Meeting Abstract
The Northern spot prawn (Pandalus platyceros) is a commercially important shrimp species in Southeast Alaska that has an interesting life history which presents challenges for its effective management. P. platyceros is protandric and demonstrates sequential hermaphroditism. As this shrimp matures and grows, it transforms from a small functional male to a much larger functional female. During its life history, the male shrimp undergoes at least one transitional phase during which it is not known if it functions as a male or a female. Our study objectives were to identify each life history stage through examination of the 2nd pair of pleopods and determine the life history specific size range of P. platyceros. A second goal was to investigate the reproductive biology of female shrimp to determine whether females produced multiple clutches or if they are semelparous. We measured the gonadosomatic index (GSI) of a subset of the collected females. Male (n=46), transitional (n=25), ovigerous females (101), and non-ovigerous females (n=17) were collected in Southeast Alaska in February and maintained at the University of Alaska Southeast marine laboratory in flow-through seawater. Male carapace length (CL; 34.6 ± 4.4 mm) was less than transitionals (40.3 ± 3.2 mm) and females (45.3 ± 4.1 mm). Ovigerous females hatched beginning in late April and hatching times averaged 2 weeks. Females molted after hatching but did not mate in the lab. Non-ovigerous females demonstrated a greater GSI than the ovigerous females (1.75 ± 1.5 verses 0.62 ± 0.145) and only three ovigerous females extruded eggs after molting. These observations support female P. platyceros being able to develop multiple clutches over their lifetime. Our studies show that the reproductive biology of this cold water species is complex and that females may produce clutches every other year.
