Targeting high quality adult habitat important for rockfish protection & MPA design



Two recent studies published in MEPS give new insight into rockfish population dynamics in Barkley Sound with 7 years of survey data. First, Markel et al (2017) analyzed the environmental drivers of recruitment for young-of-the-year Pacific rockfishes Sebastes spp. in kelp forest and eelgrass meadow habitats. They found that environment and geography can interact with characteristics of habitat, including habitat size, to influence observed recruitment, thus habitat characteristics can play a multitude of roles in mediating or exacerbating post-settlement processes. Black rockfish recruitment to both kelp forest and eelgrass sites could be explained in some years by environmental factors such as tidal velocity and sea surface temperatures, and geographic factors such as distance to the open coast and fetch. Recruitment to both kelp forest and eelgrass sites in other species of rockfish (copper, quillback and brown rockfish) could be consistently explained by tidal velocity and fetch. While it is likely that these environmental variables are indicators of larval supply to the study sites, they may also reflect physiological preferences or post-settlement mortality of recent settlers. 
Dr. Russell Markel*, Dr. Katie Lotterhos* & Dr. Clifford Robinson

In a follow-up study, Haggarty et al. (2017) tested whether strong year classes of age 0 recruits made up a disproportionate portion of the adult population. They found that variation in adult abundance was not explained by age 0 year class abundance, but that a portion of the variation was explained by the abundance of 1-year old fish. However, most of the variance in adult abundance was explained by habitat metrics such as rocky substrate and habitat complexity.  Their results point to overwinter mortality in the first year as a potentially important bottleneck for rockfish populations, and that habitat quality is an important metric for the design of reserves. K.E. Lotterhos

Young-of-the-year recruitment does not predict the abundance of older age classes in black rockfish in Barkley Sound, British Columbia, Canada MEPS, Vol. 574: 113–126, 2017

Dr. Dana Haggarty*, Dr. Katie Lotterhos*, & Dr. Jon Shurin*

*BMSC Alumni

Eelgrass and kelp forest sampling locations throughout Barkley Sound.