Watercress has been cultured and harvested for hundreds of years in many countries around the world. Perhaps due to its familiarity it has been almost ignored as an aquacultural crop – it is seen simply as another species suitable for hydroponic growing – at times simply because an entrepreneur spotted an opportunity – as in this historic watercress farm in Maryland, USA.

According to the Watercress Alliance, watercress has been prized for its food values as well as flavour –

Brimming with more than 15 essential vitamins and minerals, its health giving properties has been known since ancient times. Around 400 BC on the Island of Kos, Hippocrates, the father of medicine, is said to have located his first hospital beside a stream so that he could grow a plentiful supply of watercress to help treat his patients, the Greek general Xenophon made his soldiers eat it to increase their vigour before going into battle and Roman emperors said it enabled them to make “bold decisions.”

The annual Alresford Watercress Festival is held in celebration of the health, nutrition, flavour, historic, and economic virtues of watercress. Further exploration of the properties of the watercress includes a research investigation into the potential of watercress as a superfood. It would be just wrong to not mention the pleasures of cooking with watercress as well.

Watercress (Nasturtium microphyllium, Nasturtium officinale) is a species gazetted for land-based aquaculture in New Zealand. The Australian Rural Industries Research and Development Corporation (RIRDC) have published indicating that larger scale watercress production has potential as a vibrant new production industry catering to the demand for new flavours and healthy foods in Australia. The full report Potential for Watercress Production in Australia is available online. This from the media release:

Watercress plants are aquatic members of the brassica (cabbage) family, and are botanically related to garden cress and mustard — characterized by a peppery, tangy flavour. The vegetable is associated with a range of health benefits and contains significant amounts of iron, calcium and folic acid, in addition to vitamins A and C.

The plants are relatively easy to row, and production systems can be hydroponic or gravel based. While gravel-based production offers more cost-effective mechanized harvesting and handling, hydroponic systems offer greater water-use efficiency.

The RIRDC-funded research collates information useful to potential investors in watercress production and marketing in Australia, including new opportunities for its introduction into Australian diets, both as a flavoursome salad or in new cooked recipes.

It seems possible that the domestic or backyard aquaculturalist has a potential to explore watercress farming – here’s an indication of how it might be achieved from Herbs from Wales. A similar approach using watercress is described at Growing Power in Wisconsin, USA, and for another perspective of the use of watercress as a water filter plant in the same development. In contrast, the Independent (UK) reports of environmental issues for the Bourne, a small chalk river, renown for its trout fishing, having been polluted by a watercress farm.

In general, detailed information about the practical husbandry of watercress is quite difficult. Courtesy of the wayback engine, it is possible to examine an article from a 1947 edition of the Herts (Hertfordshire, UK) Countryside by W. G. S. Crook, J.P. – Down to the Cress Beds. From the article –

Cultivation requires about one person per acre for the whole operation of planting, bunching, washing and dispatching, together with the incidental work of maintaining the ditches. The men are supplied with thigh-length wading boots. During the winter months the cress is kept down in the water as far as possible by the use of heather brooms or wooden rollers as a protection against frost. At this time the crop makes its quickest growth close upon the outlet from the artesian wells, where the temperature of the water is most conducive to growth; at the far end of the ditch it may be very retarded because of the drop in temperature.

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nutritive metals in rainbow trout diets

Nicolas R. Bury, Paul A. Walker, and Chris N. Glover from the King’s College London, School of Health and Life Sciences, have published a report entitled Nutritive metal uptake in teleost fish. From the abstract:

Transition metals are essential for health, forming integral components of proteins involved in all aspects of biological function. However, in excess these metals are potentially toxic, and to maintain metal homeostasis organisms must tightly coordinate metal acquisition and excretion. The diet is the main source for essential metals, but in aquatic organisms an alternative uptake route is available from the water. This review will assess physiological, pharmacological and recent molecular evidence to outline possible uptake pathways in the gills and intestine of teleost fish involved in the acquisition of three of the most abundant transition metals necessary for life; iron, copper, and zinc.

P. Carriquiriborde (from the Environmental Research Centre, National University of La Plata-CONICET, La Plata, Argentina), R. D. Handy, and S. J. Davies (School of Biological Sciences, University of Plymouth, UK), have published a report entitled: Physiological modulation of iron metabolism in rainbow trout (Oncorhynchus mykiss) fed low and high iron diets. From the abstract:

Iron (Fe) is an essential element, but Fe metabolism is poorly described in fish and the role of ferrireductase and transferrin in iron regulation by teleosts is unknown. The aim of the present study was to provide an overview of the strategy for Fe handling in rainbow trout, Oncorhynchus mykiss.

J. Burke and R. D. Handy (again, from the School of Biological Sciences, University of Plymouth, UK), have published a report entitled: Sodium-sensitive and -insensitive copper accumulation by isolated intestinal cells of rainbow trout Oncorhynchus mykiss. From the abstract:

The pathway for copper (Cu) uptake across the mucosal membrane into intestinal cells has not been elucidated in fish. Copper accumulation in freshly isolated intestinal cells from rainbow trout Oncorhynchus mykiss was measured after exposure to 0–800 µmol l–1 CuSO4 for 15 min.

Posted in feeding, freshwater fin fish | 1 Comment

keeping native fish as pets

image of shiner from http://www.ksuaquaculture.org/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.

Update (Dec 2010) – sadly, the Native Fish Conservancy seems to have met an untimely end. The above link is via the Internet Archive. If any of the former webmaster/site managers are out there please feel free to make contact.

Posted in ecosystems, freshwater fin fish, ornamental, web site | 3 Comments

new news

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.

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mud (mangrove) crab

Crab Dinner - Buy at AllPosters.comThe 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.

Posted in crustacea | 3 Comments