Pressure indicators

Catch, fishing effort and discards in the country’s fisheries

Fish catch might become a highly detrimental activity for fish stocks when performed improperly (FAO, 2009). Some of the most important consequences of overfishing are the loss of the fishery’s productivity and commercial extinction (Goñi, 1998; Jackson et al., 2001). This may result from the capture’s effects on the three basic features of target species populations: Population size, size structure and reproductive condition. Overfishing reduces significantly the population biomass by removing individuals, which also reduces its genetic variability (Goñi, 1998; FAO, 2003; García et al., 2003; Godø et al., 2003). These effects affect the potential for recovery and long-term viability of commercial fish species populations. Most populations of the ten most heavily fished species worldwide, representing about 30% of the global marine catch, are fully exploited or overexploited among them, the anchovy (Engraulis ringens), the Alaska pollock (Theragra chalcogramma), the blue whiting (Micromesistius poutassou) and herring (Clupea harengus) (FAO, 2009). The indicator National fish catch is used by international organizations (such as the UN, EU and OECD, for example) to analyze and evaluate the fishing pressure and its possible impact on fisheries.

Although the rapid growth of capture fisheries in the world can be attributed to several factors, one of the most important ones is the increase in fishing effort and power, that is, the greater number of vessels with increasingly sophisticated fishing gear (Groombridge and Jenkins, 2002). The indicator National fishing effort, measured by the number of vessels, denotes another component of pressure that the fishing activity can impose on the country’s fisheries. This indicator has been used for management assessment and activity monitoring, as well as for developing policies and programs aimed at the sustainable management of these resources (OECD, 1998, FAO, 2000, CCE, 2003).

Fish discards are a routine operation in many fisheries around the world. It involves returning to the sea those unwanted individuals of the target or other species, often seriously injured, dying or even dead (FAO, 2009). The main reasons for discards are fishing regulations (fish caught are unsuitable because they belong to protected or banned species or their sizes do not fulfill the minimum size provisions of minimum size, etc.), and market conditions (FAO, 2009). From the fisheries point of view, one of the major impacts of this practice is the reduction of the target species population size which, in turn, can reduce its future productivity or even lead to its commercial extinction. The indicator Discards in the major Mexican fisheries denotes the pressure that the unselective capture of target species imposes on their natural populations. However, no data are currently available to compute this indicator for any Mexican fishery.

Coastal development

Coastal areas have become socially and economically important areas in Mexico and around the world. Population growth in coastal areas might affect fisheries (particularly coastal fisheries) due to the increasing demand for fish products and the increased generation of municipal and industrial waste which pollute the waters (Lara-Lara et al., 2009). This leads to the overexploitation of local commercial species stocks, the alteration and destruction of marine habitat, and water pollution, all significantly affecting the structure and function of mangrove forests, estuaries, seagrass beds and coral reefs, habitats that are occupied by many commercial fish species during part or their entire life cycles (GESAMP, 2001; PNUMA, 2007). The indicator Population growth in coastal areas denotes the pressure that population growth might impose on the country’s fishery resources. This indicator is presented in the section on Coastal and ocean ecosystems of the Biodiversity chapter. Population growth rates are also used as pressure indicators in the UN’s and the OECD’s lists of Sustainable Development Indicators, hereby applied to the country’s coastal areas.

Illegal fishing

One of the major problems currently faced by fisheries in Mexico and around the world is illegal fishing. This activity can have severe environmental and socio-economic impacts (CCE, 2002; FAO, 2009). This practice characteristically involves the violation of conservation and management regulations, which is detrimental for both the fisheries and their environment; in addition, the trade of illegally caught products constitutes an unfair competition for those that are legally caught (CCE, 2002; Schmidt, 2004). The indicator Fish products seized through inspection operations denotes the pressure that this practice imposes on the national fisheries.