Freshwater fishes represent among the most diverse and threatened taxa globally, accounting for more than 25% of total vertebrates (> 30,000 species described), 37% of which are threatened with extinction (Darwall et al., 2008; Chapter 1). The poor conservation status of freshwater biodiversity is directly related to the pressure that these systems experience worldwide (Vörösmarty et al., 2010). Because of their importance to human welfare and development, freshwater ecosystems and biodiversity are subject to higher pressures and threats than are adjacent terrestrial ecosystems (Nel et al., 2007). Water pollution and abstraction coupled with invasive species and habitat modification (e.g. channelling and damming) are the principal threats to the conservation of freshwater biodiversity (Strayer & Dudgeon, 2010; Vörösmarty et al., 2010). These pressures are rapidly growing due to the increase of human population worldwide and the effect of climate change (Dudgeon et al., 2006; Chapter 3).
Although freshwater ecosystems and biodiversity are in urgent need of protection, there has been little emphasis on declaring protected areas for the primary purpose of conserving freshwater biodiversity (although see attempts in South Africa since the early 1970s (Roux & Nel, 2013 for a brief history) or the USA (Moyle & Yoshiyama, 1994)). Instead, uninformed opportunism has reigned, whereby the conservation of freshwater ecosystems has remained peripheral to conservation goals developed for terrestrial ecosystems, unless considered important for terrestrial biodiversity (Nel et al., 2007; Olden et al., 2010). The implementation of conservation is constrained by limited budgets and potential conflicts with other human uses. For this reason, it is unfeasible to protect all the areas that contribute to the persistence of biodiversity (Margules et al., 2002), and adequate planning is required. Conservation planning is a discipline that tries to deal with these issues to inform stakeholders and decision-makers on how to best invest limited resources available for conservation. The development of a conservation plan typically draws on knowledge spanning several scientific disciplines, increasingly also from the social sciences.
To be effective for freshwater conservation in general and fish in particular, protected areas must consider some particularities of freshwater ecosystems from the early planning stages (e.g. when deciding where to implement conservation) to the daily management. Freshwater ecosystems pose some unique challenges to the implementation of effective conservation (Abell, 2002), such as the importance of connectivity at maintaining natural processes and facilitating the propagation of threats (Linke et al., 2011).