6. Comparative bottom trawling

As an amendment to the work done in the previous survey, 6 night hauls were worked at approximately the same positions as 6 of the day hauls. Catch rates by main groups for the respective stations are shown in Table 7, while Table 8 shows catch rates by main demersal groups. As during the previous survey the day hauls tended to give higher catches compared to night, especially for small pelagic fish, but also of demersal species. As the hauls are few, this is not a conclusion on statistical basis. Further analysis of the data will be done for the final report.

Table 7. Comparative bottom hauls. Catch rates by main groups during day/ and nighthours.

DAYHOURS

ST. NO.	DEP.	Pelagic	Demersal	Shark	Squid	Shrimp	Other
705	37	133.00	204.80	20.00	4.20	5.00	53.20
707	27	210.40	255.20		3.20	3.20	80.00
708	24	146.80	336.00		4.00		113.60
716	40	85.90	32.50	6.00	4.40		30.00
719	46	48.00	226.00	7.00	5.00	2.20	5.00
720	46	79.60	197.60	27.80		0.80	2.60
MEAN		117.28	208.68	10.13	3.47	1.87	47.40

NIGHTHOURS

ST. NO.	DEP.	Pelagic	Demersal	Shark	Squid	Shrimp	Other
722	31	5.60	205.00	12.40		6.60	27.80
723	32	10.80	76.80			7.20	23.60
724	33	5.80	74.00			7.00	43.60
727	44		7.00				1.40
728	45	8.40	146.40	5.20		4.00	19.20
729	36	60.00	248.60			20.00	84.00
MEAN		15.10	126.30	2.93		7.47	33.27

Table 8. Comparative bottom hauls. Catch rates by main demersal families during day/ and nighthours.

DAYHOURS

ST. NO.	DEP.	Croakers	Snappers	Grunts	Groupers	Catfish	Other
705	37	169.20	28.00	0.60		7.00	215.40
707	27	201.60	24.80		12.80	16.00	296.80
708	24	332.80	2.40		0.80		264.40
716	40	30.50				2.00	126.30
719	46	221.00	5.00				67.20
720	46	170.80	10.20		0.80	15.80	110.80
MEAN		187.65	11.73	0.10	2.40	6.80	180.15

NIGHTHOURS

ST. NO.	DEP.	Croakers	Snappers	Grunts	Groupers	Catfish Other
722	31	166.00	33.00	6.00		52.40
723	32	69.20	7.20		0.40	41.60
724	33	48.80	16.00		9.20	56.40
727	44	7.00				1.40
728	45	146.40				36.80
729	36	225.60	7.00		16.00	164.00
MEAN		110.50	10.53	1.00	4.27	58.77

Pooled samples of the size distributions of the most important species are shown in Annex III.

Port of Spain
28 August 1988

Figure 2. Course tracks and fishing stations. JOINT FISHING ZONE.

Figure 3. Hydrographic profiles.

NORTH OF TOBAGO 24.8 1988

EAST OF TRINIDAD 25-26.8 1988

Figure 4. Distribution of pelagic fish from acoustic system.

Figure 5. Distribution of pelagic fish from acoustic system.