Fig. 6. Mass-specific (A) blood oxygen stores, (B) muscle oxygen stores and (C) total oxygen stores as a function of body size was significant for male and female California sea lions. The relationship between body size and mass-specific blood oxygen stores was significant for females (y=0.094x+12.66; r²=0.20, P=0.002) and males (y=0.03x+14.29; r²=0.99, P=0.001), and significant for muscle oxygen stores in females (y=0.14x+9.13; r²=0.78, P<0.001) and males (y=0.02x+12.06; r²=0.37, P<0.001), and total oxygen stores for females (y=0.23x+30.04; r²=0.50, P<0.001) and males (y=0.07x+35.60; r²=0.30, P<0.001). However, the rate of development in mass-specific muscle oxygen stores was greater in females than males, although no greater in blood and total oxygen stores.