In conclusion, over the last 50 years, the number of vessels, crew members, and production of illegal bottom trawl fishing overtook those of legal trawl fishing due to the following reasons [13]:
(i)
The revenue from illegal trawl fishing was higher than that of legal trawl fishing.
(ii)
Poorly resourced law enforcement could not patrol these vast coastal areas.
(iii)
The monetary penalties levied for illegal bottom trawling were inadequate.
(iv)
The Korean government was afraid of social and political conflict caused by strict enforcement.
(v)
The industry expected that illegal trawl fishing would ultimately be compensated.
As the numbers of illegal bottom trawl vessels increased, the number of enforcement actions also increased. During the ten years from 1996 through 2006, the annual average number of enforcement actions was 3215, among which 69.7% were related to illegal bottom trawl fishing [14]. In 2002 and 2003, the number of enforcement actions was 3102 and 2067, respectively, among which 1258 and 882, respectively, were conducted illegally (Table 4).