Diet Components of Northern Shrimp Pandalus Borealis First Stage Larvae in the Northwest Gulf of St. Lawrence

Abstract

The objective of this study was to clarify the diet composition of the first stage larvae of northern shrimp Pandalus borealis during the spring period of high biological production in the Northwestern Gulf of St. Lawrence (NWGSL). Data collected in spring 2006 revealed that hatching of P. borealis larvae took place in late April and early May during a period characterized by a phytoplankton bloom (mainly species of the genus Chaetoceros) and by an abundance of early stages of mesozooplankton, which demonstrated the onset of secondary production at the sampling site. Gut content examination of stage I larvae sampled at the site and feeding experiments conducted at sea revealed that omnivorous feeding starts at hatching, but a first approximation based on the quantity of pigments present in the larvae suggest that zooplankton is more important than phytoplankton to meet the larvae’s energy needs. In addition, field observations of the degree of gut fullness and the low percentage (10%) of larvae with empty guts indicate a high feeding success. Hatching at the time of production of adequate prey could represent a major factor for larval northern shrimp survival in the NWGSL.