Furse, M.T.

Ibbotson, A.T.

Lowans, L.M.

Tapia, G.

English

NERC Open Research Archive

 The distribution of crayfish populations  in the River Thame in summer 1996               A. T. Ibbotson M. T. Furse G. Tapia  L. M. Lowans       Institute of Freshwater Ecology River Laboratory East Stoke Wareham  Dorset BH20 6BB  Tel: 01929 462314 Fax: 01929 462180    November 1996  The distribution of crayfish populations  in the River Thame in summer 1996    A. T. Ibbotson M. T. Furse G. Tapia  L. M. Lowans   Institute of Freshwater Ecology River Laboratory East Stoke Wareham  Dorset BH20 6BB Tel: 01929 462314 Fax: 01929 462180    November 1996    Environment Agency’s Project Leader Ms Julie Bywater Environment Agency Fobney Mead Rose Kiln Lane Reading RG2 0SF Tel: 01734 535000 Fax: 01734 311438   © Environmental Agency 1996  All rights reserved.  No part of this document may be produced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise without the prior permission of the Environment Agency.  The views expressed in this document are not necessarily those of the Environment Agency.  Its officers, servants or agents accept no liability for any loss or damage arising from the interpretation or use of the information, or reliance on views contained therein.   ii TABLE OF CONTENTS  Page  Executive summary          1               1. Introduction          2  2. Site description         2  3. Methods          3  4. Results          3                5. Discussion and recommendations       8           6. References          8  Annex A   Grid reference and site names of sites test trapped in August 1996  A-1  List of Tables  1 Numbers and mean size of crayfish captured at each site on the  River Thame, August 1996        7  List of Figures  1  The distribution and relative abundance of signal crayfish in the  River Thame, August 1996        4    2 The distribution and relative abundance of signal crayfish in the  River Thame below Thame, August 1996      5  3 The distribution and relative abundance of signal crayfish in the River Thame above Thame, August 1996      6    0 Executive summary  1.  Sixty sites on the River Thame and tributaries  were test trapped between 15 and 19 August 1996 to determine the distribution and presence of the white clawed crayfish Austropotamobius pallipes  (Lereboullet, 1858) and the signal crayfish Pacifastacus leniusculus (Dana, 1852).  2.  No white clawed crayfish were captured and no signal crayfish were captured above Long Crendon, or below Brookhampton.  Within their range the distribution of signal crayfish was discontinuous.  3.  Although the results of this survey were similar to a previous survey completed in November 1995, there is evidence of a gradual migration upstream.  This being 1.5km in 9 months.   2 1.  Introduction  In November 1995 a distribution survey of the crayfish populations in the River Thame was completed (Ibbotson, Furse & Dewey, 1995).  The primary objective of that survey system was to identify the most suitable reaches to be used for a detailed study into the impacts of  signal crayfish Pacifastacus leniusculus (Dana, 1852) on the flora and fauna of the River Thame.  A secondary objective was to ascertain whether native crayfish Austropotamobius pallipes (Lereboullet, 1858) were still present in the catchment or not.  During the study 36 sites were sampled.  These were  mostly on the main river channel but also in some of the major tributaries.  No native crayfish were found.  However, there was some doubt as to whether this was the result of the survey being completed during the cold winter months when crayfish activity is lowest and capture most difficult.  For this reason and because some of the tributaries had not been sampled the survey was repeated during the summer of 1996 and over a more extensive range.  This was felt to be important because native crayfish had been reported as present in the Thame catchment as recently as 1992 in the Milton Ditch and between 1988 and 1990 at Notley Abbey (NRA Biologists Reports).   2. Site description  The River Thame runs from just north of Aylesbury, through Thame to join the River Thames south of Oxford.  It is approximately 60 km in length and for the greater part it drains improved pasture.  Its proximity to the two conurbations of Aylesbury and Thame and the use of the adjacent land for pasture, means there is pressure to manage the river for flood control purposes.  The greater part of the river is embanked and dredged approximately every 5 years to reduce the risk and incidence of flooding.  This type of flood relief management will have had deleterious effects on the distribution of crayfish in the River Thame, as it makes the habitat less suitable for these animals (Hogger, 1988).  Once the river flows past Aylesbury it is used extensively for coarse fish angling.  The anglers find the signal crayfish a nuisance because they remove bait from hooks.  This is particularly a problem when the crayfish are numerous and angling organisations have been known to ask commercial crayfishermen to reduce the density of crayfish.  There is considerable exploitation of the signal crayfish population.  Much of the river between Thame and Chippinghurst Manor is fished commercially.  These activities are dominated by one commercial fisherman.     3 3. Methods  Between 15 and 19 August 1996, 60 sites between the source of the River Thame and its confluence with the River Thames were test trapped for the presence of crayfish.  The sites included the main river and most of its major tributaries (Figs 1-3; Annex A).  Test trapping involved placing 4 disinfected baited traps in the river, leaving them overnight and recovering them the next day.  There were two sizes of traps (mesh size 15mm  and 30mm) and two of each size were used.  Crayfish captured inside the traps were counted, identified and measured.  One of three categories of abundance were assigned to each site depending on the number of crayfish captured in each trap.  These categories were absent, less than 5 per trap and between 5 and 9 per trap.   4. Results  No white clawed crayfish were captured and no signal crayfish were captured above Long Crendon (NGR SP 707 078), or below Brookhampton (NGR SU 598 977).  The distribution was discontinuous with crayfish being captured in small pockets but being apparently absent in adjacent sites (Fig 1-3).  There were a few tributaries with large crayfish populations, notably the Haseley Brook (Sites 30 & 32, Fig 2) and the Peppershill Brook (Site 56, Fig 2).  Smaller populations were shown to be present in the Gainsbridge Brook (Site 31, Fig 2), Milton Ditch (Site 58, Fig 2), Worminghall Brook (Site 54, Fig 2), Tiddington Brook (Site 15, Fig 2), Cuttle Brook (Site 53, Fig 2) and the Scotsgrove Brook (Site 10, Fig 3).  In general, the distribution of signal crayfish was very similar to that found in the survey of November 1995.  However the upstream limit appears to have moved from Thame to Long Crendon (approx 1.5km) between the two surveys and crayfish were found in the Scotsgrove Brook above Thame. Key o no crayfish • <5 per trap • 5-9 per trap ~JI ~] '.-'.1 l~1 ii.. ~!.Ii , ,.I 5km I I Figure 1. The distribution and relative abundance of signal crayfish in the River Thame, August 1996 4 ," 11 ..I N Dorchester\, Key o no crayfish •	 <5 per trap 1km.5-9 per trap Figure 2. The distribution and relative abundance of signal crayfish in the River Thame below Thame, August 1996. 5 i .... ~j .. tL._.: '"--".~~"'" !' -'"1'1 '-0 -"'-O(JQ O\C Key " ....(1) o no crayfish ~ ;J • <5 per trap (1) 0-r;;" 5. .5-9 per trap 0" S. o' ::l ~ ::l 0- .... ~ ~ ::" < (1) ~ 0" C ::l 0-~ ::l n (1) 0 ...., rJl 0\ riQ' ::l e:- n ; '< ::tl rJl ::r :;. S- (1) ;;0 :<" (1) .... ;J pO 3 (1) ~ 0" 0 < (1) ;J ~ 3 .(1) ;J> c (JQ c 1 ' 5km , I ~   7 Table 1 Numbers and mean size of crayfish captured at each site on the River Thame, August 1996   Site Number  Grid Reference  Average Number per Trap  Average Carapace Length (mm)  1  SP 782 161  0  -  2  SP 797 154  0  -  3  SP 815 153  0  -  4  SP 771 135  0  -  5  SP 751 123  0  -  6  SP 729 111  0  -  7  SP 723 101  0  -  8  SP 709 100  0  -  9  SP 714 088  0  -  10  SP 711 070  0.5  5.4  11  SP 707 078  1  5.8  12  SP 693 066  0  -  13  SP 685 067  1  5.45  14  SP 669 070  6  6.0  15  SP 649 058  4.5  4.1      16  SP 652 065  1.5   4.3  17  SP 632 055  7  5.2      18  SP 612 048  0.5  3.7    19  SP 618 051  0  -  20  SP 614 082  0  -  21  SP 611 031  0  -  22  SP 605 039  0  -  23  SP 599 017  0    -   24  SP 602 014  2   3.5    25  SP 578 011  0  -  26  SU 596 996  3.5  6.0  27  SU 576 984  0  -  28  SU 598 985  0.5  3.4  29  SU 627 977  0  -  30  SU 627 993  6   4.9    31  SP 615 005  1.5  4.1  32  SP 612 001  8.5  4.3      33  SU 598 977  1    5.95     34  SU 599 955  0  -  35  SU 580 936  0  -  36  SP 700 065  6   4.25     37  SP 846 176  0  -  38  SP 879 176  Dry  -  39  SP 884 168  0  -  40  SP 828 209  0  -   8  Site Number  Grid Reference  Average Number per Trap  Average Carapace Length (mm)  41  SP 806 187  0  -  42  SP 830 103  0  -  43  SP 776 096  0  -  44  SP 785 083  Dry  -  45  SP 792 042  0  -  46  SP 779 029  0  -  47  SP 769 023  Dry  -  48  SP 735 064  0  -  49  SP 751 077  0  -  50  SP 739 105  Dry  -  51  SP 712 130  Dry  -  52  SP 679 141  Dry  -  53  SP 702 060  1  5.75     54  SP 647 083  0.5   5.1  55  SP 659 074  Dry  -  56  SP 661 071  5  4.3  57  SP 618 043  0  -  58  SP 625 034  0.5  4.9  59  SP 635 036  Dry  -  60  SP 712 046  0  -   5. Discussion  The absence of any native crayfish at any of the sites would suggest that native crayfish are now extinct from the River Thame and its tributaries.  It is not certain what the causes of this extinction are, particularly in the upper reaches because the distribution of signal crayfish extends to no further upstream than Long Crendon.  In the absence of disease the native species ought to be able to survive in upstream reaches where signals are absent.  It is however possible that the disease has been transported upstream by other vectors which could include angling equipment, crayfish traps, dredging equipment, birds, fish or other animals.  The distribution of signal crayfish is not very different from the distribution described in the survey completed in November 1995.  It remains discontinuous throughout the main river channel.  This is probably the result of two major influences; these being the sites of original successful introduction where crayfish have spread from and the regular dredging activities which reduce the populations locally.  There is evidence of a gradual process of upstream migration and colonisation, with the upstream limit of their distribution moving from Thame Bridge to Long Crendon about 1.5 km upstream.  If this migration and colonisation continues, and there is no reason to suppose that it will not, then there are likely to be increased pressures for the commercial fishery to be extended to other areas.       9 6. References  Hogger, J. B. (1988) Ecology, population biology and behaviour. In Freshwater crayfish: biology, management and exploitation, edited by D.M. Holdich and R. S. Lowery, 114-144. London: Croom Helm.  Ibbotson, A. T., Furse, M. T. & Dewey, K.  1995.  The distribution and baseline survey of the crayfish populations in the River Thame.  Report to the National Rivers Authority, Thames Region, 9pp.   Annex A. Grid references and site names of sites test trapped in August 1996.   1 SP 782 161 Berryfields Farm     Putlowes Tributary  2 SP 797 154 Quarrendon House Farm    River Thame  3 SP 815 153 Elmhurst      Thistle Brook  4 SP 771 135 Eythrope Park     River Thame  5 SP 751 123 Mainshill Farm     River Thame  6 SP 729 111 Cuddington Mill Farm    River Thame  7 SP 723 101 Chearsley     River Thame  8 SP 709 100 Railway Embankment    Notley Abbey Tributary  9 SP 714 088 Notley Abbey     River Thame 10 SP 711 070 Scotsgrove House     Cuttle Brook 11 SP 707 078 Works      River Thame 12 SP 693 066 Thame Bridge     River Thame 13 SP 685 067 North Weston     River Thame 14 SP 669 070 Shabbington     River Thame 15 SP 649 058 Tiddington     Tiddington Tributary 16 SP 652 065 Draycot      River Thame 17 SP 632 055 Waterstock     River Thame 18 SP 612 048 A40 Crossing     River Thame 19 SP 618 051 Helton Mill     Holton Brook 20 SP 614 082 Parsons Farm     Holton Brook 21 SP 611 031 Cuddesdon Mill     River Thame 22 SP 605 039 Castle Hill     Cuddesdon Brook 23 SP 599 017 Chippinghurst Manor    Denton Brook 24 SP 602 014 Chippinghurst Manor    River Thame 25 SP 578 011 Toot Baldon     Baldon Brook 26 SU 596 996 Chiselhampton     River Thame 27 SU 576 984 Marylands Farm     Baldon Brook 28 SU 598 985 Stadhampton     Chalgrove Brook 29 SU 627 977 Nr Langley Hall     Chalgrove Brook 30 SU 627 993 Cowlease Copse     Haseley Brook 31 SP 615 005 Little Milton     Gainsbridge Brook 32 SP 612 001 Coldharbour     Haseley Brook 33 SU 598 977 Brookhampton     River Thame 34 SU 599 955 Lower Grange     River Thame 35 SU 580 936 Bridge End     River Thame 36 SP 700 065 Thame Island     River Thame 37 SP 846 176 Rowsham Bridge     Rowsham Brook  38 SP 879 176 Nr. Thistle Brook Farm    Thistle Brook 39 SP 884 168 Whitwell Farm     Unnamed 40 SP 828 209 Hardwick Bridge     Hardwick Brook  41 SP 806 187 Hardwick Brook     Hardwick Brook 42 SP 830 103 Nr. Stoke Mandeville    Wendover Brook 43 SP 776 096 Nr. Ford      Scotsgrove Brook 44 SP 785 083 Nr. Lower Waldridge Farm    Scotsgrove Brook 45 SP 792 042 Nr. The Mill     Cuttle Brook 46 SP 779 029 Nr. Pitch Green     Cuttle Brook 47 SP 769 023 Nr. Henton     Cuttle Brook 48 SP 735 064 Nr. Tythrop House     Unnamed 49 SP 751 077 Nr. The Manor     Unnamed 50 SP 739 105 Nr. Dad Brook House    Dad Brook 51 SP 712 130     Musk Hill Farm     Unnamed 52 SP 679 141 Dorton      Unnamed 53 SP 702 060    Thame      Cuttle Brook 54 SP 647 083 Worming Hall     Worminghall Brook 55 SP 659 074 Little Ickford     Peppers Hill Brook 56 SP 661 071 Little Ickford     Peppers Hill Brook 57 SP 618 043 Unknown    Milton Ditch 58 SP 625 034 Nr. Great Milton     Milton Ditch 59 SP 635 036 NNE Great Milton     Milton Ditch 60 SP 712 046 Thame      Cuttle Brook        DISTRIBUTION SHEET  To be completed by all Project Leaders completing commissioned research project reports.  Please bind a copy of this distribution sheet as the final page in all internal (IFE) copies of the report.  1. Title: The distribution of crayfish populations in the River Thame in summer 1996    Authors: A T Ibbotson, M T Furse, G Tapia and L Lowans  Report ref: T04073N7/6  Master copy held by: M T Furse  Report access code:C  2. DISTRIBUTION LIST [A)-H) standard, I) other] No.copies Date A) Contract customer:   5 14-11-96 B) Director - Prof A.D. Pickering  1 14-11-96 C) Asst Director - Dr J. Hilton (title page and abstract only)  14-11-96 D) River Laboratory Library  1 14-11-96 E) Windermere Library  1 14-11-96 F) Val Palmer (title page only + no.pages for adding to publication list)   G) Project leader:   M T Furse  2 14-11-96 H) Other (list below and indicate no.copies in RH column)    1. A T Ibbotson  1 14-11-96  2. M T Furse  1 14-11-96  3. G Tapia  1 14-11-96  4. L Lowans  1 14-11-96   Total number of copies made  14    REPORT ACCESS CODES  S In strict confidence - restricted access - Access to named customer(s) - (could be named restricted access individuals), IFE Directorate, Project Leader and all authors.  C In confidence - restricted access - Access to customer, IFE Directorate, Project Leader, all authors, and IFE staff with permission of Project Leader.  N ‘Normal’ access - Access to customer and all IFE staff.  Access to visitors and general public with permission of Project Leader.  G General access - General access to anyone as required.  

Ecology, population biology and behaviour. In Freshwater crayfish: biology, management and exploitation, edited by D.M. Holdich

The distribution and baseline survey of the crayfish populations in the River Thame. Report to the National Rivers Authority,

The distribution of crayfish populations in the River Thame in summer 1996

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The distribution of crayfish populations in the River Thame in summer 1996

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