Event Abstract

Back to Event

Polychaete annelids as live bait in Portugal: harvesting activity in estuarine systems

Sara Cabral1*, Ana S. Alves1, Nuno Castro1, Pedro Fidalgo E Costa2, Erica Sá1, João Castro3, Luís Cancela Da Fonseca2, 4, Paula Chainho1, João Canning-Clode5, David Picard6, Ana Pombo7 and José Lino Costa1
  • 1 MARE/ULisboa - Marine and Environmental Sciences Centre, Portugal
  • 2 MARE/LMG – Marine and Environmental Sciences Centre, Portugal
  • 3 MARE/UÉvora - Marine and Environmental Sciences Centre, Portugal
  • 4 CTA - Centro de Ciências e Tecnologias da Água, Portugal
  • 5 MARE/Madeira– Marine and Environmental Sciences Centre, Portugal
  • 6 IGD - Institute of Geography and Sustainability, Switzerland
  • 7 MARE/IPLeiria – Marine and Environmental Sciences Centre, Portugal

Bait harvesting in intertidal areas has increased on a global scale and is an important source of profits as a result of the increasing demand. In estuarine soft bottoms, this activity can have several impacts related to sediment disturbance through digging and trampling, which influences the biogeochemical cycles and the estuarine biological communities. In this context, the implementation of a management plan for bait harvesting is essential. Live bait (mainly polychaete annelids and sipunculids) and other macroinvertebrates, such as mollusks and crustaceans, are caught in many Portuguese brackish systems, and the catches are underestimated or even unknown. This is the case of polychaetes collected and used as live bait or as food supplement in aquaculture activities. The four main Portuguese estuarine systems were selected as study sites, under the project "LIVE BAIT - Annelid polychaetes as live bait in Portugal: harvesting, import and rearing management", funded by the PROMAR Program, in order to characterize this activity: Tagus (TE) and Sado (SE) estuaries and Ria de Aveiro (ACL) and Ria Formosa (FCL) coastal lagoons. Characterization of bait harvesting in intertidal areas was performed in each system by direct observations and by surveying bait collectors, with the aim of i) mapping the main bait harvesting areas, ii) identifying the main target species, techniques and tools used in this activity, and iii) estimating the harvesting effort (number of activity days and total quantities). Sampling was conducted during an annual cycle, from May 2015 to March 2016, divided in two periods: “summer” (May to October 2015) and “winter” (November 2015 to March 2016). These periods were chosen according to previous observations of more intense harvesting during spring and summer and to the closure period applied in SE for the capture of the polychaetes Marphysa sanguinea (Montagu, 1813), Diopatra neapolitana Delle Chiaje, 1841 and Hediste diversicolor (O.F. Müller, 1776) from 1 of November to 30 of April. Estimates of the number of harvesters were based on observations conducted at several sampling stations and boat itineraries, selected to cover the main intertidal areas used by bait harvesters at each estuary. Visual censuses were performed at each station, in order to count the number of persons harvesting in intertidal areas, with special interest in bait diggers, and to record the information regarding gender and age of harvesters, tools used to harvest, sediment type and the collected species. Random and focused interviews were conducted to all intertidal users and bait harvesters at each system, respectively. The first was performed in order to extrapolate the data for individuals whom activity was not possible to identify during observations. The second had the characterization of the community of bait harvesters as purpose. A logbook was produced and delivered to bait harvesters available to cooperate with the study, with the goal of estimating the bait biomass. In the logbook, bait diggers were asked to register their diary activity, regarding species caught, bait quantification (both in weight/biomass and number), tools used, and time spent during the harvesting. These logbooks were delivered to a maximum of five bait collectors in each estuarine system. Intertidal users were mainly harvesting bivalves and bait, except in TE where bait digging activity was residual. Globally, bait harvesters were mainly men (women were only abundant at SE), with ages between 40 and 60 years. The target bait species at TE, ACL and FCL was D. neapolitana, while M. sanguinea was the most harvested species at SE. Preferential areas for bait harvesting were determined and globally higher densities were observed during the “summer”, except at TE where “winter” recorded the highest values for density. Furthermore, differences in polychaete catches based on both the observed harvesters and the logbooks supported the differences among systems, with the highest amount of bait catches recorded at ACL (nearly 68 tons/year), followed by FCL (over 32 tons/year), SE (more than 28 tons/year) and finally, TE presented the lowest value (approximately 10 tons/year). The results of this study support the recommendation for the implementation of a national management plan for bait harvesting activities, with closure seasons implemented at all estuarine systems throughout the country, and especially those at which bait harvesting is more relevant.

Acknowledgements

This study had the support of Fundação para a Ciência e Tecnologia (FCT), through the strategic project UID/MAR/04292/2013 granted to MARE, and the PROMAR Program through the project 31-03-05-FEP-42: LIVE BAIT - Annelid polychaetes as live bait in Portugal: harvesting, import and rearing management.​

Keywords: Brackish systems, Bait capture, coastal management, Biological resources, polychaetes

Conference: IMMR | International Meeting on Marine Research 2016, Peniche, Portugal, 14 Jul - 15 Jul, 2016.

Presentation Type: Oral presentation

Topic: Fisheries and Management

Citation: Cabral S, Alves AS, Castro N, Fidalgo E Costa P, Sá E, Castro J, Cancela Da Fonseca L, Chainho P, Canning-Clode J, Picard D, Pombo A and Costa J (2016). Polychaete annelids as live bait in Portugal: harvesting activity in estuarine systems. Front. Mar. Sci. Conference Abstract: IMMR | International Meeting on Marine Research 2016. doi: 10.3389/conf.FMARS.2016.04.00111

Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters.

The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated.

Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed.

For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions.

Received: 23 May 2016; Published Online: 13 Jul 2016.

* Correspondence: Dr. Sara Cabral, MARE/ULisboa - Marine and Environmental Sciences Centre, Lisboa, 1749-016, Portugal, sdcabral@fc.ul.pt