Abstract
Since 2000, the Shetland inshore scallop fishery has been managed by the Shetland Shellfish Management Organisation (SSMO) enabled by a fishery regulating order (currently the Shetland Islands Regulated Fishery (Scotland) Order 2012). The fishery has grown significantly, with landings increasing from 700,000 scallops in 2000 to over 5.1 million in 2023. The fishery is accredited by the Marine Stewardship Council (MSC) and a 2012 MSC report recommended the analysis of scallop fishery bycatch species.
This report investigates differences in bycatch species composition between two bycatch surveys conducted during 2012/13 and 2017/18 within the 6nm limit around the Shetland Islands.
Bycatch data were collected through commercial vessel surveys and using UHI Shetland’s fishery research survey vessel (2012/13 and 2017/18), representing 194 tows. To assess the dis/similarities in bycatch species composition these tows have been analysed in the statistical package PRIMER using non-metric multidimensional scaling (nMDS). Analysis of Similarity (ANOSIM) and SIMPER were used to evaluate differences in species composition among survey types, vessels, and years.
The spatial spread of surveys was found to differ geographically between survey type (commercial v UHI Shetland fisheries research vessel), but not across survey years, except for a minor expansion in survey area in 2017/18 into previously unsurveyed regions in south Shetland. Commercial tows were concentrated around specific fishing areas due to operational habits of individual vessels, offering clear insights into direct bycatch species composition but not covering all areas used by the fishery. UHI Shetland research vessel surveys spanned a wider geographical area, providing a more comprehensive overview of bycatch species across various habitats within the scallop fishery grounds.
The species-accumulation curve indicated that total bycatch species diversity was not fully captured within single-year surveys, suggesting that cumulative multi-year sampling is necessary for an accurate assessment. The nMDS and ANOSIM analyses showed no significant influence of survey type or vessel on bycatch species composition. However, significant differences were found between 2012/13 and 2017/18 surveys (ANOSIM, P = 0.1%). These differences were driven by variations in the abundance of the top five species; Echinus esculentus (edible sea urchin), Luidia ciliaris (seven-armed sea star), Astropecten irregularis (sand sea star), Neptunea antiqua (red whelk) and Asterias rubens (common sea star), which significantly impacted overall bycatch composition. Fishing practices and spatial coverage likely contributed to observed fluctuations.
This report investigates differences in bycatch species composition between two bycatch surveys conducted during 2012/13 and 2017/18 within the 6nm limit around the Shetland Islands.
Bycatch data were collected through commercial vessel surveys and using UHI Shetland’s fishery research survey vessel (2012/13 and 2017/18), representing 194 tows. To assess the dis/similarities in bycatch species composition these tows have been analysed in the statistical package PRIMER using non-metric multidimensional scaling (nMDS). Analysis of Similarity (ANOSIM) and SIMPER were used to evaluate differences in species composition among survey types, vessels, and years.
The spatial spread of surveys was found to differ geographically between survey type (commercial v UHI Shetland fisheries research vessel), but not across survey years, except for a minor expansion in survey area in 2017/18 into previously unsurveyed regions in south Shetland. Commercial tows were concentrated around specific fishing areas due to operational habits of individual vessels, offering clear insights into direct bycatch species composition but not covering all areas used by the fishery. UHI Shetland research vessel surveys spanned a wider geographical area, providing a more comprehensive overview of bycatch species across various habitats within the scallop fishery grounds.
The species-accumulation curve indicated that total bycatch species diversity was not fully captured within single-year surveys, suggesting that cumulative multi-year sampling is necessary for an accurate assessment. The nMDS and ANOSIM analyses showed no significant influence of survey type or vessel on bycatch species composition. However, significant differences were found between 2012/13 and 2017/18 surveys (ANOSIM, P = 0.1%). These differences were driven by variations in the abundance of the top five species; Echinus esculentus (edible sea urchin), Luidia ciliaris (seven-armed sea star), Astropecten irregularis (sand sea star), Neptunea antiqua (red whelk) and Asterias rubens (common sea star), which significantly impacted overall bycatch composition. Fishing practices and spatial coverage likely contributed to observed fluctuations.
| Original language | English |
|---|---|
| Publisher | UHI Shetland |
| Number of pages | 22 |
| DOIs | |
| Publication status | Published - 30 Jan 2024 |