Gastropods and bivalves taken as by-catch in the deep-water shrimp trawl-fishery along the Pacific coast of Costa Rica, Central America

ABSTRACT

Deep-water habitats are among the least studied but most vulnerable environments. By-catch data from deep-water fisheries in Latin America are limited, and detailed reports on associated molluscs are scarce. This study provides information on deep-water shelled molluscs collected between 2010 and 2011 by commercial shrimp trawling fisheries along the Pacific coast of Costa Rica at depths from 112 to 271 m. Twenty-six species were identified, 23 gastropods and three bivalves. Our data extend the depth range of 14 species, and Homalopoma cf. grippii is reported for the first time for Costa Rica. The most common species were the gastropods Fusinus spectrum, Polystira nobilis and Solenosteira gatesi. Only one species (Sinum debile) was captured below 250 m. The catch of molluscs per unit effort was influenced by depth, but not by seasonality or geographic area. It is speculated that these long-lasting bottom-trawling activities have caused negative effects on species diversity and mollusc biomass. Nevertheless, a monitoring program is recommended to assess possible impacts of this type of fishery on mollusc diversity and biomass.

KEYWORDS:

• Bivalvia
• bottom-trawling
• continental shelf
• Eastern Tropical Pacific
• Gastropoda
• species richness

Acknowledgements

We are grateful to the company The Rainbow Jewels, S.A., Puntarenas, for their considerable support, which allowed us to monitor the deep-water resources of Pacific Costa Rica. Thanks go to the captains (Rigo and Esteban: ‘Mecate’), the crews of the shrimp trawlers Onuva and Sultana, and to René Diers, managing director of the company. We greatly appreciate the support of all the students who helped us with the collection and handling of the samples. Fiorella Vásquez provided logistic support cataloguing the specimens that were deposited at Museo de Zoología, Universidad de Costa Rica. Julian Schneider allowed us to use his photographs in Figures 4 and 5. We wish to thank Tayler M. Clarke and Jeffrey Sibaja Cordero for their help with statistical analyses. Raquel Romero Chaves elaborated the map in Figure 1. We are grateful to Tayler M. Clarke (University of British Columbia, Canada) for her linguistic revision of the manuscript. We greatly appreciate the valuable comments and suggestions received by the reviewers who carefully revised our manuscript and helped to improve its quality. ISW and YCG are thankful to SINAC-MINAET for approving their sampling permits (No. 181-2010-SINAC).

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

Financial support was made available from the German company Ristic AG, Oberferrieden, the Costa Rican company The Rainbow Jewels S.A., Puntarenas, and the University of Costa Rica (projects V.I. No. 111-A4-508, V.I., No. 808-A9-537, and No.808-B2-A49). Additional funding was provided by the ‘Program University – Enterprise for Sustainable Development ’ (PUEDES) of the Council of Central American Universities (CSUCA), the German Society for Technical Cooperation (GTZ), and the University of Kassel, Germany.