地理ジャーナルと自然災害
オープンアクセス

概要

Reproduction of Mugil cephalus (Percoidei: Mugilidae) off the Central Mexican Pacific Coast

Elaine Espino-Barr, Manuel Gallardo-Cabello, Marcos Puente-Gómez and Arturo Garcia-Boa

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 (L₅₀) 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 (L₂₅) 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 · TL2.771 (r²=0.849). Condition factor indexes of Clark and Safran EW showed a maximum increment during June, August and December; Fulton and Safran TW in July and September to November. The gonadosomatic index showed its highest values from November to January. The hepatosomatic index reached its maximum values in June, July and August. The gastric repletion index reached its highest values in June, February and October. The mean oocytes diameter was 0.38 mm (range 0.22 to 0.52 mm, standard deviation=0.13). Fecundity ranged from 1’422,076 to 1’747,736 oocytes in females between ages 3 and 12 years old, and mean relative fecundity was 2,830 oocytes·g^-1 (1,500 to 2,900 oocytes·g^-1). This study is the base line for the fishery management of M. cephalus in Central Mexican Pacific, where the main regulations need information on the first maturity size and reproductive season.