INTRODUCTION

In 1997, the First International Symposium on Enhancement and Sea Ranching was held in Bergen, Norway, sponsored by the Norwegian Sea Ranching Programme (PUSH). It reflected the current extensive global activities in this field, stimulated collectively by the continuing concern over the decline of exploited stocks and the considerable advances made in rearing technology over the last two or three decades. At the symposium, Dr D.M. Bartley (1999) from FAO remarked that “a growing human population and its demand for fishery products are placing numerous pressures on the aquaculture environment. As a result, 12 ranching is currently receiving attention as a means to restore or increase production from marine and coastal fisheries”. In fact, his speech reflected the entire trend of world fisheries.

It is in the developing countries that the decline of exploited stocks combined with an increasing demand for seafood are particularly acute, especially in China which has the largest population in the world. As early as the 1970s, Chinese fishery officials and scientists working in this field noted that it was essential to develop sea farming and sea ranching to increase production of marine aquatic products (e.g. Tseng 1978, 1979, 1985a, 1985b, 1988, 1989 and Tseng et al., 1981). They also agreed that these activities greatly contributed to the protection of marine resources and to the prevention of overfishing.

More than two decades later, China has become the largest producer of fishery products in the world (Tables 1 and 2). According to FAO statistics, between 1990 and 1995 world aquaculture production increased by 8.91 million metric tons, of which China contributed 83.6 percent. This aquaculture development has inverted the ratio of capture fisheries production to aquaculture production. In 1978, this ratio was 74:26, to become successively 45.6:54.4 in 1996 and 44:56 in 1999. Currently, China contributes over 70 percent of the world aquaculture production. Even if there is still a long way to reach perfection, it has been shown that sea farming and sea ranching are effective and practicable ways to produce more marine aquatic products, in view to meet the increasing demand for proteins and food from the sea.

Although achieved results are encouraging, many problems are still haunting the minds of both scientists and laymen, such as “genetic pollution” and breakdown of natural ecosystems. But, at the symposium mentioned above, Dr A. Laurec (1999) rightly insisted on “ ... three elements for the scientific communities:

- It would be unwise to block any enhancement attempt because of potential genetic problems.

- Even in those parts of the world where people are not obsessed by ‘genetic pollution’, scientists should address this.

- Even if some problems seem very complicated, the worst attitude would be to ignore them”.

Table 1. Fisheries production in China, 1978 -1999
(in ten thousand metric tons)[1]

Year	Marine capture fisheries	Freshwater capture fisheries	Sea farming/ranching	Freshwater culture	TOTAL
1978	314.52	29.64	44.95	76.23	465.34
1988	463.33	65.44	142.45	389.75	1060.97
1989	503.64	73.44	157.56	417.03	1151.67
1990	550.89	77.85	162.41	445.91	1237.06
1991	609.64	91.26	190.46	462.59	1353.95
1992	691.23	90.08	242.46	533.79	1557.56
1993	767.34	101.88	308.70	648.26	1826.18
1994	895.89	115.26	345.60	789.66	2146.41
1995	1026.84	137.29	412.29	940.76	2517.18
1996	1122.25	159.48	437.65	1093.76	2813.14
1996[2]	1248.98	176.14	763.90	1098.95	3287.97
1997	1385.40	198.70	791.00	1236.70	3611.80
1998	1497.00	228.00	860.00	1321.90	3906.90
1999	1497.60	228.50	974.30	1422.00	4122.40

NOTE: from second set of data for year 1996, production figures according to FAO standards for fisheries statistics

Table 2. Aquaculture production and areas in China, 1978 -1999
(in thousand metric tons and in thousand hectares)

Aquaculture production, 1978-1999

MCP or MCA marine aquaculture
ICP or ICA inland freshwater aquaculture
TP or TA total

MCP or MCA marine aquaculture
ICP or ICA inland freshwater aquaculture
TP or TA total