No.89(March,2016)
No.89(March,2016)
A-531 Yohei SHIMIZU, Toshiaki KARINO, Moriyoshi NARITA, Shoichi ITAKURA, Koichiro ENOMOTO, Masashi TODA, Takuma KAWASAKI, Shin-ichi TAKABATAKE, Toshiharu IWAI, and Masakane YAMASHITA
Practical improvement of the immunostaining method used for investigating the distribution of Japanese scallop (Mizuhopecten yessoensis) larvae in the field
For the efficient collection of natural spats of Japanese scallop (Mizuhopecten yessoensis), the distribution and development of larvae in the field should be periodically monitored at various areas in the sea. To simplify this task, an immunostaining method using polyclonal antibodies that specifically react with Japanese scallop larvae is being utilized, however, some processes of the immunostaining require improvement. In the present study, we examined the optimal conditions of fixation in the immunostaining technique to obtain stable immunostaining results. We found that fixation of samples with 0.9% formaldehyde or 0.5% glutaraldehyde in sea water overnight leads to constant and reliable results. The optimization of the antigen-antibody reaction and chromogenic reaction also shortens the total time required for immunostaining.
A-532 Yasuyuki MIYAKOSHI, Makoto FUJIWARA, Daisei ANDO and Mitsuhiro NAGATA
Return of chum salmon released from a river and a net-pen in eastern Hokkaido
Marked juvenile chum salmon, Oncorhynchus keta, were released from the Abashiri River and a net-pen installed in the fishing port near the river mouth from 2003 to 2005 to compare the numbers of marked fish recovered in coastal commercial fishery and in river catch for broodstock. The number of marked fish recovered in the coastal fishery was higher for net-pen release than for river release for fish stocked in 2003, but lower for fish stocked in 2004 and 2005. The numbers of recovered fish in the river was observed to be lower for net-pen releases than for river releases in all cases when compared to the number of recoveries in the coastal fishery. Although release from a net-pen can be an effective stocking method for chum salmon, it should not be considered for broodstock collection. In addition, return timing and maturity level also differed between fish released from the river and the net-pen..
A-533 Kiyoshi KASUGAI and Yoshitaka SASAKI
Relationship between release sites and return of adult chum salmon to the rivers in the Nemuro Region, eastern Hokkaido
The relationships between the release sites of chum salmon Oncorhynchus keta fry and the return of adult salmon to the river was examined by comparing the number of released chum salmon fry from 1984 to 2012 (brood years) and that of returned adult salmon four years after their release in the 11 rivers of the Nemuro Region, eastern Hokkaido, northern Japan, where fry were stocked and adults were captured. A significant positive correlation was observed between mean river return rates and downstream distances in each river-shorter the downstream distance, the lower the river return rate. Moreover, a significant negative correlation between the coefficient of variation for river return rate and downstream distance indicated that these rates might fluctuate considerably in rivers with short downstream distances.
A-534 Hiroki ASAMI
A euphausiid, Thysanoessa longipes, infected by an anisakid larva in the northern Japan Sea off Hokkaido (Short paper)
A euphausiid, Thysanoessa longipes, infected by an anisakid larva was found in the northern Japan Sea off Hokkaido in April 2014. The anisakid larva was identified as Anisakis larva Type I (Anisakis simplex s.s.) from its morphological characters. This paper describes the new locality of Thysanoessa longipes infected by a Type I anisakid larva.