Commercial fishing:• 500 species regularly caught• Employs 200 million people worldwide• In 2002 the world fishing fleet numbered

about four million vessels. In 2005:• 100 million tons taken• $70 billion

Global Fish Catch

Emptying the oceans• We are placing unprecedented pressure on

marine resources- Half the world’s marine fish populations are fully

exploited- 25% of fish population are overexploited and

heading to extinction

• Total fisheries catch leveled off after 1998, despite increased fishing effort- It is predicted that populations of all ocean species

we fish for today will collapse by the year 2048

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Fish Population Estimates

We have long overfished

• People began depleting sea life centuries ago

• Some species hunted to extinction: Steller’s sea cow, Atlantic gray whale, Caribbean monk seal

• Overharvesting of Chesapeake Bay oyster beds led to the collapse of its fishery, eutrophication, and hypoxia

• Decreased sea turtle populations causes overgrowth of sea grass and can cause sea grass wasting disease

• People never imagined that groundfish could be depleted

- New approaches or technologies increased catch rates

Fishing Techniques

Fishing Methods • Harpoon - whales, swordfish, bluefin tuna • Pole and line - mahi-mahi and used for tuna

extensively in the 50‘s • Longline - swordfish, tuna (pelagic); cod,

halibut (bottom) • Trolling - salmon, albacore, mahi-mahi • Drift (gill) netting - various pelagic fish • Trawl - anchovies (pelagic); cod, halibut

(bottom) • Purse seine - sardines, herring, mackerel • Traps and Pots - Crabs, lobster, rock fish

Gillnetting

net size: 20 m x 65 km

Uses curtains of netting suspended by a system of floats and weights

Either anchored to sea floor or float at the sea surface

Netting is almost invisible, fish swim right into it; and their gills get caught

Drift Netting

•Large floating nets•Unbreakable and invisible to most sea species •likely to entangle large pelagic species:dolphins, whales, sharks, turtles, and rays.

Driftnets have earned the nickname “walls of death.”

Longlining

•Longlines are horizontal sets of fishing hooks•Set on the ocean floor: demersal longlines•Set near the surface: pelagic longlines•Longlines can be tens of kilometres long•Can carry thousands of hooks •Baited hooks are attached to the longline by short lines called snoods that hang off the mainline.

•Not anchored; set to drift near the surface of the ocean •Attached radio beacon tracks line to haul in catch•Usually used to catch large tuna and billfish species.

•Anchored to the sea floor. •Buoys mark line•Same as Pelagic longline in all other respects

Purse seine

Animation

•Uses large wall of netting to encircle schools of fish•Drawstring pulls bottom of netting closed, like a purse•Herds schools of fish into center•Some purse seines can unintentionally catch other animals (dolphin caught when fishing for tuna)

Trawl

midwater

bottom

http://www.youtube.com/watch?v=bUHcD_jTgVA

Effects of Trawling on Coral Reefs

http://www.eea.europa.eu/publications/report_2002_0524_154909/regional-seas-around-europe/page111.html

Trawl from space

Gulf of Mexico, near Louisiana coast. Individual vessels can be seen as bright spots at end of sediment trails. Other bright spots are fixed oil and gas production platforms. One sediment trail can be traced for 27 km. Assuming a standard trawling speed of 2.5 knots, sediment from this trawl is visibly persistent for nearly 6 hours. Water depth <20m. Large, indistinct bright blue patches at lower left and upper right are cloud/haze. (Credit: Landsat)

Sonar

• Uses sound waves that allow fishermen to quickly locate fish and/or see the bottom

• Targets specific speciesImage: http://www.marinesonic.com

Courtesy of Wikipedia CommonsFactory Ship

•Can haul in LARGE quantities of fish•Can process and freeze fish onboard•Up to 60 - 70 meters long•Can be at sea for six weeks at a time with a crew of over 35 people.

Types: demersal (weighted bottom trawling)-pelagic (mid-water trawling) - pair trawling, two vessels, 500 metres apart, both pull huge net with a mouth circumference of 900 meters

Pole / Troll

•Uses fishing pole and bait to target fish

•Environmentally responsible; alternative to longlining

•pole/troll fishermen have very low bycatch rates.

Fisheries mismanagement• Overfishing• Commercial extinction• Bycatch (27 million metric tons annually)• Targeting smaller species on the low end of

the food chain

Fisheries Problems & Solutions A. Maximum sustainable yield: maximum amount of

fish that can be harvested without depleting future stocks

B. World‘s maximum sustainable yield estimated at 100 to 135 million metric tons

C. Present harvests are at about 100 million metric tons

D. For fisheries where numbers available, estimated that 45% are currently over-fished

E. A number of fisheries have already collapsed (Anchovy fishery off Peru, Cod fishery in the N. Atlantic)

Fisheries Problems & Solutions F. Bycatch (or bykill): animals unintentionally killed during

harvest of the target species Trawling: Bycatch in shrimp trawling is very high (125 to 830% of the catch is discarded as bycatch), turtles often caught in trawls. SOLUTION: trawls with trap doors to let turtles escape

•Allows smaller fish to be caught•Allows turtles to escape•Lowers incidence of bycatch

•Same concept as TEDs•Hatch kept open with inflatables

Modern fishing fleets deplete marine life rapidly

• Grand Banks cod have been fished for centuries• Catches more than doubled with immense industrial

trawlers- Record-high catches lasted only 10 years

Bycatch by Gear Type for 2002/2003

Dolphins caught in tuna net

Purse seine: Tuna known to hang out under pods of dolphins, nets set around pods of dolphins would result in many drowning.

SOLUTIONS: Nets not set around dolphin pods and/or employ — “backing down”, a technique that lowers upper edge of net letting dolphins escape

Fisheries Problems & Solutions

Driftnets: indiscriminate entangling of many sorts of marine animals SOLUTION: banned in oceanic fisheries (but some countries still using them)

Fisheries Problems & Solutions Long lining: Many albatross drown trying to snatch bait from long lines being deployed. snagged on hooks and pulled under. SOLUTION: deploy in the dark or with special rig to let line out under water.

Global swordfish catch

http://www.pifsc.noaa.gov/wpacfin/hi/dar/Pages/hi_fish_2.php

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Artificial ReefsImprove the local marine bio-density

1. attract schools of fish 2. providing habitats for the colonization

of commercially valuable species3. improve the local inshore marine

harvest

May wash up on beaches

tires ship wrecks construction rubble

Aquaculture (marine agriculture)- farming finfish, shellfish and algae under favorable conditions

One of every four fish eaten today was raised in either a fw or sw fish farm.

Aquaculture also produces:• Bait fish• Ornamental or aquarium fish• Aquatic animals used to augment

natural populations• Algae for chemical extraction• Pearl oysters

History:

• 2000 years ago in Egypt, Rome, China• <2000 years in Hawaii• 600 years ago France developed mussel

aquaculture• 500 years ago Europe developed the idea of

using pond fertilizer to promote plankton growth

• 400 years ago China discovered that oysters would grow on bamboo stakes

• 1960’s- Europe and U.S. catfish and salmon

Criteria for selecting species for farming:

- inexpensive to grow

- grows quickly

- high sales price

- resistant to disease and parasites

Hawaii open ocean aquaculture

Mio, big eye tuna, yellow tail

$34.7 million in 2008

Industrialized fishing depletes populations

• Catch rates drop precipitously with industrialized fishing

- 90% of large-bodied fish and sharks are eliminated within 10 years

- Populations stabilize at 10% of their former levels

• Marine communities may have been very different before industrial fishing

- Removing animals at higher trophic levels allows prey to proliferate and change communities

Several factors mask declines

• Industrialized fishing has depleted stocks, global catch has remained stable for the past 20 years

- Fishing fleets travel longer distances to reach less-fished portions of the ocean

- Fleets spend more time fishing and have been setting out more nets and lines, increasing effort to catch the same number of fish

- Improved technologies: faster ships, sonar mapping, satellite navigation, thermal sensing, aerial spotting

- Data supplied to international monitoring agencies may be false

We are “fishing down the food chain”

• Figures on total global catch do not relate the species, age, and size of fish harvested

• As fishing increases, the size and age of fish caught decline

- 10-year-old cod, once common, are now rare

• As species become too rare to fish, fleets target other species

- Shifting from large, desirable species to smaller, less desirable ones

- Entails catching species at lower trophic levels

Consumer choices influence fishing practices

• Buy ecolabeled seafood

- Dolphin-safe tuna

• Consumers don’t know how their seafood was caught

- Nonprofit organizations have devised guides for consumers

- Best choices: farmed catfish and caviar, sardines, Canadian snow crab

- Avoid: Atlantic cod, wild-caught caviar, sharks, farmed salmon

The Big Question

• Fish Populations are declining

• The Human Population is increasing exponentially

• What can be done to sustain fish as a viable food resource for the human population?

• What YOU can do: Choose to eat sustainably harvested seafood

Highly efficient

High yield in smallvolume of water

Increased yieldsthrough cross-breeding and genetic engineering

Can reduce over-harvesting of conventional fisheries

Little use of fuel

Profit not tied to price of oil

High profits

Advantages

Large inputs of land, feed, And water needed

Produces large and concentrated outputs of waste

Destroys mangrove forests

Increased grain productionneeded to feed some species

Fish can be killed by pesticide runoff from nearby cropland

Dense populations vulnerable to disease

Tanks too contaminated touse after about 5 years

Disadvantages

Trade-Offs

Aquaculture

Aquaculture Methods

Is Aquaculturethe Answer?

• Reduce use of fishmeal as a feed to reduce depletion of other fish

• Improve pollution management of aquaculture wastes

• Reduce escape of aquaculture species into the wild

• Restrict location of fish farms to reduce loss of mangrove forests and other threatened areas

• Farm some aquaculture species (such as salmon and cobia) in deeply submerged cages to protect them from wave action and predators and allow dilution of wastes into the ocean

• Set up a system for certifying sustainable forms of aquaculture

Solutions

More Sustainable Aquaculture

Relevant Laws

• UN Law of the Seas

• Magnuson-Stevens Fisheries Management and Conservation Act (Magnuson Act)

• Marine Sanctuaries Act

• Oceans Act of 2000

• Endangered Species Act (ESA)

• Convention on International Trade in Endangered Species (CITES)

• Lacey Act of 1900

Laws Related to Fishery Management

• UN Law of the Seas

- Nations have jurisdiction over Exclusive Economic Zones (200 Miles)

- Sea Floor sovereignty up to 12 miles offshore

- Allows for Individual Transferable Quotas which

can be sold to others

• Magnuson Act

- Establishes 200 mile fishing area

- Set up regional councils that

- Set quotas

- Set size limits

- Set seasons

- Protects habitat

- Minimizes bycatch

- Rebuilds overfished stocks

Fisheries management• Based on maximum sustained yield

- Maximal harvest while keeping fish available for the future

- Managers may limit the harvested or restrict gear used

• Despite management, stocks have plummeted

- It is time to rethink fisheries management

• Ecosystem-based management

- Shift away from species and toward the larger ecosystem

- Consider the impacts of fishing on habitat and species interactions

- Set aside areas of oceans free from human interference

We can protect areas in the ocean

• Marine protected areas (MPAs) = established along the coastlines of developed countries- Still allow fishing or other extractive activities

• Marine reserves = areas where fishing is prohibited- Leave ecosystems intact, without human interference- Improve fisheries, because young fish will disperse into

surrounding areas

• Many commercial, recreation fishers, and businesses do not support reserves

Reserves work for both fish and fisheries

• Found that reserves do work as win-win solutions

• Overall benefits included…

- Boosting fish biomass

- Boosting total catch

- Increasing fish size

• Benefits inside reserve boundaries included…

- Rapid and long-term increases in marine organisms

- Decrease mortality and habitat destruction

- Lessen the likelihood of extirpation of species

Areas outside reserves also benefit• Benefits included…

- A “spillover effect” when individuals of protected species spread outside reserves

- Larvae of species protected within reserves “seed the seas” outside reserves

- Improved fishing and ecotourism

How should reserves be designed?

• 20-50% of the ocean should be protected in no-take reserves - How large?

- How many?

- Where?

• Involving fishers is crucial to fisheries to determine the answers

Laws Related to Habitat Protection

• Marine Sanctuaries Act

- Protects habitat of marine organisms

- Protects animals from being harvested in that area

• Oceans Act of 2000- Established Presidential

Commission to

- Examine Federal Ocean Policy

- Promote protection of marine environments

- Prevent marine pollution

Laws Related to Species Protection

• ESA

- Identifies and lists endangered species

- Prohibits the harm or harvesting of listed species

- Protects habitat

• CITES

- Identifies and lists endangered species

- Prohibits international trade in listed species

• Lacey Act of 1900

- Prohibits sale of illegally harvested species

- Forces legal methods

Conclusion

• Oceans cover most of our planet and contain diverse topography and ecosystems

• We are learning about the oceans and coastal environments, intensifying our use of their resources, and causing severe impacts

• Setting aside protected areas of the ocean can serve to maintain natural systems and enhance fisheries

• We may once again attain the ecological systems that once flourished in our waters

QUESTION: Review

• Which of the following does not mask the decline of fisheries?

– Fishing fleets travel longer distances– Fishing fleets spend more time fishing– Fishing fleets use traditional methods of fishing– Data supplied to monitoring agencies may be false

QUESTION: Review

• Marine reserves have all the following benefits except:

– Fishing increases in the reserve– The size of fish increases– Larvae can “seed” areas outside the reserve– Decreased mortality and habitat destruction

QUESTION: Interpreting Graphs and Data

•What does this graph show about the future of global fisheries catch?

a) China will be a major player in applying fishing pressure

b) China will be playing a smaller role in applying fishing pressure

c) The world will decrease its fishing pressure

d) The U.S. is not included in this graph

QUESTION: Interpreting Graphs and Data

• Which conclusion can you draw from this graph?

a) Oceans today contain far fewer fish

b) Oceans today contain far more fish

c) It is easier to find fish todayd) There is little correlation

between fishing and fish stocks

QUESTION: Viewpoints• If a developer wants to build a community on an estuary,

providing jobs but eliminating the marsh, what should be done?

– Let the developer build; we need the jobs– Let the developer build, but make him/her pay for any

damage from storms– Let the surrounding landowners vote whether to let

the developer build– Prevent the development; the potential damage is

too great

QUESTION: Viewpoints

• Do you plan to alter your decisions about eating seafood?

– Yes; I will be more selective about what I eat– No; I will continue to eat the same type and amount of

seafood as always