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Dolphinfish (Coryphaena hippurus) samples were collected over four consecutive years from four locations in the eastern central Pacific to evaluate the genetic variation in a 751 bp segment of the mitochondrial NADH subunit 1 (ND1) to test for the presence of genetic population structure. Sequence analyses revealed no significant differences among collections from the same location in the different years sampled nor between locations. Mismatch distributions, estimations of population expansion parameters, and neutrality tests revealed significant fluctuations in population size in coincidence with past glacial and interglacial periods during the late Pleistocene. The low levels of nucleotide diversities and shallow coalescence of mtDNA genealogies observed were coincident with the estimated demographic parameters and neutrality tests, in suggesting the presence of important past population size fluctuations or range expansion. The prevention of the accumulated of deep lineages independantly on how it was originated, probably delayed the emergence of a population divergence process which might account for the lack of genetic differences detected. (c) 2006 Elsevier B.V. All rights reserved.

Catch and effort data of the tuna purse seine fishery and biological and socio-economic parameters of bigeye tuna (Thunnus obesus) in the Eastern Pacific Ocean were used to reconstruct the population structure for 1995-2009. The fishing mortality in recent years indicates a growing pressure on the stock, but it was found slightly under exploited. By increasing the fishing mortality would allow attaining the Maximum Sustainable Yield (MSY). The Maximum Economic Yield (MEY) can be achieved by reducing the fishing mortality rate. With a reduction of the fishing mortality in 20% per year, the stock could be restored and the benefit/cost ratio could increase allowing a sustainable fishery. Results of the simulations suggest that the best harvesting strategy to adopt would be at the MEY, which imply several benefits and a few inconvenient social and economic costs, which after a comparison with the current condition, seems to be quite acceptable. If adopted, it is convenient to apply it gradually to avoid undesirable impact from the social point of view, because it would imply a reduction of nearly 7% of the fishermen. The economic benefit would have a significant increase over 20%, these surplus income could be used to finance other economic activities to provide employment to the fishermen leaving this activity. A partir de datos de captura y esfuerzo de la flota atunera de cerco, de parámetros socio-económicos de la pesquería y de parámetros biológicos del patudo (Thunnus obesus) en el Océano Pacífico oriental se reconstruyó la estructura poblacional para el periodo 1995-2009. La mortalidad por pesca en los últimos años indica una creciente presión sobre el stock, pero se encontró que el recurso está ligeramente subexplotado. Mediante el aumento de la mortalidad por pesca y la disminución de la edad de primera captura se alcanzará el Rendimiento Máximo Sostenible (MSY). El máximo rendimiento económico (MEY) puede lograrse reduciendo la edad de primera captura y la tasa de mortalidad por pesca. Con una reducción de esta mortalidad en 20% anual, e puede recuperar el stock y la razón beneficio/costo aumentaría permitiendo una pesca sostenible. Los resultados de las simulaciones sugieren que la mejor estrategia de captura a adoptar sería el MEY, que implica varias ventajas y pocos inconvenientes sociales y económicos, que después de una comparación con la condición actual, parecen ser bastante aceptables. De adoptarse, es conveniente aplicarlo gradualmente para evitar un impacto indeseable desde el punto de vista social, porque implicaría una reducción de casi 7% de los pescadores. La ganancia económica mostró un aumento significativo mayor del 20%, lo cual se podría utilizar para financiar otras actividades económicas que proporcione empleo a los pescadores que dejan esta actividad.

Wahoo (Acanthocybium solandri) is distributed in all tropical and subtropical oceans and caught incidentally by the tuna purse-seine fishery in the Eastern Pacific Ocean (EPO). Generalized additive models (GAM) and boosted regression trees (BRT) were used to analyze relationships between presence of wahoo in logbook data from the Mexican tuna purse-seine fishery with environment, geographic area and set type (unassociated, associated with dolphins or floating objects set). Model performance was evaluated using changes in deviance in the fitted models and the area under the receiver operating characteristic curve (ROC). Results indicate little difference between the performance of GAM and BRT models. Both methods were consistent with predictions of presence of wahoo with respect to the variables used. Set type was the single most important predictor of variation in presence of wahoo, with highest probability of incidental catch in sets made on floating objects. With respect to environmental factors, sea surface temperature (20-25 °C) and chlorophyll-a concentration (

In this study we investigate the reproductive dynamics of the common dolphinfish (Coryphaena hippurus), using gonads obtained from four locations in Baja California Sur. From August 2004 to November 2006, 2839 dolphinfish were collected (1399 males and 1440 females), ranging in size from 42 to 155 cm fork length (FL). The sampling revealed a marked seasonality in abundance with 65% of samples obtained in summer-autumn. Histological analyses of 320 gonads (84 males and 236 females) showed maximal reproductive activity during the months of increased abundance, which coincided with increased sea surface temperatures (28-308C). No immature individuals were sampled and individuals of both sexes were shown to have advanced reproductive activities. Ovarian development showed different kinds of oocytes, indicating that dolphinfish have asynchronous gonadal development. The low gonadosomatic indices were attributed to post-spawning individuals sampled from August to October. Mean batch fecundity (number of oocytes) estimated for 24 females was 279,383. The sex ratio for the analysed period did not differ significantly from 1:1.02 (P-0.05). It was determined that 50% of all individuals reached maturity at an average length of 80 cm FL. Using reproductive indicators it was determined that the season of maximum reproduction for dolphinfish in the southern Gulf of California occurs mainly during the second half of the year, in the warm months of summer-autumn.

The objective of the study was to identify key elements of the feeding ecology of the dolphinfish, which is a high tropic predator important for sport and artisanal fishing in the Mexican Pacific. Feeding habits were investigated during the years 2000–2003. This species is seasonal in the southern Gulf of California and probably remains there because of the abundant prey. The contents of 232 dolphinfish stomachs were analyzed, identifying 98 prey species, although only eight of these were well-represented in the diet. The most important prey by weight was the fish Hemiramphus saltator, however by number and frequency of occurrence was the crustacean Hemisquilla californiensis. No differences in the diet were found between males and females, although there was an ontogenic diet shift between seasons. There was no relationship between dolphinfish size and prey size, because dolphinfish fed preferentially on prey with an average size of 4.7 cm.

Fish eggs need to contain sufficient reserve substances necessary for the development of the embryo. During the phase of vitelogenesis, females require food rich in proteins and lipids to produce the vitelogenin stored mainly in the yolk, because it is the only source of food in the embryo during the larval stage until the larvae receives its first food. The importance of the lipid composition for a good gonadal development and success in the survival of the larvae has been recognized in recent years. Currently the information about the composition of the lipids in the oocyte of large pelagic fish, including the dolphinfish Coryphaena hippurus, is scarce. Our goal then is to analyze the variation in the lipids (triglycerides) in the oocyte of females of this species collected off Baja California Sur. By using the digital analysis of histological images, we obtained a lipid index, which gave us a relative quantification of the lipids in the oocyte of each female. Variations in the composition of the lipids between years were detected, an increased trend between the average oocyte diameter and the fork length was found.

This paper shows the difficulty to visually to illustrate the variability of the species composition of sampled sets landed by purse seiners in the Indian and Atlantic Oceans. When large numbers of sets have been sampled during the last 30 years, it is still quite difficult to visualize the heterogeneity of their species compositions. This paper proposes to use the ternary plots proposed by De Finetti to solve this problem. These ternary plots have been drawn as examples on the Free and FAD schools sets sampled in the Indian and Atlantic oceans during the 2002-2008 period. These ternary plots have been drawn as examples using 3 different plotting methods, but other alternate improved methods could also be envisaged following the discussion of this working document

In the eastern Pacific Ocean (EPO), dolphinfish (Coryphaena spp.) are caught incidentally by the tunapurse-seine fishery; therefore, the records of this fishery are a good source of information to analyzethe distribution of dolphinfish. To determine the spatiotemporal distribution of dolphinfish and catchvariability in the three types of tuna-fishing sets (on schools associated with dolphins or with floatingobjects, or on unassociated schools), statistical analyses were made of the 1998–2005 records takenby scientific observers on board tuna-fishing vessels. The incidental catch did not show a well-definedannual or seasonal distribution pattern. Two high catch areas were observed, the first located in Mexicanoffshore waters (15–25◦N), with 15% of the total catch, and the second located in offshore watersof the central EPO (0–10◦N), with almost 60% of the total catch. The incidental catch was significantlydifferent among years and seasons (H7,780 = 54.6, p < 0.05 for years, and H3,780 = 42.7, p < 0.05 for seasons),the greatest catch being recorded during 1999 and the first two quarters, respectively. Sets on floatingobjects recorded most of the incidental catch of dolphinfish, followed by unassociated sets, whiledolphin-associated sets recorded the lowest catch. Almost 80% of the total catch was fished in waterswith sea-surface temperatures between 25 ◦C and 28 ◦C. The mean size of dolphinfish was significantlydifferent (H2,777 = 12.8, p < 0.05) by set type, but the smallest specimens caughtwere associated with floatingobjects. Among sets associated with floating objects, the incidental catch of dolphinfish was greatestin sets on logs, branches, etc. (PALO sets), though those on FADs (fish-aggregating devices)were the mostnumerous in the central EPO.

This paper discusses the various potential biases associated with species and size sampling carried out in the Atlantic Ocean during landings of purse seiners. This paper is a follow- up of the 4th Meeting of the WCPFC Scientific Committee during which there were serious doubts expressed about the bias faced by the sampling schemes used in the Atlantic since 1980. The conclusion of the paper is that the sampling scheme currently used in the Atlantic appears to be consistent and satisfactory, but that minor potential biases in this sampling should be better identified and reduced by improvements in the current sampling and data processing. It is recommended that an international working group be organized to identify these uncertainties and to improve the multi-species sampling schemes and the data processing of their results.

Laguna Ojo de Liebre is part of El Vizcaíno Biosphere's Reserve, one of the largest protected natural areas in the world. The contribution of seaweeds to the lagoons' total biomass had not been previously quantified. The purpose of this study was to evaluate the spatial and temporal variations of seaweed biomass in the lagoon. Seaweed samples were taken every season during 1995 at six sampling stations distributed throughout the lagoon. Total specific biomass of seaweeds was at its peak in the summer, and minimum in spring. The highest total annual biomass was found at Isla Brosa in the lagoon's central portion, and the lowest in El Dátil at the head. The seasonal and spatial variation of biomass in the lagoon is related with species richness and environmental parameters. Potentially important species in terms of biomass, wide spatial and temporal distribution, and potential use were: Spyridia filamentosa, Entheromorpha clathrata, Dasya baillouviana, Hypnea valentiaeand Sargassum sinicola .Using PCA three groups of stations were defined: one chiefly at the lagoon's mouth, another comprised the islands in the central portion, and the last in the lagoon's head.

The influence of the lunar phases on the catch-per-unit effort (CPUE) of the striped marlin (Tetrapturus audax) captured by the Cabo San Lucas, Baja California Sur, Mexico sport-fishing fleet from October 1987 to June 1989 was analyzed. The information is from 3 377 fishing trips by 13 vessels that represent about 10 % of the fleet. The analysis of the CPUE showed a maximum in January 1988 and a minimum in February 1989. Taking into account the knowledge of the factors that had influence on the fishing success is important in the resource management. No significant difference during the full moon compared with results during other lunar phases was found.

Climate regime shifts in the Northeast Pacific appear to have forced population size changes associated with major geographical variations in the position of the center of distribution and bulk of biomass of Pacific sardine (Sardinops caeruleus). These findings help explain the disappearance of sardines around 60 years ago at the northern part of the California Current System and their return following the 1980s. The spatial processes described here differ from those suggesting that environmental regime shifts lead to progressive increase–decrease of stock abundance associated with homogeneous expansion–contraction of its distribution range around a fixed geographical center. Sardine population changes are seemingly related to environmental variability, whereas the spatial pattern of abundance for the northern anchovy (Engraulis mordax) appears to be inversely related to sardine population abundance. Anchovies increased where and when sardines were either absent or at a low population level. Thus, from the long-term and large-scale perspective, neither sardine nor anchovy populations conform to the simple homogeneous geographical range changes usually assumed. The sardine population changes its location within the ocean habitat in an evolving progression over a multidecadal time scale.

The red alga Gelidium robustum is important,because of its commercial exploitation in Mexico as araw material for the agar industry, providing 10% ofthe world production of agarophytes. In recent years,its annual harvest in Mexico has shownobvious,variations partly because of an increasedharvesting effort, but also because of environmentalchanges. An analysis is presented of the effect thatinterannual variability of the sea surfacetemperature, wind speed, and upwelling index had onthe relative abundance of this alga from 1980 to 1990.The results indicate a close relation betweenenvironmental fluctuations and the relative abundanceof this species. The response of G. robustum tothe different environmental conditions has not alwaysbeen equal. During El Niño 1982–84, the seasurface temperature was the most important factor andthere was a high negative correlation with therelative abundance. A lag period of three monthsshowed a positive correlation with upwelling index andwind speed. Under normal conditions and during LaNiña, the relative abundance of the alga showed apositive correlation with the sea surface temperature. For the upwelling index and wind speed, therelationship was similar to that during El Niño.

En este trabajo se relacionan gráficamente la distribución de las concentraciones de pigmentos fotosintéticos derivadas de composiciones mensuales de imágenes producidas por la lectura del sensor Coastal Zone Color Scaner del satélite Nimbus-7, con mapas de abundancia de atún aleta amarilla derivados de los datos de bitácoras de la flota atunera mexicana para el periodo 1984-1986. Los resultados del estudio muestran una relación entre la distribución de frentes de color, independientemente de la concentración de pigmentos. Por otro lado, mediante el uso de series construidas con los promedios mensuales en el área, se reconoce un desfazamiento de aproximadamente una estación (tres a cinco meses) entre los valores máximos de abundancia de atún y concentración de pigmentos.

El estudio del nicho trófico tiene como finalidad conocer el papel funcional desde el punto de vista alimenticio de una especie en el ecosistema y sus interacciones intra e interespecíficas. En el caso particular del marlín rayado (Kajikia audax), marlín azul (Makaira nigricans) y dorado (Coryphaena hippurus), considerados como pelágicos mayores, se desconocen las interacciones entre ellos y su papel trófico en el ecosistema pelágico de la boca del Golfo de California. Por tal motivo el objetivo de este trabajo es determinar el nicho trófico de las tres especies mediante el análisis de contenido estomacal e isótopos estables de 13C y 15N. Para llevar a cabo lo anterior, se realizaron muestreos mensuales de la flota de pesca deportiva de Cabo San Lucas, B.C.S. y Mazatlán, Sinaloa durante el periodo 2005-2007. Se aplicaron índices ecológicos asociados al contenido estomacal, mientras que en el caso de los isótopos estables se consideró la desviación estándar como medida de dispersión asociada a los valores promedios de C y N. Los resultados muestran que el marlín azul es un depredador tope (PT= 4.5 ±0.5) que presenta una especialización hacia un solo tipo de presa (Auxis spp.), mientras que el marlín rayado es un depredador de menor nivel trófico (PT= 4.1 ±0.4) que se alimenta de especies de hábitos epi y mesopelágicas mediante una estrategia de alimentación mixta en la que algunos individuos tienen una dieta especializada y otros una generalizada. Por último, el dorado es un carnívoro secundario (PT= 3.9 ±0.53) que se alimenta de presas distribuidas en la columna de agua (epi, meso, bati-pelágicas), presentando una dieta generalizada y con mayor variación individual en la amplitud de dieta. Los valores isotópicos mostraron diferencias significativas en carbono y nitrógeno entre las tres especies. Por tal motivo, la coexistencia espacio-temporal observada pudiera estar relacionada con la plasticidad en el uso de áreas y recursos.

El Océano Pacífico Oriental es la región oceánica donde la relación atún-delfín aporta las mayores capturas, en el caso de la flota mexicana de cerco la actividad se centra principalmente en este tipo de cardúmenes, sin embargo, cerca de las costas mexicanas también la pesca de cardúmenes no asociados cobra importancia. En este estudio se analizan las capturas obtenidas a lo largo del Pacífico Mexicano durante el periodo de 1998-2004, con la finalidad de determinar las condiciones que favorecen la presencia de uno u otro tipo de indicador. La Información ambiental se manejo en cuadrantes de un grado con una temporalidad mensual, las variables analizadas corresponden temperatura superficial del mar (TSM), concentración de clorofila a (Cla) y velocidad del viento (VV). Mediante la aplicación de un análisis de discriminante se determinaron cuatro zonas a lo largo de las costas mexicanas y cuadrantes transicionales entre ellas, de igual manera, esta metodología se aplicó para ver si existían diferencias entre los cuadrantes en los que se registró captura, definidos para este análisis en tres tipos: aquellos en los que solo se capturaron cardúmenes asociados a delfín, los que tuvieron solo presencia de cardúmenes no asociados y un tercer grupo en los que se registró la presencia de ambos tipos de pesca. Para evidenciar los procesos que pudieran determinar la presencia de los distintos indicadores y relacionarlos con zonas específicas se aplicó análisis de componentes principales (ACP). Los patrones de variabilidad más notables se obtuvieron por medio de un análisis de Funciones Empíricas Ortogonales (FEOs), la variabilidad interanual fue la principal fuente de variación de la TSM, en el caso de la Cla y la VV este análisis sugiere regímenes distintos a lo largo del periodo de estudio. La mayoría de los cuadrantes registraron capturas de un solo tipo de indicador, se detectaron diferencias significativas en los valores de las variables ambientales registradas en cada uno. Las zonas con mayor dinámica son las que aportan mayores capturas debido a que la variedad de condiciones Permiten la presencia constante de cardúmenes de diferentes tipos.

El dorado (Coryphaena hippurus) se encuentra reservado a la pesca deportiva dentro de una franja de 50 millas de las costas de México; sin embargo se conoce que soporta una pesca ilegal por flotas artesanales de diferentes regiones, además de ser la principal especie que capturan incidentalmente las flotas palangrera y atunera. La Carta Nacional Pesquera la considera como un recurso con potencial de desarrollo, por lo que suponen que podría soportar una pesquería comercial en la zona costera. Ante esta perspectiva, la elaboración de un plan de manejo adecuado necesita estar sustentado en un conocimiento de la biología y dinámica de la especie, los cuales a la fecha son escasos. Por ello, para entender la dinámica poblacional de la especie, se tuvo como objetivo principal abordar aspectos de su biología reproductiva, edad, crecimiento y mortalidad del dorado capturado en la región de Baja California Sur. Durante el 2004 a 2006 se colectaron un total de 2839 dorados (1399 ♂ y 1440 ♀) en cuatro localidades de esta región, en un intervalo de tallas de 42 a 155 cm de longitud furcal (Lf). Se encontró una relación lineal significativa (r2 = 0.56 ♂ y r2 = 0.49 ♀), entre el radio de la escama y la Lf de los dorados. Se determinó la edad de 497 individuos (246 ♂ y 251 ♀), definiendo que las marcas de crecimiento se forman anualmente durante los meses de octubre y noviembre, lo que coincide con el ciclo reproductivo y la variación de la temperatura superficial del mar. Las relaciones peso-longitud indicaron un crecimiento de tipo alométrico negativo, significativo para ambos sexos. Las estimaciones de los parámetros de la ecuación de crecimiento de Von Bertalanffy para machos fueron (K=1.14, t0= -0.10 y L∞=122.7), para hembras (K=1.68, t0=-0.09 y L∞=102.8) y para sexos combinados (K=1.20, t0=-0.13 y L∞=117.4). Estos parámetros sugieren que esta especie tiene una tasa de crecimiento rápido durante los primeros 6 meses tanto en longitud como en peso. Las lecturas de las marcas de crecimiento en las escamas mostraron que la pesca deportiva incidió sobre 8 grupos de edad de 0 a 3.5 años, siendo los más abundantes los grupos de 0.5 a 1.5 años para ambos sexos. Con el método de captura linealizada basada en edades, se encontró un valor de mortalidad total (Z) de 2.59 por año y mediante el método alternativo (Beverton-Holt) el valor fue de XVIII.

El atún aleta amarilla es la especie más capturada por la flota atunera mexicana (83%), con capturas promedio de 125,200 t en los últimos años y ocupa el segundo lugar a nivel nacional en el valor comercial de las especies marinas extraídas. La flota mexicana está constituida por 54 barcos cerqueros y 10 vareros, ocupando el primer lugar en la capacidad de acarreo de las principales flotas que pescan atún en el océano pacifico oriental. En el presente estudio se analiza la relación entre la captura y la abundancia relativa (captura por lance estandarizado: CPLE) con la temperatura superficial del mar (TSM), perfiles térmicos, vientos, índices de surgencia, concentración de clorofila "a" obtenida a través de imágenes de satélite del Seastar, así como con la topografía en el noroeste de México. Los resultados mostraron que las mayores capturas se registraron entre los 22-26°C de TSM. En promedio tanto las capturas como la abundancia relativa fueron mayores en áreas con un perfil térmico estratificado. Las mayores capturas y abundancias relativas, así el mayor número de lances exitosos, se obtuvieron cuando la isoterma de los 20°C se encontró a profundidades menores de 70 m. El mayor esfuerzo pesquero fue aplicado en áreas en las que se observaron velocidades de viento de 5-6m/s y rotación del esfuerzo del viento en la superficie del mar positivo. Con respecto a los índices de surgencia, se observo que al aumentar estos la abundancia relativa del atún aleta amarilla se incremento. La mayor CPLE se presento cuando la concentración de clorofila "a" fue más alta, no encontrándose cercanas a las de mayor concentración de clorofila "a". No se observaron diferencias significativas entre la CPLE de los bajos y sus alrededores en forma global. La mayoría de las capturas y de los lances registrados se realizaron en la boca del Golfo de California.