Extracellular agarase produced by the Pseudoalteromonas strain JYBCL 1 is used in a variety of applications in the biotechnology, pharmaceutical, cosmetic, and food industries. The optimization of culture conditions for agarase-producing microbes and agarase activity is thus an important consideration in many industrial applications. In this study, the optimum medium composition and culture conditions for the JYBCL 1 strain were determined using the "one factor at a time" (OFAT) method and a Plackett-Burman design. Optimal cell growth was obtained at a temperature of $25^{circ}C$ and when 10 g/L tryptone was present in the culture medium. Optimal agarase activity occurred at a temperature of $40^{circ}C$ and at pH 6. The presence of carbonyl groups in the extracellular agarase hydrolysis products was verified using FT-IR. LC-MS identified the hydrolyzates as neoagarohexaose, neoagarotetraose, and neoagarobiose. The extracellular agarase produced by the JYBCL 1 strain used in this study was identified as ${eta}$-agarase by $^{13}C$-NMR spectroscopy.