singh2 and J. K. Kizhakudan1
Central Marine Fisheries Research Institute, Chennai 600 028, India
Central Marine Fisheries Research Institute, Mumbai 400 059, India

3. Estimating the Carbon Footprint Tuna Fisheries. Raymond R. Tan, Ph.D.
and Alvin B. Culaba, Ph.D.
4. https://en.wikipedia.org/wiki/Carbon_footprint
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