Lat. Am. J. Aquat. Res., 39(3): 449-460, 2011
DOI: 10.3856/vol39-issue3-fulltext-6

Research Article

 

Daily food intake of Kajikia audax (Philippi, 1887) off Cabo San Lucas, Gulf of California, Mexico

Tasa de consumo diario de alimento de Kajikia audax (Philippi, 1887) frente a Cabo San Lucas, golfo de California, México

 

Leonardo A. Abitia-Cárdenas¹, Felipe Galván-Magaña¹, Víctor H. Cruz-Escalona¹, Mark S. Peterson² & Jesús Rodríguez-Romero³

¹Centro Interdisciplinario de Ciencias Marinas, Instituto Politécnico Nacional (CICIMAR) P.O. Box 592, La Paz, B.C.S., México
²Department of Coastal Sciences, The University of Southern Mississippi 703 East Beach Drive, Ocean Springs, MS 39564, USA
³Centro de Investigaciones Biológicas del Noroeste (CIBNOR), Mar Bermejo 195 Col. Playa Palo de Santa Rita, La Paz, B.C.S., México

Dirección para correspondencia

---

ABSTRACT. The daily food intake rates of the striped marlin, Kajikia audax (Perciformes: Istiophoridae), were estimated using qualitative and quantitative analyses of their trophic spectrum. We analyzed the stomach contents of 505 striped marlin caught by the sport fishing fleet off Cabo San Lucas, Baja California Sur, Mexico, sampled from October 1987 through December 1989. The most important preys were chub mackerel (Scomber japonicus), California pilchard (Sardinops caeruleus), and jumbo squid (Dosidicus gigas); together these represented ~55% of the striped marlin diet. The daily food consumption was estimated to be 2 kg per day, or ~3.6% of the mean body weight of K. audax. The total biomass of the prey consumed by the striped marlin during the 27 months of sampling around Los Cabos was estimated at 24.8 ton, of which the chub mackerel represented ~29% (7.2 ton), California pilchard just under 16% (3.9 ton), and jumbo squid ~10% (2.5 ton). The feeding habits of K. audax are discussed in terms of the distribution of the epipelagic (neritic and oceanic zones), demersal, and benthic prey, confirming that striped marlin migrate vertically and horizontally in search of their food.

Keywords: billfish, striped marlin, diurnal variation, consumption, Cabo San Lucas, Gulf of California, Mexico.

---

RESUMEN. Se estimó la tasa de consumo diario de alimento del marlín rayado Kajikia audax (Perciformes: Istiophoridae), sobre la base de análisis cualitativos y cuantitativos de su espectro trófico. Se analizó el contenido estomacal de 505 ejemplares capturados por la flota deportiva frente a Cabo San Lucas, Baja California Sur, México muestreados de octubre 1987 a diciembre 1989. Las presas más importantes fueron la macarela del Pacífico (Scomber japonicus), sardina monterrey (Sardinops caeruleus) y calamar gigante (Dosidicus gigas), que en conjunto representaron aproximadamente el 55% de la dieta. La tasa de consumo de alimento fue estimado en 2 kg diarios, lo cual representó aproximadamente el 3,6% del peso corporal de K. audax. La biomasa total de presas consumidas por el marlín rayado durante los 27 meses muestreados en la zona de Los Cabos fue estimada en 24,8 ton, de las cuales la macarela del Pacífico representó alrededor del 29% (7,2 ton), la sardina monterrey poco menos del 16% (3,9 ton) y el calamar gigante aproximadamente el 10% (2,5 ton). Los hábitos alimentarios de K. audax se discutieron según la distribución de las presas epipelágicas (neríticas y oceánicas), demersales y bentónicas; lo cual confirmó la conducta migratoria (movimientos verticales y horizontales) del marlín rayado en busca de su alimento.

Palabras clave: picudos, marlín rayado, variación diurna, consumo, Cabo San Lucas, golfo de California, México.

---

INTRODUCTION

Istiophorid billfishes are highly migratory species that inhabit the tropical and subtropical, epipelagic waters of the world's oceans, a large, relatively homogeneous environment that lacks significant physical barriers and most species spawn over broad geographic regions during a protracted season (Nakamura, 1995). They are targeted by both recreational and commercial fisheries all over the world. Yet despite this, there still remain large gaps in our knowledge of the biology and ecology of these species. Particularly, striped marlin Kajikia audax (Philippi, 1887) supports an important commercial catch in several regions of the world, while also forming the basis of important recreational fishing in the United States, Mexico, Ecuador, New Zealand, East Africa and Australia (Domeier, 2006). This species is highly prized as food (sashimi and smoked and frozen filet) for the excellent quality of its flesh and the high ratio of usable meat to body weight (Sosa-Nishizaki, 1998).

Striped marlin in Mexican waters and particularly in Cabo San Lucas at the southern tip of the Baja California Peninsula forms the core of sport fishing. The southern Gulf of California is a migration zone for striped marlin (Squire & Suzuki, 1990; Abitia-Cárdenas et al., 1998), where fish longer than 200 cm postorbital length (modal PL) are feeding and storing energy in preparation for reproduction (Abitia-Cárdenas et al., 2002). Its larvae (2.8-30.5 mm total length) have been collected in near shore waters south of Los Cabos, suggesting that spawning occurs in the lower Gulf of California when water temperature is ≥ 27.0°C (González-Armas et al, 1999).

There are several general studies on the feeding habits of striped marlin in the Pacific Ocean (Hubbs & Wisner, 1953; De Silva, 1962; Evans & Wares, 1972; Eldrige & Wares, 1974; Abitia-Cárdenas et al., 1997, 1998). Abitia-Cárdenas et al. (2002) estimated seasonal total energy storage (kcal g^-1 wet weight) as well as energy storage in muscle and gonadal tissue of a limited number of female striped marlin from the Los Cabos region. However, there are no published estimates of their daily food consumption. An ecosystem approach to fisheries management requires an understanding of the impact of predatory fish on the most important prey species and that the measured rates of food consumption by apex predators lay the ground work for gaining insight into the role of predators in the food web of the marine ecosystem (Olson & Galván-Magaña, 2002). The goal of this study was to estimate the daily biomass consumption of the main prey species of striped marlin in the Los Cabos, Mexico area based on qualitative and quantitative analysis.

MATERIALS AND METHODS

Stomach samples were collected from the striped marlin catch by the sport fishing fleet, trolling with live bait or jigs in the area of Los Cabos (22°53'N, 109°54'W) from October 1987 through December 1989 (Fig. 1). In order to study the influence of the size of the fish, the data was grouped in 12 size classes (from 111-221 cm postorbital length) (Ponce-Diaz et al., 1991). The postorbital length (eye-fork length) and weight of each fish was measured and the stomach was preserved in formalin. Stomachs were weighed, food was removed, and the contents were weighed and stored according to the digested prey and its degree of digestion. Vertebral characteristics (e.g., number and position) were used to identify fish using taxonomic keys (Miller & Jorgensen, 1973) whereas, for undigested fish, we used (Miller & Lea, 1972; Allen & Robertson, 1994; Fischer et al., 1995). Crustaceans were identified using (Brusca, 1980; Fischer et al., 1995) and cephalopods were identified from the mandible (beaks) using (Wolff, 1982; Clarke, 1986).

Figure 1. Location of study area off Cabo San Lucas, Mexico. Figura 1. Ubicación geográfica del área de estudio frente a Cabo San Lucas, México.

Recognizable prey items were divided into major taxonomic categories. Prey were quantified and expressed as a percentage of volume (mL) (Hyslop, 1980): V (%) = (v/vT)x100; where v is volume displaced by a prey species and vT is volume displaced by all prey. A multivariate analysis of variance (MANOVA) of percent volume values was used to examine differences in prey consumed related to sex and size class.

The theoretical maximum capacity of the stomach (Stillwell & Kohler, 1982) was used to quantify the degree of stomach fullness. Stomach fullness was recorded according to an estimated fourth-point scale as percentages of total fullness: 0-25% full, 26-50% full, 51-75% full, and 76-100% full.

Estimates of mean daily and annual food consumption were made from the stomach contents of all striped marlin collected (applying the conversion 1 mL = 1 g) (Stillwell & Kohler, 1985). The values were extrapolated to fish hooked by the eight fishing fleets in Cabo San Lucas (Klett-Traulsen et al., 1996) to estimate the relative contribution of prey biomass (metric tons, ton) consumed by striped marlin.

Food evacuation time was estimated based on the type of prey (Olson & Boggs, 1986). For example, scombrids (mackerel) are evacuated in 5.29 h on average, whereas cephalopods take 2.24 h. Given the lack of information on the time-course for evacuation, the mean evacuation time of 5.29 h calculated for yellowfin tuna Thunnus albacares was used (Olson & Boggs, 1986). It was assumed that the evacuation time of yellowfin tuna is adequate for estimating daily rations of striped marlin because chub mackerel is one the most important elements in the diet of both the marlin and tuna predators. It was assumed that this rate of evacuation is unaffected by predator size, prey size, and sea temperature (Stillwell & Kohler, 1985).

RESULTS

Mean postorbital length was 176.81 ± 11.47 cm (± 1 SD) and mean weight was 56.14 ± 10.95 kg. Of 505 striped marlin that were sampled, 452 had food in their stomachs (89.6%), 27 had empty stomachs (5.3%), and 26 had regurgitated (5.1%). Taxonomic work identified 42 taxa (31 fishes, 6 cephalopods, and 5 crustaceans) belonging to 21 families and 35 genera (Table 1).

Table 1. Summary of food categories in stomachs (n = 452) of striped marlin from the southern of Gulf of California, Mexico expressed as absolute values and percentages of the volumetric values (V). Tabla 1. Resumen de las categorías alimentarias encontradas en contenidos estomacales (n = 452) de marlín rayado en la boca del golfo de California, México los resultados están expresados en valores absolutos y porcentuales en términos del volumen de las presas (V).

Stomach contents displaced a total volume (mL) of 231l, of which 87.6% were fish, 11.5% cephalopods, and 0.9% crustaceans. The main species were chub mackerel Scomber japonicus (29%), California pilchard Sardinops caeruleus (15.8%), jumbo squid Dosidicus gigas (10%), and the redeye round herring Etrumeus teres (8.5%). The postorbital length frequency distribution in the 505 striped marlin was 120 to 221 cm, with the 171-180 cm size class (36%) most prevalent (Fig. 2). The largest number of empty stomachs occurred in marlin ranging from 151-200 cm, with only one empty stomach in marlin ranging from 121-140 cm.

Figure 2. Frequency of postorbital length (cm) of striped marlin collected between 1987-1989 off Cabo San Lucas, Mexico. Figura 2. Distribución de clases de talla (longitud postorbital en cm) para marlín rayado capturado en el periodo 1987-1989 frente a Cabo San Lucas, México.

Prey consumption also varied with size (Table 1). MANOVA revealing significant differences in consumption patterns for the size classes (P < 0.0001), with Tukey's test (Sokal & Rohlf, 1981) indicating that striped marlin <180 cm PL consumed a more diverse group of fish (n = 30) compared to marlin >180 mm PL (n = 15; Table 1). In contrast, for cephalopod and crustacean prey, no significant differences (P > 0.05) were noted between size classes (11 vs 6 prey species, respectively) (Table 1).

Of the sample, there were 297 females (58.8%) and 208 males (41.2%), a sex ratio of 1.4:1. MANOVA revealed highly significant differences (P < 0.0001) in diet based on sex (Table 2) and Tukey's test showed that females consumed twice as much fish as males. In contrast, consumption of cephalopods and crustaceans were not significantly (P > 0.05) different between genders.

Mean maximum capacity of striped marlin stomachs was 2.5 L, which is ~4.4% of the weight of the average striped marlin. Of 452 stomachs with prey, 261 (57.7%) had a fullness status of 0-25%; 120 (26.5%) had 26-50%; 48 (10.6%) had 51-75%; and 23 (5.1%) had 76-100% (Table 3). Stomach fullness in all seasons there was a tendency for fuller stomachs in larger striped marlin (Table 4).

Table 3. Summary of food categories of female (n = 279) and male (n = 173) striped marlin from the southern Gulf of California, Mexico, expressed as absolute values and percentages of the volumetric values (V). Tabla 3. Composición de categorías de presa encontradas en hembras (n = 279) y machos (n = 173) de marlín rayado en la boca del golfo de California, México expresado como valores absolutos y porcentuales con base al volumen de las presas (V).

Table 4. Seasonal frequency by size interval (cm), sex ratio (F: female, M: male), mean volume of the stomach contents and degrees of fullness (1: 1-25%; 2: 26-50%; 3: 51-75; 4: 76-100%). Tabla 4. Variación estacional por intervalo de talla (cm), proporción de sexos (F: hembra, M: macho), volumen promedio del contenido estomacal y grado de llenado (1: 1-25%; 2: 26-50%; 3: 51-75% y 4: 76-100%).

Since chub mackerel was the main food for striped marlin near Los Cabos, calculation of the daily biomass consumption included mean gastric evacuation time of 5.3 h and a mean daily consumption of 0.51 kg per striped marlin. The latter value corresponds to the mean amount of food consumed by 452 striped marlin, which was equivalent to 1% of the mean weight (56.1 kg) of the striped marlin sampled.

Based on the assumption that predicted striped marlin need 5.29 h to evacuate food (21.16 h), it was marlin feed four times daily. When multiplying this by the mean biomass consumed (0.51 kg), daily consumption of an adult marlin was ~2.04 kg, ~3.6% of mean weight. By extrapolating the calculated daily consumption over the estimated capture of 12,166 striped marlin hooked by eight sport fleets from Cabo San Lucas over 27 months (Klett-Traulsen et al., 1996), it was estimated 24.8 ton of prey were consumed or an annual consumption rate of 11.02 ton.

To estimate the biomass of the main prey species consumed by striped marlin, the percent volume for each food type was calculated and converted to biomass: chub mackerel 29% (7.2 ton); California pilchard 15.8% (3.9 ton); jumbo squid 10% (2.5 ton); redeye round herring 8.5% (2.1 ton); Pacific hake Merluccius productus, 7.2% (1.8 ton); the carangid Decapterus muroadsi 6.3% (1.6 ton); and the scombrid Auxis spp. 3.6% (0.9 ton) (Fig. 3).

Figure 3. Plot of the biomass (ton) of the most important prey of striped marlin. SJA: Scomber japonicus, SCA: Sardinops caeruleus, DGI: Dosidicus gigas, ETE: Etrumeus teres, MPR: Merluccius productus, CAR: Carangidae, DMU: Decapterus muroadsi, SER: Serranidae, AUX: Auxis spp., BPO: Balistes polylepis, SCR: Selar crumenophthalmus, OLI: Opisthonema libertate and CLU: Clupeidae. Figura 3. Contribución en términos de biomasa (ton) de las presa principales consumidas por el marlín rayado: SJA: Scomber japonicus, SCA: Sardinops caeruleus, DGI: Dosidicus gigas, ETE: Etrumeus teres, MPR: Merluccius productus, CAR: Carangidae, DMU: Decapterus muroadsi, SER: Serranidae, AUX: Auxis spp., BPO: Balistes polylepis, SCR: Selar crumeno-phthalmus, OLI: Opisthonema libertate y CLU: Clupeidae.

DISCUSSION

All billfishes are considered epipelagic (Block et al., 1992a; Nakamura, 1995). Striped marlin are found in more temperate waters than others istiophorids, with strong preferences for waters 20-25°C (Ueyanagi, 1965; Domeier, 2006). Tracking of horizontal and vertical movements show that striped marlin spend most of the time in surface waters (10 m), but dive to depths of 170 m, suggesting that their vertical movements are strongly influenced by water temperature (Brill et al., 1993). In general, telemetry tracking of billfish revealed that species, such as striped marlin and blue marlin (Makaira nigricans), make short vertical migrations to moderate depths, while swordfish (Xiphias gladius) dive deeper and longer (Block et al., 1992a, 1992b; Sedberry & Loefer, 2001; Takahashi et al, 2003).

In waters surrounding Cabo San Lucas, BCS, Mexico, striped marlin mainly consume epipelagic prey in the neritic zone, and to a lesser extent, prey from deeper waters. Common prey was chub mackerel, California pilchard, and jumbo squid, which are important components of the commercial harvest in the eastern Pacific Ocean (Ehrhart et al, 1986; Gluyas-Millan & Quiñonez-Velazquez, 1996; Felix-Uraga et al, 1996), with the jumbo squid also preying on the other two former species. On the other hand, epipelagic (neritic and oceanic zones), demersal, and benthic species in the diet of striped marlin suggest it migrates vertically and horizontally to feed.

A high number of top predators eat the most abundant prey found in their environment (Olson & Galván-Magaña, 2002; Young et al., 2006; Arizmendi-Rodríguez et al., 2006). Migrating habits of striped marlin might also reflect a reproductive strategy that includes searching for water masses with adequate conditions for growth and survival of their larvae and prey for their juveniles and immature adults. Several authors consider these migrations as behavior to ensure favorable reproduction conditions (Radakov, 1973; Lagler et al, 1977).

The sizes recorded (111-221 cm postorbital length) in this study match those reported for other striped marlin sport fisheries, but not matching the longline Japanese commercial fishery records that have both smaller and larger sizes. For example, the length of striped marlin in the longline Japanese commercial fishery is 80-240 cm (Shingu et al, 1974; Miyabe & Bayliff, 1987) while the offshore areas of Mazatlan and Sonora yield marlin ranging from 110-204.5 cm (Wares & Sakagawa, 1974), and Buenavista and Los Cabos, B.C.S. range from 107.5-225.5 cm (Wares & Sakagawa, 1974; Ponce-Diaz et al, 1991). The range of striped marlin postorbital length size classes in our study is wide because of the selectivity of the fishing methods and the spectrum of sizes in the waters near Los Cabos. Thus, our data reflects the length of striped marlin throughout much of its range.

Striped marlin exhibited significant ontogenetic and sex differences in diet. Striped marlin with size <180 cm PL fed on a larger number of fish species and consume greater biomass, while striped marlin >180 cm PL, which consume fewer fish species and biomass. Additionally, female marlin had a larger percentage of filled stomachs and consuming twice the fish biomass of males.

Estimating daily consumption of this apex predator in their environment is difficult because several factors, such as size of fish and their food, water temperature, and digestion and evacuation rates play a major role. Studies of several species of teleostean fish and sharks to determine stomach evacuation rates and daily ratio have been done (Stillwell & Kohler, 1985; Olson & Boggs, 1986; Olson & Mullen, 1986; Olson & Galván-Magaña, 2002). However, studies for billfishes are lacking because direct measurements on these fish are not possible because of logistic constraints, including their pelagic habitat, large size, and wide-roving behavior, and the technology for maintaining these large marine fishes in optimal conditions in the laboratory or in a natural enclosure in the sea, has not been developed.

In our study, only approximate calculations can be made of daily consumption by employing gastric evacuation rates of species with similar characteristics of standard metabolic rates and high-performance physiology, such as tuna and dolphin fishes (Brill, 1996; Olson & Galván-Magaña, 2002). Considering the mean weight of the stomach content of 452 striped marlin and the mean gastric evacuation rate of yellowfin tuna (5.29 h), we estimated that striped marlin eat 2.04 kg prey each day, approximately 3.6% of their mean weight. This value seems reasonable and is comparable with estimates made for other predator species. For example, an estimate of 0.3% of body weight for the shark Ginglymostoma spp. (Clark, 1963), 5.6% of body weight of common dolphinfish Coryphaena hippurus (Olson & Galván-Magaña, 2002) and 10% of body weight for blue fin tuna Thunnus thynnus (Butler & Mason, 1977). For billfish, the only previously published estimate of daily consumption is for the swordfish Xiphias gladius, which consumed 0.93 kg of prey, representing 1.6% of mean body weight (Stillwell & Kohler, 1985).

Indirectly, this study on the feeding habits of striped marlin provides an assessment of the relative abundance of the main prey species in their diet. Chub mackerel represented 28.9% (7.2 ton); California pilchard, 15.8% (3.9 ton); and jumbo squid 10% (2.5 ton) of the overall diet. Extrapolating the estimated daily consumption (2.04 kg) to an estimated 12,166 striped marlin hooked by the sport fishing fleet of Cabo San Lucas from October 1987 through December 1989 (27 months) suggests 24.8 ton of prey consumed and an annual food consumption rate of 11.02 ton. It needs to be stressed that these estimates should be considered as minimums because 84.2% of the stomachs were less than 50% of estimated maximum capacity.

Striped marlin are apex predator in the pelagic food web in the southern Gulf of California and the results support the assumption that billfish and others large pelagic fish may be of keystone predators in the marine ecosystem (Hinman, 1998; Kitchell et al., 2006). Additionally, these results provide key data for implementing ecosystem analysis based on food web models (Kitchell et al., 2006).

ACKNOWLEDGEMENTS

We wish to thank the Instituto Politécnico Nacional (COFAA, EDI) and the Centro de Investigaciones Biológicas del Noroeste for their support. Thanks Consejo Nacional de Ciencia y Tecnología (CONACyT) and Sistema Nacional de Investigadores (SNI). Finally thanks to Ira Fogel for editing the English-language text and Ing. Armando Hernandez-Lopez for the edition of figures and tables.

 

REFERENCES

Abitia-Cárdenas, L.A., F. Galván-Magaña & J. Rodríguez-Romero. 1997. Food habits and energy values of prey of striped marlin Tetrapturus audax (Philippi, 1887) off the coast of Mexico. Fish. Bull., 95: 360-368.

Abitia-Cárdenas, L.A., F. Galván-Magaña & A. Muhlia-Melo. 1998. Trophic spectrum of striped marlin Tetrapturus audax (Philippi, 1887), off the coast of Cape San Lucas, Baja California Sur, Mexico. Rev. Biol. Mar. Oceanogr., 33: 277-290.

Abitia-Cárdenas, L.A., A. Muhlia-Melo, V.H. Cruz-Escalona & F. Galván-Magaña. 2002. Trophic dynamics and seasonal energetics of striped marlin Tetrapturus audax in the southern Gulf of California, Mexico. Fish. Res., 57: 287-295.

Allen, G.R. & D.R. Robertson. 1994. Fishes of the tropical eastern Pacific. University Hawaii Press, Hawaii, 332 pp.

Arizmendi-Rodríguez, D.I., L.A. Abitia-Cárdenas, F. Galván-Magaña & I. Trejo-Escamilla. 2006. Food habits of sailfish Istiophorus platypterus off Mazatlan, Sinaloa, Mexico. Bull. Mar. Sci., 79(3): 777-791.

Block, B.A., D. Booth & F.G. Carey. 1992a. Depth and temperature of the blue marlin, Makaira nigricans, observed by acoustic telemetry. Mar. Biol., 114: 175-183.

Block, B.A., D. Booth & F.G. Carey. 1992b. Direct measurement of swimming speeds and depth of blue marlin. J. Exp. Biol., 166: 267-284.

Brill, R.W. 1996. Selective advantages conferred by the high performance physiology of tunas, billfishes, and dolphin fish. Comp. Biochem. Phys. A., 113A(1): 315.

Brill, R.W., D.B. Holts, R.K.C. Chang, S. Sullivan, H. Dewar & F.G. Carey. 1993. Vertical and horizontal movements of striped marlin (Tetrapturus audax) near the Hawaiian Islands, determined by ultrasonic telemetry, with simultaneous measurement of oceanic currents. Mar. Biol., 117: 567-574.

Brusca, R.C. 1980. Common intertidal invertebrates of the Gulf of California., University Arizona Press, Tucson, 513 pp.

Butler, M.J.A. & J.M. Mason. 1977. Behavioral studies on impounded bluefin tuna. Int. Comm. Conserv. Atl. Tunas Coll. Vol. Sci. Pap., 7(2): 379-381.

Clark, E. 1963. The maintenance of sharks in captivity, with a report on their instrumental conditioning. In: P. Gilbert (ed.). Sharks and survival. Boston, DC Heath., pp. 115-149.

Clarke, M.R. 1986. A handbook for the identification of cephalopod beaks. Clarendon Press, Oxford, 273 pp.

De Silva, D.P. 1962. Red water blooms off northern Chile, April-May 1956, with reference to the ecology of the swordfish and the striped marlin. Pac. Sci., 16: 271-279.

Domeier, M.L. 2006. An analysis of Pacific striped marlin (Tetrapturus audax) horizontal movement patterns using pop-up satellite archival tags. Bull. Mar. Sci., 79(3): 811-825.

Ehrhart, N.M., A. Solis-Nava, S.J. Pierre, J. Ortiz-Cobos, P. Ulloa-Ramírez, G. González-Dávila & F. García-Badillo. 1986. Análisis de la biología y condiciones del stock del calamar gigante Dosidicus gigas en el Golfo de California, durante 1980. Cienc. Pesq., 5: 63-76.

Eldrige, M.B. & P.G. Wares. 1974. Some biological observations of billfishes taken in the eastern Pacific Ocean. In: R.S. Shomura & F. Williams (eds.). Species synopsis. Proceedings of the International Billfish Symposium. Kailua-Kona, Hawaii, 9-12 August 1972, NOAA. Tech. Rep., NMFS-SSRF-675, pp. 89-101.

Evans, D.H. & G. Wares. 1972. Food habits of the striped marlin and sailfish off México and southern California. Fish Wildlife Serv. Res. Rep., 76: 1-10.

Felix-Uraga, R., R.M. Alvarado-Castillo & R. Carmona-Piña. 1996. The sardine fishery along the western coast of Baja California, 1981 to 1994. CalCOFI Rep., 37: 188-192.

Fischer, W., F. Krupp, W. Schneider, C. Sommer, K.E. Carpenter & V.H. Niem. 1995. Guía FAO para la identificación de especies para los fines de pesca. Pacífico centro-oriental. Vol. II y III. Vertebrados Parte 1 y 2, FAO, pp. 647-1813.

Gluyas-Millan, M.G. & C. Quiñonez-Velazquez 1996. Evidence of differents stocks of mackerel Scomber japonicus. Cienc. Mar., 22: 377-395.

González-Armas, R., O. Sosa-Nishizaki, R. Funes-Rodríguez & V.A. Levy-Perez. 1999. Confirmation of the spawning area of the striped marlin, Tetrapturus audax, in the so called core area of the eastern tropical Pacific off Mexico. Fish. Oceanogr., 8: 238-242.

Hinman, K. 1998. Ocean roulette: conserving swordfish, sharks and other threatened pelagic fish in longline-infested waters. Nat. Coal. Mar. Conserv., Leesburg, Virginia, http://www.savethefish.org/PDF_files/ocean_roulette.pdf., 11 pp.

Hubbs, C.L. & R.L. Wisner. 1953. Food of marlin in 1951 off San Diego California. Calif. Fish Game, 39: 127-131.

Hyslop, E.J. 1980. Stomach contents analysis, a review of methods and their application. J. Fish Biol., 17: 411-429.

Kitchell, J.F., S.J.D. Martell, C.J. Walters, O.P. Jensen, I. Kaplan, J. Watters, T.E. Essington & C.H. Boggs. 2006. Billfishes in an ecosystem context. Bull. Mar. Sci., 79(3): 669-682.

Klett-Traulsen, A., G. Ponce-Díaz & S. Ortega-García. 1996. Pesquería deportiva-recreativa. In: M.M. Casas-Váldez & G. Ponce-Díaz (eds.). Estudio del potencial pesquero y acuícola de Baja California Sur. Vol II. SEMARNAP, Gobierno del Estado de BCS, FAO, UABCS, CIBNOR, CICIMAR, CRIP, CETMAR, pp. 389-418.

Lagler, K.F., J.E. Bardach, R.R. Miller & P.D. May. 1977. Ictiología. AGT. México, D.F., 489 pp.

Miller, G.J. & S.C. Jorgensen. 1973. Meristic characters of some marine fishes of the western Atlantic Ocean. Fish. Bull., 71: 301-312.

Miller, D.J. & N. Lea. 1972. Guide to the coastal marine fishes of California. Calif. Fish Game, Fish Bull., 157: 1-235.

Miyabe, N. & W.H. Bayliff. 1987. A review of the Japanese longline fishery for tunas and billfishes in the eastern Pacific Ocean, 1971-1980. Bull. I-ATCC/Bol. CIAT, 19: 1-163.

Nakamura, I. 1995. Isthiophoridae. Agujas, marlines, peces vela. In: W. Fischer, F. Krupp, W. Schneider, C. Sommer, K.E. Carpenter & V.H. Niem (eds.). Guía FAO para la identificación de peces para los fines de pesca. Pacífico centro-oriental. Vol. II. Vertebrados, Parte 1. FAO, Rome, pp.1186-1194.

Olson, R.J. & A.J. Mullen. 1986. Recent developments for making gastric evacuation and daily ration determinations. Environ. Biol. Fishes, 16: 183-191.

Olson, R.J. & C.H. Boggs. 1986. Apex predation by yellowfin tuna (Thunnus albacares); independent estimates from gastric evaluation and stomach contents, bioenergetics, and cesium concentrations. Can. J. Fish. Aquat. Sci., 43: 1760-1775.

Olson, R.J. & F. Galván-Magaña. 2002. Food habits and consumption rates of common dolphinfish (Coryphaena hippurus) in the eastern Pacific Ocean. Fish. Bull., 100: 279-298.

Ponce-Díaz, G., S. Ortega-García & P. González-Ramírez. 1991. Análisis de tallas y relación peso-longitud del marlín rayado Tetrapturus audax (Philippi, 1887). Cienc. Mar., 17: 69-82.

Radakov, D.V. 1973. Schooling in the ecology of fish. John Wiley & Sons, New York, 173 pp.

Sedberry, G.R & J.K. Loefer. 2001. Satellite telemetry tracking swordfish Xiphias gladius, off the eastern United States. Mar. Biol., 139: 355-360.

Shingu, C., P. Tomlinson & C. Peterson. 1974. A review of the Japanese longline fishery for tunas and billfishes in the eastern Pacific Ocean, 1967-1970. Bull. IATCC Bol., CIAT, 16: 68-230.

Sokal, R.R. & J.F. Rohlf. 1981. Biometry. The principles and practice of statistics in biological research. W. H. Freeman & Company, New York, 859 pp.

Sosa-Nishizaki, O. 1998. Revisión histórica del manejo de los picudos en el Pacífico Mexicano. Cienc. Mar., 24: 95-111.

Squire, J.L. & Z. Suzuki. 1990. Migration trends of striped marlin (Tetrapterus audax) in the Pacific Ocean. In: R.H. Stroud (ed.). Planning the future of billfishes: research and management in the 90's and beyond. Savannah, G.A. Nat. Coal. Mar. Conserv., pp. 67-80.

Stillwell, C.E. & N.E. Kohler. 1982. Food, feeding habits, and estimates of daily ration of the shortfin mako (Isurus oxyrinchus) in the northwest Atlantic. Can. J. Fish. Aquat. Sci., 39: 407-414.

Stillwell, C.E. & N.E. Kohler. 1985. Food and feeding ecology of the swordfish Xiphias gladius in the western North Atlantic Ocean with estimates of daily ration. Mar. Ecol. Prog. Ser., 22: 239-247.

Takahashi, M., H. Okamura, K. Yokawa & M. Okazaki. 2003. Swimming behaviour and migration of a swordfish recorded by an archival tag. Mar. Freshw. Res., 54: 527-534.

Wares, P. & G. Sakagawa. 1974. Some morphometrics of billfishes from the eastern Pacific Ocean. In: R.S. Shomura & F. Williams (eds.). Proceedings International Billfish Symposium. Kailua-Kona, Hawaii, 9-12 August 1972. NOAA. Tech. Rep., NMFS-SSRF-675, pp. 107-120.

Wolff, C.A. 1982. A beak key for eight eastern tropical Pacific cephalopods species, with relationship between their beak dimensions and size. Fish. Bull., 80: 357-370.

Young, J., M. Lansdell, S. Riddoch & A. Revill. 2006. Feeding ecology of broadbill swordfish Xiphias gladius off eastern Australia in relation to physical and environmental variables. Bull. Mar. Sci., 79(3): 793-899.

 

Received: 20 October 2010; Accepted: 28 September 2011

Corresponding author: Leonardo Abitia-Cárdenas (labitia@ipn.mx)