A risk analysis of exotic trout in the Netherlands D. M. Soes P.-B. Broeckx Consultants for environment & ecology A risk analysis of exotic trout in the Netherlands D.M. Soes P.-B. Broeckx Commissioned by: Food and Consumer Product Safety Authority 9th of September 2010 Report nr 10-144 Status: Final report Report nr.: 10-144 Date of publication: 9th of September 2010 Title: A risk analysis of exotic trout in the Netherlands Author: Ir. D.M. Soes Ir. P.-B. Broeckx Number of pages without appendices: 96 Project nr: 09-761 Project manager: Ir. D.M. Soes Name & address client: Food and Consumer Product Safety Authority, Invasive Alien Species Team, P.O. Box 9102, 6700 HC, Wageningen Reference client: TRCPD/2009/3834 Signed for publication: General director Bureau Waardenburg bv drs. J.L. Spier Initials: Bureau Waardenburg bv is not liable for any resulting damage, nor for damage which results from applying results of work or other data obtained from Bureau Waardenburg bv; client indemnifies Bureau Waardenburg bv against third-party liability in relation to these applications. © Bureau Waardenburg bv / Food and Consumer Product Safety Authority This report is produced at the request of the client mentioned above and is his property. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, transmitted and/or publicized in any form or by any means, electronic, electrical, chemical, mechanical, optical, photocopying, recording or otherwise, without prior written permission of the client mentioned above and Bureau Waardenburg bv, nor may it without such a permission be used for any other purpose than for which it has been produced. The Quality Management System of Bureau Waardenburg bv has been certified by CERTIKED according to ISO 9001:2000. 4 Preface In the last few years, rainbow trout and brook charr have been found in streams known for their rare indigenous fish species, like brook lamprey and common minnow. To get more insight into the occurrence of exotic trout species in the Netherlands, the possibility of them becoming invasive, the possible ecological, economical and social impacts, and the possibilities of risk management the Invasive Allien Species Team of the Plantenziektekundige Dienst have commissioned Bureau Waardenburg to carry out a risk analysis. This risk analysis was carried out by Bureau Waardenburg: ir. D.M. Soes (project leader and report) ir. P.-B. Broeckx (report) M. Collier Msc (review) From the Team of Invasieve Exoten of the Food and Consumer Product Safety Authority the analysis was supervised by Mrs. dr. ir. José H. Vos and ir. J.W. Lammers. We would like to thank the following people for their effort and contribution: Franklin Moquette (Sportvisserij Nederland), Roger Meijs (BWZ), J.L. Spier (Bureau Waardenburg), Dietmar Firzlaff (aquaFUTURE), Willem Vergoossen (Roermond), Thijs Belgers (Roermond), I. Bogerd-Spijkerboer (Waterschap Veluwe), P. van Beers (Waterschap Veluwe), R. Neuteboom-Spijker (Waterschap Veluwe), Matthijs de Vos (Waterschap Rijn en IJssel), Rob Gubbels (Waterschap Roer en Overmaas), Tjeerd Dubois (Waterschap Rivierenland), Forellenkwekerij de Reijmer, Forellenkwekerij de Tipbosch, Forellenkwekerij Keijzersberg, Gerrit Hertgers (Forellenkwekerij ’t Smallert & ’t Hol), Hugo Verreycken (INBO), Paul Veenvliet, O. Haenen (CVI) Dr. Schäfer (LANUV NRW), B.O. Johnsen (Directorate for Nature Management, Trondheim, Norway) & L. Bachmann (The Natural History Museum, Department of Zoology, University of Oslo). 5 6 Table of contents Preface................................................................................................................................................5 Table of contents ...............................................................................................................................7 Samenvatting.....................................................................................................................................9 Summary..........................................................................................................................................13 1 Introduction .............................................................................................................................17 2 Overview salmonids in the Netherlands and Europe............................................................19 2.1 Indigenous species.......................................................................................................19 2.2 Salmonid aquaculture and first introductions in the Netherlands.............................22 2.3 Other exotic salmonid species in Europe ...................................................................23 2.4 Salmonid species considered.......................................................................................26 3 Biology and ecology of the rainbow trout..............................................................................27 3.1 Taxonomy.....................................................................................................................27 3.2 Description and identification......................................................................................28 3.3 Distribution....................................................................................................................28 3.4 Life history.....................................................................................................................33 4 Biology and ecology of the brook charr..................................................................................39 4.1 Taxonomy.....................................................................................................................39 4.2 Description and identification ......................................................................................39 4.3 Distribution....................................................................................................................41 4.4 Life history.....................................................................................................................47 5 Risk analysis...............................................................................................................................51 5.1 The probability of entry................................................................................................51 5.2 The probability of establishment .................................................................................60 5.3 The probability of spread.............................................................................................68 5.4 Endangered areas.........................................................................................................69 5.5 Impacts..........................................................................................................................72 5.6 Risk identification conform the Fisk method...............................................................80 6 Risk Management ...................................................................................................................81 6.1 Prevention of spread ....................................................................................................81 6.2 Eradication and physical control methods...................................................................83 7 Conclusions and recommendations.........................................................................................85 7.1 Conclusions...................................................................................................................85 7.2 Recommendations........................................................................................................87 8 Literature...................................................................................................................................89 7 APPENDICES....................................................................................................................................97 Appendix 1: Distribution data of the rainbow trout (Oncorhynchus mykiss) Appendix 2: Distribution data of the brook charr (Salvelinus fontinalis) Appendix 3: Fish Invasiveness Scoring Kit for the rainbow trout (Oncorhynchus mykiss) Appendix 4: Fish Invasiveness Scoring Kit for the brook charr (Salvelinus fontinalis) 8 Samenvatting Potentieel invasieve soorten De salmoniden zijn, zowel voor de consumptie als voor de hengelsport, erg gewild. Nadat de inheemse soorten sterk achteruitgingen is men in Europa gaan experimenteren met Noord-Amerikaanse soorten. Verschillende van deze soorten hebben habitateisen die niet in Nederland vóórkomen, met als grootste knelpunt de watertemperatuur van de Nederlandse wateren die in de zomer te hoog ligt. Alleen voor de bronforel en de regenboogforel kon op basis van hun habitateisen een kans op vestiging niet op voorhand worden uitgesloten. Van de bultrugzalm, de Chinookzalm, de Cohozalm, de beekridder en de Amerikaanse meerforel wordt niet verwacht dat ze zich kunnen vestigen in Nederland. Regenboogforel De regenboogforel is al in de 19e eeuw naar Europa gehaald en vanaf 1897 was ze ook aanwezig in de Nederlandse kwekerijen. In Nederland worden regenboogforellen vooral nog aangetroffen in de grotere rivieren, het IJsselmeer en enkele grotere, afgesloten wateren in het zuidwesten van Nederland. In het verleden is ze ook in kleine rivieren en beken waargenomen, zoals in Limburg en Brabant. Tegenwoordig wordt ze in