Background: In Mexico Haliotis fulgens catch decreased considerably in 2012. In other countries like U.S.A., Australia, and Tasmania, their decline was associated with death by pathogens. Goals. We studied the bacterial effect on the concentration of some biochemical components of haemolymph of H. fulgens.

Methods: Eight apparently sick abalone of culture and five healthy abalone were collected in 2013. The concentration of glucose, total proteins, albumin, globulins, and bacterial species were obtained.

Results: We found Vibrio alginolyticus, Acinetobacter lwoffii, Serratia sp. y Aeromonas hydrophila. The diseased abalone had a higher total protein concentration than the healthy abalone (1.20 g/dl and 1.09 g/dl, p < 0.05, respectively). The increase of glucose, total proteins, globulins, and albumins was directly proportional with bacterial effect.

Conclusion: This is the first report of V. alginolyticus, A. lwoffii, Serratia sp. y A. hydrophila in H. fulgens, cultivated in La Boca, Baja California Sur, Mexico. A regression analysis showed a negative effect on the biochemical components of hemolymph due to these bacteria.