At each sampling station, bottom trawls were performed with a conical net measuring 34 m at the upper headrope
. The effective trawling time varied between 5 and 24 min, with an average of 17.5 min, and a total of 41 (2006) and 45 (2007) trawls were carried out.
The nylon net has a 25.5-m headrope
and 34.1m footrope which is 5.2 cm in diameter and constructed of wire rope with a single wrap of both polypropylene line and split rubber hose, but without bobbins or rollers to allow it to better conform to the smooth bottom in the EBS.
Tenders are invited for 210/2/3 14 mm mesh, Complete fitting with headrope
and foot rope 8mm sinker, Float, Angla etc.
Those nets that were not available for inspection were characterized according to their length (headrope
and footrope) and mesh size in the body and the cod end.
At first, the Cartagena fleet used one trawl on each side, made out of polyamide and with headrope
lengths (HRL) between 65- to 90-feet.
length for the primary trawls was similar among areas and target with an average from 50.5 ft to 52.5 ft.
Otter trawls were 5.7 m wide at the headrope
with 38-mm stretched nylon multifilament mesh.
Following the 1997-1998 El Nino, three specimens of a small labrid were collected in the Southern California Bight (SCB) by 7.6-m wide (headrope
) semiballoon otter trawls with 1.2-cm cod-end mesh.
This analysis identified a fixed set of 105 core stations and sampling was reduced to May and June only, except for July when weakfish were sampled (dropped in 1998; sampling in July was reinitiated in 2004 for spotted seat-rout), and only a trawl with a 3.2-m (10.5-ft) headrope
and with 6.4-mm (0.25-in) bar mesh would be used.
Tenders are invited for 210/3/3 28 mm mesh, Complete fitting with headrope
8mm and foot rope 10mm sinker, Float, Angla etc.size 500ft.
The vertical opening and its distance in relation to the bottom was controled by the Ossian Trawl-Eye 49 KHz transducer fixed in the headrope
. These systems allowed maintaining the net operating at specific depths during fishing and further classify the stations into different depth strata.
On both occasions, the research vessel Naturaliste was configured to operate as a twin-gear-rigged otter trawl system (19.8 m headrope
nets), using the standard 50-mm diamond mesh codend used by commercial prawn fishers.