Predicting the Size Selectivity Based on the Striped Red Mullet Morphology (Mullus surmuletus) in Bottom Trawl Fisheries

Year 2018, Volume: 33 Issue: 3, 90 - 95, 28.06.2018

Enis Noyan Kostak Adnan Tokaç

Abstract

DOI: 10.26650/ASE201817

The striped red mullet (Mullus surmuletus)
is a commercially important demersal species caught by mixed trawl fishing in
the Mediterranean Sea. Although it is not among the target species of bottom
trawl operations, the striped red mullet is an important species due to its
high commercial value in trawl catch composition. The primary target is to
catch adult individuals while allowing the immature and juvenile fish to escape
for sustainable fisheries using selective fishing gears. Various selectivity
studies regarding trawl codends aimed at improving selectivity have been
carried out in the past two decades. However, the selectivity sea trials
generally require a great deal of work, time, and labor on the deck and are
also expensive. Therefore, instead of experimental-based selectivity studies,
simulation-based studies (i.e., the FISHSELECT methodology) were recently
started to predict the size selectivity of species in bottom trawl fisheries.
In this study, sampled individuals of the striped red mullet were used in
morphological measurements, fall-through experiments, and simulation phases.
Diamond mesh sizes of 40, 44, and 50 mm and a square mesh size of 40 mm of
bottom trawl codends were simulated, and the L50 values were calculated as
9.87, 10.75, 12.19, and 12.3 cm for the aforementioned mesh sizes,
respectively. Design guides were then created for various mesh sizes and
opening angles. The study results were compared with those of previous studies
on the red mullet (M. barbatus) that were conducted using the FISHSELECT
methodology, and the selectivity results of these two species were found to be
similar.

Keywords

FISHSELECT, striped red mullet, Mullus surmuletus, selectivity, bottom trawl

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