Morphological descriptions of the early stages of spine and vertebral development in hatchery-reared larval and juvenile Atlantic halibut (Hippoglossus hippoglossus)

Larval and juvenile Atlantic halibut (Hippoglossus hippoglossus L.) were sampled from a commercial hatchery in order to classify and quantify skeletal abnormalities and meristic characters. Specimens were collected during two periods, July and December 2002, and were subdivided into length classes: fish < 3 cm in standard length (Ls) and fish > 3 cm in Ls. Using a whole mount bonestaining technique with Alizarin Red S, skeletal abnormalities were classified into 23 types, affecting the vertebrae centrums as well as the neural and hemal spines. Meristic characters included the total number of vertebrae and the number of vertebrae in the cephalic, prehemal, hemal, and caudal regions of the vertebral column. Fish sampled in July displayed more types of abnormalities and serious abnormalities such as lordosis and scoliosis. There were significant differences in the total number of vertebrae and number of vertebrae in the cephalic, pre-hemal, and caudal regions, although there was no significance in the number of vertebrae in the hemal region. The highest frequency of abnormalities occurred in the pre-hemal and hemal regions for each group. Results indicate that the types of abnormalities were more severe and varied from fish sampled in July, although the number of individuals afflicted with at least one type of abnormality did not decrease in fish sampled in December. These results provide information for further investigations into the nutritional and environmental factors causing bone deformities in cultured Atlantic halibut. (C) 2004 Elsevier B.V. All rights reserved.