period water conditions were 13.8°C, 35.0 ppt, pH 

 8.01, and NH4-N was <0.01 mg/L. The squid were 

 initially fed three to seven times daily on assorted 

 zooplankton that consisted mainly of copepods 

 (0.5-2.5 mm body length). Subsequently, Palaemo- 

 netes sp. shrimp larvae, Penaeus sp. shrimp larvae, 

 Mysidopsis sp. mysids, and fish larvae were offered. 

 Once the squid attained 20 mm mantle length (ML), 

 they were transferred to a 9,950 L raceway culture 

 tank (RW) and their diet consisted of Palaemonetes 

 sp. adults and small fish {Menidia sp.). 



Results 



Water quality data are listed in Table 1. Mortality 

 was high during the first week despite many obser- 

 vations of active feeding by the hatchlings. The ini- 

 tial estimated population was 6,673 squid and 99% 



Table 1 .—Water quality of circular culture tank (CT) and race- 

 way culture tank (RW) systems for Loligo pealei. 



CT system 

 (days 1-124) 



RW system 

 (days 124-171) 



of these died by day 5. By day 13 only three squid 

 were alive and these survived to days 23, 130, and 

 172. 



The types of food organisms offered to the squid 

 and the periods they were fed are summarized in 

 Figure 1. From days 1 to 57, the squid were fed wild- 

 caught zooplankton (collected near shore and in the 

 bays near Galveston Island). The copepods Centro- 

 pages velificatus, Temora turbinata, Eucalanus 

 pileatus, and Labidocera aestiva were the predomi- 

 nant species in the plankton, while crab zoea, 

 sergestid shrimps, cladocerans, chaetognaths, and 

 fish larvae were less common. We estimate plankton 

 density at about 40/L during this period. There was 

 certainly ample food available and feeding (mostly 

 on copepods) was seen often from day 1 onward. 

 Beginning day 22, palaemonid shrimp larvae (2-4 

 mm) were added to the tank and captured by squid. 

 The squid were first able to capture mysid shrimp 

 (2-8 mm) on day 51, and by day 57 benthic crusta- 

 ceans (mainly Mysidopsis sp.) replaced zooplankton 

 as the main diet. During this period food organism 

 densities fluctuated between 2 and 10/L. As late as 

 44 d posthatching, squid (4-5 mm ML) were still seen 

 eating copepods {Labidocera aestiva) as small as 1-2 

 mm long even with larger crustacean food available. 

 After the transfer to the RW system, only benthic 

 adult palaemonid shrimp and occasionally fishes 

 were fed (<0.15/L). 



The squid hatched at a mean size of 1.84 mm ML. 

 The largest squid lived 172 d and attained a length 

 of 35.4 mm ML and weighed 2.77 g. This female had 

 a nidamental gland of 5.15 mm, indicating that the 



z: 



LJU 



_l 



LU 



40r 



30 

 20 

 10 



10 



ZOOPLANKTON 

 PENAEID LARVAE 

 MYSIDS 



PALAEMONID LARVAE 

 PALAEMONID ADULTS 

 FISHES 



L VULGARIS L OPALESCENS L. PEALEI 



IVIL= 3 296° 02281/ /ML= 2 126° 0255'/ ML = 1 30eO°209, 



• DEAD L PEALEI 

 o PHOTO L. PEALEI 



J 1 l_ 



_J I I I 



50 100 



AGE (days) 



150 



200 



Figure 1.— Feeding and growth in Loligo pealei. Laboratory growth oi Loligo vulgaris (Turk et al. 1985) 

 and L. opalescens (Yang et al. 1986) is provided for comparison. 



164 



