INTRODUCTION
The
ocean is affected by more or less regular natural variations. The primary
source of food from the oceans is from capture fisheries and aquaculture. The
biological productivity which fisheries exploit varies from place to place and
over time in relation to oceanographic conditions which change naturally, from
year to year and seasonally (Borms,
2006).
Some natural fluctuations are less frequent, changing only after
decades. In addition, the oceanic environment is affected by long term global
climate change caused by a combination of natural processes and human impacts,
such as the emission of greenhouse gasses. Any effects of such climate change
on fisheries will occur in a sector already characterized on a global scale by
full utilization, overcapacity of usage and sharp conflicts between fleets and
among competing uses of marine ecosystems (Fletcher, 2002) .
Climate change
impacts are likely to amplify natural variations and to exacerbate existing
stresses and on marine fish stocks, notably fishing pressure, diminishing
wetlands and nursery areas, and pollution, In the oceans, climate change is
expected to result in increases in sea surface temperature, global sea level
rise, decreases in sea-ice cover and changes in salinity, wave conditions, and
ocean circulation.
On land climate change will affect the availability of
water, river flow regimes, size of lakes, and the needs of water for other
activities competing with fisheries. These changes in turn will have an impact
on the biological productivity of aquatic ecosystems and on fisheries; an
expected impact of global climate change is an increase in the variability of
environmental conditions (Alongi and McKinnon, 2005).
Definition of key terms
Environment
literally means surrounding and everything that affect an organism during its
lifetime is collectively known as its environment. In another words
“Environment is sum total of water, air and land interrelationships among
themselves and also with the human being, other living organisms and property”
Environmental change
is defined as a change or disturbance of the environment caused by human
influences or natural ecological processes (Johnson, D. L, 1997).
A fishery
is an entity engaged in raising or harvesting fish which is determined by some
authority to be a fishery (Fletcher, W. J, et
al, 2002).
THE WAYS IN WHICH ENVIRONMENTAL
CHANGES CAN AFFECT FISHIRIES
Sea
surface temperature Fish body temperature is moderated by water
temperature. Increasing sea temperatures can affect important biological
processes of fish including growth, reproduction, swimming ability and behavior. Reproduction is only possible in a
narrow temperature range, and therefore could be affected by the forecast
temperature rises associated with climate change and cause low reproduction (Abraham
and Sydeman, 2004). Therefore fisheries will affect much by low production of
fish which resulted by low reproduction.
Ocean acidification Ocean
acidification which is a change in ocean chemistry is also likely to impact
fish reproductive processes. Fish eggs are more sensitive to pH changes than
fish adults, and thus the population numbers may dwindle if this impact is
significant. Ocean Acidification has
also been shown to reduce the ability of fish larvae to find suitable habitat
and find their way home. Lots of
species of fish live in and around coral reefs, and most feed on the microbes
in the water, which provide fish with their carbon requirements (Abraham, and
Sydeman, 2004). In general, the overarching affects of ocean acidification on
coral formation and the abundance of carbon in the food chain will impact fish
species through habitat and food availability. Hence fisheries affected much
with low reproduction and cause low production of fish
Sea level rise
The projections for sea level rise in and around the Great Barrier Reef suggest
much of the coast line will be inundated with water, resulting in major changes
to mangrove and sea grass beds in these areas. These habitats provide
protection and food resources for juvenile fish (Antonov, et al, 2002). There
are also species of fish on the Great Barrier Reef that live in both freshwater
and saltwater habitats and changes to the pathways between these two habitats
will make moving between them difficult for those species,
Irrigation system
the system of irrigation affects fisheries especially those who deal with
River, Dam, and Lake, where by people tape water from Main River and distribute
into small streams in their famers and also make deforestation around the river
for the purpose of Agriculture activities. Therefore through that process it
cause fall level of river water and cause destruction of fish habitant hence shortage
of fish production
Natural calamities,
Extreme natural events such as floods, tornadoes, hurricanes and earthquakes
can have catastrophic human, environmental and economic impacts.
Tsunamis—triggered by underwater seismic activity can be amongst the most destructive.
For instance, the series of tsunamis that occurred on 26th December 2004
following an undersea earthquake off the west coast of Sumatra, Indonesia, was
one of the deadliest natural disasters in recorded history (Lay et al. 2005).
Approximately 230,210 people were killed across 14 countries, including 168,000
in Indonesia alone. The catastrophe also had a huge environmental impact,
affecting ecosystems across the entire ocean basin and even flooded a colony of
King Penguins Aptenodytes patagonicus in the Crozet Archipelago some 6,500 km
from the earthquake epicentre (Viera et al. 2006).
Travel and access to resources,
Changing water levels, fish movement patterns, and weather conditions all
create challenges for local harvesters to meet their subsistence needs.
Residents from both communities noted that the river levels are lower on
average during the open water season, partly because of changing precipitation
patterns. This change affects transportation and access to important fishing
locations (Fletcher, 2002). Boats commonly become stuck on the bottom or hit
rocks while traveling, often causing prohibitively expensive damage to the
lower units of engines. Families travel to fish camps during the spring and
fall to pursue several species of whitefish; residents now struggle to
determine when to travel to their fish camps to catch the fish runs. Several
experienced fishermen described how they missed the bulk of the fish moving by
their camp in the recent past, arriving either too early or, more commonly,
after the fish had already passed. Faster spring break-up limits the amount of
time available for spring ice fishing, which provides a desirable source of
fresh protein after the long winter. Increasingly warmer weather during spring
greatly impedes the harvest of quality fish, because of warmer water
conditions.
Conclusion
Many
governments and intergovernmental organization around the world have
responsible to protect environment so as to reduce the environmental changes,
through that the nations should forms bodies that implement fisheries
management policies designed to curb the environmental impact of fishing. That
policy must aims to control the human activities that may completely decrease a
fish stock or washout an entire aquatic environment. These laws include the
quotas on the total catch of particular species in a fishery.
REFERENCES
Johnson,
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terms".
Journal of Environmental Quality
Fletcher,
WJ; Chessonio, J; Fisher, M; Sainsbury KJ (2002) The "How To" guide for wild
capture fisheries. National
ESD reporting framework for Australian fisheries:
FRDC Project
Abell,
R., Thieme, M. and Lehner, B. 2002.
Ecoregion conservation for freshwater systems,
with a focus on large rivers,
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C.L. and Sydeman, W.J. (2004). Ocean
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and vulnerability. Contribution
of Working Group II to the Fourth Assessment Report
of the Intergovernmental Panel on Climate Change, Cambridge
University Press
Alongi,
D.M.and McKinnon, A.D. (2005). The
cycling and fate of terrestrially-derived sediments
and nutrients in the coastal
zone of the Great Barrier Reef shelf. Mar. Pollut
Antonov,
J. I., Levitus, S. and Boyer, T.P. (2002). Steric
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and Borms (2006). "Impacts of Biodiversity Loss on Ocean Ecosystem
Services retrived on 7 Apri
2014
Written By AUSI CHIWAMBO (2014)-Teofilo Kisanji University
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