生物资源评估 (1)

课程要求
• 了解渔业资源数量变动的原因和规律，特别要理解人为捕捞 对渔业资源和渔获量所产生的影响；
• 掌握鱼类生长和死亡参数的估算方法，理解捕捞努力量的概 念及其标准化的基本方法；
• 掌握渔业资源评估的几个主要的数学模型以及渔业资源和渔 获量的估算与预报的几个主要方法；
课程要求
• 能运用渔业管理理论结合实测的生物学资料、环境资料和所 收集的渔业统计资料所得到的评估结果判断渔业资源利用状 况，
Cadima , E. L. 2003. Fish Stock Assessment Manual. FAO FISHERIES TECHNICAL PAPER 393. /DOCREP/006/X8498E/X8498E00.HTM
考核形式： 考勤：10% 作业： 10% 期中考试：10% 主题演讲：20% 期末考试：50%
mainline
• Demersal Longline: • Pelagic Longline:
- set horizontally on the ocean floor - set near the surface of the water - usually used to catch large tuna and billfish species
=> lures are recovered over the end rollers, the squid fall off into the boat
Dredges
• used to collect shellfish such as scallops from the sea floor • constructed of a heavy steel frame covered with steel mesh, open on the front side which is towed and used to dig scallops out of the sand and mud • the dredge is towed along the bottom until it is full, lifted onto the boat and the contents tipped out
Squid Jigs
• carried out using either mechanically powered or hand operated jigs • overhead lights illuminate the water and attract the squid which gather in the shaded area under the boat • Squid are caught using barbless lures on fishing lines which are jigged up and down in the water
- top of the net is floated at the ocean’s surface, the bottom is held under the water by lead weights
- wire that is threaded through the bottom of the net can be tightened to close the bottom of the net trapping the fish inside
水产资源学，费鸿年、张诗全著，中国科技出版社，1990. 渔业生物数学—资源评估与管理, 叶昌臣，黄斌等，农业出版社，1990. 水产资源学， 能势幸雄、石井丈夫、清水诚著，东京大学出版社，
1992.
水产资源管理概论，松宫义晴著，日本水产资源保护协会，1996.
Gulland, J.A. 1983. Fish stock assessment: A manual of basic methods. John Wiley& Sons, New York.
Seines
• usually long flat nets like a fence that are used to encircle a school of fish, with the boat driving around the fish in a circle
• Purse Seine:
生物资源评估
生物资源评估 (fish stock assessment)
• 研究海洋生物，主要是经济种类即渔业 生物种群动态、数量变动的一门学科。
海洋捕捞渔业产量
捕捞渔业产量呈现下降趋势
FAO 报告 “The State of World Fisheries and Aquaculture”, 2014
渔具技术的演变
• 1870
• Small sailing vessels (smacks) were fishing with beam trawls (<20m).
Seal Excluder Device
• very similar to Turtle Excluder Devices (TEDs) but they are designed for use by seals instead of turtles • They are used in the southern demersal trawl fisheries where seals are more likely to be caught
Bycatch Reduction Devices
• used in trawl fisheries to allow fish that are not targeted by the fishers to escape from the net before it is hauled back into the boat • reduces the amount of bycatch that dies as a result of trawling
• Danish Seine: - more simply constructed with no otterboards and very long warps
Gillnet
• long rectangular panels of netting with diamond-shaped mesh that are held vertically in
to catch fish or prawns that live on the bottom of the ocean nets may incorporate acoustic technology to tell the skipper the position of the net in the water column
Turtle Excluder Device
• used in northern prawn trawl fisheries as an escape hatch for turtles • consist of a grid across the cod-end of the net which forces turtles and other large objects out of the net without the prawn catch escaping
and a narrow closed end called a cod-end • used in water of various depths down to around 3000m; nБайду номын сангаасts differ by their mesh size
• Demersal Trawl: • Midwater trawl:
Traps
• traps are baited so that fish are enticed to swim into them • set up with mazes or funnel-shaped entrances so that fish cannot escape once inside the trap
the water column • anchored either so that the net touches the bottom or so it is suspended above the
ocean floor • fish swim into the net and are entangled by the gills, fins and spines
Droplines
• similar to longlines but are set vertically either down underwater cliffs or just in the water column • a weight at the bottom, a series of hooks attached to snoods, and a float at the top of the line • not usually as long as longlines and don’t have as many hooks
渔业资源的开发利用
• Fishing Methods： • 拖网 • 围网 • 定置网 • 刺网 • 笼壶等
Trawls
• towing one or more trawl nets behind a boat or in between two boats • either through the water column or along the ocean’s floor • usually shaped like a cone or funnel with a wide opening to catch fish or crustaceans