Seychelles tuna bulletin : first quarter 1988

Data used to generate the tables and figures presented here are based on daily catch and effort report forms (1ogs') returned from the fishing vessels which are licensed to fish in the Seychelles EEZ. Sometimes there is a delay in these being received at SFA, especially after the second quarter of the year when most vessels are fishing in the Mozambique Channel. Readers should be aware that many of the figures presented here are subject to revision (usually upwards) as more data become available. The date upon which the SFA database was closed prior to the generation of the statistical tables is now shown at the head of each table. Principal Points Purse seiners - The revised total catch for the Western Indian Ocean for 1994 is now 272,192 t. This is the third year in succession that it has exceeded 270,000 t. - Some 12,196 days were fished in 1994 compared to 14,368 in the whole of 1993. The decrease was chiefly due to lack of Japanese effort in the fishery; decreasing from 2,029 days in 1993 to only 19 days in 1994. The mean CPUE rose from 19.27 t/day in 1993 to 22.32 t/day in 1994. Yellowfin (Thunnus albacares) comprised some 34% of the catch (91,865 t) and skipjack (Katsuwonus pelamis) some 55% (149,362 t). - The catch in the first quarter of 1995 is so far reported at 64,751 t; this compares with 75,847 t in the first quarter of 1994. - The catch in the first quarter of 1995 comprised 19,549 t (30%) yellow fin (Thunnus albacares) and 35,207 t (54 %) skipjack (Katsuwonus pelamis). In the first quarter of 1994 yellowfin comprised 48,943 t (65%) and skipjack 20,393 t (27%). - Readers should be well aware that the catch compositions given here are NOT based on scientific sampling but on the assessment of the fishermen who write the daily catch-effort reports and who decide into which group fish should be placed. They may therefore be biased. - In the first quarter of 1995 some 3,308 days have been fished compared to 2,846 days in the first quarter of 1994. - The CPUE in the first quarter of 1995 is 19.57 t/day compared to 26.65 t) day in the first quarter of 1994. - It should be noted that the figures in table 3 represent the transshipments of vessels who's trips ENDED in the month indicated and NOT the actual month of physical transshipment of the catch. - Reference to the map of purse seine fishing by one degree squares shows that there was virtually no fishing activity in the Chagos area in the first quarter of 1995. This contrasts with the intense activity which took place there during the first quarter of 1994. An oceanographer familiar with the area has suggested that a rise in water temperature may have caused a change in annual migration patterns. Probably as a consequence of the lack of fishing in the Chagos area there was more activity in the most Westerly W10 than usual in the first quarter. - Transshipment through Victoria was 46,207 t for the first quarter of 1995 compared with 47,809 t in the first quarter of 1994. Transshipment through Antsiranana is so far reported at 10,874 t in the first quarter of 1995 compared to 30,334 t in the equivalent quarter last year. This figure is based on logbooks which we have so far received. However, the Association Thoniere in their Note Trimestrielle for the first quarter of 1995 indicate that by the end of the quarter 16,797 t had been transshipped at Antsiranana. Maps 1 and 2 show the geographic areas of the W10 from which the purse seine catch came from in the whole of 1994 and the quarter of 1995 being reported on. The area of the circles plotted in each one degree square is proportional to the catch in that square. Interested readers are referred to previous bulletins in order to see the seasonal shift in areas of fishing activity. Data in the one degree squares (3,600 square nautical miles of ocean) include all nations reporting catches in the area during the described period. Long liners Since the Tuna Bulletin for the last quarter of 1994 was produced we have received more long line daily catch effort report forms for 1994. Data from these have been used to update the tables, maps and graphics. Virtually no data have yet been received for 1995. This underlines the very slow reporting rate of long liners in general. Readers should be aware that these statistics represent only a small proportion of long liner activity in the WIO because: (a) Not all long liners fishing in the WIO have a license to fish in the Seychelles EEZ and are therefore under no legal obligation to report to SFA. (b) Not all those with a Seychelles license provided daily log sheets. This could be due to non-fishing or fishing but not reporting. (c) Some distant water fishing nations (DWFN) provide SFA with daily catch and effort forms covering their activity in the whole Indian Ocean while others confine their reports to the Seychelles EEZ. Principle points are: - Longliner activity is concentrated at the beginning or end of the year (first and last quarter) with little or no fishing from May to August. - Catch rates appear to decrease as effort increases and increase as effort decreases; - The catch and CPUE in 1994 both show a decrease relative to 1993 (catch down from 3,913 t to 2,825 t and CPUE down from 0.394 t/1000 hooks to 0.318 t/1000 hooks). Maps 3 and 4 show the areas from which long line fishing was reported in 1993 and 1994. Because the reported catches per one degree square are small they do not show up well on the map; effort has therefore been used as a better indicator of area of fishing activity. The graphics provide a summary of the SFA long line database covering the last ten years. The last twenty seven months are covered in detail so that it is possible to compare the quarter being reported on with two past equivalent quarters and detect seasonal fishing patterns.

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