78 
Abstract — Jumbo squid (Dosidicus 
gigas) and purpleback squid ( Sthe - 
noteuthis oualaniensis) (Teuthida: 
Ommastrephidae) are thought to 
spawn in the eastern tropical Pa- 
cific. We used 10 years of plankton 
tow and oceanographic data collect- 
ed in this region to examine the re- 
productive habits of these 2 ecologi- 
cally important squid. Paralarvae of 
jumbo squid and purpleback squid 
were found in 781 of 1438 plankton 
samples from surface and oblique 
tows conducted by the Southwest 
Fisheries Science Center (NOAA) in 
the eastern tropical Pacific over the 
8-year period of 1998-2006. Paralar- 
vae were far more abundant in sur- 
face tows (maximum: 1588 individu- 
als) than in oblique tows (maximum: 
64 individuals). A generalized linear 
model analysis revealed sea-surface 
temperature as the strongest envi- 
ronmental predictor of paralarval 
presence in both surface and oblique 
tows; the likelihood of paralarval 
presence increases with increasing 
temperature. We used molecular 
techniques to identify paralarvae 
from 37 oblique tows to species level 
and found that, the purpleback squid 
was more abundant than the jumbo 
squid (81 versus 16 individuals). 
Manuscript submitted 18 April 2012. 
Manuscript accepted 27 November 2012. 
Fish. Bull. 111:78-89 (2013). 
doi:10.7755/FB. 11 1.1.7 
The views and opinions expressed 
or implied in this article are those of the 
author (or authors) and do not necessar- 
ily reflect the position of the National 
Marine Fisheries Service, NOAA. 
Distribution of ommastrephid paralarvae in the 
eastern tropical Pacific 
Danna J. Staaf (contact author ) 1 
Jessica V. Redfern 2 
William F. Gilly 1 
William Watson 2 
Lisa T. Ballance 2 
Email address for contact author: danna|oy@gmail 
1 Hopkins Marine Station of Stanford University 
120 Oceanview Blvd 
Pacific Grove, California 93950 
2 Southwest Fisheries Science Center 
National Marine Fisheries Service, NOAA 
8901 La Jolla Shores Dr. 
La Jolla. California 92037 
Adult squid of the oceanic family 
Ommastrephidae are active general- 
ist predators and key prey for a wide 
variety of marine fishes, birds, and 
mammals. They are also the primary 
targets of the world’s larger squid 
fisheries (Nigmatullin et al., 2001; 
Markaida et ah, 2005; FAO, 2011). 
Many questions remain unanswered 
about the reproduction and early life 
history of these oceanic squid (Young 
et ah, 1985; Boletzky, 2003). Logisti- 
cal challenges impede direct obser- 
vation of reproduction and develop- 
ment in the wild, but the collection 
of paralarvae in net tows often can 
be used to elucidate ommastrephid 
spawning grounds and the habitat 
needs of early life stages (e.g., Oku- 
tani and McGowan, 1969; Zeidberg 
and Hamner, 2002). 
Two ommastrephid species that 
reproduce in the eastern Pacific are 
Dosidicus gigas, the jumbo or Hum- 
boldt squid, and Sthenoteuthis oual- 
aniensis, the purpleback squid (Vec- 
chione, 1999). The jumbo squid is 
currently the target of the world’s 
largest squid fishery (628,579 t in 
2009 [FAO, 2011]), and commercial 
interest in purpleback squid is grow- 
ing (Zuyev et ah, 2002; Xinjun et ah, 
2007). The adult ranges of these 2 
species overlap in the eastern tropi- 
cal and subtropical Pacific (Roper et 
com 
ah, 1984), but the location and ex- 
tent of spawning grounds of either 
species over this large region are 
not well established. Paralarvae of 
these species cannot be reliably dis- 
tinguished morphologically; molecu- 
lar techniques must be used (Gilly 
et ah, 2006; Ramos-Castillejos et ah, 
2010). When molecular identification 
is not possible because of formalin 
preservation or other limitations, 
paralarvae in this broad geographic 
region are generally assigned to the 
“SD complex” IS. oualaniensis and D. 
gigas [Vecchione, 1999]). 
Ommastrephid paralarvae are 
relatively rare off California (e.g., 
Okutani and McGowan, 1969; Wat- 
son and Manion, 2011), and none 
have been attributed to jumbo squid 
or purpleback squid. Both species, 
however, have been identified off the 
Pacific coast of the Baja California 
Peninsula (Hernandez-Rivas et ah 1 ; 
Ramos-Castillejos et ah, 2010). With- 
1 Hernandez-Rivas, M. E., R. De Silva- 
Davila, S. Camarillo-Coop, J. Grana- 
dores-Amores, and R. Durazo. 2007. 
Ommastrephid paralarvae during 1997- 
1999 IMECOCAL cruises. Abstract in 
California Cooperative Oceanic Fisheries 
Investigations Annual Conference 2007, 
Program and Abstracts; San Diego, CA, 
2-28 November, p. 41. Calif. Coop. 
Oceanic Fish. Invest., La Jolla, CA. 
