Factors of catch increment of larval and juvenile sand lance [Ammodytes personatus] from 1996 to 1997 in the southern region of Iwate prefecture [Japan]
1999
Nozawa, K. (Iwate-ken. Government Office, Morioka (Japan)) | Kitagawa, D.
Annual changes in catch, distribution and the vertebral number of larval and juvenile sand lance, Ammodytes personatus, in the coastal waters of Iwate Prefecture were examined1. in 1996 and 1997, the catch of sand lance was markedly higher than between 1981-1995. The mean density of larval sand lance collected around Hirota Bay from 1983 to 1995 was in the range of 0.67-15.5 individuals/100 cubic meter and in 1996 and 1997 increased to the range of 45.8-269.3 individuals/100 cubic meter. Many larvae around 5mm in body length, which is the size just after hatching out, were collected by towing a larval net in l986, 1992, 1996 and 1997. It is suggested that these were spawned in the study area regardless of the size of catch. It is known that sand lance with 64 vertebrae are distributed mainly in the coastal waters of Iwate Prefecture, and ones with 62 vertebrae in Sendai Bay. From examination of the vertebral number in 1995-1997 year classes it appears that the proportion of the 62 vertebrae group gradually increased in southern Iwate district from 1995 to 1997. This suggests that the distribution of the 62 vertebrae group has expanded to the northern area
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