Total mercury concentrations in white and striped Mullet (Mugil curema and M. cephalus) from a coastal lagoon in the SE Gulf of California.

The White and Striped mullets (Mugil curema and M. cephalus) are highly abundant and commercially important estuarine fish in northwest (NW) Mexico. Because of their feeding habits and habitat, they are likely to accumulate mercury (Hg) in their muscle and liver. The objectives of this study were to determine total Hg distribution in the tissues of interest, to correlate Hg levels between tissues and with length and weight of fish, to estimate the percentage weekly intake (PWI) of total Hg and methyl Hg (MeHg) through consumption of both mullet species, and to compare total Hg levels with mullets from other areas. The highest total Hg concentration (1.031 µg g-1 dry weight) was measured in liver of White mullet. In both species, the order of averaged Hg concentrations (M. curema liver 0.272, muscle 0.184; M. cephalus liver 0.211, muscle 0.129 µg g-1 dry weight) were liver>muscle. Correlations of Hg in muscle and liver with total weight of M. curema were significant. In M. cephalus, Hg levels in liver were significantly correlated with total length and weight. The PWI of THg (<4%) and MeHg (<10%) were not elevated for both species. Concentration of Hg in the studied mullets was comparable to levels in similar species from Mexican waters but lower than results in mugilids from other coastal areas.

Mercury levels in selected bycatch fish species from industrial shrimp-trawl fishery in the SE Gulf of California.

Baseline Hg concentration in bycatch fish from the SE Gulf of California were determined in muscle and liver of 19 species. Levels of Hg in muscle were compared with legal limits of this element in national and international legislation. Considering all fish species, mean concentrations in liver (2.458±1.997 µg g⁻¹) were significantly higher (p<0.05) than in muscle (0.993±0.670 µg g⁻¹). The sequence of averaged Hg concentrations in most ichthyofauna was liver>muscle. Highest level of Hg in muscle (2.556 µg g⁻¹) and liver (7.515 µg g⁻¹) corresponded to Diapterus peruvianus and Ophioscion strabo, respectively. Considering muscle samples, none of the species had levels of Hg above the limit (1.0 µg g⁻¹ wet weight) in the Mexican legislation; with respect to the Japanese (0.4 µg g⁻¹ wet weight) and British (0.3 µg g⁻¹ wet weight) legislations, 26.3% and 31.6% of the species respectively, were above the corresponding limits.