GEOGRAPHICAL RESEARCH ›› 2004, Vol. 23 ›› Issue (1): 1-9.doi: 10.11821/yj2004010001

• Earth Surface Processes •     Next Articles

Study on spatial patterns of Ommastrephes Bartrami Fishing Ground in the Northwest Pacific Ocean

SHAO Quan-qin, RONG Kai,MA Wei-wei, WANG Wen-yu, YOU Zhi-min   

  1. Institute of Geographic Sciences and Natural Resources Research, CAS, Beijing 100101,China
  • Received:2003-07-08 Revised:2003-11-24 Online:2004-02-15 Published:2004-02-15

Abstract:

This article focuses on the analysis of the relationship between Ommastrephes bartramifishing ground and marine environmental factors. Based on daily catch data of Ommastrephes bartrami during 1995 to 2000 by China fishing boats and SST isoline chart covering 1995 to 2000 issued every 3 days by Japan Fisher Information Service Center. ArcGIS was used to store, manage and analyze the data. All the catch data were processed and spatialized to display their spatial distribution. The fishing grounds were identified interactively from the catch data maps. Matching Ommastrephes bartrami fishing ground with SST isoline map revealed that the relationship between them could be divided into 3 main patterns and 16 subclasses. The fishing ground in patternⅠis distributed on the tongue of Kuroshio and Oyashio branches, hence called as tongue type. PatternⅠcan be further classified into 5 subclasses,i.e., warm tongue type, cold tongue type, warm tongue + cold tongue type, warm tongue + cold tongue+ warm tongue type, and warm tongue + cold tongue+ warm tongue + cold tongue type. PatternⅡis located on the branch of Kuroshio or Oyashio, so called as branch type. In patternⅡ, five subclasses can be defined,i.e., warm branch type, warm branch + cold tongue type, warm branch + cold tongue+ warm branch type, cold tongue+ warm branch + cold tongue type, and warm tongue+ cold branch. Pattern Ⅲ is distributed on eddy caused by Kuroshio branch encountering Oyashio branch, also named as eddy type. Pattern Ⅲ can be ulteriorly classified as warm eddy type, warm eddy + cold tongue + warm eddy type, warm eddy + cold tongue (branch) + warm tongue type, warm eddy + cold tongue type,warm eddy + cold tongue + warm branch + cold tongue + warm branch type,and warm eddy + cold tongue + warm branch type. Statistical analyses of 239 samples indicate that pattern III has the highest occurrence frequency and highest catch, and pattern II has the lowest occurrence and lowest production. Subclass 35 has the highest occurrence frequency, and subclass 14 has the highest catch. The average CPUE of pattern Ⅲ is the highest, patternⅠthe lowest.Subclass 31 has the highest CPUE value. In 1995 and 1996, patternsⅡ and Ⅲ dominate. In 1997, pattern Ⅲ dominates. From 1998 to 2000, patternⅠis in domination. In August, patternⅡis in domination. In September, patternⅠdominates. In October, patternsⅠand Ⅲ are in domination. In November, patternⅢ dominates. The SST in patternⅠ usually falls between 15℃and 21℃,patternⅡ,17~24℃, and patternⅢ,10~18℃. The temperature grade in the patternⅠchanges slowly, while pattern Ⅲ, has a big grade change. PatternⅠis mainly located on Kurushio branches 3 and 4, patternⅡon Kurushio branches 2 and 3,and pattern Ⅲ mainly located on Kurushio branches 1 and 2.

Key words: Northwest Pacific, Ommastrephes bartrami, fishing ground, spatial pattern