Estimates of maximum population growth rate and steepness for shortfin makos in the North and South Atlantic Ocean

Maximum population growth rates and steepness values of the Beverton-Holt stock recruitment relationship were computed for North and South Atlantic stocks of shortfin mako (Isurus oxyrinchus) based on biological information provided at the 2017 Shortfin Mako Data Preparatory meeting and soon thereafter. I used a dual life table/Leslie matrix approach to obtain estimates of the intrinsic rate of increase (rmax), net reproductive rate (R0), generation time (1), and derived steepness (h) analytically. To encompass a plausible range of biological values, different assumptions on growth, reproduction, and natural mortality were considered. Estimated productivity ranged from rmax=0.031 to 0.060 yr-1 for the North Atlantic stock and from rmax=0.066 to 0.123 yr-1 for the South Atlantic stock and steepness ranged from h=0.34 to 0.52 for the North Atlantic stock and h=0.44 to 0.72 for the South Atlantic stock. These estimates can be used to formulate informative priors of rmax and h in production and agestructured stock assessment models, respectively.