Impacts of the Covid-19 pandemic on Vietnam's marine fisheries

Phuong, To Van and Nguyen, Khanh Quoc and Nguyen, Luong Trong and Vu, Nghiep Ke (2023) Impacts of the Covid-19 pandemic on Vietnam's marine fisheries. Asian Fisheries Science Journal (Malaysia), 36. pp. 68-78. ISSN 2073-3720

Blood cockles, Tegillarca granosa (Linnaeus, 1758), were induced to spawn by temperature stimulation. Larval to spat rearing was accomplished in the hatchery facility of the Institute of Aquaculture of the University of the Philippines Visayas. The survival rate from day 1 larval stage to day 120 spat stage was 2.48 % (15,200) from the initial 614,100 eggs reared. The fertilised eggs (average size: 50.23 ± 5.18 µm in diameter) passed through the morula stage 5 h postfertilisation and reached the trochophore stage after 8 h. Day 1 D-shaped larvae (average size: 84.60 ± 3.90 µm length (l) and 66.36 ± 1.92 µm height (h)) transformed into umboned larvae by day 7. The majority of the larvae reached the advanced umbo stage by day 12 (average size: 204.52 ± 21.06 µm l and 178.24 ± 17.04 µm h). By day 20, loss of velum and foot development in larvae were observed, marking the beginning of the pediveliger stage. The growth of post-set larvae starting from the initial settling stage at day 30 (average size: 360.50 ± 52.10 µm l and 309.56 ± 34.56 µm h) to day 120 (average shell length: 3.870 ± 0.400 mm) was periodically monitored. Cockle spats had squarish shells with central elevation and visible radial ribs resembling the morphological characteristics of adult T. granosa. Only Isochrysis galbana Parke, 1949, was given as food for the cockles throughout the rearing activity. Further refining of larval and post-set rearing methodology is necessary for future mass production of cockle seeds in the Philippines.

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Abstract

Blood cockles, Tegillarca granosa (Linnaeus, 1758), were induced to spawn by temperature stimulation. Larval to spat rearing was accomplished in the hatchery facility of the Institute of Aquaculture of the University of the Philippines Visayas. The survival rate from day 1 larval stage to day 120 spat stage was 2.48 % (15,200) from the initial 614,100 eggs reared. The fertilised eggs (average size: 50.23 ± 5.18 µm in diameter) passed through the morula stage 5 h postfertilisation and reached the trochophore stage after 8 h. Day 1 D-shaped larvae (average size: 84.60 ± 3.90 µm length (l) and 66.36 ± 1.92 µm height (h)) transformed into umboned larvae by day 7. The majority of the larvae reached the advanced umbo stage by day 12 (average size: 204.52 ± 21.06 µm l and 178.24 ± 17.04 µm h). By day 20, loss of velum and foot development in larvae were observed, marking the beginning of the pediveliger stage. The growth of post-set larvae starting from the initial settling stage at day 30 (average size: 360.50 ± 52.10 µm l and 309.56 ± 34.56 µm h) to day 120 (average shell length: 3.870 ± 0.400 mm) was periodically monitored. Cockle spats had squarish shells with central elevation and visible radial ribs resembling the morphological characteristics of adult T. granosa. Only Isochrysis galbana Parke, 1949, was given as food for the cockles throughout the rearing activity. Further refining of larval and post-set rearing methodology is necessary for future mass production of cockle seeds in the Philippines.

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Item Type:	Article
AGROVOC Term:	marine fisheries
AGROVOC Term:	fishery products
AGROVOC Term:	pandemics
AGROVOC Term:	economic impact
AGROVOC Term:	surveys
AGROVOC Term:	questionnaires
AGROVOC Term:	fishermen > fishermen Prefer using fishersfishers
AGROVOC Term:	economic losses
AGROVOC Term:	public health
Geographical Term:	Vietnam
Depositing User:	Nor Hasnita Abdul Samat
Date Deposited:	23 Jul 2024 01:38
Last Modified:	23 Jul 2024 01:38
URI:	http://webagris.upm.edu.my/id/eprint/916

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