Gorgonio Ruiz-Campos

FRESHWATER SHRIMP OF THE GENUS MACROBRACHIUM (DECAPODA: PALAEMONIDAE) FROM THE BAJA CALIFORNIA PENINSULA, MÉXICO

Abstract Freshwater decapods like the palaemonid river shrimp have received little attention in the Baja California Peninsula, México. From the first formal report in 1878 to now, only three Macrobrachium species have been reported (M. americanum, M. digueti, and M. tenellum) from the peninsula in only three basins. We made a taxonomic study of freshwater shrimp, which included an extensive field survey at 81 sites distributed on both the Pacific and the Gulf of California slopes and a revision of material from the area that had been deposited in scientific collections. We report six species of Macrobrachium by adding M. hobbsi, M. michoacanus, and M. olfersii. We also discuss some aspects of the diversity and conservation of these species in the peninsula and provide an identification key for the Macrobrachium shrimp of northwestern México.

An annotated distributional checklist of the freshwater fish from Baja California Sur, México

An annotated distributional checklist of thefreshwater fish recorded historically andrecently in Baja California Sur, México, isprovided. This checklist is supported with4,857 specimens collected at freshwaterlocalities during the period of May 1991 toApril 2002, and complemented with a review ofspecimens in museums and in the literature. Thenative ichthyofauna is represented by 19species belonging to 16 genera and 12 families,with only two cases of endemism (Funduluslima and Gobiesox juniperoserrai). Thefirst occurrence of Centropomus viridisin freshwater environments of Baja Californiapeninsula is reported here. The familiesEleotridae and Mugilidae are the most diversewith 3 species each. Zoogeographically, most ofthe species are of tropical affinity(panamanian 63%, tropical amphiamerican 16%and circumtropical 5%) and of marineecological derivation (sporadic 53%,complementary 26%, vicarious 16% anddiadromous 5%). Six species are exotic in thisregion, of which Cyprinus carpio, Xiphophorus helleri and Tilapia cf. zilli are of recent introduction. The currentstatus of the endemic killifish (Funduluslima) is determined as endangered due tocompetition with Tilapia cf. zilliand other exotic fish.An annotated distributional checklist of thefreshwater fish recorded historically andrecently in Baja California Sur, Mexico, isprovided. This checklist is supported with4,857 specimens collected at freshwaterlocalities during the period of May 1991 toApril 2002, and complemented with a review ofspecimens in museums and in the literature. Thenative ichthyofauna is represented by 19species belonging to 16 genera and 12 families,with only two cases of endemism (Funduluslima and Gobiesox juniperoserrai). Thefirst occurrence of Centropomus viridisin freshwater environments of Baja Californiapeninsula is reported here. The familiesEleotridae and Mugilidae are the most diversewith 3 species each. Zoogeographically, most ofthe species are of tropical affinity(panamanian 63%, tropical amphiamerican 16%and circumtropical 5%) and of marineecological derivation (sporadic 53%,complementary 26%, vicarious 16% anddiadromous 5%). Six species are exotic in thisregion, of which Cyprinus carpio, Xiphophorus helleri and Tilapia cf. zilli are of recent introduction. The currentstatus of the endemic killifish (Funduluslima) is determined as endangered due tocompetition with Tilapia cf. zilliand other exotic fish.

Mitochondrial haplotype variation in wild trout populations (Teleostei: Salmonidae) from northwestern Mexico

The variation and composition of Mexican wild trout mitochondrial DNA haplotypes throughout northwestern Mexico was determined by means of polymerase chain reaction–restriction fragment polymorphism analysis (PCR–RFLP), of one region of mitochondrial DNA between cytochrome b and the D-loop. This analysis was based on 261 specimens taken in 12 basins and four hatcheries from northwestern Mexico. From 23 haplotypes, 15 wild trout haplotypes were identified and classified in four groups: (1) one restricted to Nelson’s trout (Oncorhynchus mykiss nelsoni), (2) four restricted to Río Mayo and RíoYaqui trout (O. mykiss sspp.), (3) six to Mexican golden trout (O. chrysogaster) with two subgroups, and (4) one exclusive to Río Piaxtla trout. Distributions of native haplotypes broadly overlap the distribution of non-native hatchery rainbow trout reflecting the historical management of introductions of exotic rainbow trout and the artificial transference of these trout among basins.

DISTRIBUTION AND ABUNDANCE OF THE ENDANGERED KILLIFISH FUNDULUS LIMA, AND ITS INTERACTION WITH EXOTIC FISHES IN OASES OF CENTRAL BAJA CALIFORNIA, MEXICO

Abstract The distribution and abundance of the endangered Baja California killifish, Fundulus lima, and its interaction with exotic fishes were studied in oases of the central part of Baja California peninsula, Mexico (Río San Ignacio and Río La Purísima basins), from October 2002 to July 2004. Five fish species were recorded: the native killifish and 4 exotics (Cyprinus carpio, Poecilia reticulata, Xiphophorus hellerii, and Tilapia cf. zillii). Two new populations of the killifish are reported for the Río San Ignacio as well as confirmation of occurrence in the upper Río La Purísima. Density of the killifish in the Río San Ignacio showed a significant inverse correlation with that of the exotic redbelly tilapia (Tilapia cf. zillii). Baja California killifish densities in both rivers decreased significantly after the hurricane-induced flood event of 23 September 2003, but exhibited notable recovery 10 months later. Relative abundance of killifish at the type locality, San Ignacio oasis, decreased significantly during an 8-year period after introduction of tilapia. The status of Baja California killifish should be changed from threatened to endangered to reflect continued reductions in distribution as result of proliferation of nonnative fishes, particularly redbelly tilapia. Management efforts to reduce abundance of exotic fishes are needed to ensure persistence of the endemic Baja California killifish.

Population genetic structure and ancestry of steelhead/rainbow trout (Oncorhynchus mykiss) at the extreme southern edge of their range in North America

Steelhead (Oncorhynchus mykiss) populations have declined dramatically in many parts of their range in North America, most critically in Southern California, where these anadromous trout are now classified as ‘Endangered’ under the United States Endangered Species Act. The widespread introduction of hatchery rainbow trout, the domesticated freshwater resident form of the species O. mykiss, is one factor threatening the long-term persistence of native steelhead and other trout populations. To identify where native fish of coastal steelhead lineage remained, we performed a population genetic analysis of microsatellite and SNP genotypes from O. mykiss populations at the extreme southern end of their range in Southern California, USA and Baja California, Mexico. In the northern part of this region, nearly all populations appeared to be primarily descendants of native coastal steelhead. However, in the southern, more urbanized part of this region, the majority of the sampled populations were derived primarily from hatchery trout, indicating either complete replacement of native fish or a strong signal of introgression overlaying native ancestry. Nevertheless, these genetically introgressed populations represent potentially critical genetic resources for the continued persistence of viable networks of O. mykiss populations, given the limited native ancestry uncovered in this region and the importance of genetic variation in adaptation. This study elucidates the geographic distribution of native trout populations in this region, and serves as a baseline for evaluating the impacts of hatchery trout on native O. mykiss populations and the success of steelhead conservation and recovery efforts.

Threatened Fishes of the World: Fundulus lima Vaillant, 1894 (Fundulidae)

Common names: Baja killifish, San Ignacio killifish (E), Sardinita peninsular (S). Conservation status: Threatened, according to SEDESOL (1994) on the basis of its confined distribution and low abundance. Identification: Dorsal and anal fins with 12 rays, eye diameter 4.5 in head, mouth size 4.1 in head, scales in lateral series 34–38 (mean= 36), and breeding males with ctenii of lateral scales strongly developed (Myers 1930); allozymic analysis has identified three diagnostic loci Pgm100, Pt-2102, and Aat-2102 (Camarena-Rosales et al. 1999). Photograph by Gorgonio RuizCampos from Arroyo (Oasis) La Purisima (Carambuche), March 1998, breeding male (total length 82.2 mm). Distribution: Type locality is oasis of San Ignacio, Baja California Sur, Mexico (Vaillant 1894, Myers 1930). Endemic to the oases of the Pacific drainage of Baja California Sur, Mexico, from San Ignacio (Myers 1930, Follett 1960) to Arroyo Las Pocitas (G. Ruiz-Campos unpublished data). The author and collaborators have collected (period of 1991–1998) this species in the following localities: San Ignacio (San Ignacio), La Purisima (Carambuche), Bramonas (Bebelamas, San Luis Gonzaga and Las Cuedas), San Pedro (San Pedro de La Presa, San Basilio, Merecuaco, Pozo del Iritu), and Las Pocitas (El Caracol). Abundance: Although there are no quantitative evaluations of the abundance of F. lima before the introduction of exotic fishes to the oases (e.g., Cyprinus carpio, Poecilia reticulata, Xiphophorus helleri, X. maculatus, and Tilapia cf. zilli), current monitoring (1991–1998) along its historic range has revealed low relative abundance (0–5%) of this native killifish as compared to exotic species, mainly T. cf. zilli and P. reticulata (G. Ruiz-Campos unpublished data). The least decimated population of F. lima was detected in the locality of Las Cuedas (Bramonas basin). Habitat and ecology: The oases that this species inhabits register low salinities (0.3–1.0 ppt), and their bottoms are formed of bedrock with sandy/gravel patches. Aquatic macrophytes are represented by Chara sp. and Potamogeton sp. (Espinosa Perez & Castro-Aguirre 1996). San Ignacio killifish prefer pool habitats with lateral scour (0.3–2.0 m deep) and temperatures ranging between 20 and 28◦C (G. Ruiz-Campos unpublished data). This freshwater killifish is similar to other relatives obtaining food by browsing peryphyton of mainly filamentous green algae and diatoms, and associated ostracods and cladocerans (Alaniz-Garcia 1995). Reproduction: No studies on breeding aspects of this fundulid species have been made; however, observation of males with nuptial coloration and strongly developed ctenii from March to April suggests reproduction during this time (G. Ruiz-Campos unpublished data). Threats: Since this killifish is one of only three known freshwater taxa endemic to Baja California peninsula, its very limited distribution merits considetarion at least as threatened. Recent distribution evaluations (1991–1999) along its historic range and adjacent areas indicate significant reductions of populations in most of localities due to competitive exclusion by exotic cichlid T. cf. zilli (G. Ruiz-Campos unpublished data). Stocking of exotic fishes (mainly Tilapia spp. and Cyprinus carpio) in the oases dates from 1976 as part of a federal program to promote rural aquaculture, with the harmful results mentioned above. Conservation recommendation: Although eradication of Tilapia spp. and other exotic fishes from the oases is unrealistic, because of the size and distance among them; the transplanting of F. lima to pristine oases inside its native range (Hendrickson & Brooks 1991) might be an appropriate strategy to recover this endemic taxon. Remarks: Based on allozymic studies, F. lima is closely related to F. parvipinnis brevis (Camarena-Rosales et al. 1999), a coastal subspecies endemic to Bahia Magdalena, Baja California Sur (Osburn & Nichols 1916). Myers’ (1930) original suggestion that F. lima is a landlocked derivative of F. parvipinnis was supported by Miller (1943) and very recently by Camarena-Rosales et al. (1999).

Effects of Exotic Fishes on the Somatic Condition of the Endangered Killifish Fundulus lima (Teleostei: Fundulidae) in Oases of Baja California Sur, Mexico

Abstract We assessed the effects of the abundance and biomass of four exotic fishes (common carp, Cyprinus carpio; guppy, Poecilia reticulata; green swordtail, Xiphophorus hellerii; and redbelly tilapia, Tilapia cf. zillii) on the residual somatic condition (Kr) of endangered Baja California killifish (Fundulus lima) in two oasis systems of Baja California Sur, Mexico. We used multiple regressions to analyze relationships between Kr of the killifish and 21 ecological variables. Biomass of redbelly tilapia and common carp were variables that better explained variation in Kr among populations of killifish. In both drainages, redbelly tilapia was the dominant fish, which relegated smaller habitat units to the other coexisting species of fishes, increasing competition among them and decreasing Kr and abundance of the endemic killifish. We concluded that Kr for populations of killifish may be a good indicator of the competitive interactions with exotic fishes in drainages of Baja California peninsula and should be considered when such stocks are subject to recovery plans or any other management program. Resumen Evaluamos los efectos de la abundancia y biomasa de cuatro especies ícticas exóticas (carpa común, Cyprinus carpio; gupi, Poecilia reticulata; espadita verde, Xiphophorus hellerii; y la tilapia panza roja, Tilapia cf. zillii) sobre la condición somática residual (Kr) de la sardinilla peninsular en peligro de extinción (Fundulus lima) en dos sistemas de oasis de Baja California Sur, México. Utilizamos regresiones múltiples para analizar las relaciones entre el Kr de la sardinilla peninsular y 21 variables ecológicas, siendo las biomasas de la tilapia panza roja y la carpa común las variables que mejor explicaron la variación de Kr para las poblaciones de sardinilla peninsular. La tilapia panza roja fue la especie dominante en ambas cuencas, relegando a las otras especies ícticas coexistentes a ocupar unidades de hábitat más pequeñas, incrementando una mayor competencia entre ellas y reduciendo el Kr y la abundancia de la sardinilla peninsular. Concluimos que el Kr de las poblaciones de sardinilla peninsular puede ser un buen indicador de las interacciones competitivas con especies exóticas en las cuencas hidrológicas de la península de Baja California y podría ser considerado cuando tales poblaciones estén sujetas a planes de recuperación o cualquier otro programa de manejo.

Population morphometric variation of the endemic freshwater killifish, Fundulus lima (Teleostei: Fundulidae), and its coastal relative F. parvipinnis from the Baja California Peninsula, Mexico

The population morphometric variation of the endangered freshwater killifish (Fundulus lima) was evaluated and compared with that of its euryhaline coastal relatives (F. parvipinnis parvipinnis and F. p. brevis) on the basis of 384 specimens from the Baja California peninsula, Mexico. Forty five standardized body distances were compared by means of discriminant function analysis (DFA). Sixteen body distances were significant to distinguish two groups of populations for F. lima: a first group represented by the Bebelamas and San Javier basins, and second group composed by the basins of San Ignacio, La Purísima, San Luis, San Pedro and Las Pocitas. When all freshwater and coastal populations were compared, the southernmost population of F. lima (Las Pocitas) showed a higher morphometric similarity with the southern coastal subspecies (F. p. brevis), while another southern population (San Pedro) had an intermediate position between the freshwater and coastal forms. This study suggests the presence of five evolutionary units (three freshwater and two coastal) for the genus Fundulus in the Baja California peninsula.

Biometric and Allozymic Characterization of Three Coastal and Inland Killifish Populations (Pisces: Fundulidae) from the Peninsula of Baja California, Mexico

Type localities and/or central populations of coastal and inland killifishes along the peninsula of Baja California were sampled to survey the biometric and allozymic relationships among them. The standard stepwise discriminatory function analysis of biometric characters classified organisms into three well distinctive groups (p < 0.001 ). The number of scales in the lateral series successfully split the species, while the caudal length/standard length ratio did so between subspecies. Two diagnostic loci (PROT-2 * and AAT-2 * ) segregated private alleles in each taxon. Fundulus lima showed lower genetic variability levels than F. parvipinnis spp., in both polymorphism (18.8% in F. lima vs. 25.0% in F. parvipinnis spp.) and expected heterozygosity (0.060 in F. lima vs 0.099 in F. p. brevis and 0.089 in F. p. parvipinnis). The reduced genetic variability in the threatened species F. lima may be related to its evolutionary history. Neis genetic distance between F. lima and F. p. parvipinnis was 0.247, while 0.075 between F. parvipinnis spp.

Notas ecologicas sobre la avifauna de Laguna el Rosario, Baja California, Mexico

regi6n antes aludida (e.g., Grinnell, 1928; Wilbur, 1987). Grinnell (1928), en su estudio compilativo de la ornitofauna de la peninsula de Baja California, ubica alrededor de 48 especies registradas para El Rosario y sus inmediaciones (Nelson, 1921); sin embargo, la mayoria de s asimismo se hacen anotaciones sobre el tipo de habitat donde se distribuyen las especies. Todo ello, con la finalidad de dar las bases necesarias para la proposici6n y desarrollo de futuros programas sobre el manejo y conservaci6n del recurso aviar, y de sus habitats.