Depth distribution, habitat associations, and differential growth of newly settled southern tanner crab (chionoecetes bairdi) in embayments around Kodiak Island, Alaska

Abstract

We examined depth distribution, habitat association, and growth of newly settled southern Tanner crab (Chionoecetes bairdi) at 4 sites around the eastern end of Kodiak Island, Alaska, during 2010 and 2011. Settlement was from April through July, and crab density peaked during May–July, at 10 crabs/m 2 in 2010 and 2.3 crabs/m 2 in 2011. By the end of August most crabs had progressed through 3–5 molt stages (instars). An association between crabs and tubes of the ampharetid polychaete Sabellides sibirica was observed in 2010, but it was not seen in 2011 when both crabs and worms were less abundant. Crabs in protected embay-ments were larger in August than crabs at open coastal sites. Crabs at protected sites were also found in shallower water than at open coastal sites—a difference that may have exposed them to higher ambient water temperature and may have accelerated their growth. Accelerated growth may in turn result in earlier maturation. Southern Tanner crabs probably settle over a wide range of depths, but shallow embayments (depths <50 m) may play a disproportionately large role in providing recruits to the adult population, due to accelerated crab growth and survival.