How to amend land subsidence treatment policies to solve coastal subsidence problems in Taiwan
Coastal land subsidence is a serious problem in Taiwan. Starting in 1995, the goal of the “Land Subsidence Prevention and Treatment Implementation Program” is to restructure the aquaculture industry to reduce groundwater consumption and reduce coastal land subsidence problems. However, this goal has not been met. This study aims to determine the reasons for its failure through a literature review and an analysis of questionnaires of stakeholders taken over a 5-year period, and design a new program to resolve these problems. The study was conducted in 2005–2009. According to the literature, over-pumping of groundwater around densely concentrated coastal fish ponds is the primary cause of coastal land subsidence. However, the key measure of the program was to establish aquaculture districts primarily in subsiding coastal areas, which failed to reduce land subsidence. In addition, the program did not consider reductions in agricultural and industrial groundwater use. Results of the questionnaire survey were in accord with the literature review results. This paper proposes to establish a “Fish Farming Abandonment Program” offering compensation payments and job training to fish farmers who leave the aquaculture business, thus reducing the amount of coastal land devoted to fish farming, decreasing groundwater consumption, and halting further coastal subsidence. In addition, the proposal also suggests adjustments to the structure of the agriculture industry. The results of this study can serve as a reference for governments of Taiwan and other countries.
KeywordsAquacultureLand subsidenceCoastal areaFish farming abandonmentQuestionnaireGroundwater
Land subsidence has become a serious problem along the western and southwestern coasts of Taiwan. It is generally assumed that the subsidence is a result of over-pumping of groundwater by aquaculture businesses. In addition to land subsidence, the over-pumping of groundwater has also caused seawater intrusion, groundwater salinization, seawater overflow, and damage to public facilities along the coast (Lin and Chen 1987; Hsu and Jean 1993; Sun 2004). To resolve the problem of land subsidence, in 1995, the Ministry of Economic Affairs (MEA) and COA jointly initiated the “Land Subsidence Prevention and Treatment Implementation Program” (LSPTIP) (MEACOA 1995) to reduce groundwater consumption primarily through a reduction in the area of land devoted to freshwater aquaculture. This program proposed to develop aquaculture districts (mainly along coastal areas), as well as seawater pond culture and coastal cage culture. To concentrate fish culture operations and reduce their spread, fish ponds lying outside the aquaculture districts, mainly freshwater ponds, were to be changed for other uses. The program aimed to further reduce groundwater consumption through encouraging the development of local tourism and fingerling culture. This program was mainly policy oriented, and did not target the root cause of land subsidence, and therefore did not achieve tangible results (Yang 2001; Sun 2002, 2007).
Average productivity (kg/ha) from shrimp culture in major shrimp-producing countries
This study reviews current government policies for preventing land subsidence and presents a new set of solutions to solve this problem. This study began in 2005 and continued until 2009. A total of 82 questionnaires were collected. This study attempts to determine why the current government policies are ineffective, and presents feasible solutions. The results and proposed solutions of this study can be used as a reference for the governments of Taiwan and other countries for aquaculture development and coastal management.
Land subsidence in Taiwan
Taiwan is narrow and elongated from north to south, with a high Central Mountain Range (CMR) from which most major rivers flow westward. The rivers are generally short and flow rapidly to the ocean during the rainy season, and surface water does not persist long enough to seep into the ground. In addition, most precipitation occurs in the rainy season between May and October. Despite abundant rainfall, Taiwan suffers from water shortages, ranking 18th worldwide in terms of severity (Hsu 2000).
Consumption levels of groundwater in recent years in Taiwan (units: 106 m3)
Groundwater consumption, groundwater supplementation, and over-pumping quantities in western and southern Taiwan in 2002 (units: 106 m3)
Joushou plain (western Taiwan)
Jianan plain (southwestern Taiwan)
Pingtung plain (southern Taiwan)
Many studies have pointed out that fish culture activities along the coast are the main cause of land subsidence on the western and southwestern coasts of Taiwan. Huang (1987) pointed out that groundwater consumption by aquaculture is responsible for up to 75% of land subsidence. In his master’s thesis, Chang (2004) concluded that the relationship between the rate of land subsidence and the area used for aquaculture was statistically significant (at p < 0.05). Studies by Lin and Chen (1987), Sun (2004), and Chen (2005) pointed out that the over-pumping of groundwater by coastal aquaculture activities was the major cause of land subsidence along most of Taiwan’s coastal areas. Liu et al. (2003) pointed out that seawater intrusion in the coastal area of Yunlin County was caused by the over-pumping of groundwater.
Although public opinion and most studies consider aquaculture activities to be the main cause of land subsidence, agricultural groundwater use is more than double that of the aquaculture industry. In 1990, agricultural use of groundwater totaled 2.96 × 109 m3, or 47.27% of annual groundwater consumption, while the aquaculture industry accounted for 1.57 × 109 m3, or 25% (Chu 1991). By 1999, agriculture used 3.009 × 109 m3, or 53% of total groundwater consumption, while aquaculture only used 1.294 × 109 m3 or 23% (Lee et al. 2001). In the Yunlin area in 1989, agricultural groundwater use was 0.706 × 109 m3, while aquacultural use was only 0.2 × 109 m3 (Yang 2001). Consumption of groundwater by industry and households also contributes to the problem. Coastal industrial development, which causes land subsidence, seawater intrusion, and environmental contamination, is an increasingly serious problem that urgently needs to be addressed (Lee et al. 1998; Shan 2005; Liu et al. 2006; Yang 2007).
Aquaculture developed early in southwestern Taiwan, as much of the land was unsuitable for crop farming. The Taiwanese aquaculture industry developed rapidly between 1971 and 1987, when Taiwan was experiencing rapid industrialization and economic development. Improvements in aquaculture techniques and the expansion of foreign markets made the aquaculture a profitable industry, encouraging further rapid expansion. In the same period, a decline in conventional agriculture led to many farms being converted to fish ponds, especially in the southwest. Initially, government agencies were only concerned with increasing production levels and paid little attention to the planning or regulation of the industry, leading to large increases in the number of illegal aquaculture ponds.
Pond areas expended rapidly. In Yunlin County in 1971, 1981, and 1991, freshwater ponds covered 860, 2323.2, and 3649.73 ha, while brackish-water ponds covered 505, 1444.2, and 3965.15 ha, respectively (Yang 2001). This expansion was supported by a dramatic expansion of the number of wells. In 1967, the total number of wells in Linbian and Jiadung, two districts of Pingtung County, was 242, but by 1980, it was 1,401, of which 1,276 were for aquaculture use. However, most of these wells were built without permits (Lin and Chen 1987).
The total cumulative subsided land area in Taiwan has reached 1,941 km2 (Chang 2004), or about 20.5% of the total plains area of 9489.90 km2 (EPA 2007). It is clearly a serious problem. The large scale of illegal aquaculture ponds, especially along the coast, makes this problem difficult to manage and regulate. Government agencies, considering the livelihoods of illegal fish farm owners, gave into the reality and established many aquaculture districts, mainly constituting illegal fish ponds along the coasts, while at the same time, promoting seawater pond aquaculture, coastal cage culture, and aquaculture tourism in an effort to reduce the severity of land subsidence.
Materials relevant to aquaculture development policies, coastal management policies, and programs related to these policies, along with executive reports, academic study results, opinions about these policies and programs, and other documents related to aquaculture development and coastal management studies, were collected from journals, theses, government reports and yearbooks, proceedings of seminars, symposiums, workshops, magazines, and websites in both Taiwan and other countries.
Framework of the study
Relevant documents were collected and reviewed which were then divided into different categories based on policy topics (coastal subsidence prevention, aquaculture district establishment, or aquaculture development). A set of questionnaires was distributed to ascertain the opinions of aquaculture industry operators to the above-mentioned government’s policies. Conclusions were drawn and suggestions were formulated based on a combination results of the literature review and the questionnaire analyses.
The questionnaire covered the interviewee’s basic demographic information (name, address, telephone number, gender, age, educational level, and profession), opinions on the government’s land subsidence prevention and treatment policies, opinions on the aquaculture district and its performance, and overall evaluation of government aquaculture policies and its performance in resolving subsidence problems. The questionnaire was tested with five people, three of them were farm owners, and then modified. An appointment with each interviewee was made in advance, and the interview was conducted in person.
The interviewees were divided into three categories: fish farmers, officials, and academics. The fish farmer group consisted of fish farmers and business people working within the aquaculture industry. One person from each farm or business was interviewed. Most of them were owners (88.9%) and the rest were main operators. Businesses within the aquaculture industry included fish feed manufacturers, aquaculture drug salespeople, and businesspeople involved with fish storage, packing, and selling.
Basic information of the interviewees
Fish culture–related business
Senior high or professional school
Since all of the interviewees of the official and academic groups had a BS degree or higher, bias resulting from educational background was avoided by attempting to interview farm owners with a higher level of education. Thus, 38.2% of the farmers included had earned a BS degree or higher, which is much higher than the typical educational background of aquaculture farmers, of whom only 6.0% have a BS or higher academic background (Chen and Liu 2004). Consistent with the concentration of aquaculture, most of the interviewees were located in central and southern Taiwan.
Percentile method (frequency distribution): The frequency of each answer to each question chosen by the interviewees in different categories was determined, and differences among the three categories were calculated for each answer.
Reliability test: The reliability of the results was tested using Cronbach’s α coefficient (SPSS, Chicago, IL, USA) (Wu 2005). According to this test, for the total scale, a value of >0.8 is good and a value of 0.70–0.80 is acceptable. As for the score scale, the α value should be >0.70. A value of >0.80 is good, and a value of 0.60–0.70 is acceptable. In this study, the α value of “Effects of government land subsidence prevention and treatment policy” was 0.67, that of “Opinion on the establishment of aquaculture districts” was 0.82, that of “Overall opinion of government aquaculture policy” was 0.80, and that of the total scale of the questionnaire result was 0.78.
Validity evaluation based on a content validity evaluation: The questionnaires, designed based on the main problems of the industry, were pre-tested by conducting interviews with academics and experts in the aquaculture industry, and were modified after the interviews. This was done to ensure that the contents of these questionnaires were pertinent, could accurately express the opinions of members of Taiwan’s aquaculture industry, and could be used as an important part of this paper.
Method used to determine significant differences among categories: The analysis of variance (ANOVA) method was used. In cases of significant difference, Scheffe’s method was used to determine the extent of the difference. Statistical significance was set at p ≤ 0.05.
Results and discussion
Evaluating the performance of the Land Subsidence Prevention and Treatment Implementation Program based on a literature review
The LSPTIP’s goal is to reduce over-pumping of groundwater by the aquaculture industry. Reducing groundwater consumption by industry is not central to the main theme of this program. This paper mainly concentrates on evaluating the performance of various goals set by the LSPTIP in terms of reducing groundwater pumping by the aquaculture industry. Analysis of the LSPTIP’s goals and its results are presented in the following sections.
Evaluating the results of establishing aquaculture districts
In addition to causing land subsidence, the wastewater discharged by these densely distributed fish ponds also has several adverse impacts to the ecology of coastal areas. As mentioned in reports by Sun (2002) and Dalman et al. (2006), nutrients, organic matter, and copper ions in the wastewater from fish ponds have contaminated the environment, a situation that has often occurred in aquaculture. Currie (1994) reported that almost all coastal aquaculture results in contamination of the surrounding marine areas. Contamination caused by wastewater discharged from shrimp ponds in Asia and South America has long been a controversial topic (Phillips et al. 1993).
Aquaculture districts can affect the development of other businesses inside the district. This may cause problems of whether these aquaculture districts can survive in the future (Liu 2008).
Evaluating the effect of readjusting the proportion of the aquaculture industry
Evaluating the effects of promoting seawater pond culture
Hsu and Jean (1993) suggested stopping the promotion of seawater pond culture along the coast to avoid causing the salinization and contamination of groundwater in coastal areas. In 1986, Lin and Chen (1987) suggested setting up a freshwater reservoir or canal as a buffer zone between agricultural and aquacultural areas to avoid soil salinization. However, fisheries authorities (FA and COA) failed to follow their advice when promoting seawater pond culture along the coast. It is necessary to pump freshwater groundwater to adjust the salinity of seawater ponds, resulting in further land subsidence. Therefore, promoting seawater pond culture in coastal areas only makes the situation worse.
Evaluating cage culture development
Cage culture has developed slowly in the Taiwan Strait due to rapid currents, typhoons, and frequent mudflows and landslides. Cage culture can only be set up in embayments or near the shore resulting in adverse impacts on the fishery industry and coastal ecology (Chen and Hsu 2006; Huang et al. 2008).
Stickney (2002) reported that offshore cage culture causes environmental contamination, damages the benthic ecology, and creates a favorable environment for seaweed growth. According to Asche et al. (1999), inevitable escapes of fish from the cages increase the prevalence of disease in wild populations, and reductions in the wild salmon catch were partially attributed to salmon cage culture.
Evaluating other associated regulations, measures, and activities specified in the Land Subsidence Prevention and Treatment Implementation Program
Promoting super-intensive indoor water-recirculating culture systems for European eel (Anguilla anguilla) failed due to high production costs, which are much higher than that of the water flow through highly intensive culture systems for this fish using mountain creek water in China. Transforming inland fish farms into tourist aquaculture areas was also unsuccessful, mainly because of their remote locations, inconvenient transport, and poor landscapes. Programs to promote the production of fingerling or ornamental fish failed because of inadequate demand (Sun 2003).
Evaluating the results of the Land Subsidence Prevention and Treatment Implementation Program in preventing and treating land subsidence
Large-scale declines in groundwater consumption in recent years have reduced the rate of continually subsidence in coastal areas. However, this was not the result of the LSPTIP, which had only a very limited impact (Sun 2002; Sun et al. 2007). From 1991 to 1998, eel and black tiger shrimp production dropped by 38,400 and 5,567 tons respectively. With 22.76 m3 of groundwater needed to produce 1 kg of eel and 17.70 m3 to produce 1 kg of shrimp, this drop in production represented a decrease in groundwater use of 9.74 × 108 m3 (Sun 2004), from a total decrease in groundwater use of 12.41 × 108 m3 during this period (FA 1999). Thus, this decrease was mainly due to the declining production of shrimp and eel, two cultured species that consume the most groundwater. The decline in shrimp production was due to disease; for eel, it was due to a decline of foreign markets (Lee et al. 2001; Sun 2004).
Chen (2005) pointed out that the key reason for increased land subsidence around Syuejia Township in Tainan County was a change in the type of fish farming employed. Similarly, a report from the Hydrotech Research Institute of National Taiwan University (2007) indicated that the area of land subsidence around Dacheng Township of Changhua County had increased in recent years because farmers had switched to higher-value species such as the golden freshwater clam. In both cases, the conversion was from relatively water-thrifty aquaculture species or types to those requiring considerably more water. Therefore, although the area experiencing continuous subsidence has decreased, this decrease was mainly due to economic reasons (Lin and Chen 1987; Chen 2005). Without proper official guidelines, land subsidence will worsen again once the structure of aquaculture farming switches to a type requiring more groundwater.
Even if the area of continuous coastal subsidence is reduced, the cumulative subsided depth will still increase. In areas where fish farms are concentrated, such as Jiadung District of Pingtung County, in the beginning of the LSPTIP in 1995, the subsidence depth was 2.82 m but had increased to 3.24 m by 2006; the maximum cumulative subsidence depth on the coast of Changhua County in 2001 was 2.02 m, and that in Yunlin County was 2.10 m. However, by 2008, cumulative subsidence in these two areas had increased to 2.52 and 2.4 m, respectively (Water Resources Management and Policy Research Center 2009).
Grouper production is concentrated in Jiadung and Linbian Townships, which are already below sea level, but two aquaculture districts were still established on the Jiadung coast. On August 8, 2009, typhoon Moraket hit southern Taiwan, causing seawater to overflow and nearly destroy grouper farming in Taiwan (Taipei Times 2009). This indicates that, aside from causing land subsidence, the establishment of aquaculture districts along the coast may have exacerbated existing overflow problems.
Areas of coastal counties still threatened by continued subsidence in Taiwan (units: km2)
Evaluating the performance of the Land Subsidence Prevention and Treatment Implementation Program based on questionnaire results
Responses to questionnaires about the adjustment of the structure of the aquaculture industry and prevention and treatment of land subsidence
High percentages of respondents agreed that the government fisheries authorities (FA and COA) lack a feasible policy to treat or prevent land subsidence: 82% of the fish farmer group, 60% of the official group, and 83% of the academic group shared this viewpoint.
Reducing groundwater consumption, and thus preventing further land subsidence, requires the development of a simple and feasible water-recirculating culture system for coastal pond aquaculture. Percentages in agreement were 78% for the fish farmer group, 89% for the official group, and 89% for the academic group. The majority of the interviewees commented that it all depended on the feasibility of the system.
In reference to “Replacing aquaculture ponds with coastal cage culture and super-intensive indoor recirculating aquaculture systems to reduce groundwater consumption,” although fish farmers do not have the capability to follow those systems, yet the official group approved both systems by 100% and 78%, respectively.
In reference to “Promoting saltwater pond culture along the coast to replace inland freshwater pond culture to reduce groundwater consumption”, both the fish farmer and academic groups felt it was unfeasible (with only 47% and 33%, respectively, supporting it); yet the official group’s approval rate reached 70%.
Responses regarding the establishment of aquaculture districts
Of the official group, 60% agreed that establishing 50 aquaculture districts primarily of saltwater farms but abandoning the remaining mainly freshwater fish farms would strengthen the competitiveness. This contrasted sharply with the fish farmer (29% agreement) and the academic group (18% agreement).
As to “Establishing aquaculture districts can reduce pumping of groundwater and prevent further land subsidence”, 70% of the official group agreed (very effective or effective), which was much higher than the agreement among fish farmers (51%) and academics (45%).
The relationship between fish farmers and district management committees was not very close (only 17% of fish farmers felt the relationship was close), while 77% of the fish farmers inside the districts surveyed felt that the planning and functioning of the districts were unsatisfactory.
Responses regarding the overall evaluation of government aquaculture policy
Approval ratings of the government’s aquaculture policy (including excellent, good, and acceptable) were 23% of the fish farmer group, 90% of the official group, and 50% of the academic group. The fish farmer group’s negative appraisal was in stark contrast to the predictably positive official evaluation of government policy.
In regard to comprehensibility of the government’s aquaculture policies, only 26% of the fish farmer group said that they clearly understood or understood the policies, as opposed to 60% for the official group and 73% for the academic group.
Regarding the “future production plans”, 67% of fish farmers wanted to maintain their current production level; 14% favored expanding production, while another 14% favored reducing production, and 5% favored a temporary or complete end to aquaculture production.
Significance analysis of the questionnaires
Significance analyses of the differences of the questionnaire results among the 3 groups of the aquaculture industry
Questions on the questionnaire
About “Establishing aquaculture districts”
Agreed that setting up 50 sea water-based aquaculture districts can strengthen competition
Officials > academics
About “Overall comments on government aquaculture policies”
Feasible aquaculture policy exists
Fish farmers > officials
Comprehending various current government aquaculture policies
Fish farmers > academics
Conclusions from the responses
Analysis of the questionnaire results indicates that the three groups involved in aquaculture, i.e. fish farmers, officials, and academics, agreed that fisheries authorities (the FA and COA) lacked feasible policies to prevent or treat land subsidence.
Among farmers within the districts, 77% said that the design and function of the districts were inappropriate. They also felt that the relationships between farmers and the district management committee were not close. As for the effectiveness of the programs to eliminate land subsidence, 51% indicated they felt the programs had been successful, when in fact they had not, most likely as a result of government propaganda that promoted the programs as being successful.
The opinions of the academic group largely conformed with those of the official group, but based on a significance analysis, the academics still did not agree with the official group that setting up 50 aquaculture districts would strengthen Taiwan’s competitive edge in the aquaculture industry.
Only one-quarter (26%) of the farmer group understood the government’s policies for the aquaculture industry, which is highly skewed to the low side and is an unfavorable condition for policy implementation.
Among the farmer group, 81% indicated that they would like to either maintain or expand the area under aquaculture, and only 5% wanted to cease or suspend production. This indicates that the current problems related to aquaculture industry, such as land subsidence, are likely to continue unless effective programs are devised and fulfilled.
Analysis of why policies to prevent land subsidence and protect coastal environments was ineffective
Based on the above literature review and analysis of the questionnaire results, it is clear that coastal land subsidence is closely related to the fact that aquaculture ponds are too concentrated along the coastal area. The so-called aquaculture districts are merely official constructs, which not only lack the functions that the LSPTIP proposed, but are actually causing continued land subsidence problems because the districts do not have a supporting freshwater source, but most species cultured in coastal ponds still need more than 80% freshwater, which has to be pumped from underground. Thus, the Aquaculture Act (Chiang et al. 2006) drafted by the FA, which mainly governs the operation of fish farms located inside the aquaculture districts, cannot be expected to resolve coastal subsidence problems either. Furthermore, the LSPTIP program conflicts with the existing “National Land Restoration Strategic Program and Action Plan” (CEPD 2006). Reducing inland aquaculture ponds, while retaining most coastal ponds and establishing aquaculture districts, was the wrong approach for resolving the coastal land subsidence problem. Associated measures, such as developing seawater pond culture, still require groundwater and cause soil salinization, while promoting coastal cage culture creates environmental pollution and also damages the coastal ecology.
The most effective measure to reduce further coastal land subsidence would be to reduce groundwater consumption by taking fish ponds along the coast out of operation. In the 1960s, Japan conducted an integrated emigration program including land-based fish farmers. In addition, the total area devoted to eel culture in Japan has fallen in recent years, but production levels have remained constant through technical improvements. These measures served to reduce the amount of land devoted to fish culture, thus reducing over-pumping of groundwater and preventing coastal subsidence. Thailand is another example. In the 1990s, a serious disease broke out among cultured shrimp. In response, the Thai government limited total shrimp pond coverage to 76,000 ha, promoted recycling aquaculture systems, and relocated some shrimp ponds to reduce their density in coastal areas. These actions have helped the industry work toward achieving sustainability (Lin 2006).
According to the questionnaire responses, most fish farmers acknowledged that the fisheries authorities lack effective policies to resolve land subsidence problems. The results from the questionnaires and interviews were in close agreement with the conclusions from the literature review.
Resolving coastal land subsidence problems and instituting good coastal land management by only reducing groundwater consumption by aquaculture activities are not enough, because the amount of groundwater in Taiwan used by agriculture is at least twice the amount used by aquaculture (Chu 1991; Lee et al. 2001; Yang 2001; Sun 2007). Increasing numbers of industrial parks in coastal areas are also an important source of land subsidence and pollution (Liu et al. 2006). Land subsidence at an offshore industrial infrastructure complex in Yunlin County was caused by over-pumping of groundwater (Liu et al. 2006). Liu et al. (2001) pointed out that both aquaculture and industry are the main factors causing land subsidence in the Yunlin area. Yang (2007) pointed out agriculture, aquaculture, and industry along the coast are not only the main sources causing land subsidence in Yunlin and Chiayi Counties, but also contribute heavily to soil and groundwater salinization. Chang et al. (2004) indicated that over-pumping of groundwater inside the Jungli Industrial Park of Taoyuan County, northwestern Taiwan, was the chief factor for land subsidence. Shan (2005) pointed out that, due to contamination of groundwater by agriculture and industry, farmers and industrial operators have to dig deeper and deeper wells to find uncontaminated groundwater; this cycle will continue to deplete groundwater resources. Lin (1996) concluded that the activities of industry and business have changed not only the face of Taiwan’s coastline, but also its tidal regimes. In addition to land subsidence problems, Lee et al. (1998) indicated that pollution from industry and coal and nuclear power plants has caused heavy metal contamination along the coast of Kaohsiung City, and this contamination has spread to the south as far as the Fengkong River estuary of Pingtung County.
Thus, though reducing groundwater consumption by aquaculture can substantially contribute to controlling land subsidence and seawater intrusion problems along the coast, but the problems cannot be solved by this measure alone. Controlling groundwater pumping by agriculture and industry, in addition to that by aquaculture, is necessary to completely root out these problems. Aside from land subsidence problems, controlling pollution to avoid contamination of the coasts is also an important issue for Taiwan.
The results from this research reinforce the conclusion that the coastal subsidence problem stems mainly from the over-pumping of groundwater, based on short-term economic targets and expectations. Currently, there is no effective enforcement of aquaculture or industrial policy and no policy for long-term coastal development and protection.
The government needs to create a high-level inter-ministerial team to substantially reducing fish pond coverage in subsiding coastal areas. The team should evaluate the performance of the Council of Agriculture, the Fisheries Agency, the Ministry of Economic Affairs, and the Industrial Development Bureau in establishing policies and practices to reduce coastal subsidence.
The high density of aquaculture ponds along the coast has caused significant land subsidence, and fisheries authorities (FA and COA) should change their existing policies of reducing inland fish ponds and maintaining most coastal ponds. The fisheries authorities should endeavor to reduce pond areas. Coastal aquaculture ponds, especially in areas with serious subsidence, should be reduced on a large scale, and those ponds in areas of low subsidence need to be fitted with recirculating systems to reduce their groundwater use. At the same time, the promotion of seawater pond culture and offshore cage culture should cease, lest it contribute to negative environmental impacts.
To reduce coastal pond culture, fisheries authorities should take all necessary steps to avoid protests from farm groups. Previous events such as protests of Hung Mao Kang Fishing villagers against mandatory relocation (Wu 1998) and fishermen’s resistance against the establishment of offshore industrial complexes (Tang and Tang 2006) proved difficult to manage. Rather, the government should initiate legal procedures to encourage the closing of fish farms by setting up a “Fish Farming Abandonment Programs” to compensate farmers and assist them with job training to find employment in other fields, and to put the abandoned fish farms to other uses.
Based on the results of Yang’s questionnaire (Yang 2010), given appropriate compensation and occupational training, 66.1% of fish farmers would like to leave or would consider leaving fish farming. Chang (2004) found the percentage willing to leave the industry was 73.73%. These results indicate that such a program may have a good chance of success. After fish farmers sign an agreement to quit fish farming, their ponds will be filled with earth and their wells sealed. The farmers will still own the land, and the government will help them to develop their land to provide local residents with much improved living conditions, and also provide suitable conditions for further development of the coastal area. Otherwise, those areas (including coastal ponds) will eventually be submerged below sea level.
The cost of this program would be NT$ 16 billion per year for ten years and would result in most ponds in subsided coastal areas being filled in, and more than half of the farmers (mostly in coastal areas) leaving the fish farming business (Sun 2010). The current four-year budget for flood control and prevention is in excess of NT$300 billion and does not address the issue of reducing total pond area to diminish coastal subsidence (Sun 2010).
New aquaculture enterprises will not be encouraged, and any new aquaculture activity will be limited to existing ponds. To conserve groundwater, eel, a high-groundwater-consuming cultured species, should not be cultured in coastal areas.
After the culture area is substantially reduced, legal procedures must be established and implemented to guide the industry, thus ensuring the sustainable development of the industry, so that it is in accordance with the “National Land Restoration Strategic Program and Action Plan” to protect coastal areas.
In addition to regulating the aquaculture industry, it is necessary to manage and reduce groundwater use by agriculture and industry. Agriculture uses twice as much groundwater as aquaculture; thus, it is necessary to take all measures of water conservation approaches, such as the development of irrigation water and wastewater recycling, and low-cost water storage methods such as using deepened rice fields and fallow fields as reservoirs (Chang 2001; Water Resources Agency 2002). Adjusting the agricultural structure to reduce groundwater use should be another approach (Yeh and Tung 2003; Sun et al. 2007).
As for conserving groundwater in the industrial sector, recycling waste water (Wenzel et al. 2002) will not only save groundwater, but also prevent contaminants from flowing into rivers and the sea, thus reducing harm to the coastal ecology. In addition, it is important to explore new surface water resources, such as building more reservoirs.
The most important point is to use detailed planning, evaluation, and verification before constructing any big factories or commencing any large-scale land development projects or water-consuming projects along the coast.
This study reveals that Taiwan lacks feasible coastal land subsidence prevention and treatment programs.
The current program to establish large-scale brackish-water and saltwater aquaculture districts along the coast has had negative environmental impacts, has done little to resolve the ongoing problem of coastal subsidence, and contradicts the “National Land Restoration Strategic Program and Action Plan” in terms of revitalization and protection of land affected by subsidence. Most subsiding areas along the coast coincide with concentrations of fish farming ponds, and the cumulative depth of subsidence in many areas is still increasing, and some areas may experience seawater overflow during typhoons or heavy rainfall. Such factors may derail the development of coastal regions, and it is necessary to gradually dismantle the coastal aquaculture districts to reduce environmental impacts by first reducing the number of coastal aquaculture ponds and rescinding the policy of maintaining coastal aquaculture districts. An “Fish Farming Abandonment Program” should be established to implement the above measures. Based on the results of this study, this program stands a reasonable chance of success.
The consumption of groundwater for agriculture and industry is also closely linked to land subsidence and therefore should be included in the scope of the LSPTIP to fully protect coastal lands from further subsidence. A water recycling system should be established to help achieve this goal, which would also help decrease water contamination problems along the coast.
A high-level inter-ministerial team should be organized to effect substantial reductions in the coverage of coastal ponds and diminish land subsidence.
The results and suggestions of this study can serve as a reference for government both in Taiwan and abroad for aquaculture industry development and coastal management.
The authors would like to thank the members of Taiwan’s aquaculture industry who participated in the questionnaire interviews.