- Habitat mapping of the spawning grounds for some economic fish species in the family Sciaenidae (croaker fishes) distribute in the coastal waters of Quang Ninh – Hai Phong by the passive acoustic techniques.
- Proposition of the seasonal/temporal close areas to protect the wild stock and sustainably develop of the natural fishery resources in the study area.

- Theretical results
+ Environmental condition at the spawning grounds: The estuaries of Tien Yen, Bach Dang and Van Uc rivers have favorable condition to support the spawning grounds of the croaker fishes (family Sciaenidae).
+ The composition of the fish egg and fish larvae: there have been 32 families of fish egg and fish larvae recorded at the study area. Among of them, the family Sciaenidae had 7 genera with the egg density and fish larvae were 136.67 units per 1.000m3.
+ The species composition of the family Sciaenidae:  there have been 15 species of croaker fishes found in the study area belonged to 9 genera.
+ Biological characteristics, reproduction biology and aggregation behavior of the croaker fishes: Most species found at the study area reached the maximum size and body weight in February and August annually. They are also mature and do the mass spawning events in these months.
+ Sound features of the croaker fishes at the captive condition: 3 species were selected to keep in the aquarium for sound recording purposes to build a sound database for each species. They are Collichthys lucidus, Nibea soldado and Pennahia anea.
+ Habitat mapping of the spawning grounds: There were 8 spawning grounds have been marked at the Tien Yen estuary: 04 locations, Bach Dang: 02 locations and Van Uc estuary: 02 locations.
+ Proposition of the seasonal/temporal close areas to protect the wild stock and sustainably develop of the natural fishery resources: It was emerging needed to include the 8 spawning grounds as the seasonal/temporal close fishing pracices from February to April and August to October annually. There are several practical solutions such as: zonning plan towards the ecosytem based management, scientific technical approaches, public awareness enhancement and sustainable fishing practices.

- Applied results
The outcomes of this project will provide the scientific baselines for establishment of natural wetland protected areas at the estuaries as well as protection of the fishery refugia sites at the coastal waters.

Considering as the pioneer study in using the passive acoustic to study the croaker fishes in Vietnam and this can be scaled up at the larger scale for other target species.

- Scientific papers in referred journals (list)
+ Publication in the national peered review journal/proceedings

1. Pham Van Chien, Nguyen Van Quan, Nguyen Cong Son, 2019. The species composition of the croaker fishes (family Sciaenidae) at the estuaries of Quang Ninh – Hai Phong. Journal of Marine Science and Technology, 19 (3): 261-268.
2. Nguyen Van Quan, Nguyen Cong Sơn, Dam Thi Len, Pham Van Chien, Nguyen Thi Huong Lien, 2019. The species diversity of fishes in the marine area of Ha Long Bay. Proceedings of the 1st National Conference on Ichthyology in Vietnam. Pp: 182-190.

+ Publication in the international peered review journal (SCI/SCI-E list)

1. Thinh Dinh Do, Chien Pham Van, Dong Dao Minh, Thanh Vu Quyet, Quan Nguyen Van, Chang-Bae Kim, 2020. Sequencing and Analysis of mitochondrial genome of Pennahia anea (Perciformes: Sciaenidae). Mitochondrial DNA Part B: Resources.
2. Nguyen Ngoc Anh, Nguyen Van Quan, 2020. A tentative sediment budget for the Red River subaqueous delta in the Gulf of Tonkin: A synthesis of existing data. Regional Studies in Marine Science, Volume 34, February 2020, 101005.
3. Harutaka Hata, Nguyen Van Quan, Tran Manh Ha, Hiroyuki Motomura, 2020. Thrissina belvedere, a new thryssa from Ha Long Bay, northern Vietnam and redescription of Thrissina chefuensis (Günther 1874) (Clupeiformes: Engraulidae). Ichthyol Res. DOI 10.1007/s10228-020-00743-9.
4. W.C. Huang, V. Q. Nguyen, T.-Y. Liao, 2018. First record of the snowflake-patched moray Gymnothorax niphostigmus Chen, Shao, & Chen, 1996 (Anguilliformes; Muraenidae) in Vietnam and its validity confirmed by DNA barcoding. J Appl Ichthyol. 2018;1–4. DOI: 10.1111/jai.13684.

+ Monograph book

1. Kimura, S., H. Imamura, V. Q. Nguyen and T. D. Pham eds. 2018. Fishes of Ha Long Bay, the natural world heritage site in northern Vietnam. Fisheries Research Laboratory, Mie University, Shima, Japan. ix+314

- Patents (list): None

- Technological products (describe in details: technical characteristics, place):

• Field data collected, analysis data sheets on the current distribution of the spawning grounds, fishing activities and utlization of the croaker fishes at the estuaries of Quảng Ninh – Hai Phong.
• Skematic map of the spawnig grounds for 3 species of the croaker fishes att the esturies of Tien Yen, Bach Dang and Van Uc.
• Biological features, and physical oceanography parameters relating to the formation of the spawning grounds and nursery areas.
• Management solutions for protection of the spawning grounds at the estuaries in the study area.
• Specimens collection of the selected croaker fishes in this study.

- Other products (if applicable): contribute the available data set for 01 PhD student and trained 01 MSc student to be awared the MSc degree from Graduate University of Science and Technology (Vietnam Academy of  Science and Technology)

The outcomes of this study can be transferred to the local authorities such as Department of Environment and Natural Resources, Department of Agricultural and Rural Deelopment of Quang Ninh and Hai Phong. The skematic map of the spawning grounds are meaningful sources for the Ha Long Bay Management Board and the Cat Ba World Biosphere Reserve to boos up the effecive management of the fishery resources at the coastal areas.

Using the passive acoustic techniques to determine the spawning grounds of fishes is the new approach in Vietnam. We need to put more efforts in this research strategy to apply for other marine endangered species like the Chinese Dolphin (Sousa chinenses) or Dugong (Dugong dugon).