Current situation of the fish fauna in the Mediterranean region of Andean river systems in Chile

1 SUMMARY The low number of native fish species of the Chilean Mediterranean region (27o S to 36o S) is a consequence of its geographic and hydrological characteristics. The area has marked precipitation gradients as a result of both latitudinal differences in precipitation and the higher precipitation at high altitudes in the Andes. The seasonal hydrologic variability characteristic of Mediterranean climatic zones occurs in the area together with inter-annual variations due to El Niño Southern Oscillation (ENSO), a significant oceanic climatic influence which determines lower daily and seasonal temperature gradients compared to similar northern latitudes. River catchment areas above 3000 elevation generate short and torrential channels with high velocity, a snow–pluvial regime without riparian vegetation and high total salinity composition. Only 21 native species have been described in this region. They are important due to their high endemism and primitiveness, along with their biogeographical relations, especially the Siluriforms with the northern tropical fauna and the Galaxiidae with Gondwana fish. Currently 75% of the fish species of this region are classified as endangered or vulnerable according to Chilean regulations. Knowledge of the biology and ecology of these species is still incomplete. The information available is mostly classical morphological descriptions, although recently there have been studies of genetics and speciation. This review describes the current distribution and knowledge of the biology and ecology of the native fauna of the Chilean Mediterranean zone and the main threats for their conservation.


INTRODUCTION
Between 27º and 36º south latitude Chile has a Mediterranean climate, with important latitudinal differences in precipitation among seasons and years due to the effects of El Niño Southern Oscillation [EN-SO, (Niemeyer & Cereceda, 1982)].These natural fluctuations are currently influenced by the effects of climate change on Mediterranean zones, which have serious repercussions on biodiversity (Cowling et al, 1996;Elosegui & Sabater 2009).This is particularly serious for the Mediterranean zone of Chile, which is one of the world hotspots of biodiversity (Myers et al 2000).Terrestrial and freshwater fauna in Chile have high endemism as a result of geological history.The geographic isolation of Chile due to the uplift of the Andes since the Cenozoic Era, the presence of the Pacific Ocean on the west, the desert in the north and glaciers in the south, together with the high natural salt content of the soils of the western mountain slopes, have been the main forcing variables in the structuring of the aquatic communities, which are characterized by low species number and high endemism, with some species restricted to two or three small river basins (Vila et al 1999;Dyer 2000;Habit et al 2006a).A total of 46 fish species have been described for the whole Chilean territory.River hydrology and geology may have influenced the rather small size of the majority of the native species and the capacity of the fish to ascend torrents above 1000 m altitude (Fig. 1), with the exception of those found in systems of the high Andean lands (Vila et al 1999).The geographical relationships of the fish fauna of the Chilean Mediterranean have both a Pacific coast origin in the case of galaxiids and atherinids (Dyer 2000), and a very old relic tropical origin for catfish and characids (Arratia 1997).
In this review, we update the knowledge of the native fish fauna of the Chilean Mediterranean region, describing their current distribution and addressing the main conservation issues and needs for research.

STUDY AREA
Mediterranean river watersheds between 27º S and 36º S in Chile are short, torrential, with steep slopes, no intercommunication, few tributaries and thus of low order.The Mediterranean climate in this region is characterized by a strong latitudinal gradient in precipitation, which together with the altitude generates rivers with a snowmelt-rain regime with significant differences among seasons (Table 1).Precipitations determine winter (June to August) floods and summer (January to March) low flows; snowmelt runoff during spring and the beginning of summer (October to November) produces a second but usually smaller high flow peak.The latitudinal gradient determines increased flows from north to south, varying from 0.10 to 34.8 m 3 /s in the northern Mediterranean region up to 11.20 to 585.1 m 3 /s (Niemeyer & Cereceda 1984;DGA 2013; Table 1).Together with flow, other dependent variables change along the latitudinal gradient, such as an increase in water velocity, lower water temperature and lower conductivity to the South (Leopold 1994;Pizarro et al 2014).pH tends to be basic (from 7.6 to 8.0) in the northern rivers, varying to neutral to the South.The average annual air temperature ranges from 6° C during winter at higher altitudes to 29° C in the lowlands during summer.Table 1 details hydrological and temperature characteristics of the main Chilean rivers.

CHARACTERIZATION OF THE FISH FAUNA
We recognize a total of 21 native fish species from the Chilean Mediterranean region, including two species of Agnatha and 19 Teleosts (Tables 2 & 3).
Agnatha is represented by two species, Geotria australis with a broad distribution in the Southern Hemisphere and Mordacia lapicida, endemic to Chile.Both species are anadromous and parasitic when adults.
Teleostei is represented by different orders; Siluriforms are the richest group in the region.Arratia (1990) cited 32 families of Siluroidei for South America, but only three of them are present in the Mediterranean region of Chile.Catfish of the family Trichomycteridae are species with strongly compressed body, three pairs of maxillary barbells reaching the tip of the interopercular spines and small body size (seldom reaching 30 cm total length).Trichomycterus inhabits the dead zone of rhithronic river areas with high oxygenation and coarse substrate of boulders or gravel (Arratia, 1983a,b).Trichomycterus areolatus Valenci-ennes (Figure 2) is the species of this family with the broadest distribution in Chile, inhabiting along the entire Mediterranean zone.It spawns during the austral spring (Manríquez et al 1988;Chiang et al 2011a, b).The maximum total length of mature fish is 56.7 mm for males and 51.1 for females.During spawning the mature oocytes are bright yellow and their diameters range from 1.5 to 2.1 mm (Manríquez et al 1988).
Their feeding habits are benthic, consuming preferentially aquatic insects such as chironomid Diptera, Trichoptera and Ephemeroptera (Scott et al 2007).Trichomycterus chiltoni has only been described in the Biobío River basin.Its reproductive behavior is unknown; however, mature females have been observed in spring.It has benthonic feeding, consuming especially aquatic insects and juveniles of the crustacean Aegla (Arratia 1983b); it has a wide trophic superposition with T. areolatus (Scott et al 2007).The last species of this family is Bullockia maldonadoi, which is found in the potamon zone of rivers; it is characteristic of the Coast Range, particularly the Cordillera de Nahuelbuta (Oliver, 1949;Habit & Victoriano 2005).Bullockia maldonadoi (Figure 2) changes its habitat Fish fauna in the Chilean Mediterranean region DOI: 10.29094/FiSHMED.2015.002 during development from a sandy substrate to one composed mainly of gravel and small rocks.It is also found in riparian ponds with macrophyte vegetation (Arratia, 1983a).It is a small fish which usually does not exceed 70 mm total length and most aspects of its biology are unknown.
Siluriforms are also represented by the family Diplomystidae, which is considered by most ichthyologists to be the most primitive among the Siluriforms and shares characters with primitive teleosts (Lundberg & Baskin 1969;1970;De Pinna 1998).The family is endemic to southern South America and is distributed on both sides of the Andes in rivers and lakes in Chile and Argentina between 34°S and 47°S (Arratia 1983).Three of the six described species are endemic to Chile (Pacific drainages), while the other three are endemic to Argentina (Atlantic drainages), (Muñoz-Ramirez et al, 2010).Species of this genus inhabit well-oxygenated water and move throughout river systems, and thus they are much affected by contamination and construction of dams.Two of the three species present in Chile are found in the Mediter-ranean region.Diplomystes chilensis has a maximum recorded total length of 25 cm.It was originally reported that juveniles inhabit lateral rhithronic zones and adults of more than 12 cm total length move to more potamic flat areas.Feeding is benthonic, changing from aquatic insects in juveniles to Aegla crustaceans in adults.Its reproduction is unknown, but should be very similar to that described for Diplomystes nahuelbutaensis (Vila et al 2006).This species has been classified as endangered, and it has practically disappeared from the region.Diplomystes nahuelbutaensis is morphologically very similar to D. chilensis (Arratia 1987).Some aspects of its biology and habitat were described by Vila et al (1996) and Habit (2005), and its distribution has been discussed by Muñoz-Ramirez et al (2010).It inhabits the rithron of rivers; juveniles pre-Fish fauna in the Chilean Mediterranean region DOI: 10.29094/FiSHMED.2015.002 fer shallow rapids and shallow margins, while adults prefer deeper areas with faster current.Adults reach 30 cm total length (Habit 2005) and the maximum age is 5+ years.Lundberg et al (2004) described freeliving juveniles of 13 mm total length.Food varies from aquatic insects and small mollusks to adult crustaceans Aegla (Arratia 1983b, 1987, Beltrán-Concha et al 2012).Gonads united in an unpaired sac indicate the primitiveness of the family.Reproduction begins in the second year of life in summer-autumn, coinciding with the lowest flows and highest temperatures in the rivers.Eggs are large and demersal (2.5-3.0 mm diameter).Low fecundity, along with slow growth, explains the low population density of the species.As a management measure for the preservation of this species, Habit et al (2002) translocated individuals from deteriorated areas.The last family among siluriforms is Nematogenidae, a monotypic family with a restricted distribution, endemic to Chile.The species Nematogenys inermis is considered to be the most primitive of the Loricariodea (Arratia 1992;de Pinna 1998).As with most Siluriforms, it requires highly oxygenated waters and it has been described as inhabiting fluvial potamic and rithronic areas (Campos et al 1993;Ruiz 1993;Habit & Victoriano 2005).Similar to D. nahuelbutaensis, N. inermis has very large eggs (4-4.5 mm) which mature synchronically, indicating a single spawning (Huaquín et al, 2002;Manríquez et al. 1984).Nematogenys inermis feeds on benthic fauna such as crustaceans, snails, and insects.No more information on the biology of this species is available.Originally indicated as reaching up to 40 cm of total length, it is the largest body size cat fish in Chile.It is currently classified as "Vulnerable" (Table 4), although it has disappeared from the majority of the river systems in its distribution area.Currently only remnant populations in the Coast Range still exist.
Characiforms are represented by the family Characidae.This family of tropical origin is represented in Chile only by the genus Cheirodon, with five native species (Campos 1982); C. pisciculus, C. galusdae (Figure 2), C. austral and C. killiani and one introduced from Argentina (C.interruptus).The species are morphologically similar; however, recently Salas et al (2012) reported morphological landmarks which allow rapid field identification: They are small fish, usually not exceeding 10 cm total length.Their typical habitats are potamal river zones with aquatic vegetation where they feed on the "auwfuchs" community.There is no information available about their reproduction (Campos 1982;Habit et al 2006a).
Galaxiforms are represented by the suborder Osmeroidei, and the families Galaxiidae and Aplochitonidae.Galaxiidae is the most species-rich family of freshwater fish in Chile, comprising over 50 species distributed throughout the Southern Hemisphere (South America, South Africa, Australia and New Zealand; (McDowall 1971(McDowall , 2006)).Eight species belonging to three genera (Galaxias, Brachygalaxias and Aplochiton) are found in Chile, five of which are endemic (Habit et al 2010).Two of the endemics, Brachygalaxias bullocki and B. gothei, the widespread Galaxias maculatus and Aplochiton zebra are present in the Mediterranean zone.Brachygalaxias bullocki and B. gothei are the smallest galaxiids in Chile, found especially abundant in weedy habitats (Eigenmann 1927).Brachygalaxias gothei has very restricted distributions in the Maule River basin (McDowall 1971;Dyer 2000).Brachygalaxias bullocki used to have a larger distribution range, from the Itata River basin to Chiloé Island.However, currently it seems to be extinct in the Biobío and Imperial Rivers (Habit et al 2010), and is a scarce species in the Mediterranean zone.Brachygalaxias bullocki typically inhabits streams and rivers with high levels of humic acids, lowland rivers with native riparian forest and large floodplains.It is found in riverine habitats with little or no current, and is completely absent from rapids or riffles (Habit et al 2010).Galaxias maculatus is generally found close to the coastal zones.It is one of the smallest species of the genus, not exceeding 160 mm total length.Its reproductive period is related to the dynamics of estuaries, since it spawns in coastal zones and juveniles enter the rivers; this process extends from spring to autumn, with temperatures which fluctuate from 6 ºC to 21 ºC, although landlocked lacustrine reproduction has also been reported (Barriga et al 2006).Mature oocytes measure on average 0.9 mm diameter.It feeds on insects, small crustaceans, fish eggs and plankton.In rivers, G. maculatus is found in shallow, slow current zones along river edges, on substrates ranging from mud to boulders, with or without aquatic vegetation.Larger individuals (> 12 cm standard length (SL)) tend to inhabit slightly deeper (> 50 cm) zones (Habit et al 2010).
The family Aplochitonidae is represented by three species in Chile (Aló et al 2013), but only one inhabits the southern zone of the Mediterranean region: Aplochiton zebra.This species has an elongated, flattened body and a small adipose fin.It moves between rivers and lakes, probably for reproduction.In the Chilean Mediterranean zone it only occurs in one lake of the Biobío River basin (Galletué Lake.Campos et al 1993), being more abundant to the south and Patagonia (Habit et al 2010), where it has strong trophic interference from the introduced Salmo trutta (Elgueta et al 2012).
Perciforms are represented by the endemic family Perciliidae with two species, and two species of the family Percichthyidae.The endemic genus Percilia is represented by small darters not exceeding 10 cm total length.Percilia gillissi (Figure 2) is widespread in the Chilean Province (sensu Dyer 2000), found in rithronic and potamal zones of rivers with well-oxygenated water.Its feeding and reproduction are associated with the benthonic fauna (Habit 1998;Aedo et al 2009;Chiang et al 2011b).The other species, P. irwini has a restricted distribution and is considered highly threatened (Habit et al 2009).It can be found in high abundance in riffles and rapids in the middle Biobío River (García et al 2011a) and it has been described as a good swimmer over short distances after (Ruiz 1993).
The genus Percichthys is endemic to South America; the other genera of the family Percichthyidae are found only in Australia (Ruzzante et al 2006).Percichthys trucha occurs both west of the Andes in Pacific drainages and east of the Andes in Atlantic and Pacific drainages, but P. melanops is restricted to western drainages of the Andes (Ruzzante et al 2006).Percichthys trucha is a carnivorous predator beginning at a young age; it may reach 50 cm total length it is found both in fluvial and lacustrine systems.Guerrero (1991) estimated that the species may live for 9 years in Patagonian lakes.It reproduces in spring with demersal eggs.
Percichthys melanops is endemic to the Chilean Province and morphologically similar to P. trucha, although with dark, mottled flanks and smaller size, which usually reaches 30 cm total length.It is found preferentially in river systems of the Coastal Range.Its reproductive period and specific feeding habits are unknown.
Atheriniforms are represented in the region by the family Atherinopsidae.Two genera of this family are found in Chile, Basilichthys without a protractile mouth, which separates it clearly from the other genus, Odontesthes, which has protractile maxillaries (Dyer 2006).Both are widely distributed in the region and associated with a marine origin due to their high salt tolerance.Species of Atherinopsidae have rapid growth and high fecundity (Vila et al 1981b).Basilichthys is a genus of fresh water silversides exclusively distributed in the western slopes of the Andes Range.They have been divided into two groups (Dyer 2006) (Comte & Vila 1987;1992).It reaches a maximum total length of 30 cm at this latitude; in Rapel Reservoir the study of Vila & Soto (1981b) found a three-year age cohort reaching 28 cm total length, but farther south it reaches greater lengths.Spawning begins in spring when water temperature reaches 15 °C and extends during the spring and summer months.Maturation begins at age one year.The absolute fecundity ranges from 2000 to 9000 oocytes in females from 49 to 170 mm of total length.Mature oocytes measure 1.7 to 2.0 mm diameter (Moreno et al 1977).They spawn in clusters that are stuck to riverine macrophytes.It is a benthic feeder, predating on aquatic macroinvertebrates (Bahamondes et al 1979;Montoya et al 2012).
The genus Odontesthes is also represented by two species in the Mediterranean zone of Chile.Odontesthes mauleanum moves extensively among lakes, rivers and estuaries.It has been reported that juveniles and adults in lakes feed mainly on zooplankton.It usually moves up and down rivers feeding on benthic macroinvertebrates (Klink & Eckmann 1985).In Rapel Reservoir it has been reported feeding extensively on small B. microlepidotus and carp (Bahamondes et al 1979).As other Atherinids it has fast growth, reaching 60-100 mm in the first year of life; growth predictions show total length of 30 to 40 cm at eight years; it starts reproducing in the first year of life during spring (Klink & Eckmann 1985).Odontesthes brevianalis is a silverside that inhabits exclusively saline coastal systems where it feeds and reproduces.As most Atherinids it grows rapidly and has been reported to attain up to 40 cm total length at four years.Its food has been reported to be small mollusks and zooplankton.Mature specimens have been found in spring, but detailed information on its re-production is still lacking (Vargas et al 2002).
The freshwater systems of the Mediterranean region of Chile correspond in part to the Chilean Ichthyographic Province (Arratia 1997; Dyer 2000; see Table 2), including river basins from the Huasco to the Biobío Rivers (Fig. 1).The headwaters of these rivers correspond to crenons or high Andean zone, characterized by high current velocity and turbulence, and large-sized substrate (rocks and boulders).The only native fish found there are Siluriforms of the genera Trichomycterus and Diplomystes, which inhabit lateral pools or shallow water with low current velocity.In the middle area or hyporhithron rivers have sequences of rapids and pools, a substrate of rocks and gravel and riparian sectors colonized by macrophytes.In this area, as well as catfish there are Atheriniforms (silversides) and Perciforms (perch); while in the low potamal zone there are also catfish of the genera Nematogenys and Bullockia and Characiforms of the genus Cheirodon.River mouths are inhabited by more salt-tolerant species such as Galaxias maculatus, Odontesthes mauleanum and O. brevianalis.
In the northern Mediterranean zone between 27º and 31º S, near one of the most arid deserts of the world (Atacama Desert), the rivers are separated by up to 1000 km.The Huasco, Choapa, Petorca and Limarí Rivers have low-medium flows (0.24-83.9 m3/s), with one rainy month and a prolonged dry period, with high hydrological fluctuations between years, mainly due to the scarcity of precipitation.The development of these rivers in semi-arid zones does not allow mountain snow melt to increase their flow.Only five fish species are known from these rivers: T. areolatus, C. pisciculus, B. microlepidotus, O. brevianalis and G. maculatus.Farther south in the Mediterranean Region rivers increase their flow; their flows reach above 3000 m3/s, typical of torrential rivers with snow melt runoff (Maule, Itata and Biobío Rivers; Table 1).In these rivers with greater flows additional species are found, typical of the Chilean Ichthyographic Province: D. chilensis, N. inermis, P.
Fish fauna in the Chilean Mediterranean region DOI: 10.29094/FiSHMED.2015.002trucha, P.melanops, P. gillissi and O. mauleanum (Dyer 2000, Vila & Pardo 2008;Habit 1994a;Habit et al 1994b;Habit et al 2006a).The ichthyofauna reaches its maximum diversity at 36º S latitude; with 18 native species in the Biobío River.This is the southernmost river of the Mediterranean Region and that of greatest order and flow; other species in this river are D. nahuelbutaensis, T. chiltoni and B. maldonadoi.

MAIN THREATS AND MANAGEMENT ISSUES
The fish fauna of the Mediterranean watersheds of Chile has a high conservation value because of high endemism and primitiveness, along with their biogeographic relations; Siluriforms with the tropical fauna and the Galaxiidae with Gondwana fauna.Currently 75% of the fish species in the Mediterranean zone of Chile are classified as endangered and vulnerable species (Table 4).According to the literature and the detailed information on the species richness of the most important Mediterranean river basins compiled 40 years ago, their presence and abundance has declined significantly in recent years.This is particularly true for the Aconcagua (Dazarola 1972) and Maipo Rivers (Duarte et al 1971), both located in the more populated areas of the country (cities of Valparaíso and Santiago).For both river systems 10 native species were reported, but currently less than 50% of these can be found.Siluriforms are considered to be in the process of extinction due to their elimination from locations cited in their original descriptions.This is the case of D. chilensis in the Aconcagua basin (Muñoz-Ramirez et al 2010), and of N. inermis in the Biobío basin (Habit et al 2006b).Something similar is occurring with Percichthyidae and Atherinopsidae, mainly in the northern part of their distribution range.In the case of the galaxiids, the latitudinal range of G. maculatus has declined by 26%, and most of this reduction has occurred in the northern part of its range.Brachygalaxias bullocki has experienced reductions (8-17% loss) in the total drainage area occupied, and it has disappeared from, or is now extremely difficult to find, in latitudes 36° to 41° S, coincident with areas of urban growth and intense economic activities (Habit et al 2010).These authors also suggested that negative interactions between introduced and native fish are responsible for some of the range reductions among the Galaxiidae in Chile.
The generalized decrease in the abundances and distribution ranges of the species native to the Mediterranean area of Chile appears to be the synergic result of multiple stressors in the river basins, the most important of which are: 1) the negative effect of introducing as many exotic species as the native species present (Table 5), (Arratia 1981;1997;Basulto 2003;Habit et al 2006b;Vila et al 2006;Habit et al 2010).Recently, Marr et al (2013) reviewed freshwater fish introductions across Mediterranean regions in the world to evaluate the influences of non-native fish on the biogeography of taxonomic and functional diversity, and found that faunal homogenization was greatest in Chile; 2) Changes in soil use in the river basins, mainly replacement of the native forests by pine and Eucalyptus plantations; 3) Extraction of water, with dams in the majority of the rivers; the high water demand has generated negative water balances; together with water extraction for various agricultural crops in the central and southern areas with irrigation channels which in some cases cross drainage systems (e.Fishing; although intensive fishing has not been one of the principal stressors of the native fish fauna as it has been in other areas, mainly due to the small body size of the majority of the species (adults <15 of total length), a few species are caught by recreational and local fishermen such as silversides and perch, and other small fish are used as bait (e.g.catfish).
To all the above must be added natural causes, which probably generate synergic effects with human activities, such as: 1) Lithological characteristics of the area, with significant presence of mineral salts and consequent development of mining; 2) Low growth rates and fecundity of the Siluriforms (e.g.D. nahuelbutaensis, Vila et al 1996); 3) Low genetic variability of some species (Victoriano et al 2012) and their limited swimming capacity (Piedra et al 2012;García et al 2012;Sobenes et al 2013).Another key aspect in the poor conservation state of this fish fauna is that, due to their small size and little use of the native species, these are unknown to the majority of the population and thus there is no social conscience of the need for their protection.In spite of this, in recent years a few management measures have been implemented.

FUTURE DIRECTIONS IN SCIENCE AND MANAGEMENT
Knowledge of the biology and ecology of the fish native to the Mediterranean region of Chile is still incomplete.The information available is mostly classical morphological descriptions, although recently there have been studies of genetics and speciation (Ruzzante et al 2006(Ruzzante et al , 2008;;Unmack et al 2009, 2012, Zemlak et al 2009, 2010;Quezada-Romegialli et al 2010;Véliz et al 2012).We lack specific information about the current distribution and population abundance among river systems, reproductive periods, fecundities and growth rates for the majority of the species.We also need to advance in our understanding of the processes involved in the decrease of their population sizes using ecosystem approaches.There are multiple management needs for the future; the most relevant are the following: 1) it is urgent to implement measures of integrated management of the watersheds, which does not exist formally in Chile, since the productive activities with effects on the aquatic ecosystems are assessed case by case separately; 2) introduce the concept of ecosystem services in water resource management, emphasizing the value of the conservation of biodiversity; 3) generate more information on measures to insure reproduction of the different native species in captivity; 4) continue with the identification of priority conservation sites for native fish fauna and achieve their management.
In summary, we conclude that 75% of the 21 native species of fish present in the Mediterranean river basins of Chile are severely threatened and these threats are not simple, but rather the result of a combination of human activities and natural conditions which are difficult to manage and require more scientific and public attention.

Fis
FIGU g. Habit & Parra 2001); 4) Dredging and channeling of river systems (e.g.Ortiz-Sandoval et al 2009); 5) Construction of diversion or hydropower plants (e.g.Habit et al 2007) which generate changes in the flow regime downstream from the dam (e.g.García et al 2011 b); 6) Entrance of multiple industrial and domestic effluents which generate contamination in the majority of these river basins (Vila et al 2000;.Habit et al 2005, 2006b, Habit & Ortiz 2009; Orrego et al 2009; Chiang et al 2011a, b); and 7)

TABLE 1 .
Minimum and maximum temperatures and flows of main Mediterranean rivers of Chile.Data from the Chilean Dirección General de Agua (DGA) http://snia.dga.cl/BNAConsultas/reportes

TABLE 2 .
Historical distribution of the native fish species in Chile.

fauna in the Chilean Mediterranean region DOI: 10.29094/FiSHMED.2015.002TABLE 3 .
Current presence of native fish species in the main Andean watersheds of the Mediterranean zone of Chile (from north to south).EX-possibly extinct in the watershed; *Diplomystes cf chilensis.

Fish fauna in the Chilean Mediterranean region DOI: 10.29094/FiSHMED.2015.002
, corresponding to B. semotilus and B. microlepidotus, which have disjunct distributions.Basilichthys microlepidotus included two species of the genus with southern distributions, B. microlepidotus from the Huasco River to the Maipo River and B. australis between the Aconcagua River and Chiloé Island.Recently two parallel stud-

TABLE 4 .
Conservation status of the native fish species of the Mediterranean zone of Chile according to the official classification of the Ministerio del Medio Ambiente (http://www.mma.gob.cl/clasificacionespecies/index2.htm).

Fish fauna in the Chilean Mediterranean region DOI: 10.29094/FiSHMED.2015.002
Thus for example currently 30 of the 46 spe-

TABLE 5 .
List of species reported as introduced in continental waters of the Mediterranean zone of Chile.The question mark for Salvelinus namycush indicates that there are no recent records and thus it is not clear if they were successfully established.** Previously described as Cichlassoma facetum for Chile.