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.

Nicaragua.

The records of all the fishing stations made are shown in Annex 2. All bottom trawl stations in the inshore area at depths less than abt 60 m represent prelocated hauls for faunistic studies and swept area estimates.

The 41 bottom trawl hauls in Nicaragua and Golfo de Fonseca 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	3	5	9	15	5	4

By bottom depth strata the mean catch and the number of hauls are distributed as follows:

	0-29m	30-59m	60-99m	100-149m	150-200m	>200m
Mean catch (kg/h):	400	380	280	390	810	4000
Number of hauls:	9	7	8	5	3	9

The mean of the zone from 0 to 60 m is 390 kg/hour, a 25 % drop in catch rate since survey number III (514 kg/hr), but in close agreement with survey no II (430 kg/hour).

The catches of the inshore stations standardized to rates per hour towed (in kilos) and grouped as pelagic fish, bottom fish and shrimps plus lobsters are shown in Table 1. The dominating pelagic species are anchovies, thread herring, carangids, mackerel and barracudas.

Table 1. Fish catches, inshore community, Nicaragua. Catch rates in kg. per hour towed.

St. no.	Depth m	Pelagic fish	Bottom fish	Shrimps Lobster	Total
962	62	190	110	2	300
967	51		380	35	410
968	32	215	275	50	320
969	81		195	5	200
971	62		45		45
972	48	210	750		960
973	23	300	440	5	745
978	26	210	465	10	690
979	32	145	150	1	295
980	26	80	150	5	235
981	64		980	50	1030
986	37	5	70	5	80
987	17	115	230	1	245
988	53		40		40
990	22	45	10		55
991	20	20			20
992	10	45	610	145	800
993	18	85	25	2	210
994	24	45	575	15	635
996	32	45	250	20	315

Fishing offshore was primarily arranged to cover different depths between 100 and 400 m in testing for langostino and shrimp, and 19 hauls were made in this zone. Of these 11 gave catches exceeding 500 kg/hour and these are shown in Table 2 as rates per hour. The highest catches of langostino were obtained between 200 and 280 m bottom depth. This is in contrast the previous survey when the highest catches were obtained between 110 and 140 m depth. To see if the difference indicates sasonal depthwise migration or just reflects distributions in separate locations, a more thorough analysis is necessary. The catches of the deep sea shrimp, "cabezon" are remarkable low compared to the previous surveys. None of the hauls exceeded 70 kg/hour.

Table 2. Bottom trawl stations with relatively large catches, offshore community, Nicaragua region. Standardized to rates of catch per hour's tow, tons.

Station no	Depth m	Fishes	Langostino	Shrimps	Total
951	200	0.2	0.5	0.016	0.8
953	153	2.0			2.0
956	269	0.4	5.6		6.0
957	219	0.2	2.8	0.017	3.0
958	281		14.0	0.040	14.0
959	255	10.5	1.0		11.6
961	203		4.0		4.0
963	101	0.5		0.008	0.5
976	263	0.7	4.2	0.014	5.0
983	118	0.2	0.6		0.8
984	265	0. 1	1.9	0.006	2.0

A limited effort was spent on testing the availability of oceanic squid with light and jigging, see Table 3. Squid were caught at three of five stations. The big specimens located at about 100m depth during the previous survey was not caught in the last.

Table 3. Testing for oceanic squid (Dosidiscus gigas) with light and jigging, Nicaragua.

Date	Hour	Latit.		Longi.		Depth	Observations	Catch
		°	'	°	'			N	W (kgs)
18/11	23	11	13	87	04	>500m	Medium	1	1.5
19/11	00	11	14	87	01	500m	Negative	0
22/11	00	12	17	88	09	>500m	Medium	1	0.3
23/11	01	12	20	88	07	127	Negative	0
23/11	03	12	10	88	16	>500m	Medium	19	6.8

El Salvador

The 34 bottom trawl hauls in El Salvador 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	6	5	10	7	6

By bottom depth strata the mean catch and the number of hauls are distributed as follows:

	0-29m	30-59m	60-99m	100-149m	150-200m	>200m
Mean catch (kg/h):	300	300	90	290	1680	1300
Number of hauls	12	11	3	1	3	3

The mean of the bottom trawl catches in the 0-60 bottom depth zone was 300 kg/hr which is in close agreement with the results obtained in Survey III (310 kg/hr).

The catches of these inshore stations standardized to rates per hour towed (in kilos) and grouped as pelagic fish, bottom fish and shrimps are shown in Table 5. The dominating pelagic species are barracudas, anchovies, thread herring and carangids.

Table 5. Fish catches, inshore community, El Salvador. Catch rates in kg per hour towed.

St. no.	Depth m	Pelagic fish	Bottom fish	Shrimps	Total
998	49		3		3
999	19	24	11		35
1000	18	93	39	130	262
1001	24	142	165	12	319
1003	98		138		138
1004	63		19	1	20
1005	39	110	36		146
1006	16	5	68	6	79
1007	38	31	34	1	66
1008	20	3	27		30
1009	20		4		4
1010	35	180	225	2	407
1011	25	926	187		1123
1012	19	71	44	19	134
1015	57		81	1	82
1016	24	505	46	2	553
1017	32	577	112	51	740
1018	39	144	111	2	257
1019	28	139	260	162	561
1020	32	667	472	4	1143
1021	39	16	185	1	202
1023	25	82	6		88
1024	37	22	105		127
1025	28	177	192	11	380
1026	32	22	110	88	220
1027	73	1	101	24	126

Fishing offshore was arranged to cover different depths between 100 and 300 m in testing for langostino and shrimp. Seven stations were carried out and these are shown in Table 6 as rates per hour. Deep sea shrimp were as previously only found in small quantities, but mantis shrimp is very common and abundant in this area especially in deep water. Whether this species may have any future commercial value is uncertain. As can be seen from the table catch rates are generally high for both langostino and mantis shrimp. The few high catches of fish obtained in offshore waters consisted mainly of silver smelt Argentina.

Table 6. Bottom trawl stations with relatively large catches, offshore community, El Salvador shelf. Standardized to rates of catch per hour's tow, tons.

Station no	Depth m	Fishes	Langostino	Squilla	Total
997	104	0.3			0.3
1002	159	0.3	0.1	0.8	1.2
1014	248	0.1	2.0	0.9	3.0
1028	240		0.5	0.3	0.8
1029	315				0.0
1030	195		2.1	0.3	2.4
1031	175	0.2	1.1	0.2	1.5

A limited effort was spend in testing the availability of oceanic squids by light and jigging. Six stations were worked off the shelf mostly beyond 500m of depth. One medium sized specimens were caught each at two stations in the southern part of the shelf. Small sized squid were observed in the surface waters on several stations. They did however not take the hook.