Sustainability assessment of traditional fisheries in Cau Hai lagoon (South China Sea)

• Published in: Marine environmental research Vol. 70; no. 3; pp. 253 - 263
• Main Authors: Marconi, Michele, Sarti, Massimo, Marincioni, Fausto
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01-09-2010; Elsevier
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Applied ecology; Biological and medical sciences; Biopolymeric carbon; Brackish; Carbon; Cau Hai lagoon; China; Coastal waters; Degradation; Density; Environment; Environmental impact; Environmental Monitoring; Eutrophication; Exploitation and management of natural biological resources (hunting, fishing and exploited populations survey, etc.); Fisheries; Fisheries - instrumentation; Fisheries - methods; Fisheries - standards; Fisheries - statistics & numerical data; Fundamental and applied biological sciences. Psychology; Geologic Sediments - chemistry; Lagoons; Marine; Mathematical analysis; Models, Theoretical; Oceans and Seas; Sea water ecosystems; Seasons; Seawater - chemistry; Stake trap; Sustainability; Synecology; Thresholds; Time Factors; Vietnam; Water quality; South China Sea; Asia; Vietnam; China; ISEW, South China Sea; ISEW, Southeast Asia; Stake trap; Vietnam; Biopolymeric carbon; Cau Hai lagoon; Fisheries; Coastal waters; Environmental impact; Trap; Carbon; Coastal zone; Marine environment; Fishery; Environment impact; Coastal water
• ISSN: 0141-1136; 1879-0291
• DOI: 10.1016/j.marenvres.2010.04.009

Overfishing and progressive environmental degradation of the Vietnamese Cau Hai coastal lagoon appear to be threatening the ecological integrity and water quality of the largest estuarine complex of Southeast Asia. This study assessed the relationships between the density of traditional fisheries and organic matter sedimentary contents in Cau Hai lagoon. Data revealed that the density of stake traps (the most common fishing gear used in this lagoon), decreasing hydrodynamic energy in shallow water, causes the accumulation of a large fraction of organic matter refractory to degradation. The relationship between biopolymeric carbon (a proxy of availability of organic matter) and stake traps density fits a S-shape curve. The logistic equation calculated a stake traps density of 90 m of net per hectare, as the threshold over which maximum accumulation of organic matter occurs in Cau Hai. With such level of stake trap density, and assuming a theoretical stationary status of the lagoon, the time necessary for the system to reach hypoxic conditions has been calculated to be circa three weeks. We recommend that this density threshold should not be exceeded in the Cau Hai lagoon and that further analyses of organic loads in the sediment should be conducted to monitor the trophic conditions of this highly eutrophicated lagoon.