Observations on the growth of the sculptured shrimp Sclerocrangon boreas (Decapoda: caridea)

Abstract

Little is known of the growth of the sculptured shrimp Sclerocrangon boreas, a remarkable member of arctic and subarctic marine shelf communities. We determined the length-weight relationship, abdomen allometry, and size structure of shrimp in a population of the Gulf of Saint Lawrence, eastern Canada. We also reared shrimp for up to 3.5 years to measure their growth. The presence of very small immature females in the wild population indicates that the sculptured shrimp is not obligatorily a protandric hermaphrodite, if at all. Females grow faster, reach a greater size, and live longer than males. Males may be ≥ 4 years old at 17 mm cephalothorax length (CL) and females ≥ 6 years old at 29 mm CL. Ovigerous females have a broader abdomen with longer pleopod setae than similarly-sized immature females. After releasing their progeny, some females may molt and grow in length but revert to a condition of narrow abdomen and short pleopod setae, and then molt again to a condition of broad abdomen with long pleopod setae. This finding and demographic data suggest that some females are alternate-year spawners. Other females did not molt for ≥ 2 years and may spawn in successive years.