Zoological Studies

Vol. 46 No. 1, 2007

The Spatial and Temporal Distribution Patterns of the Argentine ShortFinned Squid, Illex argentinus, Abundances in the Southwest Atlantic and the Effects of Environmental Influences

Chih-Shin Chen1,*, Tai-Sheng Chiu2, and Wen-Bin Haung3

1Institute of Fishery Biology, College of Life Science, National Taiwan University, Taipei 106, Taiwan
2Institute of Zoology, College of Life Science, National Taiwan University, Taipei 106, Taiwan
3Institute of Biological Resources and Technology, National Hualien University of Education, Hualien 970, Taiwan

Chih-Shin Chen, Tai-Sheng Chiu, and Wen-Bin Haung (2007) The spatial and temporal distribution patterns of the Argentine short-finned squid, Illex argentinus, abundances and relationships between the squid abundance and environmental variables in the Southwest Atlantic were analyzed using a geographical information system and statistical methods. The abundances of squid were estimated by standardizing commercial catch per unit effort (CPUE) data from the Taiwanese squid fishery during 1986-2003. Illex argentinus has a clear general annual migration pattern, which consistently occurred in different years. The monthly distribution patterns of sea surface temperature (SST) corresponded to the current systems in the Southwest Atlantic. Local squid abundances showed a negative correlation with SSTs during Mar.-Aug., although it was difficult to determine if this reflected any causal link. The Southern Oscillation Index (SOI) and SSTs on the southern and northern portions of the Patagonian Shelf were analyzed to investigate the teleconnection between them and a lag-effect on squid abundances. SSTs on both the southern and northern portions of the Patagonian shelf showed a link with the SOI, at respective lag times of 2 and 3 yr. No significant correlation was found between the SOI and squid abundances, or between SSTs of the southern portion of the Patagonian Shelf and squid abundances within the calculated range of the time lag (10 yr), while SSTs of the northern portion of the shelf were negatively correlated with squid abundances with a lag of 1 yr. Cold events on the northern portion of the Patagonian Shelf in the previous year could be a key factor for the high squid abundance in the current year. Whether or not there are high or low abundances, the distribution patterns of squid on the Patagonian Shelf are locally influenced by the presence of thermal fronts, which are themselves dependent upon the distribution and strength of the cold currents.

Key words: Illex argentinus, Squid abundance, Environmental influence, SST, Southern Oscillation Index (SOI).

*Correspondence: Tel: 886-2-33664549. Fax: 886-2-23639847. E-mail:ccshin@ntu.edu.tw