Academic article

Physiological and flesh quality consequences of pre-mortem crowding stress in Atlantic mackerel (Scomber scombrus)

Anders, Neil; Eide, Ida; Lerfall, Jørgen; Roth, Bjørn; Breen, Michael

Publication details

Journal: PLOS ONE, vol. 15, p. 25, Thursday 13. February 2020

Issue: 2

International Standard Numbers:
Printed: 1932-6203
Electronic: 1932-6203

Open Access: gold


In commercial wild capture pelagic fisheries it is common practice to crowd catches to high
densities to allow efficient pumping onboard. Crowding during the final stages of purse
seine capture for small pelagic species often results in intense and sustained behavioural
escape responses. Such a response may trigger a shift in energy production from aerobic to
anaerobic pathways and result in metabolic acid accumulation and exhaustion of intracellular
reserves of ATP. Where there is insufficient time or opportunity to recover to physiological
equilibrium before death, pre-mortem stress may be an important determinant of fillet
quality, as has been shown for a variety of farmed fish species. However, there is currently a
lack of knowledge related to the flesh quality implications of capture stress for wild captured
species in European waters. Here we show that crowding results in a physiological stress
response that has consequences for flesh quality in the wild captured species Atlantic mackerel
(Scomber scombrus). Using small schools in tanks and aquaculture net pens in three
separate experiments, we found crowding results in physiological changes in mackerel consistent
with an acute stress response and anaerobic metabolism. Consequently, we found
crowded fish had more acidic pre- and post-mortem muscle pH as well as indications of
faster onset and strength of rigor mortis and increased cathepsin B & L activity. We examined
fillet flesh quality after two and seven days of ice storage and found reduced green colouration,
increased gaping (separation of muscle myotomes) and reduced textural firmness
associated with fish which had been crowded. However, the effects on quality were dependant
on experiment and/or storage time. These results indicate the potential of crowding
capture stress to influence the flesh quality of an economically important species and may
have important implications for the wild capture pelagic fishing industry.