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This study aimed to evaluate morphological differences between cultured and wild common carp, Cyprinus carpio L. Wild specimens were collected from fishers operating in the waters of the Shatt al-Arab River, Basrah, Iraq, while cultured specimens were obtained from the Aquaculture Unit of the Marine Science Centre, University of Basrah, Basrah, Iraq. Significant changes were detected in all eight morphometric and three meristic characters measured and counted. Boxplots by habitat and variable showed high divergence between the populations. The meristic counts were also higher in the cultured population, and, ultimately, the two populations diverged.

This study was supported by Agencia Nacional de Promoción Científica y Tecnológica (Project PICT 2015-1823), Universidad de Buenos Aires (grant number UBACyT 20020150100052BA),Programa Becar (Ministerio de Educación, Argentina), Universidad Autónoma Metropolitana-Iztapalapa and Secretaría de Educación Pública-Consejo Nacional de Ciencia y Tecnología (grant no. Ciencia Básica/2011-01-165569), Government of Principality of Asturias pain (project IDI/2018/000186 – Fondos Feder), Scientific-Technical Services (SCTs) of Oviedo University, Brazilian National Council forScientific and Technological Development – CNPq (N.N.F., grantno. 311785/2018-2), and the State Funding Agency of AlagoasFAPEAL (grant no. 60030 0020401/2017).

The white mullet Mugil curema supports several fisheries in the neotropical region; nevertheless, the population structure is still elusive. The aim of this study was to assess the presence of adult management units and nursery areas from five sampling sites throughout the Gulf of Mexico and northern Brazil using otolith microchemistry. The Li/Ca, Na/Ca, Mn/Ca, Sr/Ca, Ba/Ca and Pb/Ca ratios were measured in otolith core (juvenile stage) and edge (adult stage) (N = 131) using laser ablation-inductively coupled plasma-mass spectrometry. Several ratios were significantly different between sampling sites for core and edge (P 0.05). For otolith edge, permutational multivariate analysis of variance showed significant differences (P 0.05) between all sampling sites from Mexico (except between Mecoacán and Tamiahua, P 0.05) and between Mexico (pooled samples) and Brazil. Quadratic discriminant analyses showed jackknifed classification higher in the edge (66.6% and 99.5% for Mexico and Brazil plus Mexico, respectively) than in the core (46.3% and 76.5% Mexico and Brazil plus Mexico, respectively). The two cluster analyses based on the core microchemistry (Mexico and Brazil plus Mexico) produced three main clusters, which did not coincide with catchment areas. These results support the segregation of the M. curema adult life stages among several sampling sites from Mexico and Brazil; moreover, core analysis suggested that the nursery areas did not correspond to the capture sites or adults stocks.

This study was designed to assess morphological changes between cultured and wild tilapia, Oreochromis niloticus (L.). Wild fish samples were obtained from fishermen operating in the waters of the vicinity of the province Parakou, Benin in November 2014, while the cultured samples were obtained from a fish farm in the municipality of Sô-Ava in the Atlantic region of the southern part of the Republic of Benin. Significant differences were observed in all nine morphometric traits measured. Discriminant analysis of morphometric parameters showed high divergence between the populations. The meristic count, however, overlapped broadly showing no divergence between the populations. The morphometric differences between the cultured and wild tilapia, O. niloticus, could have been linked to genetic differences or environmental factors or a combination of these.

Tilapia juveniles live in littoral regions of freshwater ecosystems which have temperatures that may reach critical values for growth, especially in face of the onslaught of climate change. This study analyzes the effect of temperature (25, 30, 35, 40°C) on the growth and survival of hybrid tilapia juveniles in a re-circulating system. Duplicate groups of 30 juveniles were stocked in 200 L tanks in a closed, re-circulating system. Automatic heaters were used to establish the water temperatures, commercial food was supplied at 5% of their weight as daily ration. Fish were weighed and measured at 15-day intervals for a period of 3 months. Water temperature and dissolved oxygen were monitored daily. Ammonia, nitrates and dissolved reactive phosphorus were monitored every third day. Fish responses were estimated through variations in length, weight and inter-circuli space of fish scales. Average initial and final weight and length, Specific growth rate (SGR), Fulton Index (FI), Length-weight relationship and survival were used to assess tilapia growth performance. Weight, length, SGR and FI were significantly affected (P < 0.05) by water temperature. Growth of the fish reared at 30oC was almost one third greater than that at 25°C and one sixth greater than that at 35°C. Except for fish reared at 40°C, the other treatments showed a positive allometric growth, with the better results recorded for the 30 and 35°C treatments. The fish reared at 40°C survived only two weeks while the survival rate of 98, 90 and 88.3% for 25, 30 and 35°C, respectively.

Cytochrome c oxidase I (COI) and microsatellite markers were used to evaluate the genetic structure, connectivity, and evolutionary history of white mullet (Mugil curema), along locations in the Atlantic, Gulf of Mexico (GoM), and Pacific coasts. DNA sequences of 125 COI were obtained and identified as Mugil curema with 100% identification and coverage. COI sequences resulted in the formation of two haplogroups, one in the GoM along with a location in Oaxaca named Huave System (HU), belonging to the Pacific coast, and another one in Mexican Pacific (MP, with exception of the former). The evolutionary history of both haplogroups concur with the closure of the Isthmus of Panama (1.5 My). The MP haplogroup showed a subdivision in a northern group and a southern group, with a separation of 0.4 My that could be the result of a combination of Pleistocene factors and oceanographic changes following the closure of the Isthmus of Panama. Furthermore, microsatellites result also revealed that the GoM/HU haplogroup has larger genetic distances with other samples from the MP than with those of the GoM; this result was confirmed with the individual allocation analysis. The presence of Huave System mullets within the GoM lineage may be due to the confinement of individuals in this locality, that have retained ancestral polymorphisms of the GoM sister lineage, or to a recent connection. The genetic similarity of fish populations in both coasts of Mexico is a completely new report on a species that recently connected the Pacific and Atlantic coasts.

The shape of fish scales is, to a considerable degree, species-specific, making it possible to identify species using only one fish scale per specimen. However, to our knowledge, the shape of the rhombic lamination pattern has not been considered to identify species. This study used landmarks and geometric morphometric approaches to address two questions: (1) whether the rhombic lamination pattern of fish scales along the longitudinal axis varies within species and sex and (2) how many fish scales of the rhombic squamation pattern should be considered to obtain an adequate identification. These questions were assessed with a MANCOVA and a cross-validated quadratic discriminant analysis (DA) using the rhombus of one, three, and six scales, and 6, 14, and 26 landmarks, respectively, in order to discriminate between two co-generic species, Mugil cephalus and Mugil curema. Proportions of the total shape variance explained by the total length and the centroid size were 2.3, 11.8, and 10.5% and 4.2, 5.1, and 5.4% for one, three, and six scales, respectively. Thus, analyses were performed on the shape and the form (shape plus size). The MANCOVA and DA analyses were found to be effective in detecting differences in scale pattern shape between species (except in the case of three scales; p = 0.079 for the shape and p = 0.065 for the form), whereas no differences were recorded between size and sex in all cases. Findings indicate that a good identification of species is possible, with no significant differences when using shape or form. The DA provided values of 75.8, 75.0, and 73.4% based on the shape, and of 72.7, 75.8, and 75.0% based on the form, for 1, 3 and 6 scales, respectively. Thus, it is possible to obtain a rapid and reliable identification of species using the rhombus of one scale only without considering the size. This is a useful finding in practical terms since scaling requires data on length. The finding of a suitable discrimination using only the rhombus of one scale raises the possibility of using an ocular adaptor on a camera or mobile phone, allowing many individuals to be easily screened without having to collect scales.

Mugil curema is a teleost fish of economic importance that shows wide phenotypic variability in the coasts of Mexico. Intraspecific morphological variability might replicate either genetic dissimilarity between groups or environmental conditions according to phenotypic plasticity. Fish scales shape was used to discriminate location variants, genetic structure obtained by microsatellite markers, and marine ecoregions of Mexico. The present study uses landmarks and geometric morphometric statistical approaches to address the specific question: if and how fish scale shape varies with genetic structure or with marine ecoregions. This is assessed using seven landmarks by scale, the coordinates of which were subjected to a generalized Procrustes analysis, followed by a principal components analysis and quadratic discriminant analysis with cross-validation analysis on shape. Also, the significance of classifications was assessed by multivariate analysis of covariance (MANCOVA). The proportion of total shape variance explained by total length and by centroid size was 3.8 and 3.0%, respectively. Therefore, only shape (without size) was used for the analysis. MANCOVA was significant in all cases, with locations, genetic structure, and marine ecoregions. The cross-validated discriminant analysis by location correctly classified 42.2%, whereas with the genetic structure prearrangement and marine ecoregions, the identification rates were 58.3 and 57.0%, respectively. It was surprising that, as the same as in the genetic structure (microsatellite analysis), San Antonio Bay, Texas formed a group with Sabancuy, Campeche, Celestun, and Sisal, Yucatan (the Caribbean locations). Likewise, Huave Lagoon System, Oaxaca, located in the Pacific coast is more similar to the Caribbean sites unlike the other locations from the Pacific area, which are similar results depicted with microsatellite analysis. On the other hand, using the marine ecoregions arrangement, the findings indicate that the Mexican Tropical Pacific and the Chiapas-Nicaragua marine ecoregions were very different as opposed to the two marine ecoregions from the Gulf of Mexico more similar in fish scale shape. The Mexican Tropical Pacific ecoregions show more identification rate (80.4%), whereas the rest of marine ecoregions discriminate less than 53.3%. Possibly, hydrographic features as currents or upwellings circumscribe boundaries between marine ecoregions, and this could produce inherent genetic structure.

New Zealand rattail fish are of great interest both to biologists who study their phylogenetics and in fisheries. In contrast, their morphological evolution is little studied and poorly understood. Geometric morphometric methods based on scale shape were applied in this study to determine differences among species and genera. Scale shapes were described using seven landmarks, the coordinates of which were subjected to a generalized Procrustes analysis, followed by a principal components analysis. A cross-validated discriminant analysis was applied to assess and compare the size-shape (centroid size plus shape variables) efficacy in the species and the discrimination of the genera. Two main phenetic groups were identified: cluster no. 1 with eight species and cluster no. 2 with six species. Coelorhinchus aspercephalus and Mesovagus antipodum were more separated from the other species in the first cluster. The cross-validated canonical discriminant analysis correctly classified 74% at the genus level, with most misclassifications occurring between Coelorhinchus and Coryphaenoides, whereas the best classified genera were Mesovagus and Trachyrincus. The discrimination of correctly classified species ranged from 41.2 to 100%. The highest correct classification rates were recorded for Coryphaenoides armatus, Coelorhinchus innotabilis, Trachyrincus longirostris and Mesovagus antipodum.

This study documents the presence of crypsis in Mugil curema juveniles under laboratory culture. Initially, the juveniles were located in one brown tank (BT1), later almost half of the individuals were placed in a white tank (WT) where they showed a pigmentation change to white. After being moved to another brown tank (BT2), the juveniles changed to their brown original colour, but kept a few small white spots on the dorsal axis of the body. The ventral head melanophore pattern also changed in the white specimens. Temperature (°C), oxygen (mg l−1) and Illuminance light (Lux m−2), total length (mm) and total weight (g) were determined by tank. Chromaticity was measured in L*(relative luminance) a*(measurement relating to the redness or greenness of the light) b*(measurement relating to the yellowness or blueness of the light) coordinates where all three values are required to completely describe an object’s colour. One-way ANOVA showed no differences for temperature, oxygen and illuminance light among tanks. Length and weight were similar for BT1 and WT but both were different from BT2. The white juveniles depicted similar L* as the WT background as well as the dorsal area of the brown pigmentation and converted juveniles to the brown tanks BT1 and BT2, respectively. Therefore, the fish's body relative luminance matches the background. To our knowledge this behaviour has not been reported before for any fish mullet either cultured or living in the wild.

The white mullet (Mugil curema) is a species of wide geographical distribution on both coasts of America, inhabiting coastal lagoons, estuaries and rivers. Adults form schools and migrate into the open sea to spawn, where both eggs and hatchlings are subject to transport by surface currents. In northern Gulf of Mexico, under the influence of temperate waters M. curema has a single spawning in spring and summer, while in southern Gulf of Mexico, with warmer environments, spawnings are in summer and winter. These asynchronous spawning may point to the existence of different populations, while the planktonic mobility of eggs and larvae open the possibility that the putative populations mix together. Aiming to address whether there are different genetic groups of M. curema, ten coastal sampling sites along the Gulf of Mexico plus one site in the NE Atlantic coast were selected. A total of 363 individuals comprising all sampling sites were analyzed by means of microsatellites. 10 loci were tested and the number of alleles per locus varied between 7 and 19. All loci showed significant genetic differentiation (FST = 0.287), while Evanno test resulted in a K = 3 value, suggesting that three is the most probable number of M. curema groups in the studied area. This grouping is possibly associated with spawning time, contrasting oceanographic conditions in the north, center, and south of the Gulf of Mexico, as well as ecological and geomorphologic differences between lagoon environments; giving as consequence variations in the history of life of M. curema populations.

Mugil cephalus generally inhabits coastal areas and migrates to the open sea to reproduce. Based on tagging studies, it has been suggested that this species could present philopatric behavior, which would be reflected in the genetic structure. To test philopatry in M. cephalus, 11 locations in the Gulf of Mexico (GOM) and three in the Mexican Pacific (MP) were sampled. 151 and 177 specimens were analyzed using mtDNA, COI and control region, respectively. Ten microsatellite loci were examined in a total of 311 individuals. COI results showed that GOM and MP do not share haplotypes. Each littoral represents a distinct genetic group with a genetic distance of 5.4%. However, historical genetic flow was found between these two regions, which could represent a remnant of the connection at the Isthmus of Panama or due to the interconnection of rivers during the Pleistocene on the Isthmus of Tehuantepec. The GOM presented panmixia (FST = 0.001 COI, 0.023 control region, and 0.039 microsatellites), and the high gene flow between locations (Nm > 139) could lead to the underestimation of the markers of philopatric behavior. The MP also presented panmixia using COI (FST = 0); however, it showed two genetic groups (north and south) using microsatellites in both sexes (FST = 0.176 ♂ and 0.144 ♀). Given the evidence that the Tehuanos winds can produce a barrier between the locations of the MP, particularly during the spawning season, it is possible that genetic structure is the result of this barrier rather than philopatry.

In the present study a comparison of the otolith morphology of two species of parrotfish, family Scaridae, collected from the Red Sea coast of Egypt, is conducted to identify the most appropriate taxonomic characters that separate these species. Ontogenetic changes in the otoliths of the two scarid fishes become evident. In the otoliths ofChlorurus sordidus, the following characters are comparable in small-sized adult fishes: otolith width, otolith depth, mesial surface shape, lateral surface shape, shape of sulcus acusticus, column, rostrum and size of rostrum. The otoliths of young adults (GI)C. sordidusdiffer from the adult ones in 14 out of the 22 characteristics studied. In the otoliths ofHipposcarus harid, the following characters are comparable in small and large fish: otolith width, otolith depth, mesial and lateral surface shapes, shape of sulcus acusticus, rostrum and size of rostrum.

The effectiveness of discrimination of phenotypic stocks was compared between otolith and scale shapes for Mugil curema specimens collected at five different locations in the Gulf of Mexico and two locations along the Pacific coast during two consecutive years. Geometric morphometric methods were used to determine the discrimination among locations using seven and 22 landmarks for scales and otoliths, respectively. The cross-validated discriminant analysis by location correctly classified 43.2 and 40.2% based on shape variables (Principal Components scores) for otoliths for all locations jointly, while for scales the classification percentages were 48.7 and 47.4% for the first and second years, respectively. Classification results improved when the discrimination analyses were carried out for pairs of locations, with 51.4 to 82.6% for otoliths and 72.7 to 97.1% for scales. The analysis was run for two consecutive years and the results for both years were best for the scales. Thus, fish scale shape offers a straightforward, non-destructive, accessible, quick and inexpensive method to trace fish phenotypic stocks.

The proliferation of dams in Mexico between the 1940s and 1970s enabled the development of culture-based fisheries, especially those of exotic species, in order to increase the availability of cheap protein for the poorer social classes. This chapter describes the fishery policies and the stocking situation over the last 15 years for seven geo-economic regions, as well as from 1974 to 2013 on a national scale, based on official information provided by the Mexican government (Federal Fisheries Agency, National Commission on Aquaculture and Fisheries, CONAPESCA). The present fishery production in Mexico accounts for c. 1.7 million tonnes/year, of which 10.3% is derived from inland waters. Up to 2003, most of this production (±85%) corresponded to fisheries based on fish stocking. However, this trend changed over the last decade, and at present, the production of intensive systems is almost equal to extensive systems. Intensive systems increased production over the past 5 years, and in 2014, their production is close to extensive systems. This change is the result of the government policies of the last administrations in Mexico, and it took place without a formal cost/benefit analysis of fish stocking. Under this scenario, we mean to respond to the following questions: What species have been used in stocking freshwater areas in Mexico? Is fish stocking related to yield? What are the strategies the Mexican government has followed for fisheries based on fish stocking? What is the general tendency of fisheries based on fish stocking in Mexico?

Oreochromis niloticus has been introduced worldwide into freshwater reservoirs and represents an alternative food for local populations. Two annual marks on fish scales have been reported for fish in these environments, one of them is allocated to reproduction, while the other is thought to be formed following low temperatures, a reduction in oxygen concentration and/or high densities, among others. In order to explore the causes of this second ring, we designed an experimental study to analyze the influence of four factors: a reduction in food amount, an increase in density, a decrease in oxygen concentration and temperature. The experiment was carried out using five 215 L plastic tanks, each one divided into two sections, so as to have treatment replicates (each with 20 juveniles). The control conditions were optimal for the species: 5% of body weight in food, a density of 3 fish/L, a total oxygen saturation of 4.98 ± 0.5 mg/L, and a temperature of 25.0 ± 1.0oC; the treatments varied as follows: food of 2.5% of body weight, density of 6 fish/L, oxygen of 2.8 ± 1.2 mg/L and a temperature of 19.6 ± 1.0oC. Fish responses to stressors were estimated through variations in length, weight and inter-circuli spaces or circuli spacing in fish scales. Every third day it was measured the concentrations of ammonium, phosphates and nitrates with a photometer. Three stages for length/weight fish measurements and scales sampling were considered: 1) Initial stage: before experiment started, 2) Final stage: at the end of the experiment, and 3) Compensatory stage: when all the experimental treatments were adjusted to the Control conditions; the experiments lasted for three weeks. The results indicated that all the treatments caused a reduction in length, weight and inter-circuli spaces when compared to the controls (6.7 ± 0.5 cm; 5.2 ± 1.2 g; 5.4 ± 0.5 mm, respectively), but only the variables of temperature and food resulted significant (5.6 ± 0.4 and 5.8 ± 0.5 cm; 3.4 ± 0.7 and 3.3 ± 0.9 g; 3.4 ± 0.3 and 4.1 ± 0.6 mm for temperature and food treatments, respectively) (P < 0.05). When treatments were reversed to the control conditions for another three weeks compensatory growth was observed in the oxygen and density treatments, but not in the same way for the temperature and food treatments. We concluded that inter-circuli distances are a good indicator to stress periods in this species.

The present study examined variation in sex ratio (SR), fecundity, gonadosomatic index (GSI), condition index (K), and weight-length relationship in white mullet, Mugil curema (Valenciennes, 1836), and striped mullet, Mugil cephalus (Linnaeus, 1758) collected from eight locations in western Gulf of Mexico waters. Fish were sampled from commercial mullet fishers during two consecutive fishing seasons (November�March), beginning in 2008. Significant male- and female-dominance was detected for both species depending on location, with greater female dominance for white mullet and male dominance for striped mullet. In general, geographic differences in relative fecundity, GSI, and K in the present study were minor. However, several of these values were lower than values previously reported for the same study region from the early 1990s. We suggest that the differences may be related to increases in commercial fishing intensity.

By using freshwater fish stocking information from the Mexican government, this work described the current situation of the national stocking and its associated fishery policy. There is a lack of effective freshwater stocking programmes as a result of limited fisheries management, unharmonized fisheries regulations and institutional performance. The fry production has decreased from 140 to 20 million in the past 11 years.

Development of ecosystem-based fisheries management models depends, to a large extent, on the availability of trophic interaction data. These models could address ecological questions, examine ecosystem trophic structure, and be used in placement analysis for marine protected areas, among other uses. Many studies on fish trophic interactions have been conducted in the gulf of mexico over the past 120 yrs, and we are currently compiling data from these studies into a database. Here, we report on a collection of 747 references, investigate spatial and taxonomic distributions of the fish species examined, and identify data gaps. Metadata lite, a condensed version of customary metadata that answers the who, what, where, when, and why, has been collected on all studies, all references have been geocoded, and habitat characterizations have been standardized using the coastal and marine ecological classification standard for about 60% of the references. Visualization tools and products to assist in the synthesis, analysis, and interpretation of the data, including maps, network depictions, and dynamic interactions, are discussed. A survey of trophic data available for fisheries management models for managed species in us gulf waters appear to be adequate for at least 23 of 50 of managed species, while data for at least 14 species remain insufficient for model development assessment.

Menezes et al. (2010) show that Mugil cephalus Linnaeus, 1758 is different from Mugil liza Valenciennes 1836, the latter being the mullet found along the Atlantic coast of South America. They also suggest that individuals identified as M. cephalus from the northwest Atlantic could represent a population of M. liza in this region, since they doubt the presence of M. cephalus in waters colder than the ones of the West Indies. In order to clarify the presence of M. cephalus in the northwest Atlantic, this study compares meristic and morphometric measurements of M. cephalus and M. liza from the Gulf of Mexico with those obtained by Menezes et al. (2010) for M. liza from South America and for M. cephalus in the Mediterranean Sea. Results show that there are differences in both morphometric and meristic data between the two species. The morphometric measure that differentiates these species is the distance from the snout to the dorsal fin, which is positioned backwards in M. liza compared with M. cephalus. The body width is consistently greater in M. cephalus than M. liza. The meristic character that discriminates between both species is the number of scales in the longitudinal series that, in M. cephalus, ranges from 38 to 43 while in M. liza between 32 to 39. The information presented in this work confirms the presence of M. cephalus in the Gulf of Mexico and the sympatric presence of M. liza is established, even if its abundance is quite low.

Fish scale shape was used to identify geographic variants among Lutjanidae (Lutjanus argentiventris, L. guttatus and L. peru). Specimens were collected from three different geographic areas, north to south of the tropical Pacific coast of Mexico: Puerto Vallarta (PV), Manzanillo (MA) and Caleta de Campos (CC). Configuration of landmark coordinates of fish scales were scaled, translated and rotated using generalized procrustes analysis, followed by principal components analysis of resulting shape coordinates. Principal component scores were submitted to cross-validated discriminant analysis to determine the efficacy of scale landmarks for discrimination by geographic variants. This was done with shape and form (shape plus size). PV and MA were recognized as one population different from the CC sampling area. Using only shape (without size), identification rates predicted geographic variant membership much better than chance (91.3%, 70.6% and 85.4% for L. argentiventris, L. guttatus and L. peru, respectively), and taking size into account, classification is somewhat improved (90.6%, 80.1% and 87.5% for L. argentiventris, L. guttatus and L. peru, respectively). Consistency of the two populations for the three species shows non-fortuitous events. Population discrimination confirmed previous genetic studies that show a zoogeographic barrier between the North Equatorial Current and the California Current. The method is non-destructive, fast and less expensive than genetic analysis, thus allowing screening of many individuals for traceability of fish. La forma de las escamas se usó para identificar variantes geográficas de tres especies de Lutjanidos (Lutjanus argentiventris, L. guttatus and L. peru). Los especímenes se colectaron en tres diferentes áreas geográficas en la zona costera del Pacífico mexicano, de norte a sur: Puerto Vallarta (PV), Manzanillo (MA) and Caleta de Campos (CC). La configuración de coordenadas referenciadas de las escamas fueron escaladas, trasladadas y rotadas usando el análisis generalizado Procrustes, las coordenadas resultantes fueron sometidas a análisis de componentes principales mientras que los scores de los componentes se sometieron a validación cruzada con el análisis discriminante con el objeto de determinar la eficacia de las coordenadas referenciadas en la discriminación de las variantes geográficas. Esto se realizó considerando la forma y la talla. Los resultados mostraron que PV y MA se reconocieron como una sola población diferente de los ejemplares del área de CC. Usando solamente la forma de la escama (sin considerar la talla) las tasas de identificación entre las variantes geográficas fueron mejores que al azar (91.3, 70.6 y 85.4% para L. argentiventris, L. guttatus y L. peru, respectivamente) y agregando la talla la clasificación mejora un tanto (90.6, 80.1 y 87.5% para L. argentiventris, L. guttatus y L. peru, respectivamente). La consistencia en los resultados de dos poblaciones para las tres especies de lutjánidos muestra que este resultado no es fortuito. La discriminación de estas dos poblaciones confirma previos estudios genéticos que muestran una barrera geográfica entre la corriente Nor-ecuatorial y la corriente de California. El método no es destructivo es rápido y mucho más económico que un análisis genético además de permitir la revisión de una muestra amplia de individuos para la trazabilidad de peces.

The growth of aquaculture as an industry has accelerated over the past decades; this has resulted in environmental damages and low productivity of various crops. The need for increased disease resistance, growth of aquatic organisms, and feed efficiency has brought about the use of probiotics in aquaculture practices. The first application of probiotics occurred in 1986, to test their ability to increase growth of hydrobionts (organisms that live in water). Later, probiotics were used to improve water quality and control of bacterial infections. Nowadays, there is documented evidence that probiotics can improve the digestibility of nutrients, increase tolerance to stress, and encourage reproduction. Currently, there are commercial probiotic products prepared from various bacterial species such as Bacillus sp., Lactobacillus sp., Enterococcus sp., Carnobacterium sp., and the yeast Saccharomyces cerevisiae among others, and their use is regulated by careful management recommendations. The present paper shows the current knowledge of the use of probiotics in aquaculture, its antecedents, and safety measures to be carried out and discusses the prospects for study in this field.

Although the shape of fish scales is useful for determining stock membership, the role of extrinsic (e.g. habitat, food type) and intrinsic (e.g. growth) factors in determining variation in fish scales shape has not been determined. This study examined whether fish scale shape changes as a result of compensatory growth in juveniles of the cyprinid roach, Rutilus rutilus (L.) reared on a fish farm in the UK. This was analyzed using geometric morphometric methods. Sufficient evidence was generated to accept the assumption that food availability and type between different growing-out facilities resulted in compensatory growth and this was sufficient to cause scale shape differences. This was tested using multivariate analysis of variance (MANOVA) analysis with the principal components scores of specimens (PCs) as dependent variables, to investigate whether fish scale shape (where the configuration of landmark coordinates were scaled, translated and rotated) form (where the configuration of landmark coordinates were translated and rotated not scaled) and allometry free (allometrically adjusting scale shape according to length) are related to holding facility (as fixed factor). Cross validated discriminant analysis was used to assess and compare the efficacy of shape, form and allometry free information. Identification rates are much better than chance with allometry free and shape alone, and classification is improved when size is taken into account.

To understand their migratory environmental history and habitat use in Mexican waters, 31 striped mullet Mugil cephalus and 40 white mullet M. curema (family Mugilidae) were collected from three habitats (Tamiahua Lagoon, and Cazones and Tecolutla estuaries, Veracruz) in the western Gulf of Mexico. Sr:Ca ratios in otoliths of mullets were measured from the primordium to the otolith edge with an electron probe microanalyzer. Mullets were aged by counting the otolith annuli. The patterns in mullet otolith Sr:Ca ratio differed among habitats and between species, indicating that habitat use and migratory behavior differed between species. Variability in otolith Sr:Ca ratios was consistent with that of the environment inhabited by the mullets. They showed a more diverse euryhaline preference than the simple catadromous behavior expected. The Sr:Ca ratios in the core region of the otolith indicated that mullets can spawn in both offshore waters and nearshore brackish waters, or that spawning may occur in offshore waters and that onshore currents/winds carry the fertilized eggs into onshore waters where salinities are lower. Peak Sr:Ca ratios corresponded to otolith annulus deposition, which validated the difference in timing of seaward spawning migration between striped mullet (winter) and white mullet (spring).

The shape of fish scales is to a considerable extent species-specific and is also useful in the determination of stock membership. Size is also important in distinguishing fish scales, both in absolute terms and potentially through allometric effects on scale shape. The present study uses landmarks and geometric morphometric statistical approaches to address two specific questions: (1) if and how fish scale shape varies with a general measure of size; fish fork length. This is assessed by regressing shape on fork length and (2) To what extent size, expressed as fish fork length (FL), is an important factor that has to be taken into account in the identification of species. The analysis is conducted with five fish scales taken from particular body regions from the longitudinal and transverse axis. Cross-validated discriminant analyses are carried out on shape, form (shape plus size) and allometrically standardised data (i.e. allometrically adjusting scale shape according to FL). Using only shape (without size), identification rates are much better than chance, and by taking size into account, but not allometrically adjusting shape, classification is improved somewhat. Allometric adjustment fails to improve classification markedly beyond what is achieved using shape alone. Scales from the central region perform best for identification purposes. Subsequent analyses ignore anatomical sampling region and still achieve good classification by species, especially when size and shape are combined (form). The findings indicate that in large scale survey studies of fisheries or when only scales are readily available, good identification of species is possible irrespective of allometry and anatomical sampling region. As such, scales offer a cheap, rapid and reliable on-the-spot means of identification of fish that have been caught, even when no other material is available.

Variations in scales from nine regions on the flank of teleost fish were examined from the point of view of functional adaptation and with regard to which scales best differentiate species. Three teleost species were selected; two are from the genus Mugil, M. cephalus and M. curema, which are phylogenetically distant from the third, Dicentrarchus labrax. Scale form was described using seven landmarks, the coordinates of which were subjected to generalized Procrustes analysis followed by principal components analysis. Principal component scores were submitted to cross-validated discriminant analysis to assess the utility of each scale in identifying species. The best discrimination (98%) was obtained with the scale from the central-dorsal area. Scales from the anterior and central zones are relatively wide dorsoventrally and narrow anteroposteriorly. This appears to be related to the profile of the lateral body wall and with subcarangiform swimming. Scales from the posterior region are anteroposteriorly long and dorsoventrally narrow, this shape possibly being related to thrust. Despite the wide phylogenetic separation between mullets and D. labrax, the pattern of scale variation is similar. This may imply strong functional convergence, although studies of sister taxa with different swimming modes are required to confirm this. © 2009 The Linnean Society of London, Zoological Journal of the Linnean Society, 2009, 155, 834–844.

Check formation on scales of roach Rutilus rutilus was examined during their production cycle at a fish farm in England through analysis of circuli patterns. Regular check formation was associated with the movement of fish from one type of grow-out facility to another; this resulted in a sudden shift in growth rate and the formation of a new check. As these had the characteristics of annual marks, their formation potentially invalidates their use as structures to determine the age of individuals during recapture events that may follow their introduction to the wild. At low growth rates, the number of circuli was constant throughout the year; this situation changed when fast growth rates were achieved. Five methods of backcalculation were also validated. When the proportionality between the body length and scale radii was weak, backcalculation methods were poor in determining length at check formation.

Lake Metztitlán was dried up completely in the spring of 1998 and refilled in August of that year. In the period September-November, two cohorts of 1.6 million juveniles of a tilapia hybrid were stocked (Oreochromis aureus/O. niloticus), and monitored every month for one year. Since the date of birth of these juveniles was known, the analyses focused on whether the ring marks of the scales, sagittae and opercula or the circuli of the scales could be used to age them. The ring marks of the scales and opercula showed great variability, and the sagittae had a significant relationship with length, but it is unclear if at least the first ring mark could be formed at the hatchery and reflect changes in diet and/or tank movements in the fish farm. The circuli had a continuous regular behavior, with a formation rate of 10.38±0.93 and 11.38±0.95 circuli/month for the first and second cohorts, respectively. This proportion was maintained during the study period, and could be of help to calculate an approximate age of juveniles, especially in stocked fish that show multiple ring marks because of manipulation in fish farms and stocking events. Rev. Biol. Trop. 55 (3-4): 1005-1013. Epub 2007 December, 28.El lago de Metztitlán se secó completamente en la primavera de 1998, inundándose nuevamente en agosto del mismo año para ser repoblado entre septiembre y noviembre con 1.6 millones de jóvenes de un híbrido de tilapia (Oreochromis aureus/O. niloticus) en dos periodos. Ambas cohortes fueron monitoreadas mensualmente durante un año. Debido a que la fecha de nacimiento era conocida, el objetivo del estudio fue evaluar si las marcas anulares de las escamas, las sagittae y los opérculos, o los circuli de las escamas pueden usarse para estimar la edad. Los anillos de las escamas y opérculos mostraron gran variabilidad, mientras que las de las sagittae se relacionaron significativamente con la longitud, sin embargo no quedó claro si al menos el primer anillo podría haber sido formado por cambios en dieta o movimientos en los tanques de la granja de cultivo. Por el contrario los circuli mostraron una formación regular con una tasa de formación de 10.38±0.93 y 11.38±0.95 circuli/mes para la primera y segunda cohortes, respectivamente, proporción que fue mantenida durante el periodo de estudio y que puede ser usada para calcular la edad de los jóvenes, especialmente en organismos que muestran numerosos anillos debido a la manipulación sufrida en las granjas o debido a las "siembras".

Geometric morphometric methods (GMMs) were used to determine if scale morphology can discriminate be- tween genera, species, geographic variants, and stocks of mullet (Mugilidae). GMMs were used because they allow standard multivariate analyses while preserving information about scale shape, which is important in making biological interpretations of results. The method was tested on ctenoid scales from mullets collected from different areas of the Gulf of Mexico and Aegean Sea. Scales were submitted to generalised procrustes analysis, followed by principal com- ponents analysis of resulting shape coordinates. Principal component scores were submitted to cross-validated discriminant analysis to determine the efficacy of scale landmarks in discriminating by taxon and population. Fish scale form was least effective in discriminating populations from nearby areas, better when populations are more geographi- cally dispersed, and best between species and genera. Scale form variations reflected previous genetic studies that dif- ferentiated congeneric Mugil cephalus and Mugil curema, which are distinct from other Mugilidae. The method is nondestructive, quick, and less costly than genetic analysis, thus allowing many individuals to be screened. Resume : Nous utilisons des methodes morphometriques geometriques (« GMMs ») pour verifier si la morphologie de l'ecaille permet de distinguer les genres, les especes, les variantes geographiques et les stocks chez les mulets (Mugi- lidae). Nous avons choisi les GMMs parce qu'elles permettent les analyses multidimensionnelles habituelles, tout en conservant l'information sur la forme des ecailles qui est importante dans l'interpretation biologique des resultats. Nous testons la methode sur les ecailles ctenoides de mulets recoltes dans diverses regions du golfe du Mexique et de la mer Egee. Les ecailles ont ete soumises a l'analyse generalisee du logiciel procrustes, puis les coordonnees de forme obte- nues a l'analyse en composantes principales. Les positions des composantes principales ont ete soumises a une analyse discriminante a validation croisee afin de determiner l'efficacite des reperes sur l'ecaille pour distinguer les taxons et les populations. La forme de l'ecaille de poisson permet de discriminer moins bien entre les populations de regions ad- jacentes, mieux entre les populations plus eloignees geographiquement et le mieux entre les especes et les genres. Les variations de forme des ecailles refletent les resultats d'etudes genetiques anterieures qui distinguent les congeneres Mugil cephalus et Mugil curema qui sont differents des autres Mugilidae. La methode ne requiert pas la destruction de l'echantillon, elle est rapide et moins couteuse qu'une analyse genetique, ce qui permet de trier un nombre eleve d'individus.

The ‘smoothed’(4253e HT smoother) 6 year time series with a monthly periodicity of catches (where the increases of the catches reflect the spawning migration) of Mugil cephalus and Mugil curema, were correlated (Pearson correlation index) against the ‘smoothed’ data on rainfall, water temperature, daylight and tide monthly averages. Water temperature and M. curema spawning migrations had a negative correlation (r = −0·77), while tide monthly averages and M. cephalus spawning migrations were positively correlated (r = 0·84). The two environmental variables that showed highly significant correlations were water temperature and daylight (r = 0·85, P

A renewed interest in fish scale anomalies prompted the present study, wherein we document a wide range of scale morphological abnormalities, including deformities in shape and structure, of a large number of species. In the present study, 63 cases of deformities were reported from 23 fish species collected from five countries. The abnormalities observed are discussed within the framework of contaminated aquatic environments, with a goal of recognising the cause of abnormality. Deformed scales exhibited different shapes, showing both slight (n=52 cases) and severe (n=9 cases) abnormalities. The scale deformations described in the present study should help direct future work on the relationships between environmental condition and fish health.

Menezes et al. (2010) show that Mugil cephalus Linnaeus, 1758 is different from Mugil liza Valenciennes 1836, the latter being the mullet found along the Atlantic coast of South America. They also suggest that individuals identified as M. cephalus from the northwest Atlantic could represent a population of M. liza in this region, since they doubt the presence of M. cephalus in waters colder than the ones of the West Indies. In order to clarify the presence of M. cephalus in the northwest Atlantic, this study compares meristic and morphometric measurements of M. cephalus and M. liza from the Gulf of Mexico with those obtained by Menezes et al. (2010) for M. liza from South America and for M. cephalus in the Mediterranean Sea. Results show that there are differences in both morphometric and meristic data between the two species. The morphometric measure that differentiates these species is the distance from the snout to the dorsal fin, which is positioned backwards in M. liza compared with M. cephalus . The body width is consistently greater in M. cephalus than M. liza . The meristic character that discriminates between both species is the number of scales in the longitudinal series that, in M. cephalus , ranges from 38 to 43 while in M. liza between 32 to 39. The information presented in this work confirms the presence of M. cephalus in the Gulf of Mexico and the sympatric presence of M. liza is established, even if its abundance is quite low.

This study gives the first record of Mugil hospes distributed in the Gulf of Mexico. This species previously has been confused with its congener Mugil curema and can be easily differentiated by the shape of the ctenii on their scales.

"Durante los años 2001-2009, el gobierno federal produjo 780 millones de crías pertenecientes a 22 taxaque se sembraron en cuerpos de agua interiores. El principal propósito de esta siembra fue la repoblación con fines pesqueros. Mediante información del mismo gobierno, se analiza la relación producción-siembra de crías de los Centros Piscícolas federales y su efecto en la producción pesquera estatal en aguas interiores mexicanas. Se plantea que esta producción está relacionada con la siembra de crías que llevó a cabo la Comisión Nacional de Acuacultura y Pesca (CONAPESCA), organismo desconcentrado del gobierno federal. Lo anterior fue revisado al analizar la correspondencia entre la densidad de crías sembradas y los rendimientos pesqueros estatales. De los 22 taxa, 19 son especies de peces (7 nativas) y 2 son subespecies, 2 son anfibios nativos y 1 es un crustáceo malayo. En promedio, en el lapso, se sembraron anualmente 86.7 ± 37.9 millones de crías, de las que el 90% son tilapias y carpas, y sólo el 3% son especies nativas. La relación siembra/ha vs producción/ha muestra que a mayor densidad de siembra, se obtiene mayor rendimiento pesquero hasta alcanzar un valor asintótico. Si bien, el gobierno federal tiene actualmente por política no sembrar en cuerpos de agua naturales especies exóticas, éstas permanecen de siembras anteriores, o las siembran los gobiernos estatales o son de cultivos privados."