Discards survival probabilities of flatfish and rays in North Sea pulse-trawl fisheries

Abstract

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Increasing the survival of discards in North Sea pulse-trawl fisheries

“…(95%CI 11-18%) for plaice (Schram and Molenaar, 2018). For undersized sole we reported a slightly lower discards survival than Van der Reijden et al (2017) of 19% (95%CI 13-28%).…”

“…We previously established that survival probability increases with improving condition of the discarded fish (Schram and Molenaar, 2018). To investigate mechanisms that underlie the effect of a water filled hopper, we looked into the effect of this measure on the condition of discarded fish.…”

Direct mortality among demersal fish and benthic organisms in the wake of pulse trawling

“…The direct survival observed in the current study is comparable to the direct survival of plaice and sole sampled from two hour tows by commercial pulse trawlers in our discards survival studies (Schram and Molenaar, 2018). However, in that study delayed mortality, mainly occurring during the first five days post capture, ultimately resulted delayed discards survival that was much lower than the direct survival.…”

Best practices II : Effect on future development of sole and plaice of changing mesh size from 80mm to 90mm in the beam trawl fishery

“…For both stocks, simulations were run for 3 scenarios on the survival rate: the lower and upper limits of the confidence bounds of the available estimates of survival rate, and a 0% survival. The limits of the confidence bounds for sole and for plaice are 13% and 28%, and 11% and 18% respectively (Schram and Molenaar, 2018). These percentages were rounded to 10% and 30%, and 10% and 20% so that the stock assessments, developed with these percentages by Verkempynck et al (2018) can be used as a basis for these simulations, without having to set up new assessments.…”