Upwelling occurs when dense, cooler, nutrient-rich water rises to the ocean surface, replacing warmer surface water. This stimulates phytoplankton growth and fisheries. The seminar discusses the mechanisms, types, and effects of upwelling, including coastal upwelling driven by wind that transports water at a 45 degree angle and the Coriolis effect. Major upwelling regions support productive fisheries, like the anchovy fishery off Peru yielding up to 10 million metric tons annually. Upwelling regions comprise only 1% of ocean area but provide 50% of fisheries catch due to high nutrient levels fueling marine life.

1. FACULTY OF FISHERY SCIENCES
A SEMINAR ON
UPWELLING AND FISHERIES
PRESENTED BY:
SOURAV BHADRA
B.F.Sc 3rd yr. 2nd sem.
ROLL NO. F/2016/29
PRESENTED TO:
Prof. t.s.Nagesh
Course teacher
DEPT. OF FRM

2. INTRODUCTION:
 What is upwelling?
 Upwelling is an oceanographic phenomenon that involves
wind-driven motion of dense, cooler, and usually nutrient-rich
water towards the ocean surface, replacing the warmer,
usually nutrient-depleted surface water.
 The nutrient-rich upwelled water stimulates the growth and
reproduction of primary producers such as phytoplankton.
Due to the biomass of phytoplankton and presence of cool
water in these regions, upwelling zones can be identified by
cool sea surface temperatures (SST) and high concentrations
of Chlorophyll-a
 In turn this two factors helps fishermen to identify the
PFZ(Potential Fishing Zone)

3. Mechanisms:
 The three main drivers that work together to cause upwelling are wind,
Coriolis effect, and Ekman transport.They operate differently for different
types of upwelling, but the general effects are the same.
 In the overall process of upwelling, winds blow across the sea surface at a
particular direction, which causes a wind-water interaction. As a result,the
water is transported a net of 90 degrees from the direction of the wind due to
Coriolis forces and Ekman transport.

4.  Ekman transport causes the surface layer of water to move at about a
45 degree angle from the direction of the wind, and the friction
between that layer and the layer beneath it causes the successive layers
to move in the same direction. This results in a spiral of water
movement down the water column.
 Then, it is the Coriolis forces that dictate which way the water will
move; in the Northern hemisphere, the water is transported to the right
of the direction of the wind. In the Southern Hemisphere, the water is
transported to the left of the wind.

5. TYPES OF UPWELLING:
 There are five types of upwelling:
 Coastal upwelling,
 Large-scale wind-driven upwelling in the ocean interior,
 Upwelling associated with eddies,
 Topographically-associated upwelling, and
 Broad-diffusive upwelling in the ocean interior.

6. Coastal Upwelling:
 Coastal upwelling is the best known type of upwelling, and the
most closely related to human activities as it supports some of the
most productive fisheries in the world.
 This upwelling process occurs at a rate of about 5–10 meters per
day, but the rate and proximity of upwelling to the coast can be
changed due to the strength and distance of the wind.
 Coastal upwelling exists year-round in some regions, known as
major coastal upwelling systems, and only in certain months of the
year in other regions, known as seasonal coastal upwelling
systems. Many of these upwelling systems are associated with a
relatively high carbon productivity and hence are classified as
Large Marine Ecosystems

7. Contd……
 Worldwide, there are five major coastal currents associated with
upwelling areas: the Canary Current (off Northwest Africa), the
Benguela Current (off southern Africa), the California Current (off
California and Oregon), the Humboldt Current (off Peru and Chile),
and the Somali Current (off Somalia and Oman).
 All of these currents support major fisheries. The four major eastern
boundary currents in which coastal upwelling primarily occurs are the
Canary Current, Benguela Current, California Current, and Humboldt
Current.
 The Humboldt Current or the Peru Current flows west along the coast
of South America from Peru to Chile and extends up to 1,000
kilometers offshore.These four eastern boundary currents comprise the
majority of coastal upwelling zones in the oceans.

8. Variations:
 Upwelling intensity depends on wind strength and seasonal
variability, as well as the vertical structure of the water, variations
in the bottom bathymetry, and instabilities in the currents.
 In temperate latitudes, the temperature contrast is greatly
seasonably variable, creating periods of strong upwelling in the
spring and summer, to weak or no upwelling in the winter. For
example, off the coast of Oregon, there are four or five strong
upwelling events separated by periods of little to no upwelling
during the six-month season of upwelling.
 In contrast, tropical latitudes have a more constant temperature
contrast, creating constant upwelling throughout the year. The
Peruvian upwelling, for instance, occurs throughout most of the
year, resulting in one of the world's largest marine fisheries for
sardines and anchovies.

9. Effects of Upwelling on Fishery
 Biodiversity and productivity:
 Since upwelling regions are important sources of marine productivity, and
they attract hundreds of species throughout the trophic levels, the diversity
of these systems has been a focal point for marine research.
 While studying the trophic levels and patterns typical of upwelling
regions, researchers have discovered that upwelling systems exhibit a
wasp-waist richness pattern. In this type of pattern, the high and low
trophic levels are well-represented by high species diversity. However, the
intermediate trophic level is only represented by one or two species.
 This intermediate trophic layer, which consists of small, pelagic fish
usually makes up about only three to four percent of the species diversity
of all fish species present. The lower trophic layers are very well-
represented with about 500 species of copepods, 2500 species of
gastropods, and 2500 species of crustaceans on average. At the apex and
near-apex trophic levels, there are usually about 100 species of marine
mammals and about 50 species of marine birds.

10. Contd……
 The vital intermediate trophic species however are small pelagic fish
that usually feed on phytoplankton. In most upwelling systems, these
species are either anchovies or sardines, and usually only one is
present, although two or three species may be present occasionally.
These fish are an important food source for predators, such as large
pelagic fish, marine mammals, and marine birds.
 Although they are not at the base of the trophic pyramid, they are the
vital species that connect the entire marine ecosystem and keep the
productivity of upwelling zones so high.The food chain follows the
course of:
 Phytoplankton → Zooplankton → Predatory zooplankton → Filter
feeders → Predatory fish → Marine birds, marine mammals

11. Animal movement:
 The second major consequence of upwelling involves its effect
on animal movement. Upwelling affects the movement of
animal life in the area. Tiny larvae—the developing forms of
many fish and invertebrates—can drift around in ocean
currents for long periods of time. A strong upwelling event can
wash the larvae far offshore, endangering their survival.
 Therefore, upwelling can be a mixed blessing to
coastal ecosystems. It can infuse coastal waters with
critical nutrients that fuel dramatic productivity, but it can
also rob coastal ecosystems of offspring required to
replenish coastal populations.

12. Fisheries in upwelling regions — with special reference to peruvian
waters:
 A 25,900-square-kilometer (10,000-square-mile) region off the
west coast of Peru,undergoes continual coastal upwelling and is
among the richest fishing grounds in the world.
 The anchovy population that is the basis of the Peru fishery,is a
phytoplankton feeding species, supported by an upwelling based
ecosystem. The fish is very short-lived and grows rapidly — both
criteria for high turnover rate — high yield fisheries.
 The maximum sustainable yield(MSY) is around 10 million metric
tons.

13. Contd…..
 Upwelling generates some of the world’s most fertile
ecosystems. Overall, coastal upwelling regions only
cover 1 percent of the total area of the world’s oceans,
but they provide about 50 percent of the fish harvest
brought back to shore by the world’s fisheries.

14. Conclusion:
 Deep ocean water is more nutrient-rich than surface water simply
because things (nutrients, plankton carcasses, fish carcasses) in the
ocean sink.
Upwelling brings those lost/sunk nutrients back to the surface,
which creates "blooms" of algae and zooplankton, which feed on
those nutrients. These blooms then become feeding grounds for
plankton feeders, then fish, etc, sustaining ocean life that lives near
the surface.

15. Reference:
 https://www.nationalgeographic.org/encyclopedia/upwelling
 https://en.wikipedia.org/wiki/Upwelling
 https://oceanexplorer.noaa.gov/facts/upwelling.html
 https://www.quora.com/Why-is-upwelling-important-to-marine-life
 https://www.nwfsc.noaa.gov/research/divisions/fe/estuarine/oeip/db-
coastal-upwelling-index.cfm
 Sarhan T, Lafuente JG, Vargas M, Vargas JM, Plaza F. (1999). Upwelling
mechanisms in the northwestern Alboran Sea. Journal of Marine
Systems
 Lalli, C.M., Parsons, T.R. (1997) "Biological Oceanography: An
Introduction" Oxford: Elsevier Publications.

16. THANK YOU