562 
Age, growth, mortality, and 
population characteristics of the 
Pacific red snapper, Lutjanus pern, 
off the southeast coast of 
Baja California, Mexico 
Axayacatl Rocha-Olivares 
Universidad Autonoma de Baja California Sur 
Departamento de Biologia Marina 
Apartado Postal 1 9-B, La Paz 
Baja California Sur, 23080 Mexico 
Present address: Department of Biological Sciences, 508 Life Sciences Building 
Louisiana State University, Baton Rouge, Louisiana 70803-1715 
E-mail address: arocha@lsu.edu 
Abstract .—Pacific red snapper, 
Lutjanus peru, collected from commer- 
cial hook-and-line gear and shrimp 
trawls off the southeast coast of Baja 
California Sur, Mexico, were aged by 
using scales and otoliths (whole-otolith 
and sectioned-otolith readings). Com- 
parison of ages determined from these 
structures revealed that scales tend to 
underestimate ages beyond 5 years, of- 
ten by more than 1 year, and that they 
are the least precise structures for age- 
ing. Sectioned otoliths gave greater es- 
timates of age than whole-otolith 
counts (mean differences <1 yr) and 
were the most precise structure. The 
von Bertalanffy growth function de- 
scribed L. peru growth satisfactorily 
with length-at-age determined from 
whole otoliths and sectioned otoliths. 
Parameters for the entire population 
were L x = 97.32 cm, K = 0.1111/yr, f 0 = 
-0.316 yr ( rz = 1 180 ). No significant dif- 
ferences in length-at-age were found be- 
tween sexes. The largest individual was 
a 31-year-old 99.2-cm-TL male, consti- 
tuting a maximum age, and length 
record for this species. A multiple re- 
gression model of whole-otolith age as 
a function of otolith and fish measure- 
ments provided satisfactory results. 
Total mortality rates were significantly 
lower for females (Z=0.282/yr) than for 
males (Z=0.366/yr). 
Manuscript accepted 24 November 1997. 
Fishery Bulletin 96:562-574 (1998). 
The Pacific red snapper, Lutjanus 
peru (Nichols and Murphy), known 
as “huachinango” in Mexico, is dis- 
tributed throughout the lower Gulf 
of California to Peru and found in 
offshore schools over rocky bottoms 
to depths exceeding 100 m. It is a 
commercially important species in 
Mexico as well as in Central and 
South America (Thomson et ah, 
1987; Gutierrez Vargas, 1990; Ra- 
mirez Rodriguez and Rodriguez 
Medrano, 1990). 
Lutjanus peru is fished in most 
Mexican states along the Pacific 
coast. The highly valued product is 
generally marketed whole and 
transported to inland cities, or oc- 
casionally exported. Nationwide, it 
shares a market with its congener, 
the Gulf of Mexico red snapper 
Lutjanus campechanus Poey. From 
1980 to 1988, the reported catches 
of both species averaged 6556 met- 
ric tons (t) per year (SD 1290 t/yr), 
of which 56% originated in the Pa- 
cific. 1 In Baja California Sur, Pacific 
red snapper is fished on a small 
artisanal scale; near Cerralvo Is- 
land, L. peru ranks within the six 
most important exploited finfishes 
(Fig. 1) (Ramirez Rodriguez and 
Rodriguez Medrano, 1990). As is the 
case with other snappers, juveniles 
of this species aggregate over soft 
bottoms where they are caught as 
bycatch during shrimp trawling ac- 
tivities (Van Der Heiden, 1985; 
author’s personal observations). 
Information on the biology of L. 
peru is limited despite its ecologi- 
cal and commercial importance. 
Gorelova (1979) performed feeding 
experiments on juvenile L. peru 
caught off the coast of Peru, whereas 
Ruiz Santos (1983) studied the re- 
productive biology of the species off 
the southwest coast of Mexico and 
Ruiz and Madrid ( 1992 ) studied the 
biology of a parasitic isopod and its 
effects on L. peru hosts off Michoacan. 
With the exception of Rocha Olivares 
and Gomez Munoz (1993), age and 
growth of the Pacific red snapper 
have been estimated either from 
scales in Mexico (Castro, 1981; Ruiz 
Luna et al., 1985; Aguilar Salazar, 
1986) or from length-frequency dis- 
tributions in Costa Rica (Gutierrez 
Vargas, 1990). The use of scales, 
however, may result in less than 
accurate age estimates for some 
1 Anuarios Estadisticos de Pesca, Secretaria 
de Medio Ambiente Recursos Naturales y 
Pesca. Av. Progreso Num. 5, Colonia Del 
Carmen, Coyoacan. Delegacion Coyoacan 
04110, Mexico, D.F. 
