FishSec says “This is particularly serious in the Baltic Sea where eutrophication and a lack of oxygen are key reasons behind the collapse of the cod stocks.
“Bottom trawling can thereby reinforce a vicious circle of decline for cod. The more demersal stocks such as cod, plaice and flounder are trawled – the possibility for the stock to recover and have a healthy environment with plenty of oxygen to help it spawn etc is diminished.”
The study was conducted within a trawl‐exclusion zone of the subtropical Moreton Bay, Australia, which allowed the experimental testing of trawl effects on previously untrawled sediments.
On the chronic effects of trawling the study says “No statistically significant chronic effect of trawling was detected for any measured parameter at any site or time.”
The study goes on to look at many aspects of the effects of bottom trawling but in conclusion it says “There is clearly a high uncertainty associated with scaling a single study, at a single site, to the whole earth, but it is still a useful exercise to highlight the potential for trawling to affect the global nitrogen cycle.”
To read more on the study, click here