where thousand tonnes is the threshold stock, equal to the minimum estimated SSB in the Western mackerel SSB time series (1972 - 96) scaled by the ratio of the mean of the North-East Atlantic SSB to the that of the Western component (1984 - 96); and million fish is the geometric mean (1972-1996) of recruitment to the Western mackerel, raised by the ratio (1.156) of the estimated Western and North-East Atlantic mackerel recruitments for the period 1984-1996 (ICES 2000, pp. 45-46).
thousand 
million fish is the geometric mean (1972-1996) of recruitment