A Marine Aquaculture Review in Three Acts

By Boyce Thorne Miller

NAMA’s Science Coordinator

In a minor adjustment of this 3-part blog, I have decided to
make this one about the choices we have as consumers and stewards of the marine
ecosystem relative to farmed seafood. It gives folks purchasing guidelines with
simplified justifications. This will be followed by the final blog, which will
be a more in-depth review of some of the history that lies behind the
guidelines – for braver souls who want more information.

Consumer Guidelines
for Marine Farmed Fish

So here is the first
general rule of purchasing farmed seafood, especially those frozen packages
in your supermarkets and big box stores: 
Don’t feel self-righteous about it. Don’t think you are doing anything
to save wild fish and shellfish, and don’t think your purchase is contributing
to the wellbeing of hungry people around the world or their access to seafood. There
may be a few cases in which this rule does not apply, but it is generally a
good guideline when you have no reliable information to the contrary.

Now for more specific guidelines to follow when you purchase
farmed seafood, which gnerally falls into three large categories—finfish, shellfish,
and seaweed. Since seaweed does
not have much of a market in the US, I’ll leave that for the historical perspective
in the next blog. The following recommendations are for farmed fish and
shellfish.

Finfish guidelines:

Tilapia and other farmed herbivores. Fish that feed
low on the food chain are generally a better choice because farms should not
have to use wild-caught fish to supplement their feed. However, just like
industrial agriculture, industrial fish farming often adds fishmeal to the feed
of herbivorous animals. Tilapia is no exception. And it’s almost impossible for
you, as a consumer, to know whether the Tilapia you are considering has been
fed wild fish. Demanding regulations for informative labeling would be a good
start.

Salmon and other carnivorous fish.   At the heart of the marine fish-farming
industry in the developed world is the intensive, large-scale cultivation of
predatory fish—most commonly salmon, but other fish are rapidly coming on line.   Salmon farming is highly
profitable but not environmentally sustainable, and it is unlikely that it will
ever be so since it violates so many principles of good animal husbandry and
efficient human food production: 
the animal being grown is a top predator so more protein goes in than is
produced; densities of animals are so great that they are stressed and disease
is rampant; they are grown in systems that expose wild fish and ecosystems to
the disease and wastes flowing from the fish farms; the waste is allowed to flow
out like raw sewage and may drift in concentrated masses for long distances; fish
escape from the farms by the thousands; and sea mammal predators attracted to
the farms are often killed.

So in this case, we can offer a simple guideline to fish
consumers considering these farmed carnivorous marine fish. Just Say No!  And when asked, here’s why:

·     *      Would you
farm and eat tigers? Most marine fish that are farmed are top predators
that must be fed meat, in particular other fish. It takes about 5 pounds of
feed fish to produce a pound of salmon. And that feed fish is wild caught fish
that should be feeding the wild fish of our ocean ecosytems.

·    *      Farmed
fish make wild fish sick. Fish farms harbor diseases and parasites that,
experience has proven, are passed to nearby wild populations of fish. Even when
effective drug treatments are applied so that the farmed fish are largely
uninfected, infected wild fish are increasingly turning up. Salmon is the
poster child for this disaster, and sea lice infections the most graphic
example. So when salmon farms are dense,
wild populations of salmon decline rather that prosper. So much for the
argument that aquaculture saves wild fish populations.

·     *     Open
water fish farms discharge raw sewage. Fish farms in natural waters have
virtually no constraints on the effluent of waste—fish excrement. When
developed on an industrial scale, with numerous pens in close proximity in coastal
areas, waste production is equivalent to a city but there are no requirements
for sewage treatment. Recent
research shows that the effluent is not immediately diluted because it is
flowing into water. Instead the mechanics and stratification of the water cause
the waste to remain concentrated for long distances, sometimes encountering
coastlines before it disperses.

breached salmon farm wreckage: salmon farm protest group/ marine photobank

·     *   Penned
fish often escape in huge numbers. When a fish pen is breached, thousands
or tens of thousands of fish flee into surrounding waters, where they become
part of the wild fish community. Some say, “So what? They just provide more
fish for the capture fisheries to catch!”   But it’s not that simple. Escaped fish may spread disease;
they may eat healthier wild fish; they may interbreed with wild individuals of
their own species; they may compete with other wild predatory fish for food and
with other anadromous fish (saltwater fish that migrate and breed in
fresh-water) for breeding habitat.

What’s wrong with interbreeding and thereby
adding to the populations of their wild sisters and brothers?  Wild fish populations have genetic
characteristics that have been honed through selection for their survival
advantage over long periods of evolution. Farmed fish are bred and raised under
conditions that do not demand the same rigor for survival in the wild. Consequently
repeated interbreeding over time can cause the wild populations to weaken and
become more vulnerable to harsh environmental conditions.

While large escapes are most infamous and
well documented, the constant trickle of single fish escaping–through small
breaks or commonly during transfer of fish into or out of pens–can add up to
thousands that have the same long term effects on wild populations.

Escapes from salmon farms in the Pacific
have an additional impact, caused by adding a new species (Atlantic salmon)
into the wild to compete with native Pacific salmon species.

Several other fish species are grown in factory farms
in Hawaii and commonly appear in supermarkets and other fish counters. The
“just say no” rule still applies!

Genetically engineered fish.  With farming comes the ever-present
scepter of genetic engineering, and fish are no
exception. A Massachusetts company has applied for FDA approval to market
genetically engineered salmon in the US. So far their prototype production is limited
to Canada (brood stock) and Panama (adult fish production). The scales would
increase with all the same threats of usual salmon aquaculture but the added
threat of genetic engineering in the food supply and escaping into the wild. Don’t
let the FDA approve the marketing of this fish or any other genetically altered
fish!  And demand labeling if any
genetically engineered food products are permitted on the market.

A word of caution to nutrition enthusiasts. Farmed
salmon is marketed primarily to health-conscious, prosperous people who have
been advised by the medical profession to eat plenty of fish. Salmon, because
of its ubiquitous availability as farmed fish in North America and Europe,
often spills out as a suggested choice. And no distinction is made between wild
and farmed. Yet if high amounts of omegas and high Omega 3/6 ratios are what is
desired by privileged societies and classes who can afford to think about long,
healthy lives, we should choose wild over farmed—even better, herring and
mackerel over salmon. And omega supplements should be made from algae instead
of fish (which get theirs from algae). With these changes fishmeal and fish oil
would loose their value and forage fish would be left in the sea to serve marine food chains and be fished in much smaller quantities for local fresh fish markets.

Shellfish Guidelines

farmed shrimp: Philip Chou Seaweb/marine photobank

Farmed shrimp. As you contemplate shrimp in your
supermarkets and on restaurant menus, remember these come primarily from
large-scale export shrimp aquaculture industries in tropical, often
less-developed, countries with poor regulations.  Though a few sustainable farms might be found in the US,
almost all the shrimp you find in markets will come from abroad. Wild-caught options
appear occasionally during shrimping seasons in Maine and the Gulf of Mexico,
and that can be a better bet, especially locally. But the safe and simplest
answer to farmed shrimp, is once again, to “just say no.”  Here’s why:

·   *  Shrimp farming in coastal areas that once
supported rich mangrove forests is notorious
for destroying coastal ecosystems.

·        *    Shrimp farms are associated with heavy use
of antibiotics.

·      *    Shrimp farming deprives local people of their access to coastal areas and their
resources and the farms are often known for mistreatment of workers.

·      *    Shrimp farming profits private companies,
sometimes foreign, and does not benefit
local people and their need for food.

·        *    Intensive, destructive, shrimp aquaculture feeds
the gluttonous demand for shrimp in international food and restaurant chains
and luxury food markets of the world.
It is not about feeding the hungry or those who wish to eat compatibly with
natural ecosystems.

Farmed mollusks (hard shelled).

farmed oysters:  Gerick Bergsma 2011/Marine photobank

When it comes to molluscan shellfish, there are good aquaculture choices available, so you need to be more aware of the dos and don’ts. Look
for shellfish farming done on scales and in locales that are not only good for
the seafood market, but also for the ecosystems in which they sit. But even
though shellfish farmers would all prefer that you allow them to rest on the
laurels of good shellfish farming and consider it all benign, it’s important to
know that some shellfish farming practices are harmful to ecosystems.

Typical shellfish that are farmed include a variety of
oysters, clams, mussels, scallops, and abalone. For examples of shellfish
farming at it’s worst, we need look no further that our State of Washington, where
economic power and politics
rule shellfish farm development. But Canadian and European examples abound as
well. Because shellfish farming almost always occurs in wild ecosystems near
shore, the problems may be significant and very obvious, although they are avoidable with careful regulation
and management.

The most reliable rule for these farmed shellfish is “know your farmer and farming technologies.”  If you can’t get the information you
need regarding mass marketed farmed shellfish it’s best to buy from local
farmers whose practices you can evaluate. You’re likely to get a better quality
product that way, too.

These are the potential
problems you need to watch out for:

·      *  The scale
can be too large for the ecosystem. In the Pacific Northwest coastal and estuary aquaculture, this is a
serious problem, but as the demand for aquaculture products increases, other locations around the country’s coastlines may come under siege. The development of
aquaculture is often disorganized and poorly regulated, until after damage has
been done. Offshore open ocean shellfish farms, common along the Atlantic coast
of Europe and northeastern Canada, are even more massive and associated with chemical and organic pollution and other impacts inherent to monoculture
factory farms.

·      *    Water
quality requirements may be counter productive, preventing farms from being
located in best sites. While it is essential that seafood be safe for the
consumer, shellfish farms are often most useful when they can also serve to
clean up the water of excessive phytoplankton blooms, which are not the associated with the highest water quality but may not always indicate unhealthy conditions.  In some places, potential contamination
problems can be averted by placing shellfish into clean-water lots for final
purging; or shellfish in highly contaminated locales may simply be used to
clean the water and not be marketed.  That approach can create new areas suitable for shellfish farming for food.

·      *  Bottom
habitats may be destroyed. Most shellfish farms have a footprint on
the seafloor, and in some cases the impacts may seriously degrade healthy seafloor ecosystems. But, if properly sited
where the bottom is not naturally very productive, the impact may be very
small.

·     *   Water
quality in some cases may deteriorate, when shellfish farms are so massive that the
organic debris from them actually fouls the water or the bottom beneath the
shellfish farms.

·     *   The farm consumption of the natural food supply may compete with wild plankton feeders
in the ecosystem. Some states avoid this by requiring that farms be located in
areas that do not support significant wild shellfish populations.

Geoduck farm: protectourshorline.org

·     *  The siting can interfere with wild shell-fisheries or citizen’s access to the
waterfront and to natural marine resources. There is greatest potential for
this when aquaculture is located in intertidal areas; for example geoduck farming in Washington.

·      *     Introduction
of non-native and invasive species is often associated with aquaculture.  It may be the farmed species itself or
other species that hitchhike on the seed stocks or proliferate on the farms. A
prime example is the Pacific oyster, which has replaced native species round
the world, including in Washington. And industrial mussel farms off Prince
Edward Island are awash with massive growths of invasive tunicates.

·     *   Use of
pesticides is common in large-scale aquaculture, where competitors or
foulers in the farm beds or rafts are killed with chemicals. Examples include
pesticide applications to kill native ghost shrimp in the sediments of big
bottom-culture oyster farms in Washington State, and antifouling treatments on the P.E.I. mussel farms. Mussels themselves are often considered pests on salmon farms,
where chemicals may be used to get rid of them.

·     *   Important aesthetic
values of shorelines can be destroyed. Do you value the influence of natural
seascapes on our psyches and our arts?

For some time US aquaculturists have said that their
important industry is severely hampered by rich coastal dwellers who have paid
big bucks for a view of the sea. Well I don’t know about you, but I am not
rich, and I cannot afford ocean-front property, but I most certainly value the
access I have to sit on the shore and be soothed or inspired by the sea and
shore-scapes. Seafood farms of all kinds need to be sited and designed to
minimize their impacts on that. As with working waterfronts for commercial
fisheries, there is a place for everything, but some aquaculture developers
would suggest there is no place for us. And the federal government, by
promoting industrial aquaculture far offshore, would like to put the farms and
their inherent problems out of sight and out of mind.

There are many shellfish farms and few fish farms that do
not fall into the destructive patterns described in the points above. Always be
aware of the potential problems and choose which farmers to support – through
your buying choices and your political power to influence government policy. Nearshore
marine farming is regulated by individual states but often promoted by federal
funding and national policy, so you need to apply pressure at both levels to
make sure your coastal state is ready for expanding aquaculture development
with solid, ecologically defensible options, regulations and guidelines.