Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

A study was carried out on two important recreational fishing rivers in southern Chile, the Petrohué and the Puelo, to assess the population structure of the salmonid species inhabiting both rivers. Five river sectors were surveyed on four dates between April 2016 and February 2017. In the Petrohué River, 2400 fish were sampled (42.9% rainbow trout Oncorhynchus mykiss; 23.8% brown trout Salmo trutta, and 33.3% Chinook salmon Oncorhynchus tshawytscha), while in the Puelo River, 1972 fish were examined (51.6% rainbow trout; 30.4% brown trout and 18% Chinook salmon). Fry and fingerling stages accounted for the highest proportion of fish collected by electrofishing. In the Petrohué and Puelo rivers, rainbow trout fry and fingerlings represented 96.3 and 99.2% of the fish sampled, respectively; 96.8 and 97.1% in the case of brown trout, while for Chinook salmon, parr and pre-smolts represented 97% of the fish examined in the Petrohué River and 98.3% in the Puelo River. Rainbow and brown trout shared the same habitats and food items in both rivers, and the two oldest trout recorded 5+ and 6+years. Parr and pre-smolt Chinook salmon were present mainly in the winter and spring seasons and were aged 1+ and 2+, respectively. There were no differences in the food items recorded from the juvenile fish sampled in both rivers. The mature, returning adult Chinook salmon aged between 1.5+ and 1.6+ years were devoid of food and were recorded over the autumn season with the highest abundance in the Petrohué River. The study did not identify any adverse competition or negative interactions among the three main salmonid species sharing the same habitat. 

The relationship between climate variability and the small-scale fishery (SSF) of the Albuquerque Cays was studied from 2004 to 2018. The environmental variables analyzed were: sea surface temperature (SST), wind magnitude, and chlorophyll (Chl-α). The fishery is multi-species; 410 individuals were identified, belonging to 4 orders, 15 families, and 62 species, of which 38.7% are reef, 35.5% demersal, and 25.8% pelagic. The most dominant species were Caranx latus, Elagatis bipinnulata, Coryphaena hippurus, Lutjanus vivanus, Ocyurus chrysurus, Thunnus atlanticus, Sphyraena barracuda, Canthidermis sufflamen, Etelis oculatus, Acanthocybium solandri, Lutjanus jocu, Balistes vetula, Lutjanus buccanella, followed by Rhomboplites aurorubens and Mycteroperca bonaci. The pelagic species that contribute the most in biomass and commercial importance are S. barracuda, A. solandri, T. atlanticus, and E. bipinnulata, the most important due to their high market value. A significant correlation was found among SST, Chl-α, wind magnitude, and catch per unit effort (CPUE) anomalies. The highest CPUE values occurred in January, March, June and September were associated with the passage of cold fronts and hurricanes, giving way to new fishing opportunities and conservation of some resources.

The present work analyzes the current situation of scientific research on heavy metals and current regulations in macroinvertebrates (Penaeus) from the coastal region of the Gulf of Mexico. Its association with public health was identified based on national and international permissible limits for this fishery resource. The research analysis identified a high percentage of studies that report concentrations within the permissible limits established by the Mexican Official Standards and European regulations, reflecting a high percentage of consumption of this fishery resource that does not represent a risk to public health. However, specific cases exceeded national and international concentration limits, which justifies the importance of monitoring this fishery resource with emphasis on compliance with current regulations, supporting the need to redefine regulatory policies to address the current situation. Likewise, it is important to quantify these metals in a homogeneous, systematic, and continuous way to contrast the different studies on macroinvertebrates as environmental health bioindicator organisms and to know the distribution of these pollutants in the ecosystems inhabited by this important fishery resource.

We present information about new records of 11 species of chondrichthyans in the southern Gulf of Mexico, adding information about new specimens and occurrence of the species in Mexican waters. The second record of the Bathytoshia centroura, Mustelus sinusmexicanus, Mobula hypostoma and Squalus clarkae species for Mexico is presented, as well as new records in marine areas and the Lagoon Alvarado system corresponding to Hexanchus vitulus, Heptranchrias perlo, Scyliorhinus retifer and Squalus cubensis. In this paper increase the number of records for species of elasmobranchs to the southwestern region of the Gulf of Mexico, increase the distribution range and knowledge about the chondrichthyofauna of Mexico.

An abnormal embryo (male of 465 mm total length) and 13 other embryos were removed from a pregnant female bull shark (Carcharhinus leucas) caught in coastal waters between the Grijalva River and Terminos Lagoon in the southwestern Gulf of Mexico. The first record of synophthalmia and leucism in the bull shark is presented. The shark cyclopia case is reviewed.

The freshwater cladoceran Moina micrura has tremendous potential for mass culture as a live feed for larviculture. This study aimed to evaluate the efficacy of probiotics Lysinibacillus fusiformis A1 and Bacillus pocheonensis S2 in enhancing the population density, growth rate, and production of M. micrura under different environmental conditions. Four different temperatures (15, 20, 25, and 30°C), pH levels (4, 6, 8, and 10), and photoperiods (4L:20D, 6L:18D, 8L:16D, and 12L:12D) were set up. The daily number of individuals incubated under each environmental parameter was monitored for 12 days to determine the population density and growth rate of M. micrura. Meanwhile, the daily number of neonates from five females kept under respective environmental parameters was monitored until they died naturally. Probiotics were added individually at 5×104 CFU mL-1 twice during the first and sixth days of the experiment. M. micrura enriched with B. pocheonensis S2 at 30°C had the highest maximum population density (10 ± 0.2 ind mL-1) and the number of neonates produced (132 ± 6.43 ind), whereas treatment at 20°C had the best growth rate (0.1863 ± 0.006 d-1). M. micrura incubated with B. pocheonensis S2 at a normal photoperiod of 12L:12D had the highest maximum population density (10 ± 0.3 ind mL-1) and the number of neonates produced (129 ± 4.58 ind) while incubation at 8L:16D had the best growth rate (0.2879 ± 0.0007 d-1). M. micrura enriched with L. fusiformis A1 at pH 8 had the highest maximum population density (11 ± 0.8 ind mL-1), growth rate (0.5508 ± 0.04 d-1), and the number of neonates produced (129 ± 4.36 ind). Results recommend that a warmer temperature of 30°C, alkaline pH from 8 to 10, and a normal photoperiod of 12L:12D can be adopted for M. micrura enrichment with B. pocheonensis S2 to maximize its productivity for aquaculture use.

The effect of live yeast Rhodoturula glutinis was evaluated on juvenile Oreochromis niloticus cultivated in a Biofloc system. Growth performance and the expression of innate response and relevant oxidative stress genes were evaluated after a 12-week feeding trial. Three experimental treatments were evaluated in a conventional tilapia culture (control), Biofloc culture (BFT), and Biofloc with the addition of the live yeast R. glutinis 1×106 CFU g-1 (BFT+Rg), with four replicates per treatment. In all cases, commercial food was supplied to the organisms (32% protein and 5% lipids). O. niloticus juveniles (7.02 ± 0.04 g) were randomly distributed in 12 tanks, each with 15 animals. BFT+Rg treatment showed a significant increase in weight gain compared with the other treatments. Significant improvements were found in Fulton's condition factor, feed conversion rate, and hepatosomatic index under Biofloc conditions, BFT, and BFT+Rg treatments. No significant differences were observed in survival. R. glutinis directly influenced gene expression in the liver and intestine. The expression of tnfa, tgfb, hsp70, and gpx, genes in the liver significantly increased in the BFT+Rg treatment compared with the other treatments. Similarly, a significant increase was found in intestinal il1b, tnfa, tgfb, trf, hsp70 gpx, and cat expression patterns in the BFT+Rg treatment. Based on the performance and immune response, the present study suggests the use of R. glutinis as a strategy to increase the productivity of tilapia in Biofloc culture.

Striped bass, Morone saxatilis, is a marine species that belongs to the Moronidae family, which has great recreational and commercial importance and high production potential for human consumption. This research examines two acute stress factors that can be frequent in fish production units: a) handling is carried out constantly due to maintenance needs, size separation, growth evaluation, and health state, and b) hypoxia likely occur as the culture tank biomass, temperature, and fish metabolic rate increase. Juvenile fish (initial body weight 200 ± 3.0 g) were distributed in 110 L tanks and fed one week with different dietary tryptophan (Trp) levels: CD0.5 (0.5%), D1.0 (1.0%), D1.5 (1.5%) and D2.0 (2.0%). The fish were then exposed to stress by handling (5 min) or hypoxia (45 min). After that, blood hematocrit (Hct), hemoglobin (HB) and plasma cortisol, glucose (GLU), lactate (LACT), total protein (TP), albumin (AL), and globulin (GLOB) were analyzed, and AL/GLOB ratio was calculated. All analyzed parameters showed great sensitivity to acute stressors. Hypoxia increased Hct, cortisol, and GLU and decreased HB and LACT. Handling decreased HB and TP and increased GLU and LACT. D1.0 and D1.5 prevented Hct and LACT disturbance. D1.5 Trp prevented HB disturbance. All Trp supplemented diets prevented GLU change under hypoxia and TP change after handling. The results suggest that Trp played a role in M. saxatilis homeostasis restoration under acute stress.

In Ecuador, Peprilus medius is an important fishery resource whose destination is for local consumption and export. There are few local studies on its reproductive biology, and its capture is not regulated. Therefore, this study evaluates the most relevant aspects of its reproductive activity. Samples were obtained monthly from January to December 2017 from the capture of the purse seine fleet and the artisanal gillnet fleet landing near Manta. The morphometric analysis included the length-weight relationship, estimated using the allometry equation. The size at sexual maturity is based on the L50 criterion; the reproductive cycle was determined according to the monthly analyses of the gonadosomatic index (GSI), hepatosomatic index (HSI), and relative condition factor (Kn). A total of 334 specimens were analyzed, with average sizes of 22.0, 21.87, and 21.91 cm of total length (TL), for males, females, and combined sexes, respectively. Sex ratio was 1.17M: 1F (P > 0.05), while the length-weight relationship showed negative allometric growth for both males and females (b = 2.58; CI95% 2.48-2.72). Size at sexual maturity L50 was estimated at 21.84 and 21.23 cm TL for males and females, respectively. The GSI and HSI values and Kn showed significant differences among months (P < 0.05), with a marked seasonality during the single reproductive period. Mean size at first capture of 21 cm TL is recommended.

Rare earth elements (REE) and some transition metals (e.g. Nb) are a group of chemicals that have recently been widely used in industrial processes due to the increasing demand for new technologies. As a result, these chemicals are increasingly being released into the environment, which could mean that these pollutants could modify marine and terrestrial ecosystems. Seabirds, such as penguins, can biotransport pollutants and nutrients from the sea to land through excreta. However, there is no information about the role of the Humboldt penguin (Spheniscus humboldti) in bio-transporting emerging contaminants such as REE. This study aimed to assess any possible contribution of Humboldt penguins to the geochemical composition of some terrestrial areas. Excreta samples were collected from Chañaral Island, one of the most important sites in Chile for the conservation of Humboldt penguins. The results showed that this species tends to contribute to soil enrichment with REE (Ce, La, Nd, and Pr) and Nb through excreta, as well as with carbon. More studies are needed to see the potential impacts on the soil.