Demersal shrimp trawling is among the least selective fishing methods, posing a considerable threat to marine ecosystems due to the catch of nontarget species (bycatch). Even when bycatch is immediately released, physical damage to organisms may reduce their survival. The probability of long-term survival and oxidative stress markers of two species of Sciaenidae fish, Paralonchurus brasiliensis and Stellifer rastrifer, caught incidentally while trawling for shrimp in the State of Paraná—Brazil, were analyzed. The mortality rate for both species was found to be high (P. brasiliensis, 76.94%, n = 337 and S. rastrifer, 69.32%, n = 2.586). Among other factors, mortality was associated with body size and the physical damage suffered. Smaller fish showed a higher incidence of damage, most commonly scale-loss and contusions or haematomas on the head and body. The mortality rate and catch damage index (CDI) were similar for both species, but were aggravated by higher tow durations (15, 30, and 45 min). The CDI can be a good predictor of mortality. The probability of survival improved in winter for both species. Increased lipid peroxidation and protein carbonylation were identified in P. brasiliensis but not in S. rastrifer. This indicates that the two species responded in different ways to the stressful conditions produced by trawling. Considering the oxidative stress markers identified, it appears that the high mortality rate recorded in two species was more closely associated with physical damage than oxidative stress markers.

底层虾拖网是选择性最少的捕捞方法之一，由于捕获非目标物种（兼捕），对海洋生态系统构成了相当大的威胁。即使立即释放兼捕，对生物体的物理损害也可能会降低它们的存活率。分析了巴西巴拉那州在拖网捕虾时偶然捕获的两种 Sciaenidae 鱼类Paralonchurus brasiliensis和Stellifer rastrifer的长期存活概率和氧化应激标记。发现这两种物种的死亡率都很高（P. brasiliensis , 76.94%, n = 337 and S. rastrifer, 69.32%, n = 2.586)。除其他因素外，死亡率与体型和遭受的身体伤害有关。较小的鱼表现出更高的损伤发生率，最常见的是头部和身体上的鳞片脱落和挫伤或血肿。两种物种的死亡率和捕获损伤指数 (CDI) 相似，但拖曳时间较长（15、30 和 45 分钟）会加剧这种情况。CDI 可以很好地预测死亡率。这两个物种在冬季的生存概率都有所提高。在P. brasiliensis中发现脂质过氧化和蛋白质羰基化增加，但在S. rastrifer 中未发现. 这表明这两个物种以不同的方式应对拖网捕捞产生的压力条件。考虑到已鉴定的氧化应激标记，与氧化应激标记相比，两个物种的高死亡率似乎与物理损伤的关系更密切。