aquaculture

The Native Fish Conservancy is about preserving the North American aquatic heritage. A group of like-minded conservationists, they are seeking other people, willing to donate time and skills to the ongoing development and production of the e-newsletter, the web site, and marketing. The Native Fish Conservancy is a not-for-profit, volunteer run organisation. Although their emphasis is on North American species, no doubt they would welcome international members. From a more commercial aquacultural perspective, a lot can be learned from people who keep fish as a hobby – people who have the time and resources to carefully develop breeding, feeding, and raising strategies that could be scaled into full scale commercial enterprises.

I’m pleased to be offer readers aquaculture news, articles, and market reports (or click on the ‘News’ tab). The articles and news can be translated with the automatic (machine) translation facility (in the sidebar). My apologies for the less than perfect translations – however they are getting better all the time.

The Australian Centre for International Agricultural Research (ACIAR) is a statutory authority that operates as part of the Australian Government’s development cooperation programs. The Centre encourages Australia’s agricultural scientists to use their skills for the benefit of developing countries and Australia. Geoff Allan and Don Fielder (from ACIAR) have published a .pdf document for download entitled Mud Crab Aquaculture in Australia and Southeast Asia.

The summary:

Mud crab aquaculture has been practised for many years in Southeast Asia, based primarily on capture and fattening of juvenile crabs from the wild. There is an unmet demand for mud crabs and this has led to over-exploitation in many areas. Difficulties with obtaining wild caught juveniles for farming operations, plus concerns of further over-exploitation, have led to major investments in research into hatchery techniques. To review mud crab aquaculture in Australia and Southeast Asia, ACIAR funded a scoping study, followed by a workshop to review the study and discuss status and problems in different regions. Those results are presented in this report.

A.F. Medina Pizzali has published research via the FAO entitled Low-Cost Fish Retailing Equipment and Facilities in Large Urban Areas of Southeast Asia. Of particular interest from a mangrove crab perspective is a case study from metro Manila.

Four species of crabs are of commercial importance in Metro Manila; these are pelagic swimming crab (Portunus pelagicus), mangrove crab (Scylla serrata), peregrine crab (Varuna litterata) and horned ghost crab (Ocypode spp). Mangrove crabs are considered a delicacy and are always marketed alive. The Metro Manila market is characterised by consumer preference for live mangrove crabs which command high prices; in particular, ripe females fetch premium prices. The domestic market is supplied with mangrove crab the year-round, with a peak season from May to September. During the Christmas period, there is an increased demand and prices of live mangrove crab are relatively higher.

Brian Coad has published a substantial work in the Freshwater Fishes of Iran.

From the introduction:

This work is meant to provide a guide to the freshwater fishes of Iran. There are no modern keys to this fauna, some available books are incomplete or cursory treatments or outdated, and the detailed and diverse scientific literature is widely scattered in time, languages and journals. Iran lies at a region of major zoogeographical interchange and has a diverse and interesting ichthyofauna about which comparatively little is known. An accurate identification is a pre-requisite for further scientific studies and this website aims to serve that purpose and to be an introductory guide to the fishes. The guide is aimed at a mixed audience, including scientists familiar with ichthyology to whom some introductory sections of this work will be superfluous, and those whose knowledge of fishes is embryonic or who may have limited access to literature sources.

This work has been carried out over a period of over 30 years from my first arrival in Iran in January 1976. In that year, 7 articles were published strictly on Iranian fishes (3 on parasites, 1 on pesticides, 1 on fisheries, 1 describing the blind white fish and 1 a summary of the latter; 2 were in Farsi). In 2006, 160 articles on Iranian fishes appeared, along with many relevant works from neighbouring countries, works on the aquatic environment in Iran and works on taxonomy and systematics relevant to Iran. The study of fishes is now a very active field within Iran and the Middle East. Accordingly, 2006 is the last year that this work was updated although some systematic and taxonomic studies may still be incorporated.

The potential of duckweed as a high-protein feed resource has been reported here previously.

Bui Xuan Men, Brian Ogle, and T R Preston have published research findings entitled Use of restricted broken rice in duckweed based diets for fattening Common and Muscovy ducks (Livestock Research for Rural Development, Volume 8, Number 3, September 1996). From the abstract:

A feeding system of restricted levels of broken rice (60 to 80 g/day) with free access to fresh duckweed appears to be appropriate for the Common type of duck typically used for foraging on rice fields throughout Vietnam. More research is needed in order to ascertain if the apparent capacity of Common ducks to eat large quantities of duckweed really is a comparative advantage and, if so, how this can best be used to improve the economic benefits to small scale poor farmers.

The authors have also published Duckweed (Lemna spp) as replacement for roasted soya beans in diets of broken rice for fattening ducks on a small scale farm in the Mekong delta (Livestock Research for Rural Development, Volume 8, Number 3, September 1996). From the abstract:

There was a slight indication (P=0.1 for females and 0.34 for males) that carcass yield was reduced on the duckweed treatments but differences were small. There were no differences in weights of chest and thigh muscle nor in heart and liver weights.

For farmers growing the duckweed there were economic benefits on all duckweed diets with best results from the complete substitution of the soya beans.

Paul Skillicorn, William Spira, and William Journey have published an extensive report entitled Duckweed Aquaculture – A new aquatic system for developing countries (The World Bank – Emena Technical Department, Agricultural Division). From the foreword:

Although duckweed species are familiar to most people who have seen the tiny aquatic plants covering stagnant water bodies, few people realize their potential. Until a few years ago, man made little use of duckweed species. Their unique properties, such as their phenomenal growth rate, high protein content, ability to clean wastewater and thrive in fresh as well as brackish water, were only recognized by a few scientists.

Prior to 1988 duckweed had been used only in commercial applications to treat wastewater in North America. In 1989 staff of a non-governmental organization based in Columbia, Maryland, The PRISM Group, initiated a pilot project in Bangladesh to develop farming systems for duckweed and to test its value as a fish feed. An earlier project in Peru investigated the nutritional value of dried duckweed meal in poultry rations.

The results of the pilot operations were extremely promising; production of duckweed-fed carp far exceeded expectations, and dried duckweed meal provided an excellent substitute for soy and fish meals in poultry feeds. Duckweed could be grown using wastewater for nutrients, or alternatively using commercial fertilizers.

During start-up of the pilot operations it also became apparent how little is known about the agronomic aspects of producing various species of the duckweed family, and exactly why it is so effective as a single nutritional input for carp and other fish.

Although these pilot operations were located in South Asia and Latin America, the results suggested that the plant would be important as a source of fish and poultry feed and simultaneously as a wastewater treatment process in selected areas of the Middle East, particularly in Egypt and Pakistan.

Technical and agronomic information about duckweed culture and feed use, and details of farming duckweed and fish in a single system, are not easily available to the general public, let alone to fish farmers in developing countries. The pilot operations in Bangladesh demonstrated that duckweed and fish culture can succeed commercially, although such ventures would initially require technical assistance and information. In many other areas of the world pilot operations linked to applied research may be required to review production parameters before commercial operations should be initiated. This Technical Study was therefore designed to bring together, in one publication, relevant information on duckweed culture and its uses to make people worldwide aware of the potential of this plant, to disseminate the currently available technical and agronomic information, and to list those aspects that require further research, such as duckweed agronomy, genetics and use in animal feeds.

This Technical Study is aimed at the following audiences: (a) established fish farmers who would like to experiment with duckweed as a fish feed, and staff of agricultural extension services involved in fish culture; (b) scientists of aquaculture research institutes who may initiate pilot operations and applied research on duckweed; (c) staff of bilateral and multilateral donor agencies who may promote funding for duckweed research and pilot operations; and (d) wastewater specialists in governments and donor agencies who may promote wastewater treatment plants based on duckweed in conjunction with fish culture.