International Council for the Exploration of the Sea C.M. 1989/H

~, ,. f , I International Council for the C.M. 1989/H:34 Exploration of the Sea Pelagic Fish Commitee CATCH OF SMALL PELAGIC SPECIES BY THE LIVE BAIT BOATS OF THE BASQUE COUNTRY IN 1987 AND 1988 by I. Martin A.Z.T.I.-S.I.O. Txatxarramendi ir1a, Sukarrieta, Bizkaia, Basque Country (Spain) • ABSTRACT The study of the catch of small pelagic species by the live bait boats (for tuna fishing) was started by the Basque Country in 1987. In this paper, estimates are presented on total catch by species, spatia1 distribution of the catches, length composition and age composition (only of anchovy) of the catches of anchovy, Engraulis encrasicholus, pilchard, Sardina pi1chardus, horse mackerel, Trachurus trachurus, and mackere1 Scomber scombrus. .: RESUME L'etude de 1a capture des petits poissons pelagiques pour la peche a l'appat vivant a commence au Pays Basque en 1987. On presente dans cet article, pour l'anchois, Engraulis encrasicho1us, 1a sardine, Sardina pilchardus, le chinchard, Trachurus trachurus, et le maquereau, Scomber scombrus, des resultats sur les estimations de la capture totale par espece, la distribution spatiale de la capture, la composition par taille et age de la capture (seu1ement pour • l'anchois). INTRODUCTION Sampling of the catch of small pelagic species by the boats which use live bait to catch tuna was started by the Basque Country in 1987. Some pre1iminary results refered to anchovy in 1987 were presented by Martin and Lucio (1988). In the present paper, results of two years of sampling (1987 and 1988) and refered to -anchovy, sardine, horse rnackere1 and mackere1 are presented~ . 1 ,. METHODS This study was carried out in two ports of the Basque Country, Bermeo and Ondarroa. The methodology used in this work was fist described in Martin and Lucio (1988). Effort expressed as number of days spent fishing for bait, estimates of total catch of the boats of the ports studied and spatial distribution of the catches are derived from interviews done to.a number of skippers of each port. Length and age cornposition of the catches are estimated from samples obtained during fishing trips on board of some boats or at the ports as the, boats come to land thetuna caught. The latter samples were taken from the tanks where the bait is kept alive on board of the vessels. Fish otoliths were removed from some of these length • samples for age determination. When length samples or otoliths removed did not 'cover certain sampling cells where catches had actually occurred, sampies from the purse: seine fleet were' also used to estimate the length or age com90sition of the catch of the.live bait fleet. , , The rnethod.used to estimate total catches and spatial distribution of the catches for 1988 was'slightly changed from the method used in Martin and Lucio (1988) in two aspects: The estimate of the total anchovy catch öf each port by ,statistical.square in_t-lartin_and.Lucio ,(1988L.\vas.. derived_as: .. _. .._, _ C(interviewed,i) * Total number of trips of all boats 'C(i)- ( 1) Number of fishing'trips of the boats interviewed \vhere C(i) is the estimated total catch of ICES statistical square i • C(interviewed,i) is the catch in statistical square i of the boats interviewed In the present work, the estimated catch by statistical square has been obtained for 1988 as follows: C(interviewed,i)* Total number of'days spent fishing th~ C(1)-------------. ' .. by all boats of the port ---- (2) Number of days spent'fishing by the boats interviewed In 1988, sampling of the port of Ondarroa was very poar, SO, for this year, only data from the port of Bermeo have been used. 2 -- --- --- --------- ~-----------I " An estimate of the total catch of,all Spanish boats (those of the ports of the Basque Country plus those of other ports) has been obtained by extrapolating the results obtained for Bermeo and Ondarroa in 1987 and Bermeo in 1988 to all Spanish boats using the fol1owing factor: Total nurnber of Spanish live bait boats C(ALL) ------------------------------------------------ Number of live bait boats of the ports studied The total number Spanish boats in each year has beenconsidered to be. 162 (Anon, 1988) minus the number of boats of the ports studied which were known to be not ·fishing with this method but were counted as live bait boats in Anon (1988). This gave about 160 boats in 1987 and 154 in 1988 • The number of boats of the ports studied fishing with live bait were about 66 in ·1987 and about 54 in 1988. For 1988, on1y the port of • Bermeo was taken into account since sampling of Ondarroa was very poor. When boats fish for bait, part of the catch is put on board into tanks with running water, while the rest is 1eft free in the sea. Separate estimates of catches kept on board and catches "left free" have been obtained. .. _-...... During 1988 19F of the days spent fishing tuna by the live bait boa~s of Bermeo were covered by the interviews. A totalof 25 length sampies of anchovyand ·2282 fish were measured during 1988 covering 11 samplirig cel1s (as defined in Martin and Lucio 1988) of the 20 samp1ing cells in which catches actua11y took p1ace according to the interviews availab1e. __ RESULTS Estimates of total catch by species for 1987 and 1988 are shown in Tab1e 1. Separate estimates for catches put on board and catches left free for each species are given. For comparative purposes between both years studied, on1y data refered to Bermeo and extrapo1atingmethod (2) have been used in both years. Estimates of total nUrnber of days spent fishing for bait by the boats of Bermeo are given in Tab1e 2. Spatia1 distribution of the catch of each species (llput on board" and . 1I1eft free" catch added up together) is shown in Figure 1 for both years of data. For comparative purposes, on1y data refered to Bermeo and extrapo1ating method (2) have been used in both years. Total catch has been shown since it might give a better idea than catch put on board of the abundance of these species in the area covered by the fleet 3 Estimated length composition of the annual catch of anchovy of the boats 'of Bermeo during 1987 ~nd 1988 is shown in Figure 2. Age composit~on of the catch of anchovy as estimated for all Spanish boats is g~ven in . Table 3. Estimates for 1987 (from Martin and Lucio, 1988) were calculated using data from Ondarroa'and Bermeo and extrapolating method (1); those for 1988 have been calculated using data from Bermeo and extrapolating method (2). In Figure 3, total catch put on board of age groupO anchovy for 1987 and 1988 and"catch per unit effort index of the same age group for both years is shown in order to give an idea of relative year class strength. CPUE data have been calculated by using effort of the boats of Bermeo as an index of effort for all Spanish live bait . boats. The catch of all these species is a small fraction of the quantity caught by other fisheries. However, this type of study may prove tt useful in providing indications of year class strength for some of these species. This, in turn, is a very desirable information for species with short life span like anchovy, whose fisheries are very dependent on recruitment. REFERENCES. ANON. 1988. Report of an ad hoc Working Group on the_ßescription of the fisheries directed at anchovy in ICES Divisions VIIlb and VlIlc. Nantes 25-29 January 1988. MARTIN I. & LUCIO P. 1988. Distribution of landings and effort in the anchovy fishery of the Basque Country in 1987, with special reference to the length frequency distributions and age composition of the landings. ICES CM 1988/H:12 • 4 Table 1. Estimatc of total catch put on board and catch left free of anchovy, pilchard, mackerel and horse mackerel by the live bait vessels of Bermeo in 1987 and 1988. Only data refering to this port have been included to make results of poth years comparable. Catch in tonnes. CATCH PUT ON BOARD CATCH LEFT FREE JUL AUG SEP OCT NOV TOT JUL AUG SEP OCT NOV TOT ANCHOVY 1987 85 28 3 28 13 157 27 4 1 32 1988 76 14 45 38 173 21 3 22 38 84 PILCHARD 1987 23 23 9 6 2 63 5 7 1 11 o 24 1988 12 27 7 46 18 9 27 HORSE HACKEREL 1987 8 8 11 27 5 3 3 10 1988 3 32 11 46 4 5 1 TO MACKEREL 1987 8 8 12 12 1988 Table 2. Estimate of total number of days spent fishing for bait by the boats of the port of Bermeo in 1987 and 1988. l-10NTH 1987 1988 JUN 5 JUL 298 323 AUG 160 100 SEP 62 151 OCT 70 177 NOV 80 29 TOTAL 675 780 Tab1e 3. Estimated age composition of the anchovy catches of the Spanish live bait fleet. Results for 1987 from Martin and Lucio (1988); those for 1988 have been obtained using data of vesse1s ·from Bermeo only and extrapo1ating method ( 2) . UNITS: THOUSANDS OF INDIVIDUALS 1987 MONTHS AGE 0 AGE 1 AGE 2 AGE 3 TONS 7 13067 259 77 181 8 10129 496 48 154 9 7466 1479 91 5 124 10 615 782 56 11 2554 31 TOTAL 10020 24975 1461 912 546 1988 HONTHS AGE 0 AGE 1 AGE 2 AGE 3 TONS 7 13435 86 3 217 8 10601 1506 54 40 9 39008 2090 37 128 10 47972 322 26 108 11 TOTAL 97581 17353 203 3 493 f:J E6 E7 E8 E9 '~I '~I 22 7 - - 20 138 109 ~ ~ 18 3 6 9 40 30 CONTIS CONTIS 16 ~ 26 14 ~ 3 .

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