5. Results of fishing experiments

Some of the results of the fishing experiments are commented on below. One should note, however, that in a programme for "swept area" biomass estimation, the trawl stations are positioned more or less randomly and with no intention of obtaining high catch rates. The catch rates thus do not simulate those of a commercial fishery and they are presented here merely to give a rough impression of the general occurrence and abundance of bottom fish on the shelf.

The bottom trawl used is a shrimp-cum-fish trawl (see Annex 1) and it may not be as efficient for shrimp as specially designed shrimp-trawls.

Colombia

Annex 2 gives a record of all fishing stations. In the 25 bottom hauls made, the catch rates are distributed by catch size groups as follows:

Catch group (tons/hour):	0-.03	.03-.1	.1-.3	.3-1	1-3	>3
No of catches	5	6	8	5	0	1

The majority of the catch rates thus lie in the range 100 kg to 1 ton. The mean catch rate was 513 kg/hr. Carangids, mainly bumper were caught in 14 of the hauls with a mean rate of abt 300kg/hr, clupeids at 10 stations with a mean rate of 27 kg/hour, and sharks were found in 8 hauls with a mean of 28 kg/hr. The largest catch, 8.2 tons/hr consisted of anchovy.

Panama

The records of all the fishing stations made are shown in Annex 2.

The Panama Gulf.

The 27 hauls made with bottom trawl gave catch rates pr hour distributed as follows:

Catch group (tons/hour):	0-.03	.03-.1	.1-.3	.3-1	1-3	>3
No of catches	9	5	5	10	1	1

The mean of these was 435 kg/hr, less than 30% of the rate obtained during the previous survey. Carangids constituted 58% of the total catch, while the share of clupeids and anchovies were 6 and 9% respectively. Among the demersal species butterfish Peprilus are the dominating, followed by various grunts Pomadasyidae.

The shelf squid, Loliolopsis which were caught in substantial quantities during the first two surveys, were present in 16 of the catches in the recent survey, but never exceeding a rate of 10 kg/hour. Also for the Layang scad Decapterus macrosoma which were previously reported in good quantities in central parts of the Gulf, the catches were poor. The scad was present in 8 hauls, but only one haul exceeded a 50 kg/hour limit, and gave a catch of 560 kg/hour.

Western coast.

The 19 bottom trawl catches in this area gave catch rates as follows:

Catch group (tons/hour):	0-.03	.03-.1	.1-.3	.3-1	1-3	>3
No of catches:	4	6	6	3

The mean catch rate was abt 145 kg/hr., about 50% of the rate obtained during the previous survey. Most part of the catch in the bottom trawl was small pelagic fish and small demersals with lesser commercial value. As during the two previous surveys good sized snapper were taken at 40-50 m east of Pta Mariato.

Costa Rica

Annex 4 presents a record of the fishing stations. The catch rates of 39 successful bottom trawl hauls were distributed as follows:

Catch group (tons/hour):	0-.03	.03-.1	.1-.3	.3-1	1-3	>3
No of catches:	3	8	12	13	3	0

Catch rates between 100 kgs and 1 ton were thus most common. The mean rate was 330 kgs/hr. The main groups in the catch from Costa Rica were, with their roughly share of the total catch:

Carangids	13 %	Groupers	3 %
Clupeids	2 %	Snappers	7 %
Anchovies	6 %	Croakers	10 %
Argentina	12 %	Shrimp	5 %
Peprilus	4 %	Squid	2 %