Aquaculture is gradually moving toward Open Ocean Fish Farming (OOFF) in recent times because of the huge environmental impacts caused by onshore fish farming. Although Offshore fish farming has a lot of benefits over onshore fish farming it has its threats as well. Harmful Algae Blooms (HAB) are one such threat to Offshore fish farming. HAB is the formation of algae in groups that are toxic. The HAB can significantly affect the health of the fish that are being cultured. To prevent and act on HAB, monitoring of different environmental parameters is done in the field that is of concern. Traditionally for these kinds of monitoring human drivers are employed. But involving human drivers for monitoring in offshore conditions is cost expensive and difficult. Technology-enabled autonomous monitoring is needed in an offshore environment. Here comes underwater Wireless Sensor Networks (UWSN) which can be used for inspection of underwater fish farms for the detection of HAB. In UWSN loss is one of the main parameters that affect the Quality of Service. So this research focuses on the development of a Stochastic Network Calculus (SNC) based mathematical model of the network layer design for underwater communication that can be used in OOFF. In this work, we introduced the loss factor parameter into SNC and derived the loss bound for underwater communication, and the same is evaluated using discrete event simulation.