TITLE:
Clockwise Loops and Anticlockwise Loops Observed in a Stock-Recruitment Relationship
AUTHORS:
Kei Tanaka, Naoki Suzuki, Kazumi Sakuramoto
KEYWORDS:
Stock Recruitment Relationship, Clockwise Loop, Anticlockwise Loop, Age at Maturity, Japanese Sardine, Japanese Anchovy, Chub Mackerel
JOURNAL NAME:
Open Access Library Journal,
Vol.4 No.6,
June
19,
2017
ABSTRACT: Loop-shaped trajectories
are commonly observed in the stock recruitment relationship (SRR). A mechanism
has been proposed that explains why the loops emerge in SRR. The aim of this
study is to validate the mechanism using data for the stocks of 24 fish species
that live in the waters around Japan. The following three questions are
examined: 1) whether or not loop shapes are detected in SRRs for all 24 stocks;
2) whether or not the direction of the loops, i.e., clockwise or anticlockwise, changes depending on the age at
maturity; and 3) whether or not the slope of the regression line adapted for
SRR changes depending on the age at maturity. The results were as follows: 1)
loop shapes in SRR were recognized for all 24 stocks analyzed in this study; 2)
clockwise loops were dominant when the age at maturity was low, and
anticlockwise loops were dominant when the age at maturity was high; 3) the
slope of the regression line adapted for SRR has a negative relationship to the
age at maturity. When the age at maturity was low, the slope was positive but
less than unity. When the age at maturity was high, the slope had no trend and
was recognized as statistically zero. These findings will drastically change
the concept of SRR. All previous findings obtained by analyzing the SRR may be
better to revise essentially.