LECTURE NOTES
MARINE BIOLOGY (MARSC 180)
L. SNYDER
Ch. 13 Harvesting Living Marine Resources
•Human Population (2006):
•1850: 1 Billion
~ 6.5 Billion
Marine Species in Food Supply
•18% total animal protein from ocean
•Fishing: big business (worldwide):
–15 million employed
–$80 billion (2000), $90 billion (2001)
•90% taken from continental shelf neritic water
•10% bottom fish& invertebrates
Seafood Sources
•Most are harvested animals 3 or 4 trophic levels above primary producers
–Few farmed, most wild stocks
•Comparison to terrestrial species:
•On land, more plants are harvested than animals
–Most farmed, few wild sources
Seafood caught for Direct human consumption, fish meal for livestock, poultry, farmed fish
Renewable Resources?
Fishing fleets
•75% of harvest by huge commercial fleets
•Work year-round
•Scouting vessels locate fish
•Factory ships follow fleet
•Process, can, freeze at sea
•Commercial Fishing Technology
•1950-1997: Marine catch  > 5X
•Due to fishing gear technology
•Satellite Technology: Tracks plankton blooms, fish schools
HUGE Nets:
•Purse seine
•Trawls
•Hold up to12 747 airplanes
Bycatch
•Animals unintentionally killed while collecting desirable species
–Young & low-value fish, seabirds, mammals, turtles
•~30 million tons sea life each year
•2002 fish discards: twice desired commercial & recreational catch
•Shrimp trawlers: 10 lbs. bycatch per lb. of shrimp
•Bottom trawling: most damaging
Bycatch solutions
•Modify gear: change net's mesh size & shape  young escape
•Purse seines w/ acoustic alarms
•Longline fishing: Night-setting, Lines w/ metallic streamers (scare birds), weights (sink)
•Reduce or Limit fishing: Economically extinct spp.
•Marine reserve network: protect breeding & nursery grounds
Problem of Overexploitation
•Maximum sustainable yield:
Maximum amount of a population that can be harvested without
impairing future populations
•Estimate: 110-135 million metric tons
–2001: 130.2 MMT
•We’re at limit or have exceeded it
–Reflected in reduced catches despite  effort
Exceeding Maximum Sustainable Yield
•Properly managed fisheries can be renewable resources
•Despite  effort, yield has  since 1980’s
•~70% of marine fisheries are out-fished or overfished
•Not enough breeders left to replenish species
•$ (not science) drives industry
•Georges Bank Cod Fishery (NW Atlantic Cod)
•North Atlantic (Maine)
•Landings  ~91% from 1990-1999
•Industry response:  technology & # of boats
•Regulations:
•Daily catch limits
• Minimum size requirements
• Trawl mesh size
•Permit restrictions
•Rolling area closures
Other Mismanaged Fisheries
•Orange Roughy (New Zealand)
•1980’s “favorite fish”
•25-30 yrs. to sexually mature
•Commercially extinct in 13 years (so few left = not profitable to catch)
•Chilean Seabass (Toothfish)
•High Demand causing severe overfishing
•Unless demand , it may be commercially extinct in 5 yrs.
•A large percentage are caught illegally
Consumer Choices
•You, the consumer, have an impact on the health & survival of marine species
•Choose well-managed, harvested & farmed species
•Monterey Bay Aquarium’s Seafood Watch: www.mbayaq.org/cr/seafoodwatch.asp
Tragedy of the Commons
•G. Hardin (1968):
unrestricted access to a resource ultimately dooms the resource to over-
exploitation
–Benefits go to individuals, while costs are distributed among all
•Short-term profits of overfishing only go to those who catch the fish
–BUT, we all share the cost of overfishing
•Situation best rewards those who most heavily exploit & abuse marine resources
–At all of our expense
World Exclusive Economic Zones
•Sanctioned by United Nations LOS Treaty
•Most fishing resources are outside of national jurisdictions = all nation can equally exploit
International Law of the Sea (1982)
•148 nations signed (Jan. 2005), not U.S.A.
•Territorial Waters: jurisdiction 12 mi. from shore
•Exclusive Economic Zone (EEZ): Nations sovereign over resources & economic activities 200
mi. from shore
•High Seas: Outside EEZ’s, world shares common property
•Scientific research freedom
•Protection of sea & wildlife, prevent pollution
Is Aquaculture the Answer?
•Farming aquatic species (fresh primarily)
•Mariculture: farming of marine organisms
•20% of marine food production
–Estuaries, bays, nearshore
–$150 million/yr. ( 8% annually)
–Salmon, oysters, shrimp tuna
•Ranching: juveniles grown in pens, released to ocean, return to birthplace to spawn (caught)
–Salmon (limited success), tuna (poor)
Shellfish: Oyster, clams, mussels
•Suspended in seawater by rope, plastic trays, or mesh bags
•Filter feeders: require clean H2O
•Supplemental feed not needed
 Produces little waste
Fish:
•Enclosed in open net pens or cages nearshore
•Water & waste pass freely into surrounding habitat
•Fish often escape
Mariculture Impacts
•Ocean net pens & ponds:
–Produce tons of waste = pollution (~small city)
–Diseases & parasites spread among fish in crowded pens & to wild fish
–Antibiotics to control (prevent?!) disease leak into ocean  create drug-resistant bacteria
–Escape pens: take over habitat from wild fish, interbreed (genetically modified)
•Depleting wild stocks of smaller fish
–Carnivore fish (salmon, tuna): 2-5 lbs. of wild fish = 1 lb. of farmed salmon
•Tropical habitat destruction:
•Mangrove forests cut down for shrimp farms
•In a few years, salinity & wastesbuild up in farm ponds
•Farmers move to new location
Improving Mariculture
•Away from sea may be best
–Can’t escape or spread disease to wild fish
–Recirculating systems clean & filter waste water
•Tilapia, trout, catfish (now)
•Salmon & shrimp (experimental)
•Some vaccinate instead of antibiotics
•Eat lower on food chain
–Herbivore fish (tilapia, carp) don’t rely on wild marine fish
–Plant protein (soybeans) for carnivores (up to 60% soy)
Inland Ponds
•Fish in enclosed inland body of fresh or salt H2O
•Waste: contained & treated
•Recirculating systems: Fish in enclosed tanks where water is treated & recirculated through system
of filters
Raceways
•Fish enclosed in a channel system with a continuous source of flowing water
•Waste can be captured & treated
•Salmon
Best Farmed Choices: oysters, clams, mussels, tilapia, catfish, trout
Aquarium Trade (Live Specimens)
•Low-value (as food, etc.) fish, coral captured for profitable Aquarium trade
–Great $ incentive in poor developing nations (SE Asia)
–Purchased by wealthy nations (USA, Europe, Japan)
•Damaging harvesting techniques (poison)
•Often can’t survive shipping or in Aquarium
–Captive breeding/culture!
Whaling
•Hunted since 1600’s: meat, blubber, oil, bones (lamp oil, cosmetics, industrial lubricants,
fertilizer, corsets)
•1900: 4.4 million whales
•Today: ~1 million
•8 of 11 large species commercially extinct: Fin, blue, humpback, gray
International Whaling Commission:
Moratorium on Whaling (1986)
Commercial Whaling “ended” in 1987
•Japan & Norway continue whaling
•Despite IWC opposition
•Japan takes whales for “scientific purposes”
•Norway (1993) for food
1,000 minke killed per year by Japan & Norway
Whaling Industry Timeline
•1600’s: 1st major commercial whaling
•1868: Invention of explosive harpoon gun
•1900’s: Use of motorized & "factory" ships
•1930s’: Blue whale numbers  to 4%
•1946: Formation of International Whaling Commission (IWC)
•1986: Global commercial whaling moratorium
•1994: Establishment of whale sanctuary (Antarctic waters)
•Grey whale is 1st marine mammal removed from US endangered species list
• Commercially extinct: fin, sperm, sei, blue, humpback whales
Marine Mammal Protection Act (1972)
•Bans:
•Take of marine mammals in US territorial waters
•Take of marine mammals on high seas by persons (vessels) subject to U.S. jurisdiction
•Import of marine mammal products (1988)
•Significantly  dolphin "bykill" from tuna industry
•1960’s: 200,000 Dolphin drowned/year in yellowfin tuna nets
•Public outcry & consumer boycott  USA Marine Mammal Protection Act (1972)
–No Chasing or netting dolphins, nets set to release dolphins, unbiased observer
•Is “Dolphin safe” tuna (1990) still safe? New proposed regulations: chasing & encircling
dolphins o.k. in East Tropical Pacific
•Dolphin quota = 5,000/yr.
•Many fur-bearing species (Northern fur seal, N. Elephant seal, harp seal) hunted to near extinction
•Hunting quotas/bans: most recovered
•300,000-450,000 still taken/year for fur
“Never doubt that a small group of thoughtful, committed citizens can change the world.
Indeed, it's the only thing that ever has.”
-Margaret Mead
Antarctic Whale Sanctuary
•1994: IWC banned whaling in 8 million mi2 zone
•Often ignored by Norway & Japan
–Chile, Peru, N. Korea interested
•Pirate whalers catch & sell whales to Japan