SCRS/2002/164 (Rev) Col. Vol. Sci. Pap. ICCAT, 55(1): 292-302 (2003)

PRELIMINARY ANALYSIS OF SOME PELAGIC FISH DIET IN THE EASTERN CENTRAL ATLANTIC

Richard Sabatié1, Michel Potier2, Caroline Broudin3, Bernard Seret3, Frédéric Ménard4, Francis Marsac2

SUMMARY

In the framework of the BETYP program, some scientists of the IRD took part to cruises on board the Japanese R/V Shoyo-Maru. Three cruises were done from October to December 2000. These cruises covered the Eastern Central Atlantic from 10° to 40°W and from 20°N to 10°S. Fish were caught with long-line and micronekton with an IKMT (Isaacs-Kidd Mid-water Trawl). 135 stomach contents and 30 tows have been analyzed. Istiophoridae and Thunnidae are opportunistic feeders, fish and crustaceans being the main components of the diet. Swordfish seem to have a more specialized diet with molluscs dominating in the northern part of the region and fish in the southern part. Lancetfish, which exhibits, like tunas and swordfish, large vertical movements, eats crustaceans and fish. In this region of the Atlantic, tuna caught with longline have a more heterogeneous diet than tuna caught with purse seine. This result could be linked to different behaviour (with emphasis on vertical movements) among the species and the size of individuals. Comparison between the diet of the pelagic predators and the catch composition of the tows is difficult, as the determination of some food items has not yet been done. Such work is still in process and will allow a better understanding of the prey-predator interactions.

RÉSUMÉ

Dans le cadre du programme BETYP, des scientifiques de l'IRD ont effectué trois embarquements à bord du navire de recherches japonais, le Shoyo-Maru, entre octobre et décembre 2000. Ces missions ont été déployées dans la zone Est de l'Atlantique Central entre 10 et 40° de longitude O et 21° de latitude N à 10° de latitude S). Les poissons ont été pêchés à la palangre et des chalutages de micronecton ont été réalisés avec un chalut IKMT (Isaacs - Kidd Mid-Water Trawl). Le contenu de 135 estomacs et de 30 traits de chalut a été examiné. Les résultats montrent que les Istiophoridae et les thons sont opportunistes et se nourrissent d'un grand nombre de proies où poissons et crustacés sont de première importance. L'Espadon, plus spécialisé, semble s'alimenter préférentiellement sur des mollusques en zone nord et sur les poissons en zone sud. Les Alepisaurus, capables aussi d’effectuer d’importants mouvements verticaux dans la colonne d’eau, se nourrissent de crustacés et de poissons. Dans cette région de l'Atlantique, les thons capturés à la palangre semblent avoir une alimentation plus diversifiée que celle observées chez les thons pêchés à la senne. Ce résultat est à relier à des différences comportementales (associées principalement aux déplacements verticaux) entre espèces et taille des individus. Il est encore difficile de comparer avec précision les contenus stomacaux et la composition des traits de chalut à micronecton. La détermination d'une partie des taxa recueillis est une autre difficulté. Le travail est en cours et il devrait permettre de mieux comprendre les interactions entre prédateurs et proies.

RESUMEN

En el marco del programa BETYP, los científicos del IRD han efectuado tres embarques a bordo del barco de investigación japonés Shoyu-Maru, entre octubre y diciembre de 2000. Estos cruceros cubrieron el Atlántico central y oriental desde 10º a 40º W y desde 10º N hasta 10º S. Los peces se capturaron con palangre y micronecton con un IKMT (palangre epipelágico Isaacs-Kid). Se analizaron 30 operaciones y 135 contenido estomacales. Los istiofóridos y los túnidos son especies de alimentación oportunista, y los peces y crustáceos son los principales

1 ENSAR Halieutique, 65 rue de Saint-Brieuc, CS84215, 35042 Rennes Cedex , France ; [email protected] 2 IRD, BP172, 97492 Sainte Clotilde Cedex, La Réunion ; [email protected] 3 MNHN , 43 rue Cuvier 75231 Paris cedex 05, France 4 IRD, Centre de Recherche Halieutique Méditerranéenne et Tropicale, Av. Jean Monnet , BP171, 34203 Sète cedex, France 292 componentes de su dieta. El pez espada parece tener una dieta más especializada dominada por los moluscos en la parte septentrional de la región y por los peces en la parte meridional. Los Alepisaurus, capaces también de efectuar importantes movimientos verticales en la columna de agua, se alimentan de crustáceos y peces. En esta región del Atlántico, los túnidos capturados con palangre parecen tener una alimentación más diversificada que la observada en los túnidos capturados con cerco. Este resultado puede relacionarse con las diferentes conductas (asociadas sobre todo a los desplazamientos verticales) entre especies y tallas de los especímenes. Todavía resulta difícil realizar una comparación precisa entre la dieta de los depredadores pelágicos y la composición de captura de las operaciones de arrastre puesto que no se ha realizado todavía una determinación de los productos alimentarios. Dicha labor está todavía en proceso de realización y debería permitir una mejor comprensión de las interacciones entre depredadores y presas.

KEY WORDS

Istiophoridae and Thunnidae, feeding behaviour, stomach content, pelagic environment, longlining, eastern central Atlantic.

1. INTRODUCTION

The “Institut de Recherche pour le Developpement” (IRD) has initiated in 2000 a program on trophic ecology of pelagic predators (tuna and related species) (Marsac, 1999). One of the Thetis program objectives is the study of the predator-prey interactions in some deep-sea pelagic ecosystems of the Atlantic and the Indian Oceans. Other aims of this program is to improve the knowledge on the influence of the environment on large pelagic predators (tuna, billfish) distribution and to reach a better understanding of the interactions between fisheries and multi-species communities.

During the BETYP Programme, cruises of the Japanese R/V Shoyo Maru have been planed in the Eastern Central Atlantic. The Thetis programme takes opportunity of these cruises to collect stomachs from pelagic predators caught with long line and to sample the micronekton fauna of the region with an IKMT net.

This article presents the first results of an analysis of pelagic predators stomach contents collected and IKMT nets performed during three cruises done in October-December 2000 on board the R/V Shoyo-Maru.

2. MATERIAL AND METHODS

137 stomachs have been collected during the three trips made on board the R/V Shoyo-Maru from October to December 2000 and 24 tows have been carried out.

Fish have been caught by long-line during the day (from dawn to dusk) and tows have been carried out (IKMT net; length 13 m: mouth 2.8 m, x 1.5 m) at day between 8-9 a.m. or 12-13 p.m. and at night between 21-22 p.m. During the day, the trawl was immerged at about 400 m depth and during night at about 100 m.

The first cruise (cruise 2) took place in the temperate waters of the North Equatorial current and the two others (cruises 3 and 5) in the tropical waters of the South Equatorial divergence (Figure1).

The collected stomachs belonged to 13 species (Table1). Stomachs were removed on board from the abdominal cavity by cutting them at the last gill level and after the pyloric valve. The following information was then recorded: species, size of fish, weight, sex and maturity, stomach filling index,

293 hour of sampling. Stomach was then put in ceiled bag and frozen. A label with the main characteristics was enclosed with the bag.

At the laboratory, they were defrosted 24h before the analysis. The content was sorted and weighted by large category (fish, molluscs, crustaceans).

Inside large category, one noted for every item the degree of digestion and the weight. Remarkable organs were used to determine the number of preys in the stomach. Mandibles, parasphenoids or the maximum number of either left or right otolith was assumed to reflect the total number of fish preys. For cephalopods and crustaceans, respectively, the greatest number of either upper or lower beaks, telsons or pleopods was used. Prey items were identified to the lowest taxum. The reconstituted weight of the food will be done by calculating regressions relating dimensions of remarkable organs to the weight of each item (weight-relationship with otoliths, mandibles or parasphenoids for fish; weight relationship with mantle length or beak dimensions for cephalopods). This work is on process, and some results are presented (Table2).

For the present paper, we used fresh content separated by large category. Accumulated otoliths or beaks have been removed. Then, the abundance and the weight of some preys is underestimated.

For the reconstructing weight of fresh digested food we used the method of Bard (2001) and we gathered in one sample: (1) the neighbouring cruises 3 and 5, (2) the billfishes (except swordfish) in an Istiophorids group. Some species, represented by one stomach only, were removed for this study.

An Index of Relative Importance IRI (Pinkas et al., 1971) was calculated for each category;

IRI = (%N+%W) x %F

(%N) = the percentage by number, (%W) = the percentage by weight, (%F) = the percentage by frequency of occurrence

We used also the relative IRI (%IRI) (Cortes, 1997) where

n %IRIi = 100.IRIi / (S i=1IRIi)

A graphical representation (Costello, 1990; Hanson, 1998), which incorporates the indices %N and %F, was used. That method allows us to study the prey importance and the feeding strategy of the different predators.

The %IRE, percent Index of repletio n was calculated (reconstructed weight content x 100/wet weight of fish).

The content of IKMT net was sorted on board, in large categories (fish, molluscs, crustaceans, gelatinous) and put in boxes with alcohol 70%. Determination by species (presently only fish category) and relation with some factors (depth, diversity abundance) was done in laboratory.

3. RESULTS

3.1 Food analysis

The relative index (%IRI) allowed a better interpretation of the predator diet (Figures 2 and 3, Tables 3 and 4).

294 For most of the predators (swordfish, wahoo, yellowfin and bigeye), fish item was the main component of the diet. For this category the relative Index ranged from 40.7% to 96%. It also showed the highest percentages by number, weight and frequency of occurrence. Molluscs (squids and pelagic Octopoda) had the second rank, followed by the crustaceans.

Some Istiophorids fed on a large number of big fish. Albacore (Thunnus alalunga) fed mainly on Crustaceans (relative large number of low weight preys) and Molluscs (a few number of big preys), while Crustaceans and fish were dominant in the diet of the lancetfish.

3.2 Costello diagrams (Figures 4 and 5)

The observation of these diagrams showed results similar to relative Index. Most of the predators seemed opportunistic feeders, the three categories being found in their diet. However percentages of each category fluctuated according to the predator.

For many predators, fish occurred very frequently. It was the main prey for swordfish (except in cruise2), whaoo and bigeye, respectively. It was a secondary diet for the yellowfin and albacore. Some Istiophorids seemed to have a specialized diet, feeding preferentially on fish.

Molluscs were never dominant or they were the main prey except for some swordfish individuals caught during the cruise 2 (northern part of the sampled region). They were rarely found in the stomach content of Istiophorids, wahoo and lancetfish, but some Molluscs were commonly eaten by yellowfin tuna and albacore.

Crustaceans are the main preys for albacore tuna and lancetfish and some yellowfin tuna caught during cruises 3 and 5. It is a rare prey for Istiophorids and whaoo, but a more generalized prey for bigeye tuna.

We observed differences in the diet of the swordfish according to the region. In the northern part molluscs were the main preys, in the southern one fish was dominant.

Table 5 summarizes these results.

3.3 Degree of repletion

The filling rate of the stomach content was low (Tables 3 and 4) for all predators. The lowest value was found for albacore tuna (0.1%). It increased to 0.5%-0.7% for Istiophorids and swordfish. It reached the highest value (0.9%) for the stomachs of Alepisaurus ferox.

3.4 Trawl catch

Among the 24 tows, 33 families and 68 species of fish have been found. In the two zones, the main families were: Myctophidae (64.1% in number) with genus Bolinichttys, Ceratoscolepus, Lampanictus, Llepidophanes and Notolychnus, Gonostomatidae (23,5%) with genus Cyclothone, Phosichthyidae (6%) with genus Vinciguerria, Sternoptychidae (1,5%) with genus Argyropelecus and Paralepididae (1,4%) with genus Lestidiops. Diretmidae, Evermanellidae, Gempylidae and Astronesthidae were present with few individuals.

Most of species were mesopelagic, living between 100 and 500 m depth. Gonostomatidae were found around 500 m depth (75% of the catch of this species) while Myctophiidae were caught between 100 m and 500 m. Other species were widely distributed between these layers. The families of Gonostomatidae, Sternoptychidae and Phosichthyidae were most abundant in the net contents of the cruise 2, while Myctophiidae and Paralepididae were equally distributed between the samples.

295 4. DISCUSSION

These preliminary results are a first analysis in an on-going research on trophic and foraging ecology of large pelagic predators in deep-sea ecosystems.

Examination and identification of the preys is a difficult task, especially if the stomach content is partially or fully digested. However, preys items identification to the lowest possible taxon is necessary to understand interactions between functional groups of preys and predators. This study deals with three cruises only, and the main problem was the heterogeneous sampling of predators. Therefore, comparison of diet among predators and between zones was difficult.

Like other studies focused on the diet of fish caught by long-lines, degree of repletion is low (never above 1%). It may be related to the fact that predators that bait are hungry ones (Bard, 2001; Bertrand et al., 2002).

At this stage, observations made in the Eastern Central Atlantic show that Istiophorids and Thunnidae are eating on a large number of preys, fish and crustaceans being the main items. The diet of swordfish shows regional differences. The molluscs are dominant among the prey in the north zone, and fish in the south zone. Lancetfish, which shows like tuna and swordfish, large vertical movements in the water column, eat on crustaceans and fish. Our results are different from other studies that showed that tuna caught by purse seiners in the Gulf of Guineawere feeding on single-species concentrations of Cubiceps pauciradiatus (Bard et al., 2002), or Vinciguerria nimbaria (Lebourges- Dhaussy et al., 2000; Ménard et al., 2000), or on Natosquilla investigatoris in the West Equatorial Indian Ocean around Seychelles (Potier et al., 2001 ; Potier et al., 2002). Such difference is linked to different behaviour among predators searching food at the surface and predators searching food in depth.

Micronekton organisms are potential preys for many pelagic predators. In fresh food examined, Phosichthyidae were rare while they have been found in the tows. On the other hand, Myctophidae and predators of this mesopelagic fish seem to be abundant in the diet (Table 2). However, fast swimming fish may avoid the net and give a false picture of micronekton composition. Therefore, comparisons between zones, stomach contents and trawling composition is difficult. Nevertheless, we observed some similarity between the two studies (presence of Myctophidae, Gempylidae and Paralepididae).

Further studies must be performed before to be able to give a clear view of the diet of large pelagic predators and their relations with micronekton.

5. ACKNOWLEDGMENTS

Great appreciation is expressed to O. Maury and P. Dewals (IRD-SFA Seychelles) for their work on board R.V. Shoyo-Maru and collaboration for the studies. We also thank captain and crew of Shoyo-Maru.

REFERENCES

BARD, F.X. 2001. Apparent effect of stomach repletion on catchability of large tunas to longline gear. Comparaison with other fishing gear. Col .Vol. Sci. Pap. ICCAT, Vol. 52; 452-465.

BARD, F.X., B. Kouamé et A Hervé. 2002. Schools of large yellowfin (Thunnus albacares) concentrated by foraging activity on a monospecific layer of Cubiceps pauciradiatus, observed in the eastern tropical Atlantic. Col .Vol. Sci. Pap. ICCAT, Vol. 54; 33-41.

296 BERTRAND, A., F.X. Bard and E. Josse. 2002. Tuna food habits related to the micronekton distribution in French Polynesia. Marine Bio logy, Vol. 140; 1023-1037.

CORTÉS E. 1997. A critical review of methods of studying fish feeding based on analysis of stomach contents : application to elasmobranch fishes. Can. J. Fish. Aquat. Sci., Vol. 54; 726-738.

COSTELLO, M.J. 1990. Predator feeding strategy and prey importance : a new graphical analysis. J. Fish. Biol., Vol. 36; 261-263.

HANSON, S. 1998. Methods of studying fish feeding: a comment. Can. J. Fish.Aquat. Sci., Vol. 55; 2706-2707.

LEBOURGES-DHAUSSY, A., E. Marchal, C. Menkès, A. Champalbert et B. Biessy. 2000. Vinciguerria nimbata (micronekton) environment and tuna: their relationships in the Estern Tropical Atlantic. Oceanologica Acta, Vol. 23 (4); 515-528.

MARSAC, F., 1999. THETIS, a new research program on tuna populations proposed by IRD in the Atlantic and Indian Oceans. 4th session of the Indian Ocean Tuna Commission, Kyoto, Japan, 13- 16 December 1999 IOTC/99/SC/10.

MÉNARD, F., B. Stéquer, A Rubin, M. Herrera et E. Marchal. 2000. Food consumption of tuna in the Equatorial Atlantic Ocean : FAD-associated versus unassociated schools. Aquatic Living Resources, Vol. 13; 233-240.

PINKAS, L., M.S. Oliphant et I.L.V. Iverson. 1971. Food habits of albacore, bluefin tuna and bonito in California waters. Calif. Fish Game, Vol. 152; 1-105.

POTIER, M., R. Sabatié, F. Ménard et F. Marsac. 2001. Preliminary results of tuna diet studies in the West equatorial Indian Ocean. 3th session of the Indian Ocean Tuna Commission, Mahé, Seychelles, 19-27 June 2001, IOTC/01/SC/.

POTIER, M., F.X. Bard, R. Sabatié, F. Ménard et F. Marsac. 2002. On-going research on trophic ecology of tuna and sworfish in equatorial ecosystems of the Atlantic and Indian Oceans. Indian Ocean Tuna Commission, Shanghai, Chine , 3-11 June 2002, GTTT/ WPTT/02/24.

297 Table 1.- Number of Stomachs collected, according to the species, during cruises on board the Shoyo-Maru

) A ) K A P ) H ( ) ) i M F ) a ) S ) W r H S ( T U ) O M i F ) ) a ) A ) r R E L W ( U Y T B h L ( ( O d ( o T L i B E L G ( r s ( n A s n W a s B A m P ( e u l e ( ( ( s a s S r a n x g d n ( o s a k u i ic s a a e o l b a s c u g s c c r f l lb c u s n e p a i i m a ia u s f a r e u r a e d iu lb b l l s s s s ig a a a b u u l b a o l g u u r r u n y a h r r r g s s c e u tu tu o a c c r s o u u s o s a L p p h i a t n n u d a e s a a p a i n n n n u n t i A r r o k h c p T t t i a u u u e io a e e t a ip c h h h s r r le O T T Is M X A T T T P P T A T cruise2 1 4 1 13 2 1 9 31 cruise 314838366610 1 166 cruise5131 21144 11340 total27948987231611123137

Table 2.- Preliminary list of fish families found in the stomach contents collected in Eastern Central Atlantic (october-december 2000). In bold, the most abundant families.

Fishes Molluscs Crustaceans

Myctophidae Cephalopoda decapoda Amphipoda Gempylydae Onychoteuthidae Phrosinidae Alepisauridae Ommastrephidae Hyperidae Paralepididae Cephalopoda octopoda Decapoda caridae Scopelarchidae Bolitaenidae Exocoetidae Argonautidae Bramidae Anoplogasteridae Notosudidae Scopelarchidae Trichiuridae Evermanellidae Diodontidae Tetraodontidae Ostraciidae Echeneidae Scombridae Microstomatidae

298

Table 3.- Stomach contents and relative importance of each item for cruise 2. %O : percent frequency of occurrence ; %N: percent by number ; %W: percent by weight : %IRI : percent of Index of Relative Importance: IRE : average percent index of repletion (weight stomach content reconstituted /wet weight of fish) : Wa ; average weight of predator. (*) removed of the analysis

CRUISE 2 %O %N %W %IRI IRE (n=1) (Wa=19,2kg) Istiophoridae (IST) * Fishes 100.00 77.78 90.60 84.19 Molluscs 100.00 22.22 9.40 15.81 0.828 Crustaceans 100.00 0.00 0.00 0.00 (n=4) (Wa=31,2kg) Xiphiidae (SWO) SWO SWO SWO Fishes 50.00 25.00 37.79 40.71 Molluscs 33.33 12.50 61.54 32.00 0.568 Crustaceans 33.33 62.50 0.67 27.30 (n=1) (Wa=27,3kg) A. solandri (WHA) * Fishes 100.00 100.00 43.51 100.00 Molluscs 0.00 0.00 0.00 0.00 0.011 Crustaceans 0.00 0.00 56.49 0.00 (n=13) (Wa=30,3kg) T.obsesus (BET) Fishes 92.31 67.51 86.72 83.48 Molluscs 69.23 10.66 12.21 9.28 0.583 Crustaceans 53.85 21.83 1.08 7.23 (n= 2) (Wa=20,0kg) T.alalunga (ALB) Fishes 100.00 40.24 57.28 48.76 Molluscs 100.00 12.20 6.68 9.44 0.855 Crustaceans 100.00 47.56 36.04 41.80 (n=9) (Wa=3,5kg) A. ferox (ALE) Fishes 66.67 15.73 55.27 45.53 Molluscs 22.22 13.48 31.61 9.64 0.986 Crustaceans 55.56 70.79 13.12 44.83

Table 4.- Stomach contents and relative importance of each item for cruises 3 and 5. %O : percent frequency of occurrence ; %N: percent by number ; %W: percent by weight : %IRI : percent of Index of Relative Importance: IRE : average percent index of repletion (weight stomach content reconstituted /wet weight of fish) : Wa ; mean of weight.

CRUISES 3 and 5 %O %N %W %IRI IRE (n=47) (WA=33,2kg) Istiophoridae (IST) Fishes 23.4 67.7 91.2 75.3 Molluscs 29.8 32.0 8.8 24.6 0.557 Crustaceans 2.1 0.3 0.0 0.0 (n=5) (Wa=39,9kg) Xiphiidae (SWO) Fishes 100.0 91.8 94.1 96.0 Molluscs 60.0 4.9 5.6 3.3 0.758 Crustaceans 40.0 3.3 0.2 0.7 (n=7) (Wa=18,9kg) A. solandri (WHA) Fishes 71.4 73.7 88.4 91.4 Molluscs 28.6 26.3 11.6 8.6 0.183 Crustaceans 0.0 0.0 0.0 0.0 (n=7) (Wa=52,7kg) T.albacares (YFT) Fishes 100.0 15.4 72.5 62.2 Molluscs 57.1 17.4 20.8 15.5 0.306 Crustaceans 42.9 67.1 6.7 22.4 (n=10) (Wa=34,3kg) T.obsesus (BET) Fishes 90.0 51.9 76.4 69.8 Molluscs 80.0 15.0 19.3 16.6 0.355 Crustaceans 60.0 33.1 4.3 13.6 (n=14) (Wa=29,7kg) T.alalunga (ALB) Fishes 64.3 18.3 18.1 15.7 Molluscs 64.3 18.3 51.4 30.1 0.111 Crustaceans 85.7 63.5 30.6 54.2 (n=14) (Wa=4,5kg) A. ferox (ALE) Fishes 35.7 13.5 72.7 30.7 Molluscs 28.6 4.7 5.6 3.0 0.887 Crustaceans 64.3 81.8 21.7 66.4

299 Table 5.- Stomach contents and trophic behaviour

IST SWOWHA YFT BET ALB ALE Specialization Cruise 2 S O O S Cruise 3+5 S O O S O O S Dominant prey Cruise 2 M F C C Cruise 3+5 F F F C F C C S: Specialized O: Opportunistic F: Fish M: Molluscs C: crustaceans

Fig. 1.- Location of long lines sets and IKMT nets performed during the three trips on board the R/V Shoyu-Maru in the Eastern Central Atlantic from october to december 2000

300 percent of 100 idi %O 90 %N 80 %W

70 60 50 40

30 20 10

0 Istiophoridae Xiphiidae A. solandri T.obesus T.alalunga A. ferox

s s s s s s s e cs ns es n e cs n cs ns e cs s a h s s a h s u e ish u u e is lu Fish ll c Fis llusc F ll Fishes Fishes ll F ta Mo Mo stacea Mo stacea Mollusc Mo stac Mol u ru Crus Cr C Crustaceans Cru Crustaceans

Fig. 2.- Importance of the three groups of preys according to predators diets. Cruises 2. Distribution in %occurence, %number and %weight.

percent of indices 100 %O 90 %N 80 %W 70 60 50 40 30 20

10

A. ferox 0 Istiophoridae Xiphiidae A. solandri T.albacares T.obesus T.alalunga

Fishes Fishes Fishes Fishes Fishes Fishes Fishes

Molluscs Molluscs Molluscs Molluscs Molluscs Molluscs Molluscs

Crustaceans Crustaceans Crustaceans Crustaceans Crustaceans Crustaceans Crustaceans

Fig. 3.- Importance of the three groups of preys according to predators diets. Cruises 3 and 5. Distribution in %occurence, %number and %weight.

301 %Abundance 100

90

80

C 70 F M

60 SWO BET 50 C LFT ALE 40 F 30 F C 20 F M M C M 10 M 0 0 102030405060708090100 %Occur r ence

Fig. 4.- Costello diagram. Distribution of preys taxa from different species caught during cruise 2, in october 2000. (F), fish; (M), molluscs ; (C), crustaceans

%Abundanc 100

90 F C 80 F 70 IST F C C SWO 60 F WHA 50 YFT BET 40 LFT M C ALE 30 M M M 20 M F F F 10 C M C M M C 0 0102030405060708090100%Occurrenc

Fig. 5.- Costello diagram. Distribution of preys taxa from different species caught during cruises 3 and 5 respectively in november and december 2000. (F), fish; (M), molluscs; (C), crustaceans

302