A study was conducted in the transition patterns of fishing ground and the index of fishing efficiency of the commercial Sakura shrimp boats. Sixteen sakura shrimp boats operating in the waters off southwestern Taiwan from November 1990 to August 1991 were sampled. The center gravity of the fishing ground located on the coastal waters off Fanliao to Fanshan from early November 1990 to middle February 1991; off Tungkang from late May to early July; and off Tungkang to Fanshan from early March to middle May 1991. The relationships between the index of fishing efficiency (F), the gross tonnage (T), and the main engine power (H) of eight sakura shrimp boats were formulated as follows: F = 3.113×10-7 T4.264, r = 0.974 and F = 6.451×10-8 H2.758, r = 0.977.
The index of fishing efficiency was closely correlated with tonnage or engine power. The increasing rate of indices was damped in proportion to tonnage or engine power. Moreover, the index of fishing efficiency was very low when the tonnage of Sakura shrimp boats was below 27 tons or when the main engine power was below 300 HP.