Novel Use of PIT Tags in Sea Cucumbers: Promising Results with the Commercial Species Cucumaria frondosa

PLOS ONE, Dec 2019

The lack of a reliable and innocuous mark-recapture method has limited studies that would provide essential information for the management of commercial sea cucumbers. Tagging sea cucumbers is notoriously difficult because of their plastic nature and autolysis capacities. The markers that have so far been tested, mainly on or through the body wall, were either lost rapidly or had major drawbacks (e.g. suitable only for batch identification, requiring complex analysis, causing infections, necrosis, behavioural changes and mortality). The present study explored the efficacy of passive integrated transponder (PIT) tags for individually marking sea cucumbers by assessing retention rates and long-term side effects of tags inserted in previously unstudied tissues/organs. Individuals of the species Cucumaria frondosa were tagged in the body wall, aquapharyngeal bulb and at the base of the oral tentacles. They were monitored closely for evidence of stress, infection, change in feeding and spawning behaviour and tag retention rate. Implanting the tag in an oral tentacle to reach the hydrovascular system of the aquapharyngeal bulb achieved the best retention rates in full-size individuals: from a maximum of 92% after 30 days to 68% at the end of the experimental period (300 days). Efficacy was lower in smaller individuals (84% after 30 d and 42% after 300 d). Following a slight increase in cloacal movements for 15 h post tagging, no side effect was noted in sea cucumbers tagged in the aquapharyngeal bulb via the tentacles. Feeding and spawning behaviours were not affected and no signs of infections or abnormal cell development in the vicinity of the tags were observed. This study indicates that marking sea cucumbers with 8.2 mm long PIT tags implanted via the oral tentacle is an effective technique, yielding relatively high retention rates over long periods without any detectable physiological or behavioural effects.

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Novel Use of PIT Tags in Sea Cucumbers: Promising Results with the Commercial Species Cucumaria frondosa

May Novel Use of PIT Tags in Sea Cucumbers: Promising Results with the Commercial Species Cucumaria frondosa Bruno L. Gianasi 0 1 2 Katie Verkaik 0 1 2 Jean-Franois Hamel 0 1 2 Annie Mercier 0 1 2 0 1 Department of Ocean Sciences (OSC), Memorial University , St John's, Newfoundland and Labrador , Canada , 2 Society for the Exploration & Valuing of the Environment (SEVE) , St Philips, Newfoundland and Labrador , Canada 1 Funding: This study was funded by Research & Development Corporation of Newfoundland & Labrador (RDC), Department of Fisheries and Aquaculture of Newfoundland & Labrador (DFA) and Canadian Centre for Fisheries Innovation (CCFI). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript 2 Academic Editor: Peter S. Petraitis, University of Pennsylvania, UNITED STATES The lack of a reliable and innocuous mark-recapture method has limited studies that would provide essential information for the management of commercial sea cucumbers. Tagging sea cucumbers is notoriously difficult because of their plastic nature and autolysis capacities. The markers that have so far been tested, mainly on or through the body wall, were either lost rapidly or had major drawbacks (e.g. suitable only for batch identification, requiring complex analysis, causing infections, necrosis, behavioural changes and mortality). The present study explored the efficacy of passive integrated transponder (PIT) tags for individually marking sea cucumbers by assessing retention rates and long-term side effects of tags inserted in previously unstudied tissues/organs. Individuals of the species Cucumaria frondosa were tagged in the body wall, aquapharyngeal bulb and at the base of the oral tentacles. They were monitored closely for evidence of stress, infection, change in feeding and spawning behaviour and tag retention rate. Implanting the tag in an oral tentacle to reach the hydrovascular system of the aquapharyngeal bulb achieved the best retention rates in full-size individuals: from a maximum of 92% after 30 days to 68% at the end of the experimental period (300 days). Efficacy was lower in smaller individuals (84% after 30 d and 42% after 300 d). Following a slight increase in cloacal movements for 15 h post tagging, no side effect was noted in sea cucumbers tagged in the aquapharyngeal bulb via the tentacles. Feeding and spawning behaviours were not affected and no signs of infections or abnormal cell development in the vicinity of the tags were observed. This study indicates that marking sea cucumbers with 8.2 mm long PIT tags implanted via the oral tentacle is an effective technique, yielding relatively high retention rates over long periods without any detectable physiological or behavioural effects. - Competing Interests: The authors have declared that no competing interests exist. The high demand and high market prices for beche-de-mer (dry body wall) spurred by cultural and social traditions in China have led to the growth of sea cucumber fisheries and, consequently, to the depletion of wild stocks of high-value species all over the world [16]. Cucumaria frondosa is the focus of an emerging fishery in the Northwest Atlantic, and it has already become one of the predominant commercial sea cucumber species in terms of landed weight [7]. Although growth rates in C. frondosa are very low in the wild and in captivity [8,9], the species is considered to have potential for aquaculture in the North Atlantic due to its high marketability for food and pharmaceutical products and because much of its life cycle is well documented [79]. It is currently being explored as an extractive species for integrated multi-trophic aquaculture [10]. Several studies have been conducted on sea cucumber ecology in the context of conservation and management efforts [1,8,9,1115]. However, the lack of an easy and reliable technique to mark individuals has hindered tracking and capture-recapture studies, which provide key biological information (e.g. movement and migration patterns, growth, estimates of natural mortality). The development of an effective tagging technique that minimizes tissue damage, stress and infections, while maximising retention rates will be of great value in years to come, as this fishery expands and aquaculture develops. Such a tool will benefit the sea cucumber industry worldwide by allowing fishery-oriented and ecological studies using mark-recapture to examine temporal changes in growth, survival and mortality rates, as well as daily and seasonal migrations, localization of breeding populations and determination of habitat preferences in the field [16,17]. The difficulties in tagging sea cucumbers are attributed to the plasticity of the body wall, lack of hard tissue, high likelihood of expelling foreign materials and the common occurrence of infections and necrosis around the tagged area [17,18]. Most of the techniques tested so far (summarized in Tab (...truncated)


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Bruno L. Gianasi, Katie Verkaik, Jean-François Hamel, Annie Mercier. Novel Use of PIT Tags in Sea Cucumbers: Promising Results with the Commercial Species Cucumaria frondosa, PLOS ONE, 2015, 5, DOI: 10.1371/journal.pone.0127884