aquaculture

Grass carp, or white amur (Ctenopharyngodon idella) are originally from China. They are a different species from the common carp. Aptly named, grass carp feed on vegetation, and will consume pelleted food when available. They can grow to 35 kg, however they rarely exceed 10 kg when stocked in ponds.

Kenneth Williams and Glen Gebhart have published a report entitled Controlling Aquatic Vegetation with Grass Carp. From the introduction:

Excess aquatic vegetation causes problems in both aquaculture ponds and in farm ponds used for either sport or food fish production. The main problems caused by rooted and filamentous aquatic vegetation in aquaculture ponds are: interference with fish harvest operations, use of nutrients that could be more efficiently utilized by phytoplankton for dissolved oxygen production, reduction of water circulation that increases stratification and lowers dissolved oxygen levels. Excess aquatic vegetation in farm ponds interferes with hook and line harvest and increases the possibility of overpopulated, stunted forage fish populations, and reduces the aesthetic value of the pond for swimming and recreation. Grass carp are used to great advantage in both situations.

Grass carp do not breed easily in ponds, in their natural environment preferring swift moving water. Kenneth Williams, again, has published information on Grass Carp Propagation. From the introduction:

Spawning does not occur in ponds and lakes. Reproductive organs reach an incomplete state of development and become dormant. As water temperature rises above 80 degrees F. eggs and milt are resorbed into the fish.

Natural spawning conditions do not exist for grass carp in the United States with the possible exception of the Mississippi river. Successful grass carp spawning and hatching requires a thorough knowledge of the fish, healthy brood stock, gentle handling and an understanding of induced hormonal spawning techniques.

Michael P. Masser has published a document July 2002, entitled Using Grass Carp in Aquaculture and Private Impoundments. From the abstract:

The U.S. Fish and Wildlife Service, in cooperation with Auburn University, first introduced grass carp into the U.S. in 1963 to investigate their usefulness in controlling aquatic vegetation. No native North American species of fish is as strictly herbivorous as the grass carp. Therefore, there are no native species available for aquatic vegetation management. Grass carp have proven to be effective in controlling many species of algae and submerged aquatic vegetation.

Larry Sanders, Jan Jeffrey Hoover, and K. Jack Killgore have published a 1991 report entitled Triploid Grass Carp as a Biological Control of Aquatic Vegetation. Triploid grass carp are sterile, thus eliminating the concern of the species forming sustainable, breeding populations. The article reviews

the development and biology of the triploid grass carp and provides recommendations for its use as a biological control of nuisance aquatic vegetation. Triploid and diploid grass carp are morphologically identical and, reproduction notwithstanding, are assumed ecologically similar. Therefore, most data obtained from studies of diploid fish should be applicable to triploid fish.

Aquaculture CRSP report on the Polyculture of Grass Carp and Nile Tilapia with Napier Grass as the Sole Nutrient Input in the Subtropical Climate of Nepal. The objectives of the research:
1) Evaluate the growth of grass carp and tilapia fed with napier grass in polyculture.
2) Evaluate the nutrient and water quality regimes of pond water.
3) Determine the composition of foods consumed by Nile tilapia.
4) Determine the optimal ratio of grass carp to Nile tilapia in polyculture.

The FAO have published a summary of grass carp culture entitled Cultured Aquatic Species Information Programme Ctenopharyngodon idella. As part of a section on status and trends, they observe:

Grass carp not only grow quickly but have a low requirement for dietary protein. They can be produced at low cost by feeding them with aquatic weeds, terrestrial grasses and by-products from grain processing and vegetable oil extraction. Seed can be produced through induced breeding at a large scale and very low cost. The culture of grass carp can be well integrated into crop farming and animal husbandry, to maximize the utilization of natural resources. On the other hand, it is a large fish without fine inter-muscular bones. It is acceptable to consumers in many countries and it very likely has good potential for development. The market for grass carp is close to saturation in the eastern part of China, where aquaculture is well developed now. However, there is still a considerable potential market in central and western China and many other developing countries.

The FAO has published a document entitled ‘Farming Freshwater Prawns – A manual for the culture of the giant river prawn (Macrobrachium rosenbergii)‘ (2002).

From the abstract:

This manual provides information on the farming of Macrobrachium rosenbergii. Many of the techniques described are also applicable to other species of freshwater prawns that are being cultured. The manual is not a scientific text but is intended to be a practical guide to in-hatchery and on-farm management. The target audience is therefore principally farmers and extension workers. However, it is also hoped that, like the previous manual on this topic, it will be useful for lecturers and students alike in universities and other institutes that provide training in aquaculture.

After a preliminary section on the biology of freshwater prawns, the manual covers site selection for hatcheries, nurseries and grow-out facilities, and the management of the broodstock, hatchery, nursery and grow-out phases of rearing. Harvesting and post-harvest handling are also covered and there are some notes on marketing freshwater prawns. The reference and bibliography section is generally restricted to a list of relevant reviews, as well as other (mainly FAO) manuals on general aquaculture themes, such as water and soil management, topography, pond construction and simple economics. Every attempt has been made to illustrate the management principles described in this manual by photographs and drawings. The manual contains many annexes on specific topics, such as the production of larval feeds, size variation and stock estimation. The final annex is a glossary; this lists not only terms used in the manual itself but also terms which the readers may find in other documents that they may consult.

According to a report published by SEAFDEC/AQD, Philippines, milkfish (Chanos chanos) farming is a centuries-old industry in Indonesia, the Philippines, and Taiwan.

Research into the culture of milkfish has not been limited to the Philippines. Research into the feasibility of milkfish culture in Fiji has been undertaken. Esteban Dela Cruz has published a report 1997, through the FAO, entitled, Potential of milkfish farming development in Fiji. From the summary:

Milkfish has been a successful food industry in Asian countries like Philippines, Taiwan, and Indonesia. The Government of Fiji had wanted to develop a similar industry, and so enlisted the help of the Food and Agriculture Organisation of the United Nations. The South Pacific Aquaculture Development Project (Phase II) devised this survey to ascertain the extent of the milkfish stocks in Fiji waters, and further to investigate the possibility of milkfish farming in Fiji. Such farms have already been established in Nauru, Kiribati and Tuvalu, and it was thought that milkfish farms would be not only a good source of protein for human diets and an alternative to depleting fish from the sea (and thus a way to ameliorate an environmental pressure), but also a source of income for villages and farmers as tuna bait as well.

There are many sites suitable to develop milkfish farms in Fiji, such as unused rice paddies, salt or prawn farms, or swamps and marshlands. Farmers need to acquire skills in preparing the ponds for stocking by draining, drying, leveling, and liming or poisoning for unwanted animals (where necessary). Also, dykes and water gates must be constructed and farmers must learn to feed the ponds to grow benthic algae (brackishwater ponds), and plankton (freshwater ponds). The design of the farms must take into account that milkfish swim against the current, so the catching ponds will be placed to concentrate fish from the grow-out ponds for easy harvesting.

The Fiji Islands Trade and Investment Bureau has published a report (2001) entitled Milkfish Farming Project Profile. This report outlines the investment potential of a milkfish project, including government incentives, and some forecast costs. Their summary of the market:

Market Milkfish is currently used as an intermediate good – an input – in the form of live baits for catching fish. Given the fact that milkfish baits supplements the longline tuna industry, which earns around F$40 million in export income, is indicative of the fact that there is a considerable market locally.

Prospective investors should do their own due diligence, and use the figures purely as indicators rather than current market realities.

According to the National Agricultural Statistics Service (USDA) Washington, D.C., from information released in February, 2006, the total value of all sales, both fish and eggs, received by trout growers in the 20 selected States totaled 74.2 million dollars during 2005, an increase of 4 percent from 2004. For the Nation, sales of fish totaled 69.1 million dollars for 2005, while egg sales totaled 5.14 million dollars. The State of Idaho accounted for 51 percent of the total value of fish sold.

The number of trout 12 inches and longer sold during 2005 totaled 55.5 million fish, up 12 percent from the previous year. The average price per pound was $1.05, up 2 cents from 2004. The value of sales for the 2005 marketing year was 62.6 million dollars, up 5 percent from 2004. Based on the dollar value, 67 percent were sold to processors and 19 percent were sold to fee and recreational fishing establishments.

Information about trout production and consumption is available online from 1995 from the National Agriculture Statistics Service.

Skip Thompson has published a series of reports which build into a resource entitled What Do I Need To Get Started In Trout Farming? There is also some useful information on the care of fingerlings.

George W. Klontz, Professor of Aquaculture, from the Department of Fish and Wildlife Resources, University of Idaho, has published a Manual for Rainbow Trout Production on the Family-Owned Farm. From the introduction:

This presentation is intended for the family-owned and -operated trout farm producing 15-50 tons (30,000-100,000 lbs.) per year. The impetus for my writing this text comes from hearing genuine concerns about rainbow trout in the marketplace. Chefs, restaurateurs, and retailers have stated quite clearly and repeatedly that they expect farmed trout to be of high quality, delivered when needed, and presented in the form required. Stated another way, quality, timeliness, and portion control are the bywords of successful trout production and marketing. Notice that selling price is not among the concerns.

Geoff J. Gooley, from the Australian Rural Industries Research & Development Corporation, has published a report on trout farming in the Australian context. A summary is online, and full document is available for free download.