Earl G. Dawe

A review of factors contributing to the decline of Newfoundland and Labrador snow crab ( Chionoecetes opilio )

Abstract The Newfoundland and Labrador (NL) snow crab resource, presently the basis of the most important commercial fishery in the region, is in decline. Short-, mid-, and long-term recruitment prospects are deemed poor in most areas. Fishery declines have been most apparent in the north, beginning in the mid- to late 2000s, but are expected to begin in the more productive southern areas in the near future. A multitude of emergent theories to explain the resource decline have been hypothesized as contributing factors, including fishing, trawling impacts, seismic activities, disease, predation, and increasing temperature. This study comprehensively reviews and qualitatively relates the results of recent research and literature on each of these factors. We find that several factors may be contributing to a lack of recruitment in the stock, but diminishing productivity resulting from a warming oceanographic regime is the primary cause of the resource decline. Further, we postulate that trends occurring in the snow crab stock are indicative of a broader-scale ecological regime shift occurring along the NL shelf.

Protistan parasites as mortality drivers in cold water crab fisheries

From a historical perspective, several protistan taxa, including the recently re-aligned Microsporidia, have been associated with or identified as causes of mortalities in crustacean populations. Depending upon the host species, associated protistan prevalences could be as low as 5% or approach 100%. It has generally been assumed that reported prevalences translated directly into significant mortalities that could impact the distribution and abundance of affected populations. However, this assumption may be incorrect especially when the dynamics of host-pathogen-environment interactions are not entirely understood. We will discuss the presumed impact of several protistan pathogens on temperate and cold water commercial crab species. By using selected examples such as a ciliate in the Dungeness crab (Cancer magister) and Hematodinium sp. infections in North Pacific crabs, we will attempt to contrast differences between prevalence and mortality, acute and chronic infections/mortalities, age or size selectivity of affected population, and geographically restricted and widespread epizootics. We will also briefly discuss the potential impact of environmental changes such as climate change and ocean acidification on both host and protistan pathogen.

A Compilation of Recent Records of the Giant Squid, Architeuthis dux (Steenstrup, 1857) (Cephalopoda) from the Western North Atlantic Ocean, Newfoundland to the Gulf of Mexico

Abstract This report provides information on 28 specimens of the giant squid, Architeuthis dux (Steenstrup 1857), discovered in the western North Atlantic Ocean between Newfoundland and the Gulf of Mexico. Some specimens have been reported in the press or popular literature, but others are recorded herein for the first time. Nominal architeuthid species are provided as well as tables listing repositories of types of nominal species, and repositories of non-type specimens from the study area. An extensive list of references of pertinent regional literature is provided, and recommendations for fixation and preservation are described.

Northern Range Extension of the Gladiatior Box Crab, Acanthocarpus alexandri Stimpson, 1871 (Decapoda: Brachyura: Calappidae) in the Northwest Atlantic

Abstract A specimen of a gladiator box crab, Acanthocarpus alexandri Stimpson, 1871, was captured off the northeast coast of Newfoundland during June 2009. This is the first report of the species in Canadian Atlantic waters, and represents a major northern expansion in the distributional range by approximately 800-900 kilometres. The known distribution of this western Atlantic species now extends from Newfoundland to Brazil, encompassing tropical, temperate, and sub-arctic marine ecosystems.