femelles étaient le Lepidopus caudatus, le Scomber japonicus et le Trachurus picturatus, que l’on a détecté dans plus de 50 % des contenus stomacaux de chaque sexe. Toutefois, il semble y avoir une différence notable entre la principale proie préférée par chaque sexe, le L. caudatus chez les femelles et le Capros aper chez les mâles. Pour ce qui est des céphalopodes, l’Ommastrephes bartramii prédominait chez les femelles (22 % des contenus stomacaux), et l’Argonauta argo et l’Histioteutis dofleini (14 %) chez les mâles. Un G-test a servi à comparer la fréquence d’apparition des groupes de proies chez les deux sexes. Aucune différence significative n’a été observée dans l’alimentation entre les mâles et les femelles. Toutefois, la présence plus fréquente de céphalopodes à déplacement rapide, comme l’Ommastrephes bartramii et le Todarodes sagittatus dans l’alimentation des femelles, comme leur absence dans celle des mâles, pourrait indiquer quelque limitation physiologique et quelque différence de comportement entre les sexes. En fait, s’il existe des différences quant au choix de l’habitat des mâles et des femelles, il pourrait également y avoir des différences quant à leur disponibilité à la pêche de palangre.
RESUMEN
Este documento presenta algunos resultados sobre la dieta del pez espada, Xiphias gladius, en las aguas en torno a Azores. De los 82 estómagos examinados (58 hembras y 24 machos), el 11% estaban vacíos (9 estómagos). En cuanto a los otros 73, se compara entre los sexos la composición por presas y algunas de las peculiaridades biológicas de las especies de presas. En 51 hembras, se identificó un total de 11 especies de peces que contribuían al 65,5% del peso total del estómago. También se identificó un total de 15 especies de cefalópodos (34,4%). En 22 machos se identificó un total de 9 especies de peces (91,4% del peso total del estómago), así como 4 especies de cefalópodos (8,5%). Los teleósteos componían el grupo más importante de presas en el contenido estomacal, tanto de las hembras como de los machos. En términos de frecuencia de presencia de las especies de peces más importantes en la dieta de hembras y machos Lepidopus caudatus, Scomber japonicus y Trachurus picturatus, representaban un porcentaje superior al 50% del contenido estomacal de cada sexo. No obstante , parece existir una diferencia notable sobre la especie de presa preferente en cada sexo. L. caudatus, en hembras y Capros aper en los machos. Entre los cefalópodos, la especie más importante en las hembras era Ommastrephes bartramii, que estaba presente en el 22% del contenido estomacal, y en los machos Argonauta argo y Histioteuthis dofleini (14%). Se empleó un G-test para establecer una comparación de la ocurrencia de grupos presa entre los sexos. No se encontraron diferencias significativas en la dieta entre machos y hembras. Sin embargo, la mayor ocurrencia de especies de cefalópodos de natación rápida, como Ommastrephes bartramii y Todarodes sagittatus en la dieta de las hembras, y su ausencia en la dieta de los machos, podría indicar la existencia de algunas limitaciones fisiológicas y diferencias de comportamiento entre ambos sexos. De hecho, si hay diferencias entre machos y hembras en cuanto a la selección del hábitat, su disponibilidad a la pesquería de palangre de superficie también podría ser distinta. Keywords: Swordfish, Sex, Diet, Behaviour, Fishery
Introduction
The swordfish is a very aggressive and voracious mesopelagic teleost (Palko et al., 1981; Chalabi & Ifrene, 1993). It is an opportunistic predator feeding mainly on pelagic schooling fishes (Tibbo et al., 1961) as well in schooling cephalopods (Guerra et al., 1993). This species also shows cannibalism during the larval and post-larval stages (Arata, 1954). The swordfish presents some external specialised features according to its feeding habits, namely the shape of the sword (Tibbo et al., 1961; Scott & Tibbo, 1968; Toll & Hess, 1981), the reduced size of the lower mandible (McGowan, 1988) and the presence of large eyes (Carey & Robinson, 1981). Swordfish’s diet throughout their geographical range has been described by numerous authors, e.g. Tibbo et al. (1961), Scott and Tibbo (1968), Scott and Tibbo (1974), Toll and Hess (1981), Hess and Toll (1981), Stillwell and Kohler (1985), Azevedo (1990), Moreira (1990), Chalabi and Ifrene (1993), Guerra et al. (1993), Clarke et al. (1995), Hernández-Garcia (1995), Relini et al. (1995), Barreto et al. (1996), among others. No differences were found between the diets of female and male (Toll & Hess, 1981, Stillwell & Kohler, 1985, Guerra et al., 1993; Barreto et al., 1996). However, there are few studies that compare the ecology of prey and predator in each sex. In this sense, the main objective of this paper is to analyse the prey species composition in the diet of each sex, from a sample taken in Azores area. In addition, the existence of a relationship between prey ecology and swordfish individual behaviour was also verified.
Material and methods
The stomach contents of 82 swordfish were analysed. From these 58 were females (86- 233 cm Ljfl) and 24 were males (99-174 cm Ljfl) (Figure 1). The sample was taken during the commercial landings of the Azores longline fleet. For each individual sampled, size, weight and sex were registered along with the fishery data (gear, month and area if possible). Stomachs were removed immediately after sampling. After being deep frozen, the contents of each stomach were thawed out and laboratory proceedings were performed according to Toll and Hess (1981) and Herrán (1988). For each stomach, the basic contents (fish, crustaceans, cephalopod and unidentified items) were sorted, fixed in 10% formalin and transferred to 70% ethyl alcohol for storage. Prey items were identified to the lowest possible taxonomic category. Fish were identified from otoliths and bones using keys provided in Smale et al. (1995) and author’s collection. Scomber sp. that showed hook marks and/or occurred quasi intact in the stomach contents were assumed to be bait and rejected for analysis. Lower beaks were used as the primary means for classification of cephalopods and beak identity was established by available keys provided in Clarke (1962;1986), Pérez-Gandaras (1986), Voss (1969;1985), Wolff (1982) and author’s collection. In some cases, upper beaks, the known geographical distribution and the existence of monotypism were used (Clarke, 1986). The otolith length (OL) and the lower rostral length (LRL) were measured by stereoscopic microscope or digital calliper. The weights (g) of the teleosts from which otoliths came were then estimated from OL’s by using relationships provided in Isidro (1990), Moreira (1990), Clarke et al. (1995) and Smale et al. (1995). The weights (g) of the cephalopods from which lower beaks came where then estimated from LRL’s by using relationships published in Clarke (1962; 1986). Nematodes were found in the majority of the stomachs and in some of them, in large quantities, but these were assumed to be parasites and were not considered as prey.
The following indices were used to quantify the diet in each sex: -Frequency of occurrence as the number of stomachs where a certain prey item occurred, expressed as percentage to the total number of stomachs (f%) (Hyslop, 1980). -Weight percentage as the wet weight of a particular prey item relative to the total weight of all prey, in the whole sample (w%) (Herrán, 1988) -Relative frequency (in number) as the number of a certain prey item expressed as percentage to the total number of prey, in the whole sample (n%) (Herrán, 1988).
A comparison of the diet of each sex was made applying the G-test to the frequency of occurrence of the prey groups. The statistic G was corrected by Williams’s correction factor (Gadq) (Zar, 1984). To analyse the prey importance in the diet of each sex, the prey alimentary factor, Q (*) (Hureau, 1970) was used according to Geistedoerfer prey classification (Geistedoerfer, 1975). This author presented a new proposal of the Hureau prey grouping, introducing the prey frequency of occurrence in prey classification.
(*) Q=(%n * %w) (Hureau, 1970)
Results
From the 82 stomachs examined, 11% were empty (9 stomachs). In the remaining 73, a total of 11 fish species, belonging to 11 families and 11 genera, was identified, which corresponded to 467 specimens. A total of 15 cephalopod species belonging to 13 families and 17 genera was identified, corresponding to 83 specimens. One Penaeidae family was also identified in female’s stomach contents, which corresponded to 1 specimen. Due to the low crustacean representativity in the stomach contents, this prey group was not considered in the present analysis (Table I and II). In the 51 females observed, a total of 11 fish species was identified (256 specimens) and contributed to 65.5% of the total stomach weight. A total of 15 cephalopod species was also identified (65) and contributed to 34.4% of the total stomach weight. In 22 males, a total of 9 fish species was identified (211 specimens) and contributed to 91.4% of the total stomach weight. Four cephalopod species (18) were also identified, contributing to 8.5% of the total stomach weight.
Figure 2 and 3 show the frequency of occurrence of teleosts prey and the respective length interval found in female and male’s diet, respectively. The majority of identified species were common on both sexes, occurring in a wide length interval. L. caudatus (Silver scabbard-fish), S. japonicus (Spanish mackerel) and T. picturatus (Horse mackerel) were the only species that occurred in more than 50% of stomach contents, in each sex. C. aper (Boar-fish), D. argenteus and Myctophidae (lanterfishes), small species, showed a higher occurrence in male’s stomach contents than on females.
Figure 4 and 5 show the frequency of occurrence of the common cephalopod preys in the diet of both sexes and the respective length interval found in female and male’s diet, respectively. Histioteuthis was presents with a higher occurrence in males’s stomach contents, being H. dofleini the most important species identified. In contrast, Ommastrephidae was present with a higher occurrence in female’s diet.
Table III shows the frequency of occurrence and the respective length interval of the cephalopod species identified only in female’s stomach contents. Among the identified species, O. bartramii (Ommastrephidae), was the most important species, occurring in 22% of female’s stomach contents and in a wide length interval (86-205 cm). One individual belonging to the genus Discoteuthis (Cycloteuthidae) was identified in a 99 cm male. This genus was absent in females.
In order to apply the G-test, null occurrence and less than 5 stomach/prey were put together in a more generic group of prey items. Thus, fishes were grouped in “Other fishes” and cephalopods were grouped in “Other squids” (Table IV). No significant differences were found in the diet between males and females 2 (Gadq Table V presents the Geistedoerfer prey classification for each sex. Table VI and VII (Appendix) present the prey relative frequency in number and weight percentage index, respectively, in each sex. Comparing the common species in the diet of each sex, L. caudatus was the principal preferential prey (Q>100 and f%>30%) in females and secondary frequent (10 Discussion The knowlegde of the prey type in a particular predator is a basic aspect that should be considered to better understand the anatomical, physiological and behavioural adaptations of the predator as well as a way to establish the trophic link between predator/prey (Herrán, 1988). Toll and Hess (1981) and Zavala-Camin (1987) referred that information on stomach contents could supplement or even refine, existing knowledge of the biology of both predator and prey. In this sense, possible changes in the distribution and abundance of marine resources could have consequences in changing feeding habits of an opportunistic feeder like swordfish (Stillwell & Kohler, 1985). Since the last decade, there seems to be a change in the most important prey species of the swordfish diet, in a similar geographic area. Based on a sample taken in the Atlantic NE, between Azores and Madeira Islands and Galicean coast (33º-50ºN) during 1990, Guerra et al. (1993) noted the great importance of Sthenoteuthis pteropus (Ommastrephidae) in the swordfish stomach contents. In a sample taken in Azores EEZ during 1992-93, Clarke et al. (1995) noted the importance of O. bartramii in the swordfish stomach contents, with 24% of the total estimated weight, followed by L. caudatus, with 17%. In a sample taken in Azores EEZ during 1993-95 (Simões, unpublished) and using the combined method of Pinkas et al. (1971) (IRI), classified by Rosecchi prey scale (Rosecchi, 1988), the most important species identified in swordfish’s diet (both sexes) was L. caudatus. This change in the most important prey species might be explained by the higher abundance of L. caudatus in the Azores fishing area during the last years (Silva et al., 1994; Silva & Menezes, 1995). The presence of L. caudatus in the swordfish diet could explain the opportunistic behaviour of this species, which prey upon the most available prey. The present analysis was based mainly on small fishes. In this sense, the considerations undermentioned were limited by this fact. The limitation of the c2 distribution to low prey frequencies of occurrence did not allow the diagnosis of differences on species prey composition in diet between females and males. Thus, some ecological features of each prey species should be analysed in order to detect possible differences on swordfish individual behaviour. Teleosts were the most important group in the swordfish stomach contents in both sexes. The majority of the species found were common in female and male’s diet, being L. caudatus, S. japonicus and T. picturatus the most important species in terms of frequency of occurrence. Nevertheless, it seems to exist a notorious difference between the principal preferential prey species in each sex: L. caudatus in females and C. aper in males. L. caudatus is a very aggressive and extremely voracious bentopelagic species, reaching considerable sizes (205 cm SL) and can attack larger sizes prey (Bauchot & Pras, 1980; Whitehead et al., 1986). C. aper is a gregarious epipelagic species reaching smaller sizes, usually 5-13 cm SL, occurring between depths of 40-600 meters (Whitehead et al., 1986). The importance of C. aper in male’s diet might show an intense feeding activity in the uppermost layers of water. The presence of L. caudatus in male’s stomach contents could be explained by their occasional arising in coastal zones, associated with upwelling phenomena, where they appear in dense aggregations (Whitehead et al., 1986; Fisher et al., 1987). Among the cephalopods species identified, T. sagittatus, O. bartramii and Histioteuthis spp. were especially noted. The daily vertical migrations of swordfish are similar to T. sagittatus and O. bartramii, both powerful and muscular swimmers (Clarke, 1986; Guerra et al., 1993). T. sagittatus is a neritic and oceanic species occurring from the surface to depths of 2500 meters (Guerra, 1992). O. bartramii is an epipelagic and mesopelagic species, reaching depths of 1500 meters, showing important vertical and horizontal migrations and could form aggregations of some density (Guerra, 1992). According to Wormuth (1976), this species is a schooling squid until about 50 cm ML when it becomes solitary. This species was the most important cephalopod species in female’s diet. The smallest O. bartramii found, was identified in the smallest female (86 cm, age 0) and the largest one was found in a 191 cm female (age 6) (Simões, unpublished). This might indicate some ontogenetic changes in prey selection as described by Yabe et al. (1959 in Toll & Hess, 1981) for the Pacific swordfish. The presence of both species in female’s diet indicates that swimming ability is not a limiting factor in the selection of this kind of prey (Toll & Hess, 1981; Guerra et al., 1993). The absence of the cephalopod species above mentioned in male’s stomach contents could indicate differences in feeding behaviour possibly due to specific physiological limitations. Nevertheless, the presence of Ommastrephidae in adult males should not be neglected. The inherent problem with the upper beaks identification which can lead to mistakes in the identification of cephalopod families (Clarke, 1962) should be considered in future studies. The Histioteuthis species are predominantly mesopelagic but can occur both in epipelagic and bathypelagic zones (Voss, 1969). According to this author, the Histioteuthis vertical distribution is intimately related with temperature. This genus seems to have more importance in the stomach contents of males. H. dofleini (the most common species in the sample) occurs between depths of 100-700 meters or even, 800 meters (Voss, 1969). H. reversa appears to range from surface waters to approximately 1000 meters, and in greatest abundance in proximity to landmasses or oceanic ridges (Voss, 1969). H. elongata appears to range between 500-1000 meters (Guerra, 1992). In the present study, H. reversa was found in a 116 cm male and 120 cm female (same age of both sexes, 1 year) and H. elongata was found in a 182 cm female (age 5). According to Voss et al. (1998), the H. elongata is the mature stage of H. reversa, suggesting that this species might show ontogenetic vertical distribution. In a mature female (174 cm), an unusual occurrence of the genus Grimpoteuthis, a benthic octopod, was found. Voss (1953 in Toll & Hess, 1981) also found this genus in sailfish (Istiophorus albicans). Scott and Tibbo (1968) reported the occurrence of another octopod, Bathypolypus arcticus, a benthic inhabitant of the continental shelf. Numerous abiotic (temperature, oxygen, salinity, transparency, light intensity, currents) and biotic factors (presence of conspecifics, prey and predators) characterise the pelagic environment. Fish are able to detect these characteristics and consequently react to their variation by horizontal or vertical displacement (Fréon & Misund, 1999). Habitat selection is an important behavioural function for adult fish especially in feeding, reaction to predator, agonistics and sexual behaviour (Huntingford, 1986). The selection of habitat varies with stages of the life history. In swordfish it seems that feeding and spawning often take place in different areas. According to a circadian or seasonal rhythmicity there is a change in habitat which results in migrations within and among areas. Mejuto and Hoey (1991) referred the existence of a relationship between temperature and swordfish size, where the smaller individuals are more dependent than the larger ones. The presence of a sexual dimorphic growth where males reach smaller sizes than females could have consequences on a more restricted male’s horizontal and vertical distribution than females. The thermal dependence of males could be reflected in the predominance of H. dofleini in their stomach contents, a species know to prefer higher temperatures (Voss, 1969). The large swordfish predominantly females showed a great tolerance on a wide range of temperature, light, pressure, dissolved oxygen and salinity, during the daily vertical migrations (Carey & Robinson, 1981). This could result in a wider habitat. The cephalopod species found in female’s stomach contents comprise epi- meso- and bathypelagic distribution (Guerra et al., 1993). This could indicate that females could feed in the uppermost layers of water as well as in the deeper ones. Similarly, the presence of Grimpoteuthis in a mature female could confirm the great capacity of large individuals moved and stays in higher depths as was described by Carey and Robinson (1981). According to Mejuto and Hoey (1991), due to thermal dependence, smaller individuals are less active than bigger ones. The recognised versatility of large swordfish in the environment (Holland, pers. comm.) could allow an intense feeding activity through the fast swimmers species like O. bartramii and T. sagittatus compared to the small swordfish, during daily vertical migration. Mejuto et al. (1998) referred that “the migration of males, in terms of probability, would be somewhat more restrictive possibly due to combination of limiting factors such as temperature of water masses, the individual biomass of their bodies and/or physiological conditions such as reproduction. In contrast, the migration of females is usually more broad- ranging”. If, in fact, females and males have a different habitat selection, then differences on the availability to the surface longline fishery could be expected. Taking into account that male’s vertical distribution could be narrower, its vulnerability to the surface longline might be higher than females. Fréon and Misund (1999) referred that habitat selection and migration govern the availability of the fish in both the horizontal and vertical dimension and therefore the catch rates. Thus, further research should be carried out, on the potential differences at the individual level, in order to better understand changes in the population. As suggested by the Swordfish Working Group in ICCAT, developing sex-specific VPA (ICCAT, 1999) could be a first step in detecting behavioural differences between sexes. Acknowledgments Thanks to Department of Oceanography and Fisheries of the University of Azores (DOP/UAC), for their support in the development of this study. Special thanks to Dr. Angel Guerra (Instituto de Investigaciones Mariñas, Vigo, Spain) for helping in the cephalopods beaks identification and revision of the manuscript. 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Pap., XXVI(2): 582-583 Table I: Teleost prey species identified in swordfish stomach contents Family Genus Species Prey (nº)* Otoliths (nº) Berycidae Beryx B. splendens 2 3 Caproidae Capros C.aper 153 2 Carangidae Trachurus T.picturatus 71 4 Diretmidae Diretmus D. argenteus 81 126 Gadidae Micromesistius M. poutassou 2 2 Myctophidae 44 67 Myctophum M. punctatum 5 7 Macroramphosidae Macroramphosus M.scolopax 2 Scombridae Scomber S. japonicus 29 Sparidae Pagellus P. bogaraveo 31 46 Trichiuridae Lepidopus L.caudatus 46 7 Scorpinidae Helicolenus H. dactylopterus 1 1 Not identified 4 14 Total 11 10 467 279 (*): Total number of fishes: all the specimens observed during sampling plus the specimens represented by their otoliths Table II: Cephalopod prey species identified in swordfish stomach contents Family Genus Species Prey (nº) Beaks (nº) Alloposidae Haliphron H. atlanticus 3 5 Argonautidae Argonauta A. argo 10 12 Ocythoidae Ocythoe O. tuberculata 6 10 Stauroteuthidae Grimpoteuthis ? Grimpoteuthis ? sp. 1 2 Chiroteuthis C. verany 1 1 Chiroteuthidae Chiroteuthis sp. 2 3(1U) Grimalditeuthis Grimalditeuthis sp. 1 2 Taonius T.pavo 3 4 Cranchiidae Teuthowenia T. megalops 1 2 Cranchia C. scabra 1 2 Cycloteuthidae Discoteuthis Discoteuthis sp. 1 2 H. dofleini1 10 15(2U) Histioteuthidae Histioteuthis Histioteuthis sp. B2 2 4 H. reversa 1 2 H. elongata 1 1 H.? aff. reversa 1 1U Lepidoteuthidae Lepidoteuthis L. grimaldi 1 2 Ommastrephidae 8 8U Ommastrephes O. bartramii 17 31 Todarodes T. sagittatus 5 9 Onychoteuthidae Onychoteuthis O. ? aff. banskii 1 2 Chaunoteuthis- stage3 1 2 Pholidoteuthidae Pholidoteuthis P. boschmai 3 5 Loliginidae Loligo L. forbesi 2 4 Unkonw Unkonw 1 2 Not identified 3 3U Total 18 22 83 136 Legend: U letter means upper beak Notes: (1)Histioteuthis dofleini is the same as H. arcturi (Robson 1948) (Voss et al., 1998). (2)The genus Histioteuthis has two types of lower beak: A and B (Clarke, 1996). (3)Chaunoteuthis is a not valid genus because it represents unhealthy Onychoteuthidae individuals (Kubodera et al., 1998). Table III: Cephalopods prey species found only in female’s diet Taxa Frequency of occurrence Length range (%f) (Ljfl, cm) O.tuberculata 8 124-192 Grimpoteuthis ?sp. 2 174 C.veranyi 2 145 Chiroteuthis spp. 4 151-174 C.scabra 2 205 T.megalops 2 121 T.pavo 6 111-155 Grimalditeuthis sp. 2 149 L.grimaldi 2 155 O.bartramii 22 86-205 T.sagittatus 4 155-182 O.banskii 2 205 P.boschmai 6 120-155 L.forbesi 4 126-151 Table IV: Number of stomachs containing each prey groups in females and males Sex Lepidopus Trachurus Scomber Capros Other Histioteuthis Octopoda Other Fishes Squids Female 26 26 25 15 13 6 8 18 Male 12 11 11 9 7 7 5 4 Table V:Geistedoerfer prey classification by sex Taxa Females Males Lepidopus PP SF Scomber SF SF Trachurus SF SF Capros SF PP Ommastrephes SF Pagellus SF PO Diretmus SA SF Todarodes SA Histioteuthis C1ª SF Myctophidae C2ª SA Legend: PP: Principal preferential prey; PO: Principal occasional prey; SF: Secondary frequent prey; SA: Secondary accessory prey; C1ª: First order complemental prey; C2ª: Second order complemental prey 16 14 12 10 Females 8 Males 6 4 Number of swordfish sampled 2 0 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 Ljfl (cm) Figure 1: Length distribution (10 cm interval) of swordfish sampled in each sex 60 240 50 200 40 160 30 120 20 80 10 40 0 0 Figure 2: Teleost prey frequency of occurrence and the respective length interval in females 60 240 50 200 40 160 30 120 20 80 10 40 0 0 Figure 3: Teleost prey frequency of occurrence and the respective length interval in males 35 240 30 200 25 160 20 120 15 80 10 40 5 0 0 Figure 4: Cephalopods prey frequency of occurrence and the respective length interval in females 35 240 30 200 25 160 20 120 15 80 10 40 5 0 0 Figure 5: Cephalopods prey frequency of occurrence and the respective length interval in males APPENDIX Table VI: Relative frequency, in number (%n) by sex Taxa Females Males Beryx 0.3 0.4 Capros 22.0 35.8 Trachurus 12.7 13.1 Diretmus 13.0 17.0 Micromesistius 0.3 0.4 Mictophidae 5.6 11.4 Myctophum 0.3 1.7 Macroramphosus 0.6 Scomber 6.5 3.5 Pagellus 6.5 4.4 Lepidopus 11.2 4.4 Helicolenus 0.3 Haliphron 0.3 0.9 Argonauta 1.9 1.7 Ocythoe 1.9 Grimpoteuthis 0.3 Chiroteuthis 0.9 Cranchia 0.3 Teuthowenia 0.3 Taonius 0.9 Discoteuthis 0.4 Grimalditeuthis 0.3 Histioteuthis 2.2 3.5 Lepidoteuthis 0.3 Ommastrephes 5.3 Todarodes 1.6 Onychoteuthis 0.6 Pholidoteuthis 0.9 Loligo 0.6 Table VII: Weight percentage (%w) by sex Taxa Females Males Beryx 0.2 0.2 Capros 1.6 5.7 Trachurus 4.4 4.8 Diretmus 1.8 4.9 Micromesistius 0.1 0.4 Myctophidae 0.4 1.6 Myctophum 0.02 0.3 Macroramphosus 0.01 Scomber 13.4 16.7 Pagellus 11.3 23.3 Lepidopus 25.5 21.9 Chiroteuthis 0.2 Cranchia 0.2 Teuthowenia 0.3 Taonius 0.7 Histioteuthis 2.3 8.9 Ommastrephes 11.6 Todarodes 12.7 Onychoteuthis 1.1 Pholidoteuthis 5.3 Loligo 0.9