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Balancing fishery and conservation: a case study of the barrel jellyfishRhizostoma octopusin South Wales / Anna Elliott, Victoria Hobson, Kam Tang

ICES Journal of Marine Science: Journal du Conseil, Volume: 74, Pages: 234 - 241

Swansea University Author: Kam Tang

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DOI (Published version): 10.1093/icesjms/fsw157

Abstract

In Wales, the barrel jellyfish Rhizostoma octopus is commercially harvested to produce high-value medical grade collagen. While the fishery is presently not regulated, there are concerns how it may affect the leatherback turtle (Dermochelys coriacea), which preys on R. octopus in local waters. We co...

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Published in: ICES Journal of Marine Science: Journal du Conseil
ISSN: 1054-3139 1095-9289
Published: 2017
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URI: https://cronfa.swan.ac.uk/Record/cronfa29636
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Abstract: In Wales, the barrel jellyfish Rhizostoma octopus is commercially harvested to produce high-value medical grade collagen. While the fishery is presently not regulated, there are concerns how it may affect the leatherback turtle (Dermochelys coriacea), which preys on R. octopus in local waters. We combined monitoring data and morphometric and weight measurements in models to estimate the potential impact of R. octopus fishery on foraging turtles. We found a significant quadratic relationship between bell diameter and wet weight of R. octopus, with bell diameter explaining 88% of the variability in wet weight. R. octopus biomass in the Carmarthen Bay varied inter-annually between 38.9 and 594.2 tonnes y-1. The amount of R. octopus needed to satisfy a leatherback turtle’s daily energetic requirements was estimated at 85.1-319.1 kg. Using leatherback turtle sighting data, our models show that during a jellyfish ‘low year,’ the R. octopus population could be completely depleted by an average of two foraging turtles along with the current level of commercial harvesting (4.3 tonnes). During a jellyfish ‘high year,’ the current level of commercial harvesting is predicted to have relatively little impact on food supply for even the maximum number of foraging leatherback turtle reported in the area. However, uncertainties related to the jellyfish’s life cycle in the local waters need to be resolved for proper management of this emerging fishery.
Item Description: The giant barrel jellyfish R. octopus is occurring in increasing frequency along the coast of South Wales, UK. This observation has prompted a new fishery harvesting the jellyfish to produce high-value medical grade collagen. This new fishery is presently not regulated, but there is concern how it may affect the leatherback turtle that forages in the region. We used morphometric and weight measurements of the barrel jellyfish, and sighting data of the leatherback turtle, in models to investigate the potential impact of a jellyfish fishery on the leatherback turtle. The novel findings provide the basis for managing this new fishery in a manner that is sustainable and compatible with the leatherback turtle conservation effort.
Keywords: Barrel jellyfish; Conservation; Leatherback turtle; Rhizostomeae; Rhizostoma octopus; Fishery
College: College of Science
Start Page: 234
End Page: 241