Researches on fauna and stock level of the coastal fishes around Oshika peninsula

Representative Organization: Tohoku University

2014/04/01 - 2015/03/31
once in one or two months

Onagawa Bay (including sea area around Kinkazan Is. and Shizugawa Bay)

Field survey

1. Demersal fishes and benthic animals eel are caught by gill net, pod net, and cage in the Onagawa Bay. Age determination is conducted for the main fisheries resources, for Age-length key.2. Landings at Onagawa fisheries market are investigated. Age and year class compositions are estimated by the age-length key.3. Fish compositions are analyzed to evaluate the effect of the Great East Japan Earthquake on fish fauna, and long-term fluctuation in the composition, through investigation on the logbook of set net fisheries around Kinkazan Is. and Shizugawa Bay.

Demersal fish and megalobenthos faunas were monitored in Onagawa Bay, Miyagi Pref., to assess the direct and indirect effects of this major event. In 2012, 29 species of demersal fish (n=651) were collected using gillnets. Brown hakeling and greenling were dominant, comprising 64% of all individuals. By cluster analysis of species compositions including data in 1981-1995, and 2000-2001, 2012 was found to be in a distinct cluster from the years before the tsunami. Fish fauna in 2012 was characterized as 1. CPUE was significantly higher, 2. Many large sized brown hakeling and greenling were abundant, 3. New recruitments of kurosoi rockfish, surf perch and conger eel were abundant, while marble sole and rockfish were few, 4. Immigrants were in markedly high numbers in the summer. These characteristics suggest no serious long-term effect of the huge disturbance on the fish fauna. In the megalobenthos, 27 species (n=1222) were collected. Densities were estimated to be lower than that before the tsunami. In addition, they were almost small sized animals. The benthos received a more direct impact than demersal fishes, but the fauna is recovering gradually.

FY2014 Researches on fauna and stock level of the coastal fishes around Oshika peninsula