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Knowledge of the population dynamics and changes in the abundance of Pacific sardine fishery is relevant for fishery management. In this study, an integrated catch-at-age model (ASAP) was performed on 47 fishing seasons (1971−2018) of Sardinops sagax in the Gulf of California, including five indices of relative abundance (survey catch rate, acoustic surveys, egg and larvae, spawning probability, and bird diet index). The ASAP model showed the importance of age group 0 (recruits); this is the most important age group in the Pacific sardine fishery, and its abundance has consequences for the variability of the total abundance of the species. In this study, the spawning and acoustic indices denoted the changes in abundance of Pacific sardine population better than the survey catch rate and bird diet ratio. Historically, the total biomass is estimated to have varied from 461 thousand to 4.82 million t. In the 1970s and 1980s, a peak biomass close to three million tons was reached, and in the second peak from the mid-1990s to the late 2000s, the total biomass varied between 3.26 and 4.82 million t. When the spawning biomass was at least 750 x 103 t, the recruitment (age group 0) showed high values, promoting high catches in the subsequent years. The annual fishing mortality estimates did not show a rise related to the periods of high harvestable biomass; therefore, the catch records were low in comparison to the harvestable biomass estimated from ASAP, and the annual fishing mortalities were less than 0.22 during periods of high abundance. The changes in biomass and the variability observed in the Pacific sardine fishery were validated for the model diagnostics; the retrospective patterns did not identify poor fits to data, therefore the robustness of the model can be used for management purposes. According to the Kobe phase plot, the Pacific sardine fishery in the Gulf of California has been fully exploited with an apparent stable level of harvest.

The cannonball jellyfish Stomolophus meleagris display colour variations from blue to purple, and different pigmentation patterns on the umbrella surface. Although these colour phenotypes are commo...

Graceful mojarra (Eucinostomus gracilis) is an important component of the ichthyic fauna of lagoon systems but knowledge of its population aspects is scarce. Monthly samples in the Magdalena-Almejas Lagoon system (March-August, 2014-2017) were obtained with a trawling net. Abundance was estimated using the swept area method and its spatial variation; and the maturity size was determined using the logistic method. The sex ratio for mature and immature populations, and their length-weight relationship were estimated; FISAT was used to estimate the growth and recruitment parameters. Abundance ranged from 0.6 to 203 ind-Ha-1 with changes for each lagoon system areas and among years. Size at maturity (L50) was 132 mm in total length (TL) for the population, 129 mm TL females, and 135 mm TL males. Considering the population of the total organisms, L50 indicated that 18% were adults and 82% were juveniles. Juvenile dominance indicated that this lagoon system is used for grow-out. The smaller ratio of adult organisms does not allow asserting assertion that the priority of the area is for reproduction. E. gracilis showed moderate growth (K = 0.56 year-1) with longevity of 5.4 years and asymptotic length of L∞ = 195 mm.

Worldwide catches of cannonball jellyfish Stomolophus meleagris (Cnidaria: Scyphozoa) have increased during the last years; nevertheless, this species still lacks updated biological knowledge for its management. This research proposes that the individual growth pattern for jellyfish can be estimated in the absence of age readings through cohort follow-up over time and by multi-model inference approach (MMI). Length data were obtained during 2010–2011 in Gulf of California to obtain cohort information using a multinomial analysis and then assign age; growth model selection was based on MMI. Three cohorts were identified and the von Bertalanffy model suitably described their growth. The species has an accelerated growth with a short life cycle; cohorts one and two reached their asymptotic length, and the third one barely reached the length-at-first sexual maturity. Growth variations among cohorts could be explained by their different biological strategies where the first two prioritized asymptotic length and the third one reproduction length. The three cohorts shared a common goal for medusoid phase, which was sexual reproduction. This information could be used for estimating harvest rates or assessing their capacity for redoubling as an invasive population in coastal ecosystems. The proposed methodology may be applied in other jellyfish species around the world.

This study provides information on feeding habits of the lizardfish Synodus scituliceps, one of the most abundant and frequent species in shrimp by-catch in the demersal area in the eastern coast of the Gulf of California, Mexico. Stomach content analyses were performed on 114 organisms caught from August 2004 to March 2005, and Levin's index was applied. The most important prey species were benthic fishes: Eucinostomus currani, Opisthonema libertate, Synodus lucioceps and Paralichthys californicus. According to the Levin’s index (Bi = 0.39), S. scituliceps is a piscivorous specialist predator in soft bottoms, with similar diet in juveniles and adults.

This study provides information on the population dynamics of the smooth hammerhead shark Sphyrna zygaena in the central-southeast Pacific Ocean. The samples were obtained from artisanal fisheries from 2008 to 2013 to analyse cohorts, growth, mortality, abundance and recruitment using methods based on length and relative age and an inference multi-model. According to the von Bertalanffy growth model, the results indicated that the species showed from three to seven cohorts annually and slow growth (Wi = 57.20%): L∞ = 292.86 cm, K = 0.141 per year and t0 = -2.26. Length of sexual maturity was 239.30 and 209.10 cm at first capture; the average natural mortality value was 0.231 per year, by fishing 0.051 per year with a total mortality of 0.26 1 per year and exploitation rate of 0.15. Interannual variability was recorded in biomass with an average of 7367.24 tonnes, as well as a spatial permanence pattern. The results suggest that the La Nina event biologically favours the population in the area. The information from this study is essential for better understanding the species population and serves as a basis for future actions of management and conservation of S. zygaena.

The aim of this study was to determine the presence of the white spot syndrome virus (WSSV) in zooplankton organisms collected from an important shrimp-culture area of the Gulf of California. Environmental water parameters (temperature, salinity, dissolved oxygen, and pH) were monitored, and zooplankton was collected. Samples were sectioned according to taxonomic groups (from Phylum to Family) for the detection of WSSV via PCR. A total of 52 zooplankton taxa were identified, of which crustaceans were the most abundant (82%). From the 228 WSSV diagnoses performed, 35% were positive. Moreover, from 32 taxa recorded at least one positive result was observed during the study, and only 13 were negative in all tests. The highest prevalence was observed in three taxa of copepods, brachyurous and bivalves. However, considering prevalence and frequency of occurrence, it was determined that up to 12 taxa could be considered as high-risk vectors. Finally, a significant correlation was found between the number of diagnoses per station with biovolume (rs = 0.817) and taxa richness (rs = 0.995). The results suggest that zooplankton diversity and abundance are associated with virus dispersion; moreover, these results demonstrated that the dispersion capacity of the virus through different taxa has been probably underestimated in recent years.

Background. The presence of Laemonema verecundum (Jordan & Cramer, 1897) had not been previously reported at depths less than 666 m. Goals. The objective of the research was to study the bathymetric distribution of L. verecundum. Methods. In the eastern continental shelf of the Gulf of California, 648 specimens of L. verecundum were collected during two experimental research cruises in September 2004 and February 2005. Results. Specimens were collected at depths between 165 and 483 m, where temperatures ranged between 9.5 and 19.9° C, and average oxygen concentration was 1.7 mg/l. Conclusions. This new record expands the known bathymetric distribution range of this species inhabiting shallow waters in the gulf.

Biometric relationships were estimated for the three most important shrimp species on the coasts of the Gulf of California, Mexico. Individuals were obtained from six lagoon systems, and offshore sites along the east coast of the Gulf of California, mainly in the state of Sonora, between March and September of 2015 and 2016. A total of 25,764 individuals of Penaeus stylirostris, Penaeus vannamei and Farfantepenaeus californiensis were analyzed; the length and weight regression for the females, males and combined sexes showed a high correlation between variables. Additionally, some statistically significant differences were found in the linear length and weight relationships (P < 0.05) between sexes. This study reports the length-weight parameters for a key site of the shrimp fishery, it covers a wide range of sizes for each species and was based on the stages late inshore juvenile and offshore of the shrimp lifecycle; as such, this study provides useful information for future estimations of indispensable parameters for stock assessment analyses.

Aspects of distribution and population dynamics were assessed in two rock shrimp species of the genus Sicyonia . Samples were obtained by sea bottom trawling in depths from 50 to 460 m during two research cruises on board the B/I BIP XII in the Gulf of California, Mexico. Taxonomic identification of specimens was performed; measurements of individual length and weight data were taken to obtain biometric relationships and length frequencies. Growth parameter estimations were performed adjusting the von Bertalanffy growth model (VBGM), and the recruitment pattern was obtained by the ELEFAN II method. Longevity was estimated with the Taylor equation, natural mortality with six different models, and length at first maturity by the logistic model. A total of 67 fishing trawls were monitored, and 1,330 specimens were caught (65% S. ingentis ; 35% S. penicillata ) in the depth range from 124 to 338 m. Sex ratio (F:M) was 1.0:1.6 for both species; weight and length relationships (both sexes) showed an isometric growth for S. ingentis and positive allometric growth for S. penicillata . Growth parameters and longevity values were moderate (1.71 and 1.81 years) with age at first maturity around six months for both species. The recruitment pattern showed continuous periods all year long, with a notable peak from November to May. Average natural mortality was 2.47 for S. ingentis and 2.35 for S. penicillata . Distribution and population dynamics information reported in this study for these two shrimp species should be considered as base knowledge in subsequent studies on fisheries management in the Gulf of California.

RESUMEN. Se presenta la composición de especies de peces y sus aspectos biogeográficos de la Laguna Las Guásimas, localizada en el sector central del Golfo de California. Se realizaron siete campañas estacionales de muestreo y las colectas se efectuaron con tres artes de pesca: atarraya, chinchorro de línea y red de arrastre. Se observaron 95 especies representadas por 16 órdenes, 38 familias y 67 géneros. Las familias mejor representadas por su número de especies fueron: Carangidae, Sciaenidae, Haemulidae, Paralichthydae, Engraulidae y Gerreidae. Además se identificaron tres especies endémicas del Golfo de California (Micropogonias megalops, Leuresthes sardina y Pleuronichthys ocellatus). El análisis de afinidad biogeográfica mostró una alta dominancia de especies distribuidas en el Pacífico Oriental Tropical (Provincia de Cortés y Panámica) y especies transicionales entre la Provincia de California y el Pacífico Oriental Tropical (POT). Utilizando investigaciones sobre peces efectuadas anteriormente en la localidad, se realizó una comparación entre las especies previamente registradas en la localidad y las registradas en esta investigación, utilizando como indicadores la vulnerabilidad y resiliencia. Se observaron cambios en la estructura de la comunidad a lo largo de tiempo, que pudieran ser inducidos por cambios ambientales, actividades antropogénicas como la pesca y/o la dinámica del ecosistema. La mayoría de las especies que son nuevos registros (84%), mostraron vulnerabilidades de moderadas a altas, enfatizando la alta importancia de la laguna como área de crianza y protección de estas especies.

Jellyfish are non-model organisms that have brought the scientific community's attention over the last decades since the frequency and intensity of these species blooms around the world have increased significantly. The occurrence of blooms has been hypothesized due to the rise in seawater temperature associated with climate change. This fact has promoted an increased interest in studying jellyfish metabolic responses to face thermal stress and maintain cell homeostasis. In this study, the response of the cannonball jellyfish Stomolophus meleagris to short-term exposure to different temperatures was evaluated. The survival and respiratory rates, and the concentration of glucose, L-lactate, glycogen, ATP, and total soluble protein in the umbrella of adult jellyfish were measured. Low survival rates at extreme temperatures (18 and 33 °C) and an increase in the jellyfish respiratory rates were observed as seawater temperature raised. Rapid changes were detected in energy substrates such as glucose and glycogen that significantly varied at extreme temperatures and longer exposure periods. L-lactate levels increased after 2 h of exposure, and then remained steady at longer times of exposure. Soluble protein concentration decreased significantly in jellyfish exposed to extreme temperatures, and ATP increased after exposure to non-optimal temperatures (18, 28, and 33 °C). These results suggest that S. meleagris faces temperature changes through rapid metabolic responses that use energetic reserves, activate anaerobic metabolism, and display a remarkable ability to synthesize ATP and maintain energy, even at long exposure.

Developing countries may face many obstacles in managing their resources and in assigning conservation status to certain groups or species. One of the main obstacles is the lack of basic and reliable information on habitat of species or ecosystems. Sustainable species management is difficult to attain without this information. A key piece of information about any resource is their distribution and abundance. Shrimp of the genus Sicyonia are poorly known globally in their biology although they have been exploited in several parts of the world. This study analyzed their distribution, abundance and size structure in the Gulf of California (GC) and the western coast of the Baja California Peninsula (WCBCP). From a total of 207 trawling tows performed (73 in the GC and 134 in the WCBCP) at depths from 45 to 600 m from 2004 to 2006, organisms (N = 4205) from four species (S. disdorsalis: 1 849; S. ingentis: 1405; S. penicillata: 965; and S. picta: 71) were caught. Of the four species found in the GC, the most frequent and abundant were S. penicillata and S. ingentis. Only three of the species, S. disdorsalis, S. ingentis and S. penicillata, were found in the WCBCP, of which S. disdorsalis and S. ingentis were the most frequent and abundant. The relationship between S. disdorsalis, S. ingentis and S. penicillata abundance and depth showed significant associations. The sizes of each species were different between the two areas. This study reports a range extension in the bathymetric distribution to 174 m for S. picta, 199 m for S. ingentis, and 259 m for S. disdorsalis, and provides more information on size structure of the four species of the genus Sicyonia still unknown to date.

First report of the dynamic populations (structure size, growth, size at first maturity, longevity, natural mortality, and recruitment pattern) of black brotula Cherublemma emmelas in the Gulf of California. Growth parameters (L, k and to) were estimated using the von Bertalanffy model. The ELEFAN II method was used to estimate recruitment pattern and Taylor’s equation to estimate longevity. Natural mortality was determined using Pauly’s equations and Jensen’s. Size at first maturity was obtained by adjusting a logistics model. During four cruises on board the BIP-XI research ship, 2148 specimens were caught at 119-499 m depth in February and May 2005, and June and October 2007. The size structure showed a bimodal distribution with lengths from eight to 32 cm of total length and 15.9 cm average size. The biometric relationship between weight and length showing allometric growth rate (b ≠ 3) for sex. The fitted growth parameters were L ∞ = 33 cm; k = 0.6 yr -1 ; t o = -0.26 year indicated a moderate growth, while longevity was five years of age. Size at first sexual maturity was 18.8 cm, and natural mortality was 0.77 yr -1 (by Pauly) and 0.90 (by Jensen). The recruitment pattern showed peaks in June and July. Normal 0 21 false false false ES-MX JA X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Tabla normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin-top:0cm; mso-para-margin-right:4.8pt; mso-para-margin-bottom:6.0pt; mso-para-margin-left:0cm; text-align:justify; line-height:150%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri",sans-serif; mso-bidi-font-family:"Times New Roman"; mso-ansi-language:ES-MX; mso-fareast-language:ES-MX;}

This study describes the first record of the whale shark Rhincodon typus association with the cannonball jellyfish Stomolophus meleagris in the Gulf of California, Mexico. Whale sharks were observed swimming and feeding among swarms of jellyfish, suggesting competition and predatory behaviour given the overlap in food preferences between both species. This finding is relevant because of the species-wide distribution and the importance of these interactions, which should be considered in conservation strategies of R. typus and management of cannonball jellyfish fisheries.

The immigration of white shrimp Penaeus setiferus (Decapoda: Penaeidae) postlarvae (Pls) into the Terminos Lagoon was studied to determine the annual pattern of abundance and its relationship with temperature, salinity, tidal current velocity, and river discharge. Zooplankton samples were simultaneously obtained fortnightly at surface, mid-water, and bottom. The nets used were 50 cm in diameter, 1.5 m in length and 505 μm mesh size. The results indicated a postlarval seasonal immigration pattern, with the lowest average density values from March to May and October to November, and significantly higher values from June to September; maximum peaks occurred in June and September. High Pls densities were obtained between one and three hours after the tidal inflow started. Temperature and salinity varied little during each sampling period and had no apparent effect on immigration, but did have an effect on the seasonal abundance cycle. The multiple regression models indicated that the tidal current velocity and the temperature explained 86% of the variation in Pls abundance during immigration to the Terminos lagoon. The larval migration varied at different levels, with highest densities occurring at a medium depth of 5 m. The Pls entered an optimal range of tidal current velocity (between 0.6 and 0.9 m3 s-1). The main entry mechanism was through the tide current of the Selective Tide Stream Transport, where the Pls could also select an optimum current velocity, avoiding the strata of higher turbulence that would imply higher energy expenditures.

The diet and feeding pattern of scyphomedusa Stomolophus meleagris (Rhizostomeae) was studied, by comparing stomach samples from different developmental stages and environmental zooplankton with the aim to determine diet composition, trophic niche breadth, selectivity and feeding overlap of this edible jellyfish species. Samplings were performed during April and December 2010 and in January 2011, in the coastal lagoon Las Guásimas (27°49′–27°54′N 110°40′–110°35′W), central Gulf of California, which consisted of zooplankton tows and jellyfish collections for stomach content. More than 39 prey items were identified in the gut contents (N = 69), from which eight taxa formed over 90% of the total. Fish eggs were considered main prey (58.6%), copepods (10.8%), veliger larvae of gastropod (13.0%) and bivalve (12.7%) were secondary prey while cirriped and decapod larvae were incidental prey (S. meleagris is a specialist predator and Pearre's index showed positive selection of fish eggs, gastropods, bivalves and cirripeds while selectivity was negative for copepods and appendicularians. The relative timing of these changes suggests that ontogenetic processes are closely related with shift in the diet, which indicates increasing predation pressure during development of the medusoid stage of this species, thus emphasizing their ecological importance in coastal ecosystems.

Algunas especies de lenguados son capturadas incidentalmente con redes de arrastre y algunas de estas son especies objetivo de una pesqueria artesanal en el Golfo de California, Mexico. Con el proposito de conocer cuantos individuos de la poblacion estan siendo capturados y cuales son los efectos de estas capturas, el objetivo de este estudio fue estimar la abundancia de los lenguados capturados incidentalmente con redes de arrastre y en una pesqueria artesanal o de pequena escala en el Golfo de California, y determinar la posible competencia entre flotas (con redes de arrastre y la flota artesanal con redes agalleras) por el mismo recurso. Las muestras fueron recolectadas durante 2002 y 2003 de 3 diferentes fuentes: prospecciones de 2 barcos de la flota camaronera comercial, prospecciones en 2 cruceros de investigacion y de una flota artesanal la cual opera a lo largo de la costa del estado de Sonora, Mexico. La abundancia de los lenguados capturados en las redes de arrastre fue estimada usando el metodo de area barrida y a traves de analisis de cohortes por talla fue estimada la abundancia para los lenguados capturados por la flota artesanal. Catorce especies de lenguados fueron identificados en las capturas incidentales con redes de arrastre, destacando Paralichthys woolmani, Etropus crossotus, Citharichthys fragilis, Citharichthys gilberti, Achirus mazatlanus y Syacium ovale. Seis de las 14 especies de lenguados capturados incidentalmente fueron tambien capturados por la flota artesanal, de la cual el 70% corresponde a P. woolmani. Se demostro que cada flota opera sobre diferentes fracciones de la poblacion, individuos de 25 a 90 cm en longitud total fueron capturados por la flota artesanal y los valores de mortalidad por pesca y tasa de explotacion fueron < 0,01, mientras que en las capturas incidentales (flota camaronera) los individuos presentaron tallas entre 4 y 20 cm, demostrando presion de pesca en los individuos juveniles cuya captura podria tener efectos negativos, debido a estos pueden ser reclutas para la pesca artesanal.

espanolLas lagunas costeras se caracterizan por su alta diversidad, riqueza y abundancia de peces, las cuales pueden ser modificadas por la variabilidad de las condiciones ambientales. El presente estudio tiene como objetivo describir la estructura de la comunidad de peces y relacionar su variabilidad estacional con los parametros de temperatura y salinidad en una laguna costera. Durante 6 campanas de muestreo se recolectaron 4.199 peces, agrupados en 95 especies. Los resultados indicaron que la riqueza, diversidad y equidad tuvieron un comportamiento estacional similar con valores mayores durante otono 2010, primavera 2011 y 2012; la abundancia fue mayor en otono 2010, verano 2011 y 2012 y la biomasa en otono 2010 y verano 2011. La relacion de la temperatura y salinidad a traves del analisis RDA con los parametros ecologicos, indico que algunas de las especies dominantes son de afinidad calida y otras de afinidad fria. Mientras que la riqueza y diversidad se incrementan durante temporadas frias, la biomasa y equidad aumentan en las temporadas de mayor salinidad; por su parte la abundancia se incrementa en temporadas calidas. Las curvas ABC mostraron estres moderado durante invierno y verano de 2012 y el MDS indico la formacion de 4 grupos, dos integrados por 2 periodos de muestreo y dos por uno solo de ellos. Los parametros ecologicos presentaron variaciones estacionales debido a la influencia de los cambios en temperatura y salinidad. EnglishCoastal lagoons are characterized by high diversity, richness, and abundance of fishes, which can be modified by high variability of environmental conditions. The present study aims to describe the structure of the fish community and related its seasonal variability with temperature and salinity in a coastal lagoon. During 6 seasonal sampling campaigns 4,199 fish were collected and grouped in 95 species. The results indicated that richness, diversity and evenness indices showed similar pattern with higher values in autumn 2010, spring 2011 and 2012, abundance was higher in autumn 2010, summer 2011 and 2012 and biomass in autumn 2010 and summer 2011. Relationship of temperature and salinity through the RDA analysis with ecological parameters indicated that some dominant species are of warm affinity and other of cold affinity. Richness and diversity increase during cold seasons, while biomass and evenness increase in seasons of higher salinity and abundance increases in warm seasons. The ABC curves showed moderate stress in winter and summer 2012 and MDS indicate the formation of 4 groups, two integrated by 2 sampling periods and two by single sampling period. Ecological parameters showed seasonal variations because they are influenced by changes of temperature and salinity.

We analyzed mantle length and age data of the whole ontogenic cycle of the jumbo squid Dosidicus gigas in the Gulf of California, Mexico, to describe its growth pattern. Several individual growth models that included asymptotic and non-asymptotic patterns were fitted to the data, and Akaike’s information criterion and multimodel inference were used to identify the model that best fit the data. The length-at-age data were divided into males and females (recruits and adults) for analysis separately and then combined to assess the overall growth pattern. The Schnute general model ( ρ ≠ 0, η ≠ 0, where ρ is the constant relative rate of the relative growth rate, η is the incremental relative rate of the relative growth rate) was the function that best described the growth of females, males and both sexes of D. gigas together. For females, the Akaike difference and Akaike weight were 0 and 0.91, respectively; for males, the Akaike difference was also 0, but the Akaike weight was 0.39, showing that alternative growth models could explain the individual growth; these growth models were the Gompertz (L0, length at time zero), Gompertz (L∞, asymptotic length) and Schnute (ρ ≠ 0, η = 0) models. We estimated the age and mantle length at which the growth rate changes for both sexes, estimating an age of 162.36 d (separately, 167.51 d for females and 158.98 d for males), and a length of 299.52 mm for the growth inflection point (separately, 312.84 mm for females and 292.86 mm for males). Once D. gigas reaches this point, the species exhibits more gradual growth until reaching an asymptotic mantle length of 859.45 mm (for females, 904.80 mm, and for males, 828.49 mm). A comparison of the growth patterns of D. gigas reported in the Eastern Pacific indicated non-asymptotic growth of this species in the Humboldt Current and Costa Rica Dome; in contrast, asymptotic growth was identified for the western coast of Baja California and Gulf of California. The reason for this difference is unclear, and this issue will be a topic of future studies.

The trophic spectrum of bothEucinostomus entomelasandMicropogonias megalops, the two most abundant fish species in Laguna Las Guásimas, Sonora, México is described in our study. A total of 21 types of prey were identified belonging to seven taxonomic groups (Crustacea, Mollusca, Annelida, Rhodophyta, Copepoda, Echinodermata and Chordata) to analyse the feeding spectra and diet breadth. The preferred prey items ofEucinostomus entomelas(Dark-spot mojarra) were Polichaeta (index of relative importance = 46.7%), followed by bivalves(36.6%), andLuidia columbia (5.6%), while those ofMicropogonias megalops(Bigeye croaker) were Portunidae (22.8%) followed by Gammaridae (20.55%) and Crustacea (18.37%). The trophic spectrum for maleE. entomelawas composed of Bivalvia and Polychaeta. Both predators showed low values in diet breadth (E. entomelas(Levin's indexBi = 0.14) andM. megalops(Levins's indexBi = 0.43)). The low trophic overlap (Cλ = 0.14) between predators suggests that both fish are not competing with each other for food resources in Laguna Las Guásimas.

Population dynamics of 3 Callinectes species: C. arcuatus, C. bellicosus, and C. toxotes are reported for the first time as incidental shrimp bycatch samplings captured in the eastern Gulf of California in a range from 10 to 77 m in depth from September 2004 to March 2005. Growth, longevity, recruitment pattern, mortality (natural, total, and by fishing), and exploitation rate were analyzed. Also, size comparison among the organisms captured by the shrimp and artisanal fishing fleets was calculated. Callinectes arcuatus (n = 737) was more abundant than the other two (C. bellicosus, n = 291 and C. toxotes, n = 344). Significant differences were shown between size distribution of C. arcuatus and C. bellicosus captured by the 2 fleets; the shrimp fleet extracted mainly organisms in sizes ranging from 50 to 120 mm in carapace width (CW), while the artisanal fleet extracted sizes from 75 to 155 mm in CW from both species. Growth parameters were moderate (L∞= 160, 173, and 168 mm; K= 1.1., 1.3 and 0.9 year-1 for C. arcuatus, C. bellicosus, and C. toxotes, respectively), estimating a 4-year longevity for the 3 species. The reproductive recruitment pattern showed a continuous period with a peak from May to August. The exploitation rate did not show a significant degree of overexploitation for any of the species. There are some differences in the parameters of population dynamics (sizes, growth) of this species based on data from commercial captures and those obtained with data of incidental captures. It is important to perform an analysis including both types of information for an adequate fishery management of these resources.

Palabras clave: Contenido estomacal, superposicion de dieta, especialista, Punta Lobos, Baja California Sur, Mexico Abstract.- The Brown smooth-hound Mustelus henlei is part of an important commercial fishery on the western coast of Baja California Sur (BCS), Mexico. However, very few studies have been performed on the feeding and reproduction biology of these sharks in Mexico. Our study is the first work focusing on this species on the western shelf (14 m to 250 m in depth) of B.C.S. We identified a total of 24 types of prey contents in the stomachs of M. henlei: 15 crustaceans, 6 fish, and 3 cephalopods. According to the index of relative importance (IRI) the main prey items for M. henlei was the pelagic red crab Pleuroncodes planipes (81.4%), followed by unidentified organic material (UOM) (15.7%), the mackerel Scomber japonicus (0.94%), and fish remains (0.84%). Conducting a prey analysis considering sex of M. henlei, P. planipes was the most important prey in both females and males, followed by UOM, and S. japonicus. Sharks found in deeper areas (120-150 m) and those caught on board the exploration ship BIP XII had a similar dietary composition to those found in the shallow waters of Punta Lobos (14-40 m) where for both regions, the dominant prey items were the pelagic red crab and UOM. According to Levin's index, M. henlei may be a specialist feeder in this area. A diet overlap according to sex, area, and size was observed. The SIMPER analysis showed a low similarity in diet in relation to sex, size, and area. According to the ANOSIM test there were no significant differences. Knowing that M. henlei shows a specialist behavior could help research studies not only for species conservation but also for its habitat and the organisms that inhabit it, which are both of vital importance for this shark.

Jellyfish (primarily scyphomedusae) fisheries have a long history in Asia, where jellyfish have been caught and processed as food for centuries. More recently, jellyfish fisheries have expanded to the Western Hemisphere, often driven by demand from Asian buyers and collapses of more traditional local fish stocks. Jellyfish fisheries have been attempted in numerous countries in North, Central, and South America, with varying degrees of success. Here, we chronicle the arrival of jellyfish fisheries in the Americas and summarize relevant information on jellyfish fishing, processing, and management. Processing technology for edible jellyfish has not advanced, and presents major concerns for environmental and human health. The development of alternative processing technologies would help to eliminate these concerns and may open up new opportunities for markets and species. We also examine the biodiversity of jellyfish species that are targeted for fisheries in the Americas. Establishment of new jellyfish fisheries appears possible, but requires a specific combination of factors including high abundances of particular species, processing knowledge dictated by the target market, and either inexpensive labor or industrialized processing facilities. More often than not, these factors are not altogether evaluated prior to attempting a new jellyfish fishery. As such, jellyfish fisheries are currently expanding much more rapidly than research on the subject, thereby putting ecosystems and stakeholders’ livelihoods at risk. Fil: Brotz, Lucas. University of British Columbia; Canadá Fil: Schiariti, Agustin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentina. Instituto Nacional de Investigaciones y Desarrollo Pesquero; Argentina Fil: López Martínez, Juana. Centro de Investigaciones Biológicas del Noroeste; México Fil: Álvarez Tello, Javier. Centro de Investigaciones Biológicas del Noroeste; México Fil: Peggy Hsieh, Y.-H.. Florida State University; Estados Unidos Fil: Jones, Robert P.. Southeastern Fisheries Association; Estados Unidos Fil: Quiñones, Javier. Instituto del Mar del Perú; Perú Fil: Dong, Zhijun. Chinese Academy of Sciences; República de China Fil: Morandini, André C.. Universidade de Sao Paulo; Brasil Fil: Preciado, Mercy. Instituto Nacional de Pesca; Ecuador Fil: Laaz, Enrique. Instituto Nacional de Pesca; Ecuador Fil: Mianzan, Hermes Walter. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto Nacional de Investigaciones y Desarrollo Pesquero; Argentina

From September 2004 to February 2005, 204 specimens of Etropus peruvianus were collected onboard exploratory fishing cruises in the eastern Gulf of California, caught in trawls at 276 m in depth. This finding exceeds the limit of vertical distribution (125 m) previously known for this species. Oceanographic conditions (such as temperature, salinity and dissolved oxygen), feeding and reproductive behavior determines the extension of the vertical distribution of E. peruvianus . Normal 0 false false false EN-US JA X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Tabla normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin-top:0cm; mso-para-margin-right:0cm; mso-para-margin-bottom:8.0pt; mso-para-margin-left:0cm; line-height:107%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin;}

Ten specimens of the dappled flounder Paralichthys woolmani were captured at a depths from 109 to 248.1 m in the central Gulf of California in an exploration cruise on board the research ship BIP XII in February 2005. The average temperature and dissolved oxygen concentration were 14.5°C and 1.01 mg O2 L-1, respectively. P. woolmani had not been reported at greater depth than 100 m. This new record represents an increase of 148.1 m in its bathymetric distribution in the Gulf of California.

Malformations of the Round stingray Urobatis hallerii, Cooper 1863 captured off the southwestern coast of Baja California Sur, Mexico are reported in this study. The ray was an adult male captured by artisanal fishery in the area of Estero Banderitas. Size measurements of total length and disk width were taken; the organism could be photographed when captured. Malformations of U. hallerii were found in the posterior part of the spine, a distortion in the upper part of the tail and in the left fin close to the tail. The specimen was considered able to reach the adult size usually reported in other specimens of this species despite the spine malformations because of its benthic habits and not losing its mobility completely. The observed malformations were likely due to genetic alterations although other studies are needed to see if other environmental factors could cause malformations in marine organisms mainly in fish and elasmobranchs.

The assemblage of the fish species obtained as bycatch in trawl nets on the Gulf of California in 2004, 2005 and 2007 was studied. Sampling was carried out during July and August at a series of stations along the coast of Sonora. The criteria for the most important fish species caught were drawn from abundance and frequency of occurrence and weight, using various ecological indices (index of relative abundance, biological value index and index of relative importance). After identification, these species and their abundances were used to define study groups based on similarity matrices and Ward's clustering method. We analysed 125 fish hauls containing>19,000 organisms, representing 243 species (fish, crustaceans, molluscs and echinoderms). There were 28 dominant species, most notably Urobatis halleri, Synodus scituliceps, Eucinostomus argenteus, Diplectrum pacificum and Haemulopsis nitidus. Cluster analysis, based on latitude, and bathymetry showed three station groupings. The first was character...

We report on the population dynamics of Dosidicus gigas off Guaymas from the 2002–2003 to 2007–2008 fishing seasons. The study was supported by the catch-at-length data of the commercial fleets. The results showed a large variation in recruitment because during some fishing seasons the recruitment was poor. This condition in the population may also be impacted by migration, a new distribution of jumbo squid in the eastern North Pacific, or the changes in the California current. We identified a pattern in the variability of recruitment. Warmer waters caused by the El Nino conditions in the California current are coincident with low recruitment. Cooler waters identified with negative anomalies in the sea surface temperature caused by La Nina were related to high recruitment. Our time-series showed a reduction in recruits and a fall in the mean biomass. For the jumbo squid fishery off Guaymas, recruitment determines trends of biomass over time. Our results also showed that for all fishing seasons the proportional escapement was between 59% and 89%, which was higher than the target level of 40%. Consequently, the harvest of jumbo squid is less than the optimum level.

We assayed genetic variations at five microsatellite loci of dolphinfish captured at five sites in 2005 and eight sites in 2006 to detect genetic population structure of dolphinfish Coryphaena hippurus in the Gulf of California and surrounding waters. Results show high genetic variation, similar to other pelagic fishes with large populations. Pairwise FST values and hierarchical AMOVA detected subtle but significant spatial and temporal heterogeneity, mainly in samples of 2005 and some of 2006. However, Bayesian assignment analysis failed to detect genetic differentiation, which was also supported by the Mantel test and gene flow estimates among the sampled sites. This suggests that, despite the slight heterogeneity detected in this region, the dolphinfish forms a single panmictic population with high genetic variation and gene flow.

The Gulf of California is unique because of its geographical location and conformation. It hosts diverse ecosystems and important fisheries that support industry and provide livelihood to coastal settlements. It is also the site of interests and

This paper reports on the population dynamics of Dosidicus gigas from the Gulf of California over the period of the 1995–1996 to 2001–2002 fishing seasons. Data were collected on mantle length, individual weight, and total catch. The D. gigas catches varied, with the lowest landings (1970 t) in the 1997–1998 fishing season and the highest (41,330 t) in 2001–2002. Mantle length ranged from 16 to 96 cm. The mantle length–mass relationship for all seasons showed allometric growth. Growth and natural mortality of D. gigas varied between seasons. The analysis of cohorts showed high interannual variability in annual fishing mortality, annual exploitation rate, recruitment, and mean abundance. The Thompson–Bell predictive model indicated that in some seasons the maximum sustainable yield could have been obtained with 30–50% of the current fishing mortality. However for other seasons the maximum sustainable yield could have been obtained with a current or greater fishing mortality. The fishing mortality associated with the maximum sustainable yield, FMSY, did not necessarily coincide with the fishing mortality associated with a level of proportional escape of spawning biomass, F%BR. The variability observed in this study is typical of squid populations but impossible to anticipate using the Thompson–Bell model. Consequently, auxiliary information (i.e. from research cruises) reflecting such variability in recruitment is needed to make accurate predictions and efficiently manage these resources. Extreme care should be taken in using these methods alone to predict future yields of D. gigas.

Spiny lobster (Panulirus argus), the most valuable fishery resource in Cuba, is subject to a state property regime and to a limited-access system. Managers need to be advised on the consequences of choosing different methods for managing the fishery. An age-structured bioeconomic model was developed to simulate the population dynamics of the stock allowing short-term and long-term (equilibrium) predictions on catch, biomass, egg production, revenue, cost and profit, due to changes in the fishing effort. The equilibrium version of the model can be used to estimate a number of bioeconomic reference points, such as the fishing effort for the maximum sustainable yield per recruit, or the maximum economic yield per recruit. The stochastic and dynamic version can be used to assess every year the risk of exceeding common benchmarks used in fishery management, taking into account uncertainty in parameters, such as catchability and recruitment. It was found that the recruitment has decreased since 1988 and that the effort should be limited at the level of maximum economic yield.

The shrimp fishery is one of the most important fishery in the Gulf of California. Blue shrimp Litopenaeus stylirostris (Stimpson, 1874) is the target species in the catch, in bays and coastal lagoons and represents about 30% of offshore fishing along the coast of the state of Sonora. We present growth estimates, reproductive periods, and size at first maturity for this species from samples conducted during three fishing seasons: 1993–1994, 1995–1996, and 1996–1997. Daily samplings of length, weight, sex, and sexual maturity were conducted from the catch of the fishing fleet of Sonora during the three seasons, as well as from bay catches in 1996–1997. A length-based method software (FiSAT) was used to assess growth, the longevity was calculated from Pauly's equation, and the maturity-length relationship was described with a logistic curve. The growth parameters obtained were: (i) females L ∞ (abdominal length in mm) 160 ≤ L ∞ ≤ 163 and K (1/year) 1.8 ≤ K ≤ 1.92; (ii) males 152 ≤ L ∞ ≤ 153 and 2.16 ≤ K ≤ 2.28; and (iii) for both sexes 159 ≤ L ∞ ≤ 160 and 1.9 ≤ K ≤ 2.04. The longevity estimated was 1.7 years. Reproduction occurred from March to September. The recruitment pattern, obtained through the ELEFAN II method, was from March to October, with a maximum from May to July. Size at first maturity was 109 mm (abdominal length). There were inter-annual variations in reproduction, as well as in the recruitment pattern.

We evaluated the interannual variation in the growth of brown shrimp Farfantepenaeus californiensis and the relation of this variation with sea surface temperature in the Gulf of California, Mexico. We used daily samplings of commercial captures at the packing plant at Guaymas, Sonora, Mexico from 1978 to 1994, samplings of commercial captures on board trawlers of the commercial fleet that operated along the coast of Sonora during the fishing seasons 1989–1995, and the monthly average of the sea surface temperature recorded by the oceanographic station of the Institute of Geophysics of the National University of Mexico, in Guaymas, Sonora from 1978 to 1995. The growth in the brown shrimp showed clear interannual variations. The relation between the temperature and the φ′and temperature and the growth coefficient K could be represented by a gaussian function that was significant (P

The rock shrimp (Sicyonia penicillata) from the Central Gulf of California is a secondary species to the penaeid shrimp fishery. Because of decreasing yields of penaeids, the importance of rock shrimp has been growing. Analysis of data taken on board fishing vessels suggests that this resource could be exploited from January to May, but the closed season for penaeid shrimp extends from May to September. This closed season is also coincident with low abundance of penaeids. In this contribution, we assess basic parameters of the population dynamics of S. penicillata and simulate possible exploitation scenarios of rock shrimp involving some changes in the fishing season and an increase in fishing mortality. The results show that S. penicillata has a slow growth (K/year=1.25, abdominal length, L∞=104 mm), with a natural mortality of M/year=2.48 and continuous recruitment, with a maximum during August–October. Fishing mortality-at-length showed an exploitation pattern where higher F values corresponding to individuals 8–9 months, the average fishing mortality and average exploitation rates were F=1.58/year and F/Z=0.36/year.

[Interannual changes in the reproductive pattern of the brown shrimp, Farfantepenaeus californiensis, a commercially important marine crustacean, were analysed as a function of sea water temperature. Daily samples of gravid females from 1979 through 1994 and monthly sea water temperatures were examined. The results show a high interannual variability of the reproductive period with two patterns; one in which spawning occurs throughout the year, the other with two peaks of mass spawning. The first of the two peaks is the more intense, occurring from March to May; the other is in October and November and is less intense. The extended spawning period occurs under warmer conditions and is probably associated with El Nino events. The pattern with two peaks is associated with average sea water temperatures. Occurrence of one pattern or the other may have significant consequences for managing this fishery. Los cambios interanuales en el patron reproductivo del camaron cafe Farfantepenaeus californiensis, un crustaceo escencialmente marino, fueron analizados en funcion de la temperatura del agua de mar. Se analizaron muestreos diarios de hembras ovigeras y temperatura promedio mensual del agua de mar desde 1979 a 1994. Los resultados muestran, una alta variabilidad interanual del periodo reproductivo con dos patrones: uno en el que el desove se efectua a todo lo largo del ano y otro con dos periodos masivos de reproduccion. El primero de ellos siendo el mas intenso y presentandose durante marzo a mayo, el segundo es menos intenso y ocurre de octubre a noviembre. La extension del periodo reproductivo ocurre cuando se presentan condiciones calidas y es probable que este asociado a eventos El Nino. El patron con dos periodos de reproduccion masiva se observo principalmente bajo condiciones promedio. La ocurrencia de uno y otro patron puede tener consecuencias importantes para el manejo de la pesqueria., Interannual changes in the reproductive pattern of the brown shrimp, Farfantepenaeus californiensis, a commercially important marine crustacean, were analysed as a function of sea water temperature. Daily samples of gravid females from 1979 through 1994 and monthly sea water temperatures were examined. The results show a high interannual variability of the reproductive period with two patterns; one in which spawning occurs throughout the year, the other with two peaks of mass spawning. The first of the two peaks is the more intense, occurring from March to May; the other is in October and November and is less intense. The extended spawning period occurs under warmer conditions and is probably associated with El Nino events. The pattern with two peaks is associated with average sea water temperatures. Occurrence of one pattern or the other may have significant consequences for managing this fishery. Los cambios interanuales en el patron reproductivo del camaron cafe Farfantepenaeus californiensis, un crustaceo escencialmente marino, fueron analizados en funcion de la temperatura del agua de mar. Se analizaron muestreos diarios de hembras ovigeras y temperatura promedio mensual del agua de mar desde 1979 a 1994. Los resultados muestran, una alta variabilidad interanual del periodo reproductivo con dos patrones: uno en el que el desove se efectua a todo lo largo del ano y otro con dos periodos masivos de reproduccion. El primero de ellos siendo el mas intenso y presentandose durante marzo a mayo, el segundo es menos intenso y ocurre de octubre a noviembre. La extension del periodo reproductivo ocurre cuando se presentan condiciones calidas y es probable que este asociado a eventos El Nino. El patron con dos periodos de reproduccion masiva se observo principalmente bajo condiciones promedio. La ocurrencia de uno y otro patron puede tener consecuencias importantes para el manejo de la pesqueria.]

The length–weight relationship parameters were recorded for 24 families, 34 genera and 46 species of 10 963 specimens sampled off the western coast of Baja California Sur, Mexico, many for the first time. New maximum length records were obtained for seven of these species. The b values ranged from 2.62 for Sebastes rubrivinctus to 3.80 for Peprilus simillimus.

We present the results of the analysis of overlap in the diet of the Pacific sardine Sardinops caeruleus, the northern anchovy Engraulis mordax and the thread herring Opisthonema libertate. These are the most commercially important species of small pelagic fishes in the fishery that is developed in the Gulf of California. Although the diet of these species is very similar, the overlap is only significant between the northern anchovy and the thread herring. As these two species do not overlap spatially in the Gulf of California, the possibility of competition for food between them is considered unlikely.

Catch-at-size data were analyzed for Farfantepenaeus californiensis from fishing seasons 1978/1979 to 1994/1995. The catch-at-size model could be fitted to the catch-at-size data for the different fishing seasons. It was observed that the recruitment to the fishery changed suddenly during the study period, and the recruitment to the fishery may occur over a range of length classes. The recruits were defined as size classes less than 93.5mmin abdominal length. Recruitment varied from 200–3,800 million recruits. In contrast, the size classes were larger than 93.5 mm in terms of abdominal length, and the number of adults varied from 3,500,000–50,000,000. In the study zone, it was not common to find remnant biomass of adults. Consequently, the most abundant size intervals of abdominal length were 62.4 mm, 67 mm, and 72.2 mm. The results of the harvest rate-at-size showed that the size interval from 65–80mmin abdominal length was less than 0.05. The highest levels of harvest rate-at-size were estimate...

We analyzed the catch and effort data for the brown shrimp (Farfantepenaeus californiensis) fishery over 22 years. We used a biomass dynamic model in a stochastic version to analyze the catch-per-unit effort of the trawl fishery in the Gulf of California, Mexico. Two hypotheses were proposed: the first (observation error) assumes that the catch-per-unit effort (CPUE) is measured with error, while in the second (process error), the variability of the population is produced by factors not included in the model. The results show that the hypothesis of the process error was accepted. In this case, the hypothesis of the process error recognizes several sources of perturbation in the model. For example, changes in the size structure of the shrimp population, changes in the natural mortality, variations in the fecundity or recruitment, and changes in the environment. Evidence of the relation between the environment and the shrimp population is discussed, as is the possibility of proposing a biological hypothesis for the trends of the population and the CPUE.