Based on the samples collected by Chinese scientific research off the Costa Rica Dome from July to August in 2009, statolith microstructure of the Jumbo flying squid, Dosidicus gigas, was analyzed to study their age, growth and population structure: Three typical growth zones (postnuclear, dark and peripheral zones), abnormal increments (checks) and aberrant microstructure (additional center and additional rings) were found in the statoliths examined.The squid size ranged from 205 to 429 mm dorsal mantle length (ML) with age no more than 10 months for females and 8 months for males.Back-calculated hatching dates were from November 2008 to April 2009 with a peak between January and February (winter).Growth in ML was best described by a linear function for both the sexes, while growth in body weight (BW) was best quantified by an exponential function for females and a power curve for males.The maximum absolute daily growth rates and instantaneous growth rate in ML were reached at 181-210 and 151-180 days for females and males, respectively.The Costa Rica dome and its adjacent waters were considered as a potential spawning ground because of presence of not only high proportion of mature squid but also rhynchoteuthion paralarvae, and high primary productivity from the strong upwelling.