Aquaculture producers raise and ship hundreds of species and varieties of ornamental freshwater and marine fish and invertebrates.
Most are freshwater fish, including tropical species (e.g., angelfish, barbs, mollies, swords, and tetras) and several temperate species (e.g., goldfish, and koi). Marine species include colourful reef fish, corals, molluscs, and crustaceans.
Ornamental species are shipped throughout the U.S. and the world to wholesalers, retailers and the public.
Given the large volume of the trade, numerous shippers and destinations, and the variety of species shipped, there is increasing regulatory interest in the potential for transporting hitchhiking species along with shipments of ornamental fish and invertebrates.
However, careful attention throughout the process of preparing specimens for shipping, the method used for shipping, and inspection by the receiving customer can effectively reduce this risk.
Producers should take steps to exclude plant material and debris, as well as snails, clams, insects, crayfish, tadpoles, turtles, wild fish or other undesirable species from holding tanks and shipping bags.
Culture:
Most ornamental species are raised as monocultures in tanks or in ponds. This reduces handling stress for the cultured species during harvesting and grading, leading to a better product, and reduces labor costs for the producer.
In a few instances, two ornamental fish species may be cultured together in ponds, typically with one species occupying the bottom and another swimming at the surface to facilitate selective harvest. It is also relatively common to maintain several species of ornamental, sessile marine invertebrates within the same culture system.
Typically, other species within culture systems are undesirable and should be eliminated because they compete with cultured species for feed, reduce water quality because of increased biomass, prey upon cultured species, or serve as reservoirs for pathogens.
These pest species (wild fish, tadpoles, turtles, crayfish or snails) seldom occur in culture tanks, but may be present in culture ponds or in tanks holding recent harvests from ponds.
Grading:
Producers harvest ornamental fish from ponds with traps or seines and may conduct partial or complete harvests depending on the cultured species and customer orders. Grading is done in a holding or packing facility, though some producers also grade at the pond immediately after harvest.
In tank culture, fish are netted from tanks and then graded. Fish are graded for size, colour and perhaps sex. Undesirable individuals and other species are removed and discarded. Although mechanical graders are used to grade some species for size, most grading is done by hand.
Ornamental species are sold by the individual rather than by weight, and because appearance (e.g., colour, uniformity) is important to the customer, producers pay particular attention to grading. Proper hand grading is the primary method ornamental aquaculturists use to exclude unintended hitchhikers from shipments.
Packing:
Ornamentals are held in tanks until they are packed for shipping. Individual fish and invertebrates are counted out to fill orders so there is another opportunity to remove any undesirable animals.
Ornamental fish and many invertebrates are shipped in plastic bags containing clean water, shipping additives (e.g., salt), and oxygen gas. Some invertebrates are shipped “dry,” with individuals wrapped in moist towels inside plastic bags.
The bags are placed in a polystyrene box inside a cardboard box. Ornamental fish and invertebrates are shipped by truck and by air. There is little opportunity for hitchhiking species to contaminate shipments during the packing and shipping stages.
When shipping boxes reach their destination, customers unpack and inspect the contents to determine if their expectations of quality and quantity are met. During this inspection, culls of any sort (not only undesirable species, but also poor quality individuals of the species ordered) are noted. A large number of culls will lead to customer dissatisfaction.
Aquatic plants:
Native and nonindigenous tropical, subtropical and temperate freshwater plants are cultured in the U.S. for aquariums, water gardening and wetland restoration. Aquarium and water gardening plants are produced outdoors in concrete tanks or plastic-lined wooden vats, or in greenhouses in tanks or on growing tables.
The tanks are filled with a shallow layer of mulch covered with a sand layer. Hydroponic growing tables are used to produce potted plants that are floated in plastic foam sheets or plastic trays on several centimeters of fertilized water.
Plant production systems are closed (i.e., water does not flow through) to exclude non-target plant species and plant pests and to retain fertilizers to benefit growing plants. Tanks and vats are managed as clear water systems for the best light penetration to the growing plants and to facilitate inspection and harvest.
Native predators can be stocked in tanks and vats as biological controls for both native and nonnative species. Snails may be used to clean tank and plant surfaces; freshwater copepods and Daphnia sp. will maintain water clarity; fry or fingerlings of native fish (e.g., sunfish or bass) will eliminate a variety of vertebrate and invertebrate species.
Production systems should be inspected frequently to 1) remove weeds that compete for space, light and nutrients and 2) remove plant pests.
Harvesting:
Aquarium and water gardening plants are harvested to order because they are perishable. They are shipped as clipped bunches (primarily floating plants) or bare root or potted plants (submerged or emerged plants). Bunches are bound with rubber bands or lead strips. Potting material for potted plants is spun glass contained in a ventilated, black plastic pot.
Shipping:
For shipping, all plants are wrapped in folds of damp paper, placed in a plastic bag or wrapping, then placed in a heavily waxed shipping box or foam box, and finally in a cardboard box. Aquarium and water gardening plants are ordered and shipped by count and each plant should be visually inspected for size, health, appearance and cleanliness.
They should be inspected again during packing to ensure the correct number and plant species is being shipped. Each shipping box may contain several species. To be successful, aquatic plant producers must deliver clean, undamaged plants identified by common and taxonomic names, and accurate plant counts.
Nonindigenous hitchhikers (e.g., live snails and unwanted plants) should be eliminated when plants are carefully inspected during culture, harvest and packing.
Marine shrimp and freshwater prawns:
Marine shrimp and freshwater prawns are transported across state and international borders in various stages of development (post-larvae, juveniles and adults).
During the hatchery stage, marine shrimp larvae are fed a combination of microalgae and Artemia. If larvae are transported during this stage, it will be diffcult to eliminate the microalgae present in the water.
Larval shrimp can tolerate gentle handling and can be poured through an aquarium net or screen to separate them from the water containing microalgae. Then they can be rinsed and placed in water of similar quality to ensure that minimal microalgae are present during transport.
Larvae are often transported in water containing algae, then separated from the water on the receiving end. The water should be treated with bleach before it is released down a drain. These practices will prevent the spread of microalgae species to regions where they may not be native.
Nursery:
Marine shrimp and freshwater prawn broodstock and hatchery facilities exist worldwide. There are large marine shrimp companies with grow-out farms in various countries. Shrimp and prawns are transported in the post-larvae or juvenile stages across state and international borders.
Broodstock are maintained in specific populations selected for traits such as growth rate and disease resistance. When post-larvae develop, they are packed in plastic bags within Styrofoam® boxes and shipped via air freight. Nursery stage shrimp and prawns are usually cultured in clear water (without phytoplankton) rather than green water (with phytoplankton).
Clear water production reduces the likelihood of hitchhikers being present in the shipping water. However, even under clear water conditions the water may contain many microscopic organisms.
The two most common are microalgae and motile ciliates; others are zooplanktonic organisms such as rotifers, copepods and protozoa (i.e., Vorticella spp.) and others. To reduce the potential of transporting these microscopic organisms, separate the post-larvae from their culture water and rinse gently before packaging them in transport water of similar quality that is free of these organisms.
When shipments of post-larval shrimp and prawns are received, it is common practice to suspend the bag within the culture tank and add water from the new culture system to acclimatize post-larvae to the new water quality.
The entire contents of the bag, water and post-larvae and all organisms within the water, are then introduced to the culture tank. However, you should not introduce transport water into a grow-out culture tank because you may be adding motile ciliates, which can proliferate rapidly in this new environment.
A better practice is to assume these organisms are present and separate post-larvae from the transport water with an aquarium net or a screen before stocking them into the culture tanks. The water separated from the shrimp should not be put down the drain.
This water should be collected in another container and treated with bleach (at 20 mg/L) to kill all the microscopic organisms.
Marketing and growout:
Shrimp and prawns cultured in ponds and raceway tanks are usually separated from water and placed on ice for transport to market or a processing facility. However, adult shrimp and prawns may be shipped in live-haul tanks for live sales or to transport broodstock between two sites.
Styrofoam® shipping boxes may also be used to transport small numbers of adult broodstock. Hitchhiking organisms that may contaminate these shipments include all the microscopic organisms mentioned previously, as well as sessile epicommensal organisms (e.g., Epistylis spp.), which can colonize the carapaces of shrimp and prawns, diving beetles (29 families in the Suborder Heteroptera), which can be free swimming or found as eggs (e.g., waterboatman, Family Corixidae) attached to the carapace of freshwater prawns, and dreissenid mussel veligers.
If shrimp and prawns have visible external organisms on their carapaces, they should not be transported. Transport water drained at the receiving site should be collected and treated with 20 mg/L bleach to eliminate potential hitchhikers.
Authors:
Paul W. Zajicek, Jeffrey E. Hill, Nathan Stone, Hugh Thomforde,
Cortney Ohs, Diane Cooper, Gef Flimlin, Brad McLane and William D. Anderson
