1. Chapter 17 Lecture Slides
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

2. Chapter 17
Resources from the Sea

3. Marine Resources are Utilized For:
Food
Products
Materials
Recreation

4. 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

6. 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)

7. Worldwide Commercial Catches

8. Worldwide Marine Catch and Mariculture

9. 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

11. Examples of Commercially Important Fishes Around the World

12. Major Food Species Clupeoid fishes How they are used:
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 aquaculture
Fish oil (used in manufacture of margarine, cosmetics, paints, omega-3 fatty acids

13. 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

14. Cod Fishery of the Grand Banks
Fishery peaked in the 1960’s then began to decline
Moratorium declared in 1992 to attempt to save the fishery
Closure caused high unemployment in American and Canadian fishermen
The fishery may never recover
The cod is listed as endangered in that area even today

15. 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 important
Salmon also remain important catch

16. 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

17. 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

18. Major Food Species Crustaceans Prized worldwide Command high prices
Shrimp, lobster, crab

19. Other Harvested Marine Life
These species contribute little to the worldwide catch
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

20. Optimal Yield and Overfishing
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

21. Exceeding Maximum Sustainable Yield
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

22. Exceeding Maximum Sustainable Yield
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

23. Exceeding Maximum Sustainable Yield
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 successful
Numbers of the fish are recovering

24. Other Dangers to Fisheries
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

25. 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 collapsed
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

26. 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”

27. Ways to Manage a Fishery
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 reserves)
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

28. United States- Sustainable 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

29. 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 currently)
Other untapped potential fisheries – squid, flying fish and lanternfish

30. Mariculture and Aquaculture
Aquaculture is the application of farming techniques to the growth and harvesting of aquatic organisms
The term mariculture applies specifically to marine organisms
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

32. Commercial Mariculture Species

33. Problems Associated with Aquaculture/Mariculture
Disease and parasites can be high due to many organisms in close proximity
Different food requirements may be present at different life stages
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

34. Marine Life as Items of Commerce and Recreation
Other items harvested for reasons other than direct consumption:
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”

35. Marine Life as Items of Commerce and Recreation
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 anglers
Other species are harvested each year for the aquarium trade

36. Non-Living Resources Harvested from the Marine Environment
Oil and Gas
Sand and gravel for the construction industry
Freshwater via desalination process

37. Non-Living Resources Harvested from the Marine Environment
NaCl

38. Non-Living Resources Harvested from the Marine Environment
Tidal energy

39. Non-Living Resources Harvested from the Marine Environment
Polymetallic nodules – contain manganese, nickel, copper and cobalt