This paper investigates the performance of hybrid dual hop underwater system which has been proposed for monitoring vast region under shallow sea environment. This hybrid underwater opto-acoustic sensor network (UOASN) is designed to provide higher data rates and less propagation delay with respect to traditional acoustic underwater systems, by including optical carrier. An acoustic sensor and an optical sensor are mounted on shallow water floor at different locations that acquire the surrounding information and transmit it continuously to the underwater vehicle based on round-robin scheduling. Such vehicle is comprised of decode-and-forward relaying mechanism. The underwater acoustic link is determined by alpha-F fading distribution and underwater optical link follows the mixture Exponential-Generalized Gamma (EGG) model to characterize channel irradiance fluctuations. The novel closed form expressions for various end to end (E2E) signal to noise ratio (SNR) statistics such as equivalent probability density function (PDF), cumulative distribution function (CDF) and moments have been derived. The analytical expressions are also obtained for outage probability, average bit error rate, ergodic capacity and outage capacity. Besides, the closed form asymptotic expressions for outage probability and average bit error rate are derived.