Mariculture - Marine Aquaculture

• Deals with the farming of salt water species of fish, shellfish, seaweed and other marine products
• Learn to plan and manage the farming of a wide variety of marine life
• Self paced study, expert tutors, start anytime, 100 hours of learning to give you a sound foundation in marine aquaculture.

The term “Mariculture” refers to a sub-category of Aquaculture that deals specifically with Marine Aquaculture.

According to the FAO the term “Mariculture” (in its present usage) may be defined as:

Lesson Structure

There are 11 lessons in this course:

1. Aquaculture Production Systems
   • What is Mariculture
   • Purposes of mariculture
   • Classification of culture systems
   • Extensive production (Ep)
   • Intensive production (Ip)
   • Classifications based on system input
   • Open systems (off-shore and near-shore)
   • Semi-closed systems
   • Closed systems (on shore)
   • Common culture method for each marine category
   • Cage culture
   • Cage design: Floating flexible, floating rigid, semi-submersible and submersible
   • Hanging Culture: Raft and suspended trays
   • Long-line culture
   • Vertical or rack culture
   • Bottom culture: Bottom sowing and cultch lines
   • Stone, stake culture, net and umbrella culture
   • Semi-enclosed: flow through tanks
   • Closed Systems (CAS): Recirculating, raceways, and inland ponds
2. Starting a Marine Aquaculture (Mariculture) Business
   • Economics of establishing and running a farm
   • The need for a feasibility study
   • Economic analysis
   • Requisites for establishing a business
   • Factors to consider
   • Industry competition
   • Availability of leased and quotas
   • Economy of scale
   • Site selection and water quality
   • Properties of salt water
   • Water quality management
   • Environmental impacts.
   • Food chain problems
   • Using wild broodstock
   • Nutrient pollution
   • Chemical pollution
   • Spreading pathogens
   • Escapes
   • Habitat effects
   • Managing environmental impacts
   • Improving the genetic quality of fish
   • Biotechnology
3. Choosing a Species
   • Choosing a marketable species
   • What information is available?
   • Understand your competition before selecting a species
   • Common mariculture species
   • Selection criteria
   • Climate
   • Water resource
   • Finance
   • Scale of operation
   • Market demand and access
   • Availability of animals
   • Risk considerations
   • Product markets
   • Product, price and promotion
4. Finfish
   • Industry overview
   • Types of mariculture
   • Broodstock/seed supply
   • Growout
   • Commonly cultured species
   • Tuna
   • Atlantic salmon
   • Steelhead Salmon (Saltwater rainbow trout)
   • Yellowtail (Japanese Amberjack)
   • Sea Bass
   • Gilt-head sea bream
   • Water quality management
5. Crustaceans
   • Industry overview
   • Types of mariculture
   • Broodstock/seed supply
   • Growout
   • Commonly cultivated species
   • Penaeid shrimp (prawn)
   • Graspid Crabs
   • Lobster
6. Molluscs and Echinoderms
   • Industry overview - molluscs
   • Types of bivalve culture
   • Broodstock/seed supply
   • Growout
   • Abalone
   • Oysters
   • Cultured mussels
   • Scallops
   • Giant clams
   • Industry overview - echinoderms
   • Types of mariculture
   • Breedstock/seed supply
   • Growout
   • Commonly cultivated species
   • Sea Urchins
   • Sea cucumbers
7. Seaweeds and Aquatic Algae
   • Industry overview
   • Types of mariculture
   • Broodstock/seed supply
   • Land-based cultivation systems
   • Tanks
   • Ponds
   • Sea cultivation
   • Farming methods
   • Vegetative cultivation
   • Cultivation involving a reproductive cycle
   • Commonly cultivated species
   • Laminaria japonica
   • Porphyra sp.
   • Undaria sp.
   • Eucheuma seaweed
8. Pharmaceuticals
   • Pharmaceutical value of marine organisms
   • Examples of species used in marine biotechnology
   • Sea urchin
   • Sea cucumber
   • Marine sponges
   • Seaweeds (algae)
9. Diet Formulation and feeding
   • Feeding strategies
   • Nil input
   • Water fertilisation
   • Supplementary feeding
   • Complete diet feeding
   • Fish feed
   • Feeding and feed components
   • Environmental problems associated with fish feeding
   • Mycotoxins in feeds
   • Aflatoxins
   • Ochratoxins
   • Fumonisins
   • Trichothecenes
   • Managing mycotoxins in prepared feeds
10. Health Management – Diseases and Parasites
    • Causes of disease
    • Health management and mitigation strategies
    • Treatment of diseases and parasites
    • General principles
    • Common signs that fish are unhealthy
    • Common diseases of finfish
    • Emerging pathogens
    • Common diseases of crustaceans
    • Common diseases of bivalves (molluscs)
11. Harvest and Post Harvest Handling
    • Examples of product forms
    • Harvest/post harvest handling of selected species

Each lesson culminates in an assignment which is submitted to the school, marked by the school's tutors and returned to you with any relevant suggestions, comments, and if necessary, extra reading.

Aims

• Explain general mariculture production systems
• Discuss the factors involved in setting up a business
• Evaluate factors that need to be considered when choosing marine species for aquaculture in your region.
• Explain the commercial production of finfish
• Explain the commercial production of crustaceans
• Explain the commercial production of molluscs
• Explain the use and production of Seaweeds and Aquatic Algae
• Discuss the role of echinoderms in mariculture. Explore the pharmaceutical uses of marine organisms
• Explain general diet formulation and feeding
• Describe issues related to the health management of marine animals used in aquaculture.

Mariculture is a complicated business and anyone who intends entering it should undertake extensive research on the topic. It requires a large investment of time and money over a period of years. By conducting a feasibility study before starting a farming venture, you can determine how much it will cost to operate a farm and if the right conditions for growing a particular species are available.

Given the high start-up costs, most successful mariculture operations target high-value fish, such as ornamental fish, as well as food fish, such as red snapper, salmon, and eels. Shellfish mariculture has a broader product range including clams, oysters, shrimp, scallops, and crabs. Algae are often produced with finfish or shellfish to provide a food source for the primary product.

A major cause of failure in any aquaculture or mariculture operation is poor marketing. In mariculture, farmers are competing with wild-caught commercial species. This can be beneficial, given wild stocks are declining and seasonal availability can produce supply shortages that a producer can fill if he or she can arrange harvests for the times of shortages. However, if wild catches are plentiful, the producer may not be able to sell the product at a price that covers costs.

Extensive Mariculture Production (Ep)

An extensive production system involves the use of natural waters (i.e. oceans, saltwater estuaries, rivers, dams, lakes and various impoundments). It is a system where animals are stocked, allowed to spawn and increase in number and size. 

Sometimes there will be some input in terms of water, fertilization, feeding and/or protection.  Usually a simple stocking and harvesting routine is followed. 

Extensive culture systems have been employed throughout the world since man learned to fish, particularly where there are shallow coastal lagoons, as in river deltas in the Tropics and Mediterranean areas (Nile delta, Rhone delta, lagoons and canals in the Adriatic Sea, Yucatan Peninsula coastal lagoons in Mexico, etc), and in more recent times when impoundments have been stocked for angling recreation.

This system is also employed for casual harvesting (i.e. non commercial) by rural communities. It is generally accepted that it is less expensive to produce a harvestable crop from an Extensive Production system than that from an Intensive Production system.  Water is available at little cost, manpower needs are lower and the degree of expertise required from both the farmer and his workers is considerably less for extensive than intensive fish production. 

The estuaries, ocean, lakes, and dams used for extensive production are usually large and have sufficient food and cover to support a large number of fish and allow them to grow reasonably quickly to a marketable size.  However, they will grow more slowly than fish which are force fed under intensive conditions.

The mass of fish harvested is considerably less on a per hectare rating than under intensive production. Nutritional quality may be more variable also, depending on water quality and environmental conditions that determine fish food quality (climate variability, nutrient input to lagoons and dams, competition amongst species for the same food sources).   

Intensive Mariculture Production (Ip)

An intensive production system (IP) is managed to ensure optimum water conditions, feeding regimes and production of marketable flesh at all times. This is important for high production.

It requires a well designed and managed production unit so water flow, water quality, light intensity, oxygenation, waste build up, feed, predation, competition and most other factors affecting or limiting production are efficiently controlled, improved or otherwise manipulated. Reproduction can sometimes be initiated slightly out of season by manipulating water temperatures, oxygen and light intensity. 

Pools, raceways or dams are typical units for intensive production. They are designed and constructed to offer the farmer as much control as possible, to circumvent problems and to improve any natural limitations. They also enable the farmer to determine exactly his marketable stocks and have them available whenever they are needed. 

Intensive aquaculture for example may involve artificial spawning by means of hand stripping, with or without hormone stimulation. The ova (eggs) are hatched, and the young are raised, under protected and controlled conditions. They are regularly sorted and those of the same size are kept together. The weaker fish (those that would normally have died had they been in a natural habitat) are now a useable and marketable additional percentage. 

In a hatchery, diseases that are often dormant in wild fish population may suddenly develop and spread quickly because of the large number of fish contained in a small amount of water. Epidemic proportions may be reached quickly. Treatment is imperative to ensure a suitable harvest and is often costly. However, most sicknesses can be quickly and efficiently treated.

To avoid the spread of disease, fish must be surveyed often, and procedures for fish health monitoring must be put in place.  Observation, experimentation and selection for improved breeding are usually extremely difficult where extensive production is practiced, but relatively easy in a hatchery or intensive farm. Selection for fast growth, good feed conversion, marketable characteristics and many other factors are usually done over a long period of time.

Mariculture operations must be able to maintain salinity levels and adapt to the changing needs of the culture animals.
Disease-free seawater can be made with sea salt, but it is often expensive.
Raw seawater can be expensive given the typically high value of waterfront property.
Raw seawater can introduce diseases and competitors that can devastate culture organisms.

Some biological and natural distribution information for the species should be known before a site is selected i.e. is the species found naturally in that location, are the temperature limits of the area within that of the species etc.

For open or flow through systems, the area should be of a suitable depth, have good tidal flow with pristine conditions and ideally sheltered from intense wind and wave action.