Aquaculture

An Introductory Text

Robert R Stickney

• Éditeur: CAB International
• Année: 2016
• ISBN:
  9781786390127
• Édition: 3
• Sujet: Technologie et ingénierie
• Sous-sujet: Pêche et aquaculture

Providing a broad and readable overview of the subject, this updated third edition of Aquaculture: An Introductory Text covers issues associated with sustainable aquaculture development, culture systems, hatchery methods, nutrition and feeding of aquaculture species, reproductive strategies, harvesting and many other topics. While its main focus is on the culture of fish, molluscs and crustaceans for food, the book also covers other forms of aquaculture, such as the production of seaweeds, recreational fish and ornamental species, and live foods such as algae and rotifers that are used to feed larval shrimp and marine fish. Thoroughly updated and revised, the third edition of this essential textbook now includes:- Increased coverage of species under culture- Increased scope to cover species for enhancement, recreational fishing, commercial fishing and aquaria- Newly developed culture systems- Information on predictive impacts of climate change- Updated aquaculture production statisticsAquaculture remains one of the most rapidly growing agricultural disciplines and this book remains an essential resource for all students of aquaculture and related disciplines.

1 General Overview of Aquaculture

Definitions

What is aquaculture?

Aquaculture can be defined in a number of ways. The one I have used for many years is: aquaculture is the rearing of aquatic organisms under controlled or semi-controlled conditions. That is a fairly simple, but comprehensive definition. An abbreviated definition is that aquaculture is: underwater agriculture. The longer of the two definitions can be broken down into three major components:

• Aquatic refers to a variety of environments, including fresh, brackish, marine and hyper­saline waters. Each environment is defined on the basis of its salinity (most simply the amount of salt that is dissolved in the water). Salinity is discussed in some detail in Chapter 4.

• Aquatic organisms refers to any organisms that live or can live in water. A branch of aquaculture called mariculture is reserved for aquatic organisms reared in saltwater (which can range from low to hypersaline water). Aquaculture organisms of interest with regard to human food include a wide variety of plants, invertebrates and vertebrates. In the plant kingdom, we include algae along with higher plants and, in some cases, terrestrial plants that are grown using a method called hydroponics or aquaponics (discussed in Chapter 9).

• Controlled or semi-controlled refers to the fact that the aquaculturist is growing one or more types of aquatic organisms in an environment that has been altered to a greater or lesser extent from the environment in which the species is normally found. The amount of control that is exerted by the aquaculturist can vary significantly. Spreading oyster shell on the bottom of a bay to provide a surface for settlement of larval oysters is at one extreme, while operation of an indoor hatchery that incorporates a water-reuse system is at the other (see Chapter 3).

The oyster example would fit the definition of extensive aquaculture where the culturist has little control over the system but merely provides a more suitable habitat for the animals; in this case the spreading of oyster shell. The larval oysters (called spat) may come from natural spawning or may be produced and settled on oyster shell (cultch) in a hatchery, which increases the level of interaction between the culturist and the target species and thus modifies the level of intensity in the overall production process.

When operating a recirculating system, the aquaculturist exerts a high level of control and the system is called intensive. Even just placing a culture unit in the environment represents a means of controlling the animals that are being reared. Cages and net pens are examples (see Chapter 3). There are a number of other approaches that lie somewhere in between the extremes of extensive and intensive. Those are often referred to as semi-intensive systems. Systems that go beyond intensive are called hyperintensive; so we can view aquaculture approaches as ranging broadly from very simple to highly complex, or – perhaps more precisely – as ranging from systems that employ little technology to those that rely heavily upon technology. It can be argued that, as the amount of technology involved in the culture system increases, so does the amount of control that the culturist has over the system. One can also argue that as the level of technology employed increases, so does the probability of system failure, since there are more things that can, and often will go wrong as you add complicated mechanics, work in harsher and harsher environments (like in the open ocean) and add electronic systems (automatic feeders, water quality monitoring, alarm systems, etc., discussed later in this volume). Persons who engage in aquaculture may be called aquaculturists, independent of the type of water system that is employed, or mariculturists, who work with aquatic species in saline environments (from low salinity to hypersaline waters). Depending upon the type of organism(s) being reared, the culturist may also be referred to as a fish farmer, shrimp farmer, clam farmer, etc., or by an even more limited restrictive title, such as rainbow trout producer, catfish farmer, Atlantic halibut farmer, etc.

As you read this book, you will run into the word seafood periodically. When I use that word, you need to think in terms of all edible aquatic species, not just those that are captured from, or cultured in, saltwater. When you think about it, seafood restaurants usually serve both marine and freshwater species. There are exceptions, of course, but in general, a mixture of marine and freshwater species is typical. So seafood includes finfish, invertebrates and often algae (such as in sushi wrappers, salads and various other dishes).

While the above definitions are fairly simple, they embrace an extremely broad and complex topic that involves a broad array of scientific disciplines and business management, along with engineering, economics, accounting and trade skills. A serious student of aquaculture should have experience (and preferably have taken formal courses) in mathematics, chemistry (through at least organic), physics, biology, business management and economics and, if possible, some basic engineering. Mechanical engineering is certainly beneficial and courses in such subjects as hydrology and sanitary engineering can be useful. For many practising aquaculturists, including those involved in certain types of research, the ability to drive trucks and tractors and having some skills in association with plumbing, electrical wiring, welding, painting and carpentry are beneficial, if not required. Experience pouring concrete will also often come in handy. A list of skills and disciplines which are often useful to aquaculturists and that reiterates what you have just read is shown in Box 1.1. A high level of expertise in each of the items on the list is not required, though familiarity with the majority of them will certainly be of value. I should point out that there are a number of those disciplines in which I did not/do not have much, if any, background. In fact, there were no courses in general aquaculture available where I went to college. You probably will not be able to begin a career in aquaculture having had all the background you need, but you will quickly acquire the knowledge and/or skills you need or you will surround yourself with a complement of people who have the skills you lack. If you do not, it could be a difficult uphill battle to become successful. One thing you should take away from this book is that aquaculture is not a science or a discipline that stands on its own. It is made up of many disciplines that come together and are required if a venture is to become economically viable. An important attribute of the successful aquaculturist is also a high level of common sense.

Box 1.1.

A sampling of the skills and disciplines that are often of considerable value to the aquaculturist.

Skills:	Plumbing
	Carpentry
	Welding
	Electrical wiring
	Computer (word processing, spreadsheets, control systems)
	Painting
	Concrete pouring and finishing
	Operating equipment such as tractors, backhoes, bulldozers
	Truck driving (pickup trucks and larger)
Courses:	Business management (bookkeeping, accounting, marketing)
	Basic economics
	Chemistry (particularl...