C) Fish Feeds and Nutrition

D)  Strait of Juan de Fuca and Mariculture

E) Societal and Sustainability

F) References Cited

A) Background Questions about Fish Culture

Q1- What is fish farming?

It is the raising of fish for food and/or restocking of natural fisheries. (In some tropical areas it may include tropical fish culture for ornamental aquarium markets).  Fish in fish farms are contained in several different ways including in ponds, tanks, raceways and cages (net-pens). Fish are farmed in both fresh water and salt water; one of the keys to successful fish farming being to maintain a high level of water quality in these containment systems so the fish remain healthy.

Q2- When did people first start to farm fish?

There are records dating back to 4000 BC that show the Chinese farmed carp in freshwater farms. Carp were also farmed in Europe during the Middle Ages. Modern fish farming has its origins in early attempts during the late 19th century to raise salmon and trout in hatcheries for stocking into lakes and streams. Some people also tried to do this with certain marine fish species, notably in Japan.

Q3- Why was it thought to be important to farm fish?

By the late 1950's and early 60's people were beginning to realize that the stocks of wild fish in the oceans were limited and that eventually there would not be enough of them to supply the world's needs. They realized that it would be necessary to farm fish or we would over-fish and deplete our natural stocks in the oceans and that consumption of seafood would have to be reduced. So they built on what had been learned in the early hatcheries. They improved rearing techniques and developed methods for growing fish to market size. In so doing, they started what can now be thought of as “modern fish farming”.

Q4- What difficulties did the first modern fish farmers encounter?

Successful fish farming requires a supply of fertilized fish eggs from parent fish held in captivity (broodstock), techniques to hatch these eggs and raise the delicate larval fish through their early stages, correctly formulated feeds to promote vigorous growth and constant supervision of the rearing environment so the fish remain healthy. There were challenges in all these stages, but research over the last 60 years has greatly improved our understanding and led to the development of fish farming industries that now play an important part in supplementing wild caught fish supplies. In fact, over a third of the fish we eat today is farmed. A good source of further reading on this is United Nation FAO (2004). The State of World Fisheries and Aquaculture (SOFIA):


Q5- What fish species are farmed?

The most commonly farmed fish are the large family of carps. These are farmed in many Asian and Eastern European countries, but not usually sold in the markets of Western Europe, North America or Japan. In the latter markets salmon is now the most commonly eaten farmed fish, together with others such as trout, catfish, tilapia, seabass and seabream, and yellow tail (amberjack).

There is also great interest in many parts of the world in growing other species of fish. Some of these include halibut, European turbot, tuna, cod, sturgeon, various species of snapper, red drum (red fish), cobia, Pacific threadfish, and many more.

Q6- What are the basic processes involved in fish farming?

There are usually three stages in the farming of most fish:

Q7- Are there other forms of fish culture being considered?

In the future, we expect different forms of mariculture to be combined nearby, such as shellfish culture and finfish culture.  In some areas these are also being matched with seaweed cultivation. Research involving this approach is occurring in the NE United States and particularly in Eastern Canada.  The idea is to extract nutrient and algae resulting from fed-fish culture. In some cases the extractive forms of mariculture alone may be practiced as a means to reduce coastal eutrophication (i.e., to reduce nutrient enrichment effects from other sources such as terrestrial agriculture or urbanization).  

Q8- What happens in a hatchery?

Many people are already familiar with the idea of fish hatcheries because they have visited public trout and salmon hatcheries used to produce juveniles for release into rivers, streams, and lakes. Commercial hatcheries operate in the same way and, in fact, have been responsible for some innovations, such as development of vaccines against certain fish diseases, which are now used in public hatcheries.

Hatcheries for marine fish production, such as halibut and turbot, are different from trout and salmon hatcheries only to the extent that the biology of the fish is different. When they hatch from the egg, marine fish are usually smaller than newly hatched trout and salmon and require special care in handling and feeding. Other freshwater fish, such as catfish and sturgeon, also have their special needs, but the hatchery concept is the same requiring gentle handling and feeding of delicate early life stages.

Q9- What are the young fish fed on?

Marine fish and other fish with very small larvae are usually fed on specially cultivated live foods to start with. These include microscopic, planktonic animals called ‘rotifers’ and brine shrimp, or Artemia, which are often, also, used for feeding small fish in aquariums. As the fish grow they are ‘weaned’ onto pelleted, formula feeds that contain all the essential nutritional ingredients for continued growth and good health. In the case of salmon and trout the first-feeding larva is big enough to take formula feeds to begin with, so you will never see systems for the production of live feeds in public salmon and trout hatcheries.  For marine fish, the process is more difficult and the focus of much study, but steady progress is being made.

Q10- What does the process of on-growing involve?

The fish must be cared for and fed so that they grow quickly and efficiently to market weight. To do this they must be kept in clean water and be fed on feeds that meet all their nutritional needs. As noted above, the containment systems for doing this can be tanks, ponds, or floating cages (net-pens), the overriding purpose in all of them being to maintain a healthy rearing environment.

Q11- What is meant by ‘healthy rearing environment’?

The most important thing is water quality and in the case of net pens, water and sediment quality. This is a term that can mean quite different things depending on the purpose for which the water is to be used. In fish farming it means that the water should contain enough dissolved oxygen to allow the fish to breathe easily, be free of any toxic materials that could harm the fish and that other chemical constituents should be at normal levels for unpolluted surface waters. In other words, this implies water that supports healthy fish life.  Fish farmers go to great lengths to assure good water quality in their farms including, for example, frequent or continuous monitoring of temperature, oxygen and in some cases plankton, cleaning of structures to ensure continuous unobstructed water flow and sometimes, where necessary, aeration or injection of pure oxygen to boost natural influent levels of dissolved oxygen.

Q12- What else do fish farmers do to maintain healthy fish?

Two things are especially important. First, feeds must be correctly formulated for the species that is being farmed and for the life stage that is being fed. There have been major advances in fish nutrition in recent years and it would now be extremely rare for any sort of nutritional deficiency to compromise the health of fish in farms.

Second, stocking densities must be maintained at levels so that the fish are at ease. Appropriate density levels vary for different species, different life stages and it depend on factors such as water temperature. A typical maximum density for larger fish in typical conditions in cages, such as salmon, would be 20kg per cubic meter (1000 liters of water), or, expressed another way, the fish would occupy 2% of the total rearing volume.

Q13- Why are some fish reared in cages in the sea and some in tanks or ponds on land?

Mostly, fish that are raised in tanks or ponds on land are freshwater fish. Some, such as catfish, do well in still water and are farmed in ponds, while others, such as trout, require flowing water and are grown in tanks or raceways. Where freshwater is available, these are good methods of farming fish. However, freshwater is an increasingly scarce resource and it is difficult, now, to find areas where water is available that can be used for fish farming.

There is much more salt water in the world. In fact, 97% of the earth’s water is in the oceans. Also, most of the fish we eat are saltwater fish. Because of this, much of the emphasis in the development of modern fish farming has focused on farming marine fish species in saltwater and this can be done in two ways. Either water can be pumped from the sea into ponds, tanks or raceways on land (‘pump ashore’ methods), or floating cages can be placed in the sea, where the natural forces of wind and tide provide the continuous flow of clean seawater that is needed.  In either case, fish farmer have to either own or lease the land (freshwater) or lease the aquatic lands (saltwater) and pay substantial fees and taxes for the opportunity to do so.

Q14- Why is a flow of clean water needed?

Fish require clean water flow to remove the wastes that fish produce and to replenish oxygen in the water that the fish need in order to breathe. The fish wastes consist of solid fecal material that remains after the feed is digested, and soluble, nitrogenous compounds, mostly ammonia (the end product of protein metabolism) that is rapidly converted to nitrate nitrogen in most oxygenated waters.  Nitrate is the natural and principal form of nitrogen occurring in the oceans.  Such wastes are produced by all animals and, in the case of fish, are dispersed by water flow and then assimilated by other organisms as part of the natural, aquatic, nutrient cycle. A similar process occurs on land when animal wastes are ploughed into soil.  Comparisons of human (municipal) wastes production to fish production are misleading and incorrect for the reasons cited in answer 24.

Q15- Which is the best method for farming saltwater fish?

It depends on the fish species and the nature of the coastline where they are being farmed. For example, flatfish, such as halibut and turbot do well in onshore tanks where there is a solid bottom on which to rest. European fish farmers produce turbot in this way in Spain. However, pumping seawater ashore is expensive, because it requires costly, failsafe pumping systems with backup systems that use often expensive, greenhouse-gas-producing energy.

By contrast, farming fish in floating cages is a passive, low technology method of achieving the water flow needed to maintain a healthy rearing environment and requires little or no inputs of external energy. Cages also provide less costly rearing space than tanks and they do not use up precious, often expensive, coastal land. For these reasons, where the right conditions exist for cage farming, it is a preferred method of farming for many species.

Q16- What are 'closed', 'recycle' or 'water reuse' systems?

These are systems in which water is continuously circulated through fish tanks and then treated by various physical and biological processes so that it can be reused, or recycled, through the fish tanks again. Treatment processes include solids removal, aeration and biological filtration to oxidize excretory fish wastes in solution. Like pump ashore systems, they are also expensive to build and operate and they consume substantial amounts of energy.  For some species, however, especially for the production of some juvenile fish, they offer the advantage of complete control over the rearing environment. But this is achieved at an energy and financial cost that is only justified where the value of the end product is high. For this reason they are not appropriate for producing fish, such as salmon, where the goal is to make it affordable to as many consumers as possible.  Political efforts to legislate the use of on shore tank systems only for species like salmon would doom the industry to failure as they couldn’t compete with production from overseas.

Q17- What are the right conditions for cage farming?

There must be natural shelter from storms and large waves, water depth in the range 15 to 50 meters and consistent tidal water exchange. Water flow should average speed greater than about 5 cm/s but this is not fixed. Rather it is dependent on stocking density and total biomass (total weight of fish) on a particular site.

Suitable conditions occur along the fjiordic and channel coastlines of British Columbia, Canada, Chile, Norway and Scotland and this is the reason that salmon farming has been so successful in these countries. Similar conditions exist in many other countries, though to a lesser extent. Where they do occur, such as in Greece, Japan, parts of Australia and in Washington and Maine, USA, cage farming of several species of fish is now established.

B) Environmental Effects and Regulation Questions

Q18- What is the background for regulation of Washington State aquaculture?

In the mid 1980s, amidst boom in Atlantic salmon culture worldwide, the Washington State Departments of Ecology and Fisheries commissioned a synthesis and review of the known effects of salmon net pen culture, which resulted in a milestone literature review by Dr. Donald P. Weston of the University of Washington (Weston 1986).  This document was widely acclaimed as the best-available review and interpretation of the literature at the time and is still a useful and pertinent document in many regards.  Immediately after the issuance of the report, Dr. Weston, in concert with the state resources agencies and interested parties, prepared the Interim Guidelines (SAIC 1986), which helped guide agency management and monitoring efforts for nearly a decade.  The Washington Department of Natural Resources adopted the Interim Guidelines as legal requirements of their aquatic lands leases.  The requirements were detailed, but may be summarized as having the following primary attributes:

There were no “end points” to this Interim Guideline monitoring, i.e., no regulatory threshold values or criteria were promulgated to determine if too much enrichment or impact was occurring.  The idea was to amass a database so that future regulations could be based on more detailed fact. 

Q19- What other studies have been done specifically for Washington State fish mariculture?

About 1990 a Programmatic Environmental Impact Statement for net pens was prepared by consultants for several state agencies under direction of the Washington Department of Fisheries.  The work was peer-reviewed by leading fisheries and oceanographic authorities, included the best available technical information and was drawn in part from studies published in technical appendices (Parametrix et al. 1991).  The purpose of the PEIS was to clarify the known technical impacts of net-pen rearing, to aid the site permitting and monitoring process.   Aesthetic impacts were also considered in this effort.  The results were transferred and adapted for use by the State of Maine but have evolved slightly differently in subsequent years (Normandeau Associates and Battelle.  2003).

Q20- What were the results of the 1980s and 1990s impact monitoring work in Washington State?

The Department of Ecology assembled all available monitoring information and hired an independent environmental consulting company (Stripland Environmental Associates) to assist them to quality control and analyze the data. Some of the data was discarded for technical or quality control reasons. It was found that most all measurable or significant impacts, as measured by infauna analysis and carbon content on the seabottom occurred within 30 m of typical commercial net pens, sometimes much less.  This was unexpected, as prior studies by independent, academic workers had focused on one particularly large site in Clam Bay that was the world’s largest array of pens and this pen system generated impacts much further away. This atypical system was subsequently reduced greatly in size and reconfigured to match the site specific carrying capacity.   The Department used the relevant monitoring data to construct a two stage benthic monitoring and performance standard system, as described below.

Regarding water column monitoring, some of the sampling was found to be of little value and was discarded. This included nutrient impact sampling, because the results appeared too variable and not really of consequence as commercial pens were all located in water naturally replete with nitrogen and phosphorus.  Dissolved oxygen monitoring up and downstream of pens was discontinued as all data (and thousands of data from Maine) showed that measurable effects only occurred a few meters downstream of the pens.  In practice, most fish farmers continued to monitor and record dissolved oxygen for their own use in managing their farms during the summer and fall periods.

Q21- When were federally authorized discharge permits issued?

Washington State was the first U.S. state to authorize NPDES permits for fish culture in 1996, using the studies and analyses discussed above as a firm scientific basis. In 2001 the permits were revised after a review of the first five years of data to include the measurement of copper (a trace metal used in animal nutrition and as an antifoulant on some of the nets) beneath and near the pens.

Presently, in 2005, all existing commercial net-pens meet or exceed performance standards that the Department of Ecology has in place.  See the publication attached to this website for more information. 

Q22- What are the performance standards for net pens?

(This section is a distillation of parts of a publication by Rensel [2001] available from this website).

Q23- What does this mean for marine fish farms in the Strait of Juan de Fuca?

If marine fish culture was allowed in the Strait, the farms would have to meet the same standards placed on salmon farms.  Physiological studies of marine fish, are planned that will allow modeling and prediction of effects of farm operation. 

Q24- Why should fish farmers be able to operate with no waste treatment?  Isn’t a net pen equivalent to the municipal discharge of thousands of people?

The analogy is seriously misleading and incorrect.  For years academic experts starting with Dr. Don Weston at the University of Washington Oceanography Department have pointed out that there are fundamental and important differences between fish culture wastes and wastes produced by municipal and industrial discharge operations.   In his landmark 1986 publication on floating fish farm impacts Dr. Weston pointed out that:

Since Dr. Weston published this work there has been rapid and sweeping improvements in the industry including:

Q25- What is meant by “assimilation” of wastes, pollution is pollution isn’t it?

Organic nutrients and elements such as carbon and lesser amounts of nitrogen and phosphorus make up the bulk of fish wastes from fish mariculture, both dissolved and solid forms.  These materials are bioavailable for use by the food web (protozoans, bacteria, plants, algae, invertebrates and fish).  Nitrogen and phosphorus fertilizers are actually added in huge quantities to some lake systems that are nutrient poor, in order to promote growth of the food web and fish production. 

These materials ARE different than persistent or toxic pollutants discharged by some other industries.  Properly planned, sited and operated mariculture will actually enhance food webs by stimulating more biomass and diversity in surrounding areas, the “halo effect” that surrounds many sources of organic enrichment in temperate marine waters.   A distinction is made here between dissolved wastes discussed above that can affect the growth of algae in other areas (not in the Strait) and solid wastes that are deposited, resuspended, and re-deposited on the bottom while serving as a food source for sea bottom (benthic) and demersal (immediately above the bottom) organisms.  More about this topic is included below.

Q26- How are fish diseases treated?

As with other animals there are different treatments for different types of disease.  Often in well planned and run fish culture, fish disease occurrence is a rare event.

Q27- Is it true that aquaculture uses lots of antibiotics?

No.  Absolutely not.

When fish mariculture began in the late 1960s, there were no commercially available vaccines to deal with pathogens.   At that time antibiotics and therapeutants were occasionally used to treat fish with an illness.  In acute illness, like vibriosis, the medication was often applied too late, fish were not feeding well in later stages of the illness and heavy losses sometime occurred.  

But over the years, vaccines have been developed to treat the fish before stocking in the cages.  In many cases, the fish are merely immersed in a vaccine mixture and the fish takes up the antigen through the gills and forms their own antibodies. Unlike cattle, fish growth rate declines with use of antibiotics, so there is no incentive to treat with expensive antibiotics.  In the past two decades, effective vaccines have reduced the use of antibiotics exponentially.   Exact figures are not available worldwide, but some sources suggest the reduction has been nearly 99%!   In the U.S. the annual use of antibiotics at fish mariculture facilities is less than a few hundred kilograms per year.  Compare that with the Center for Disease Control’s estimate of about 25 million pounds used in the U.S. annually for agriculture and you can easily see that concerns about mariculture on this account are misplaced!  Antibiotic use in net pens is so minimal, and the materials break down so quickly, that there is no comparison with agriculture use.  Worst-case published studies show that oysters held within salmon cages where treatment was made did not accumulate measurable amounts of antibiotics (See Washington State Programmatic EIS for floating fish culture).

Q28- Can hatchery diseases be passed onto wild fish?

Yes, but most fish health specialists and regulators believe that this does not pose a serious risk for wild fish for at least these two reasons:

First, in many countries including and especially the U.W., there are rigorous fish health and fish movement regulations designed to ensure that serious diseases are not transported from one region to another. So wild fish will not be exposed to any diseases that they are not already exposed to in the wild. 

Second, domestic fish broodstock are routinely screened for disease, so that larval fish starting out in the hatchery are free of disease. If disease occurs subsequently, therefore, it will almost always have entered from the hatchery’s water source and have come from wild fish that live there. As with all disease, however, both animal and human, there is no room for complacency and rigid adherence to fish health protocols is an integral part normal hatchery procedure.

Much has been written about fish parasites in British Columbia net pens and we would suggest the reader be very skeptical about internet sources of information that are not based on published studies by recognized experts and environmental agency findings. So called “sea lice” (an external parasitic copepod crustacean) do occur on wild and farmed fish in Puget Sound, but this has never been a significant problem with farmed fish in our state.  In part, this may be a result of the slightly lower salinity in Puget Sound compared with  more oceanic sites used elsewhere.

Q29- Can fish escape from hatcheries or rearing facilities and what happens if they do?

Yes, but escapes are rare because it is relatively easy to screen the discharge water from a hatchery so no fish can pass through. It is less easy to prevent escapes from net pens, and there have been a few, relatively large escapes of salmon from commercial cages in the 1990s. 

When they do happen the escaped fish will attempt to compete and survive in the wild as do fish that are deliberately released from public hatcheries to supplement natural fisheries. With some species, such as Atlantic salmon, there is concern now that escaped hatchery fish could compromise wild Pacific salmon genetically by breeding with them but several studies have shown that offspring are not viable. A further concern has been the escape of Atlantic salmon that could establish runs in local rivers and compete with wild salmon. Although theoretically possible, experience from tens of millions of intentional releases of these fish as juveniles shows that it is most unlikely and has never occurred anywhere in the world.   For marine fish, this concern is not a realistic problem as long as native marine fish from the same area are used.   

In any event, it is obviously in the best interests of all parties to try and make sure that farmed fish do not escape and this is a primary goal of hatchery and fish farm management.

Q30- What about genetic impacts?  Will accidentally released fish pollute the gene pool of wild fish?

For anadromous fish such as Pacific salmon, this could be true, but Washington State fish farmers no longer rear these species in marine net pens.  Instead they rear Atlantic salmon that are incapable of successfully interbreeding with Pacific salmon.   They are also extremely unlikely to establish runs even if massive numbers escaped from pens.   Repeated attempts to establish runs of this species around the world have failed.  Risk analysis by U.S. agencies such as NOAA rate this risk as near zero and even long time critics of mariculture such as Dr. Ian Fleming, director of the Ocean Sciences Center at Memorial University of Newfoundland support this view.  The fear has been that escapees will genetically overwhelm their wild relatives. Fleming argues that farming Atlantic salmon in the Pacific and vice versa can solve that problem.  Dr. Fleming acknowledged that his findings fly in the face of conventional wisdom that introducing exotic species is risky. But he said that Atlantic and Pacific salmon do not interbreed well.

Q31- What regulations are there to make sure fish farms do not create problems?

Regulations differ in different countries but they all seek to ensure the same thing, namely that fish farms produce safe, wholesome fish with the minimum of environmental impact. In most countries and especially the U.S., Canada, and much of Europe, fish farm regulations are extremely strict. Typically, fish farms are regulated to control where they can be located, what species of fish can be farmed, the quality and quantity of any discharge or the impact levels on the seabottom and water column, fish health, the use of chemotherapeutics, worker and navigational safety, and food safety.  In the U.S., fish farmers must utilize feed waste monitoring systems (e.g., underwater cameras, detectors, or upwellers) and they must use best management plans and have contingency plans and protocols for dealing with virtually all contingencies.  

Q32- Are the governmental regulations adequate to safeguard the environment from these impacts?

There are state and federal discharge requirements, rules and performance standards for freshwater and marine aquaculture in the U.S.   In Washington State, the rules are revised and updated after review and public comment every five years at a minimum.  The rules have been upheld in appeal boards (WSPCHB 1999 and 2000) and courts and found to be robust and well conceived.

Both the U.S. National Oceanic and Atmospheric Administration (NOAA 2001) and the British Columbia Aquaculture Review (SAR 1997) have concluded that salmon farming as presently practiced in the Pacific Northwest possesses low overall risk to the environment. 

Adequacy of the regulations depends on the ability of the regulatory agencies and the scientists who advise them to keep up with technical changes in the industry. This dilemma is not unique to fish farming, but we suggest that in the case of fish farming, the studies and reviews cited earlier provide ample evidence that regulatory regime under which it operates is both adequate and rigorous.

Q33- What involvement does the Washington Department of Fish and Wildlife have regarding commercial fish mariculture?

The Department of Fish and Wildlife is also actively involved in overseeing the industry and has posted its findings and opinions regarding the industry athttp://wdfw.wa.gov/publications/pub.php?id=00922

Q34- Is it possible to operate fish farms without any environmental impact?

No, but impacts can be very limited and there are typically positive effects of well-sited mariculture, such as food- web enhancement of diversity and abundance found around the perimeter of some fish farms.  Of course almost everything human beings do has some environmental effect. Agriculture, fisheries and now fish farming inevitably interact with the natural environment, because they are such an integral part of it. In some cases the interactions may be significant; in others they may be minor or even positive. The challenge for our human society is to figure out how we can maintain the standard of living to which we have become accustomed in developed countries, and advance that of those in undeveloped countries, while ensuring that changes in the natural environment are minimized. We believe that this is the course on which the fish farming industry is set and that what it has achieved up to now has been accomplished with an impact that is both minimal and acceptable.

Q35- Where can I find out more about the research that has been done?

Several Internet accessible references are given below. In turn these refer to thousands of other documents that are available in the scientific literature. They are:

C) Fish Feeds and Nutrition

Q36- What ingredients are used in the feeds?

Feeds for all animals must contain protein for growth, fat (edible oil) or carbohydrate for energy, and various minerals and vitamins (micronutrients) that are necessary for normal physiological and biochemical bodily processes. Because fish are cold blooded, they do not use as much energy as warm-blooded animals and, typically, do not digest or utilize carbohydrates well. Most fish feeds, therefore, are made from protein-rich ingredients and fat, plus various nutritional supplements.

Protein is usually supplied by a blend of high protein meals, such as fishmeal, soybean meal or soy protein concentrate, animal byproduct meals, such as poultry meal, and other plant proteins such as corn gluten. The fat component usually comes mostly from fish oil, though, as nutritional understanding improves, more vegetable oils are being used.

Q37- Are these ingredients checked for possible contaminants?

Yes. Fish feed manufacturers operate under strict regulatory controls and buy only legally approved ingredients. Additionally, they employ their own quality assurance checks for nutritional content and for possible contaminants. Recently, for example, there have concerns about the possible presence of compounds known as dioxins and PCB’s in certain animal feeds. These are persistent compounds that have been produced by other industrial activities and have found their way into the natural environment. Collectively, they are known as 'persistent organic pollutants' or POP's. Once in the environment they can be taken up by animals and plants that are later processed to become feed ingredients, such as fishmeal and oil. The regulatory authorities concerned with food safety set levels for the concentration of these materials in feed ingredients that are considered safe. Ingredient producers and feed manufacturers must comply with these regulations.

Q38- If farmed fish contain dioxins or PCB’s at very low levels, are they safe to eat?

Yes. In fact, because they are farmed, there is more control over possible contaminant levels in farmed fish than there is fish caught from the wild. Not that in either case should this be a reason not to eat fish. There is now general agreement among human nutrition professionals that people should eat fish at least twice per week as part of a balanced, healthy diet. Oily fish such as salmon and tuna are especially recommended, since they contain higher levels of certain fish oils that are now known to provide various important health benefits. The possible risk caused by the presence of tiny amounts of these contaminants is far outweighed by the health benefits that fish in the diet provides. See Harvard School of Public Health position on benefits outweighing risks of consuming seafood at http://www.salmonfacts.org/Downloads/Benefits_of_Eating_Fish.pdf

Q39- What is fishmeal?

Fishmeal is powdered, dried fish made mostly from small, bony, oily fish that cannot economically be processed for human consumption. Some fishmeal is also made from the waste from fish processing factories. It is an extremely high quality source of protein and is used as a premium protein source in many animal feeds. In fact, it has been shown that the use of fishmeal in animal feeds is a very efficient way to use this resource. A good source of further information on fish meal and fish oil is The International Fishmeal and Fish Oil Organization; http://www.iffo.net/

Q40- Why aren’t the fish from which fishmeal is made used for human consumption?

They are, but it is costly to process them because they are almost always small, bony, strong-tasting fish such as anchovies and sardines. There is only a limited demand for this sort of fish at a price that justifies the cost of processing, so only a small proportion of them are processed in this way and the rest are made into fishmeal. Clearly it would be preferable to use them all for human consumption and many efforts have been made to do this over the years, but to date, all the products that have been developed have limited market appeal and are relatively expensive. 

Q41- Are farmed fish artificially colored?

No, though some people have used the word ‘artificial’ to try to disparage the method that is used to produce the red color of farmed salmon. This is done by adding a pigment, or a combination of pigments to salmon feed. These pigments are manufactured replicas of pigments that salmon obtain from their food in the wild. In this respect they are like many vitamins that are produced by biological manufacturing processes to be used in nutritional supplements. This includes, for example, most Vitamin C that is used in vitamin supplements for animals and humans. It is not considered to be ‘artificial’ but neither is it ‘natural’ in the sense that it has been extracted from oranges or lemons. It is simply a manufactured replica of the natural compound and performs the same biological function.

Q42- Are hormones used to promote the growth of farmed fish?

No. Because hormones are sometimes used to promote the growth of farm animals on land and to increase milk yields in cows, people have assumed that they are used for similar purposes in farmed fish, but this is not so. In fact, there is no research that indicates that hormones fed in the feed to fish have a growth promoting effect. 

D) Strait of Juan de Fuca and Mariculture Questions

Q43- What kind of fish culture would occur in the Strait?

Presently, native marine fish are being considered for commercial culture or rehabilitation of wild stocks.  Hatchery techniques for many marine fish species are developing rapidly worldwide.  Once these fish become juveniles, they grow relatively fast and survive well on pelleted foods.  Their value to producers in some cases is much higher than salmon.  Marine fish culture is already occurring throughout the world and regionally in British Columbia where there are three hatcheries operating to produce juveniles. See Rust (in press) for a description of the culture of ling cod as one example candidate species.

Q44- Why consider fish culture in the Strait of Juan de Fuca?

The Strait of Juan de Fuca is almost unique in the contiguous 48 United States with regard to its strong currents and insensitivity to nitrogen enrichment.  Only a few other areas are similar such as the outer reaches of Cobscook Bay in northern Maine. 

Strong currents can result in environmentally friendly marine aquaculture, but current velocities must be limited or mitigated to suit the facilities used and the capabilities of the fish within the systems.

Q45- Why not grow salmon, I thought salmon farming was the main type of marine fish aquaculture?

Q46- Will fish mariculture in the Strait interfere with navigation, sport and commercial fisheries or wildlife use of the area?

Navigation:  There are dedicated, deepwater channels for ship navigation that are without exception too deep for marine aquaculture.    Nearshore navigation outside these lanes is used by commercial towboats (tugs with tows), fishing boats, yachts, and other small vessels.  The Corps of Engineers takes a special interest in these uses during permitting, and mariculture proponents generally would be advised to include an analysis of this factor in their permitting studies and applications.   Commercial towing companies may sometimes transit near the shoreline to catch counter currents or avoid strong main channel flows.  Mariculture siting can accommodate this need by planning and communication.   Yachts typically ply certain pathways too, and many of their courses are published in yachting manuals and atlases. 

Sport Fishing:  Sport fishing tends to focus on certain preferred grounds where fishing has repeatedly been good.  Most of these areas are also outlined and published in fishing manuals, books, and pamphlets, produced by government and private publishers.  Sport fishing may also occur at virtually any place in the Strait, and methods such as trolling tend to cover large expanses of the Strait so mariculture could conceivably extirpate some fishing, regardless of how much planning is done.  The point is to avoid the “hot spots” and focus on areas less frequently fished or not at all.

Commercial Fishing:  Siting of fish farms has to take commercial fishing into account.  There is only a relatively narrow depth interval suitable for mariculture activities, and much of the commercial fishing occurs further offshore.  Commercial fishing in the Strait can be divided into salmonid and non-salmonid fisheries as well as by Treaty Tribal versus Non-Treaty fishers as well as by gear group, troll (hook and line) or gillnet, or purse seine.  The figure below shows the catch areas ranging from area 4B in the western Strait to Area 6B in the eastern Strait.  


Washington Department of Fish and Wildlife Catch Reporting areas for the Strait.

The following summarizes some of the fisheries possibly affected by any type of development in the Strait:

E) Societal and Sustainability Questions

Q47- What benefits does fish farming offer?

The first and most obvious benefit is that it provides a renewable source of seafood that can be increased to meet the demands of an increasing and increasingly affluent world population. This cannot be said for our natural fisheries. They are already at the limits of their sustainable yield. If harvesting is increased further, we will exhaust them and they will collapse. The only way that more fish can be provided is through fish farming.

The second benefit is economic development. Fish farms mostly occur in rural and remote areas where jobs are scarce and where communities are struggling economically. Fish farming brings jobs in hatcheries, on the farms, in processing plants and in a whole range of supporting services such as trucking, general supply and equipment manufacture, and repair. In turn, these jobs provide the wealth to support secondary activities in communities such as schools, retail services and medical care. The European Community has specifically recognized the rural economic development benefits of fish farming and, over the last 20 years, has provided substantial economic assistance to the industry to help it get established in economically depressed rural areas. In many cases, also, the goal has been to provide jobs for fishermen that no longer have work because of declining natural stocks.

Q48- Is salmon farming sustainable?

Yes, we believe so, but we also recognize that there are limits as to how far it can develop based on current technology. The B.C. Salmon Aquaculture Review qualified its conclusion, cited earlier, with the words “as presently practiced and at present production levels”. If we look 10, 20 or 50 years ahead, farmed salmon production will almost certainly increase, but so too will the sophistication with which farming is practiced. Sustainability, in our view, is a concept that looks to the future not the status quo and it is achieved by constant adaptation to changing circumstances. Salmon farming has already demonstrated an extraordinary capacity for change and innovation. We are confident, therefore, that it will be able to adapt to new circumstances in future as they arise.

Among these circumstances will be the continuing pressure on natural fisheries to meet increasing seafood demand. As already noted, many of these fisheries are already over-fished and a limit has been reached on the sustainable amount of fish we can harvest from our oceans. Fish and shellfish farming is the answer to this dilemma, and its development is itself part of the process of continuous adaptive change that will allow us to increase our global seafood supply while ensuring the sustainability of our natural fisheries.

Q49-There has been criticism of fish farming in the press and on TV. Why is this?

In the judgment of many in the fish farming industry and of scientists working for the industry and government much of this criticism is unjustified. In some cases it comes from those who feel threatened by fish farming, such as commercial fishermen who see farmed fish as competition to wild fish they catch. In others it comes from shoreline property owners who do not want to see commercial activity in coastal waters and in particular near their properties.  And in other cases it stems for the fact that modern fish farming is 'coming of age' at a time of heightened ecological awareness. 

Quite rightly this means that all industries that use natural resources, including fish farming, should be closely scrutinized, and there are many special interest groups who have made it there business to make sure this is done. But in some cases, and regrettably in some newspaper articles and television reports, unsubstantiated assertions and scare stories have been given disproportionate coverage, while the science that answers many of the criticisms is ignored. A recent example is the Pew study on contaminants in farmed salmon that glossed over the fact that similar types of wild salmon were equally or more contaminated, and that contamination levels (in the low parts per billion) were within standards and not a threat, especially compared with the advantages of consuming the healthy omega-3 fatty acids in fish. 

Q50- Does this mean there are no problems?

Of course not, we discuss many of the problems above. Fish farmers are continuously improving and refining the methods they use just like most industries do. Traditional agriculture has been practiced for thousands of years, yet farmers and researchers are still striving to do things better. Modern fish farming is only about 50 years old. During this time it has been able to greatly accelerate its development by using modern technology, but the development process will continue forever. It is the nature of all human endeavors to strive for continuous improvement.  Unfortunately, much of this development is occurring overseas, not in the U.S.  

Q51- How can consumers be better informed about salmon farming?

Be skeptical of unpublished information and mass media interpretation of such information.  For example, farmed salmon from North America have similar or less content of contaminants than wild salmon.  This is simply because the fish protein in the farmed salmon feed comes from the Southeast Pacific waters, which are relatively pristine compared with northern hemisphere waters.  Opponents of mariculture typically lump all regions and types of salmon culture together, then focus on problem areas which do not include U.S. produced fish.   See links listed below for more information.

Q52- If salmon farmers can’t compete by producing in the U.S., how would marine fish farmers be able to?

Q53- Will fishermen be put out of business if we allow mariculture in the Strait?

Mariculture is an international business and most people acknowledge it will continue to grow regardless of what is done in the U.S.  In Japan and several other countries overseas, there is no separate word for fishermen and aquaculturists.  They are the same, and most fishermen capture wild fish as well as grow or contribute to aquaculture. 

In the U.S. and Canada this is not the case, as marine aquaculture has been dominated in recent years by a few large-scale corporate fish farm companies.  Yet even within the corporations or academic organizations doing research, many of the principal participants are ex-commercial fishermen or fisheries scientists. 

A new model of fish mariculture emerging in Hawaii is small-scale companies rearing high value fish for local and regional sales.  There is no reason this sort of grass roots model could not be adopted in the Northwest.   Treaty tribal and non-treaty fishers alike could be involved or have ownership.  Some Tribes and their fishers are already interested and participating in marine fish culture studies.  In the Northeast U.S., fishers and scientists are also involved in studies and pilot scale culture of marine fish in concert with mussel culture, such as in New Hampshire http://cinemar.unh.edu/.   We are aware of other regions with similar trends from California to Maine.

Q54- What is the outlook for marine fish farming on a global basis?

Globally the use of marine aquaculture for fish, shellfish and algae is increasing rapidly in many economies, except in the U.S. The U.S. has the technology, the skilled workers and the environmental ethic to conduct such work correctly and sustainably, but we may not have the will. There are potential food safety and national security issues with the high rates of seafood importation (~87% of our total consumption currently) seafood deficit of trade ranks high among the products adding to the imbalance. See World Aquaculture Society Plenary Talk of Dr. John Forster in 2011 at https://www.was.org/documents/MeetingPresentations/AA2011/AA2011_0600.pdf

F) References Cited

Anderson, D.M., P. Andersen, V.M. Bricelj, J.J. Cullen, and J.E. Rensel. 2001. Monitoring and Management Strategies for Harmful Algal Blooms in Coastal Waters, APEC #201-MR-01.1, Asia Pacific Economic Program, Singapore, and Intergovernmental Oceanographic Commission Technical Series No. 59, Paris. 264 p. http://www.whoi.edu/redtide/Monitoring_Mgt_Report.html

FAO 2004  State of World Fisheries and Aquaculture. United Nations Fish and Agriculture Organization.   http://www.fao.org/sof/sofia/index_en.htm

Mackas, D.L. and P.J. Harrison. 1997. Nitrogenous nutrient sources and sinks in the Juan de Fuca Strait/Strait of Georgia/Puget Sound Estuarine System: Assessing the potential for eutrophication.  Estuarine, Coastal and Shelf Science 44, 1-21

NOAA 2001. The net-pen salmon farming Industry in the Pacific Northwest. C.E. Nash (editor).  U.S. Dept. Commer., NOAA Tech. Memo. NMFS-NWFSC-49, 125 p.

Normandeau Associates and Battelle.  2003.  Maine Aquaculture Review.   Prepared for Maine  Department of Marine Resources.  Report R-19336.000  West Boothbay Harbor, Me. 54 pp.

Parametrix Inc. 1991.  Programmatic Environmental Impact Statement: Fish culture in floating net-pens.  Prepared by Parametrix, Battelle Northwest Laboratories and Rensel Associates for the State of Washington Departments of Ecology, Fisheries and Natural Resources. 161 pp and appendices.

Rensel, J.E.  2001.  Salmon net pens in Puget Sound: Rules, performance criteria and monitoring.   Global Aqua. Adv.  4(1):66-69. http://www.wfga.net/SJDF/reports/regulations.pdf

Rensel, J. E. and J.N.C. Whyte.  2003.  Finfish mariculture and Harmful Algal Blooms. Second Edition.  pp. 693-722 In: UNESCO Manual on Harmful Marine Microalgae.  D. Anderson, G. Hallegaeff and A. Cembella (eds). IOC monograph on Oceanographic Methodology. http://publishing.unesco.org/details.aspx?Code_Livre=4040

Rensel Associates and PTI Environmental Services.  1991.  Nutrients and Phytoplankton in Puget Sound.  Prepared for U.S. EPA. Region 10, Seattle.  EPA Report 910/9-91-002.  130 pp.

SAIC 1986.  Interim Guidelines for the Management of Salmon Net pens in Puget Sound.  Prepared for the Washington Department of Ecology Olympia WA. Science Applications International Co. Seattle.

Scottish Executive Central Research Unit.  2002.  Review and Synthesis of the Environmental Impacts of Aquaculture. The Scottish Association for Marine Science and Napier University http://www.scotland.gov.uk/Publications/2002/08/15170/9405

Weston, D.  1986. The Environmental Effects of Floating Mariculture in Puget Sound. University of Washington for the Washington State Departments of Fisheries and Ecology. 148 pp

WSPCHB 1999 and 2000.   Washington State Pollution Control Hearing Board.  Final finding of fact, conclusions of law and order.  Marine environmental consortium, Washington Environmental Council, Protect our waters and natural resources and Washington Trout.  V. State of Washington, Department of Ecology, Global Aqua-USA LLC and Cypress Island, Inc. summary at:  http://www.eho.wa.gov/searchdocuments/1998%20Archive/pchb%2096-257%20final.htm