Stiansen et al.: Efficiency and catch dynamics of square and conical crab pots 
41 
Aluminium frame 
Float (12 mm diameter) 
(12 mm diameter) 
Seen from one end 
Seen from the side 
Figure 1 
Drawing of the square pot design used to capture red king crab (Paralithodes camtschaticus). 
The frame is lined with 3-mm braided polyethylene netting with a mesh size of 100 mm. The 
20-cm long bait bag is made of polyamide netting and has a mesh size of 22 mm. The pot 
weighs 37 kg out of water. All pot dimensions are in mm. 
Figure 2 
Drawing of the conical pot design used to capture red king crab ( Paralithodes 
camtschaticus). The frames are made of 20-mm steel bars and lined with 
4-mm polyethylene diamond netting with a mesh size of 150 mm. The 20-cm 
long bait bag is made of polyamide netting with mesh size of 22 mm. The 
pot weighs 17 kg in air. All pot dimensions are in mm. 
information is crucial for both im- 
proved population estimates and re- 
source-friendly harvesting practices. 
Materials and methods 
The square pot (Fig. 1) had two 
funnel-shaped entrances with 
outer openings of 150x120 cm. The 
entrance area thus made up half of 
the pot’s horizontal circumference. 
The netting used to line the frames 
had a mesh size of 100 mm. The 20- 
cm long bait bag was made of small- 
mesh netting (22 mm mesh size) and 
was placed in the center of the pot 
between the entrance openings. The 
weight of the pot out of water was 
37 kg. The funnel of the conical pot 
(Fig. 2) was made of hard plastic, 
had an outer diameter of 45 cm, and was located at the 
top of the pot. The mesh size of the netting liner was 
150 mm. A bait bag similar to that used in the square 
pots was located at the center of the pot, 10 cm below 
the inner funnel opening. The weight of the pot out of 
water was 17 kg. 
The fishing trials were carried out between 19 Octo- 
ber and 6 November 1998 in the Varangerfjord (close to 
the Russo-Norwegian border) (Fig. 3), which is the area 
with the highest density of RKC in Norwegian waters. 
Four commercial coastal fishing vessels of 10-12 m 
length were chartered for the experiment. The pots 
were set at depths of 50-250 m on silty and muddy 
bottom substrates. 
Each vessel fished with 24 pots, arranged in six 
strings — each string consisting of two square and two 
conical pots (Fig. 4). The two types of pots were at- 
tached alternately to a 12-mm diameter rope at inter- 
vals of about 30 m, a between-pot distance commonly 
used by commercial fishermen. Each pot was baited 
with about 1 kg of chopped (~2 cm pieces), thawed At- 
lantic herring ( Clupes harengus). 
The analyses were based on the 112 string settings 
where there was catch in at least one of the four pots. 
