ABSTRACT
Variability in the relative abundance, size structure and sex ratio of the dolphinfish Coryphaena hippurus (Pisces: Coryphaenidae) in the Gulf of Tehuantepec, México. The dolphinfish (Coryphaena hippurus), is an oceanic epipelagic fish found worldwide in tropical and subtropical waters, with a high dispersal capability via large-scale migrations. This fast-swimming top-level predator is abundant in the Gulf of Tehuantepec, where it is caught incidentally by artisanal fisheries, and represents a target species for both recreational and commercial fisheries in Mexico, Ecuador, Peru and Central America. Nowadays, local fishery information on this species is scarce, thus our objective was to analyze the size structure by sex and the catch-per-unit-effort (CPUE) tendency of dolphinfish caught in the Gulf of Tehuantepec, from 2000 to 2007. For this, fishery catches information was obtained from the artisanal fleet, at six landing sites in the Gulf, and the sex ratio, fork length (FL) and the catch per unit effort (CPUE) were estimated. From all sampling sites, a total of 3 494 females, and 3 877 males were obtained, and dolphinfish size as fork length (FL) ranged from 20.5 to 152cm. Fish size ranged from 25.5 to 148cm furcal length (FL) in males, and 20.5 to 129cm FL in females. The sex ratio (males:females) was 1:1, except in April-May (1:1.5, p < 0.05) and November (1:0.5, p < 0.05). The sex ratio at different size classes showed a significant bias towards females at smaller sizes (< 75cm FL), whereas the males were predominant in larger size classes (> 100cm FL). The size structure was bimodal, with a variation in the size average; the modes were defined as the small group (FL = 50-55cm) and the large size group (FL = 100-110cm). The CPUE showed seasonal changes: values were high for the November-December period, and values were lower for July-August. The seasonal and inter annual variation in the abundance of dolphinfish is probably related to a pre-spawning migration in close relation to the rain-drought regime characteristic of the region, and the associated wind upwelling season of "Tehuanos" in the Gulf of Tehuantepec.
Subject(s)
Perciformes/anatomy & histology , Perciformes/classification , Animals , Female , Male , Mexico , Population Density , Seasons , Sex RatioABSTRACT
The dolphinfish (Coryphaena hippurus), is an oceanic epipelagic fish found worldwide in tropical and subtropical waters, with a high dispersal capability via large-scale migrations. This fast-swimming top-level predator is abundant in the Gulf of Tehuantepec, where it is caught incidentally by artisanal fisheries, and represents a target species for both recreational and commercial fisheries in Mexico, Ecuador, Peru and Central America. Nowadays, local fishery information on this species is scarce, thus our objective was to analyze the size structure by sex and the catch-per-unit-effort (CPUE) tendency of dolphinfish caught in the Gulf of Tehuantepec, from 2000 to 2007. For this, fishery catches information was obtained from the artisanal fleet, at six landing sites in the Gulf, and the sex ratio, fork length (FL) and the catch per unit effort (CPUE) were estimated. From all sampling sites, a total of 3 494 females, and 3 877 males were obtained, and dolphinfish size as fork length (FL) ranged from 20.5 to 152cm. Fish size ranged from 25.5 to 148cm furcal length (FL) in males, and 20.5 to 129cm FL in females. The sex ratio (males:females) was 1:1, except in April-May (1:1.5, p<0.05) and November (1:0.5, p<0.05). The sex ratio at different size classes showed a significant bias towards females at smaller sizes (<75cm FL), whereas the males were predominant in larger size classes (>100cm FL). The size structure was bimodal, with a variation in the size average; the modes were defined as the small group (FL=50-55cm) and the large size group (FL=100-110cm). The CPUE showed seasonal changes: values were high for the November-December period, and values were lower for July-August. The seasonal and inter annual variation in the abundance of dolphinfish is probably related to a pre-spawning migration in close relation to the rain-drought regime characteristic of the region, and the associated wind upwelling season of Tehuanos in the Gulf of Tehuantepec. Rev. Biol. Trop. 62 (2): 611-626. Epub 2014 June 01.
El dorado Coryphaena hippurus es un depredador oceánico epipelágico que se distribuye en aguas tropicales y subtropicales de todos los océanos. Son peces con alta capacidad de dispersión por su migración a gran escala. El Golfo de Tehuantepec es una de las áreas de mayor abundancia de C. hippurus, donde se registran capturas incidentales en la pesca artesanal y sostiene pesquerías recreacionales y comerciales de pequeña escala en México, Ecuador, Perú y Centroamérica. Aquí se analizan los cambios inter-anuales en la estructura de tallas por sexo del dorado durante 2000-2007, así como la tendencia de la captura por unidad de esfuerzo (CPUE) de dorado efectuada por la flota ribereña. Los resultados están basados en 3 494 hembras y 3 877 machos capturados por pesca artesanal en 6 localidades del Pacífico Sur provenientes de muestreos mensuales. Se estimó la CPUE a partir del número de organismos capturados por viaje de pesca. Los machos pre- sentaron tallas entre 25.5 a 148cm de longitud furcal (Lf), mientras que en hembras las tallas registradas fueron de 20.5 a 129cm Lf. La proporción de sexos mostró patrones estacionales a lo largo del año y diferencias con respecto de Lf, a tallas pequeñas predominaron las hembras (<75cm FL) y a tallas grandes los machos (>100cm Lf). La estructura de Lf mostró una tendencia bimodal, con una variación en la Lf promedio de 2000 a 2007; las modas estuvieron definidas como el grupo de tamaño pequeño (Lf=50-55cm) y el grupo de tamaño grande (Lf=100 a 110cm). La CPUE tuvo cambios estacionales: los periodos más altos se registraron en noviembre-diciembre y mayo; los más bajos en julio-agosto. La variación estacional e interanual en la abundancia del dorado probablemente se encuentre relacionada con una migración pre desove, en estrecha relación con el régimen lluvias-estiaje característico de la región, y la temporada de surgencias eólicas asociadas a la temporada de Tehuanos en el Golfo de Tehuantepec.
Subject(s)
Animals , Female , Male , Perciformes/anatomy & histology , Perciformes/classification , Mexico , Population Density , Seasons , Sex RatioABSTRACT
Reproductive cycle of the mollusk Atrina maura (Pterioidea: Pinnidae) in a coastal lagoon system of the Mexican South Pacific. From February 1997 to February 1998, random samples of the mollusk Atrina maura were collected on a monthly basis from the Corralero-Alotengo lagoon system, Oaxaca, Mexico. The soft parts were separated from the valve, washed in situ, and placed in a Davison solution. The gonadosomatic index (GSI) and the muscle yield index (MYI) were measured, and the reproductive cycle was characterized by histological cuts. A. maura has two important reproductive periods, one from April to July and another from October to November; there is a resting period from August to September. The reproductive cycle has a direct relationship with the GSI and a reverse relationship with the MYI. There was evidence of a close relationship of the spawning and post-spawning periods with the water temperature (R = 0.991, p = 0.002). Females dominate numerically throughout the year, but the difference is significant (X²: p= 0.05) only in November. Rev. Biol. Trop. 55 (3-4): 839-852. Epub 2007 December, 28.
De febrero de 1997 a febrero de 1998, se recolectaron mensualmente muestras aleatorias del molusco Atrina maura en el sistema lagunar Corralero-Alotengo, Oaxaca, México. Se extrajeron las partes blandas para lavarlas in situ y fijarlas en solución Davison. En el laboratorio se pesaron para obtener los índices gonadosomático (IGS) y de rendimiento muscular (IRM), y mediante cortes histológico de las gónadas se caracterizó el ciclo reproductivo. Esta población se reproduce casi todo el año, con dos periodos reproductivos importantes: uno de abril a julio y otro de octubre a noviembre, y una sola época de reposo, en agosto y septiembre. El ciclo reproductivo tiene una relación directa con el IGS e inversa con el IRM. Hay evidencias de una relación estrecha de las época de desove y postdesove con la temperatura del agua (R = 0.991, p 
0.002). Las hembras predominaron casi todo el año, aunque esta proporción solo tuvo diferencias estadísticamente significativas en noviembre (X²: p= 0.05).
Subject(s)
Animals , Female , Male , Bivalvia/physiology , Gonads/growth & development , Sexual Maturation/physiology , Mexico , Reproduction/physiology , SeasonsABSTRACT
From February 1997 to February 1998, random samples of the mollusk Atrina maura were collected on a monthly basis from the Corralero-Alotengo lagoon system, Oaxaca, Mexico. The soft parts were separated from the valve, washed in situ, and placed in a Davison solution. The gonadosomatic index (GSI) and the muscle yield index (MYI) were measured, and the reproductive cycle was characterized by histological cuts. A. maura has two important reproductive periods, one from April to July and another from October to November; there is a resting period from August to September. The reproductive cycle has a direct relationship with the GSI and a reverse relationship with the MYI. There was evidence of a close relationship of the spawning and post-spawning periods with the water temperature (R = 0.991, p > 0.002). Females dominate numerically throughout the year, but the difference is significant (chi2: p > or = 0.05) only in November.