Age, growth and mortality of Caulolatilus princeps (Pisces: Malacanthidae) from the southern Gulf of California

Abstract

The morphometric relationships, age, and growth of the Ocean Whitefish (Caulolatilus princeps, Jenyns 1842) were studied from a sample of 1783 specimens (1196 individuals for ageing), taken around the Bay of La Paz, in the southern Gulf of California from February 1986 to May 1987. The standard length ranged from 152 to 505 mm, and the eviscerated weight from 150 to 2660 g. The standard length-eviscerated weight relationships were estimated as: W = 0.00029 x L2.922, W = 0.00024 x L2.960, W = 0.00021 x L2.979 for males, females and the sexes combined, respectively. Twenty one age classes, ranging from 1 to 21 years were defined by whole burned otolith readings. Mean standard length, and standard length by otoliths edge-at-age data for the first 16 age groups were used to estimate the growth parameters of the von Bertalanffy equation: L? = 476.7 mm, K = 0.093, to = -3.904, for males; L? = 474.8 mm, K = 0.101, to = -3.339, for females; L? = 460.9 mm, K = 0.113, to = -2.765, for the sexes combined. The asymptotic weights were: 1847.6, 2006.8 and 1972.1 g, for males, females, and the sexes combined, respectively. Total (Z year-1) and natural (M year-1) mortalities were estimated as, respectively: 0.45 and 0.15 for males, 0.42 and 0.15 for females, and 0.41 and 0.17 year-1 for the sexes combined. The exploitation ratios (E) were: 0.67 for males, 0.63 for females, and 0.60 for the sexes combined, indicating that the fishing pressure on this population is higher than the recommended ratio of 0.5.