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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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Yellowfin Mojarra Gerres cinereus (Walbaum, 1792) off the Mexican Pacific coast is a popular low-cost species, which is caught with gill and cast nets. Knowing breeding seasons, gonadal maturity, fecundity and size at sexual maturity is necessary for fishery management. Samples were obtained from April 2010 to November 2011. Size, sex and gonad maturity were recorded, while the gonadosomatic index and the fecundity and condition factors were calculated using the gravimetric method. To calculate this information by age, growth parameters previously published were used. The female:male ratio was 1:1.024. Mature females were observed year round with two major peaks during July and October. Sexual maturation (L 0.5 ) of males and females was 16.40 cm and 20.20 cm, respectively, corresponding to one-year old organisms. First maturity length (L 0.25 ) was 15.80 cm in males and 16.50 cm in females. The hepatosomatic index vs length was LW = 2.00·10 -6 ·TL 4.213 , resulting in a positive allometric relationship. Condition factor indexes increased during February and September. Average oocyte diameter was 0.31 mm (0.15 to 0.45 mm). Fecundity ranged from 37,784 to 1,746,510 oocytes in females from one to seven years of age, and mean relative fecundity was 1332 oocytes·g -1 (294 to 4,430 oocytes·g -1 ). G. cinereus has an early sexual maturity, reproduces once or twice a year and has a high fecundity rate, which allows it to be caught all year round, if caught after the first maturity length.

Resumen.-Se estudian algunos aspectos biológicos de Lutjanus peru (Pisces: Lutjanidae) recolectado en la Bahía Bufadero, Michoacán, México. El análisis de escamas permitió identificar cuatro anillos de crecimiento, valores similares fueron obtenidos por medio de los estimadores de densidad de Kernel. Los resultados de la ecuación de crecimiento de von Bertalanffy obtenidos por el método lineal simple fueron: L ∞ = 81,12 cm, W ∞ = 4.839 g, K= 0,24 años-1 y t o =-0,39 años. Los máximos valores del índice de repleción y del factor de condición ocurren durante los meses de febrero, abril y junio. Los periodos de máxima reproducción ocurren durante los meses de febrero y agosto. Los periodos de reclutamiento al área son de enero a julio para los nacidos en agosto, y de agosto a diciembre para los nacidos en febrero. El tamaño de reclutamiento al arte de pesca es de 18 cm. El índice gonadosomático muestra una relación inversamente proporcional en relación al índice hepatosomático. La longitud corporal de L. peru en su primera madurez sexual es de 25,45 cm y su longevidad es de 12 años. El 65,84% de la pesca en Bahía Bufadero es de organismos sexualmente inmaduros, por lo que se propone como talla mínima de captura una longitud de 45 cm (edad 3 años) y un periodo de veda para agosto y septiembre.

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