Larval Konosirus punctatus(Clupeidae) in a brackish river mouth on the Pacific coast of central Japan

Abstract

Eggs of Konosirus punctatus in early developmental stages were collected from the eastern part of the mouth of Sagami Bay on the Pacific coast of central Japan. Advanced‐stage eggs and early larvae with notochord length (LN) of <7·5 mm were collected from the inner bay near the mouth of the Sagami River. Feeding larvae of >8·4 mm LN were distributed in the mouth of the river, and juveniles of 24–90 mm standard length (LS) were collected from the lower reaches of the river between the river mouth and c. 3 km upstream of the river mouth. Hatch dates of larvae and juveniles collected in 2001 (n = 158) and in 2002 (n = 109) extended from late March to late July. The relationship between the otolith radius (RO) and LN or LS changed during the metamorphosis stage as characterized by 320 μm RO and 22 mm LS. Otolith growth rate, as an index of somatic growth rates in larval and early juvenile stages, was higher in cohorts that hatched later in the spawning season, i.e. from March to July. Konosirus punctatus that were spawned in the bay mouth area survived with different growth histories in the bay and lower reaches of the river, and recruited to the young‐of‐year population in the Pacific coastal waters of central Japan.