Worldwide, many sharks and rays (also called elasmobranchs) are overfished. These fisheries impacts are made worse because sharks also are caught as bycatch - some of these bycaught sharks are then discarded back into the ocean, while others are sold in markets. But records on bycatch and discards of sharks are notoriously poor. At issue is how to measure the total effect of fisheries which must account for the magnitude and extent of shark and ray retention (for market) as well as discards. Recent research in the Lewison Lab (collaborating with NOAA SWFSC and UNE) is working to take a bite of this challenging problem. Kelsey James (Univ of Rhode Island) led efforts to construct and analyze a large database of shark literature which reported catch and bycatch statistics from 30 countries, 306 elasmobranch species, totalling over 2000 records. This research is currently featured in Environmental Conservation
The goal of the research was to look for patterns in species retention and discards that could help managers navigate the complexity of estimating fisheries impacts on elasmobranchs. While variability in percent retained was high, we found that species type, fishing country, and gear explained nearly 60% of the variance. This suggests that while elasmobranch impacts in fisheries are challenging to track, even without data, we can make some inferences about the magnitude of total elasmobranch capture. When we compared our estimates to global landings data of elasmobranchs from the Food and Agricultural Organization of the United Nations (FAO), we found that FAO landings may grossly underestimate total elasmobranch removals by as much as 400%.
Our work brings attention to the need to improve estimates of elasmobranch removal - to account for all retained catch and discards - and highlights the importance of continued efforts to monitor and report retention and discards of elasmobranchs.
The goal of the research was to look for patterns in species retention and discards that could help managers navigate the complexity of estimating fisheries impacts on elasmobranchs. While variability in percent retained was high, we found that species type, fishing country, and gear explained nearly 60% of the variance. This suggests that while elasmobranch impacts in fisheries are challenging to track, even without data, we can make some inferences about the magnitude of total elasmobranch capture. When we compared our estimates to global landings data of elasmobranchs from the Food and Agricultural Organization of the United Nations (FAO), we found that FAO landings may grossly underestimate total elasmobranch removals by as much as 400%.
Our work brings attention to the need to improve estimates of elasmobranch removal - to account for all retained catch and discards - and highlights the importance of continued efforts to monitor and report retention and discards of elasmobranchs.
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