RESUMO
This study aimed to describe updated information on the basic reproductive biology of Sphoeroides annulatus females and potential use of the gonadosomatic index I G as input data to assess length at 50% maturity ( L 50 ) and identify the breeding season. From April 2014 to December 2015, 767 females were analysed along the north-west coast of the Mexican Pacific Ocean. Both immature and mature females were represented in the total length ( L T ), which ranged from 81 to 440 mm, and the smallest mature female was 92 mm (new record for the species). Gonadal maturity phases were assigned through histological analysis. A I G threshold value I cut was established using the lower whisker value for maturity phase spawning capable (2.06%). The monthly variation of I G supported the annual spawning seasonality, and the presence of reproductively active mature females I G ≥ I cut coincided with the observed periods with histological data and the peaks for both seasons 2014 and 2015. Also the presence of reproductively inactive I G < I cut mature females confirmed the nonreproductive season observed from January to April 2015. Estimates of L 50 were based on the cumulative proportion of reproductively active mature females: both datasets showed a 'bumpy trajectory'. Considering the functional form of data and models, a second objective was to verify if each dataset presented a simple or double sigmoid trajectory and select the most suitable model through the Akaike information criterion. For both datasets, the best fitted model was the double sigmoidal M DS , while the single sigmoidal M SS had low performance and did not have statistical support. The M DS provided a L 50 value ca. 254 mm L T for both data sets. A trade-off between the model's correct fit and a reliable L 50 value was found, but this fact is not always considered when calculating the maturity, resulting in biased parameters. Correct data fitting may seem trivial, but the consequences for the conservation of immature individuals could be dramatic, affecting the population recruitment. In conclusion, the histologically calibrated I cut was suitable for classifying females of S. annulatus into reproductively inactive or active types, with an agreement percentage of 99%. The I cut = 2.06% can be useful for subsequent studies for this species.
Assuntos
Reprodução , Tetraodontiformes , Feminino , Animais , Gônadas , Estações do Ano , BiologiaRESUMO
The size at which a certain fraction of a fish population reaches sexual maturity is an important parameter of life history. The estimation of this parameter based on logistic or sigmoid models could provide different ogives and values of length at maturity, which must be analyzed and considered as a basic feature of biological reproduction for the species. A total of 305 individuals of Narcine entemedor (N. entemedor) were obtained from artisanal fisheries in the Bahía de La Paz, Mexico. For the organisms sampled, sexes were determined and total length (TL) in cm was measured from October 2013 to December 2015. The results indicated that the females were larger, ranging from 48.5 cm to 84 cm TL, while males varied from 41.5 cm to 58.5 cm TL. The sex ratio was dominated by males ranging from 45-55 cm TL, while females were more abundant from 60 to 85 cm TL. Mature females were present all year long, exhibiting a continuous annual reproductive cycle. The length at maturity data were described by the Gompertz model with value of 55.87 cm TL. The comparison between models, and the model selection between them, showed that the Gompertz model had maximum likelihood and smaller Akaike information criterion, indicating that this model was a better fit to the maturity proportion data of N. entemedor.
RESUMO
A total of 228 sampling stations were visited for benthic fauna during a series of oceanographic cruises in the Gulf of California, west coast of the Baja California Peninsula, and Eastern Central Pacific from year 1991 to 2014. Among others, three fish species of the genus Dibranchus were caught in 28 stations. Of these, D. spongiosa was the most common and abundant. Close inspection of this fish revealed the presence of a new species of parasitic copepod, Chondracanthus dibranchi sp. nov., found in the gill cavity of seven specimens of D. spongiosa. Chondracanthus dibranchi sp. nov. seems to be morphologically related to C. psetti and C. janebennettae. The female of C. janebennettae can be separated from these other two congeners by the general shape of the head and abdomen, by the number of teeth on the mandibular blade, and by the general body shape. Chondracanthus psetti and C. dibranchi sp. nov. share the relative lengths of legs 1 and 2, the relative size and shape of the genito-abdomen, and the conical attenuating lateral processes on the trunk of the female. The females of these two species can be separated by the shape and armature of the antennule, shape of the antenna, the claw of the maxilliped, the rami of leg 1 and 2 and posterior processes, the head region, and by the position of the lateral processes of the trunk. An amendment to Tang's (2007) key to the species of Chondracanthus is proposed.
Assuntos
Copépodes/classificação , Copépodes/genética , Peixes/parasitologia , Abdome/anatomia & histologia , Animais , Antenas de Artrópodes/anatomia & histologia , Copépodes/anatomia & histologia , Feminino , Doenças dos Peixes/parasitologia , Brânquias/parasitologia , Cabeça/anatomia & histologia , México , Oceano Pacífico , Especificidade da EspécieRESUMO
Abstract:The genus Bathypterois (tripod fish) comprises 19 species of deep-sea fishes distributed worldwide. The biology and distribution of the species of this genus are relatively poorly known throughout the Eastern Central Pacific (ECP). This work aims to update the geographic and bathymetric distribution of species of Bathypterois throughout the ECP. To describe the influence of depth, temperature and dissolved oxygen concentrations (DO) on latitudinal and depth distribution of members of the genus throughout the Mexican Pacific, 51 specimens of B.atricolor (12 trawls) and 112 of B. ventralis (18 trawls), collected during TALUD project, were analyzed. Bathypterois atricolor had broader environmental niches (depth: 0.47, temperature: 0.46, DO: 0.39), and inhabits deeper and colder sites (Electivity positives: > 1 000 m, < 3.2 °C, 1.0-1.62 mL/L) than B. ventralis, which had narrow environmental niches (depth: 0.34, temperature: 0.32, DO: 0.28), with high affinity to warmer sites and lower DO concentrations (Electivity positives: 778-1 400 m, 3.3-5.8 °C, < 1.0 mL/L). Both species used different environmental strata (niche overlap; depth: 0.34, temperature: 0.32, DO: 0.28). The adaptation of B. atricolor to live in a broad range of DO concentrations explains its almost circumglobal distribution, while B. ventralis lives almost permanently in the Oxygen Minimum Zone (< 0.05 mL/L), so the DO could be a limiting factor, reducing its potential geographic and bathymetric distributions. None of these species had been previously recorded in the central Gulf of California, and B. ventralis had not been recorded along the West coast of Baja California. This study confirms that both species have a continuous distribution within the ECP, our new records extended the known northernmost range for B. atricolor by 886 km (from 22°46' N to 30°45' N) and for B. ventralis by 645 km (from 21°18' N to 27°07' N). Rev. Biol. Trop. 65 (1): 89-101. Epub 2017 March 01.
ResumenEl género Bathypterois (peces trípode) está conformado por 19 especies de peces de profundidad, distribuidas alrededor del mundo. La biología y distribución de las especies de este género son relativamente poco conocidas a lo largo del Pacífico Centro Oriental (POT). Este trabajo tiene el objetivo de actualizar la distribución geográfica y batimétrica de las especies del género Bathypterois a lo largo del POT. Para describir la influencia de la profundidad, temperatura y concentraciones de oxígeno disuelto (OD) sobre la distribución latitudinal y batimétrica de miembros del género Bathypterois en el Pacífico Mexicano, se analizaron 51 especímenes de B.atricolor (12 arrastres) y 112 B. ventralis (18 arrastres), recolectados durante el proyecto TALUD. Bathypterois atricolor presentó nichos ambientales más amplios (profundidad: 0.47, temperatura: 0.46, OD: 0.39) y habita sitios más profundos y fríos (Electividad positiva: > 1 000 m, < 3.2 °C, 1.0 - 1.62 mL/L) en comparación con B. ventralis, que tiene nichos ambientales reducidos (profundidad: 0.34, temperatura: 0.32, OD: 0.28), con alta afinidad por sitios más cálidos y bajas concentraciones de OD (Electividad positiva: 778-1 400 m, 3.3-5.8 °C, < 1.0 mL/L). Estas especies utilizaron distintos estratos ambientales (traslape de nicho; profundidad: 0.34, temperatura: 0.32, OD: 0.28). La adaptación de B. atricolor para vivir en un amplio intervalo de concentraciones de OD explica su distribución casi circunglobal, mientras que B. ventralis vive casi permanentemente en la Zona de Mínimo Oxígeno (< 0.05 mL/L), por lo que el OD puede ser un factor limitante, reduciendo su posible distribución geográfica y batimétrica. Ninguna de estas especies había sido registrada anteriormente en el centro del Golfo de California, así como B. ventralis no había sido reportada a lo largo de la costa occidental de Baja California. Este estudio confirma que ambas especies tienen una distribución continua dentro del POT, nuestros nuevos registros extienden la distribución más norteña conocida para B. atricolor en 886 km (de 22°46' N a 30°45' N) y en 645 km para B. ventralis (de 21°18' N a 27°07' N).
Assuntos
Animais , Ecossistema , Distribuição Animal/fisiologia , Peixes/fisiologia , Oxigênio/análise , Água do Mar/química , Especificidade da Espécie , Temperatura , Oceano Pacífico , Dinâmica Populacional , Análise Multivariada , Aclimatação/fisiologia , MéxicoRESUMO
The genus Bathypterois (tripod fish) comprises 19 species of deep-sea fishes distributed worldwide. The biology and distribution of the species of this genus are relatively poorly known throughout the Eastern Central Pacific (ECP). This work aims to update the geographic and bathymetric distribution of species of Bathypterois throughout the ECP. To describe the influence of depth, temperature and dissolved oxygen concentrations (DO) on latitudinal and depth distribution of members of the genus throughout the Mexican Pacific, 51 specimens of B. atricolor (12 trawls) and 112 of B. ventralis (18 trawls), collected during TALUD project, were analyzed. Bathypterois atricolor had broader environmental niches (depth: 0.47, temperature: 0.46, DO: 0.39), and inhabits deeper and colder sites (Electivity positives: > 1 000 m, < 3.2 °C, 1.0-1.62 mL/L) than B. ventralis, which had narrow environmental niches (depth: 0.34, temperature: 0.32, DO: 0.28), with high affinity to warmer sites and lower DO concentrations (Electivity positives: 778-1 400 m, 3.3-5.8 °C, < 1.0 mL/L). Both species used different environmental strata (niche overlap; depth: 0.34, temperature: 0.32, DO: 0.28). The adaptation of B. atricolor to live in a broad range of DO concentrations explains its almost circumglobal distribution, while B. ventralis lives almost permanently in the Oxygen Minimum Zone (< 0.05 mL/L), so the DO could be a limiting factor, reducing its potential geographic and bathymetric distributions. None of these species had been previously recorded in the central Gulf of California, and B. ventralis had not been recorded along the West coast of Baja California. This study confirms that both species have a continuous distribution within the ECP, our new records extended the known northernmost range for B. atricolor by 886 km (from 22°46' N to 30°45' N) and for B. ventralis by 645 km (from 21°18' N to 27°07' N).