TY - JOUR
T1 - Dietary Effect of Kelp (Saccharina japonica) on Gonad Quantity and Quality in Sea Urchins (Mesocentrotus nudus) Collected from a Barren before the Fishing Season
AU - Takagi, Satomi
AU - Murata, Yuko
AU - Inomata, Eri
AU - Endo, Hikaru
AU - Aoki, Masakazu N.
AU - Agatsuma, Yukio
N1 - Funding Information:
We sincerely thank Associate Professor T. Yamaguchi, assistant professor T. Nakano, and Dr. Y. Shiba of Tohoku University for their technical support for the measurement of sea urchin gonad hardness. We are grateful to the operative chief N. Sasaki and head of youth division Y. Sugawara, and other staff of the Shizugawa Branch of the Miyagi Fisheries Cooperative Association for their full cooperation with managing the sea urchin cage culture and Dr. Y. Sato of Riken Food Co., Ltd. for providing Saccharina japonica. We also thank M. Oshima and S. Kodama of Diving Stage Ariel for collecting sea urchins for culture and for the maintenance of the culture facility. This study was financially supported by the project ‘‘Tohoku Ecosystem-Associated Marine Science (TEAMS),’’ Ministry of Education, Culture, Sports, Science and Technology, Japan.
Publisher Copyright:
© 2018 National Shellfisheries Association. All rights reserved.
PY - 2018/8
Y1 - 2018/8
N2 - The sea urchin Mesocentrotus nudus is commercially harvested between June and August in northeastern Japan. A previous study showed that feeding on Saccharina japonica between April and June resulted in gonad quantity and quality improvement in this species from a barren. No information is available on the optimal culture period for harvest before the fishing season. The purpose of this study was to determine whether gonad size and quality (color, texture, and taste) can be improved before the fishing season and to verify the possibility of an early harvest. The sea urchins M. nudus were collected from a barren and placed under two types of culture conditions: suspended cages in a bay and a laboratory circulation system. They were fed S. japonica between December and May or March. Gonad indices, hardness, and color [L∗, a∗, and b∗, and ΔEab∗ (a unit of acceptable commercial color difference from a fishing ground for each treatment)], and free amino acid (FAA) contents of the urchin gonads at the start of rearing experiments and at the end of cage (C) and laboratory feeding (LF) cultures were measured. These variables were also compared between LF and laboratory-starved urchins to confirm the dietary effect of this kelp. Gonad indices in treatments C and LF were significantly higher than those at the start of the experiment and those in laboratory starvation (P < 0.01), although there was no significant difference between C and LF. Gonads in treatment C were significantly softer than that at the start of the experiment (P < 0.0001). ΔEab∗ of gonads in treatment C was the lowest, indicating that the gonad color was close to the preferred color. There was no significant difference in the total FAA content between C and LF treatments, whereas, of the umami FAA, glutamic acid content was significantly higher in gonads from C than LF. Of the bittertasting FAA, tyrosine and valine contents were significantly higher in LF gonads than in C gonads. These results suggested that gonad size, hardness, and color of M. nudus were improved before the fishing season by initiating culture in December with S. japonica feeding.
AB - The sea urchin Mesocentrotus nudus is commercially harvested between June and August in northeastern Japan. A previous study showed that feeding on Saccharina japonica between April and June resulted in gonad quantity and quality improvement in this species from a barren. No information is available on the optimal culture period for harvest before the fishing season. The purpose of this study was to determine whether gonad size and quality (color, texture, and taste) can be improved before the fishing season and to verify the possibility of an early harvest. The sea urchins M. nudus were collected from a barren and placed under two types of culture conditions: suspended cages in a bay and a laboratory circulation system. They were fed S. japonica between December and May or March. Gonad indices, hardness, and color [L∗, a∗, and b∗, and ΔEab∗ (a unit of acceptable commercial color difference from a fishing ground for each treatment)], and free amino acid (FAA) contents of the urchin gonads at the start of rearing experiments and at the end of cage (C) and laboratory feeding (LF) cultures were measured. These variables were also compared between LF and laboratory-starved urchins to confirm the dietary effect of this kelp. Gonad indices in treatments C and LF were significantly higher than those at the start of the experiment and those in laboratory starvation (P < 0.01), although there was no significant difference between C and LF. Gonads in treatment C were significantly softer than that at the start of the experiment (P < 0.0001). ΔEab∗ of gonads in treatment C was the lowest, indicating that the gonad color was close to the preferred color. There was no significant difference in the total FAA content between C and LF treatments, whereas, of the umami FAA, glutamic acid content was significantly higher in gonads from C than LF. Of the bittertasting FAA, tyrosine and valine contents were significantly higher in LF gonads than in C gonads. These results suggested that gonad size, hardness, and color of M. nudus were improved before the fishing season by initiating culture in December with S. japonica feeding.
KW - gonad quality
KW - kelp
KW - Mesocentrotus nudus
KW - Saccharina japonica
KW - sea urchin
UR - http://www.scopus.com/inward/record.url?scp=85052712999&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85052712999&partnerID=8YFLogxK
U2 - 10.2983/035.037.0318
DO - 10.2983/035.037.0318
M3 - Article
AN - SCOPUS:85052712999
SN - 0730-8000
VL - 37
SP - 659
EP - 669
JO - Journal of Shellfish Research
JF - Journal of Shellfish Research
IS - 3
ER -