Patrones de variabilidad intrapoblacional en el crecimiento individual de la vieira patagonica (Zygochlamys patagonica) en el golfo San Matias.

DEL GROSSO, LAURA; MORSAN, ENRIQUE M.

IBMP - Serie Publicaciones

Instituto de Biología Marina y Pesquera "Alte Storni"

Lugar: San Antonio Oeste; Año: 2004 p. 1 - 14

1666-4019

One of the most important pectinid fisheries of the word is developed in Argentinean Continental Shelf for Patagonian scallop, Zygochlamys patagonica. The information about beds in the Gulf San Matias has not been formally reported until 2002, although the existence of beds is well-known from 1986. The objective of this study is to compile the fragmentary existing information, and estimate a model for individual growth of this species within the GSM. Samples of a coastal bed (NE coast, 50 and 75 m of depth) collected in period 1986-1990 were analyzed, and new samples were taken from a deeper bed (located to the south of the gulf, 148 m depth). The growth pattern was described using different types of data: - Progression of the size frequency distribution (coastal bed), - Annual increments of size of external bands recorded on the external shell surface (both beds), - Size-at-age data ageing the individuals through marks in the ligament and shell (both beds). Size-at-age data revel significant differences in the individual growth between beds, in the three parameters of the growth model. Asymptotical size in coastal bed was greater than deeper bed. The formation of the growth ring shows discrepancies respect to which it has been described for other populations from Continental Shelf. The results of this study indicate that Z. patagonica records two ring per year after first sexual maturity in beds placed on the NE coast. A summer mark that would correspond at spawning time and a winter mark could be produced by a decrease in the primary productivity affecting growth. On the other hand, under the assumption that the environmental conditions in deeper-southern bed and adjacent Continental Shelf are similar, we suppose that external growth bands recorded in individuals from both places would have the same pattern, i.e. one band per year, recorded during summer.