Hematodinium is a parasitic dinoflagellate of numerous crustacean species, including the economically important Atlantic snow crab, Chionoecetes opilio. The parasite was cultured in vitro in modified Nephrops medium at 0°C and a partial characterization of the life stages was accomplished using light and transmission electron microscopy (TEM). In haemolymph from heavily infected snow crabs two life stages were detected; amoeboid trophonts and sporonts. During in vitro cultivation, several Hematodinium sp. life stages were observed: trophonts, clump colonies, sporonts, arachnoid sporonts, sporoblasts and dinospores. Cultures initiated with sporonts progressed to motile dinospores; however, those initiated with amoeboid trophonts proliferated, but did not progress or formed schizont-like stages which were senescent artefacts. Plasmodial stages were associated with both trophonts and sporonts and could be differentiated by the presence of trichocysts on TEM. Macrodinospores were observed but not microdinospores; likely due to the low number of Hematodinium sp. cultures that progressed to the dinospore stage. No early life stages including motile filamentous trophonts or gorgonlocks were observed as previously noted in Hematodinium spp. from other crustacean hosts. All Hematodinium sp. life stages contained autofluorescent, membrane-bound electron dense granules that appeared to degranulate or be expelled from the cell during in vitro cultivation.

This paper traces the evolution of snow crab fisheries science and its impact on the management of the southern Gulf of St. Lawrence snow crab (Chionoecetes opilio) fishery. This currently lucrative fishery (estimated landed value of more than 125 million Canadian dollars in 1994) has experienced the traditional rises and falls of most fisheries and the resulting socio-economic consequences and sometimes strained relations between the industry and the fisheries management agency, in this case the Canada Department of Fisheries and Oceans (DFO). Of note at this time is the remarkable degree of cooperation that has developed between the industry and DFO since the stock has drastically decreased (1987–1989). Since then the stock has been recovering steadily and is also better managed. The reasons for this are four-fold: (1) arecruitment pulse of small-sized crab occurred in 1988–1989; (2) substantial advances in the understanding of the complex biology of snow crab and the development of an accurate, reliable stock assessment methodology together have provided consistent, reliable and credible advice for forecasting the amount and geographic distribution of exploitable biomass for the upcoming fishing season; (3) the industry leaders worked very hard with their associations to convince fishers that their fishery was in peril and that close cooperation with DFO was the key for the future; (4) the industry and DFO (fisheries biologists and managers) worked as partners to develop a management approach based upon scientific advice to climb out of the trough. The paper also outlines the conundrum that fisheries managers currently face resulting from a combination of a moratorium of the entire Gulf of St. Lawrence groundfish fishery, the consequent pressure from displaced groundfish fishers to enter the lucrative snow crab fishery and an optimistic shortterm but pessimistic longer term forecast regarding snow crab abundance: do we redistribute the wealth; if so among whom and how and for how long?

Osmoregulation and salinity tolerance were studied in zoeae 1 and instar IX juveniles of Chionoecetes opilio. In zoeae 1, the lower and upper lethal salinities for 50% of the animals (LS 50) at 14 °C were about 10 and 42‰ at 24 h, 18 and 41‰ at 48 h, 25 and 38‰ at 96 h. In juveniles, the approximate 48 h LS 50 s at 6 °C were 13.5 and 46‰. Both developmental stages are able to withstand relatively ample but brief variations of salinity. Their short-term euryhalinity is discussed in relation to the salinity of their habitat. Zoeae were hyper-osmoconformers. Juveniles were osmoconformers and isoionic to the external medium except for Mg++ which was hypo-regulated. Isosmotic and isoionic regulation in post-metamorphic stages are presumably an attribute of the family Majidae. The pattern of osmoregulation in zoeae 1 and juveniles relate C. opilio to the first of three groups of species previously characterized by their pattern of ontogeny of osmoregulation.