The abundance, movement and site fidelity of the adult whelk, Buccinum undatum, in the territorial waters of the Isle of Man A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science (MSc) in Marine Environmental Protection Bangor University 2015 Matthew Robinson BSc Marine Biology (2010, University of Liverpool) School of Ocean Sciences, Bangor University, Menai Bridge, Anglesey, LL59 5EY, UK www.bangor.ac.uk [email protected] Submitted in September, 2015 DECLARATION This work has not previously been accepted in substance for any degree and is not being currently submitted for any degree. Candidate: Date: 18/09/2015 This dissertation is being submitted in partial fulfillment of the requirement of the MSc in Marine Environmental Protection. Candidate: Date: 18/09/2015 The dissertation is the result of my own independent work / investigation, except where otherwise stated. Candidate: Date: 18/09/2015 I hereby give consent for my dissertation, if accepted, to be made available for photocopying and for inter-library loan, and the title and summary to be made available to outside organisations. Candidate: Date: 18/09/2015 Acknowledgements I would like to thank Professor Michel Kaiser, Dr Isobel Bloor and Sam Dignan for their support and guidance during the project. I am immensely grateful to Jon Jo Skillen, skipper of ‘Boy Shayne’, and Jordan Corkill for their efforts and enthusiasm for making the project a success. Thank you also to Lucy May for her help during the tag making and tagging phase of the project, and for her support throughout. The abundance, movement and site fidelity of the adult whelk, Buccinum undatum, in the territorial waters of the Isle of Man Abstract The maximum and daily movements of the common whelk (Buccinum undatum) were investigated in Ramsey Bay, northeast Isle of Man from June to July 2015. A mark- recapture study to estimate abundance was conducted by tagging 5000 B. undatum in five different series and releasing them at separate sites in the area of study. B. undatum abundance, above and below the minimum landing size, and Catch Per Unit Effort (CPUE) were estimated and were analysed for differences between different pot types and pot soak times. The population abundance for each series was estimated using the Lincoln-Petersen Index, and the density of B. undatum was determined based on the area created by the distribution of tagged B. undatum from the release points. A total of 772 B. undatum were recaptured, a 15.4% recapture rate. Mean CPUE was 3.57 kg pot-1 and there was no significant difference in CPUE between lay-down and stand-up pot designs, or between pot soak times of 24, 48 and 72 and over hours. The population density of the study area was estimate to be 2.68 m-2, the mean maximum distance travelled was 155.9 m and the mean daily distance travelled was 15.2 m. Table of Contents 1. INTRODUCTION ................................................................................................... 1 1.1. Distribution and movement ............................................................................. 2 1.2. Feeding and nutrition ....................................................................................... 2 1.3. Growth ............................................................................................................... 3 1.4. Reproduction and life history .......................................................................... 3 1.5. Predation ........................................................................................................... 4 1.6. Buccinum undatum fisheries ............................................................................ 4 Relevance of Buccinum undatum fisheries .............................................................. 4 Current regulations and management ....................................................................... 5 By-catch .................................................................................................................... 5 1.7. Mark-recapture in Buccinum undatum .......................................................... 6 Examples of mark-recapture in Buccinum undatum ................................................ 6 1.8. Aim ..................................................................................................................... 7 1.9. Hypotheses ......................................................................................................... 7 2. METHODS .............................................................................................................. 9 2.1. Logistics ............................................................................................................. 9 Study area ................................................................................................................. 9 Work vessels ........................................................................................................... 10 Fishing gear ............................................................................................................ 10 2.2. Mark-recapture study .................................................................................... 11 Tag Design .............................................................................................................. 11 B. undatum tagging ................................................................................................ 12 Recapture period ..................................................................................................... 14 2.3. Data Analysis .................................................................................................. 14 Catch per unit effort (CPUE) .................................................................................. 14 Pot type ................................................................................................................... 14 Soak time ................................................................................................................ 15 2.4. Mark-recapture .............................................................................................. 15 Lincoln-Petersen Index ........................................................................................... 16 Population density .................................................................................................. 16 Daily distance travelled .......................................................................................... 17 3. RESULTS ............................................................................................................... 18 3.1. Pot type ............................................................................................................ 18 3.2. Soak time ......................................................................................................... 20 3.3. Mark-recapture study .................................................................................... 21 Release and recapture points .................................................................................. 21 Population density and abundance ......................................................................... 23 Distance travelled ................................................................................................... 24 4. DISCUSSION ........................................................................................................ 24 4.1. Catch per unit effort ....................................................................................... 24 4.2. Pot type and soak time ................................................................................ 25 4.3. Mark-recapture to estimate abundance ....................................................... 25 4.4. Lincoln-Petersen Index .................................................................................. 26 4.5. Recapture rate ............................................................................................. 26 4.6. Minimum and daily distance travelled ...................................................... 27 4.7. Limitations ...................................................................................................... 27 5. REFERENCES ...................................................................................................... 29 List of Figures Fig 1. The common whelk, Buccinum undatum. Fig. 2 Survey area off Ramsey bay in the northeast of the Isle of Man where the mark- recapture study on Buccinum undatum was conducted from 16th June – 19th July 2015, just outside the 3 NM limit indicated by the black line. Fig. 3 The commercial potting vessel ‘Boy Shayne’ used for the recapture period of the mark-recapture study of Buccinum undatum to estimate abundance and movement in Ramsey Bay, northeast Isle of Man from 17th June – 19th July. Fig. 4 Pots used by the commercial potting vessel ‘Boy Shayne’ to capture Buccinum undatum throughout the mark-recapture study in Ramsey Bay, northeast Isle of Man from 17th June – 19th July. a) A 36 litre round, plastic moulded pot with netting drawn closed at the top. b) A 20 litre lay-down pot with netting drawn closed at the top. Fig. 5 The tag design used in the mark-recapture study of Buccinum undatum in Ramsey Bay, northeast Isle of Man from 17th June – 19th July. a) Embossed plastic label with a unique code, b) thick rubber lobster claw band of width 10 mm, diameter 20 mm and thickness 1 mm and c) the complete