Open Journal of Marine Science, 2015, 5, 210-225 Published Online April 2015 in SciRes. http://www.scirp.org/journal/ojms http://dx.doi.org/10.4236/ojms.2015.52017 Factors Affecting Japanese Pond Smelt (Hypomesus nipponensis) Stock Trajectory in Lake Kasumigaura and Kitaura Ashneel Ajay Singh1, Noriyuki Sunoh2, Shintaro Niwa2, Fumitaka Tokoro2, Daisuke Sakamoto1, Naoki Suzuki1, Kazumi Sakuramoto1* 1Department of Ocean Science and Technology, Tokyo University of Marine Science and Technology, Tokyo, Japan 2Freshwater Branch Office, Ibaraki Fisheries Research Institute, Ibaraki, Japan Email: *
[email protected] Received 5 February 2015; accepted 26 March 2015; published 30 March 2015 Copyright © 2015 by authors and Scientific Research Publishing Inc. This work is licensed under the Creative Commons Attribution International License (CC BY). http://creativecommons.org/licenses/by/4.0/ Abstract The Japanese pond smelt (Hypomesus nipponensis) stock has been observed to fluctuate quite ri- gorously over the years with sustained periods of low catch in Lake Kasumigaura and Kitaura of the Ibaraki prefecture, Japan which would adversely affect the socioeconomic livelihood of the lo- cal fishermen and fisheries industry. This study was aimed at determining the factors affecting the stock fluctuation of the pond smelt through the different years in the two lakes. Through explora- tory analysis it was found that the pond smelt had significant relationship with total phosphorus (TP) level in both lakes. The global mean land and ocean temperature index (LOTI) was also found to be indirectly related to the pond smelt stock in lake Kasumigaura and Kitaura at the latitude band of 24˚N to 90˚N (l).