Bullimore et al.: Study of catches in a fleet of "ghost-fishing" pots 
251 
Table 2 
Newly captured animals for the entire fleet of pots at various time intervals after first deployment of gear. For ethical reasons, after 
day 88, the number of pots was reduced to 9 and after day 270 the number of pots was further reduced to 6. Mean catch per pot per 
year was calculated from the sum of the total new catch divided by the number of pots fishing at each time interval. 
Days from original deployment 
1 4 12 27 40 69 88 101 125 270 333 369 
Number of pots fishing 
Mean catch 
Species 
Common name 
12 
12 
12 
12 
12 
12 
12 
9 
9 
9 
6 
6 
per pot per year 
Maja squinado 
spider crab 
15 
3 
9 
10 
6 
7 
3 
2 
0 
1 
8 
6 
7.08 
Cancel' pagurus 
brown crab 
3 
5 
5 
3 
3 
9 
4 
0 
3 
8 
7 
6 
6.06' 
Necora puber 
velvet swimming crab 
1 
0 
1 
0 
0 
0 
0 
2 
2 
0 
0 
0 
0.61 
Homarus gammarus 
lobster 
2 
1 
1 
0 
0 
0 
0 
0 
1 
0 
0 
0 
0.44' 
Labrus bergylta 
ballan wrasse 
0 
0 
0 
1 
0 
0 
2 
0 
1 
1 
4 
5 
1.97 
Bctllistes carolinensis 
triggerfish 
0 
0 
0 
0 
0 
0 
1 
0 
0 
0 
0 
0 
0.08 
Scyliorhinus canicula 
lesser-spotted dogfish 
0 
0 
0 
0 
0 
0 
1 
0 
0 
0 
0 
0 
0.08 
1 indicates those animals 
for which all observed catches died. 
that may have entered the pots and died without being ob- 
served by the divers. 
Discusssion 
The results of this experiment demonstrate that lost pots 
can continue to fish for many months after the bait within 
them has been consumed. There was no sign of deterio- 
ration in the integrity of the pots throughout the study. 
Several “ghost-fishing” pots were found in close proximity 
to the experimental fleet. This discovery emphasized the 
practicality of our study and confirmed that location of our 
experiment was representative of sites used by pot fisher- 
men and that pot losses do occur in this area. 
Spider and brown crabs dominated the catches, whereas 
lobster, velvet swimming crab, and fishes were caught less 
frequently. The rate of decline of the CPUEs for spider and 
brown crabs both followed similar patterns. We extrapolated 
the CPUE for only the first 125 days of the experiment be- 
cause our own observations indicated that spider crabs mi- 
grate into shallower waters around Skomer to breed in the 
late spring and early summer. Consequently, catches of spi- 
der crab were high in August and tailed off as the experi- 
ment extended into autumn and winter and the spider crabs 
migrated farther offshore. In contrast, brown crabs are resi- 
dent throughout the year in the Skomer MNR and although 
the CPUE was low during the winter period, it is possible 
that they continued to be caught sporadically between days 
125 and 270. A second pulse of spider crab and brown crab 
catches occurred 333 days after initial deployment of the 
pots, which may be linked to rising water temperatures that 
occur in late spring and early summer (Fig. 2). 
We were able to confirm mortality only for lobster and 
brown crabs (0.44 lobster and 6.06 brown crab per pot per 
1.25 
04 
0 35 
0.3 
0.25 
^ 0 100 200 300 400 500 
LL 
o 
0 100 200 300 400 500 
Days after gear deployment 
Figure 2 
The catch per unit of effort (CPUE) for (A) spider 
crabs and (B) brown crabs on each of the sampling 
dates (open circles). The closed circles represent the 
predicted values for CPUE as determined from the 
regression relationships (see text). 
A 
