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SUMMARY: 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 nondestructive, fast and less expensive than genetic analysis, thus allowing screening of many individuals for traceability of fish.Keywords: scale shape, population discrimination, fish traceability, Lutjanidae, Mexican Pacific, geometric morphometrics. RESUMEN: ConeCtividad poblaCional entre variantes geográfiCas de lutjanidae (pisCes) en las Costas del paCífiCo mexiCano a través del reConoCimiento de la forma de las esCamas. -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. p...

The tropical eastern Pacific (TEP) is a highly dynamic region and a model system to study how habitat discontinuities affect the distribution of shorefishes, particularly for species that display ontogenetic habitat shifts, including snappers (Lutjanidae). To evaluate the genetic structure of the Pacific red snapper (Lutjanus peru) and the yellow snapper (Lutjanus argentiventris) throughout their distribution range along the TEP, 13 and 11 microsatellite loci were analysed, respectively. The genetic diversity of L. peru (N = 446) and L. argentiventris (N = 170) was evaluated in 10 and 5 localities, respectively, showing slightly higher but non-significant values in the Gulf of California for both species. The genetic structure analysis identified the presence of significant genetic structure in both species, but the locations of the identified barriers for the gene flow differed between species. The principal driver for the genetic structure at large scales >2500 km was isolation by distance. At smaller scales (<250 km), the habitat discontinuity for juveniles and adults and the environmental differences throughout the distribution range represented potential barriers to gene flow between populations for both species.

Reproduction of Mugil cephalus of the Pacific coast of Mexico was studied. Fish were captured with gill nets and cast nets; they are a common low priced product for local consumption. The study of the reproduction period and ages of first maturity helps manage the fishery. Fish were obtained from local commercial fishery from August to December 2007, January to March 2008 and November 2012 to October 2013. Size and weight, sex and gonad maturity were registered. The male:female ratio was 0.88:1. Mature organisms occurred all year round. Sexual maturation (L 50 ) of males and females was observed at a mean size of 34.0 cm in males (4.64 years of age) and 35.0 cm in females (4.98 years of age). First maturity length (L 25 ) was both 30.0 cm in males and females corresponding to 3.4 years of age in both cases. The allometric relationship with the hepatosomatic index was LW=4.00·10 −3 · TL 2.771

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