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Marine Resources are Utilized For: Marine resources • • • • 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 Worldwide Commercial Catches • 1950’ 1950’s to presentpresent- there was a fivefive-fold increase in fishing effort • 1980’ 1980’s to presentpresent- worldwide catches relatively constant despite the increased fishing effort • Many of world’ world’s most important catches are overexploited or exhausted (especially in the Atlantic, Pacific and Mediterranean) 1 Major Fishing Areas Worldwide Marine Catch and Mariculture • 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 Fishes Around the World Optimal Yield and Overfishing • SeaSea-life species are renewable resources • However, for a fishery to last longlong-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 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’ 1950’s than they are today 2 Exceeding Maximum Sustainable Yield • Swordfish • Catches of these fish fell 70% between the 1960’ 1960’s and the late 1990’ 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 oneone-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 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 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” property” United StatesStates- Sustainable Fisheries Act • Passed in 1996 • Requires federal fisheries managers to develop plans to avoid overfishing, restore depleted stocks and reduce byby-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 3 New Fisheries Mariculture and Aquaculture • New fisheries may be available by increasing the use of byby-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 • 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 threethree-fold since 1990 • As an example, farmed fish account for 25% of shrimp consumed each year • Other “farmed” farmed” species include milkfish, molluscs, seaweed, salmon and Pacific threadfish Commercial Mariculture Species Geoduck farming • • • Mussel farming plants geoduck “seed” at a higher density than what occurs in nature. predator protection devices (pvc tubes or netting) around small geoduck “seed” when they are most vulnerable to predation by shrimp, crabs, flatfish, and sea stars (in the first 6 to 18 months after planting). A crop of geoducks may take 6-8 years to reach market size. After harvest, an intertidal area under an aquatic farmers control may be re-planted with geoduck seed to begin a new crop. 4 Oyster farming Salmon net pen farming • Problems: – Escapes – Sedimentation – Genetically modified Problems Associated with Aquaculture/Mariculture 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 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 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 NonNon-Living Resources Harvested from the Marine Environment • NaCl NonNon-Living Resources Harvested from the Marine Environment • Oil and Gas • Sand and gravel for the construction industry • Freshwater via desalination process NonNon-Living Resources Harvested from the Marine Environment • Tidal energy 5