aquaculture

Patrick Lavens and Patrick Sorgeloos, from the Laboratory of Aquaculture and Artemia Reference Center at the University of Ghent, in Belgium have edited a technical paper entitled Manual on the Production and Use of Live Food for Aquaculture. It is available as a free download.

The topics comprehensively covered include micro algae, rotifers, artemia, zooplankton, cladocerans (daphnia and moina), nematodes and trochophora larvae.

From the introduction:

Whereas in the 1970s the production of farmed marine finfish and shrimp relied almost exclusively on the capture of wild fry for subsequent stocking and on-growing in ponds, tanks or cages, the complete domestication of many marine and brackishwater aquaculture species was only achieved during the last two decades. However, since then the controlled production of larvae from captive broodstock, or in other words the hatchery production of fry, has now become a routine operation for most cultivated fish and shellfish species; billions of fish and shellfish larvae (i.e. bivalve molluscs, penaeid shrimp, salmonids, European seabass, Gilthead seabream etc.) currently being produced within hatcheries all over the world.

The cultivation of larvae is generally carried out under controlled hatchery conditions and usually requires specific culture techniques which are normally different from conventional nursery and grow-out procedures, and especially with respect to husbandry techniques, feeding strategies, and microbial control. The main reason for this is that the developing larvae are usually very small, extremely fragile, and generally not physiologically fully developed. For example, their small size (ie. small mouth size), the uncompleted development of their perception organs (ie. eyes, chemoreceptors) and digestive system, are limiting factors in proper feed selection and use during the early first-feeding or start-feeding period. Moreover, in species such as shrimp, these are not the only problems as the developing larvae also have to pass through different larval stages, eventually changing from a herbivorous filter feeding behaviour to a carnivorous hunting behaviour. It is perhaps not surprising therefore that larval nutrition, and in particular that of the sensitive first-feeding larvae, has become one of the major bottlenecks preventing the full commercialization of many farmed fish and shellfish species.

Ruben Manik, writing in Formulated Feeds for Freshwater Prawn: The so-called giant freshwater prawn, Macrobrachium rosenbergii, is widely distributed in the Indo-Pacific region, ranging from Australia to New Guinea to Indus River delta. This species has emerged in the last few years as one of the aquatic animals having a very high potential for aquaculture.

This is based on a number of advantages of this species over many other crustaceans. It adapts to a relatively wide range of temperature from a minimum of 15 to a maximum of 35°C. This species has a relatively short larval life. It is also a fast growing species. Fast growing individuals reach market size in about 7–8 months, and the meat is of high quality in terms of tests and texture.

Food is normally the largest single item in the running expenditure of a prawn hatchery or prawn farm. If prawns are held in artificial confinement where natural food are absent or limited, an external food source should be added. For example, the external food of freshwater prawn larvae that are held in tanks may consist of live food (nauplii of brine shrimp) or artificial food (fish egg, fish flesh, formulated feeds, etc.)

The production of freshwater prawn stocked in pond depends on the ability of the environment to produce natural food. Various factors such as soil and water fertility, water temperature and intensity of solar radiation affect the production level of natural food in the pond. However, for maximum rate of performance, the supplemental feeding programme is supposed to be important. Hence, the knowledge of nutrient requirements, the preparation of suitable feeds from the local available ingredients, feeding techniques, and the cost effectiveness of prepared feeds is of paramount importance to commercial success.

The FOA have published a free report from November 1986 (available online) on the Optimum Dietary Protein Requirement for Macrobrachium rosenbergii Juveniles, by Jocelyn L. Antiporda, a Research Associate from the Southeast Asian Fisheries Development Center (SEAFDEC – AQD), (Binangonan Research Station, Binangonan, Rizal Philippines 3106).

Abstract: The dietary protein requirement of M. rosenbergii juveniles was determined in growth trials performed in indoor aquaria using rations based on fish meal and shrimp meal as the main sources of protein. Five protein levels from 20 – 40% at 5% interval were tested to assess the best growth. Mean body weights and lengths of 4 replicate treatments were subjected to analyses of variance in determining differences between protein levels. Results showed no significant differences in all variables considered. Under this laboratory feeding experiment, the prawns attained weights of 0.95 g (994% gain), 0.94 g (921% gain), 1.3 g (1417% gain), 0.95 g (996% gain) and 1.17 g (1263% gain) for 20%, 25%, 30%, 35% and 49% crude protein levels, respectively in 89 day-culture period.

From the introduction:

One of the major factors limiting the economic success in any commercial culture of a species is the food requirement. Shang and Fujimura (1977) estimated feed cost to account for about 13 – 27% of the total annual cost of production. Protein, being an important dietary constituent among animals, directly influence the formulation of diets and consequently affect the cost of production. Accumulated knowledge on the nutrient requirements of the prawn is limited and the lack of standard techniques among researches resulted to wide variations of findings thereby making direct comparisons difficult. Most of the available data relating prawn growth and dietary protein levels have been reviewed by Forster (1976), New (1976) and Wickens (1976). Data on the nutritional requirements of M. rosenbergii are scarce. Several workers have tried to develop artificial diets capable of sustaining good growth using a variety of foodstuffs (Kanazawa, et al., 1970; Cowey and Forster, 1971; Deshimaru and Shegino, 1972; Sick et al., 1972; Andrews et al., 1972; Forster, 1972; Balazs et al., 1973). Studies by Weidenbach (1982) confirmed that prawns ingest commercial pellets when available and that prawns also utilize available vegetation regardless of the presence of commercial pellets. Among the foodstuffs used, flesh of molluscs and crustaceans were found the most acceptable, producing the best growth especially among the marine prawns (Deshimaru and Shegino, 1972; Forster and Beard, 1973). Deshimaru and Shegino (1972) stated that marine prawn growth correlates with the amount of crude protein in the diet and that diets having crude protein above 60% showed high feed efficiency as a rule.

A free version on Huxley’s classic book The Crayfish is maintained on online by Rich Palmer, at the University of Alberta.

The book is subtitled: ‘An introduction to the study of zoology’. I particularly enjoy the ‘kinder, gentler’ writing style and it feels (or perhaps more accurately – reads) as though Huxley is very attuned to a more holistic approach to describing the crayfish.

The online version is supported by the original elegant woodblock illustrations and, as well, Rich has created a glossary (which was not part of the orginial edition).

Backyard Aquaculture in Hawaii: A Practical Manual by James Szyper, Ph.D., is available as a free .pdf download.

This large document (93 pages), is written for the beginning aquaculturist. It focuses which plants and animals to grow, and how to grow them with a minimum investment in land and equipment. The basics are covered, and then there’s added value with information on such subjects as pond management and water recycling. The manual has numerous valuable tables and drawings. While this manual is written to be an effective guide to backyard aquaculture for Hawaii, the principles hold true anywhere.

In this book, the terms “backyard” and “small-scale” generally refer to systems larger than home aquariums, but no larger than ponds of about one acre, a size range that takes in many possibilities. Many excellent books on aquarium-keeping are available for people with that interest, and a great number of works have been written on large-scale commercial aquaculture.

This book will provide a starting point and information source for individuals interested in learning more about backyard aquaculture, or in starting up a small-scale culture system. It will present information to help you decide whether this kind of activity will be possible and enjoyable for you; suggest an orderly approach to maximize your chances for success; present some detail on how to accomplish necessary tasks and start up some specific culture systems; and serve as a source of reference materials for further or more detailed reading.

Following on from a posting back in August 2005, gender issues in aquaculture, it’s clear women are playing a strong role in aquaculture. Australian Women in Agriculture have a link to Mary Nenke, the Manager/Proprietor of Cambinata Yabbies; and from another source, Milada Safarik is one of the principals of Aquabait, a company involved in the farming of marine worms for the fishing bait industry.

The FAO report on a workshop on Women in Aquaculture held in Rome in 1987.

The Assessment of Women Achievers in Aquaculture Workshop was held in 2004, in Charente-Maritime (Rochefort – near La Rochelle), France with the financial support of the Directorate-General Fisheries of the European Commission.

Despite these initiatives, conditions in the Third World are as challenging as ever. A. Shaleesha and V. A. Stanley report in Involvement of Rural Women in Aquaculture: An Innovative Approach that although women have proved to be competent in adopting new aquaculture technologies, their role is very much restricted and often ignored. One of the major reasons is the location of aquaculture sites and several sociocultural taboos against women who strive to earn for their family’s subsistence in rural areas. There is a gender bias in many aquaculture activities. To ensure that women utilize their full potential in profitable activities like aquaculture, it is necessary to provide capacity building support to rural women, which will eventually lead to their empowerment. In countries like India, the technology provided to women must take into account cultural aspects. One such project – backyard ornamental fish breeding and management – has been found to offer immense scope for improving the livelihood of rural women. This paper gives some practical tips for dissemination of technology in the rural sector, particularly to rural women.

An excellent case study on how seaweed farming helps women in Tanzania outlines how quite simple efforts can make a positive impact in household incomes and become literally life changing.