5. Fishing experiments

A record of all fishing stations is given in Annex II. The design of the bottom trawl is shown in Annex I.

A significant part of the survey effort on the north coast was spent surveying the offshore area for trawlable bottom and only 5 successful hauls were made. Table 1 shows standardized catch rates by main groups for the trawl stations made. “Pelagic” comprises Clupeidae (sardines), Engraulidae (anchovies), Carangidae, Scombridae, Sphyraenidae (barracuda) and Trichiuridae (hair-tails). “Demersal” includes the families Sciaenidae (croakers), Lutjanidae (snappers), Pomadasiydae (grunts), Serranidae (groupers), and Ariidae (catfish). The catch rates on the north coast are generally high, and taken into account the general hydrological conditions this is considered as an abundant area of fish. Table 2 and 3 shows the catch rates by families for pelagic and demersal fish, demonstrating the composition of the catches. The pelagics are dominated by Carangids, the bottom fishes by croakers. No anchovies are present.

Table 1. TRINIDAD NORTH COAST. Catch rates for main groups in bottom trawl stations standardized to kg/hour.

ST. NO.	DEP.	Pelagic	Demersal	Shark	Squid	Shrimp	Other
408	90	597.00	714.00	207.00	3.00		269.60
409	86	828.36	404.36	134.36	14.00		190.19
410	90	17.00	540.00	217.00		12.40	117.40
414	83	11.40	85.90		3.20		3.70
415	43	1006.70	61.50	26.60	10.60		41.60
MEAN		492.09	361.15	116.99	6.16	2.48	124.50

Table 2. TRINIDAD NORTH COAST. Catch rates by families for pelagic fish in bottom trawl hauls, kg/hour.

ST. NO.	DEP.	Sardins	Barracuda	Carangids	Scombrids	Hairtails	Other
408	90		3.00	450.00		144.00	1193.60
409	86	3.45	8.73	798.00	4.18	14.00	742.91
410	90		7.70			9.30	886.80
414	83	2.20	3.00	6.20			92.80
415	43	574.80	97.00	268.50	45.00	21.40	140.30
MEAN		116.09	23.89	304.54	9.84	37.74	611.28

Table 3. TRINIDAD NORTH COAST. Catch rates by families for demersal fish, kg/hour.

ST. NO.	DEP.	Croakers	Snappers	Grunts	Groupers	Catfish	Other
408	90	697.60	9.00	1.40	6.00		1076.60
409	86	364.72	30.91		8.73		1166.91
410	90	457.90	77.50		4.60		363.80
414	83		85.80		0.10		18.30
415	43	8.60	52.90				1085.50
MEAN		305.76	51.22	0.28	3.89		742.22

Table 4 presents the catch rates for deep water shrimp on the slope off the east coast. Between 388 m and 733 m depth the rates ranged from 10.3-12.8 kg/hour, the 2 largest catches being obtained at the deepest station. The large and deep red Plesiopenaeus edwarsianus constituted about half the shrimp catch.

Table 4. SLOPE OFF TRINIDAD EAST COAST. Catch rates for main groups in bottom trawl stations standardized to kg/hour.

ST. NO.	DEP.	Pelagic	Demersal	Shark	Squid	Shrimp	Other
416	192	2.20	39.80		0.40	2.60	31.70
417	388	0.40		5.40	3.00	11.60	78.00
418	603				2.62	11.55	57.94
419	585		3.00		0.80	10.30	45.40
420	712	1.80			0.60	13.30	35.00
421	733	1.47			8.33	12.80	24.93
422	400					10.00	28.00
MEAN		0.84	6.11	0.77	2.25	10.31	43.00

Table 5 shows the standardized catch rates for the broad groups in shallow water off the east coast south of the Manzanilla Bank. These are all prepositioned bottom hauls. St.no.423 thru 427 were worked during day, St.no.429 thru 432 during night. The rates are substantially lower than on the north coast for both pelagic and demersal species with a mean rate of 20 kg/hour and 87 kg/hour respectively compared to 492 kg/hour and 361 kg/hour in the north. Table 6 and 7 shows the catch rates for the different families by main groups. The family composition varies by hauls but croakers and snappers constitute most of the demersal species. Pelagics are scarce and anchovies are lacking in the bottom trawl samples although they are present in the area as shown by the pelagic haul at St.no.428.

Table 5. TRINIDAD EAST COAST. Catch rates for main groups in bottom trawl stations standardized to kg/hour.

ST. NO.	DEP.	Pelagic	Demersal	Shark	Squid	Shrimp	Other
423	56	15.60	5.70	4.00	5.40	0.80	17.10
424	52	29.60	7.10	1.60	3.90		6.00
425	39	50.60	33.60	12.00	2.00		8.80
426	37	4.00	303.00				65.60
427	47	43.00	255.00	48.00		14.60	39.80
429	56	14.40	123.20	1.60		11.10	78.00
430	70	6.60	55.20	1.20		4.00	48.40
431	61		4.60	1.60			9.40
432	60	17.40	3.20			0.50	3.40
MEAN		20.13	87.84	7.78	1.26	3.44	30.72

Table 6. TRINIDAD EAST COAST. Catch rates by families for pelagic fish in bottom trawl hauls, kg/hour.

ST. NO.	DEP.	Sardins	Barracuda	Carangids	Scombrids	Hairtails	Other
423	56	0.30		0.50	14.80		33.00
424	52		6.00	11.60	12.00		18.60
425	39	2.80	20.00	18.60	9.20		56.40
426	37		4.00				368.60
427	47	26.20	4.80	0.60		11.40	357.40
429	56	7.20		1.60		5.60	213.90
430	70	0.20		5.60		0.80	108.80
431	61						15.60
432	60	14.40				3.00	7.10
MEAN		5.68	3.87	4.28	4.00	2.31	131.04

Table 7. TRINIDAD EAST COST. Catch rates by families for demersal fish, kg/hour.

ST. NO.	DEP.	Croakers	Snappers	Grunts	Groupers	Catfish	Other
423	56		5.10		0.60		42.90
424	52		7.10				41.10
425	39		32.80	0.80			73.40
426	37		261.40	41.60			69.60
427	47	234.20	6.00	2.40		12.40	145.40
429	56	110.40	2.80		1.20	8.80	105.10
430	70	50.80	2.40		2.00		60.20
431	61	4.60					11.00
432	60	3.20					21.30
MEAN		44.80	35.29	4.98	0.42	2.36	63.33

Results of the bottom trawl survey in the Joint Research Area appears from Tables 8 to 10. Table 8 lists the standardized catch rates by broad groups for all the prepositioned hauls made during day-hours. The catch rates are relatively high, especially for the pelagic in the north western pan of the area. The pelagic (Table 9) comprise a mixture of all the main family groups whereas the bottom fishes (Table 10) are dominated by croakers.

Table 8. JOINT RESEARCH AREA. Catch rates for main groups in bottom trawl stations standardized to kg/hour.

ST. NO.	DEP.	Pelagic	Demersal	Shark	Squid	Shrimp	Other
433	50	82.00	171.60	1.80		6.00	5.60
434	44	2454.40	184.80	41.00			46.40
435	30	1242.00	698.00	100.40			303.60
436	56	61.50	68.00		0.24	0.74	0.50
437	70	23.00	26.00			0.50	0.50
438	22	337.40	29.90	2.00		0.70	22.20
439	20	267.20	172.80	21.00		0.64	52.80
440	28	123.20	143.00	2.60	5.00	1.60	45.60
446	44	87.60	309.20	92.40		0.80	15.60
447	30	174.60	28.00	1.80		2.20	31.60
448	51	16.60	93.80	13.60		2.20	19.00
449	67		435.20			1.20
450	19	0.09	2.23		0.09	0.17	0.09
451	27	64.60	63.20		10.40	2.40	30.20
452	19	44.00	131.90	20.20	1.50	7.20	12.50
453	32	10.00	27.34		0.50	5.66	0.83
454	33	58.80	654.00			36.00	21.60
MEAN		296.88	190.53	17.46	1.04	4.00	35.80

Table 9. JOINT RESEARCH AREA. Catch rates by families for pelagic fish in bottom trawl hauls, kg/hour.

ST. NO.	DEP.	Sardines	Anchovies	Carangids	Scombrids	Hairtails	Other
433	50	56.40				25.60	185.00
434	44	1354.20	401.80	205.00	464.60	9.60	291.40
435	30	87.40	9.20	377.20		754.40	1115.80
436	56	21.00		0.50		40.00	69.48
437	70	2.00		6.00		15.00	27.00
438	22	60.20	14.00	1.40		261.80	54.80
439	20	55.20	8.00	7.20		196.80	247.24
440	28	3.60	1.00	2.00	96.60	20.00	197.80
446	44	16.20				71.40	418.00
447	30	7.20	112.80	18.40	12.80	23.40	63.60
448	51					16.60	128.60
449	67						436.40
450	19					0.09	2.58
451	27	4.80	6.00	30.20	20.00	2.00	107.80
452	19	14.40	9.00	4.80	4.40	11.40	173.30
453	32		0.33			9.67	34.33
454	33		6.00			52.80	711.60
MEAN		98.98	33.42	38.39	35.20	88.86	250.87

Table 10. JOINT RESEARCH AREA. Catch rates by families for demersal fish, kg/hour.

ST. NO.	DEP.	Croakers	Snappers	Grunts	Groupers	Catfish	Other
433	50	160.80				10.80	95.40
434	44	123.00	40.00	21.80			2541.80
435	30	548.20	103.80	46.00			1646.00
436	56	42.00	8.50	17.50			62.98
437	70	25.00	1.00				24.00
438	22	21.20	6.30			2.40	362.30
439	20	143.20	19.20	10.40			341.64
440	28	125.00	18.00				178.00
446	44	292.40				16.80	196.40
447	30	6.40				21.60	210.20
448	51	75.00				18.80	51.40
449	67	428.80		6.40			1.20
450	19	2.23					0.44
451	27	18.40	43.60		1.20		107.60
452	19	77.00	23.10	0.60	1.20	30.00	85.40
453	32	23.34				4.00	16.99
454	33	618.00				36.00	116.40
MEAN		160.59	15.50	6.04	0.14	8.26	355.19