Ali et al. (2003) classified the compensatory growth into threetypes based on mean final weight: overcompensation, full com-pensation and partial compensation. Overcompensation occurswhen the animals that are submitted to stress conditions achievea greater size at the same age than animals that are not stressed.Full compensation is when animals eventually achieve the samesize at the same age as the control treatment. Partial compensa-tion is when animals fail to achieve the same size at the same ageas the control treatment, but they do show relatively rapid growthrates after being restocked. In the present study, shrimp nursedat 21◦C reached the mean final weight of those nursed at 24◦C,27◦C and 30◦C at the end of Trial 2 (see Table 4). Thus, the com-pensatory growth observed in the 21◦C (30◦C) treatment wouldbe classified as a full compensation in relation to the 24◦C (30◦C),27◦C (30◦C) and 30◦C (30◦C) treatments. However, when the 21◦C(30◦C) treatment is compared with the 33◦C (30◦C) treatment, thecompensatory growth would be classified as a partial compensationbecause the mean final weight of shrimp nursed at 33◦C remainedsignificantly higher than the shrimp nursed at 21◦C at the end ofTrial 2 (Table 4).The results obtained in this study indicate that when the nurs-ery phase of F. brasiliensis is conducted at temperatures below27◦C (e.g., 21◦C), shrimp do not grow as fast as those nursed at27◦C. However, when temperature is increased after the nurseryphase, the weight of shrimp previously nursed at low temperaturesmay be equal to those shrimp nursed at an optimal temperature,due to the compensatory growth. These results have an importantapplication for the production of F. brasiliensis in subtropical or tem-perate regions, such as southern Brazil, where the growing seasonis limited by low water temperatures during the periods prior tostocking and after harvest. The nursery phase would be conductedduring the last month of spring, at temperatures below 27◦C andabove 21◦C for subsequent restocking (grow-out phase), when theenvironmental temperature is increasing at the beginning of thesummer. This strategy would eliminate the need to heat the waterand most likely decrease the production cost. Therefore, furtherstudies are required to evaluate the physiological effects of lowtemperatures on F. brasiliensis, as well as the economic viability ofthis strategy of shrimp production.
5. Conclusions
F. brasiliensis nursed at 27◦C in a super-intensive biofloc-dominated system showed better growth performance, includinghigher productivity, faster growth and higher survival. However,the nursery phase of F. brasiliensis may also be conducted at lowertemperatures, which will ensure high survival at the end of thisphase and compensation of growth when temperature is increased.
Acknowledgments
The authors are grateful to The Ministry of Fisheries andAquaculture (MPA), Brazilian Council of Research (CNPq) and Coor-dination for the Improvement of Higher Level Education Personnel(CAPES). L.H. Poersch and W. Wasielesky received productivityresearch fellowship from CNPq.
Ali et al. (2003) classified the compensatory growth into threetypes based on mean final weight: overcompensation, full com-pensation and partial compensation. Overcompensation occurswhen the animals that are submitted to stress conditions achievea greater size at the same age than animals that are not stressed.Full compensation is when animals eventually achieve the samesize at the same age as the control treatment. Partial compensa-tion is when animals fail to achieve the same size at the same ageas the control treatment, but they do show relatively rapid growthrates after being restocked. In the present study, shrimp nursedat 21◦C reached the mean final weight of those nursed at 24◦C,27◦C and 30◦C at the end of Trial 2 (see Table 4). Thus, the com-pensatory growth observed in the 21◦C (30◦C) treatment wouldbe classified as a full compensation in relation to the 24◦C (30◦C),27◦C (30◦C) and 30◦C (30◦C) treatments. However, when the 21◦C(30◦C) treatment is compared with the 33◦C (30◦C) treatment, thecompensatory growth would be classified as a partial compensationbecause the mean final weight of shrimp nursed at 33◦C remainedsignificantly higher than the shrimp nursed at 21◦C at the end ofTrial 2 (Table 4).The results obtained in this study indicate that when the nurs-ery phase of F. brasiliensis is conducted at temperatures below27◦C (e.g., 21◦C), shrimp do not grow as fast as those nursed at27◦C. However, when temperature is increased after the nurseryphase, the weight of shrimp previously nursed at low temperaturesmay be equal to those shrimp nursed at an optimal temperature,due to the compensatory growth. These results have an importantapplication for the production of F. brasiliensis in subtropical or tem-perate regions, such as southern Brazil, where the growing seasonis limited by low water temperatures during the periods prior tostocking and after harvest. The nursery phase would be conductedduring the last month of spring, at temperatures below 27◦C andabove 21◦C for subsequent restocking (grow-out phase), when theenvironmental temperature is increasing at the beginning of thesummer. This strategy would eliminate the need to heat the waterand most likely decrease the production cost. Therefore, furtherstudies are required to evaluate the physiological effects of lowtemperatures on F. brasiliensis, as well as the economic viability ofthis strategy of shrimp production. 5. ConclusionsF. brasiliensis nursed at 27◦C in a super-intensive biofloc-dominated system showed better growth performance, includinghigher productivity, faster growth and higher survival. However,the nursery phase of F. brasiliensis may also be conducted at lowertemperatures, which will ensure high survival at the end of thisphase and compensation of growth when temperature is increased. AcknowledgmentsThe authors are grateful to The Ministry of Fisheries andAquaculture (MPA), Brazilian Council of Research (CNPq) and Coor-dination for the Improvement of Higher Level Education Personnel(CAPES). L.H. Poersch and W. Wasielesky received productivityresearch fellowship from CNPq.
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