4.2 Fishing

Until the early 20^th century, fishing in Loreto was practiced only in inshore areas with small vessels powered by oars and sail. The main fishing technique utilized in the early 1900’s was hook and line. In the 1930’s new technology was introduced: outboard motors and gillnets. Fishing became a major driving force for regional development in the 1950’s; however over-exploitation of the fishing stocks is now becoming a limiting factor for the success of the regional fisheries (Carvajal et al., 2004).

Great fishing effort is dedicated to coastal fish species to meet the increase in demand for fish, resulting in unsustainable commercial fishing along the coasts of the Baja California peninsula (Ezcurra, 1998). This increase in demand is driven by a combination of factors including population growth, increase in tourists’ demand for fish associated with an increase in per capita wealth, and the commercial expansion of regional fisheries (Young, 2001). Growth in tourist and resident populations in the Loreto region will likely result in an increase in demand for fish, therefore causing an increase in fishing activities within the marine park’s boundaries to meet the demand (FAO, 1998, 2000; UNEP 2002; Boshnakova, 2004). There is a positive relationship between landings and number of visitors in the area (Fig. 4), which suggests that an increase in the tourist population will cause an increase in catch, or at least in fishing effort.

As the fleets of both commercial and artisanal fisheries begin to grow, there will be an increase in fishing effort, intensifying pressure on local fish stocks that already display signs of overexploitation (Wielgus et al., in press; COBI, 2005). The best-known examples of unsustainable fishery management are two groupers: the Gulf grouper (Mycteroperca jordani) and the Leopard grouper (M. rosacea) (Sala et al. 2004, Wielgus et al. in press).

The Gulf grouper used to be very abundant and presently is considered threatened, with its population down to only a small percentage of what it used to be in the 1940’s (Sáenz-Arroyo et al., 2005a,b). Reports dating back to the early 1900’s describe the Gulf grouper as a dominant species in reef ecosystems, and a 1937 description of sport fishermen easily catching giant groupers seems almost impossible to recreate (Sáenz-Arroyo et al., 2005a). The Gulf grouper was targeted by local and regional fisheries and, contrary to what government statistics suggest, natural stocks may have collapsed in the early 1970’s (Sáenz-Arroyo et al., 2005b).

The Leopard Grouper, M. rosacea, is a species that harbors importance on different levels: ecological, economic and as a fishery. It is a top predator on rocky reefs and forms spawning aggregations, particularly in offshore islands (Allen and Robertson, 1998; Sala et al., 2003). This grouper is the most abundant and intensely fished grouper in the Gulf of California. Its economic importance lies in the value of its meat, considered to be of great quality (Randall et al., 2005; Aburto-Oropeza et al. in revision).

Leopard grouper biomass has decreased in the last years with the increase of landings within the boundaries of the marine park (Fig. 5). The extreme value in 2004, when the landings exceeded 60,000 kg, was related with a great recruitment year four years before (Aburto-Oropeza et al., in revision). According to a recent study, the abundance of M. rosacea has decreased inside the marine park where fishing is allowed (COBI, 2005). The average size of the species has also decreased within the park boundaries in relation with the fishing pressure estimated by number of boats per square kilometer (Sala et al., 2004).

Most of the grouper fishery takes place during their reproductive peak when they form aggregations yielding large catches with little effort. Although its abundance has been decreasing, the leopard grouper represents 17% of the overall catch and 94% of the groupers caught in the artisanal fishery inside the Marine Park (Randall et al., 2005). One modeling study indicates that under current fishing conditions, leopard grouper populations in three islands in the park (Coronado, Danzante, and Montserrat) may remain sustainable, but that the population in Carmen Island is not sustainable and will decline if fishing pressure continues at the present rate (Wielgus et al., in prep.).

Recruitment patterns are important to take into account in conservation strategies because a good recruitment season will be reflected later on the adult population size. In the case of the Leopard grouper, larvae prefer shallow boulders (less than 5m depth) covered with Sargassum, a brown alga, as their recruitment habitat. This alga grows seasonally, forming a belt along rocky shores and reaches its maximum growth and density in May and June. Larvae have a settlement peak that matches the Sargassum biomass maximum, and they stay in shallow habitats for their first year after settling (Aburto-Oropeza et al., in prep.). There is a relationship between the variability in Sargassum biomass and oceanographic conditions, such as El Niño events. During El Niño years water temperature increases and nutrient concentrations in the water decrease, affecting the biomass of Sargassum and causing a reduction of the suitable nursery habitat for Leopard grouper recruits. This is reflected in a smaller cohort of individuals that will later (3 to 4 years) recruit to the adult population, and the smaller amount of fish available for the fishery. The opposite pattern occurs in La Niña conditions (cold water, high nutrients), when the recruitment events can be two orders of magnitude higher (Aburto-Oropeza et al., in revision), and four years later is reflected in successful fishing year such as 2004.

Coastal development, through modification of the coastline, and pollution can result in the alteration of areas that can serve as potential recruitment habitat. The two major critical habitats present in the Loreto region are mangroves and Sargassum beds. There are only a small number of mangroves left in the area: as small patches on Carmen, Coronado and Danzante, and larger ones in San Bruno, Nopoló and Puerto Escondido. The last two locations have already suffered great modifications in their coastline since they have become sites of major tourist developments.

Although the data discussed above for Loreto are at a very small spatial scale, the trends are consistent with more regional scale analyses. Studies show that some commercially important species have decreased in abundance and density over the last 30 years or so as a result of increasing fishing activities (Sala et al., 2004; COBI, 2005). Fisheries in Baja California Sur showed an increasing trend in catch 1950-1980, but a decreasing trend in catch-per-unit-effort (CPUE) after 1980. The only group that does not show this decreasing trend in CPUE is the multi-species category of groupers (Sala et al., 2004). However, the fluctuation of CPUE in multi-species groups is due to the shift in target species over time. Big groupers such as Jewfish, Gulf grouper and now Leopard grouper, have been replaced by small Serranids such as sand basses (Paralabrax spp.) and Pacific creolefish (Paranthias colonus).

The creation of the marine park resulted in restrictions and regulations of fishing activities. However, local fishermen comment on how during the last 20 years the most prized species have been overexploited. This overexploitation is mainly due to the use of unsustainable fishing techniques and illegal fishing activities by both commercial and sportfishing industries. Park managers need to work towards more rigorous control of fishing activities within the boundaries of the protected area.