Digital library

Species of the genus Ulva are used for human consumption due to their nutritional qualities and we assess a new filamentous species, Ulva tepida. A critical step is to quantify the yield and quality of biomass over multiple harvests to ensure consistency throughout the production cycle. To do this, ropes were seeded with U. tepida and harvested fortnightly over 6 weeks of outdoor cultivation with biomass yield and quality quantified for each harvest. This cycle was repeated a further two times. The yield of biomass was not significantly different between harvests (13.6–23.0 g dry weight (dw) m-1 rope), however, the final harvest was highly variable. Consequently, we recommend a production cycle of two harvests. The quality of biomass, as determined by the key biochemical parameters for these two sequential harvests, was consistent. Carbohydrates were the major component (45 % dw) and were primarily dietary fibre (27 % dw) consisting of insoluble (18 % dw) and soluble (9 % dw, equates to ulvan) fibre, with consistent values between harvests. Protein, as the sum of amino acids (17 % dw), was also consistent between harvests. Similarly, the content of ash (31 % dw) and lipids (3 % dw), as well as the composition of minerals and fatty acids was consistent. These results quantify, for the first time, no negative effects of multiple harvests on the yield and quality of biomass and support this technique to optimise productivity and quality.

A groundfish net was modified to limit its bottom contact and to improve escapement of bottom-tending fish species. A model was first evaluated in the flume tank facility of Memorial University, followed by field trials. Two trawl configurations were tested against a Control, during fishing experiments in 2007 and 2008. In the first configuration, the goal was to fish the net approximately 1.5' off the seabed, to retain cod and haddock while reducing catches of flounders and other demersal species. In the second rig, the Experimental trawl was fished up to 3' off the seabed, to retain haddock while reducing catches of cod, flounders and other demersal species.

Flume tank tests indicated that a stable condition and proper fishing heights were achieved with a combination of floats on the headrope, footrope and ground gear, combined with weights attached to the wing ends. Field trials followed the recommendations developed in the laboratory, and video observation revealed a stable fishing condition, with little contact with the seabed. Catch information was hampered by low fish availability, but indicated that the correct escapement pattern was occurring, with the exception of higher-than-desired escapement of haddock during the second experiment. 

The People’s Republic of China has a long history of mariculture production. The mariculture industry in China has achieved breakthroughs in the hatchery, nursery and culture techniques of shrimp, molluscs and fish of high commercial value since the 1950s.

The first major development was seaweed culture during the 1950s, made possible by breakthroughs in breeding technology. By the end of the 1970s, annual seaweed production had reached 250 000 tonnes in dry weight (approximately 1.5 million tonnes of fresh seaweed). Shrimp culture developed during the 1980s because of advances in hatchery technology and economic reform policies. Annual shrimp production reached 210 000 tonnes in 1992. Disease outbreaks since 1993, however, have reduced shrimp production by about two-thirds. Mariculture production increased steadily between 1954 and 1985, but has been growing exponentially since 1986, mostly driven by mollusc culture. Mollusc culture in China began to expand beyond the four traditional species (oyster, cockle, razor clam and ruditapes clam) in the 1970s. Mussel culture was the first new industry to emerge, followed by scallop aquaculture in the 1980s. Abalone culture has become a major industry in the 1990s. Traditional oyster and clam culture has also advanced and expanded in recent years. Now more than 30 species of marine molluscs are cultured commercially in China. Because of the rapid development in recent years, mollusc culture has become the largest sector of the Chinese mariculture industry, accounting for 81 percent of the total production by weight.

Therefore, the industrialization level and culture techniques for the major species in China have reached an advanced international level, with some leading the world aquaculture sector. China is also the largest country in mariculture.

Marine aquaculture has grown rapidly over the last decade. Marine cultivable areas in China, which include shallow seas, mudflats and bays, are estimated to occupy more than 1.33 million ha, as most marine plants and animals can be cultivated within the 10 m isobath using current culture technologies. In 2002 the area under cultivation and the output reached 1 352 000 ha and 12.1 million tonnes, respectively.

The principal species cultured in northern China are listed in Table 1. 

In addition to striving to meet the United Nations Millennium Development Goals, the global community is also grappling with other pressing and complex challenges such as the widespread economic crisis and the effects of climate change. It is in this context that this edition of The State of World Fisheries and Aquaculture highlights the vital role of fisheries and aquaculture in both food and nutrition security as well as economic expansion.

The sector remains a major supplier of high-quality animal protein and supports the livelihoods and well-being of more than ten percent of the world’s population. International trade in fish has reached new peaks as overall production has continued to rise. Yet, as the document underlines, an array of problems – ranging from the need for more effective governance to that of ensuring environmental sustainability – threatens to undermine the sector’s valuable contribution to alleviating hunger and reducing poverty.

Using the latest available statistics on fisheries and aquaculture, this edition presents a global analysis of the sector’s status and trends. It also examines broader related issues such as gender, emergency preparedness and the ecosystem approach to fisheries and aquaculture. Selected highlights, from ecolabelling and certification to the effects of fisheries management policies on fishing safety, provide insights on specific topics. Finally, the document looks at the opportunities and difficulties for capture fisheries in the coming decades.