Methods, Pro’s and Con’s

History• Fish are a vital component of the human diet -

nearly half the world’s population gets the majority of its protein from seafood

• As population increases, so does demand for seafood…

• But Many species - perhaps 70% or more - have been fished to their sustainable limits or beyond.

• Fish stocks are declining

Why are our fish stocks declining?• Overfishing:

– Bigger fishing vessels

– Better technology to find fish

– Better nets– Higher

demand– Lag time in

population drop FAO State of World Fisheries and Aquaculture (SOFIA) – 2006

http://www.fao.org/DOCREP/007/y5600e/y5600e00.htm

Question

What do we do?

The answer: Aquaculture?• Proponents of fish farming say that the

industry not only supplies an important food resource, it also benefits wild stocks by reducing fishing pressures.

• However, Many fishermen and environmentalists disagree– claim that aquaculture can degrade the

habitat, health, and genetic vigor of wild species

Salmon DebateFarm-raised Salmon Wild Salmon

Survival rate from egg to adult of 80-90%

Concentrated waste cause algal blooms and low oxygen ‘dead zones’

Higher levels of pollutants in tissues

Less expensive and more widely available to consumers

Color from dyes, feed antibiotics, fewer essential fatty acids and oils

Survival rate from egg to adult of 1-2%

Declining wild populations due to overfishing and habitat degradation

Live and dead fish important part of stream and ocean food chains

Seabirds and marine mammals caught and killed during fishing activities

No dyes, no antibitoics, healthier

Open net pens or cages• Anchored in offshore

coastal areas– Salmon, tuna

• Pro’s: – Cheap– no by-catch– does not deplete wild stocks

• Con’s:– Waste passes to

environment– Escapees– Disease & parasites

http://www.ambhanoi.um.dk/NR/rdonlyres/92ADABED-4F6A-4F6A-A04D-2A83242C1687/0/aquaculture3.jpg

Ponds • Manmade ponds, recirculating seawater

– Shrimp, catfish, tilapia• Pro’s:

– Cheap– no by-catch– does not deplete wild stocks– Provides jobs

• Con’s:– Location of ponds can destroy

important habitat (mangroves)

– Untreated water contaminates local environment • But, it CAN be treated

http://www.biology.duke.edu/bio217/2005/ncm3/pond_liner.gif

Raceways• Divert water from a

waterway– Must be treated before

being released back to waterway

– Rainbow trout• Pro’s:

– no by-catch– does not deplete wild

stocks– Provides jobs

• Con’s:– Can be costly to build– Untreated water– Escapees (invasive species)

http://www.lib.noaa.gov/korea/korean_aquaculture/raceway.files/baqbk001.jpeg

Recirculating Systems• Enclosed tanks

– Water is cleaned & reused– Striped bass, salmon,

sturgeon– Environmentally sound

• Pro’s– Can help rebuild wild

populations– Provides jobs– Conserves wild stocks

• Con’s– Requires a lot of energy

and thus $$

http://www.ag.auburn.edu/fish/image_gallery/data/media/77/Recirc_Kent_Seatech_jpg.jpg

Shellfish Culture• Ropes, plastic trays,

mesh bags– Shellfish require only

clean water to survive

• Pro’s– Easy to do– Can clean up nutrient

rich water– Protects wild

populations

• Problems:– Waste accumulation– disease

http://www.whoi.edu/cms/images/oceanus/2005/6/v43n1-kitepowell3en_10837.jpg

Why should we bother?FoodLong term

economicsOverfishing

correlates with:Low biodiversity in

the environmentHarmful algal

bloomsBeach closures

Darker color = more protein obtained from seafood

Why should we bother?While some recover

after collapse, many do not (or at least, have not)CodAtlantic Bluefin tunaPacific Northwest

Salmon

There used to be wars over Atlantic cod, now they are almost gone….

http://www.codgen.olsvik.info/cDNA%20libraries.html

Seafood Choices

http://www.edf.org/page.cfm?tagID=16150

Issue: Imported FishThe seafood Americans eat largely comes

from abroad

Problem: many nations that supply us with farmed fish do not adequately regulate these operations

Solution: policymakers and fish farmers worldwide need to implement strong standards for aquaculture operations

Issue: Economic and ecological damageSome fish farming does economic and

ecological damage in the long runexample, in Thailand, Ecuador and many other

tropical nations, coastal forests of mangroves were cut down in the past and replaced with shrimp farms. Water degrades and farm closes: no farm OR mangrove

Problem: unregulated aquaculture can destroy ecological and human communities

Solution: responsible aquaculture

Issue: Water PollutionProblem: Some production systems allow

uneaten food, fish waste and drugs and chemicals to pass into surrounding waters, where they can harm ecosystems and impair water quality

Solution: Use closed recirculating systems Grow more than one species (mussels raised on

ropes suspended in the ocean can help cleanse waters polluted by salmon raised in net pens.

Minimize use of antibiotics and anti-parasite drugs

Issue: Depleting wild fish stocksProblem: Deplete food resources for wild cousins of

farmed fish Farming predatory fish like salmon can use huge

amounts of small, oily wild fish like anchovies, menhaden, mackerel and herring, leaving no food for wild fish

~1/3 of the current annual catch has been used for animal feed

Solution:Farm vegetarian or semi-vegetarian fish such as tilapia

and catfish or filter-feeders like mussels or clamsFeed predatory fish a semi-vegetarian diet supplemented

with fish byproducts

Issue: Invasive SpeciesProblem: Escaped farmed fish can pose serious

threats to wild fish populations by competing with them for food and habitat and transmitting disease and parasites

Solution:Farm species native to the region to reduce the

potential harm from introducing a new fish species.Use closed systems like tanks, rather than "leaky"

net pens or cages, to prevent escapes.Mark fish and require public reporting of escapes, to

identify culpable suppliers.

Issue: Endangering Sea AnimalsProblem: To keep them from feeding on

captive fish, wildlife such as seals, sea lions and birds are often harassed with firecrackers or loud underwater speakers that can cause disorientation, pain or hearing loss.

Solution:Site farms far from places where marine

mammals live or hunt, or birds congregate.  Use tight nets to prevent access by predators

to ponds, tanks, and net cages.