ONTOGENY OF DIGESTIVE ENZYMATIC ACTIVITY OF PACIFIC RED SNAPPER Lutjanus peru LARVAE

Renato Peña*, Dariel Tovar-Ramírez, Maurico Contreras-Olguín, Patricia Hinojosa, Silvie Dumas, Laura Flores-Montijo, Roberto Taylor-Cota.
 
Unidad Piloto de Maricultivos.
Centro Interdisciplinario de Ciencias Marinas.
Instituto Politécnico Nacional. Av. IPN s/n. Col. Playa Palo de Santa Rita. C.P. 23096. La Paz, BCS. México.
Tel. +52 (612) 1225344. Fax +52 (612) 1225322.
*rpenam@ipn.mx
 

The Pacific red snapper (Lutjanus peru) (Nichols & Murphy, 1922) is an important species to the fisheries along the Pacific coast of Mexico. In recent years there has been an increasing interest from both the private and public sectors in developing a sustainable culture program for this species as a viable economic alternative in the region. However, larviculture trials of Pacific red snapper have been characterized by very low survival during the first days of development. Therefore, several aspects related to feeding, nutrition, growth and early development have been studied in our laboratory. Recently, the development of the digestive tract was described and now we present the ontogeny of the digestive enzymatic activity. This information will be essential in implementing new feeding schedules, introducing new prey types or selecting the most favorable day for early weaning during larval rearing.

Larvae were obtained from a single hormonally induced spawn of captive broodstock and were transferred and reared in twelve 180-L fiberglass tanks equipped with a seawater recirculating system. Larvae were fed using live prey following a feeding schedule based on live prey. An average of 20 larvae were collected at 3, 8, 11, 15, 18, 22 and 25 days after hatching (DAH). Whole larvae were homogenized (FastPrep-245G), centrifuged (Eppendorf 5430R) at 15.000 x g and 4 °C for 15 minutes and the supernatants were stored at -80 °C until use. Activities of main digestive enzymes were assessed by fluorometry (trypsin, chymotrypsin, amylase, lipase and phosphatases alkaline and acid) and acid proteases by photometry. Readings were performed in triplicate using either a Varioskan flash fluorometer (Thermo Scientific®) or a Jenway 6505 spectrophotometer. Results are expressed in specific and individual activity from three replicates and three measurements.

All enzymatic activities were detected from hatching. An increment in the enzymatic activity with development was observed. Higher individual activities of all enzymes were observed between 18 and 22 DAH, except for amylase. Amylase showed high activity from 3 DAH and a late decrease at 25 DAH. These patterns of enzymatic activity during development have been reported in other marine fish larvae. The decrease of amylase activity and the increment of the other pancreatic enzymes are considered a marker for maturation of the digestive function and a transition to a juvenile-like digestion. In conclusion, total enzymatic equipment for this species is complete between 18 and 25 DAH, suggesting that weaning during larviculture trials of this species may be possible at this early age.