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 24 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	1	6	9	7		1

The majority of the catch rates thus lie in the range 100 kg to 1 ton. The mean catch rate was 428 kg/hr. Carangids, mainly bumper was caught in 17 of the hauls with a mean rate of abt 140 kg/hr while sharks were found in 15 hauls with a mean of 23 kg/hr. The largest catch, 3.6 tons/hr consisted of cutlassfish.

Panama

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

The Panama Gulf.

The 31 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	1	2	7	9	6	6

The mean of these was 1 580 kg/hr, while 7 hauls with pelagic trawl showed a mean catch rate of 755 kg/hr. Carangids was the most common fish family, occuring in more than 80% of the catches with a mean catch rate of 860 kg/hour. Two species dominate among the Carangids, Pacific bumper in shallow water and Layang scad at depths of more than abt 80 m. Round herring was caught in some quantities together with scad in deeper waters. Spanish mackerels, barracudas and sharks occured in 8 - 14 catches with mean rates of abt 20 - 30 kg/hr. In water depths of 60 m and more butterfish catch rates ranged up to abt 750 kg/hr. Thread herring and various anchovies were identified by many catches in their areas of distribution, but the anchoveta, Cetengraulis mysticetus only occurred on station, 523, and in insignificant quantities.

In the two previous surveys shelf squids, Loliolopsis were caught in substantial quantities in parts of the Gulf. At this time they appeared to be almost completely absent with only insignificants amounts in a small number of catches. One haul at 300 m off the shelf gave a catch of nearly 5 tons of cabezon shrimp. A large catch was obtained in this position also in Survey II. Six squid jigging stations were worked off the shelf, but only a few small specimens were caught. On four of the stations many small squid were observed in the light.

Western coast.

The 32 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:	1	4	18	7	2

The mean catch rate was abt 300 kg/hr., thus considerably lower than in the Gulf of Panama. Carangids occurred in 2/3 of the hauls, but with only low catch rates. Sharks occurred in abt. half the hauls with a mean catch rate of 52 kg/hr and barracudas in 1/3 with a mean rate of 90 kg/hr. Small quantities of Penaeid shallow water shrimp occured in the catches over a wide area and also the crystal shrimp (P. brevirostris) was found to have a wider distribution than during the May survey. A few catches of good sized snapper were taken at 40 - 50 m east of Pta. Mariato where similar catches were made in May. Lobster was caught in small quantities in some shallow hauls close to the shore.

Costa Rica

Annex 4 presents a record of the fishing stations. The catch rates of the 38 successfull 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:	2	7	10	14	3	2

Catch rates between 100 kgs and 1 ton were thus most common. The mean rate was 990 kgs/hr, but if one large catch (20 t/hr of sea bass) is excluded the mean rate is somewhat less than 0.5 t/hr. Snappers formed an important element in the catches in Costa Rican waters occurring in abt 3/4 of all hauls with a mean catch rate exceeding 200 kgs/hr. Good catches were obtained in Bahia de Coronado, off Pta Judas, to the west of Cabo Blanco and south of Cabo Velas. Groupers occurred in about half of the hauls, but with a mean rate of only 40 kgs/hr. Carangids was found in small amounts in nearly all hauls, barracudas in 23 hauls with a mean rate of 35 kgs/hr. Sharks were far less common than in Panama, being found in only 7 hauls. Shrimps occurred widely, but in small amounts. This was also the case with the dart squid, Loliolopsis. Light and jigging for giant squid was tried in a number of locations off the slope. The results were largely negative, only small sized squid was observed in a few places.