Key constraints and problems affecting the inland fishery value chain in central Mexico

Abstract

Anthropogenic activities have been the major cause of watershed deterioration in many parts of the world, negatively impacting inland fisheries. In Mexico, freshwater fishing represents a source of protein, income, and employment for rural communities; however, in the national fisheries statistics they only account for 3% of the total production, and increases have not taken place since the 1990s. Demand is higher than supply because the national market can only provide 50% of consumption, and these fisheries are currently passing through a complex situation that prevents an increase in production levels and fishers’ incomes. This study examined the main production constraints and problems that prevent production from increasing to satisfy national demand. We considered value chain analysis and fish catch dynamic approaches. Fieldwork was conducted in 2 periods during 2011 and 2012 in 4 riparian communities near Lake Chapala and Lake Yuriria. The methodological approach considered socioeconomic factors and temporal variability of catch volume in both lakes. Results showed that production constraints are the result of watershed and fisheries mismanagement. Catch levels were strongly related to the environmental conditions of the lakes, which have shown instability and decline that affect fishers’ livelihoods. In addition, illegal, unreported, and unregulated (IUU) fishing and the ineffectiveness of institutions to rule the actions of all actors who intervene in the management and use of these resources allow destructive strategies toward the fisheries. Finally, inland fisheries management is not considered part of watershed management policies, resulting in ill-adapted water allocation policies that affect fisheries production levels.

Key words:

• fish value chain
• inland fisheries
• Lake Chapala
• Lake Yuriria
• Mexico

Human activities have induced major negative impacts on inland waters over the past 100 years, and the resulting hydrological alterations pose threats to inland fisheries (Dudgeon 2000, Welcomme et al. 2010). The factors identified as global threats to water basins, including infrastructure, climate change, water over-extraction, introduced species, overfishing, and pollution (Dudgeon 2000, Allan et al. 2005, Wong et al. 2007, Welcomme et al. 2010, Béné and Friend 2011), have also been identified in the Lerma-Chapala basin, Mexico, as factors affecting freshwater fisheries biodiversity and productivity levels (Tereshchenko et al. 2002, Moncayo et al. 2012).

Low productivity in inland fisheries can be a problem for rural areas because these fisheries represent a source of employment, income, and dietary protein (Béné and Friend 2011, Welcomme 2011); however, the lack of documentation to establish their socioeconomic significance diminishes interest by policy makers to implement development plans (BNP 2009). A lack of understanding of the role of inland fisheries in livelihoods has caused policy makers to prioritize other sectors and allow losses of inland fisheries production (Welcomme et al. 2010).

Several studies and reports discuss the complex situation inland fisheries are experiencing worldwide that affect catch levels. The drivers affecting inland waterbodies, such as land-use practices and demand for water, affect fisheries sustainability and diminish the ability of lakes and reservoirs to provide biological and socioeconomic services (Welcome et al. 2010). These drivers also prevent improvement or maintenance of fish production levels, which in turn affect fishers’ livelihoods. Inland waters and inland fisheries in Mexico are not exempt from these hurdles. According to the National Fisheries Chart (Carta Nacional Pesquera; DOF 2012), inland fisheries catch currently represents 2–3% of the total national fishing production. Rojas-Carrillo and Fernández-Méndez (2006) reported that in 1983, inland catch reached 7.41% of the national total, but since the 1990s this volume has not exceeded 3%.

Figure 1 Location of Lake Chapala and Lake Yuriria in central Mexico.

Considering this general scope, we employed a value chain analysis approach and fish catch dynamic analysis as a complementary tool to examine main production constraints and problems in freshwater fisheries that prevent production from satisfying national demand in Mexico. To fulfill this objective, the fish value chain from 2 study areas (each included 2 communities) was identified to describe the main stakeholders and the flow of products. Next, the main factors affecting the different actors and the flow of products in the value chain were identified and analyzed, as well as how catch dynamics are linked to these factors. This information could provide insights into the general dynamics of inland small-scale fisheries as part of inland water management in Mexico.

Study site

Lake Chapala is the largest lake in the country and the third largest in Latin America. It measures ∼72 × 22 km² (114,659 ha), has a storage capacity of 7897 × 10⁶ m³, and is considered a shallow tropical lake (Tereshchenko et al. 2002). This lake is shared by 2 Mexican states: 86% of its surface is in Jalisco and 14% in Michoacán (Fig. 1).

Lake Yuriria was originally an area of wetlands that in 1548 was converted to an artificial reservoir. Currently, this lake regulates the water levels of the Lerma River, the main water source for Lake Chapala. Lake Yuriria is one of the most important waterbodies of the state of Guanajuato and one of the 10 largest waterbodies in Mexico (Fig. 1), with a surface area of ∼4800 ha and a storage capacity of ∼288 × 10⁶ million m³ (CONAGUA 2011).

Fisheries

Fishing in Lake Chapala has been a traditional activity since pre-Hispanic times. From colonial times to the 19th century, there was a high regional demand for fish, motivated by the abundant native species such as pescado blanco (Chirostoma lucius), popocha (Algansea popoche), and mesa silverside (Chirostoma spp). In Lake Yuriria, fishing became a traditional activity when the wetlands were converted into a lake. Today the main fisheries from both lakes are tilapia (Oreochromis spp.), carp (Cyprinus spp. and Carassius auratus), and mesa silverside. Common carp (Cyprinus carpio) was introduced in Mexico in 1884 with the intention to create a strong aquaculture industry. At the same time, the government established fish hatcheries to produce fish fry, which were introduced in most natural and artificial waterbodies in the country. Tilapia was introduced in 1964 as a food security and economic development strategy for rural communities (Rojas-Carrillo and Fernández-Méndez 2006), and, similar to carp, tilapia was introduced in most inland waterbodies in the country. In Lake Chapala, tilapia catches appear in the records beginning in the 1970s.

Since 1930, the introduction of carp and tilapia fish stocking has occurred systematically with the construction of hydroelectric infrastructure (Carranza-Frazer 1953). In other words, every time a dam was constructed, carp and tilapia were introduced, and hatcheries or government-funded freshwater fish farms (GFFF) were created (Ibáñez et al. 2014). Currently, inland fisheries management is mostly based on fish stocking from the 14 GFFF in the country, and 90% of fry production is carp and tilapia. Fish fry can be obtained from the GFFF by application; however, clear specifications or guidelines do not exist.

Environmental degradation and the establishment of exotic species have been suggested as the main causes of native species reduction in Lake Chapala; in 2000, 11 native species had disappeared from the catch (Moncayo et al. 2012).

Lake declines

Lake Chapala's history of changes and decline started with the construction of a hydropower plant in 1894 to provide the city of Guadalajara with electricity. In 1903 the powerful hacendados (landlords) from the region developed plans to embark and drain the marsh area. This process was completed in 1910, and an area of 50,000 ha was drained; since then, these lands have been used for cattle farming and agriculture. As a result, the first Lake Chapala water crisis occurred between 1945 and 1958, aggravated by a period of lower levels of rainfall and water extraction for hydropower generation and irrigation (Wester 2009). Furthermore, in 1956 an aqueduct to supply water to the city of Guadalajara was constructed. Currently, Chapala sources 60% of the increasing water demand for the city.

Lake Yuriria forms part of a wetland network, most of which has been destroyed by anthropogenic activities such as agriculture, urban expansion, or other industries. Today only 10% of the original wetland area subsists. Most water from this lake is allocated for irrigation, causing low water levels, and 245.83 L/s of wastewater is discharged into the lake.

Both lakes form part of the Lerma-Chapala basin, one of the most important hydrological systems in the country as well as the most heavily populated (23.29 million people) hydrological region in the country. This basin contributes 18% of the national GDP, and 30% of industrial activity depends on its resources (CONAGUA 2013).

The Lerma-Chapala basin supports about 3500 industries, including metal and mechanical, leather, electro-mechanical, paints, batteries, chemical, petrochemical, and mining (Hansen and van Afferden 2001), many of which release waste into the water basin. Studies analyzing factors that deteriorate the water quality in Lake Chapala and Lake Yuriria found sediments and heavy metals at concentration levels that depend on water levels (Hansen and van Afferden 2001, López-López et al. 2011). Eutrophication is another problem, promoting the bloom of water hyacinth in both lakes. Chapala has had periods when water hyacinth covered large areas, and about one-third of Lake Yuririas’ surface is always covered by this plant.

Moreover, 552 dams and ponds along this basin alter flow and decrease inflow from Lerma River to the lakes (Cotler and Gutiérrez 2005). Aparicio (2001) reported a Lerma-River inflow during 1922–1969 of 1646 hm³ with an average annual rainfall of 706 mm, and during 1970–2001 reported an inflow of 738 Mm³ with an average annual rainfall of 697 mm.

Recovery

Both lakes are classified as RAMSAR sites. Lake Chapala has not yet been declared a national protected area, but actions taken for its rehabilitation consist of identifying the main pollution sources, developing a waste management plan, and implementing local environmental regulations (Gutiérrez et al. 2008). Lake Yuriria has been declared a national protected area and has a management plan for its recovery, encompassing the rehabilitation of land, water, and vegetation (Sandoval 2004). Two of the most important actions taken are a sewage treatment plant, built in 2010, and a plan to make the irrigation system more efficient.

Water management

In Mexico, water regulations are part of the National Water Law (Ley de Aguas Nacionales), and the river basin councils are in charge of water management. The federal government has the right to concede surface water-use rights to users for periods between 5 and 30 years (DOF 2014) because surface and ground water are considered national property. The water management policy framework assigns most water for irrigation and secondly for urban use (76.7% irrigation, 14.5% urban use, 4.9% electricity, and 4% other industries; CONAGUA 2011). Inland fisheries management is ruled as a separate activity and is not included as part of water basin management.

Concepts and applications of value chain analysis

The value chain analysis (VCA) approach was first proposed by Porter (1985) as a key tool to better understand all the elements that constitute a firms’ competitive advantage. Porter conceptualized the value chain as a group of activities performed to design, produce, market, deliver, and support a product considering the financial perspective of value creation. Since then, this concept has evolved and been adjusted and applied to better understand the factors that might constrain the function and performance of many different types of industries and economic activities.

More recently, a value chain has been defined as the required activities and services to move a product from producers to consumers, adding value to the product in each link (Hellin and Meijer 2006). VCA is a diagnostic tool that attempts to understand and describe the operations involved in the value chain and provide a multidimensional assessment of the performance of a value chain, which might well include the analysis of product flows, information flows, and the management and control of the value chain (El-Sayed et al. 2015).

VCA has been applied to analyze and describe different perspectives of fisheries. Some studies have explained the crises in the capture fishing sector (Wilkinson 2006) to better understand the pond fish farming value chain (Macfadyen et al. 2012), to comprehend gender participation in the fish value chain (FVC; De Silva et al. 2012), to examine how income changes impact the welfare of fishers (Jiménez-Toribio and García-del-Hoyo 2006), or to identify the risks that trade can pose to valuable ecosystems or the advantages it can generate for local fishing communities (Macfadyen et al. 2003).

For governments, use of VCA can be 2-fold: to monitor and update their knowledge on the fishing activity to facilitate policymaking and the implementation of management plans (Wilkinson 2006); and to improve the value chain performance by implementing specific policies needed to regulate the fishing activity (Macfadyen et al. 2012), which might become part of inland water management. Therefore, the value chain can be traced to different sources and applications (Hellin and Meijer 2006).

Considering each link of the chain from sourcing to the making of the product and to the distribution–selling process, the VCA approach can be an adaptable and useful tool to elucidate the dynamics of freshwater fisheries and to identify and describe the activities and complex environment that characterize the fishery sector. In this study, we used a VCA to examine the inland fishery value chain in terms of mapping product movement by identifying the different phases that fish follow to reach different markets and to outline the fishery- or watershed-related factors threatening each link of the FVC. This analysis was conducted through the breakdown of fishing activities from harvesting to marketing the fish (Macfadyen et al. 2012), and catch dynamics were used as a complementary tool of VCA to explain fish trends and dynamics. In other words, catch dynamics show the variability in catch, which is an indicator of the current conditions of fisheries (Arreguín-Sánchez 2006) and explains production variability.

How fish flow from fishers to consumers depends on the context of where the fish are caught, the type of fish, the factors that determine production and distribution dynamics, and the actors involved in the related processes. In addition, fish production depends on the ecology of each species because inland fisheries are part of freshwater ecosystems.

Materials and methods

Fieldwork

The study was completed in 3 phases. Secondary sources of information were compiled including statistical databases on fish volume and lake water levels from the Secretariat of Agriculture, Livestock, Rural Development, Fisheries and Food (SAGARPA) and the State Water Commission (CEA). Fieldwork in the lakes was conducted during 2 periods: June, August, and November 2011; and September, October, and November 2012, in Lake Yuriria and Lake Chapala, Mexico. In both periods we conducted field trips to learn about the communities, observe the fishing activity, and assess the lake conditions. The work included interviews with fishers, fish traders (middlemen), and restaurant owners in 2 communities from each lake.

Interviews

The first step in designing the interviews and determining the main problems affecting the FVC was through the breakdown of the inland FVC activities, identification of the actors that intervene in each part of the chain, and observation of the general context of the fisheries. During the first visits, we conducted informal talks with fishers to learn who could provide information about the general conditions of the lakes and the fishing activity. We then selected key informants on the basis of their formal roles and status in the community and/or fishing activity (Bernard 2006) and interviewed each to determine the main characteristics of the local fishing activity and to obtain data to draw a survey strategy to interview fishers.

Once we knew that this FVC was a compound process, comprising basic traders such as fishers, middlemen, fish traders, and restaurants, we designed a questionnaire to identify the factors affecting the FVC along the pre-harvest, harvest (catch), and post-harvest activities.

The questionnaires covering qualitative and quantitative issues were drafted before key informant interviews and were finalized after the interviews. The questionnaires were divided into sections to identify the factors affecting each link of the FVC, including (1) catch volume, (2) fishing techniques, (3) transformation and trading activities, (4) selling prices, (5) the main fishing-related problems, and (6) the main problems in the lakes and how they affect the fishing activity. Questionnaires were mainly addressed to fishers but were also adapted to middlemen and local restaurant owners.

The number of fishers in each community was taken from the registers of fishing cooperatives. The 2 communities from Lake Chapala comprised 310 fishers and from Lake Yuriria 316. We interviewed 70 in Chapala and 56 in Yuriria, representing a sample of 22 and 17% of registered fishers, respectively (Table 1). Illegal fishers would not consent to be interviewed and, according to key informants, might represent between 20 and 50%, depending on time of year. The number of people fishing can vary depending on (1) time of year: during warmer months fish production is higher and includes more people fishing than during winter; (2) water level: a low water level makes fishing more difficult; and (3) the number of illegal fishers (obtainiing a fishing permit is necessary to belong to a cooperative) whose appearance is opportunistic: they fish when the fishing season is good or when they need to feed their families. The registered fishers are those socially recognized by the community as fishers.

Table 1 Total number of interviews by actor type to find out the main problems affecting the value chain in Lake Chapala and Lake Yuriria. Communities: La Palma and Petatán, Lake Chapala; and Yuriria and La Angostura, Lake Yuriria. The interview period was between April to November 2012 and April 2013.

	Lake	Lake	Mercado
Interviews	Chapala	Yuriria	del Mar	Total
Fishers	70	56
Restaurants	3	9
Middlemen and market sellers	1	5
Fillet facilities	4	0
Cooperatives chiefs	2	5
Town chief	1	0
Town historian	0	1
Fisheries officials	2	2
Wholesalers			5
Total	83	76	5	166

Table 1 provides information of the total number of individuals interviewed for each lake.

A final set of interviews was conducted in the second biggest fish market in Mexico, El Mercado del Mar, located in the city of Guadalajara. Here, the president of the market and 4 of the main wholesalers of freshwater fish were interviewed about supply problems, trade dynamics, and consumer preferences for this type of fish. The data allowed us to identify and classify the main factors affecting the inland FVC and to describe the value addition and trading patterns. For the calculations, we considered the average price per kilogram of tilapia, the dominant fish in both lakes.

Catch dynamics

Data for both lakes used in the temporal catch variation analysis were obtained from the state fisheries offices (past 13 years), Guzmán (1995, 2002), and directly from the cooperatives’ files and middlemen selling controls. Temporal catch variations were analyzed to identify possible patterns or trends that might reveal current conditions of these fisheries. Trend analysis considered the catch index proposed by Arreguín-Sánchez (2006), which expresses catch rate change as: (1)

where CI_a is the catch index, C_a is the catch level in year a, and C_ā is the average catch during the studied period. A catch index value (CI) of zero indicates no change in 1 year in relation to the average. Assuming from the description by Arredondo-Vargas et al. (2013) that the fishing effort has been increasing through time and the fishing resources are being exploited at a level close to the maximum biological yield, the CI dynamics can be considered a global indicator of biomass trends and thus can be a coarse indicator of the state of the resource. Also, because there is no well-established stocking program and fish stocking has been rare in the last years (twice in the last 10 years in Lake Chapala; Fisheries Office of State of Jalisco), fish production in the 2 study sites can be considered to be based primarily on natural reproduction.

Figure 2 Factors affecting the fish value chain.

CI was estimated in a global form and for each individual fishing resource was reported in the database for mesa silverside, blue tilapia, and carp (Hernández-Montaño 2006, Arredondo-Vargas et al. 2013). Mesa silverside and pescado blanco are native species, but pescado blanco is no longer individually reported in the national statistics.

Because it has been established that the water quality of Lake Chapala can be significantly determined by water levels (Lind and Dávalos-Lind 2002), a Pearson correlation analysis was used to analyze catch relations through the catch index considering water level fluctuations from both lakes, with a statistical significance of α = 0.05. Lake Chapala water level fluctuations (2000–2012) were taken from the Jalisco State Water Commission (Comisión Estatal del Agua de Jalisco). The historical registers of cotas (water levels) are specifically designated for the lake (cota from 100 m = 1526 m a.s.l.) and are generally reported twice a year (Jul and Nov). For our analysis, a yearly cota was estimated considering the average of both measures. Lake Yuriria water levels (2000–2006) were taken from the state fisheries office.

Results

Local value chains

Three main patterns of value chains were observed. (1) The fishery plays a subsistence role when the fisher's family consumes part of the catch and the fisher or his wife sells the rest to a final consumer. This is the shortest value chain and time period from harvest to consumption. (2) The fisher sells the fish by the lakeshore to an intermediary (middleman or restaurant), who then sells it to a final consumer. (3) The third case is a longer and more complex value chain, in which the fish passes through more intermediaries: middlemen (who in Chapala fillet the fish), to a wholesaler, to an urban market, and, finally, to a consumer. In Lake Chapala the value chain is longer because middlemen have facilities to fillet, wash, and pack the fish, transformation processes that are unavailable in Lake Yuriria.

Different value chains ranging from household-based to commercial are due to communities’ socioeconomic conditions and geographic locations. In our study we found that communities with access and connections to larger cities, as well as to other economic activities, are limited. Moreover, the complexity of the value chain organization also depends on fish availability and the transformation processes applied to fish.

Figure 3 Problems identified by the fishers affecting pre-harvest activities.

Major impact factors

Factors affecting the FVC identified through the interviews and questionnaires applied during the fieldwork (Fig. 2) are presented and explained considering the stages that comprise the FVC: pre-harvest, harvest, and post-harvest.

Table 2 Tilapia average prices during fish trading transactions between fishers and chain members in the selected communities; value addition and final price percentage received (Mexican pesos).

	Average price per kg of tilapia		% of final consumer price
Sub-sector	Lake Chapala	Lake Yuriria	Lake Chapala^*	Lake Yuriria^*
Fishers	6 (0.46 USD)	8 (0.6 USD)	9%	13%
Middlemen	30 (2.30 USD)	12 (0.92 USD)	52%	20%
Rural markets	25 (1.92 USD)	50 (3.85 USD)	42%	83%
Restaurants	135 (10.5 USD)	150 (11.5 USD)	225%	250%
Supermarkets	60 (4.61 USD)	60 (4.61 USD)	100%	100%

^*Value chain average price when fish passes through these actors

Pre-harvest affecting factors

The identified factors affecting pre-harvest activities related to lake conditions are water pollution and eutrophication, water allocation, and competition with other economic activities. Fishers mostly reported that lake problems such as water pollution and water discharges affected fishing (Fig. 3). In Lake Chapala, fishers explained that water discharges come mostly from riparian communities, and most water treatment plants in the area are dysfunctional.

Fishery-related factors such as the introduction of exotic species and fish stocking were identified by fishery officials as elements affecting the fisheries and lake biodiversity. The introduction of exotic species was not identified as a problem by the fishers, however, even though introduced carp and tilapia currently represent 88.1% of total catch, and fish production depends on stocking. The fishers recognized fish stocking as a problem in Lake Chapala because it has only occurred on the Jalisco side of the lake, creating more rights for those fishers. In Lake Yuriria, fish cooperative chiefs assured that fish stocking could take place when requested by a government hatchery, which has occurred up to 3 times per year.

Competition with other economic activities resulting from water allocation policies was indicated by fishers who reported that they never participate in water management meetings organized by the local irrigation office, and that most water is assigned for irrigation. Thus, fishers think that those who normally decide water usage are mostly in agriculture.

Harvesting affecting factors

The fishery-related factors that affect harvesting activities identified in the interviews are illegal, unreported, and unregulated fishing activities (IUU); overfishing; and violation of state line boundaries. Cooperative chiefs expressed illegal fishing as a major concern because it stimulates overfishing and, particularly in Lake Yuriria, is a source of social conflict. Fishers also reported overfishing as an important problem in the lakes (Fig. 3). In both lakes, overfishing is a consequence of the type and increasing amount of fishing gear and mesh sizes that have been or are being used. The use of seine nets by illegal fishers, although forbidden, seems to be the main source of overfishing. Fishers mentioned that this diminishes the quantity and size of fish harvested. At the same time, however, they also affirmed that “using smaller mesh sizes is the only way we can catch something.” Crossing state boundaries to fish is also a source of conflict with fishers in the neighboring state because they limit free access in Lake Chapala.

Under-reporting was also identified as an important problem by fisheries officials, who noted that Lake Yuriria fishers only report about 50% of real catch volume and Lake Chapala fishers about 40%. In addition, officials added that fishers’ cooperatives often report the whole catch as tilapia without separating it from other species.

Lake problems for harvest mentioned by the fishers are water levels and water hyacinth, which can even prevent fishing activities (Fig. 3). In Lake Yuriria, water hyacinth makes navigation impossible and carries away gill nets.

Key informants expressed their concern about water mismanagement as an important cause of low water levels. In Chapala, some fishers switch to agriculture on the exposed land when water levels are low and fish become scarce, yet few fishers perceived water level fluctuations as a problem. In Yuriria the fishers indicated that shallow water might mean higher catch levels for a period of time because fish concentrate in smaller areas.

Post-harvest affecting factors

The main factors affecting post-harvest value chain dynamics can be explained through processing and marketing activities, most of which are fishery related rather than external or concerning watershed management factors. Transformation processes are important components of value addition (Table 2). In Lake Chapala, most middlemen fillet the fish, dry the mesa silverside, and sell it to a final consumer or to other middlemen, whereas in Yuriria most fish are sold whole and fresh. Fish processing creates jobs and is an extra or even main source of income for women and some young men in these rural areas.

During fieldwork we observed that fish are processed under poor hygienic conditions; the local infrastructure does not include cooling systems, and even ice is uncommon. Despite these problems, losses of fish are rare, even for longer time periods between harvest and consumption.

Middlemen dominate most trading transactions, and most fishers rely on them to take the fish to urban or local markets, the most common pattern in both lakes (Table 3). Although selling fish to a middleman might be the easiest and faster trading strategy, it also leaves fishers with the lowest percentage of the final price (Table 2).

Table 3 Trading patterns between fishers and chain members.

Lake	Middlemen	Restaurant	Local market
Lake Chapala	95%		5%
	60%		40%
Lake Yuriria	68%	32%
	80%	10%	10%

The choice to sell the fish to middlemen or in different markets depends on the fisher's ability to generate the necessary income to acquire preservation or transportation facilities needed to take fish to rural markets. Moreover, trading patterns are also affected by the communities’ geographic locations. Two of the studied communities do not have arable land because they are located between the lake and the mountains, and other economic activities have not been developed, making them more dependent on fishing. In these communities, more fishers search for different markets to obtain higher prices. Communities with access to other economic activities most commonly sell the fish to middlemen because their income derives from both fishing and farming, making them less dependent on fishing. Middlemen rarely report their sales. At least 50% of the catch is sold directly to local consumers, creating an informal trading system. Only fish going to urban markets are documented by an invoice provided by the cooperatives.

Exotic species also affect fishers’ income and catch volumes because native species have higher market prices. Fishers receive US$0.38–0.53/kg for tilapia and carp from middlemen, while for pescado blanco they receive $11.50–15.00/kg. In addition, the native fish do not pass through middlemen, and although this provides an opportunity to obtain higher prices, this fish is scarce (0.01% of the catch). The combination of low prices and low-value fish force fishers to try to increase catch volume to supplement their income.

According to the fish market sellers in the city of Guadalajara, the most consumed fish in the country is tilapia, and local sales in the studied communities are also dominated by tilapia. However, the public perception of pollution in the lakes impacts the sale of the fish. The interviewed restaurant owners or local market traders affirmed that when consumers are aware of the lakes’ pollution problems, they are not willing to buy the fish and ask instead for farm-raised fish.

Catch dynamics

Blue tilapia, carp, and mesa silverside were the most important fishing resources in both lakes, together accounting for 99.9% of total catch. Catch in Lake Chapala is dominated by tilapia, accounting for 54% of total catch, while in Lake Yuriria carp dominates catch volume with 51% (Fig. 4).

Figure 4 Main fish resources in Lake Chapala (2000–2012) and Lake Yuriria (1992–2012).

In Lake Chapala, tilapia catch increased beginning in 2003, reaching a maximum in 2006; from 2006, a marked decline began and persisted until 2012 (Fig. 5). In Lake Yuriria, a decreasing trend was observed in catch levels through the 1990s. Tilapia and mesa silverside catch levels had a stabilizing trend at ∼100 tons per year from year 2000. In the case of carp, the decreasing trend was observed until 2006, when catch levels stabilized at 300 tons per year (Fig. 5).

Figure 5 Annual catch trends in Lake Chapala and Lake Yuriria fisheries.

Variation of each fish resource in total annual catch was as follows: in Lake Chapala, tilapia accounted for the highest catch level each year, with a total average of 50%. Only in 3 of 13 years of our analysis was the tilapia catch lower than carp (2001, 2002, and 2012). In 2002, tilapia catch levels were lower than mesa silverside, with only 22% of the total catch level (Fig. 6). In Lake Yuriria, carp accounted for the highest catch levels, with an average of 53% of the total catch. The carp catch level was >50% for 15 of the 21 analyzed years (Fig. 6).

Figure 6 Catch trend participation level by species in Lake Chapala and Lake Yuriria fisheries.

The catch index was calculated for the 3 most important species from each lake, first collectively and then individually (Table 4). Results indicated that the studied period in Chapala can be divided into 3 phases. The first phase, from 2000 to 2003, is a low catch period with all negative index values, indicating below average catches. During the second phase, from 2004 to 2010, the catch index shows a stabilization period in which the catch level was higher than the average each year. Finally, in a third phase from 2011 to 2012, the index decreased drastically in 2012, reaching the second lowest value during the whole study period (Fig. 7). In Lake Yuriria, a decreasing trend was observed (P < 0.05) from the beginning to the end of the studied period. The catch index was positive each year from 1992 to 1999 and negative from 2000 to 2012 (Fig. 7).

Table 4 Catch Index in Lake Chapala and Lake Yuriria.

	Lake Chapala				Lake Yuriria
Year	Global	Blue tilapia	Carp	Mesa silverside	Global	Blue tilapia	Carp	Mesa silverside
1992					0.7944	0.8269	0.6612	1.0202
1993					0.7063	0.8288	0.4576	1.0076
1994					0.5145	0.6268	0.3626	0.6783
1995					0.4109	0.5544	0.2115	0.6147
1996					0.0674	0.1337	0.1361	−0.2336
1997					0.1658	0.6268	0.0241	−0.4531
1998					0.0935	0.1601	0.2367	−0.5188
1999					0.1340	0.0585	0.2835	−0.2048
2000	−0.6511	−0.7688	−0.3279	−1.4971	−0.1312	−0.3166	0.0338	−0.3578
2001	−0.9963	−1.3611	−0.5019	−1.5250	−0.3961	−1.7583	0.0286	−0.7168
2002	−0.7089	−1.6205	−0.5228	0.4453	−0.2229	−0.6273	0.0668	−0.6683
2003	−0.4665	−0.6431	−0.5423	0.1910	−0.3155	−0.3501	−0.2312	−0.4949
2004	0.1894	0.4288	−0.2180	−0.1599	−0.2686	−0.3701	−0.2282	−0.2395
2005	0.3456	0.5238	0.0523	0.1560	−0.3959	−0.6187	−0.3371	−0.2822
2006	0.5436	0.6354	0.2475	0.8037	−0.5787	−0.5220	−0.6632	−0.4696
2007	0.4462	0.5239	0.3207	0.4114	−0.5035	−0.4873	−0.4876	−0.5650
2008	0.5397	0.4792	0.6720	0.3986	−0.2963	−0.3973	−0.2709	−0.2325
2009	0.1587	0.1101	0.2966	−0.0767	−0.3121	−0.3689	−0.2892	−0.2945
2010	0.1937	0.1442	0.3606	−0.1593	−0.3642	−0.5571	−0.3077	−0.2746
2011	−0.4944	−0.5604	−0.3480	−0.6567	−0.4578	−0.6598	−0.4447	−0.2665
2012	−0.9868	−1.2070	−0.6170	−1.4433	−0.5060	−0.6307	−0.5239	−0.3256

Figure 7 Catch index in Lake Chapala and Lake Yuriria fisheries.

The correlation analysis between the catch index and the water level fluctuations showed significant correlations for the estimated catch index for the 3 major fish species in Chapala, and particularly for mesa silverside in Yuriria (Fig. 8). Overall, when the water level was low, the index presented the highest negative values, and when the water level increased, the catch index also increased. In addition, from the water level correlation with the different catch indexes in Chapala, we observed that no positive value from the catch index was found when the water level was <1438.71 m a.s.l. (Fig. 8).

Discussion

In this study we identified some of the major factors that negatively impact inland fishery production levels, and we used a VCA approach and a fish catch dynamic analysis to examine how these factors affect production in freshwater fisheries in Mexico. Through the breakdown of the fishing activities as indicated by the VCA approach (Hellin and Meijer 2006) and the complementary tool of analysis catch dynamics, we found that external factors, lake conditions, and fishery-related problems affect the pre-harvest, harvest, and post-harvest activities in the FVC from both lakes. The water management, pollution, and fluctuation problems affecting pre-harvest, harvest, and post-harvest fishing activities result from various causes, as explained in the lake decline section. In both lakes, diminished water quality can affect the biotic integrity and promote the bloom of water hyacinth, leading to higher rates of evaporation (Moncayo et al. 2012, López-López et al. 2011). Water hyacinth is always present in both lakes and can prevent fishing by impeding navigation and carrying away gill nets. In 2010, researchers from a local university declared that they found heavy metals in Lake Chapala, which affected fish trade from this lake. Their findings support fishers’ declarations.

According to Welcomme et al. (2010) water allocation policies become a stress factor for inland fisheries sustainability when fishing must compete for water with other economic activities. In both lakes, water level fluctuations occur due to over-extraction, decreased inflow from Lerma River, and decreased annual rainfall. These factors, combined with the increasing number of people living in the area, are the main reasons to classify the basin area among the most heavily populated and polluted regions in Mexico (Sedeño-Diaz and López-López 2007). These factors also negatively impact the quality and quantity of water for freshwater fish production and explain why major threats to inland fisheries are external to the fisheries sector and are related to watershed problems and water mismanagement (Welcomme et al. 2010), providing evidence that specific policies are needed to improve the fishing activity (Macfadyen et al. 2012).

Figure 8 Correlation between water level and catch index in Lake Chapala using the general catch index and in Lake Yuriria using the mesa silverside catch index.

Low water levels affect the socioecological system because water level fluctuations have a negative impact on fish production (Dudgeon 2002) and, as a result, on fish catch volume, as shown in the catch dynamics analysis. Consequently, fishers must implement coping strategies to adapt their way of living to changes in available lakeshore resources (Sarch and Birkett 2000). In Lake Chapala, farming is possible during dry seasons on exposed land; however, due to its characteristics of deep lake, agriculture is not possible in Lake Yuriria. When other economic activities are unavailable, migration occurs.

The fishery-related factors such as exotic species, IUU fishing, fish stocking, and overfishing also have a negative impact along the value chain. Because carp and tilapia have become the productive base for inland fisheries, about 50% of the native species in Lake Chapala have been displaced (Moncayo et al. 2012). Our analysis indicates that native species catch volume is the lowest for mesa silverside and is insignificant for pescado blanco (0.01%). Currently, Mexico's inland fisheries rely on tilapia and carp, low-value exotic species, and fish productivity is maintained through fish stocking; however, no norms exist to regulate, monitor, or analyze the behavior or impacts of this activity (Rojas-Carrillo and Fernández-Méndez 2006).

IUU fishing activities are recognized as problems affecting fisheries worldwide (FAO 2002). Seine nets were forbidden in the region in the mid-1980s to conserve fish resources. In Lake Chapala, fishing authorities tried to substitute gill nets, but fishers continue using seines or adapted their fishing gear to smaller mesh sizes to fish for juveniles. Illegal fishing is increasing because, for some fishers, it seems to be an adaptive survival strategy to obtain food and generate income, but this continued activity negatively impacts fish production. These adaptive responses to low volume intensify overfishing and illustrate destructive actions by amplifying fishing pressure on the resource. This continued behavior demonstrates that economic poverty, combined with a lack of options and a deteriorated resource base, has led fishers to adopt destructive conduct toward the fishery (Eriksson et al. 2012).

Informal trading through middlemen is a common pattern in fish trading in small-scale fisheries in developing countries. Primary rural producers depend on these intermediaries to take products to markets (Crona et al. 2010, Pedroza 2013) because fishers do not own or have access to preservation or transportation facilities to take fish to markets, allowing middlemen to exert power over fishers and obligate them to sell their products for low prices. This system stimulates illegal fishing and overexploitation because middlemen buy any fish, even if it does not meet legal requirements such as size (Crona et al. 2010, Pedroza 2013), and low prices force fishers to intensify the fishing effort to increase their catch to compensate for low income. The number of gill nets has increased in Lake Chapala from 4600 in 1982 to 80,600 in 2006, and in Lake Yuriria from 14,105 in 2007 to 17,018 in 2012 (DOF 2012).

Misreporting is a historically common issue in fisheries and is even more intense in inland fisheries. This practice affects fishing statistics and obscures the real social benefits provided by this activity (BNP 2009, Welcome 2011). Arredondo-Vargas et al. (2013) affirmed that misreporting in Lake Chapala is about 70%, and fisheries officials confirmed that Lake Yuriria and most freshwater fisheries in the country are likely similar. This lack of reporting has discouraged the government from increasing or maintaining investments in the fishing industry because it is perceived as a low productivity sector. Consequently, informal trade and IUU fishing activities also have a negative impact on inland aquatic ecosystems.

Fish processing is one of the post-harvest activities where value and employment are created and involves more participation by women (Welcomme et al. 2010). Lake conditions, poor hygiene, and preservation, along with small fish size, diminish quality and presentation, however, preventing fish from selling at higher prices in urban markets and competing with fish imports.

Consumer preferences and the import market are external factors also affecting these fisheries. In Mexico, 36% of total fish imports are tilapia fillets from China, and 30% are pangasius fillets from Vietnam (SAGARPA 2012). These fish are normally cheaper and better presented than local tilapia fillets coming from the local lakes, making competition impossible. Imports are needed because national production of freshwater fish only provides 50% of demand. National production of freshwater fish has not had significant increments since the1990s, and freshwater fish annual average production has been 135,000 tons for more than 20 years (SAGARPA 2012). In addition, consumers aware of lake conditions will not buy fish from these lakes, which implies that national efforts to improve production are insufficient to address this resource deficit and the lake deterioration that affect the fish trade.

Conclusion

The main factors affecting fisheries’ production levels can therefore be divided into environmental, fishery–water management, and organizational, all of which affect fish production, harvesting, processing, and trading activities along the value chain. There is a relationship between the biological and social aspect of these fisheries. The catch dynamic analysis demonstrated that the fishery is unstable. Lake Chapala has had periods of bonanza (high catch levels), but a production decline has occurred in the last years, and Lake Yuriria has had a general declining catch volume. These declines and the correlation analysis with the water levels strongly suggest that catch levels are highly related to the environmental conditions of the lakes and have concurrent socioeconomic impacts on fishers. Consequently, inland waterbody deterioration has a negative impact on rural communities’ livelihoods.

Lake management problems such as low water levels and pollution are affecting the catch volume and the quality and quantity of fish, directly linked to a long history of ineffective environmental and fishery management policies. These policies are normally focused on the use of resources such as water for the development of agriculture or livestock, and they poorly regulate the efficient disposal of industrial waste or the administration of water. Inland fisheries management is not included in these lakes’ management plans in particular, or in lake and reservoir management plans in general, because they are seen as independent activities.

All negative impacts on fisheries from these factors are exacerbated by a poorly adapted and applied policy framework with weak policy enforcement that allows IUU fishing activities. The existing institutions are not sufficient to rule the actions and conduct of all the actors that intervene in the management and use of the natural resources that comprise inland fisheries.

The VCA approach, together with the catch dynamic analysis, are useful tools for identifying critical factors that affect inland fisheries and inland waterbodies. The identified factors can be used as a base to implement actions to improve freshwater fish production.

Including fisheries management as part of water and basin management would provide additional elements to establish more suitable water levels to conserve fish production and to set the basis for fishers’ participation in water management. The implementation of sociobiological tools such as VCA and catch dynamics can provide elements about the fishers and the fish to be considered in management plans, such as regulations for fish trade.

Acknowledgments

We thank Jazmín Ibarra Gálvez and María de Jesús Magallón Cruz for their help and collaboration in the fieldwork. The authors acknowledge the valuable suggestions made by the editor and the anonymous reviewers.

Funding

The research in this paper was funded by the Universidad Nacional Autonóma de México (UNAM) through project PAPIIT IB300212.