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Swordfish are migratory fish that inhabit tropical to temperate waters, but little is known about movement patterns or mixing between subpopulations of this species. This study examines carbon (δ13C) and nitrogen (δ15N) stable isotope ratios in growth rings of the anal fin spine and muscle tissue of swordfish from 3 different areas of the Eastern North Pacific Ocean (ENPO)—off Baja California Sur (Mexico) and California (USA), and in the North Pacific Subtropical Gyre (NPSG)—to assess swordfish movements between these areas. The analysis of δ13C and δ15N revealed no relationship between fish size and δ15N, suggesting a consistent consumption of prey items by this species over time. Differences between the anal fin spine and muscle were found, but interpreting these isotopic differences requires information on tissue-specific isotope turnover rates. The spatial pattern suggests that swordfish populations from these areas in the ENPO exhibit a relatively unexpected homing behavior at the temporal scale, according to anal spine and muscle turnover rates. Our findings support that swordfish may show site fidelity, which has important implications for their management and stock assessments.

Capture‐based aquaculture (CBA) is a strategy to capture wild aquatic organisms for rearing. The most iconic species produced under this scheme are bluefin tunas. In Mexico, CBA of this species is developed with Pacific bluefin tunas (PBFT). The parametrization of a biological production function able to describe biomass dynamics during the production cycle is one of the strategies that can help optimize production. The objective of this study was to explain biomass dynamics in capture‐based Pacific Bluefin tuna aquaculture in Mexican waters through parameterization of a growth and survival model. This study also assessed the impact of uncertain intrinsic CBA variables (i.e. seed weight, number of stocked individuals and sea surface temperature [SST] variability). The model was parameterized with production records of 47 net pens in two production sites (an offshore and an inshore facility) during three cycles. The results suggested that production performance was related to SST given that this factor affected survival, mainly during the first ≈40 days after stocking. The risk analysis showed that stocking during the second half of the fishing season from June to August increased the likelihood of matching or exceeding the Key Performance Indicator (KPI) defined regarding biomass increase per pen.

Ovaries of bluefin tuna, Thunnus thynnus, from organisms measuring 247.62 ± 3.54 cm fork length collected within the Mexican Exclusive Economic Zone in the Gulf of Mexico, were examined. Th...

Isotopic niche and resource partitioning were examined between striped marlin (Kajikia audax) and swordfish (Xiphias gladius) using stable isotope ratios from spine bone and muscle samples....

Background The dolphinfish, Coryphaena hippurus, is a fast-swimming, predatory fish exhibiting relatively fast growth and early maturation among marine teleosts. It is an important, potentially renewable resource throughout its global subtropical-to-tropical range. Understanding the ecology of this wide-ranging fish is critical to proper fisheries management, but studies have historically depended heavily upon aggregated catch data reported by fisheries. This study uses tagging data to explore finer scale dolphinfish movements in two subregions of the Eastern Pacific Ocean (EPO)—the west coasts of Baja California Peninsula (WBC) and Oaxaca (OAX), Mexico. Results Adult dolphinfish (fork length 66–129 cm) were tagged with conventional (n = 132 tags) and electronic tags (n = 30 tags, miniPAT) between 2010 and 2014. Recapture rate of conventional tags was 4.5% with a maximum days of liberty of 141 days (mean = 56 d); 20 electronic tags reported but all did so prior to programmed release dates, with days at liberty ranging from 4 to 62 (mean = 24 d). Fish remained within the region they were tagged except for six fish tagged in WBC and one in OAX. Latitudinal (WBC) and longitudinal (OAX) extensions of observed fish movements (determined via a novel analytical approach) increased with days at liberty. Despite occasional deep dives (max 262 m), fish remained surface oriented with short excursions below the isothermal layer but larger OAX fish (fork length [103 cm, 120 cm]) inhabiting warmer waters (sea surface temperatures (SST) > ~ 26 °C) spent more time below the isothermal layer than smaller fish (fork length [90 cm, 112 cm]) inhabiting colder WBC surface waters (SST > ~ 22 °C). Conclusions This study reveals movements of dolphinfish that infer regional differences in thermal habitat utilization and displacement over time. This inference evokes questions important to fisheries management regarding the three-dimensional extent of the dolphinfish’s realized thermal niche, its population structure, and the spatiotemporal connectivity of its habitats within the multinational EPO. With improved tag retention, longer deployments should capture increasing displacements along observed axes (N/S vs. E/W); the orientation of seasonal displacement axes suggest longer-distance movements would provide opportunities for reproductive mixing via trans-national migrations.

El objetivo de esta investigación fue describir por primera vez al copépodo ectoparásito en la piel del atún aleta amarilla Thunnus albacares (Bonnaterre, 1788) en el estado de Sinaloa en las costas del Pacífico mexicano. Se identificaron cinco copépodos Pennella filosa L. (Copepoda: Pennellidae), los miembros de este género se caracterizan por la forma, el tamaño y la longitud del parásito, el tipo de hospedero, la disposición de las papilas cefalotorácicas, la segmentación de la primera y la segunda antena, y la estructura de las plumas abdominales. Este estudio es significativo porque es la primera vez que se describe este copépodo de la familia Pennelidae que parasita al atún Thunnus albacares, que es considerado una especie de pez de gran valor que se captura todo el año tanto por la pesca costera comercial como por la pesca recreativa en Sinaloa. México. Aunque existen varios informes en todo el mundo, localmente es una nueva área de distribución geográfica para este copépodo y, por lo tanto, contribuye a nuestra comprensión de la Biología, la biodiversidad y la preferencia de hospedadores de estos parásitos.

With the aim to expand the understanding of the feeding ecology of the swordfish, two supplementary techniques were used: analysis of stomach contents, including 244 samples; and analysis of stable carbon (δ13C) and nitrogen (δ15N) isotopes, with 128 samples of muscle tissues from animals collected in the western coast of Baja California. Samples were obtained from swordfish captured by the longline fleet that operates along the western coast of Baja California peninsula. Thirty-three different prey types were identified through the analysis of stomach contents. Based on the index of relative importance (IRI), cephalopods accounted for 98.91%, fish 0.88%, and pelagic crustaceans 0.21%. The stable isotope analysis showed δ15N values between 13.05‰ and 19.66‰, and δ13C values between − 19.32‰ and − 15.60‰, indicating that the swordfish feeds primarily on oceanic species. The stable isotope mixing model (SIAR) established that prey species that most contribute to the diet of Xiphias gladius were cephalopods, followed by the crustacean Pleuroncodes planipes, and the fish Lagocephalus lagocephalus. The SIBER test corroborates similar diets between sexes and sex-maturity groups, indicating that all swordfish analyzed essentially occupied the same trophic niche.

Determining what animals eat is simultaneously challenging and yet also critical for ecologists, fisheries scientists, and resource managers. The tools of trophic ecology have expanded considerably in the last half century in pursuit of this goal. In this study, we combined stomach contents, stable isotope, and fatty acid analyses to investigate trophic patterns in three species of highly mobile, pelagic predators: striped marlin (Kajikia audax), blue marlin (Makaira nigricans), and common dolphinfish (Coryphaena hippurus). We were particularly interested in examining individual diet specialization among these species. We compared the short-term stomach contents with long-term diet proportions estimated from stable isotope ratios and fatty acid profiles using a Bayesian mixing model. Our results indicate that all three species feed on a mix of prey types. This work furthermore suggests that individuals of all three predator species demonstrate generalist feeding habits, with minimal differences in long-term (weeks, months) diet estimates between individuals with different short-term (hours, days) stomach contents. This novel, three-part analytical approach can elucidate complex and otherwise elusive trophic dynamics.

Length-weight relationships (LWRs) were estimated for Pacific blue marlin ( Makaira nigricans ), striped marlin ( Kajikia audax ), sailfish ( Istiophorus platypterus ), dolphinfish ( Coryphaena hippurus ) and yellowfin tuna ( Thunnus albacares ). These five fish species are key top predators of the pelagic ecosystem and are economically important resources in the sport fishing of Baja California Sur, Mexico. Overall, 53,359 length and weight records were analyzed for the period 1990-2015. LWRs were significant ( P < 0.05), with b -values ranging from 2.52 to 3.13.

The roosterfish is a coastal pelagic species that inhabits shallow waters of the Eastern Pacific Ocean. Despite its ecological and economic importance within the region, there are few studies on its basic biology, especially those focused on age and individual growth. Therefore, the objective of this study was to estimate roosterfish age and individual growth parameters through counting growth increments of sagittal otoliths. The work focused on organisms caught off Baja California Sur, Mexico (BCS) by both the sport and artisanal fishing fleets from 2010–2017. A total of 266 organisms were sampled during the study period, ranging in size from 5.2–133 cm fork length. A model was generated to describe the relationship between otolith radius (OR) and fork length (FL) of the fish, where FL = -43.3 + 44.59 OR. The periodicity of otolith growth increment formation was annual, and this study found roosterfish age estimates to range from 0 to 8 years old, with most individuals ranging from 1–2 years of age. Based on the fitting of the data to three individual growth models (Gompertz, Logistic and von Bertalanffy, VBGF), the VBGF best fit the individual growth curve for roosterfish. The VBGF parameter of L ∞ = 131.53, k = 0.35 y t 0 = -0.23 supports previous studies and suggests that roosterfish are very fast growing in the first years of life.

With the aim of determining the benefit from consumption of dolphinfish Coryphaena hippurus from La Paz and Cabo San Lucas in the southern area of the Gulf of California, mercury (Hg) and selenium (Se) were measured in liver and muscle of specimens (n = 362) collected between 2006 and 2013. Mean levels of Hg in muscle (0.61 μg g-1) and liver (0.42 μg g-1) of all individuals from La Paz were significantly higher (p < 0.05) than in fish from Cabo San Lucas; in the case of Se, mean concentrations in liver (1.54 μg g-1) of all individuals from La Paz were significantly higher (p < 0.05) than in fish from Cabo San Lucas. Hg levels in muscle were positively and significantly (p < 0.05) correlated with fork length and weight of fish; in liver, Hg and Se were significantly (p < 0.05) correlated with fork length and weight of specimens. Levels of Hg and Se in muscle and liver among years varied significantly (p < 0.05); although there was not a defined pattern of temporal fluctuations for both elements, the lowest Hg levels occurred in 2009 when surface water temperatures were the highest for the sampled years. With respect to the Se health benefit value (HBVSe), results were positive and above the unit in all cases; it implies that consumption of dolphinfish in the southern Gulf of California is beneficial.

Oceanic mesoscale events such as eddies, coastal upwelling, filaments and fronts created by water mass intrusion present properties allowing them to concentrate, transport and disperse salt, nutrients and plankton, among other important constituents in the ocean. The use of satellite images enables the continuous monitoring of the ocean dynamics at different temporal and spatial scales, aiding the study of its variability. This study focuses on the identification of these mesoscale events in the Gulf of California (GC) by means of sea surface temperature (SST) and chlorophyll a (Chl a) fronts (edge) detection by processing 5-day satellite images from the 1998–2019 period. The annual occurrence or frequency and duration of each event was identified; the interannual variability was evaluated and underlying correlations with the Multivariate El Niño Index (MEI) and the Pacific Decadal Index (PDOI) were assessed via Principal Component Analysis. Most events showed a seasonal variability due to the seasonal behavior of forcing agents (i.e., Pacific Ocean and winds) that stimulate their formation or presence in the GC; seasonality was more evident in the northern region than in the southern region. The interannual variability of their frequency or duration was associated with strong and intense El Niño and La Niña conditions (positive or negative MEI values) together with positive or negative phases of the PDOI. The use of SST and Chl a satellite images with a 5-day temporal resolution allowed to better identify and quantify the annual frequency and duration of each mesoscale event. It allowed to detect a seasonal behavior of these events in the northern region, followed by the central region. The southern region, due to the interaction of different water masses with unique characteristics, exhibited a less evident seasonality in the frequency of eddies, and no apparent association between their interannual frequency and duration with the MEI and PDOI. Constantly monitoring these oceanic events and their variability will help in the understanding of how the different regions of this large marine ecosystem respond to these variations in the long term.

With the aim of knowing annual variations of Hg concentrations in muscle and liver of blue marlin (Makaira nigricans) from the southern Gulf of California, fish were collected between 2005 and 2012 in three areas. In general, Hg levels were more elevated in liver than in muscle. Variations of Hg concentrations in muscle and liver among the studied years were not significant. Hg levels in muscle and liver increased significantly with length and weight of fish. In comparison to other studies, Hg levels in muscle and liver were lower. With respect to maximum permissible limits (1.0 µg g−1 wet weight) of Hg in Mexico, the average concentration (1.91 µg g−1 wet weight) in the edible portion (muscle) of blue marlin was over the legal limit; this issue is worth research efforts in relation to the rate of ingestion of this species and the co-occurrence of selenium in the edible portion.

Objective: To study how temperature, serum, and gonadotropin supplementation affect the organotypic culture of human immature testicular tissue (ITT) in vitro. Design: Experimental basic science study. Setting: Reproductive biology laboratory. Patient(s): ITT from 4 boys with cancer that had testicular tissue cryopreserved as part of their fertility preservation treatment. Intervention(s): In vitro organotypic culture of ITT, exposed to different temperatures (37 degrees C vs. 34 degrees C), serum (fetal bovine serum [FBS] vs. Knockout Serum Replacement [KOS]), and gonadotropin supplementation (with and without FSH and LH). Main Outcome Measure(s): Characterization of the tissue was performed at days 0, 14, and 70 with the use of reverse-transcription quantitative polymerase chain reaction, terminal deoxynucleotide transferase-mediated dUTP nick-end labeling, histologic analysis by means of hematoxylin-eosin staining, and immunohistochemical staining. Hormonal secretion was determined at days 3, 14, 28, and 70 by means of immunofluorescent assay. Result(s): The 37 degrees C conditions showed an accelerated loss of tubular morphology and higher intratubular apoptosis. KOS supplementation triggered the up-regulation of STAR, SOX9, DAZL, DDX4, PLZF, and UTF1, the percentage of SOX9+/androgen receptor (AR)-positive mature Sertoli cells at day 14, and testosterone secretion. Gonadotropin supplementation increased the numbers of both undifferentiated UTF1+ spermatogonia and premeiotic VASA+/SYCP3+ spermatogonia at day 14, and the number of SOX9+ Sertoli cells at day 70. The low SOX9+/AR+ colocalization, the disorganized pattern of ZO-1, and the progressive decrease of antimullerian hormone secretion indicated inefficient Sertoli cell maturation in vitro. Conclusion(s): The 34 degrees C condition in KOS showed the best results for the survival of both spermatogonia and Sertoli cells. FSH/LH supplementation also improved long-term survival of Sertoli cells and the maturation of spermatogonia up to meiotic initiation in short-term culture. (C) 2018 by American Society for Reproductive Medicine.

Background The assembly and annotation of a genome is a valuable resource for a species, with applications ranging from conservation genomics to gene discovery. Genomic resource development is especially important for species in culture, such as the California Yellowtail (Seriola dorsalis), the likely candidate for the establishment of commercial offshore aquaculture production in southern California. Genomic resource development for this species will improve the understanding of sex and other phenotypic traits, and allow for rapid increases in genetic improvement for and economic gain in culture production. Results We describe the assembly and annotation of the S. dorsalis genome, and present resequencing data from 45 male and 45 female wild-caught S. dorsalis used to identify a sex-determining region and marker in this species. The genome assembly captured approximately 93% of the total 685 MB genome with an average coverage depth of 180×. Using the assembled genome, resequencing data from the 90 fish were aligned to place boundaries on the sex-determining region. Sex-specific markers were developed based on a female-specific, 61 nucleotide deletion identified in that region. We hypothesize that Estradiol 17-beta-dehydrogenase is the putative sex-determining gene and propose a plausible genetic mechanism for ZW sex determination in S. dorsalis involving a female-specific deletion of a transcription factor binding motif that may be targeted by Sox3. Conclusions Understanding the mechanism of sex determination and development of assays to determine sex is critical both for management of wild fisheries and for development of efficient and sustainable aquaculture practices. In addition, this genome assembly for S. dorsalis will be a substantial resource for a variety of future research applications. Electronic supplementary material The online version of this article (10.1186/s12864-017-4403-1) contains supplementary material, which is available to authorized users.

The striped marlin is the primary target of the sport fishery operating out of Cabo San Lucas, Baja California Sur, Mexico. Recreational fishery log books indicated that striped marlin constitute approximately 80% of annual billfish catches by the local sport fishing fleet. Generalized additive models were used to identify major environmental factors that affect the distribution of striped marlin where the recreational fishery operates. For statistical modeling, the nominal catch rate (number of fish per trip) was used as the response variable and environmental, spatial, and temporal variables were used as the predictor variables. Exceptionally high catch rates were recorded in late 2008 and early 2009 (>5 striped marlin per trip), which followed observations of high concentrations of chlorophyll- a during the previous six months. Seasonal variations with greater catch rates during the late fall and winter were found. The best model showed that high catch rate of striped marlin occurs when warm temperatures (26–28 °C), high chlorophyll- a concentration (>1 mg m −3 ), and negative values of PDO index (

Dolphinfish (Mahimahi) are a high-demand resource for sport and coastal fisheries, mainly in the Pacific Ocean. Due to their economic and ecological importance, studies of their biology are very important to understand their function in ecosystems. We used stable isotope and stomach content analyses to determine the most important prey of the common dolphinfish, as well as the trophic level of this species in two areas of the southern Gulf of California. Stomach contents of 445 specimens were analysed. Using both techniques, we found that the most important prey for dolphinfish in the southern Gulf of California were three invertebrate species followed by fish. This contrasts with results from other authors who found that this species was mainly piscivorous in other locations. Stomach content analysis indicated differences in prey biomass by area, season and size class. The isotopic analysis did not show significant differences between seasons or sexes. Both stomach contents and stable isotope analyses showed that although this predator consumed a wide prey spectrum, only a few prey items made up the bulk of the diet, which resulted in a low SD in δ15N values and low Levin's index values. We conclude that this fish is an opportunistic predator that may consume a wide prey spectrum, but that it mainly consumes prey that are abundant in the area, such as crustaceans and cephalopods in the Gulf of California.

Using data from analyses of stomach contents and stable isotopes, we examined high-resolution variations in the feeding habits and trophic position of Dolphinfish Coryphaena hippurus during 2005–2007. In total, 418 specimens were collected off the southern Baja California peninsula, Mexico. Based on analysis of stomach contents (% index of relative importance [%IRI]), Dolphinfish consumed mainly epipelagic prey, with the red crab Pleuroncodes planipes as the most abundant prey species. The diet was highly similar between sexes but differed between size-classes: Dolphinfish smaller than 65 cm FL fed mainly on Pacific Sardine Sardinops sagax caeruleus (%IRI = 30), whereas those larger than 110 cm FL fed mainly on jumbo squid Dosidicus gigas (%IRI = 45) in addition to red crabs. Dietary differences between the smallest and largest specimens were mainly related to changes in morphology and spatial stratification by size (i.e., to avoid cannibalism). Trophic positions estimated by both methods indicate...

Decades of billfish tagging studies have been hindered by below-par conventional tag recovery rates and high rates of premature satellite pop-up tag shedding. With hopes of obtaining long-term tracking data, we performed the world’s first archival tagging study on an istiophorid, surgically implanting 99 archival tags into the peritoneal cavity of striped marlin (Kajikia audax) off the coast of Baja California, Mexico. Marlin were also tagged externally with a conventional tag before release. Ten archival tags (10.1%) were recovered with days at liberty (DAL) ranging from 400 to 2795. Nine recoveries were from Mexican waters, whereas one marlin was recaptured off Ecuador. In total, 100% of the light stalks on the archival tags failed, with nine failing within the first 3 months of deployment; because the light data are used to estimate the geographic position of the tagged fish, tracking data were compromised. The absence of conventional tags on all recaptured marlin indicates that studies of marlin using conventional tags have been hindered by tag shedding rather than tagging-associated mortality or underreporting. Our high recapture rate and long DAL suggest istiophorid science could be greatly advanced by archival tagging if new tag designs or methods can eliminate tag failure.

"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."

Stable isotope values of Kajikia audax (Philippi, 1887) and Makaira nigricans (Lacepede, 1802) were analyzed to detect differences associated with trophic segregation influenced by their feeding habits in the southern Gulf of California, Mexico. We sampled the dorsal white muscle of 47 M. nigricans and 35 K. audax collected from 2005 to 2007. No relationship was found between billfish body size and isotopic values. Significant differences in (delta connection)15N and (delta connection)13C values were found among genders, years, or areas for K. audax. The significant differences in (delta connection)15N and (delta connection)13C values found between areas for M. nigricans suggested differences in foraging preferences or movement patterns. Significant differences were also found in (delta connection)15N and (delta connection)13C values between K. audax and M. nigricans, possibly placing these two billfish species at different trophic levels. These patterns appear to correspond to each species' known foraging ecology and suggest that these two billfishes have different trophic preferences or migratory histories.

International audience; Global population genetic structure of yellowfin tuna (Thunnus albacares) is still poorly understood despite its relevance for the tuna fishery industry. Low levels of genetic differentiation among oceans speak in favour of the existence of a single panmictic population worldwide of this highly migratory fish. However, recent studies indicated genetic structuring at a much smaller geographic scales than previously considered, pointing out that YFT population genetic structure has not been properly assessed so far. In this study, we demonstrated for the first time, the utility of 2b-RAD genotyping technique for investigating population genetic diversity and differentiation in high gene-flow species. Running de novo pipeline in Stacks, a total of 6772 high-quality genome-wide SNPs were identified across Atlantic, Indian and Pacific population samples representing all major distribution areas. Preliminary analyses showed shallow but significant population structure among oceans (FST=0.0273; P-value

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 (

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.

Management of highly migratory fish species is generally assumed to require complicated international agreements. The effects of spatial closures for such species are thought to be diluted by their extensive movements. We tested these assumptions using a case study of striped marlin (Kajikia audax) fisheries off of Baja California, Mexico. Beginning in 1977, Mexico instituted a series of long-line fishery closures and closed areas to reduce commercial fishing mortality rates on billfishes. Using data from the Japanese long-line fishery and the recreational billfish fishery in a stock reduction analysis (SRA) model, we show that temporary closures of Mexico’s EEZ to long-lining from 1977–1980 and 1984–1985 had a rapid effect on local abundance of striped marlin. Regional striped marlin abundance likely increased by 12–22% following the 4-year closure and 6–12% following the 2-year closure. Increases near Baja California may have been larger. Recreational catch-and-release appears to have a more modest effect because catches in the recreational fishery are substantially smaller than historic long-line catches. A 100% release rate over the 10-year period for which recreational catch data were available would likely have increased regional abundance by 2.8–7.5% relative to no recreational release. There is also evidence for a small effect of the El Nino Southern Oscillation (ENSO) on recruitment or net immigration, with stronger recruitment or net immigration during the cooler La Nina phase.

In the eastern Pacific Ocean (EPO), dolphinfish (Coryphaena spp.) are caught incidentally by the tuna purse-seine fishery; therefore, the records of this fishery are a good source of information to analyze the distribution of dolphinfish. To determine the spatiotemporal distribution of dolphinfish and catch variability in the three types of tuna-fishing sets (on schools associated with dolphins or with floating objects, or on unassociated schools), statistical analyses were made of the 1998–2005 records taken by scientific observers on board tuna-fishing vessels. The incidental catch did not show a well-defined annual or seasonal distribution pattern. Two high catch areas were observed, the first located in Mexican offshore waters (15–25°N), with 15% of the total catch, and the second located in offshore waters of the central EPO (0–10°N), with almost 60% of the total catch. The incidental catch was significantly different among years and seasons (H7,780 = 54.6, p

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

Los patrones de estructura genetica en las poblaciones marinas estan asociados a una variedad de mecanismos de dispersion y de escalas espaciales. Las especies pelagicas migratorias, como el dorado Coryphaena hippurus, reafirman la nocion de un medio ambiente marino abierto y continuo. Muchos estudios han mostrado que las especies pelagicas oceanicas tienden a ser homogeneas geneticamente a grandes escalas geograficas, solo existiendo diferenciacion entre sus limites de distribucion o entre cuencas oceanicas. En este trabajo presentamos resultados que indican heterogeneidad genetica del dorado a escalas geograficas menores a las predichas por las generalizaciones anteriores. Patrones de restriccion (RFLPs) del gen mitocondrial NADH1 produjeron niveles de estructura genetica altamente significativos (ΦST = 0.029, P = 0.004, AMOVA) entre peces de Baja California Sur (BCS), Sinaloa y Hawai, consistentes con frecuencias haplotipicas heterogeneas (P = 0.014, prueba exacta de diferenciacion genetica) y con una menor diversidad molecular en los peces muestreados en BCS Patterns of genetic structure among marine populations involve a variety of dispersal mechanisms and spatial scales. Pelagic species, such as the dolphinfish Coryphaena hippurus, epitomize the open and continuous nature of the marine environment due to their extensive migrations. Many studies have revealed that oceanic pelagic species tend to be genetically homogeneous over local and often extended geographic scales and only show levels of differentiation among extreme localities or ocean basins. Here we present genetic data suggesting genetic heterogeneity in the dolphinfish at geographic scales much smaller than those predicted by those generalizations. Mitochondrial NADH1 gene RFLPs revealed a highly significant (ΦST = 0.029, P = 0.004, AMOVA) molecular genetic structure among fish from Baja California Sur (BCS), Sinaloa and Hawaii, consistent with heterogeneous haplotype frequencies (P = 0.014, exact test of genetic differentiation) and a depressed molecular diversity in fish sampled off BCS.

Catch data of the yellowfin tuna (YFT) fishery were used to study the relationship between the seasonal and spatial variations of YFT with or without the presence of mesoscale structures at the entrance to the Gulf of California (19º–24º N, 104º–112º W). The YFT catches were distributed mainly over the continental shelf and around islands and seamounts. High concentration sets of YFT occurred throughout the year around the Marías islands and Cabo Corrientes, particularly in March and June. A warm (>28ºC) coastal jet with a width of 1.5 Rossby radius (~20.6 km) was observed off Cabo Corrientes during February and April, covering all the continental shelf off Cabo Corrientes. The jet moved at an average speed of 0.31 m s–1 and extended northwards to the Roca Corbetera seamount. The interaction with cooler water generated a frontal zone around which the YFT catches were concentrated. In contrast, during March the wind field was more favorable for the development of coastal upwelling off Cabo Corrientes. We observed an upwelling region with sea surface temperature of 18ºC and an offshore width of about a 3.7 Rossby radius of cold water that covered some 2600 km2. The YFT catches occurred in warmer water north of the upwelling zone.

Laguna Ojo de Liebre is part of El Vizcaino 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 Datil 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. Palabras clave: Tendencias espaciales, Laguna Ojo de Liebre, Nyctiphanes simplex, Seaweed, spatial, seasonal

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.

To determine the spatial and seasonal variation of the catch-per-unit-effort of the skipjack tuna as an index of abundance, the logbook records of the international purse-seine tuna fleet that operated in the Eastern Pacific Ocean during 1970–1995 were used. Data were provided by the Inter-American Tropical Tuna Commission (IATTC). The catch-per-standard-day fishing (CPSDF), by year, quarter, and type of indicator was estimated for the operational area. The interannual and seasonal variation were significant, with two long periods in the fishing yields (1970–1982 and 1983–1995). In the first period, the highest yield was 1971 and the lowest in 1982. In the second period, the highest yield was in 1995, and the lowest 1983. Seasonally, the highest yields were obtained in the first half of the year, and the lowest during the third quarter. As result of the CPSDF distribution, the most productive areas are south of 10°N and east of 135°W.

An analysis of the catch associated with floating objects by the Mexican tuna purse‐seine fleet in the eastern Pacific Ocean during 1992–1993 was made to determine the spatial and seasonal distribution. The information used was generated by observers of the Programa Nacional de Aprovechamiento del Atun y Proteccion a los Delfines (PNAAPD). There was no clear seasonal and spatial distribution of floating objects examined in this study, however there were areas where floating objects were more common; the mouth of the Gulf of California, waters offshore Peru, and in oceanic waters. The largest catch of yellowfin tuna was offshore of Peru in winter. Two areas with largest (length) yellowfin tuna were the mouth of the Gulf of California and offshore Peru. For skipjack tuna, the largest catch was offshore Peru in winter, but the largest skipjack were caught between 120° and 130°W along 10°N in spring. The largest yellowfin tuna were captured by sets on bamboo, fish aggregating devices (FADs), planks and boards...

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 Nino 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 LaNina, 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 Nino.

The depth distribution and temperature preferences of wahoo (Acanthocybium solandri) were quantified in the eastern North Pacific using archival tags. One hundred and eight data-loggers were deployed on wahoo (105–165-cm fork length) from 2005 to 2008 at three locations off of the coast of Baja California Sur, Mexico (Alijos Rocks, 25°00′N/115°45′W; Magdalena Bay Ridge, 25°55′N/113°21′W; Hurricane Bank, 16°51′N/117°29′W). Twenty-five tagged individuals (23%) were recaptured within close proximity (

Regional ecological patterns, distribution and population structure of Prionace glauca were analyzed based on samples collected on-board two long-line fleets operating in oceanic waters (1994-96/2000-02) and in coastal oceanic waters (2003-2009) of the eastern tropical Pacific off México. Generalized additive models were applied to catch per unit of effort data to evaluate the effect of spatial, temporal and environmental factors on the horizontal distribution of the life stages (juvenile, adult) and the sexes at the estimated depth of catch. The presence of breeding areas was explored. The population structure was characterized by the presence of juveniles' aggregations and pregnant females towards coastal waters and the presence of adult males' aggregations towards oceanic waters. The species exhibited horizontal segregation by sex-size and vertical segregation by sex. Distribution of the sex-size groups at oceanic waters was seasonally affected by the latitude; however, at coastal oceanic waters mainly females were influenced by the longitude. Latitudinal changes on the horizontal distribution were coupled to the seasonal forward and backward of water masses through the study area. Adult males showed positive relationship with high temperatures and high-salinities waters (17.0°-20.0 °C; 34.2-34.4) although they were also detected in low-salinities waters. The distribution of juvenile males mainly occurred beyond low temperatures and low-salinities waters (14.0°-15.0 °C; 33.6-34.1), suggesting a wide tolerance of adult males to explore subartic and subtropical waters. At oceanic areas, adult females were aggregated towards latitudes25.0°N, mainly associated to subtropical waters during summer. The distribution of juvenile females indicated its preference by lower temperatures and more saline waters. Presence of pregnant females suggests that the eastern tropical Pacific off México represents an ecological key region to the reproductive cycle of P. glauca.

Dolphinfish (Coryphaena hippurus) is found in tropical and subtropical waters, and is an important sport and commercial species. The migrations of this species are associated with sea surface temperature changes and therefore climatic events such as an El Ni ˜no have an effect on its distribution in the PacificOcean. Our objectives were to determine the seasonal and interannual variations in catch rate and to correlate these with sea surface temperature. The database used in this study was the catch rate (number of organisms/trip) made by the recreational fleet that operated in Cabo San Lucas, B.C.S. from 1990 to 2000. To identify trends that may exist due to fluctuations in tourism, which could generate a bias in the use of the catch rates as relative indices of abundance, we analysed the daily data base of the effort (number of trips) that were recorded by the harbor authorities. Significant differences were found in the monthly average of effort during summer–autumn, which is the hurricane season in this area. The monthly average stayed above 1700 trips. Although interannual variation was not significant (ANOVA, P > 0.05), the seasonal effect showed significant differences with the highest average catch rates in summer–autumn (ANOVA, P < 0.05). A significant relationship between catch rate and sea surface temperature was found (P < 0.05), with a correlated coefficient value of r = 0.78