Evidences of possible influences of methylmercury concentrations on condition factor and maturation of Lophius vomerinus (Cape monkfish).

Muscle and liver tissues of Lophius vomerinus off the coast of Namibia were analysed to investigated the influence of MeHg on the biological parameters of L.vomerinus by (i) determining if the variability in total MeHg concentrations is influenced by length, maturity status and sex, and (ii) assessing if there is a relationship between biological indices (Condition factor (K), Gonadosomatic Index (GSI) Hepatosomatic Index (HSI)) and MeHg concentrations. Correlations between total MeHg concentrations and fish length, K and HSI were observed. A weak positive correlation was observed between total MeHg and GSI for combined sex. Total MeHg concentration in tissues of L. vomerinus is significantly dependent on the maturity stages (p < 0.05). K was significantly inversely correlated with total MeHg in tissues of L. vomerinus. The evidence presented in this study suggests that MeHg in L. vomerinus tissues could be detrimental to both its physiology and population dynamics.

Mercury concentrations in muscles and liver tissues of Cape monkfish (Lophius vomerinus) from the Northern Benguela, Namibia.

Cape monkfish (Lophius vomerinus) is one of the long-lived species and top predators in the northern Benguela region. Studies on bioaccumulation of mercury (Hg) in cape monkfish are limited. This study compared the total Hg concentration between monkfish muscle and liver tissue; and related the monkfish total Hg concentrations to fish body size and capture locations (depth and latitude). Monkfish specimens (n = 529) were collected from 2016 to 2018. The mean total Hg concentration was 0.126 ±â€¯0.005 mg/kg in muscle tissues and 0.106 ±â€¯0.005 mg/kg in liver tissues. No significant differences were observed between total Hg concentrations of muscles and liver tissues. Differences in Hg concentrations between monkfish length classes were observed. No significant correlation was found between total Hg concentrations and latitude. A significant increase of total Hg concentration with the depth was observed. The concentrations of Hg were below the World Health Organization (WHO limits for fish (0.5 mg/kg).