STATIONAL VARIABLITY IN ENZYMATIC ACTIVITY OF WILD-TYPE Paralabrax nebulifer (TELEOSTEI: SERRANIDAE) FROM THE GULF OF ULLOA, B.C.S., MÉXICO

Barred sand bass (P. nebulifer) is a very important comercial resource for the northwest fishing communities in Baja California Sur, along with the lobster and abalone fisheries. However, few studies have been made regarding trophic carachteristics of the species, such as digestive enzymatic activity. Variablity of enzymatic activity may show insights about the physical and biological factors influencing nutrition. These interactions are useful especially in this species whose aquaculture potential is being currently developed.

Fish were captured within well known fishing spots for barred sand bass in the northern part of the Gulf of Ulloa in March 2017, August 2018 and June 2019. A total of 17 fish (10 Male, 7 Female) were captured, with mean total length = 30.65 cm and mean weight = 388.48 g. All of the fish were dissected at the coast; the stomachs were extracted and kept in liquid nitrogen or ice for transport to the Laboratorio de Fisiología Comparativa y Genómica Funcional at CIBNOR. Enzymatic extracts were prepared by homogenizing the whole stomach with cold distilled water. Total enzymatic activity for pepsin was measured by  spectrophotometric methods. All statistical analysis were made with R (version 3.4.4).

Fish length was found to be lower in samples from 2017. Pepsin-like activity was lower in samples from 2019, while total enzymatic activity was found higher in samples from 2018. No significant differences were found between sexes.

Differences in length and enzymatic activity vary from seasonal changes related to barred sand bass spawning season and  trophic conditions, while a distinct dimorphic trait was not found, as it is known within the species.