This study reports seasonal variation, growth parameters and natural mortality for Eucinostomus gula and Eucinostomus argenteus inhabiting La Carbonera, a tropical coastal lagoon on the northwestern coast of theYucatan Peninsula, Mexico. Specimens were collected between April 2009 and March 2010. A total of 2700organisms of E. gula (> 80% in rainy season ) and 1577 organisms of E. argenteus (>50% in dry season)were collected during the study period. Length-weight relationship (LWR) obtained was W = 8.323E-03Lt2.92 in E. argenteus and W = 7.314E-03 Lt2.92 in E. gula. Growth parameters of von Bertalanffy growthfunction (VBGF) by length frequency analysis were in E. argenteus: L∞ = 13.65 cm, k = 0.54 year-1 and t0= - 0.37 years; and in E. gula: L∞ = 12.60 cm, k = 0.68 year-1 and t0 = - 0.28 years. Additionally, estimatednatural mortality in E. gula was 1.50 year-1 and in E. argenteus was 1.9 year-1. This study presents the firstestimation for both species of model parameters, growth performance index and mortality for the Yucatan Peninsula, which is relevant for the proper implementation of conservation measures for E. gula and E. argenteus in an important coastal zone of the Yucatan Peninsula.Se reportan la variación temporal, los parámetros de crecimiento y la mortalidad natural para Eucinostomus gula y Eucinostomus argenteus que habitan en la laguna costera tropical La Carbonera, al noroeste de la península de Yucatán, México. Los especímenes fueron recolectados entre abril de 2009 a marzo de 2010. Un total de 2 700 organismos de E. gula (> 80% en la estación lluviosa) y 1 577 organismos de E. argenteus (> 50% en la estación seca) fueron recolectados durante el período de estudio. Se determinó la relación peso-longitud (RPL) como: P = 8.323E-03 Lt 2.92 en E. argenteus y P = 7.314E-03 Lt2.92 en E. gula. Para E. argenteus, los parámetros de crecimiento de la ecuación de crecimiento de von Bertalanffy (ECVB) fueron: L∞ = 13.65 cm, k = 0.54 año-1 y t0 = - 0.37 años; mientras que para E. gula fueron: L∞ = 12.60 cm, k = 0.68 año-1 y t0 = - 0.28 años. La mortalidad natural en E. gula fue 1.50 año-1 y en E. argenteus fue 1.9 año-1. Este estudio presenta la primera estimación para ambas especies de los modelos de crecimiento, el índice del desempeño de crecimiento y la mortalidad natural para la península de Yucatán, lo que es relevante para la adecuada implementación de medidas de conservación de E. gula y E. argenteus en una valiosa zona costera de la península de Yucatán.
Summary
This study reports length‐weight relationships and growth parameters for Floridichthys polyommus Hubbs, 1936 and Fundulus persimilis Miller, 1955 from La Carbonera, a karstic tropical coastal lagoon on the northwestern coast of the Yucatan Peninsula, Mexico. Specimens were collected between April 2009 and March 2010. The resulting length‐weight relationship for F. polyommus was: W = 0.0180 Lt3.37 and W = 0.0142 Lt3.35 for F. persimilis. This study presents the first estimation for both species of the von Bertalanffy growth model parameters, the growth performance index, the L50, and is the first report of the length‐weight relationship for F. persimilis.
Although the Gulf toadfish, Opsanus beta, is an abundant member of the nearshore Gulf of Mexico ichthyofaunal assemblage, little information exists regarding the ecology of the species, especially for southern Gulf of Mexico populations. We added to the existing knowledge of this species by describing the reproductive structures and examining the early life history of this species in the Tecolutla estuary, Mexico. Macro-and microscopic examination of 7 males showed spermatogenesis to be similar to other teleost species except for the occurrence of biflagellate spermatozoa. Histological examination of the male accessory gland showed 3 tissue layers, but their functions are still undetermined. We found asynchronous development of oocytes in the ovaries of 16 females, which may indicate multiple spawning over the long spawning season noted in this study. Batch fecundity estimates among females ranged from 79 to 518 mature ova with a mean ovum diameter of 3.5 mm. The above-mentioned factors along with large size at hatching, attached larval forms, and paternal care may account, in part, for the abundance of this species in highly dynamic systems. RESUMEN Aunque el pez sapo del Golfo, Opsanus beta, es un miembro abundante del ensamble ictiofaunístico de las costas del Golfo de México, existe poca información acerca de la ecología de la especie, especialmente para las poblaciones del sureste del Golfo de México. Nosotros contribuimos al conocimiento existente de esta especie, describiendo las estructuras reproductoras y examinando las etapas tempranas del ciclo de vida de esta especie en el estuario de Tecolutla, México. El examen macro y microscópico de 7 individuos machos mostraron espermatogénesis similar al de otras especies de teleósteos, excepto por la presencia de espermatozoides biflagelados. El examen histológico de las glándulas accesorias del macho mostró una composición de tres capas de tejido, pero su función es aun indeterminada. Encontramos desarrollo asincrónico de los ovocitos de 16 hembras examinadas, que pueden indicar desoves múltiples a lo largo de la temporada de desove. La estimación de la fecundidad en las hembras examinadas presentó un intervalo de 79 a 518 huevos maduros con un diámetro de 3.5 mm. Los factores anteriores, junto con la talla grande al eclosionar, las formas larvales adheridas y el cuidado paterno, pueden responder a la abundancia de esta especie en sistemas muy dinámicos.
Summary
This study reports length–weight relationships and growth parameters for Chriodorus atherinoides from La Carbonera, a karstic tropical coastal lagoon on the northwestern coast of the Yucatan Peninsula, Mexico. A total of 667 specimens were collected between April 2009 and March 2010. The length‐weight relationship obtained was W = 0.0034Lt3.22. This study presents the first estimation of the model parameters of the von Bertalanffy growth equation (L∞ = 27.30 cm, k = 0.76 year−1 and t0 = −0.178 years), the instantaneous total mortality (2.51 year−1) and the maximum length record (26.0 cm total length), which is greater than previously recorded.
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