TITLE:
Density-Dependent Effect Occurs Regardless of Density
AUTHORS:
Kazumi Sakuramoto
KEYWORDS:
Stock-Recruitment Relationship, Density-Dependent Effect, MSY, Pink Salmon
JOURNAL NAME:
Open Access Library Journal,
Vol.3 No.11,
November
4,
2016
ABSTRACT: Maximum sustainable yield (MSY) is the most important concept in fisheries resource management. MSY can be established based on the concept of the density-dependent effect. However, the concept that a density-dependent effect controls the fluctuation of the population living in the ocean is controversial. This paper discusses the validity of the density-dependent effect focusing on the stock-recruitment relationship (SRR). In many cases, the SRR shows a clockwise or ant-clockwise loop. If we try to explain the population fluctuations using the density-dependent effect, the clockwise or anti-clockwise loop observed in SRR cannot be explained. However, the mechanism proposed here can well reproduce the phenomena observed in many SRR including the clockwise or anti-clockwise loop. In other words, the most important relationship between stock and recruitment is likely to be the interspecific relationship and/or environmental conditions, not the density-dependent effect. If the density-dependent effect observed in SRR is not real, then the MSY theory is not valid, and all the management procedures based on MSY would also not be valid.