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Selenium and mercury were evaluated in muscle, liver, kidney, brain, and the stomach contents of juvenile scalloped hammerhead shark Sphyrna lewini. Se:Hg molar ratios were calculated. The average Hg levels in muscle ranged from 0.12 to 1.17 μg/g (wet weight); Hg was <0.39 μg/g in liver and kidneys and <0.19 μg/g in brain. The lowest value of Se was found in muscle (0.4 μg/g) and the highest in kidney (26.7 μg/g). An excess of Se over Hg was found, with Se:Hg molar ratios >1. Correlations were found for Hg in muscle with size, age, and weight, and also for Hg in liver with size, age, and weight. Hg in muscle was significantly positive correlated to Hg in brain as well as Hg in liver was correlated to Hg in kidney. The highest Hg in preys was for carangid fishes; scombrid and carangid fishes contributed with the highest Se levels. Results suggest that more than 98 % of the total Hg and 62 % of Se end up in muscle and might be affected by factors, such as geographical area, age, size, and feeding habits. The muscle of S. lewini should be consumed by people cautiously so as not to exceed the recommended intake per week.

RESUMEN.La Isla Isabel es un Parque Nacional localizado en el noroeste de México, cuya área marina no está protegida y la pesca artesanal está permitida, aunque los impactos de esta actividad sobre el ecosistema y los recursos naturales explotados no han sido evaluados. De mayo 2013 a abril 2014 se monitoreó mensualmente diferentes campos pesqueros de la Isla Isabel. Los artes de pesca más utilizados fueron la red de enmalle (96,4%), la línea de mano (2,1%) y la cimbra (1,5%), capturándose 2.388 ejemplares pertenecientes a 19 familias, 33 géneros y 46 especies. Las especies mejor representadas en las capturas fueron Lutjanus peru (%IIR = 55,34), L. guttatus (%IIR = 16,01), L. argentiventris (%IIR = 11,53), Cynoscion reticulatus (%IIR = 3,23) y Hoplopagrus guentherii (%IIR = 3,02), representando 89,13% de la captura total. La diversidad fue baja (H' = 2,01), dominada por pocas especies (J' = 0,52), principalmente pargos (Lutjanidae). Palabras clave: Lutjanidae, pesca artesanal, Parque Nacional, Isla Isabel, Golfo de California. Ichthyofauna catch composition in a small-scale fishery from Isabel Island (southeastern Gulf of California), MexicoABSTRACT. Isabel Island is a National Park located in the northwest Mexico with an unprotected marine area, where the small-scale fishing is allowed. The impact of this activity in the ecosystem and exploited biological resources has not been evaluated. From May 2013 to April 2014 the fishing grounds of Isabel Island were monthly monitored. The most widely used fishing gears were the gillnet (96.4%), hook-and-line (2.1%) and long-line (1.5%). A total 2,388 specimens were caught, corresponding to 19 families, 33 genera, and 46 species. The most frequent species caught were Lutjanus peru (%IRI = 55.34), L. guttatus (%IRI = 16.01), L. argentiventris (%IRI = 11.53), Cynoscion reticulatus (%IRI = 3.23) and Hoplopagrus guentherii (%IRI = 3.02), representing 89.13% of the total catch. The diversity was low (H' = 2.01), dominated by few species (J' = 0.52), mainly snappers (Lutjanidae).

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Madigan et al. (2021) recently reported a supposedly illegal fishery targeting white sharks in the Gulf of California (GC), Mexico. While we are strongly against illegal fishing and recognize the need to enhance enforcement to pro-This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.