Interannual Variation in the Population Dynamics of Juveniles of the Deep-Sea Crab Chionoecetes tanneri

Overview & Synopsis

Understanding the population dynamics of commercially fished deep-sea species, on seasonal to inter-annual scales, is of great importance in areas where fishing pressure is high. The remoteness of the deep-sea environment constitutes a challenge for monitoring these populations. The few studies that have investigated population structure of deep-sea species, have used trawls, a destructive approach for benthic ecosystems. The development of deep-sea observatories offers a continuous long-term presence on the seafloor. Using imagery from the Ocean Network Canada deep-sea observatory, video footage was acquired on a daily basis and analyzed to describe the population dynamics of the deep-sea crab Chionoecetes tanneri located in depths of 900-1000 m in Barkley Canyon, off Vancouver Island (BC, Canada). The objectives here were to describe the dynamics of the local population in relation to changes in environment and/or life-cycle related behaviors. Sampling sites were located along the canyon axis and on the canyon wall. Only juveniles (1-10 cm) were found at the axis site (1000 m depth) with densities varying from 0 to 144 individuals/m(2). On the canyon wall (900 m depth), adults (> 10 cm) were sporadically observed and densities were lower (max. 13 individuals/m(2)). Variation in density between the two sites reflected the observed arrival of small individuals (