TY - JOUR
T1 - Morphophysiological studies on alligator gar (Atractosteus spatula) larval development as a basis for their culture and repopulation of their natural habitats
AU - Mendoza, R.
AU - Aguilera, C.
AU - Rodríguez, G.
AU - González, M.
AU - Castro, R.
N1 - Funding Information:
Financial support obtained from CONACyT (grant: 25633-B), SIREYES (grant: 97/6002) and PAICyT (grant: CN026-98) is gratefully acknowledged. The authors wish to express their gratitude to the Aquaculture Production Center “Tancol” from SAGARPA, Tamaulipas for the donation of eggs and larvae samples. The authors are very much indebted to Dr. Allyse Ferrara for her assistance in the preparation of the manuscript and her helpful suggestions.
PY - 2002
Y1 - 2002
N2 - Natural populations of alligator gar (Atractosteus spatula) have declined recently due to the effects of commercial and sport fisheries. Aquaculture represents a short-term alternative to restore natural populations, and a first step to accomplish culture of this species is the study of early life stages. Therefore, multidisciplinary research was used to describe the major morpho-physiological changes taking place during this period. The studies serve as a basis for the introduction of artificial diets for culture. A morphological study distinguished different nutritional stages, as well as external indicators of starvation. A histological approach showed the digestive tract to be completely formed 5 days after hatching (DAH), at the beginning of exogenous feeding. Throughout larval development, intestinal maturation was followed and a nutritional indicator based on the mid-gut cell height was validated. The occurrence of pepsin-like proteolytic activity was detected from five DAH, while trypsin, chimiotrypsin and aminopeptidase-like activities gradually increased from two to nine DAH. The incidence of cannibalism in culture conditions was controlled by exposure to anti-thyroid compounds (thiourea - TU) to retard snout growth. This treatment did not effect growth and allowed juveniles to feed on live prey but prevented the consumption of gar larvae of the same size. Larvae exposed to 3,3',5-triiodo-1-thyronine (T3) had faster development, a potentially advantageous characteristic for the repopulation of their natural habitat. Finally, artificial feeds were well accepted and resulted in growth rates similar to those of gar larvae that were fed natural prey. This has allowed the development of a feeding strategy that effectively reduced cannibalism and led to the production of 30 cm juveniles in four months.
AB - Natural populations of alligator gar (Atractosteus spatula) have declined recently due to the effects of commercial and sport fisheries. Aquaculture represents a short-term alternative to restore natural populations, and a first step to accomplish culture of this species is the study of early life stages. Therefore, multidisciplinary research was used to describe the major morpho-physiological changes taking place during this period. The studies serve as a basis for the introduction of artificial diets for culture. A morphological study distinguished different nutritional stages, as well as external indicators of starvation. A histological approach showed the digestive tract to be completely formed 5 days after hatching (DAH), at the beginning of exogenous feeding. Throughout larval development, intestinal maturation was followed and a nutritional indicator based on the mid-gut cell height was validated. The occurrence of pepsin-like proteolytic activity was detected from five DAH, while trypsin, chimiotrypsin and aminopeptidase-like activities gradually increased from two to nine DAH. The incidence of cannibalism in culture conditions was controlled by exposure to anti-thyroid compounds (thiourea - TU) to retard snout growth. This treatment did not effect growth and allowed juveniles to feed on live prey but prevented the consumption of gar larvae of the same size. Larvae exposed to 3,3',5-triiodo-1-thyronine (T3) had faster development, a potentially advantageous characteristic for the repopulation of their natural habitat. Finally, artificial feeds were well accepted and resulted in growth rates similar to those of gar larvae that were fed natural prey. This has allowed the development of a feeding strategy that effectively reduced cannibalism and led to the production of 30 cm juveniles in four months.
KW - Alligator gar
KW - Enzymes
KW - Hormones
KW - Larval development
KW - Morphology
KW - Nutrition
KW - Physiology
UR - http://www.scopus.com/inward/record.url?scp=0141726748&partnerID=8YFLogxK
U2 - 10.1023/A:1025047914814
DO - 10.1023/A:1025047914814
M3 - Article
AN - SCOPUS:0141726748
VL - 12
SP - 133
EP - 142
JO - Reviews in Fish Biology and Fisheries
JF - Reviews in Fish Biology and Fisheries
SN - 0960-3166
IS - 2-3
ER -