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The shortbill spearfish (Tetrapturus angustirostris) is a rare, large pelagic fish that inhabits the tropical and temperate waters of the Pacific and Indian Oceans, and it is seldom incidentally captured by the purse seine and longline tuna fleets. It is listed on the International Union for the Conservation of Nature red list as data deficient, with the population likely decreasing. The main objective of this paper is to contribute basic knowledge of the species catch rate, spatial distribution, temporal trends, and association with different types of fishing sets. A 23-year (1993-2015) database of incidental catches was analyzed; data was gathered by the observers from the Inter-American Tropical Tuna Commission aboard vessels from the international tuna purse seine fleet in the eastern tropical Pacific Ocean. We also analyzed time series of sea surface temperature (SST) from different Niño regions, and 2 climatic indices, the Oceanic Niño Index (ONI) and the Pacific Decadal Oscillation (PDO). The database included information from a total of 422,970 sets; of these, ~1% resulted in a catch of 687 spearfish. Most incidental catches occurred in waters close to the equator (10°S to 10°N), with no apparent seasonal distribution pattern. Time-series analyses showed a significant positive trend in incidental catch (~4% per year). Weak negative correlations of incidental catches with El Niño SST and ONI suggest that spearfish prefer cool waters in zones near the Equator. The PDO seemed to be more important to spearfish than El Niño events, and it is likely playing an important role in the positive trend of incidental catches. Most spearfish catches were associated with sets made on floating objects, mainly south of the equator and west of 100°W, highlighting the oceanic behavior of this species. [ABSTRACT FROM AUTHOR]

The main objective for this study was to provide information on the relationship between dolphinfish (Coryphaena spp.) catches and the environmental conditions, which could help to explain dolphinfish movements in the eastern tropical Pacific Ocean off the coast of Mexico--a topic that is still under debate. We analyzed a 10-year (2004-2013) database of estimated incidental catch from the Inter- American Tropical Tuna Commission, reported by observers on board tuna purse-seine ships. Significant seasonal and interannual differences were found in the incidental catch. No segregation due to size was apparent. Two areas of high catch were present in the study zone: one near the Baja California Peninsula that is especially productive during summer, and a second in an oceanic area (~15°N, 120°W), which is present all year long but becomes more important during May-June. Using satellite images, we found that the 2 species of dolphinfish preferred warm waters (24-28°C) with low concentrations of chlorophyll-a (<0.02 mg/m3), and mainly positive values of sea-surface height, all of which suggested that dolphinfish spp. associate with oceanographic features, such as anticyclonic eddies. There was a seasonal SE-NW-NE movement of high incidental catch across survey quadrants (1°×1°), movement that is closely related to the latitudinal displacement of the 25°C isotherm. [ABSTRACT FROM AUTHOR]

Fishery catch data on yellowfin tuna (Thunnus albacares) were examined to study the effects of El Niño events between 1990 and 1999 for an area in the northeastern tropical Pacific (18-24°N, 112-104°W). The data were extracted from a database of logbook records from the Mexican tuna purse-seine fleet. Latitudinal distribution of the catches increased from south to north for the 10-year period. Highest catches and effort were concentrated between 22°N and 23°N. This area accumulated 48% of the total catch over the 10 year period. It was strongly correlated with El Niño-Southern Oscillation (ENSO) events. At least two periods of exceptionally high catches occurred following El Niño events in 1991 and 1997. Peaks of catches were triggered by the arrival of positive anomalies of sea surface temperature (SST) to the area. A delay of two to four months was observed between the occurrence of maximum SST anomalies at the equator and peaks of catch. Prior to these two events, negative SST anomalies were the dominant feature in the study area and catch was extremely low. This trend of negative SST anomalies with low catches followed by positive SST anomalies and high catches may be attributed to northward yellowfin tuna migration patterns driven by El Niño forcing, a result that contrasts with the known behavior of decreasing relative abundance of these tuna after El Niño events in the eastern Pacific. However, this decrease in relative abundance may be the result of a local or subregional effect. [ABSTRACT FROM AUTHOR]

Analyzes the structure of fish communities that inhabit the Espiritu Santo Island and the Espiritu Santo Seamount in the lower gulf of California, Mexico. Hydrographic parameters; Most common species near the island; Change in fish abundance and diversity seasonally between the island and the seamount; Topographical differences between the two sites.

The white mullet Mugil curema is distributed along the Gulf of Mexico and Pacific coasts and constitutes an important food resource in Mexico. However, during recent years the capture of this mugilid has decreased considerably, especially in Bahía and Ensenada de La Paz, Baja California Sur, Mexico. The effects of different levels of temperature (22, 26, and 30°C) and salinity (15, 25, and 35) on the instantaneous growth rate, energy content, and condition factor of early juveniles of Mugil curema were evaluated. Fish showed a lower growth rate, lower body energy content, and a less condition factor when exposed to high salinity and temperature. On the basis to the results obtained and considering the unusual extreme temperatures and salinity registered in Ensenada de La Paz, it is expected low functional performance of juvenile mullets beyond the overfishing might contribute to the population decrease of this resource. [ABSTRACT FROM AUTHOR]

Dolphinfish are little known migratory fish targeted by sport, artisanal and commercial fleets. In this study, we analyzed a 10 year database of incidental catches of the tuna purse seine fleet in the Pacific Ocean off Mexico with the aim to understand the environmental determinants of the spatial distribution and seasonal migration patterns of dolphinfish. We modeled the probability of occurrence of dolphinfish as a function of spatial (geographical coordinates), temporal (month/year) and environmental variables (sea surface temperature [ SST], chlorophyll [ CHL] and sea surface height [ SSH], inferred from satellites) using logistic Generalized Additive Models. Dolphinfish preferred waters with SST values from 23 to 28°C, low (<0.2 mg/m3) CHL values, and primarily positive SSH values. Two dolphinfish hot spots were found in the study area: one in an oceanic zone (10°-15°N, 120°-125°W), which was more defined during spring, and one on the Pacific side of the Baja California Peninsula, which became important during summer. Models suggested that dolphinfish migrated through the study area following a 'corridor' that ran from the Gulf of Tehuantepec along the Equatorial Upwelling zone to the oceanic hot spot zone, which in turn connected with the hot spot off the BCP. This 'migratory corridor' went around the Eastern Pacific Warm Pool, which suggested that dolphinfish avoided this high temperature-low production zone. Dolphinfish occupied zones close to certain oceanic features, such as eddies and thermal fronts. Results suggested that the primary cause of the biological hot spots was wind-driven upwelling, because the hot spots became more important 3-4 months after the peak in upwelling activity. [ABSTRACT FROM AUTHOR]

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 (19°-24° N, 104°-112° 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 (>28°C) 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 18°C 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. [ABSTRACT FROM AUTHOR]

Estimates of net ecosystem exchange (NEE) of CO2 have been measured on a variety of ecosystems world wide including grasslands, savannahs, boreal, pine, deciduous, Mediterranean and tropical rain forests as well as arctic tundra. While there have been numerous comparisons between net primary productivity of arid and semiarid grasslands and shrublands, notably lacking are estimates of NEE with a few exceptions. The objective of this study was to characterize the seasonal and annual carbon flux of a desert shrub ecosystem using the eddy covariance technique to determine the sensitivity of the system to the timing and varying amounts of precipitation. Measurements began in July of 2001, a year with 339 mm of rainfall, considerably above the long-term average of 174 mm and preceded by 2 years of below average rainfall (50–62 mm). Over the 2 complete years of measurements, precipitation was 147 and 197 mm in 2002 and 2003, respectively. In all years, the majority of the precipitation fell between August and September. The site was a sink of−39 g C m−2 yr−1 in 2002 with a relatively strong uptake in the early part of the year and reduced uptake after the suboptimal rainfall in September. This contrasts with 2003 when the ecosystem took up−52 g C m−2 yr−1 concentrated in the fall after significant rain in August and September. Likely, extremely low rainfall years would result in a carbon loss while a strengthening of the typical winter secondary peak in precipitation (notably absent in the 2 years of measurements) may extend uptake into the spring resulting in more carbon accumulation. The system appears to be buffered against variations in annual rainfall attributed to water storage in the stems and roots. [ABSTRACT FROM AUTHOR]

Presents a study that examined the occurrence of yellowfin tuna at Espiritu Santo Seamount in the Gulf of California. Methods; Results; Discussion.

The common dolphinfish (Coryphaena hippurus) is an important resource for the sport-fishing industry in Mexico. It is captured incidentally by the eastern Pacific purse-seine tuna fishery and in coastal areas by artisanal fisheries. Although it is considered a highly migratory species, only few studies of its movements are available. In this study, the behavior of the common dolphinfish was analyzed by means of acoustic telemetry at three locations within La Paz Bay (southern Gulf of California) from summer to autumn 2013. Acoustic transmitters were attached to six individuals and they were tracked for periods of up to 48 h. Every hour, vertical profiles of temperature and bathymetry were made. To determine the effect of biotic (sex) and abiotic (water temperature and depth, thermocline depth, hour, and bathymetry) variables on the horizontal and vertical movements of tagged organisms, generalized additive mixed models were applied. The results showed a tendency of horizontal movements to the southwestern zone of the bay; two individuals crossed from the eastern to the western side. The average speed was 0.51 m s-1. The vertical movements showed that the individuals spent 80% of the time above 34 m depth, of which around 45% was spent in the upper 10 m of the water column. During daylight hours they swam in shallow waters (upper 10 m) and at night they performed deeper dives (73 m maximum depth). Biotic and abiotic variables influenced both types of movements; however, bathymetry and temperature largely explained fish movements. [ABSTRACT FROM AUTHOR]

Diet composition of the sailfish Istiophorus platypterus from the southern Gulf of California was determined using stomach contents of 576 fish. They were sampled from 1989 to 1991 from the sport fishing fleet at six tourist ports of the Mexican Pacific (La Paz, Cabo San Lucas, Mazatlan, Puerto Vallarta, Barra de Navidad, and Manzanillo). A total of 78 different prey taxa was classified and 64 were identified to species. From the diet composition and using the percent of index of relative importance (IRI), three feeding zones were determined by using cluster analysis. The most important prey by zones were in Zone I, La Paz: Dosidicus gigas, Scomber japonicus, and Auxis spp.; Zone II, Cabo San Lucas: Auxis spp., Selar crumenophthalmus, and Lagocephalus lagocephalus; and Zone III, Mazatlan, Puerto Vallarta, Barra de Navidad, and Manzanillo: Argonauta spp., D. gigas, and Auxis spp. We suggest that sailfish in Mexican Pacific waters are generalist predators feeding mainly on epipelagic species in coastal and oceanic waters, and occasionally diving to prey on demersal fish. The changes in diet composition among zones seem to be related more to abundance and distribution of the prey than to food preferences. [Copyright &y& Elsevier]

Deals with a study which presented an analysis of the stomach contents of 500 dolphinfish Coryphaena hippurus in Cabo San Lucas, Baja California Sur, Mexico. Categories of food items discovered; Materials and methods; Results.