The population dynamics of eight commercial species of shrimp (Haliporoides sibogae, Harpiosquilla harpax, Metapenaeus affinis, Metapenaeus brevicornis, Metapenaeus tenuipes, Parapenaeopsis cultrirostris, Parapenaeopsis gracillima and Parapenaeus maxilipedo) distributed in littoral marine zone of the Mekong Delta were investigated. Length-based stock assessment using FiSAT II software package was used to assess the growth and mortality parameters: Asymptotic size (L8), growth coefficient (K), total (Z) and natural (M) mortality, exploitation rate (E), recruitment pattern, current probability of capture and selectivity of fishing gears. Yield-per-recruit analyses were carried out showing different levels of the exploitation. Results showed that the maximum sustainable yield would be reached for an exploitation rate higher than the current one for each population. However, the size of first capture should be increased for every population. The findings indicated that the current exploitations of shrimp populations distributed in littoral marine zone of the Mekong Delta are under exploitation level for maximum sustainable yield; however, all the shrimp populations are subject to growth over-exploitation.

This work examined diet composition of the juvenile orange-spotted grouper, Epinephelus coioides, and its trophic association with other juvenile fish species in tropical estuarine habitats during recruitment. From December 2015 to March 2016, juveniles were collected, their stomachs excised, preserved and analyzed. Small shrimps and amphipods, especially Grandidierella sp. and Elasmopus sp., were the most common food resources sharing among the most species. Epinephelus coioides predominantly ingested small shrimp, Grandidierella sp., Elasmopus sp. and fish larvae and had the greatest trophic overlap with Palatrus scapulopunctatus. Fish size, location and month significantly affected fullness indices and food items diversity in E. coioides. It is clear that the larger the size of E. coioides and its mouth opening, the larger the size of items ingested. This study confirms the ontogenetic dietary shift of juvenile E. coioides during recruitment season by starting as amphipod and small shrimp feeder and shifting to shrimp and fish larvae predator as they grow. This finding is fundamental to understanding how juvenile E. coioides cope with different conditions and its association with other co-existing species during the recruitment period.

Contribution/ OriginalityThis study is one of very few studies, which have investigated the impact of climate change on snakehead seed production. The paper's primary contribution is finding that which and how climate phenomenon has effected on seed production as well as suggesting some adaptive methods for them.

No abstract

This study was conducted from December 2015 to November 2016 at 44 sampling sites in the Hau River Basin at Hau Giang Province. The analysis results recorded 125 fish species belonging to 19 Orders and 46 families. The fish species composition was more diverse in wet season (119 species) than that in dry season (101 species). Of 19 orders, Cypriniformes, Siluriformes, Anabatiformes, Perciformes and Gobiformes had the highest number of species recorded during wet and dry seasons. The fish species composition had higher diversity in the ecological region regulated by east sea tide than the ecological region regulated by west sea tide and the contiguous ecological region. Keyword Rish species composition, Hau Giang, Hau river References [1] Vũ Vi An, Đoàn Văn Tiến, Lâm Phước Khiêm & Nguyễn Nguyễn Du, Đánh giá sản lượng khai thác của ngư dân vùng Đồng bằng sông Cửu Long, Tuyển tập Nghề cá sông Cửu Long, 428-436, 2011.[2] Mai Đình Yên, Nguyễn Văn Trọng, Nguyễn Văn Thiện, Lê Hoàng Yến & Hứa Bạch Loan, Định loại cá nước ngọt Nam bộ, Nxb Khoa học và Kỹ thuật, Hà Nội, 1992.[3] Trương Thủ Khoa & Trần Thị Thu Hương, Định loại cá nước ngọt vùng Đồng bằng sông Cửu Long, Tủ sách Đại học Cần Thơ, Cần Thơ, 1993.[4] Đoàn Văn Tiến & Mai Thị Trúc Chi, Quan Trắc sản lượng cá đánh bắt ở Đồng bằng sông Cửu Long, Hội thảo quốc gia về phát triển thủy sản vùng hạ lưu sông Mekong, Việt nam, Nxb Nông nghiệp, 2005.[5] Trần Đắc Định, Koichi, S., Nguyễn Thanh Phương, Hà Phước Hùng, Trần Xuân Lợi, Mai Văn Hiếu & Kenzo, U., Mô tả định loại cá Đồng bằng sông Cửu Long, Việt Nam, Nxb Đại học Cần Thơ, Cần Thơ, 2013.[6] Viện Quy hoạch thủy lợi miền Nam, Quy hoạch xây dựng thủy lợi tỉnh Hậu Giang đến năm 2020 và tầm nhìn đến năm 2030 (Tập 1 Báo cáo tổng hợp), Thành phố Hồ Chí Minh, 2012.[7] Phạm Nhật, Vũ Văn Dũng, Đỗ Quang Huy, Nguyễn Cử, Lê Nguyên Ngật, Nguyễn Hữu Dực, Nguyễn Thế Nhã, Võ Sĩ Tuấn, Phan Nguyên Hồng, Nguyễn Văn Tiến, Đào Tấn Hổ, Nguyễn Xuân Hòa, Nick Cox & Nguyễn Tiến Hiệp, Sổ tay hướng dẫn điều tra và giám sát đa dạng sinh học, Nxb Giao thông vận tải, Hà Nội, 2003.[8] Pravdin, I. F., Hướng dẫn nghiên cứu cá (Phạm Thị Minh Giang dịch), Nxb Khoa học và Kỹ thuật, Hà Nội, 1973.[9] Nguyễn Văn Hảo & Ngô Sỹ Vân, Cá nước ngọt Việt Nam, Nxb Nông Nghiệp, Hà Nội, 2001.[10] Nguyễn Văn Hảo, Cá nước ngọt Việt Nam, Nxb Nông nghiệp, Hà Nội, 2005.[11] Nguyễn Văn Hảo, Cá nước ngọt Việt Nam, Nxb Nông nghiệp, Hà Nội, 2005.[12] Rainboth, W. J., Fishes of the Cambodian Mekong, FAO, Roma, 1996.[13] Froese, R. & Pauly, D., FishBase, World Wide Web electronic publication, 2017, truy cập ngày 10/06/2017. www.fishbase.org[14] Nguyễn Ngọc Anh, 2016. Hạn - mặn lịch sử 2016 ở Đồng bằng sông Cửu Long: bài học kinh nghiệm và những giải pháp ứng phó, Tạp chí Khoa học và Công nghệ Việt Nam, Hà Nội, 19/01/2018, http://www.khoahocvacongnghevietnam.com.vn/khcn-trung-uong/13123-han-man-lich-su-2016-0-dong-bang-song-cuu-long-bai-hoc-kinh-nghiem-va-giai-phap-ung-pho.