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The causative agent responsible for vibriosis in tropical fish aquaculture, Vibrio harveyi, has become a major bacterial pathogen. Studies suggest that this bacterium has developed resistance to antibiotics commonly used in aquaculture. In view of this situation and the requirement for the proposed postantibiotic era, bacteriophage therapy seems to be a promising control strategy for fish vibriosis. In this study, a lytic Vibrio phage VhKM4 belonging to a member of large, marine Myoviridae was successfully isolated. It exhibited bacteriolysis to both V. harveyi VHJR7 and V. parahaemolyticus ATCC 17802. The latent period of the VhKM4 phage was recorded at 60 min. It also recorded average burst size of approximately 52 plaque-forming units per infected cell. A strong bacteriolytic activity at low multiplicity of infection of 0.01 indicates the effectiveness of this large marine myovirid against fish pathogenic strain of V. harveyi VHJR7. Received June 16, 2016; accepted October 7, 2016.

Bivalve aquaculture accounts for 14%-16% of the average per capita animal protein of 1.5 billion people, supporting more than 200,000 livelihoods, mostly in developing countries. Massive mortality outbreaks of various cultured bivalves have been reported worldwide. Repeated episodes of mass mortality not only reduce the production and cause high economic losses but also have a negative impact on natural bivalve populations. The present article reviews the scientific evidence of mass mortality outbreaks of marine bivalve molluscs affected by extrinsic factors. It attempts to summarize the pertinent data published on specific research issues to improve understanding of the diverse factors. This helps to clarify the present state of research and to identify topics for future studies on bivalve mass mortality. It can be seen from the published data that bivalve mass mortality episodes are rarely caused by single factors but are more likely to be triggered by synergistic effects of two or more factors. Understanding these factors could aid in the development of good aquaculture practices and effective fishery management plans for bivalves. KEY WORDS: marine bivalve, mass mortality, extrinsic factors, review, INTRODUCTION Molluscan aquaculture in general and bivalve farming in particular have brought significant social and economic benefits to coastal communities. Bivalve aquaculture accounts for 14%-16% of the average per capita [...]

The mangrove clam, Polymesoda erosa is among the commercially important bivalve species in Marudu Bay, Malaysia. However, a recent study has shown that this species experiences a high level of fishing exploitation. To sustain this species, one potential strategy is to restock hatchery-produced seeds through sea ranching. However, this requires the successful artificial production of seeds, which currently has not been achieved. The present study was conducted to determine the sex ratio and maturity level of different shell length classes of the clam to guide the selection of broodstock for artificial propagation in the future. A total of 240 mangrove clam specimens were randomly collected from the mangrove swamps in Marudu Bay and sorted into four shell length classes: 5.50-6.49 cm, 6.50-7.49 cm, 7.50-8.49 cm and 8.5-9.49 cm. The clams were subjected to gonad histological examination and condition analysis. Results showed that the natural stock of clams exhibited close to a 1:1 male-to-female sex ratio with no hermaphroditism observed. Clams within the 5.50-8.49 cm shell length classes had high gonad index, indicating that most of the clams at this size are fully mature. Statistical analysis revealed a significant difference (p = 0.027) in condition index between two shell length classes: 5.50-6.49 cm and 7.50-8.49 cm. This could be attributed to differences in energy utilization; young clams utilize more energy for growth, whereas adult clams utilize energy for growth, reproduction, and metabolic maintenance. This study suggests that using mangrove clams with shell length between 5.50 cm and 8.49 cm will likely result in high spawning success in an artificial breeding program. [ABSTRACT FROM AUTHOR]

An outbreak of the fish-ectoparasitic marine isopod Caecognathia coralliophila (Monod, 1926)occurred in a fish hatchery in Sabah on Borneo Island, Malaysia. Larval stages of gnathiid isopods are parasitic on fish whereas their adult stages are free-living. The original description of C. coralliophila (Monod, 1926) was based on the morphology of one adult male from Thailand, and no description of the adult female or larva has been published to date. We compared the holotype of C. coralliophila and redescribed adult males and adult females as well as third-stage larvae from the fish hatchery. This paper provides a redescription of C. coralliophila based on all phases of the life history. Caecognathia coralliophila is distinguished from congeners by having reduced setae on the distal margins of the pleopodal endopods in adult males, biarticulate pylopods and the setae on the pleopodal rami being reduced in adult females, and antenna much longer than antennule in third-stage larvae. [ABSTRACT FROM AUTHOR]