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Resources from the Sea
Shipley Marine Biology
Summit High School
Marine Resources are
 Food
 Products
 Materials
 Recreation
Food From the Sea
 What types of organisms are harvested?
 Finfish (about 90% of worldwide harvest)
 Shellfish
 Other species such as jellyfish, sea cucumbers,
polychaetes and seaweed
 While seafood represents only about 1% of the food
consumed each year, it represents about 30% of total
animal protein consumed
The Fisheries Industry
 1950’s to present- there was a five-fold increase in
fishing effort
 1980’s to present- worldwide catches relatively
constant despite the increased fishing effort
 Many of world’s most important catches are
overexploited or exhausted (especially in the Atlantic,
Pacific and Mediterranean)
Worldwide Commercial
Worldwide Marine Catch
and Mariculture
Major Fishing Areas
 Most located near coast over continental shelf
 Easier to catch demersal species
 High primary production in these areas means more
species are present
 Ex: Grand Banks of Newfoundland, North Sea and
Bering Sea
Examples of
Commercially Important
 the World
Fishes Around
Major Food Species
 Clupeoid fishes
 Sardines, menhaden, shad and herrings
 How they are used:
 Eaten directly
 Fish flour (powder used as a dietary supplement
 Fish meal (ground fish used as protein
supplement for poultry, livestock and
 Fish oil (used in manufacture of margarine,
cosmetics, paints, omega-3 fatty acids
Major Food Species
 Cods, haddock, hakes, pollock, whiting
 Demersal, cold water species
 Has been harvested for centuries
 Sold fresh and frozen
 Vital source of inexpensive protein in many parts of
the world
Cod Fishery of the Grand
 Fishery peaked in the 1960’s then began to decline
 Moratorium declared in 1992 to attempt to save the
 Closure caused high unemployment in American and
Canadian fishermen
 The fishery may never recover
 The cod is listed as endangered in that area even
Major Food Species
 Jacks, Mullets, Rockfishes and Mackerels
 Important in worldwide tonnage
 Cheap protein in some parts of the world
 In the United States, flounders and other flatfish are
 Salmon also remain important catch
Major Food Species
 Tuna
Caught in open water
These fish command high prices
They are caught on long lines or in gillnets
Fishing boats are equipped with freezers so they can
stay at sea longer
280 lb
120 lb. Swordfish
This is a Cobia
Golden Tile Fish
Major Food Species
 Molluscs
 Second most valuable catch after finfish
 Squids, cuttlefish, and octopus are particularly
important in the Far East
 Clams, oysters, mussels, scallops and abalones are
important worldwide
Major Food Species
 Crustaceans
 Prized worldwide
 Command high prices
 Shrimp, lobster, crab
Other Harvested Marine
 These species contribute little to the worldwide
 Sea weeds, jellyfish and sea urchins harvested in
Far East, especially Japan
 Gooseneck barnacles are harvested in Spain
 Polychaete worms are harvested in South Pacific
 Sea turtles and their eggs are harvested and
eaten even where they are protected by law
 Seals and whales are still eaten in some cultures
despite laws to protect them
Optimal Yield and
 Sea-life species are renewable resources
 However, for a fishery to last long-term, it must be
fished in a sustainable way
 The sustainable yield is the amount that can be
caught and just maintain a constant population size
 Maximum sustainable yield is the highest catch that
can be maintained year after year without affecting
the stock
Exceeding Maximum
 If catches fall despite increased fishing effort,
overfishing has occurred
 Market forces often cause this to happen
 If other fishermen are making money, other
fishermen will be attracted to the fishery and cause
overfishing to occur
Exceeding Maximum
 It is estimated that about 70% of marine fishes
are overfished
 This is especially true for large species like tuna,
swordfish and sharks
 In many of these species, the fish that are
harvested today are about half the size of those
harvested 20 years ago
 Ex: Bigeye tuna were two times as heavy and
eight times more abundant in 1950’s than they
are today
Exceeding Maximum
 Swordfish
 Catches of these fish fell 70% between the 1960’s
and the late 1990’s
 A campaign to reduce consumption of these fish was
 Numbers of the fish are recovering
Other Dangers to
 Habitat destruction
 Critical breeding grounds like seagrass beds, estuaries
and mangroves are destroyed each year
 This is especially detrimental since 75% of
commercially important species use estuarine areas as
nursery areas
 Trawls used in fisheries also damage the ocean floor
which is detrimental to demersal species
Collapse of a Fishery
 A fishery is regarded as collapsed if numbers fall to
10% of historic highs
 It is estimated that one-third of fisheries are already
 A 2006 study indicates that all major fisheries will
collapse by 2050 if protective measure are not taken
to better manage and protect these resources
Managing the Resources
 Management can be difficult for many reasons:
 Maximum sustainable yield is difficult to calculate
 Harvested species may compete with other species
and fishing pressure may affect competitive balance
 Real fisheries are more complex than models
 High seas are “common property”
Ways to Manage a
 Limiting total catch and closing the fishery when the catch
is reached
 Limiting length of fishing season
 Limiting areas open for fishing (to include marine
 Limiting number of boats permitted to fish
 Limiting gear size or gear type
 Limiting size of fish caught
 Limiting catches per boat
 Limiting fishing methods
United StatesSustainable
Fisheries Act
 Passed in 1996
 Requires federal fisheries managers to develop
plans to avoid overfishing, restore depleted
stocks and reduce by-catch (species caught
incidentally while fishing for a target species)
 US fishermen must abide by rules as well as
foreign fishermen with valid permits
 In 2003, the Pews Ocean Commission calls for
management of ecosystems as well
New Fisheries
 New fisheries may be available by increasing the
use of by-catch
 However, consumer tastes are fickle and these
species may not be appealing to consumers
 Some species may be able to be used in the
manufacture of imitation crab (as pollocks are
 Other untapped potential fisheries – squid, flying
fish and lanternfish
Mariculture and
 Aquaculture is the application of farming techniques
to the growth and harvesting of aquatic organisms
 The term mariculture applies specifically to marine
 The column of marine organisms produced through
mariculture has risen three-fold since 1990
 As an example, farmed fish account for 25% of
shrimp consumed each year
 Other “farmed” species include milkfish, molluscs,
seaweed, salmon and Pacific threadfish
Commercial Mariculture
Problems Associated
 Disease and parasites can be high due to many organisms in
close proximity
 Different food requirements may be present at different life
 Species that require open water cannot be raised this way
 Maintaining water quality may be difficult
 If farmed species escape, they may breed with wild stocks and
dilute genome of wild population
 Pollution from farm ponds can leak into nearby waters
 In some areas of the world, mangroves and other estuarine
communities are destroyed to create farm ponds
Marine Life as Items of
Commerce and
 Other items harvested for reasons other than direct
 Mangroves – for timber and charcoal
 Pearls, shells, coral and sea turtle shells for jewelry
 Some species harvested for their chemical compounds
that are used as “marine natural products”
Marine Life as Items of
Commerce and
 Amateur anglers – in general, marine resources
caught by recreational anglers is only about 30% of
the amount caught by commercial fishermen
 However, for some species, the number of individuals
caught each year may be solely from recreational
 Other species are harvested each year for the
aquarium trade
Non-Living Resources
Harvested from the
Marine Environment
 Oil and Gas
 Sand and gravel for the construction industry
 Freshwater via desalination process
Non-Living Resources
Harvested from the
Marine Environment
 NaCl
Non-Living Resources
Harvested from the
Marine Environment
 Tidal energy
Non-Living Resources
Harvested from the
 Polymetallic nodules – contain manganese, nickel,
copper and cobalt