Remarkable variability in stress responses among subtropical coastal marine teleosts

The relevance of the plasma cortisol response as primary stress marker in teleost fishes is well known. However, available data still refer to a low number of species, considering the huge diversity of teleosts. To improve the data base of the cortisol response in feral coastal marine teleosts, this study aimed at evaluating the response-survival and plasma cortisol, glucose, osmolality, chloride, and magnesium-of marine teleosts to the capture stress of trawling. Fish sampled were divided into three groups: dead after trawling, alive after trawling, and live fish which were kept for similar to 12 h in a tank after trawling ("overnight in tank"). Blood samples (224) of 36 species from 19 fish families have been assessed. A large variability in the cortisol response among species, within the three groups, was detected. The Brazilian silverside Atherinella brasiliensis was notable in showing essentially only very high values (> 1000 ng/mL). Some species always showed very low levels (nearly zero, e.g., most Scianidae species). Most species displayed a very broad range of values (10-1000 ng/mL), such as Eucinostomus argenteus. Inter-specific variability was also present in plasma glucose, osmolality, and ions. The response to trawling stress in wild coastal marine teleost fish species is thus extremely variable. Better knowledge about the diversity in the response of teleosts to stress contributes to fisheries management, aiming at sustainability.