Search

Oreochromis aureus es un importante recurso pesquero en el embalse, por lo cual se realizó un estudio sobre su edad y crecimiento desde noviembre del 2006 a septiembre del 2007. Se realizaron muestreos bimensuales con redes agalleras de varios tamaños de luz de malla, y también se colectaron peces de la captura comercial. Se midió la longitud total (Lt), el peso total (Pt), el sexo y la madurez gonádica. La edad se determinó mediante lecturas de marcas de crecimiento en escamas y su validación se realizó mediante el índice marginal e índice gonadosomático. Se colectaron 384 peces, las tallas y pesos variaron de 125 a 345mm y de 40 a 671g, respectivamente. El crecimiento en longitud y peso se describe mediante las ecuaciones de von Bertalanffy: Lt = 416 [1-e-0.3682 (t+0.4975)] y Pt = 1323[1- e-0.3682(t+0.4975)]]3.0652. Se determinaron dos marcas de crecimiento durante el año. Estas fueron asociadas con factores metabólicos y medioambientales como la reproducción y la oscilación de temperatura, combinada con procesos de mezcla y disminución de los niveles del agua del embalse.Age and growth of Oreochromis aureus (Pisces: Cichlidae) in Sanalona Reservoir, Sinaloa, Mexico. Oreochromis aureus is an important fishing resource in this reservoir but little biological information is available for management purposes. To study its age and growth in the site, we obtained samples using gill nets of six mesh sizes, and collecting fish from commercial catches, on a bimonthly basis, from November 2006 to September 2007. Total length (Lt), total weight (Pt), sex and gonadosomatic maturity were analyzed. Age determination was done by readings of scale growth marks, and its validation was made by the marginal and gonadosomatic index. A total of 384 fish were collected. Length and weight varied from 125 to 345mm and from 40 to 671g, respectively. Growth in length and weight are described by the following von Bertalanffy equations: Lt=416 [1-e-0.3682 (t+0.4975)] and Pt=1323[1-e -0.3682(t+0.4975)]]3.0652. Two growth marks per year were registered, these were associated to metabolic and environmental factors like reproduction and temperature. Rev. Biol. Trop. 58 (1): 325-338. Epub 2010 March 01.

Micropterus salmoides is an important fish species for sport fishing activities, condition that has promoted its introduction to different reservoirs in Mexico and worldwide. With the aim to improve its fisheries management, this research dealt with some reproductive aspects of this species in the Gustavo Diaz Ordaz reservoir, where it was studied from August 2008 through March 2011. To this end, we obtained 938 specimens, with gillnets of different sizes, to determine their total length (Lt, in cm), weight (Pt, in g), sex, gonadosomatic index, condition factor, fecundity and size at first maturity. Lt and Pt ranged from 15.9 to 63cm (37.4±78.0) and 57 to 4 431g (731.7±619.0), respectively. The Pt-Lt relationship showed a positive allometric growth, with no significant difference between males and females (F=0.9955, p=0.3187). The male: female ratio obtained was 1:0.83. Mass spawning lasted from December to April. Size at first maturity was 33.7cm and average fecundity was 32 294±12 878.7 oocytes/female. The gonadosomatic index was low from May through November, and increased between January and March. The condition factor was high before the spawning season and decreased after the reproductive period. We recommend a fishing ban from January to March, and to allow the capture size between 33 and 40cm.

Micropterus salmoides is an important fish species for sport fishing activities, condition that has promoted its introduction to different reservoirs in Mexico and worldwide. With the aim to improve its fisheries management, this research dealt with some reproductive aspects of this species in the Gustavo Diaz Ordaz reservoir, where it was studied from August 2008 through March 2011. To this end, we obtained 938 specimens, with gillnets of different sizes, to determine their total length (Lt, in cm), weight (Pt, in g), sex, gonadosomatic index, condition factor, fecundity and size at first maturity. Lt and Pt ranged from 15.9 to 63 cm (37.4 +/- 78.0) and 57 to 4431 g (731.7 +/- 619.0), respectively. The Pt-Lt relationship showed a positive allometric growth, with no significant difference between males and females (F = 0.9955, p = 0.3187). The male: female ratio obtained was 1:0.83. Mass spawning lasted from December to April. Size at first maturity was 33.7 cm and average fecundity was 32294 +/- 12878.7 oocytes/female. The gonadosomatic index was low from May through November, and increased between January and March. The condition factor was high before the spawning season and decreased after the reproductive period. We recommend a fishing ban from January to March, and to allow the capture size between 33 and 40 cm.

Oreochromis aureus is an important fishing resource in this reservoir but little biological information is available for management purposes. To study its age and growth in the site, we obtained samples using gill nets of six mesh sizes, and collecting fish from commercial catches, on a bimonthly basis, from November 2006 to September 2007. Total length (Lt), total weight (Pt), sex and gonadosomatic maturity were analyzed. Age determination was done by readings of scale growth marks, and its validation was made by the marginal and gonadosomatic index. A total of 384 fish were collected. Length and weight varied from 125 to 345 mm and from 40 to 671 g, respectively. Growth in length and weight are described by the following von Bertalanffy equations: Lt=416 [1-e(-0.3682)(t+0.4975)] and Pt=1323 [1-e(-0.3682(t+0.4975)](3.0652). Two growth marks per year were registered, these were associated to metabolic and environmental factors like reproduction and temperature.

Some growth and reproduction parameters of the population of the shrimp Atya margaritacea in Presidio River (Sinaloa, NW Mexico) were studied using 542 organisms collected with a Surber net in five sampling locations distributed from mid- to low river. Total lengths and gross weights ranged from 15 to 96 mm and 0.1 to 25.2 g. The male:female ratio was 1.96:1 and males had larger sizes and weights. The relations of total length (Lt) to gross weight (Pt) were Pt = 1.02 x 10(-5) (Lt)32089 for males and Pt = 2.29 x 10(-5) (Lt)3.0159 for females. Growth in males was positively allometric whereas in females it was isometric. The regressions between total lengths and cephalothorax (Lc) were Log Lc = 1.1118 (Log Lt)- 0.6087 for males and Log Lc = 0.9945 (Log Lt)- 0.4321 for females. The relative growth between these body parts was allometrically positive in males and isometric in females; this result indicates a clear sexual dimorphism. Ovigerous females appeared in the rainy season (July to November). The absolute fecundity ranged from 1860 to 22400 eggs in females of 43 to 59 mm in length and 1.9 to 6.0 g in weight. The equations relating the number of eggs to length and weight were Fec = 8.3 x 10(-7) (Lt)5.8053 and Fec = 732 (Pt)1.836 respectively.