Study on the Bycatch of Shrimp Trawl Fishery in the Waters of Kaoping Canyon

The waters around Kaoping Canyon is an important fishing ground for shrimp trawl fishery in Taiwan. There were four shrimp trawl fisheries operating in this areas namely, the sergestid shrimp mid-trawl, planktonic shrimp mid-trawl, bottom shrimp trawl and shrimp beam trawl. This study was carried out to investigate the bycatch status in situ of these four shrimp trawl fisheries. The bycatch rate were from 65.85% to 93.77% for these four shrimp trawl fisheries. The shrimp beam trawl fishery had the highest bycatch rate while those of the other three shrimp fisheries were less than 76.3%. Among the top four categories of bycatch, the fish was the dominant bycatch in the four shrimp fisheries (44.71-60.56%). The ratios of bycatch to target species were 1.93-15.08 for the four shrimp fisheries. The shrimp beam trawl fishery had the highest ratio and those of the others were less than 3.3. The major bycatch species of sergestid shrimp mid-trawl and planktonic shrimp mid-trawl was Trichiurus lepturus, while the Harpadon microchir and Gerres filamentosus were the main bycatch species for bottom shrimp trawl and shrimp beam trawl, respectively. The top five bycatch species occupied over 50% of the whole bycatch amount of the four shrimp trawl fisheries. A total of 175, 120, 136 and 149 species were caught by sergestid shrimp mid-trawl, planktonic shrimp mid-trawl, bottom shrimp trawl and shrimp beam trawl, respectively. A total of 347 and 379 species were bycatch species and total catch species, respectively.