5. Results of fishing experiments

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 during this part of the cruise are shown in Annex 2, those numbered from 87 through 121 refer to the area off Nicaragua (cfr. Figure 1).

Most of the trawl stations in the inshore area represent prelocated hauls for faunistic studies and swept area estimates. The catch rates were low in this area from 1 to 880 kgs/hr, but with one catch made on an acoustic recording of abt 2.2 tons/hr.(Station no 119). The results from the fishing experiments thus confirm the general impression from the acoustic survey of scattered fish.

Fishing offshore was primarily arranged to cover different depths between abt 180 and abt 350 m in testing for langostino and shrimp, but a number of hauls were made on recordings of fish in the depth range 160 - 200 m. The fish catches made, standardized to rates per hour's tow are shown in Table 1. The large catch of threadfin bass at station 88 could not be repeated further west, but as can be seen from the table a number of good catches of silver smelt and cutlassfish were made over a substantial area. These results as well as those from the acoustic survey indicate that there may be a considerable biomass of these fish along the edge of the slope. More detailed fishing trials and further acoustic survey work should be made on these resources.

Table 1. Fish catches, offshore community, Nicaragua region. Standardized to rates of catch per hour's tow, tons.

Station no	Depth m	Silver smelt	Cutlass fish	Threadfin bass	Others	Total
87	180		3.0			3.0
88	170	4.2		15.1		19.3
92	175		0.2			0.2
93	190	0.9		0.3	2.6	3.8
99	160	1.1				1.1
101	170		80.0			80.0
102	200	0.9				0.9
115	200	0.2	0.8			1.0

Notes: Catch of st 101 was 20 tons in 15 minutes tow St 92 pelagic haul for identification.

Table 2. Catches of langostino and shrimp, offshore, Nicaragua region.

Station no	Depth m	Langostino tons/hour	Shrimp kgs/hr
101	170
102	200
103	275	0.18	65
104	350	0.03	107
105	250	2.6
106	300	1.0
113	180	6.6
114	180	3.1
115	200	0.1
116	250	0.1	20
118	130	0.9

The results of these scattered fishing stations do not form the basis for an estimate of the potential of this resource. They confirm, however that it must be considerable. A more detailed coverage could be included in the programme of the next cruise.

Only a limited effort was spent on the testing of the availability of oceanic squid, see Table 3. Two cases of some availability was found with catches of abt 14 and 11 kgs on two hand jigs in 15-20 minutes. Unfavourable weather may have affected part of this effort. A more oceanic coverage should have been made, but time did not allow this.

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

Date	Hour	Latit.	Longi.	Depth	Observations	Catch
		° '	° '			N	W (kgs)
22/2	0540	11 22	87 04	320m	Negative	0
22/2	1900	11 40	87 20	247m	Small specim.	0
22/2	2130	11 43	87 31	580m	Small specim.	5	2.0
22/2	2300	11 43	87 40	>500m	Medium specim.	20	10.5
24/2	0240	11 52	87 53	>500m	2 specim.	1
24/2	0350	11 52	88 01	>500m	Negative	0
24/2	0530	12 03	88 01	>500m	Negative	0
26/2	0015	12 20	88 18	>500m	Medium specim.	20	14.2
26/2	0110	12 13	88 22	>500m	Negative	0
26/2	0330	12 23	88 28	>500m	Few	2	1.2

El Salvador

The fishing stations worked on the shelf off El Salvador are recorded in Annex 2, stations 128 through 161. Catch rates in the arbitrarily located hauls inshore were generally low, ranging from abt 20 to abt 900 kgs per hour's tow. One should recall, however, that most of the fish observed acoustically here are pelagic schooling fish which are not very vulnerable to a bottom trawl. Commercial bottom fish such as snappers were scarce. Sharks occured in numbers in some of the hauls.

Offshore only a few of the hauls gave substantial catch rates of fish. The highest catches were 1 ton/hr of cutlassfish (Station no 129), and 3.7 and 0.7 for silver smelt (stations 137 and 140). The catch rates obtained for langostino and shrimp are shown in Table 4. There are as can be seen a number of hauls with catch rates of langostino of around 1 ton per hour and these are spread over a very wide area (cfr. Figure 1). One should note that no attempts were made to make repeated hauls in areas of high catch rates. The effort was used to try to describe the distribution by depth and area of the resource. The catches generally contained a mixture of small and larger langostino. In very shallow water only small specimens occured, but only one catch was made with fairly large sized langostino only (st.155). The size composition may undergo seasonal changes.

Table 4. Catches of langostino and shrimp, offshore, El Salvador region.

Station no	Depth m	Langostino tons/hour	Shrimp kgs/hr
128	180
129	250		107 juv.
130	80		90 juv.
135	130	0.2	46 juv.
136	15o	0.05
137	180
138	250	0.2
139	115	0.3
140	180	1.2
141	250	1.0	12
148	200	0.7
149	300	0.1	3
150	250	1.2	10
151	160	0.2
155	200	0.3
156	250	0.4	3
157	180	1.2

Table 5 gives a record of the results of the squid testing.

Table 5. Testing for oceanic squid (Dosidiscus gigas) with light and jigging, El Salvador.

Date	Hour	Latit.	Longi.	Depth	Observations	Catch
		° '	° '			N	W (kgs)
27/2	0410	12 29	88 53	>500m	Negative	0
27/2	0455	12 19	88 51	>500m	Small specim.	0
28/2	0005	12 48	89 28	250m	Medium spec.	0
28/2	0053	12 41	89 29	>500m	Many	12	4.0
28/2	0155	12 35	89 31	>500m	Many	15	5.7
28/2	0310	12 40	89 22	>500m	Many	52	15.0
28/2	0425	12 45	89 15	>500m	Negative	0
1/3	0200	12 47	89 57	>500m	Some	2	0.25
1/3	0400	12 39	90 08	>500m	A few	3	0.7
2/3	0210	13 00	90 10	400m	A few small	0
2/3	0320	12 53	90 17	>500m	Many specim.	16	6.5
2/3	0445	13 03	90 17	480m	Negative	0

Squid was found to be present over a wide area, but, catches were generally low. This could be related to the small size of the squid and its low catchability for jigging.