Analysis horse mackerel catches in the Cant G. Costas 1 , P. Abaunza 2 , R. Morlán 1 Instituto Español de Oceanografía (IEO), Centro Oceanográfico (CO) de Vigo, Cabo Estay-Canido s/n, Apdo. 1552, 36 3 CO A Coruña, Paseo Marítimo Alcalde Francisco Vázquez nº 10, 15001 A Coruña, Sp * Email: gersom.co XIII International Symposium on Oceanography of the Bay of Biscay, Santander 11 - 13 of A 47 -11 -10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 22 Long Atlantic horse mackerel (Trachurus trachurus) is a pelagic speci family. The geographical distribution of the Atlantic horse mackere slope of the European and African coasts from Norway to Cape V -200 - 200 -5 00 -500 -5 00 -100 0 - 1 0 0 0 43 44 45 46 D9 E0 E1 E2 E3 E4 E5 E6 E7 E8 E9 F0 14 16 18 20 22 Lat ICES squares ICES squares VIIIc West VIIIc East VIIIab This study is based on horse mackerel catches made by the Spanish fishing fleet operating in the Cantabrian Sea and Bay of Bis and VIIIc) for the period 2000 to 2010. This area corresponds to the southern fraction of the Western Stock. In this area horse m different fishing gears (purse seine, different trawling methods, long-line and gillnet). Spanish mean landings of horse mackerel W slope of the European and African coasts from Norway to Cape V the International Council for the Exploration of the Sea (ICES) h Atlantic is considered to be separated into three stocks: The South and the Western stock. Western stock on the northeast continenta the Bay of Biscay to Norway. (ICES, 2011) The horse mackerel on Western stock fisheries are important trad Atlantic, with estimated mean landings of around 176,000 (±28,0 2011). The population dynamics of western horse mackerel are c year classes, such as the very strong 1982 year class constituting 1980s to well into the 1990s. different fishing gears (purse seine, different trawling methods, long-line and gillnet). Spanish mean landings of horse mackerel W than 12% (around 21,000 t) of the total Western stock landings for the period 2000-2010. Spanish landing data are monthly collec Oceanografía” (IEO) and by “Instituto Tecnológico y Alimentario” (AZTI) from different sources. In addition a routine landing and b monthly basis is carried out to estimate length distribution for the landing data. These length distributions are then transformed i length keys. In order to analyze Spanish horse mackerel landings the geographic area was divided into three areas: Subdivision V and Division VIIIab. Figure 2. Bubble plot represents catch proportions in abundance (numbers) at age during the period 2000-2010. With Larger bubbles corresponding to larger values. 11 12 13 14 15+ 25000 30000 35000 t) VIIIab VIIIc East VIIIc West 10000 15000 20000 subdivision VIIIc West ndings (t) Artisanal Trawler Purse seine Figure 1. Bar graphs showing annual landings by area and gear for the period 2000-2010. The pattern of total Spanish landings by year (overlapped grey bars) show a similar value (23000 t) corresponding to larger values. In general, catches are dominated by juveniles (ages 1 to 2), although in recent years there is an increment in catch of older ages. The age 0 is not completely recruited by the fishery and its presence in landings is also influenced by the application of harvest policies like the minimum landing size. The 2001 year class appears to have been strong, although not Age 0 1 2 3 4 5 6 7 8 9 10 11 2000 2001 5000 10000 15000 20000 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 Year Landings (t 0 5000 10000 15000 20000 subdivision VIIIc East Landings (t) Artisanal Trawler Purse seine 0 5000 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 Year Lan Figure compar landing between show d overall line). Th aggrega landings grey bars) show a similar value (23000 t) in the first years (2000-2003), then a slight decrease (2004-2007) and a rising in the lasts years. During this period, landings of Subdivision VIIIc West were slightly higher than of Subdivision VIIIc East. Landings of Division VIIIab represented a small fraction of the total landings from the study area. In Subdivision VIIIc West the horse mackerel landings are mainly made by purse-seiner and trawler. The landings are distributed similarly between these fishing gears along the time series. The artisanal fleet (long-line and gillnet) represented a very low catch have been strong, although not as strong as the 1982 year class. 20 30 40 50 Length (cm) Purse Seine Trawler 0 5000 10000 15000 20000 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 division VIIIab Year Landings (t) Artisanal Trawler Purse seine 0 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 Year landings VIIIc Ea Subdivis special a (<2%). In 2009-2010 there has been an increase in total landings. In Subdivision VIIIc East and Division VIIIab purse seiner fleet represented the largest amount the horse mackerel landings. Trawl fleet in these areas were responsible for about 15% of total landings and hardly artisanal fleet landings were noticed (<1%). In the last years a significant increase in the purse seine landings was observed. 10 VIIIab VIIIc East VIIIc West Subdivision 2000 2001 0.0 0.2 0.4 0.6 0.8 subdivision VIIIc West 2000 2001 0.0 0.2 0.4 0.6 0.8 division VIIIab 2000 2001 0.0 0.2 0.4 0.6 0.8 subdivision VIIIc East other hand trawl fleet in Subdivision VIIIc West mean length in landings. 2002 2003 2004 2005 2006 2007 2008 2009 2010 0.0 0.0 0.2 0.4 0.6 0.8 0.0 0.2 0.4 0.6 0.8 0.0 0.2 0.4 0.6 0.8 0.0 0.2 0.4 0.6 0.8 % Catch (Weight) 2002 2003 2004 2005 2006 2007 2008 2009 2010 0.0 0.0 0.2 0.4 0.6 0.8 0.0 0.2 0.4 0.6 0.8 0.0 0.2 0.4 0.6 0.8 0.0 0.2 0.4 0.6 0.8 % Catch (Weight) 2002 2003 2004 2005 2006 2007 2008 2009 2010 0.0 0.0 0.2 0.4 0.6 0.8 0.0 0.2 0.4 0.6 0.8 0.0 0.2 0.4 0.6 0.8 0.0 0.2 0.4 0.6 0.8 % Catch (Weight) Figure 6. Percentage of purse seine and trawler landings by age group, area and year. In purse seine fishery the main percentage in catch (weight) was for young ages in all areas although in recent years the percentage of older ages increased. In bottom trawl fishery there is not a general pattern. In Subdivision VIIIc West the main percentage in catch has been for older ages especially in last years. However in Subdivision VIIIc East the main percentage in catch was for medium ages in the beginning of this period whereas in last years the main percentage moved to younger ages. Bottom trawl fishery in Divisions VIIIab showed a greater proportion of younger ages in its horse mackerel catch composition. 0.0 0.2 0.4 0.6 0.8 0 1 2 3 4 5 6 7 8 9 101112131415+ Age Gear Purse seine Trawler 0.0 0.2 0.4 0.6 0.8 0 1 2 3 4 5 6 7 8 9 101112131415+ Age Gear Purse seine Trawler 0.0 0.2 0.4 0.6 0.8 0 1 2 3 4 5 6 7 8 9 101112131415+ Age Gear Purse seine Trawler Discussion: Discussion: • Trawler y purse seine fleets present a different fishing pattern in all areas. In general catch length distribution in purse seine purse seine landings the smaller sizes (younger ages) are majority whereas in trawl fleet landings this is no so evident. (Figs 3 •There is a trend in the presence of older ages (above 4 years old) to become more abundant in the western area (Figs 3,6,7). as Division VIIIab (Figs 3, 4, 6, 7). All this pattern s has already been described by several authors (Murta et al., 2008). • It is worth to mention the gap in size-classes 18-23 cm (ages 2-3) found in landings distributions (Figs 3 and 7) , which roughly sexual maturity (Abaunza et al., 2003). This produces some difficulty for the tracking of year classes at juvenile and young adul • In recent years in purse seine landings there has been a shift in landing composition towards older ages. This shift is also no results in an increase in mean length in landings (Fig. 5). It should be noted that in last years there has been a high increase in (Fig. 1). ntabrian sea and Bay of Biscay (2000-2010) n 3 , R. Gancedo 2 & S. Sánchez 4 6280 Vigo (Pontevedra), Spain; 2 IEO, CO Santander, Promontorio de San Martín s/n , 39180 Santander, Spain IEO, Spain. 4 AZTI-Tecnalia, Instituto Tecnológico Pesquero y Alimentario, Pasaia, Spain ostas@vi.ieo.es April 2012 subdiv VIIIc West Trawler subdiv VIIIc West Purse seine ies belonging to the Carangidae el covers the whole platform and Verde (Whitehead et al., 1986). In Siz e (c m) 5 10 15 20 25 30 35 40 45 50 55 60 Ye a r 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 N i n d i v i d u a l s ( * 1 0 ^ 5 ) 0 20 40 60 80 100 120 140 160 180 200 subdiv VIIIc East Purse seine Siz e (c m) 5 10 15 20 25 30 35 40 45 50 55 60 Ye a r 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 N i n d i v i d u a l s ( * 1 0 ^ 5 ) 0 50 100 150 200 250 300 350 400 subdiv VIIIc East Trawler scay area (ICES divisions VIIIab mackerel catches are made up of Western stock representing more Verde (Whitehead et al., 1986). In horse mackerel in the north-east hern stock , the North Sea stock al shelf of Europe, stretching from ditional fisheries in the Northeast 000) t from 2000 to 2010 (ICES, characterized by sporadic, strong the bulk of catches from the mid- 400 div VIIIab Purse seine Siz e (c m) 5 10 15 20 25 30 35 40 45 50 55 60 Ye a r 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 N i n d i v i d u a l s ( * 1 0 ^ 5 ) 0 50 100 150 200 250 300 350 400 200 div VIIIab Trawler Siz e (c m) 5 10 15 20 25 30 35 40 45 50 55 60 Ye a r 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 N i n d i v i d u a l s ( * 1 0 ^ 5 ) 0 20 40 60 80 100 120 140 160 180 200 Western stock representing more cted by the “Instituto Español de biological sampling program on a into age distributions, using age- VIIIc East, Subdivision VIIIc West Siz e (c m) 5 10 15 20 25 30 35 40 45 50 55 60 Ye a r 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 N i n d i v i d u a l s ( * 1 0 ^ 5 ) 0 50 100 150 200 250 300 350 400 Siz e (c m) 5 10 15 20 25 30 35 40 45 50 55 60 Ye a r 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 N i n d i v i d u a l s ( * 1 0 ^ 5 ) 0 20 40 60 80 100 120 140 160 180 Figure 3. Annual length distributions of horse mackerel landings by gear and area. The results show a first approximation to the exploitation pattern of purse seiner and trawler operating for horse mackerel in this area along the period (2000-2010). There is a gradual increase in landing length from Division VIIIab purse seine fleet and in Subdivision VIIIc West Year 2002 2003 2004 2005 2006 2007 2008 2009 2010 increase in landing length from Division VIIIab purse seine fleet and in Subdivision VIIIc West trawl fleet. However there is a decrease in landing lengths in Subdivision VIIIc East trawl fleet. It is worth to mention the gap found in purse seine length distributions in the range 18-23 cm. the ranges of length frequencies were quite similar at the beginning in trawl fleet from Subdivisions VIIIc West and VIIIc East, although in the lasts years the VIIIc West trawl fleet range was shifted towards bigger sizes whereas the VIIIc East range toward as smaller ones. Purse seine catches show a wide range in length frequencies with a large abundance of the smaller sizes. 4. Asymmetric beanplots for rison of horse mackerel g size frequency distributions n gear and area. Beanplots distribution densities and the means (solid horizontal black hese frequency distributions are ated over time. Purse seine fleet s in Subdivisions VIIIc West and Figure 5. Annual mean length in landings by fishing gear and area along this period (thick solid line). The semitransparent grey areas bounded by dotted line represent the length range Year s in Subdivisions VIIIc West and ast and trawl fleet landings in sion VIIIc West showed a asymmetric beanplot. On the bounded by dotted line represent the length range (max – min) in each year. In Subdivision VIIIc West Trawl fishery, in recent years an increasing trend in the mean length is observed, however, this trend is the opposite (decreasing) in Subdivision VIIIc East and Division VIIIab. Purse seine fishery shows an increasing trend in the mean length in all areas, although in Subdivision VIIIc West there is a more uneven track record in this period. In addition, length distribution of landings showed a wider length range in purse seine fishery than in trawl fishery. and VIIIc East showed a bigger 0 12 3 4 5 6 7 8910 11 12 13 14 15+ Age 0 1 2 3 4 5 67891011121314 15+ Age Trawler division VIIIab Trawler subdivision VIIIc East 0 5000 10000 15000 20000 25000 15000 20000 25000 als(*1000) 0 1 2 3 4 5 678 9 10 11121314 15+ Age 0 1 2 3 4 5 6 78 910 11121314 15+ Age Purse seine division VIIIab Purse seine subdivision VIIIc East 0 20000 40000 60000 80000 40000 60000 80000 als(*1000) Figure 7. Histograms of length frequency data of landings by area and gear aggregated over time. The solid vertical lines marks are the estimated mean lengths at age. Landing length distributions for purse seine fleet were showed wider and bimodal compared with trawl fleet. In trawl fleet the old ages were the most important for the landings in 0 1 2 3 45 6 7 8 9 101112 1314 15+ Age Trawler subdivision VIIIc West 0 5000 10000 0 5000 10000 15000 20000 25000 10 20 30 40 50 Length (cm) Individua 0 1 2 3 4 5678 910 11 12 13 1415+ Age Purse seine subdivision VIIIc West 0 20000 40000 0 20000 40000 60000 80000 10 20 30 40 50 Length (cm) Individua Subdivisions VIIIc West and VIIIc East, while, in Division VIIIab the young ages were largely significant in landings. In purse seine landings were dominated young ages (ages 0-2) in Subdivisions VIIIc East and VIIIc West although there were a significant occurrences of older ages (> 4 years old). It is worth to mention the considerable decrease in landings for ages 2 to 4, mainly in purse seine. References: e presents an asymmetric distribution and a wide length range. In 3, 4,5, 7) In addition, young fish are caught mainly in waters shallower such y corresponds to the length at which the horse mackerel attain the lt ages in the catch in numbers at age time series. (Fig. 2). otorious in Subdivision VIIIc West trawl landings (Figs 2,6,7). This n purse seine landings and in Subdivision VIIIc West trawl landings References: -Abaunza, P., L. Gordo, C. Karlou-Riga, A. Murta, A.T.G.W. Eltink, M.T. Garcia Santamaria, C. Zimmermann, C. Hammer, P. Lucio, S.A. Iversen, J. Molloy and E. Gallo (2003). Growth and reproduction of horse mackerel, Trachurus trachurus (carangidae). Reviews in Fish Biology and Fisheries. 13:27-61. -ICES 2010. Report of the Working Group on Widely Distributed Stocks (WGWIDE). ICES CM 2011/ACOM:15. -Murta, A.G., Abaunza, P., Cardador, F. and Sanchez F. (2008) Ontogenic migrations of horse mackerel along the Iberian coast. Fish. Res. 89: 186– 195. -Whitehead, P. J. P., Bauchot, M.-L., Hureau, J.-C., Nielsen, J., and Tortonese, E. 1986. Fishes of the North-eastern Atlantic and the Mediterranean. Unesco, Paris. 1473 pp. View publication stats View publication stats