岡山県高梁川における産卵期のシラウオ

抄録

Four-armed scoop net fishery for Salangichthys microdon Bleeker is operated in the Takahashi estuary, Okayama Prefecture, yielding 10-17 tons of the fish annually.Although the daily catch per boat averaged 7-8kg during the main fishing season, February to March, the catch fluctuated considerably and irregularly without obvious relationship with the lunar calendar or the tidal conditions.The fish caught in this fishing ground were rather large in size.The condition factor of the fish was found to be high.Females exceed the males in body length, but reversed in body weight.An inverse correlation between the gonad index and the condition factor was not found in individual fish, though a decrease in the condition factor after spawning was obvious for the group as a whole.About 1300 to 2700 eggs were counted in a pair of ovaries. There was no clear correlation between the number of ovarian eggs and the body length or the body weight of the fish.Larvae of a gobiid fish, Chaenogobius sp.as well as mysid shrimps, Neomysis sp.were found in the digestive organs of the fish.