Environmental effects on the abundance distribution of blue marlin (Makaira nigricans) in the Indian Ocean

• Main Authors: Tung-Lin Kuo, 郭東霖
• Other Authors: Sheng-Ping Wang
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/02949434274139188700

碩士 === 國立臺灣海洋大學 === 環境生物與漁業科學學系 === 100 === Generalized linear model (GLM) and generalized additive model (GAM) were applied to examine the relative influence of environmental, spatial, temporal and operational effects on Catch per unit effort (CPUE) of blue marlin in the Indian Ocean for the period of 1995 to 2009 based on the fishery statistics of Taiwanese distant water longline fishery. The trend of standardized CPUE indicated that the abundance declined since 1999, reached a lowest value in 2007, and gradually increased thereafter. The results of GLM analysis indicated that CPUE of blue marlin in the Indian Ocean was significantly affected by the effects of hooks per basket, shear current and thermocline depth. The effects of longitude, Dipole Mode Index, Indian Oscillation Index and temperature gradient were not statistically significant. The results of GAM analysis indicated that high CPUE occurred in the 1st and 4th quarters when Dipole Mode Index was higher, i.e. the surface seawater temperature in the eastern Indian Ocean was relatively colder than that in the western Indian Ocean. In the full moon phase, high CPUE also occurred at the thermocline depth of around 100 m. This study also indicated that high CPUE would concentrated in the waters of northeastern Indian Ocean with longitude of 60E-70E and latitude of 2.5N-12.5N, and in the waters of northwestern Indian Ocean with longitude of 80E-90E and latitude of 2.5N-17.5N. In addition, the distributions of integrating standardized CPUE with shear current and thermocline depth revealed that high CPUE occurred in the waters, where shear current obviously changed from weak to strong, in 1st and 4th quarters. In 3rd quarter, CPUE would be lower in the waters, where shear current changed slightly and thermocline depth was relatively shallow.