I explore that South Korea’s major import fishery product markets-frozen hairtail, frozen mackerel, frozen pollock and frozen squid-are integrated by testing whether there is favorable evidence of the law of one price (LOP). Unlike previous studies on the LOP for fishery product markets, I assume non-zero import costs and include them in a trade model. To explore whether LOP holds for major import fishery product markets in South Korea with non-zero import costs, I utilize a non-linear time-series model, Smooth Transition Autoregressive (STAR) model with the sample periods from January in 2002 to December in 2019. I find that the behaviors of home-foreign price (i.e., import price) differentials of all four major import fishery products are non-linear depending on whether trade occurs and favorable evidence of LOP for each import market in South Korea. These findings indicate that each of South Korea’s major import fishery product markets is integrated. They imply that the supply of each major import fishery product-frozen hairtail, frozen pollock, frozen mackerel and frozen squid, and their prices are stable even if there is an economic shock on each market. When it comes to trade policy implications, the Korean trade policy including tariffs or quotas against their import countries for the four major import fishery products may not have influences on their price in the markets.

We explore each of the three major domestic fishery product markets in South Korea- Frozen Squid, Frozen Hair tail and Dried Anchovy- to assess whether we can find evidence for Law of One Price (LOP) across the five major cities- Seoul, Dae-Jeon, Dae-Gu, Gwang-Ju and Busan. To achieve our aim, we utilize two different types of unit root tests: Augmented Dickey-Fuller (ADF) and Kwiatkowski-Phillips-Schmidt- Shin (KPSS) unit root test. In each of the three fishery product markets, we find evidence in support of LOP among several cities, which confirms that these markets are integrated to a certain extent. In particular, we find stronger evidence of LOP for Dried Anchovy market relative to the other two fishery product markets. Based on our findings, we argue that the Dried Anchovy market exhibits a greater degree of market integration across the five major cities in South Korea compared to the other two fishery product markets. The greater degree of market integration in the Dry Anchovy market is facilitated by its higher substitutability across cities; taken together these findings show that the market for Dried Anchovy in South Korea is more efficient than the markets for Frozen Squid and Frozen Hair tail.