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Resources from the Sea Shipley Marine Biology Summit High School Marine Resources are Utilized For: 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 Catches 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 aquaculture 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 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 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 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 Bigeye tuna 120 lb. Swordfish Wahoo 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 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 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 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 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 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 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 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 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 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 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 currently) Other untapped potential fisheries – squid, flying fish and lanternfish 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 Commercial Mariculture Species 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 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” 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 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 Marine Environment Polymetallic nodules – contain manganese, nickel, copper and cobalt
