Las agregaciones de desove de Tylosurus pacificus (Beloniformes: Belonidae) y su pesca en el Parque Nacional Natural Utría (Pacífico colombiano) / Spawning aggregations of Tylosurus pacificus (Beloniformes: Belonidae) and their fishery in Utría Park, Colombian Pacific

ResumenAlgunas especies de peces marinos tienen complejas relaciones con los ecosistemas costeros durante sus periodos reproductivos, tal es el caso del pez aguja Tylosurus pacificus, que conforma agregaciones de desove en playas de grava en el Parque Nacional Natural Utría. Se describe la actividad pesquera y algunos aspectos de la biología reproductiva de T. pacificus y se proponen algunas medidas para mitigar el impacto sobre este evento y los procesos ecológicos asociados. Se realizó un monitoreo pesquero entre abril 2008 y febrero 2009 en el Parque Nacional Natural Utría (PNNU), Pacífico colombiano. Se analizaron los volúmenes de captura, estructura por talla, proporción de sexos y fecundidad (n= 84). La longitud total osciló entre 60.5 cm y 104 cm con una media y desviación estándar de 85.35 ± 9.09 cm. La fecundidad promedio fue 189 685.56 ovocitos por gónada, con una moda de 8 mm de diámetro y un desarrollo gonadal asincrónico. La especie desova en forma colectiva en la playa cuando la marea alcanza el nivel más alto durante la luna llena y nueva, generalmente al anochecer. Pescadores que habitan los pueblos cercanos aprovechan este recurso, durante la agregación reproductiva de la especie. Es importante ampliar el estudio de la reproducción de T. pacificus y los procesos ecológicos asociados a su desove para poder dar un aprovechamiento adecuado y garantizar la sostenibilidad de su pesquería a largo plazo.

Abstract:Some species of marine fish have complex relationships with coastal ecosystems during their reproductive periods, as the needle fish Tylosurus pacificus that forms spawning aggregations in gravel beaches in Utría Park. We described fishery and some aspects of the reproductive biology of T. pacificus and proposed some strategies to mitigate the impact of this event and associated ecological processes. Fisheries monitoring were conducted between April 2008 and February 2009 in the Utría National Park, Colombian Pacific. Catch volumes, length structure, sex ratio and fecundity (n= 84) were analyzed. The total length ranged among 60.5 and 104 cm with a mean and standard deviation of 85.35 ± 9.09 cm. The average fertility of oocytes per gonad was 189 685.56, with a mode of 8 mm diameter and an asynchronous gonadal development. This species spawns collectively on the beach when the tide reaches the highest level during full and new moon, usually in the evening. Fishermen of a near town take advantage of the spawning aggregation of this species. The reproduction study of T. pacificus and ecological processes associated with their spawning, should be expanded to give adequate use, and ensure the sustainability of their fishery over the long term. Rev. Biol. Trop. 65 (1): 77-87. Epub 2017 March 01.

[Spawning aggregations of Tylosurus pacificus (Beloniformes: Belonidae) and their fishery in Utría Park, Colombian Pacific]. / Las agregaciones de desove de Tylosurus pacificus (Beloniformes: Belonidae) y su pesca en el Parque Nacional Natural Utría (Pacífico colombiano).

Some species of marine fish have complex relationships with coastal ecosystems during their reproductive periods, as the needle fish Tylosurus pacificus that forms spawning aggregations in gravel beaches in Utría Park. We described fishery and some aspects of the reproductive biology of T. pacificus and proposed some strategies to mitigate the impact of this event and associated ecological processes. Fisheries monitoring were conducted between April 2008 and February 2009 in the Utría National Park, Colombian Pacific. Catch volumes, length structure, sex ratio and fecundity (n= 84) were analyzed. The total length ranged among 60.5 and 104 cm with a mean and standard deviation of 85.35 ± 9.09 cm. The average fertility of oocytes per gonad was 189 685.56, with a mode of 8 mm diameter and an asynchronous gonadal development. This species spawns collectively on the beach when the tide reaches the highest level during full and new moon, usually in the evening. Fishermen of a near town take advantage of the spawning aggregation of this species. The reproduction study of T. pacificus and ecological processes associated with their spawning, should be expanded to give adequate use, and ensure the sustainability of their fishery over the long term.

Variation in freshwater fish assemblages along a regional elevation gradient in the northern Andes, Colombia.

Studies on elevation diversity gradients have covered a large number of taxa and regions throughout the world; however, studies of freshwater fish are scarce and restricted to examining their changes along a specific gradient. These studies have reported a monotonic decrease in species richness with increasing elevation, but ignore the high taxonomic differentiation of each headwater assemblage that may generate high ß-diversity among them. Here, we analyzed how fish assemblages vary with elevation among regional elevation bands, and how these changes are related to four environmental clines and to changes in the distribution, habitat use, and the morphology of fish species. Using a standardized field sampling technique, we assessed three different diversity and two structural assemblage measures across six regional elevation bands located in the northern Andes (Colombia). Each species was assigned to a functional group based on its body shape, habitat use, morphological, and/or behavioral adaptations. Additionally, at each sampling site, we measured four environmental variables. Our analyses showed: (1) After a monotonic decrease in species richness, we detected an increase in richness in the upper part of the gradient; (2) diversity patterns vary depending on the diversity measure used; (3) diversity patterns can be attributed to changes in species distribution and in the richness and proportions of functional groups along the regional elevation gradient; and (4) diversity patterns and changes in functional groups are highly correlated with variations in environmental variables, which also vary with elevation. These results suggest a novel pattern of variation in species richness with elevation: Species richness increases at the headwaters of the northern Andes owing to the cumulative number of endemic species there. This highlights the need for large-scale studies and has important implications for the aquatic conservation of the region.

Gorgona, Baudó y Darién (Chocó Biogeográfico, Colombia): ecorregiones modelo para los estudios ecológicos de comunidades de quebradas costeras / Gorgona, Baudó and Darién (Biogeographic Chocó, Colombia): model ecoregions for coastal stream ecology studies

This paper summarizes the available information on the geology, hydrology, and biota of coastal streams located in the Gorgona National Natural Park (GNNP), and the Baudó and Darién ecoregions within the Biogeographic Chocó (Colombia). Despite of the scant number of studies, we hypothesized that these streams are consistent with the typology observed in volcanic oceanic islands in the Caribbean and the Pacific that do not conform to the tenets of the River Continuum Concept. Coastal streams in the Biogeographic Chocó are short (10(0)-10¹km) and steep and waterfalls and cascades are frequent due to tectonic origin. Step-and-pool sequences are common in montane reaches, while cobble-bed glides and riffles dominate in coastal plain reaches. Flow regimes are flashy in Pacific drainages (annual rainfall: <7000mm), but seasonally dry in the Caribbean drainages (<3500mm). Therefore, floods and droughts are important drivers of communities and ecosystem processes. Canopies are closed in low-order streams discharging directly to the ocean, thus contributing large amounts of litter. Diadromous fish and shrimp dominate consumer assemblages and various species are shared with streams in the Central America and the Antilles. These species play ecological roles probably equivalent to those found in other regions. These coastal streams are unique in terms of the number of primary freshwater fishes found (some endemics), and the functionally absence of diadromous gastropods. Rev. Biol. Trop. 62 (Suppl. 1): 43-64. Epub 2014 February 01.

A pesar de la escasez de estudios sobre la geología, hidrología y biota de las quebradas costeras ubicadas en el Chocó Biogeográfico, se hipotetiza que éstas se ajustan a la tipología observada en las islas oceánicas volcánicas del Caribe y el Pacífico, las cuales no cumplen con las predicciones del Concepto del Río Continuo. Estas quebradas son cortas (<10¹km) y muy pendientes debido a su origen tectónico, y presentan lechos dominados por bloques y cantos rodados. El régimen de caudal es torrencial en la vertiente Pacífico, pero estacionalmente seco en la vertiente Caribe. Los doseles cerrados aportan grandes cantidades de hojarasca a las quebradas que desembocan al mar con bajo orden. Las especies diádromas, con afinidades centroamericanas y antillanas, dominan los ensamblajes y posiblemente cumplen papeles ecológicos equivalentes a los establecidos en otras regiones. Particularmente, las quebradas costeras de esta provincia presentan varias especies de peces dulceacuícolas primarios, algunas endémicas, y carecen de gasterópodos. Los procesos geomorfológicos e hidrológicos de las cabeceras influyen sobre la dinámica ecosistémica de estas quebradas. Se proponen cinco hipótesis sobre la estructura y composición comunitaria. Se advierte que el PNNG es un modelo útil para la ecología lótica costera, pero que tiene particularidades.