Impact of temperature on
juvenile growth and age at first egg-laying of the Pacific reef squid Sepioteuthis
lessoniana reared in captivity
J. W. Forsythe, L. S. Walsh, P. E. Turk, P. G.
Lee-2001
Marine Biology, 138 (1): 103-112
Abstract:
Cephalopod mollusks exhibit highly plastic life cycle
traits influenced primarily by the interactive effects of food availability,
light cycle and temperature, with the latter perhaps the most influential.
Hatchlings of the tropical reef squid Sepioteuthis lessoniana were
hatched from field-collected eggs in the laboratory and cultured at
different temperatures to evaluate the effect of temperature on growth
rates. All groups showed rapid, sustained growth rates from hatching to a
size of 10-25 g. Beyond this size range, growth was slower and not clearly
exponential in form. Growth rate was closely linked to temperature. Squids
grown at approximately 27 °C attained a size of 10 g in as little as 45
days at sustained growth rates of 12.2% body weight day-1 (%bw
day-1), while squids cultured at 20 °C required almost 100 days
to attain the same size at rates of 5.7%bw day-1. At an age of 55
days and approximately 1 g body weight, juvenile squids cultured at 20 °C
were able to accelerate growth rates from 5.7%bw day-1 to over
12%bw day-1 when temperature was raised to 27 °C. They
maintained this growth rate to a size of about 10 g and an age of at least
75 days post-hatching, indicating that body size and not age is the limiting
factor for this rapid post-hatching growth. By comparison, conspecifics
cultured near 27 °C from hatching had shifted out of the rapid
post-hatching growth phase by day 50 at sizes between 10 and 50 g. The
hatchlings from temperate to subtropical Japan had consistently higher
growth rates at comparable temperatures than hatchlings from tropical
Okinawa. When plotted as growth rate versus temperature, the Japanese group
had a clearly higher slope to the relationship than the tropical
populations, equivalent to a 2%bw day-1 difference in growth rate
at 25 °C. Age at first egg-laying was decreased at higher culture
temperatures; however, overall life span was not.
(National Resource Center for Cephalopods, Marine
Biomedical Institute, University of Texas Medical Branch, Galveston, TX
77555-1069, USA Fax: +1-409-7726993 e-mail: jwforsyt@utmb.edu)