Notes on Occurrence of Young and Spawning of Scomberomorus sierra 
in the Eastern Pacific Ocean 
W. L. Klawe 1 
ABSTRACT: Young of Scomberomorus sierra are briefly described and compared 
with young of other scombroids and some other related families. At sizes of 30-50 
mm of total length young S. sierra can be distinguished from A. concolor on the 
basis of gill raker counts. 
From this study, based on the collection of larvae and juveniles of 5". sierra , it is 
evident that this species spawns near the coast over most of its distributional limits. 
Spawning off Mexico takes place in July through September and in lower latitudes 
from perhaps December through April. 
RESUMEN: Los juveniles de Scomberomorus sierra se describen brevemente y se 
comparan con los juveniles de otros escombroides y con algunas otras familias 
afines. Cuando alcanzan la longitud total de 30 a 50 mm los juveniles de S. sierra 
pueden ser distiguidos de los de S. concolor en base al recuento de las branqui- 
spinas. 
Es evidente, segun este estudio basado en la recoleccion de larvas y juveniles de 
S. sierra, que estas especies desovan cerca a la costa en la mayor parte de sus limites 
de distribucion. El desove f rente a Mexico toma lugar de julio a septiembre, y en 
las latitudes mas bajas probablemente de diciembre a abril. 
The genus Scomberomorus is represented in 
the eastern Pacific Ocean by two species, S. 
sierra and S. concolor, the sierra and the Mon- 
terey Spanish mackerel, respectively. The Span- 
ish name most commonly applied to both species 
is "sierra.” The distribution of S. sierra extends 
from California south to Peru and around the 
Galapagos Islands (Hildebrand, 1948; Roedel, 
1953; Berdegue, 1956; and Collette et al., 
1963). S. concolor ranges from California to 
perhaps as far south as the Gulf of Panama ; in 
the last century it was fished commercially in 
the waters off California, but at present is con- 
sidered to be rare there. The center of distribu- 
tion of S . concolor appears to be the Gulf of 
California (Fitch and Flechsing, 1949). The 
uncertainty concerning the distribution of S. 
concolor is due to its superficial resemblance to 
S. sierra. The number of gill rakers on the first 
gill arch is the main character which distin- 
guishes the two species from each other; counts 
for adults of the two species are: 
1 Inter- American Tropical Tuna Commission, La 
Jolla, California. Manuscript received June 9, 1965. 
SPECIES UPPER ARCH LOWER ARCH 
S. sierra 2-4 10-12 
S. concolor 5-9 15-20 
Little is known of the spawning and early 
life history of the two species, especially of S. 
concolor ; the only published information per- 
tains or appears to pertain to S. sierra. Accord- 
ing to Walford (1937), "sierra” in Mexican 
waters spawn probably in late spring or sum- 
mer. Eckles (1949) indicates that in the more 
southern waters, particularly off Costa Rica, the 
time of spawning is most likely January and 
February. Clemens (1956) substantiated Eck- 
les’ conclusion by collecting juveniles of S. 
sierra in the Gulf of Panama in early February. 
The closely related Atlantic species, S. macula- 
tus, spawns over a period of 6-10 weeks. The 
time of spawning is later in the northern parts 
of the Atlantic coast of the United States than 
in the southern parts (Earll, 1882). 
While collecting young stages of tunas by 
means of dip-netting under a night light from 
commercial fishing vessels and research ships in 
waters of the eastern Pacific Ocean, staff mem- 
445 
