Artificial light improves size selection for northern shrimp (Pandalus borealis) in trawls

Abstract

Size selection in the northern shrimp (Pandalus borealis) trawl fisheries is a widely studied topic. While the focus has largely been on codend and grid selectivity, studies have shown the importance of other design changes and the application of artificial light to evoke behavioural responses. LED lights of three different colours; green (~470–580 nm), white (~425–750 nm) and red (~580–670 nm), were mounted in the belly section of a shrimp trawl to investigate their influence on the overall selectivity of the trawl. The study was conducted using a twin-trawl setup, one with light and the other without light. For catch-comparison analysis, a polynomial regression with random effects was applied. The number of valid hauls with green, white and red lights were eleven, eight, and nine, respectively. All lights tested significantly affected the length-dependent retention of shrimp. Green light had the greatest effect, red the least. Significant loss was observed for shrimp below 17.5 mm carapace length (CL) for green light, 19.5 mm CL for white and 20.8 mm CL for red light.

The effect of artificial lure type and environment conditions on the short‐time post‐release mortality of two recreational fished Luciobarbus species

“…Several studies suggest a substantial influence of colour on catch rates of fish and show that lure colour success can shift with water clarity and colour (Cronin et al, 2014;Ingólfsson et al, 2021;Nieman et al, 2020;Sibeaux et al, 2019). The finding of this study is also in line with the results of the aforementioned studies determining the significant influence of lure colour on catch rates.…”

Simple and effective: T90 codends improve size selectivity and catch efficiency compared with diamond-mesh codends for mantis shrimp (Oratosquilla oratoria) in demersal trawl fishery of the South China Sea

“…There are many simple options, however, that need to be tested and considered. For instance, using the square mesh panels in the diamond-mesh codends (Graham and Kynoch, 2001;Cuende et al, 2020;Kennelly and Broadhurst, 2021), shortening the lastridge ropes (Sistiaga et al, 2021), and adding artificial stimuli (Krag et al, 2017;Grimaldo et al, 2018;Melli et al, 2018;Ingoĺfsson et al, 2021) have been demonstrated to be simple and effective modifications to improve the size selectivity. It is suggested that future investigations should test and evaluate these modifications to further improve the size selectivity and catch efficiency of trawl fisheries for mantis shrimp in the SCS.…”

T90 Codends Improve the Size Selectivity and Catch Efficiency of Shrimp Trawl Fisheries for Southern Velvet Shrimp (Metapenaeopsis palmensis) in the South China Sea

“…This implies that, if the MLS is set to be close to 7.0 cm, more gear modifications should be considered and tested to further improve the size selectivity. A lot of potential modifications, such as using square mesh panel (SMP), shortening lastridge ropes, and applying light-emitting diodes (LED), have been proven to be effective in improving the size selectivity for many species [50][51][52][53][54][55][56][57][58]. Another relevant direction for future work is to estimate the mortality of southern velvet shrimp escaping from the selective codends because the final benefits of improving the size selectivity depends on the survival of escapees [59].…”