Differences in free amino acid composition between testis and ovary of sea urchin <Emphasis Type="Italic">Anthocidaris crassispina</Emphasis> during gonadal development

ABSTRACT:   For the purpose of clarifying the differences of taste components between the testis and ovary of the sea urchin Anthocidaris crassispina , variations in free amino acid composition in gonadal extract during gonadal development were investigated using chemical and histopathological methods. Sea urchins were collected at Iki Island, Nagasaki, Japan between 30 April and 5 June 2003, and maturation stages and the free amino acid compositions were determined. The sweet amino acids threonine (Thr), glycine (Gly), and alanine (Ala), the umami amino acid glutamic acid (Glu), and the bitter amino acids lysine (Lys) and arginine (Arg) were the main constituents accounting for more than 80% of total free amino acids. In the testis and ovary, Gly levels were the highest among them and increased with gonadal development. The other free amino acids consisted mainly of bitter amino acids and either showed no variation or decreased with gonadal development. These variations in free amino acid composition were observed more clearly in the ovary than the testis. These findings indicate the possibility of differences in the flavor of sea urchin gonad by sex and gonadal development stages.     

Automated acoustic method for counting and sizing farmed fish during transfer using DIDSON

Counting and sizing large farmed fish such as tuna is often performed during their transfer from one net cage to another. Dual-frequency identification sonar (DIDSON) provides an automated fish counting and sizing tool. However, its counter and sizer are not suitable for measuring farmed fish because of net movements due to currents and subsequent frequent image breakups. This paper presents a fully automated acoustic method to count and size farmed fish during fish transfer by using DIDSON imaging. The background is subtracted from the image after being stabilized by an image phase-only correlation method. The segmentation of the fish is obtained by tracing the edges with a contour tracing method. To prevent recounting the same fish, a Kalman filter algorithm was designed and adapted to predict fish movements. Automated counting was performed by analyzing the spatiotemporal trajectory of the track. The separated fish images were searched for and body length was obtained by summing down the centerline segments from the head to the tail of the fish. The proposed system was verified using farmed yellowtail, Seriola quinqueradiata (mean total length 83.1 cm) to obtain a sizing error of mean total length within 2.4 cm.     

Chemical components and body color of horse mackerel caught in different areas

ABSTRACT: The chemical components and body color of horse mackerel caught between July 1997 and May 2000 were studied. The fish were caught with small- to medium-sized purse seine offshore from Nagasaki and from Tsushima, and with bull trawl seine and medium- to large-sized purse seine in the East China Sea. The crude lipid content of the fish caught offshore from Tsushima was higher than that of the others, and there were no significant differences among the other catches. The extractive nitrogen content of the fish caught with bull trawl seine was somewhat lower than that of the others. The body colors of the fish differed from those suggested by their common names: Kuroaji (black) , Kiaji (yellow), and Shiroaji (white). The crude lipid content and body color indicated that there was no difference in quality among the catches, with the exception of the crude lipid content of the Tsushima catch.