Introduction

Wild animals have always been utilized as food source for human survival and, as civilizations progressed, the role of animals as a commercial resource has firmly been cemented. Wild life has been extensively exploited as a food source, as much as for commercial means (^{Zhang et al., 2008}; ^{Brooks et al., 2010}); such is the case for sea turtles, which for centuries have traditionally been used as a protein source (meat and eggs) (^{García-Martínez & Nichols, 2000}; ^{Fleming, 2001}; ^{Urteaga & Díaz, 2006}), for traditional medicine (^{Mancini et al., 2011}), ornamentation (^{Nichols, 2003}; ^{Senko et al., 2009}) and for ethnic ceremonial activities (Caldwell, 1962; ^{Felger & Moser, 1987}).

Nowadays, sea turtle populations are affected by different threats like habitat destruction, the negative impact of coastal development to nesting sites, the predation of adults and eggs, the propagation of exotic species, diseases, climatic change and natural disasters (^{Avens & Goshe, 2007}; Vivaldo et al., 2006; ^{Alava et al., 2011}; ^{D’Ilio et al., 2011}; ^{Bolten et al., 2010}; ^{Fuentes et al., 2010}). ^{Gilman et al (2010)}, considered incidental catch in fishing as the main cause for turtle decline in recent times. This is due to the high incidence of poverty in fishing towns, since for the fisherman it represents a very important food/economic resource, this added to the lack of technical resources and adequate materials for fishing.

Ecological-social studies about natural resource management in communities localized within Protected Natural Areas (PNA) are important, since PNAs function as a spatial mechanism of protection that allows the establishment of special measures for the management of wildlife in different habitats, including beaches and adjacent marine zones, in which excessive exploitation of natural resources can break ecological stability; this has caused the dwellers to modify their habits, in order to adapt to the regulations intrinsic to the PNA. Moreover, there’s a lack of information regarding the use and consumption of sea turtles in Sinaloa. These make it important for researchers to acknowledge the perception of fishermen towards these species, given the available evidence of anthropogenic activity as a cause of sea turtle mortality (^{Nichols, 2004}; ^{Aguilar-González, 2009}; ^{Mancini & Koch, 2009}).

In this study we describe the perception of fishermen from the communities of three PNAs from Sinaloa (The Priority Marine Region Bahía de Santa Maria, the Sanctuary Playa Ceuta and the Flora and Fauna Protection Area Meseta de Cacaxtla). We selected these sites, because in Playa Ceuta and in Meseta de Cacaxtla there are campsites dedicated to the protection of sea turtles. Bahia de Santa Maria was selected because is one of the most important areas for bay fishing in Sinaloa.

Material and Methods

Zones of study: The Priority Marine Region “Bahía de Santa María” (RMPBSM) is found within the geographic coordinates 24°43’00’’- 24°25’00’’ N y 107°56’00’’- 108°19’00’’ W, corresponding to a 53 000 ha surface area. Angostura and Navolato municipalities delimit this bay. Bahía de Santa María is the biggest lagoon system in Sinaloa (Figure 1) and is highly relevant in a biological sense, given the huge diversity of species of both flora and fauna, which cohabit within the area. Additionally, it is recognized as part of the North American Migratory Bird Corridor, which is why it has been catalogued as a Priority Natural Area. Fishing is the main source of income for dwellers of the 3 coastal communities studied along the bay: Playa Colorada, Costa Azul and La Reforma (^{Amezcua et al., 2006}; ^{Castillo-Guerrero et al., 2009}; ^{Villalba et al., 2004}).

Figure 1 Geographic location of the Protected Natural Areas of study 

The sanctuary Playa Ceuta (SPC) is located in the central region of Sinaloa, within the Elota municipality; limiting with the mouth of Cospita at the north (24°05’42” N y 107°11’38” W) and the mouth of Elota river at the south (23°52’43” N y 106°55’52” W). This region holds one of the most prosperous valleys in terms of agriculture, livestock and fisheries, since these are the main sources of employment of the 2 studied communities: “Ceuta” and Celestino Gasca (Figure 1).

The Flora and Fauna Protection Area Meseta de Cacaxtla (APFFMC) is considered to be a natural sanctuary that holds a diversity of ecosystems that allow the existence of an important quantity of birds, mammals, fish, amphibians and reptiles, that establish Meseta de Cacaxtla as one of the most biologically-diverse PNAs in the country, as well as the larger PNA in Sinaloa. The plateau holds a surface of 50 862 ha, located at the coordinates 23°29’31’’- 23°47’08’’ N and at 106°29’55’’- 106°48’08’’ W, between the municipalities of San Ignacio and Mazatlán. Fishing is the main source of employment in the 3 surveyed communities: Barras de Piaxtla, El Pozole and Toyua (Figure 1).

Survey data collection: Surveys were carried out according to the method defined by ^{Tambiah (1999)} for the fishermen from fisheries within PNAs, in order to obtain information regarding the perception of each fisherman on the subject of: Socioeconomic status, acknowledgement and state of the art regarding sea turtles, sea turtle capture, consumption habits and bycatch fishing.

The number of individuals surveyed was established by calculating the minimal sampling rate using the finite populations statistic formula defined by ^{Hernández et al. (1998)}: n’= S²/V² (Provisional sample size= sample variance/population variance), where: N= population size, S²= sample variance expressed as the probability of occurrence and V²= population variance (standard error squared).

Surveyed Data Analysis: A database that contained the collected information was established, in which frequency tables were elaborated in order to obtain proportions. To acknowledge the existence of statistically significant differences regarding the perception of the dwellers to sea turtle populations, according to their knowledge and usage of sea turtles, a One-way Analysis of Variance (ANOVA) was applied (^{Zar, 1984}), using the SPSS15.0 software.

Results and Discussion

Of the five species of marine turtles described for Sinaloa, the olive ridley turtle (Lepidochelys olivacea) is the main one identified in the SPC and APFFMC; in the case of the RMPBSM the species with which fishermen are familiar is the brown or green turtle (Chelonia mydas). In the three ANPs studied, the marine chelonians that are less recognized in the region by the respondents are the yellow turtle or loggerhead (Caretta caretta).

Of the 273 survey / interviews conducted with fishermen from the different communities of the three PNA (eight communities in total) the age group of the respondents was 41 to 43 years, the average monthly income was between two thousand and three thousand Mexican pesos; the greater proportion of these belong to a cooperative (labor union) and they fish during the whole year, with the exception of the inhabitants of the “Meseta de Cacaxtla.” According to the context presented in Table 1, the fishermen of the APFFMC do not have the same financial opportunities in comparison with the respondents of the other two PNA; since being a member of a fishing cooperative (labor union) can obtain various federal supports, ease of negotiation in the purchase of fishing equipment and agreements with buyers. Deducing that the “Meseta de Cacaxtla” is the region with less support from the government and therefore the PNA studied more affected economically. This could cause a disadvantage in the knowledge regarding the populations of sea turtles (abundance and identification of species) since there is a significant statistical difference according to the economic situation (gl = 7 Chi²= 155.114 p = 0.05) and age (gl = 7 Chi²= 14,344 p = 0.045), as shown in Figure 2 where the fishermen of the RMPBSM and in the SPC mentioned that the population of sea turtles is less abundant at the moment and the opposite was pointed out in the APFFMC, which they indicate that it is more abundant than previous years, only 5.2 % of the inhabitants do not know how this group of animals is; this observed differences could be due to the years of work in these areas, like in Playa Ceuta, since 1976 (^{Sosa 2007}), which implies a greater vision in the oscillations. For RPBS there are no environmental education work done and it is the most important fishing regions in Sinaloa, hence the fisherman’s perception of abundance and regarding the APFFMC has been working since 2008 only on nesting sites.

Figure 2 Current status of sea turtles according to fishermen in the areas studied 

On the other hand, ^{García-Martínez & Nichols (2000)} allude that a fisherman has greater access to sea turtles by the mere fact of being a fisherman; therefore, they know how the abundance of these is. In this sense, due to the fact that older fishermen have been doing this work for longer, it is expected that they will have greater knowledge about the demographic changes that the sea turtle population has suffered.

45.7 % of the fishermen including the three PNA consider that the current status of sea turtle populations is less abundant; similarly, ^{Aguilar-González (2009)} finds in the San Ignacio-Macapule-Navachiste Lagoon System that belongs to the APFF Islands of the Gulf of California, where he indicates that 72 % of the respondents indicated that the populations of these organisms are less abundant. With the aforementioned study and this one, it covers more than half of the Sinaloa coast and the PNA where sea turtles are geographically distributed. These results showed that the perception of fishermen at state level believes that populations are decreasing.

The information gathered suggests that the decline of sea turtles within the studied areas could be due to illegal fishing and egg consumption mainly, followed closely by incidental fishing (Table 2), this value not being statistically significant (gl=7 Chi²=5.534 p= 0.595). These results agree with what was reported by ^{Mancini and Koch (2009)} in Baja California Sur and ^{Aguilar-González (2009)} for the north of Sinaloa; the less important causes are the diseases that present these marine chelonians and climate, as shown in Table 2.

The capture of marine chelonians was something that could be witnessed among the fishermen surveyed in the study areas, a fact that can be seen in Figure 2. Although 72% of the population has not furtively captured sea turtle species, the economic situation of the fisherman can lead him to capture it. Possibly fishermen with a low family income resorted to the capture of this resource. ^{Mancini et al. (2011)} in Baja California Sur mention that this activity represents an extra profit because the poaching of these species provides more profit than the legal fishing of fish or shellfish. However, Figure 3 shows that in the protected natural areas of Bahía de Santa María and Playa Ceuta, turtle fishing takes place to a greater extent than in the Meseta de Cacaxtla, due to the fact that in these two regions the marine turtles are hunted for pleasure and not by necessity as in Cacaxtla, there being a statistically significant difference in the consumption habit with respect to the locality (gl = 7 Chi²= 24,017 p = 0.001) (Table 3). Also, due to the lack of economic resources, the capture of a turtle represents an opportunity for the fisherman’s family to feed, this in Baja California Sur (^{García-Martínez & Nichols, 2000}). Based on these records, it was highlighted that factors such as monthly income, economic benefit from the sale of this product and tradition are what lead a fisherman to engage in hunting for sea turtles, 100 % of the respondents recognized that this activity is a crime.

Figure 3 Records of poaching in the three study areas 

Table 4 shows the diversity and percentage of sea turtle species hunted in the three ANPs, where it is highlighted that the brown turtle (Chelonia mydas) is the most captured prey by the riparian fishermen in the RMPBSM and consumed mostly in Easter, whereas in the other two regions, it is the fishing season when the consumption of turtle meat is greater, preferably of the olive ridley turtle (Lepidochelys olivacea). These results show statistically significant values (gl = 7 Chi²= 22.785 p = 0.002). In the three PNA there is an illegal trade where the kilogram of meat is commonly sold at 50 pesos and a complete turtle sells for 500 pesos.

The RMPBSM is the area where the highest consumption of sea turtles was recorded, compared to the study carried out by ^{Aguilar-González (2009)} in the San Ignacio-Macapule-Navachiste Lagoon System, where it was observed that 86 % of the fishermen belonging to that site have consumed turtle, marking a preference for the brown turtle (Chelonia mydas); In addition to this, the various studies to determine the mortality of chelonians that have been carried out in Bahía Magdalena indicate that slaughter for human consumption is the main cause of death, especially affecting Chelonia mydas (^{Gardner and Nichols, 2001}; ^{Koch et al., 2004}; ^{Nichols, 2004}; ^{Koch et al., 2006}); this indicates that the inhabitants of the populations near a bay or a lagoon complex develop a greater tendency to consume sea turtles; and that is related to the fact that the brown turtle is the most popular species for consumption since it is the one that frequents this neritic ecosystem (^{Felger & Moser, 1973}, ^{Seminoff et al., 2002}).

The data provided here establishes consumption habits such as major fishing zones, dates and most affected species, providing information needed to design specific strategies for the protection of sea turtles in the areas analyzed.

The main areas where fishermen work in the three regions are in bay, open sea and estuary; in the open sea it is the area where it is recognized that incidental fishing of turtles occurs. The fishing gears used in the three regions studied with which sea turtles are caught incidentally are: bottom and ridged chinchorro, chango, cimbra, cast net, hook and nets; There is statistical significance with respect to the site (gl = 7 Chi²= 45.992 p = 0.001). The bottom hammock (chinchorro) is the fishing gear that mainly causes damage in the three areas, where it is used to capture mainly stingrays, sharks and snook.

They can be highlighted in several studies both in Mexico (^{Koch et al., 2004}, ^{Peckham et al., 2008}, ^{Aguilar-González, 2009}), and in other parts of the continent (^{Ott et al., 1999}, ^{Studzinski et al., 1999}; ^{Rosales et al., 2010}) the interactions of artisanal fisheries with sea turtles, where the main fishing gear that causes the greatest incidence in the capture of turtles are gill nets or chinchorros, which coincides with this study. On the other hand ^{García-Martínez and Nichols (2000)} determined that gillnets significantly increase the demand or supply in fishermen that use it since it is a non-selective tool with which non-target species such as turtles are caught, which makes consumption more accessible.

Conclusions

Based on the results, it can be deduced that factors such as the site or location, age and the economic situation of the fishermen intervene in the knowledge and use of sea turtles in the three Protected Natural Areas studied. In addition, when the economic situation of the fishermen is low, contact with this fauna decreases and, consequently, the general knowledge of the fishermen about the demographic situation of the sea turtle is less.

On the other hand, most of the incidental capture of sea turtles for the three sites was with the bottom hammock (chinchorro), which is used for the fishing of stingrays, shark and snook, so it is necessary to establish management strategies on these fishing gear. In addition, the activities for the protection of sea turtles, which are currently applied in the PNA are not sufficient for the conservation of these from the point of view of the fishermen of the communities. To conserve the biodiversity of a site, first of all, the needs of the inhabitants must be taken into account since they may be offering conservation strategies that mean a significant change in their socio-cultural traditions, which makes their adoption by the community difficult. It is necessary to implement new strategies or redesign existing ones so that the management of wildlife is established, aimed for the rational exploitation and sustainable consumption of these species.