|Aquaculture - Training Manual (Peace Corps, 1990, 350 p.)|
|Chapter eighteen: Program design - week nine|
Total time: 1 hour, 10 minutes
· Summarize the advantages of Oreochromis niloticus as a culture species;
· Discuss a basic, simple plan for managing O. niloticus.
Overview: This is a trainee-facilitated session. It is one of the two "special technical sessions" that is listed in the schedule presented during Part B of the Field Trip Debriefing/Reentry to Training session. Trainee facilitators summarize the characteristics of O. niloticus that have made it the culture species of choice for so many aquaculture programs, and present a simple, basic management scheme that can be used to raise O. niloticus successfully in light of its characteristics.
1. Trainee facilitators review the characteristics that would be desirable in a culture fish. (Refer to the list of characteristics of "the ideal fish" that all trainees made as one of the first steps in developing their management plans). They then compare various tilapiine species, catfish and carp in light of these characteristics. As they do this, it becomes apparent that O. niloticus possesses more of the desired characteristics than most or all of the other species.
2. The trainee facilitators present a very basic, simple management strategy that can be used to successfully raise O. niloticus. Emphasis is placed on how the presented plan takes into account the characteristics of this fish, including the potential problems that are often encountered in culturing it.
3. The trainee facilitators entertain questions and clarify any points of confusion. In concluding, they should acknowledge that, as seen in the last session (Levels of Intensity Assignment WrapUp), there are many management options, and every strategies must be designed to fit the specific situation. However, the plan that they have presented is a foundation; it is the most simple, basic plan that allows a farmer to maintain control (given the special characteristics of this fish), and virtually ensures successful management. There may be some situations that demand that this plan be modified to accommodate them, and other more elaborate or complex plans might be developed, but in a sense they all build on this very basic foundation.
Resources and Materials:
· Blackboard, chalk, eraser
· Newsprint and markers for preparation of visual aids
· Flip-chart stand and/or masking tape
· Other supplies trainee facilitators may request for preparation of visual aids.
· The staff should select two or three trainees to present this session. They should be trainees with good leadership and communication skills who are well respected and credible among their peers. Notify them as early as possible so they can begin preparing the session.
· For the first part of the session that involves reviewing desirable characteristics and comparing fish species in light of those characteristics, suggest that the trainees make a large chart that lists the characteristics to consider on one axis and the species on the other. They can then fill in the information about each characteristics as it applies to each fish. In evaluating characteristics the following should be considered: growth rate, feeding habits, possible feed conversion ratios, ability to utilize plankton blooms, tolerance ranges for various water quality parameters, temperature tolerance, ease of getting fish to spawn, age at sexual maturity, fecundity, hatch rate, fry survival, spawning frequency, dress-out percentage, etc. On the chart mentioned, the information about each category is filled in for each fish. The information on this chart is filled in prior to the presentation.
· On another chart, the characteristics that are desirable are listed on one axis while the species are listed on the other. (For example, instead of saying Growth Rate, it would say Fast Growth Rate, instead of saying Feeding Habits, it will say Omnivorous, etc.). This chart is posted in front of the group without the characteristics and species labeled along the axes, but with the boxes blank. Based on the information provided in the first chart, the trainees can X in the boxes for the fish that "win" in each desirable characteristic category.
· For some characteristics, certain fish will tie, but when the chart is filled in for all categories the O. niloticus (and the O. aureus) will have more X's. The O. niloticus, according to some sources, grows slightly larger and reaches sexual maturity slightly later than O. aureus, though what will probably make the real difference between them is that 0. niloticus is more widely available in many counties.
· The species that should be considered are the ones listed in the sample chart above (for the Saratherodon species, 5. melanotheron could be used if more information is available), plus any other tilapiine species that are known to be common in the countries to which the trainees are assigned. In addition catfish and carp can be added.
· By the time this session takes place, trainees will have probably heard enough from visiting RPCV's and field staff, and from trainer panels, to have realized that O. niloticus is the fish most aquaculture programs promote. The reason for having the trainees go through the process described above is to let them see that there is a good reason for that choice. Even though they may realize in advance what fish they will probably end up selecting, it is important that they believe in the reason for this and not simply see it as dogma.
· The trainers should work closely with the trainee facilitators to help them understand the basic management plan that is to be presented. They will need to understand exactly why each step is important, exactly how the plan takes into account the characteristics of the fish, and exactly why they are being asked to present this plan as the foundation upon which other plans may be built, but for which there is no real replacement.
· The management scheme the trainees should present is as follows. It does not go into detail, and does not address many of the management steps that would be common in raising nearly any fish. The emphasis is on the points that are especially important because of the characteristics and problems with this particular fish.
1. Begin with a clean, dry pond. (Reason: to be sure only the fish that are intentionally stocked are in the pond);
2. Stock young fingerlings of uniform size and age. (Reason: a small fish is not necessarily a young fish. Since tilapia reproduce at a relatively young age, it is important to stock them young in order to get the most growth possible before sexual maturity is reached. By stocking fish at a uniform age, they are more likely to begin reproducing at approximately the same time. By stocking fish at a uniform size competition will be reduced and there is a better chance that fish will be of a uniform market size at harvest).
3. Feed and fertilize as much as possible! (Reason: the objective is to maximize growth before sexual maturity is reached. You want the fish to grow as quickly as they can. Upper limits to this are determined by economics and water quality. The upper limits are not stressed as much as the idea of getting as much feed and fertilizer in the pond as possible because 0. niloticus can tolerate very low oxygen levels, can utilize a plankton bloom, and is omnivorous so can be fed whatever is economically feasible. Practically speaking (especially in terms of aquaculture in developing countries), there is a much greater chance of someone not providing enough nutrients to maximize growth than there is of providing so many nutrients that water quality becomes limiting);
4. Harvest when the first generation of off-spring are large enough to withstand the stress of harvesting and handling. If everything is done right from the very beginning (correct stocking rate was calculated, growth was calculated correctly, fish were fed and pond was fertilized sufficiently), fish will be market size and the pond will be near carrying capacity at the same time that this occurs. (Trainees should be able to list all three of these conditions that one hopes will coincide at the time of harvest, and they should also realize that the first point the one in bold print - is the most critical. Reason: once the fish reproduce, the pond will soon be out of the farmer's control given the nature of tilapia. Leaving the fish in longer is more likely to result in an overcrowded pond than in bigger fish, and the fingerlings will not be as good for restocking because, with several generations getting mixed together and stunted, it will not be possible to ensure that you are stocking young fish or that all fingerlings are the same age.)
5. Harvest the pond completely (put fingerlings to be restocked in a holding pond or tank), and let the pond dry completely before refilling and restocking. (Reason: to be sure you get a clean start for the next cycle. Drying the pond is the one way to be sure there are no fry left in puddles and/or no brooders left alive in the mud).
· Very important: Before this management cycle is discussed with the trainees, the staff should go through it among themselves. Inevitably, staff members will not agree on every point of this cycle. For example, in Zaire volunteers teach farmers to wait until the second generation of fingerlings is viable before harvesting. Another argument might be that if very large fish are required to meet market demands, this plan might not work. Granted, one could argue for many variations on this theme. The point is to provide the trainees with the most basic, most simple plan, given the nature of the fish with which they will be working, that will permit a farmer to succeed in raising them. If the trainees thoroughly understand this foundation and the reasons for each step, they will easily be able to deal with designing variations, based on sound reasoning, to meet the demands of specific situations. If they do not understand this foundation, they will more easily fall into sloppy management, fall for glamorous but usually unfeasible higher-tech approaches to dealing with problems related to reproduction, or will be less likely to uphold the strict standards that many programs are trying to institute. While there are options, there is no replacement for basic good management.
If staff members do not all agree, they should hash it out among themselves before this is ever discussed with the trainees. Once the trainees become involved, the staff must be consistent in supporting what the trainee facilitators present.
· Trainees will be required to demonstrate a thorough understanding of this plan, and of the reasoning behind it, at their final interviews. Although this fact should not be completely spelled out for them (regarding the final interview), it should be made clear to the trainee facilitators that every trainee is responsible for knowing and understanding the plan. They should have, and should project to the group, a strong sense of the importance of this presentation.
· In order to make the presentation as memorable as possible and to reinforce its importance, the facilitators should be encouraged to be creative in designing their session, and dynamic in presenting it. Use of humor, good visual aids, role plays and/or other extension techniques are appropriate. The presentation must be tight enough to fit into the allotted time, but it should have impact.
· This session takes place after the Levels of Intensity Assignment Wrap-Up. The order in which these two sessions are presented is another point that could be argued. In this program, both ways were tried. The reason one might argue that the Levels Wrap-Up should come after this session is that this session presents a foundation while that one takes it a step further to explore more complicated approaches. This makes sense, but it is recommended that the sessions be presented in the order shown here (this session after the Levels Wrap-Up) in order to end with the basic foundation that trainees absolutely must understand to complete the program.