the quantity of lead shot, nylon fishing line and other litter discarded at a coarse fishing lake
TRANSCRIPT
Biological Conservation 38 (1986) 21-34
The Quantity of Lead Shot, Nylon Fishing Line and Other Litter Discarded at a Coarse Fishing
Lake
Irven J. Forbes*
Llysdinam Field Centre, UWIST, Newbridge-on-Wye,iPowys, Wales, Great Britain
ABSTRACT
In order to assess the impact of angling on the environment an attempt was made to estimate the quantity of angler litter present around a popular coarse fishery. The lake bank was divided into nine site categories which had experienced different degrees of angler pressure. Lead shot, nylon line and general litter were collected from sampling points within these sites and used to estimate total quantities around the lake. In total 41 000 +_ 14 000 lead shot, 57 + 21 km (96 000 +_ 35 000 pieces) of nylon line and 106 m 2 (5552 pieces) of general litter were estimated to occur on the entire lake bank. The vast majority of lead shot, nylon line and general litter was present in close proximity to fishing points and these areas contained the highest litter densities, with lead shot up to 137 pieces m -2, nylon line up to 188 pieces m -2 (173m m -2) and general litter up to 4 pieces m-2, (2900 cmZ m-2). It was concluded that anglers discarded the majority of the lead shot and nylon line pieces during tackle manipulations and that anglers were also the source of a substantial quantity of the general litter which creates a large visual impact on the lake environment.
I N T R O D U C T I O N
In recent years nature conservation organisations have expressed concern over the potential harm angling could be causing to the environment.
* Present address: Anglian Water, Lincoln Division, Waterside House, PO Box 62, Waterside North, Lincoln LN2 5HA, Great Britain
21 Biol. Conserv. 0006-3207/86/$03-50 © Elsevier Applied Science Publishers Ltd, England, 1986. Printed in Great Britain
22 lrven J. Forbes
Research has been conducted into certain aspects of the sport including the direct disturbance of waterfowl (Cooke, 1976) and otters (Macdonald et al., 1978) by anglers, the removal of wildlife habitat to facilitate angling (Liddle & Scorgie, 1980) and the shot and line discarded by anglers (Bell et al., 1985).
Angling litter is here regarded as any material discarded on the lake bank by an angler and so includes general items such as tin cans and plastic bags, as well as specific angler items such as split lead shot, monofilament nylon fishing line, fishing floats, fishing bait bags, etc. Any such item discarded on a lakeside or river bank not only represents a hazard to wildlife, but it also reduces the visual beauty of the area and has the potential to damage the reputation of the sport. In recent years the well-documented problem of lead poisoning amongst bird populations, particularly in swans (Simpson et al., 1979; Birkhead, 1981, 1982; Nature Conservancy Council, 1981) but also other waterfowl (Thomas, 1980), has resulted in widespread concern.
This study was undertaken with the aim of providing basic information on the quantity of litter present around Llandrindod Wells Lake, a coarse fishery in Mid-Wales. Angling is popular at the Lake with 2400 fishing tickets (day, week, and season tickets) sold between May and October 1981 (Harrison et al., 1982) but it is probable that other visitors (walkers, etc.) occur in greater numbers. Visitors to the Lake were regarded either as 'anglers' or 'general visitors' and the litter pressure from both groups was investigated. Particular importance was placed on the estimates of lead shot and nylon line because of their connections with wildlife mortality. An attempt was also made to estimate the visual impact of general litter items at the Lake.
METHODS
Fieldwork was restricted to the summer months of 1983 when the low water level ensured that the maximum area of bank was exposed during sampling. The lakeside (Fig. 1) was classified into nine separate site categories. Each site category comprised areas of bank which were expected to have had similar histories of general and/or angler pressure.
Anglers fished from purpose-built wooden platforms ('wood pegs') both on the island edge (category 1) and on the lake edge (category 2). They also fished from areas easily accessible to the water's edge termed
Litter discarded by fishing lake 23
No Fishing
Wooden fishing platform (Cete.l&2)
Open fishing area(cat.3)
~ Encircling roadway (Cat=.4&5)
Mown grass (,c=t.6)
~ Overgrown vegetation (cot=.T&8)
~ Thick overgrown vegetation (Cat.9)
Fig. 1.
lOOm. Llandrindod Wells Lake showing the distribution of fishing points and the
types of ground cover.
24 Irven J. Forbes
'open pegs' (category 3), which occurred only on the lake edge. Fishing from boats was not permitted and anglers were the only visitors allowed on the island.
Pressure from general visitors to the Lake was concentrated on areas of mown grass (category 6) and on the roadway encircling the lake perimeter (category 5). Areas of roadway directly adjacent to fishing points were regarded as a separate category (category 4), as they were expected to have experienced pressure from both anglers and general visitors.
Neither anglers nor general visitors were expected to have exerted much pressure on unmanaged sections of bank on the island (category 7) or on the lake edge (category 8). Areas with thickly overgrown vegetation and poor accessibility (category 9) were expected to have experienced the least pressure from visitors.
Within each site category, 10 sampling points were randomly posi- tioned. In categories 1, 2 and 3 these sampling points were centred on randomly selected fishing points. In category 4 the sampling points were positioned directly adjacent to 10 fishing points which were randomly selected from all fishing points that bordered the encircling roadway. At each sampling point a circular area of 20 m 2 was designated and all visible litter within this area was collected. Within each of these areas two circular sampling areas (each with an area of 0.5 m 2) were randomly positioned and these were intensively searched for 30 min to a depth of 20 mm for lead shot and nylon fishing line. At site categories 1 and 2 two additional 0.5 m 2 sampling areas were randomly positioned on the actual wooden platforms. In initial 'mark and recapture' tests the efficiency of lead shot collection from the upper 20 mm of the sampling areas was 84%.
The approximate boundaries of the nine site categories were deter- mined so that their surface areas could be calculated and used with litter densities to estimate the total quantity of litter discarded around the Lake. The boundaries of categories 1, 2 and 3 (sites of high angler activity) were not discrete so the spread of shot and line around five randomly selected fishing points was investigated. At each of these fishing points two transects were positioned (one parallel, the other perpendicular, to the lake edge) such that they intersected in the centre of the fishing point and extended half-way to neighbouring fishing points or to the discrete boundary with other site categories. At 1-m intervals along these transects 0.5 m 2 circular sampling areas were searched to a
Litter discarded by fishing lake 25
depth of 20 mm for shot and line. The percentages of shot and line outside the 20 m 2 circular sampling areas could then be estimated and the appropriate corrections made.
RESULTS
Angling litter
The mean number of lead shot, pieces of nylon line and other angler items, as well as the mean length of nylon line per unit area, were calculated for each site category. At site categories 1, 2 and 3 the estimated numbers of shot and line and the estimated length of line were corrected by 5%, 19% and 25%, respectively, to account for items outside the 20 m 2 sampling areas (Fig. 2). The shot results were also corrected to account for the estimated collection efficiency of 84%. It was estimated that altogether 41374 + 1 3 9 5 1 pieces of shot, 56 580 _ 21 160 m (96454 _ 35 092 pieces) of line and 356 other angler items (i.e. fishing floats, bait bags and other specific angling items) were discarded on the banks of the Lake and its island (Table 1).
v Lead shot • NyLon Length o Nyton number
Radius (m)
0 1"5 3"5 5"5 , , , , i J
100'
80
Cumulative 60 %
4.0
20
t , ,
0 I00
Area (m z)
Fig. 2. Cumulative percentage increase for the number of lead shot and nylon line pieces, and the length of nylon line, with increasing size of the circular sampling area.
TA
B].
E 1
T
he T
ota
l Q
uant
itie
s o
f A
ngle
r L
itte
r D
isca
rded
at
the
Nin
e S
ite
Cat
egor
ies
(__
95%
con
fide
nce
lim
its)
tO
O~
Site
cat
egor
y T
otal
L
ead
shot
N
ylon
lin
e O
ther
ang
ler
item
s ar
ea
(m)
Mea
n T
otal
M
ean
Mea
n T
otal
T
otal
M
ean
Tot
al
dens
ity
num
ber
dens
ity
leng
th
num
ber
leng
th
dens
ity
num
ber
(m-
2)
(m-
2)
(m)
(m)
(m-
2)
1 O
n p
latf
orm
48
-75
90.3
A
rou
nd
pla
tfor
m
451.
25
21-2
2 O
n p
latf
orm
49
-5
27-4
A
rou
nd
pla
tfor
m
610.
5 14
.2
3 88
4 17
.3
4 17
4 0-
7 5
737
0 6
2 05
6 0
7 1 4
50
0
8 2
866
0 9
2 29
4 0
Tot
als
11 6
21
--
4622
+ 8
39
12-8
0-
32
743
+ 2
36
250
+ 1
56
] 10
045-
t-
82-6
0.
91
4435
5-1-
42
398_
+
j~ 0
-25
125
2708
14
783
15
841
1
42
4+
48
1
5-0
0.07
29
5___
117
22
___ 1
2 "]
91
03 _
+ 21
.0
0-39
15
257
-I-
62
50__
jg
0.1
9 12
5 35
41
5428
3
205
16
05
8+
32
.2
0.21
3
38
73
+
74
72
+
0-07
62
62
77
12 5
97
1 77
9 12
2___
105
1.
1 0.
53
191
+_ 1
91
101
4-80
0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
1-2
0.05
1
740_
+ 87
3 +
287
0-
03
44
1740
0
0 0
0 0
0 0
0 0
0 0
0 0
0 41
37
4+
--
--
9
64
54
+
5658
04-
--
356
1395
1 35
092
21 1
60
Litter discarded by fishing lake
300-
27
No. of
Shot
250-
200"
150"
I00-
r~ger SSO AA BB 2 5
Shot Size
IFI. 7 O 9
Fig. 3. Frequency histogram of lead shot sizes collected at Llandrindod Wells Lake.
The length of bank around the lake and the island was approximately 1140 m and it was estimated that there were 36 + 12 pieces of shot and 50 + 22 m (85 + 31 pieces) of line per metre of bank. However, most angler litter was concentrated into site categories 1, 2 and 3 (Table 1). The 'wood peg' category on the island (category 3) contained the highest density of all types of angler litter (Table 1) as well as significantly longer pieces of nylon than any other site category (P < 0.025). Category 3 also produced the sample with the highest density of shot (137 pieces m -2) and line (i88 pieces m -2, measuring 173 m) recorded at the Lake. Lead shot densities were significantly higher on wooden platforms than around them, both at the lake edge (P<0.02) and on the island (P < 0.001).
All shot sizes ranging from ledgers to size 9 were collected; BB represented the most numerous size (Fig. 3). The average weight of shot was calculated to be 0.81 g using standard manufactured weights, and the total weight of shot discarded around the lake was estimated to be 33.5 + 11.3 kg. The average length of nylon discarded at the Lake was 56 cm but the length frequency distribution was skewed towards shorter lengths with 50% being shorter than 25 cm and 5-10 cm being the most
28 lrven J. Forbes
180.
160"
1/+0-
120"
No of 100" nyton pieces
80.
60-]
60
20
1 6
" m & • r / • - • x ' l . - - - r • _ ~ ' - i ~ - - n ,..rl
0~5 1!0 1~5 2"0 2!5 3!0
Length (rn)
3r5 ~.0
Fig. 4. Frequency histogram of the nylon lengths collected at Llandrindod Wells Lake. Nylon lengths with shot attached are shown (m) (18 pieces collected were longer than
4.0 m; the maximum length collected was 11.0 m).
c o m m o n size range (Fig. 4). Of all the shot collected 13% was at tached to nylon line and of this at tached shot 50% was on pieces less than 50 cm in length (Fig. 4). Most hooks which were at tached to nylon were also on lengths of less than 50 cm.
General litter
Nine types of general litter were recognised and for each type the number of litter items and their total surface area were determined for all site categories (Table 2). The surface area of an item was calculated by multiplying its max imum height by its max imum width.
It was estimated that 5552 general litter items with a total surface area of 106 m 2 were present a round the Lake. Plastic articles appeared to be most numerous and had the largest surface area, but paper was
TA
BL
E 2
T
he A
mo
un
ts o
f G
ener
al L
itte
r in
Eac
h S
ite
Cat
egor
y at
the
Lak
e (a
) Su
rfac
e ar
ea (
cm 2)
and
tot
al n
umbe
r o
f it
ems
of
each
typ
e o
f li
tter
per
squ
are
met
re i
n sa
mpl
ed a
reas
Typ
e of
litt
er
Site
cat
egor
y
1 2
3 4
5 6
7 8
9 Su
rfac
e ar
ea (
cm m
- 2)
Pla
stic
93
1 "3
6 24
7.87
10
0.04
9.
45
2.27
2.
00
11-4
4 5.
75
0"85
P
aper
53
.88
28-2
0 73
-35
! 1.9
6 2-
45
1.20
0-
58
1-46
0
Fab
ric
67.1
9 34
-04
19.8
2 0
0.18
0
0 0.
35
0 M
etal
34
-89
33-1
1 18
.56
1-47
0.
02
0"02
3.
23
0-01
0.
98
Gla
ss
19.8
8 3-
20
6.38
0-
33
0 0
4-64
1-
50
1'60
~.
S
trin
g 0
7.65
0.
47
0-03
0
0 0
0 0
Ru
bb
er
3-26
0.
03
0-03
0
0 0
0 0
0 ~"
W
oo
d
0 0.
13
0.11
0-
24
0.16
0.
01
0 0.
07
0 ~
. O
ther
s 0
0-05
0-
10
0.24
0.
28
0 0
0-03
0
Tot
al
1 ! 1
0.46
35
4-28
21
8-86
23
.72
5.36
3.
23
19.8
9 9-
17
3-43
Nu
mb
er o
f it
ems
(m -2
) 2-
24
1.42
i.
70
1.01
0.
59
0-21
0.
14
0-22
0.
05
Mea
n si
ze (
cm 2
) 49
6 24
3 12
9 24
9
15
142
41
69
(b)
Est
imat
ed t
otal
s pr
esen
t at
the
Lak
e
Lit
ter
char
acte
rist
ic
1 2
3 4
5 6
7 8
9
Sur
face
are
a (m
2)
55.5
22
-8
19-4
0-
4 0-
4 0.
7 2-
9 2.
6 0.
8
Nu
mb
er o
f it
ems
1120
93
7 15
03
176
435
432
203
631
115
t~
30 lrven J. Forbes
-5'o
r - ,
g
1 t C \
\
/ •9 g
f 5 \ \
\ ,J
- 2 0 a - -
f 2 D ~ ~-
" - - - - J
s'o lbo Dimension I
A=High general visifor pressure,
B--Low angter and tow general visitor pressure
[ =Partial angler pressure
D =High angler pressure.
Fig. 5. Two-Dimensional Polar Ordination plot of the nine site categories using the surface area measurements of the collected litter types.
also present in a substantial quantity. Site categories 1, 2 and 3 contained the majority (64% by number and 93% by surface area) of the general litter at the Lake despite their small proportionate area of the bank (18%). Site category l 1 contained the highest mean density of items (2.24 items m-2; 1110-46 cm 2 m -2 surface area) as well as the maximum density recorded for any site (4 items m-2; 2900 cm 2 m-2). Twenty- five per cent of the general litter discarded around all fishing points and 48% of the litter at site category 7 were items whose contents were commonly used for bait by anglers at the Lake.
Two-Dimensional Polar Ordination using Czekanowski's coefficient was employed to make a visual summary of the data shown in Table 2a, following the method of Gauch (1982). The technique organised the site categories into 4 discrete groups, A-D (Fig. 5). Group A, areas most frequently used by general visitors, showed a low density of small pieces of litter. Group B, areas on the lake edge with poor access, showed very low densities of small items. Group D, the areas from which anglers actually fished, showed a very high density of large litter
Litter discarded by fishing lake 31
items. Group C contained site categories 7 and 4. Site category 7, an area of poor accessibility but bordering island fishing points, showed small numbers of relatively large items. Site category 4, areas adjoining fishing points on the lake edge, showed a greater number of much smaller items.
DISCUSSION
Very few studies have been undertaken to estimate the quantity of angler litter in the environment. Members of the Young Ornithologist Club (YOC) undertook a basic survey of angler litter throughout Britain and found Trawsfynydd Lake, where 5.6 km of nylon line was collected, to be the worst affected area (YOC, 1979). A more intensive survey by Bell et al. (1985) estimated an accumulation of 15 163 m of nylon line at Llanishen Reservoir and 100000 shot at Woodstock Pool. However, these estimates by Bell et al. (1985) suffer from sampling problems. At Llanishen Reservoir the estimate for nylon line was calculated from only three replicate samples and consequently the confidence limits were very large and put serious doubts on the value of the results. At Woodstock Pool the estimated number of shot for the whole lake was determined from a limited sampling programme with all samples taken from within 1 m of fishing pegs. This survey largely overcame these problems through the use of stratified random sampling with 10 sample points in each stratum.
The Nature Conservancy Council (NCC) estimated an average accumulation of 6.6 pieces of shot per metre of bank per year for all lowland rivers and canals (NCC, 1981). This figure suggests that the estimated quantity of shot at Llandrindod Wells Lake would have accumulated in less than 6 years. The fishery at Llandrindod Wells Lake has, in fact, been in existence since the early 1950s and it is thought to have been heavily fished throughout its history. However, sampling in this survey was restricted to the surface (to a depth of 20 mm) of the Lake bank and a more extensive sampling programme incorporating deeper layers of the bank and areas below the Lake waterline could have perceivably increased the estimates (Mudge, 1984).
The vast majority of the shot and line at the Lake was shown to be discarded in close proximity to the fishing points. Such results were largely expected as much of the shot and line would be discarded both
32 lrven J. Forbes
accidentally and deliberately whilst anglers were preparing or 'packing up' their tackle. It therefore follows that lead shot numbers should be significantly higher on the wooden platforms than around the platforms. Also, the abundance of short lengths of line probably arose during tackle manipulations and relates to 'end snipping', that is, cutting off excess line after hook tying, etc. Nylon line pieces 5-10 cm in length were the most abundant at the Lake. This was also the most common length range found at Woodstock Pool (Bell et al., 1985). It is possible that much of the shot attached to short nylon lengths was discarded by deliberate 'end snipping'.
Shot and line in the environment cause most concern when 'available' to wildlife. At Llandrindod Wells Lake it is unrealistic to assume that the total estimated quantity of litter is available to wildlife. The compact nature of the bank substrate, especially around fishing points, would largely restrict sub-surface feeding of, for example, the resident mallard Anasplatyrhynchos and, in addition, much of the Lake bank is submerged below the waterline during the winter months. It is probable that shot and line on the actual wooden platforms represents the greatest hazard to the resident ducks, which often use these platforms as roost sites, especially those on the island. The regular removal of shot and line from all wooden platforms would be a simple but sensible precaution at the Lake.
In contrast to shot and line, the main problem created by general litter at the Lake was thought to be its 'visual disruption' of the environment. Large quantities of visually evident litter associated with angling would be expected to damage the reputation of the sport in the eyes of visitors, particularly non-anglers. The use of litter surface area to assess 'visual disruption' of the environment was a simplified approach to the problem as the perception of litter is influenced by many other factors besides size, such as litter colour, shape, and the degree of concealment by natural cover. However, the data on size, for different litter types, were sufficient to organise the site categories into groups with similar litter problems.
Roadways and mown grass areas (Group A) showed a low density of small litter pieces and hence a low visual impact. General visitors (e.g., walkers) exert the greatest pressure on these and would not be expected to bring a considerable amount of litter to the Lake. Large pieces discarded in this area would also tend to be collected by the County Council Refuse Collection Service which operates on a daily
Litter discarded by fishing lake 33
basis at the Lake. Category 4, areas of roadway directly adjacent to fishing points with some pressure, were also covered by regular litter collections. This category, where anglers were found to have discarded shot and line, showed a far greater abundance of small litter items than the categories in Group A, and consequently it can be concluded that much of this litter was probably discarded by anglers. Also, according to general litter characteristics, category 4 was grouped with category 7, the litter of which was exclusively dropped by anglers.
Group D, the areas from which anglers actually fished (categories 1, 2 and 3), contained the largest pieces and the highest densities of general litter items as well as the greatest variety of litter. This created a large visual impact, and must in part have arisen as a consequence of the long periods that anglers spend at the Lake. Most anglers remain for several hours, whilst some come for several days: this is in marked contrast to the typical general visitor. Up to 25% of the litter items discarded by anglers were also thought to have arisen as a direct consequence of the sport, for example, plastic bread bags and a variety of tin cans which had originally contained items commonly used as fishing bait.
Categories 1 and 7 on the island were shown to contain greater quantities of litter than their equivalent categories (2 and 8) on the Lake edge. These problems on the island probably relate to several factors, the most obvious being the absence of facilities for the disposal and clearance of litter. However, the secluded nature of the island may have encouraged anglers to be less careful when disposing of litter of all types. This situation is probably aggravated by both the frequent fishing matches and night fishing expeditions that only occur on the island.
Although the Lake edge does not have the same problem with general litter as the island, its clearance should be treated as a priority because it is far more evident to visitors. Steps should also be taken to reduce the quantities of all litter types being discarded around the Lake in the future. The placement of litter bins close to fishing points and the 'posting' of appropriate notices could result in a substantial reduction of litter at the Lake.
ACKNOWLEDGEMENTS
I would like to thank Professor R. W. Edwards and Mr T. C. lies for their constructive criticism during the draft stages of this paper. I am
34 Irven J. Forbes
also grateful to Dr F. M. Slater for his assistance at Llysdinam Field Centre. This study was jointly sponsored by UWIST and the Manpower Services Commission.
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Birkhead, M. (1981). How the fishermen kill the swans. New Scient., 9tl, 14- 15.
Birkhead, M. (1982). One that hasn't got away. The Guardian, December 23. Cooke, A. S. (1976). The effect of fishing on waterfowl at Grafham Water.
Report to Cambridge Bird Club, 48, 40-46. Gauch, H. G. Jr (1982). Multivariate analysis in community ecology. Cambridge,
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conservation in the River Teme catchment. J. appl. Ecol., 15, 373-84. Mudge, G. P. (1984). Densities and settlement rates of spent shotgun pellets in
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Conservancy Council Report. Simpson, V. R., Hunt, A. E. & French, M. C. (1979). Chronic lead poisoning
in a herd of mute swans. Environ. Pollut. Ser. A, 18, 187-202. Thomas, G. J. (1980). Review of ingested lead poisoning in waterfowl. In
International Waterfowl Research Bureau Bulletin, 46, 43-6. Young Ornithologist Club (1979). Waterside menace. Sandy, Young Ornitholo-
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