FisheryFishery

Fishing makes its greatest contribution Fishing makes its greatest contribution to the economy when it is harvested as to the economy when it is harvested as a food source. a food source.

This is the This is the commercialcommercial fishery fishery

Fishery cont.Fishery cont.

It is estimated that over 100 million It is estimated that over 100 million people in developing countries people in developing countries depend on the fishery for their depend on the fishery for their livelihoodlivelihood

In recognition of the fact that all fish In recognition of the fact that all fish species are a part of the oceans food species are a part of the oceans food chains, sustainable use is beginning chains, sustainable use is beginning to be promoted.to be promoted.

A balance is needed to so that one A balance is needed to so that one species does not outstrip the food species does not outstrip the food supply available to the system as a supply available to the system as a whole.whole.

When humans harvest fish resources, When humans harvest fish resources, however, there is a risk of however, there is a risk of overexploitation and a consequent overexploitation and a consequent disruption to the balance of nature.disruption to the balance of nature.

The 4 major fishing The 4 major fishing regions are: regions are:

North east Atlantic North east Atlantic (England/Norway); (England/Norway);

North west Pacific North west Pacific (Japan); (Japan);

West central Pacific West central Pacific (China/Indonesia); (China/Indonesia);

South east Pacific South east Pacific (Western South (Western South America)America)

Continental Shelves Continental Shelves Most fishing grounds are found on Most fishing grounds are found on

continental shelves for 2 reasons.continental shelves for 2 reasons. The shallow waters of the self make The shallow waters of the self make

harvesting more cost effective.  The fish harvesting more cost effective.  The fish have to be landed on shore for human use so have to be landed on shore for human use so the regions closer to shore are fished most the regions closer to shore are fished most profitably.  profitably. 

Most of the fish are on the continental Most of the fish are on the continental shelves.  The shallow waters of the shelf shelves.  The shallow waters of the shelf promote plankton production which serve as promote plankton production which serve as the base of the marine food web including the base of the marine food web including fish. fish. Shallow water ensures enough light for Shallow water ensures enough light for

phytoplankton and effective circulation of phytoplankton and effective circulation of nutrients. nutrients.

Fish as a source of foodFish as a source of food

Fish is a highly recommended food Fish is a highly recommended food item for any balanced diet because it item for any balanced diet because it is protein rich.is protein rich.

However, the amount of fish However, the amount of fish consumed depends on where you are consumed depends on where you are in the world (see page 198 fig. 12.2)in the world (see page 198 fig. 12.2)

PlanktonPlanktonThe foundation of the marine food The foundation of the marine food

chainchain Microscopic Microscopic

plant and plant and animal animal organisms organisms that drift that drift passively in passively in the ocean. the ocean.

PhytoplanktonPhytoplankton

Phytoplankton are responsible for Phytoplankton are responsible for making up to 90% of Earth's oxygen. making up to 90% of Earth's oxygen.

Phyto = "Light" Phyto = "Light" Plankton = "Floating/Suspended"Plankton = "Floating/Suspended"

PhytoplanktonPhytoplankton

Requires sunlight, suitable water Requires sunlight, suitable water temperatures, and specific nutrients.temperatures, and specific nutrients.

These requirements are best met on These requirements are best met on the shallow waters over the the shallow waters over the continental shelves.continental shelves.

The shallowness of water benefit The shallowness of water benefit phytoplankton in two waysphytoplankton in two ways

1.1. It guarantees an adequate amount It guarantees an adequate amount of sunlight. Sunlight can penetrate of sunlight. Sunlight can penetrate through water to a depth of about through water to a depth of about 90 m.90 m.

2.2. Shallow waters are characterized by Shallow waters are characterized by an effective system of circulation. an effective system of circulation. Currents and upwellings churn up Currents and upwellings churn up the contents at lower depthsthe contents at lower depths

Below the zone of sunlight , dead Below the zone of sunlight , dead plants and animals decompose and plants and animals decompose and are transformed into plant nutrients. are transformed into plant nutrients.

Effective circulation of these Effective circulation of these nutrients bring them up to the nutrients bring them up to the sunlight zone for the plankton to sunlight zone for the plankton to consume.consume.

The mixing of cold and warm water is The mixing of cold and warm water is also thought to enhance cirulation.also thought to enhance cirulation.

Because fish feed on phytoplankton, Because fish feed on phytoplankton, the worlds capture fishery tends to the worlds capture fishery tends to be concentrated in areas where be concentrated in areas where phytoplankton thrive.phytoplankton thrive.

Technology and fishing activityTechnology and fishing activityInshoreInshore

In Atlantic Canada most boats are under In Atlantic Canada most boats are under 25m in length and are owner operated.25m in length and are owner operated.

They most commonly stay within 20 They most commonly stay within 20 kms of shore.kms of shore.

Boats have a limited capacity and little Boats have a limited capacity and little refrigeration.refrigeration.

Return to port each day to off load Return to port each day to off load catch.catch.

OffshoreOffshore

More capital intensive and less More capital intensive and less labour intensive. It accounts for over labour intensive. It accounts for over 40% of the catch but only 20% of the 40% of the catch but only 20% of the workers.workers.

Vessels are large (35-45m) and are Vessels are large (35-45m) and are normally owned by large companies.normally owned by large companies.

Vessels have a large refrigeration Vessels have a large refrigeration capacitycapacity

2 categories of fish2 categories of fish

1.1. Demersal: live on or near the Demersal: live on or near the ocean floor (cod, halibut, flounder, ocean floor (cod, halibut, flounder, hake, shrimp, and shelfish)hake, shrimp, and shelfish)

2.2. Pelagic: tend to congregate in Pelagic: tend to congregate in schools near the ocean surface schools near the ocean surface (herring, anchovies, salmon, (herring, anchovies, salmon, mackerel, and tuna)mackerel, and tuna)

Gear used in demersal Gear used in demersal fisheryfishery

1.1. Otter TrawlOtter Trawl - also known as - also known as dragging.dragging.

A large net is dragged along the A large net is dragged along the bottom. Over the past several bottom. Over the past several

years years there has been a growing there has been a growing concern concern about the impact that about the impact that intensive intensive trawling and/or trawling and/or dredging activities have dredging activities have on the on the habitat on the sea bottom. habitat on the sea bottom.

http://www.fishingnj.org/diaotter.htm

2.2.Long line or baited hook Long line or baited hook - a - a commercial fishing technique that uses commercial fishing technique that uses hundreds or even thousands of baited hundreds or even thousands of baited hooks hanging from a single line. hooks hanging from a single line.

http://www.birdsaustralia.com.au/albatross/images2/bottom_big.jpg

3.3.Gill netsGill nets – Fish try to swim through – Fish try to swim through deliberately sized mesh openings in a deliberately sized mesh openings in a hanging net but are unable to squeeze hanging net but are unable to squeeze through. They are prevented from backing through. They are prevented from backing out due to the tendency for their gills to out due to the tendency for their gills to become caught. This effectively traps them. become caught. This effectively traps them.

4.4.Other Other devices devices include include fish traps fish traps for species for species such a such a crab and crab and lobster.lobster.

http://www.brassbinnacle.com/Merchant2/images-sep2003/102_0211-lg.jpg