稚魚網で同時に採集される魚卵・雅魚数とプランクトン量との関係について

抄録

Studying on the relation between the quantities of the next three groups-eggs of fishes, larvae of fishes and plankton-collected simultaneously by a horizontal surface haul with the larval net, the following results were obtained. 1. When abundant (more than 1,000 individuals) eggs of fishes are collected, the other two groups were rather scanty : When abundant (more than 1,000 individuals) larvae of fishes are collected, the other two groups were rather scanty : and likewise when abundant (more than 200cc in settling volume) plankton are collected, the other two groups were scanty. It never happened that two or all of these three groups were collected in abundance at the same time. 2. The reverse to above mentioned relation does not hold good, two or three groups may be scanty simultaneously. 3. When the eggs of the fishes (or another group) are collected in abundance fully, in the general case, one special species of the group among it was extremely dominant. Considering the above mentioned facts, it is supposed that the mechanisms of the formation of patches (the dense swarms) are different according to the eggs of the fishes, larvae of the fishes or to the plankton. The patches of these planktonic or semi-planktonic organisms are not due only to the mechanical actions of the external force, but also to the reactions and behaviours of the organisms in various ways according to the species.