|Scientific Name:||Kajikia audax|
|Species Authority:||(Philippi, 1887)|
Histiophorus audax Philippi, 1887
Kajikia formosana Hirasaka & Nakamura, 1947
Tetrapturus audax (Philippi, 1887)
|Taxonomic Notes:||Previously, this species was included in the genus Tetrapturus (Collette et al. 2006).|
|Red List Category & Criteria:||Near Threatened ver 3.1|
|Assessor(s):||Collette, B., Acero, A., Boustany, A., Canales Ramirez, C., Cardenas, G., Carpenter, K.E., Di Natale, A., Die, D., Fox, W., Graves, J., Hinton, M., Juan Jorda, M., Minte Vera, C., Miyabe, N., Montano Cruz, R., Nelson, R., Restrepo, V., Schaefer, K., Schratwieser, J., Serra, R., Sun, C., Uozumi, Y. & Yanez, E.|
|Reviewer(s):||Russell, B., Elfes, C. & Polidoro, B.|
This species is widespread in the Indian and Pacific oceans. It is an important commercial and recreational resource throughout its range, with the largest catches taken as bycatch by the pelagic longline fisheries targeting tunas. Globally, it is estimated that this species has declined 20–25% over three generation lengths (16 years). This species is not considered to be well managed and stock assessments are needed especially in the Indian Ocean and the Northwest Pacific. It is listed as Near Threatened as it nearly meets the thresholds for criterion A2.
|Range Description:||This species is widely distributed in tropical and temperate waters of the Indo-Pacific and strays are occasionally found in the southeastern Atlantic. It is strongly oceanic, and rarely enters coastal waters. It is the most widely distributed of all Pacific billfishes, especially in the eastern and northern Central Pacific, where it is much more abundant than in the Western Pacific.
Historic Japanese longline records indicate that adult Striped Marlin have a somewhat horseshoe shaped distribution in the Pacific Ocean (Nakamura 1985) which is unique among Pacific billfish and tunas. The base of this distribution is centred on the south central American coast, and has extensions which run either side of the equator right across to the Western Pacific Ocean (Nakamura 1985). The central equatorial region in the western and central Pacific is characterized by very low and intermittent hook rate for Striped Marlin, and thus is not considered part of their normal distribution (Ueyanagi and Wares 1975).
According to early longlining data, the areas of highest abundance were in the central north and the eastern Pacific, while the waters of the south and western Pacific were areas of lesser abundance (Ueyanagi and Wares 1975). In the south and southwest Pacific, adults are most abundant during the spring and summer and least abundant in the winter. This region includes eastern Australian, where striped marlin are present from the Coral Sea to Tasmania (depending on currents and seasons).
In the Eastern Pacific the distribution stretches from California to the southwestern and central eastern Gulf of California to Peru, including all of the oceanic islands.
Native:American Samoa (American Samoa); Australia; Bangladesh; British Indian Ocean Territory; Chile (Easter Is.); China; Christmas Island; Cocos (Keeling) Islands; Colombia; Comoros; Cook Islands; Costa Rica; Djibouti; Ecuador (Galápagos); El Salvador; Eritrea; Fiji; French Polynesia; Guam; Guatemala; Honduras; India (Andaman Is., Nicobar Is.); Indonesia; Iran, Islamic Republic of; Japan; Kenya; Kiribati; Korea, Democratic People's Republic of; Korea, Republic of; Madagascar; Malaysia; Maldives; Marshall Islands; Mauritius; Mayotte; Mexico; Micronesia, Federated States of ; Mozambique; Myanmar; Nauru; New Caledonia; New Zealand; Nicaragua; Niue; Norfolk Island; Northern Mariana Islands; Oman; Pakistan; Palau; Panama; Papua New Guinea; Peru; Philippines; Pitcairn; Réunion; Russian Federation; Samoa; Seychelles; Singapore; Solomon Islands; Somalia; South Africa; Sri Lanka; Sudan; Taiwan, Province of China; Tanzania, United Republic of; Thailand; Tokelau; Tonga; Tuvalu; United States (Hawaiian Is.); United States Minor Outlying Islands (Howland-Baker Is., Johnston I., US Line Is., Wake Is.); Vanuatu; Viet Nam; Wallis and Futuna; Yemen
|FAO Marine Fishing Areas:||
Atlantic – southeast; Indian Ocean – eastern; Indian Ocean – western; Pacific – eastern central; Pacific – northeast; Pacific – northwest; Pacific – southeast; Pacific – southwest; Pacific – western central
|Range Map:||Click here to open the map viewer and explore range.|
McDowell and Graves (2008) indicate that there are four stocks of this species: one centred in Hawaii, one in Australia and New Zealand, and two in the Eastern Tropical Pacific. At present, assessments have been conducted for the Southwest Pacific (Langley et al. 2006), and for the northeastern Pacific (Hinton and Maunder 2011). Preliminary assessments have been conducted for the entire Pacific (Brodziak and Piner 2010), but a new stock assessment for the northwest Pacific is needed. Catch per unit effort (CPUE) data are available for the Indian Ocean (IOTC 2009), but a full stock assessment is needed.
The assessment model considered a single population of Striped Marlin within the region (the area is defined as the region from the equator to latitude 40ºS and from 140ºE to 130ºW). The estimated decline in spawning biomass over a three generation length period (from 1991–2006) was 8% (Figure 23, Langley et al. 2006). The results of the model were considered preliminary, as there remains a great deal of uncertainty regarding some of the key parameters included in the assessment model, in particular natural mortality and growth. Generally, the assessment indicates that current levels of fishing mortality may approximate or exceed FMSY and current biomass levels may approximate or be below BMSY (Langley et al. 2006). The fishery is not considered to be well managed.
There have been a number of studies of the stock structure of Striped Marlin in the Pacific Ocean. The most recent found that there was a single stock of Striped Marlin in the northeast Pacific Ocean and the assessment was based on this assumption. Spawning stock biomass was estimated using a Stock Synthesis model. Over a three generation length period (1992–2008), the population decline was calculated to be 0% as the spawning biomass has been increasing since 2003 (Figure 22.214.171.124, Hinton and Maunder 2011). The results indicate that the Striped Marlin stock in the Northeast Pacific is not overfished, and overfishing is not occurring.
There is a need for a new stock assessment for the northwest Pacific. Previous assessments have been conducted combining data from both eastern and western North Pacific (ISC 2007, Brodziak and Piner 2010). Using the available data from Brodziak and Piner, a decline of 55–60% was estimated for the North Pacific stock as a whole. It is likely that declines are in the order of 40–50% for the Northwest Pacific (Hinton pers. comm. 2011). A value of 55% was used for this stock, however, more information is needed to characterize declines for this population. This stock is not considered to be well managed.
Nominal yearly CPUE of Japanese longliners in northwest Australia has declined 40.1% over a three generation length period (1991–2007; Figure 40, IOTC 2009). The CPUE decline for Japanese longliners in the Seychelles was 95% over the same period (Figure 40, IOTC 2009). An average of these two declines was used to characterize the population in the Indian Ocean, however these data are limited and catch data from other industrial fisheries such as longliners of Indonesia and Philippines are not available. The stock is not considered to be well managed and more information is needed to understand population declines for Striped Marlin in the Indian Ocean.
|Habitat and Ecology:||
This widely distributed pelagic and oceanodromous species is usually found above the thermocline. It has been found to depths of 289 m. It generally inhabits cooler water than either Black Marlin or Blue Marlin (Nakamura 1985). Abundance increases with distance from the continental shelf; usually seen close to shore only where deep drop-offs occur (Kailola et al. 1993). It is mostly solitary, but forms small schools by size during the spawning season. They are usually dispersed at considerably wide distances.
It feeds on a wide variety of fishes, crustaceans, and squids. Larvae are most abundant in the respective local early summers. The seasonal occurrence of mature females coincides with that of the larvae. The lower temperature limit in the distribution of larvae is approximately 24°C, both in the Indian and Pacific Oceans. Spawning sites are between 10°S and 30°S in the southwest Pacific and 10°S and 20°S in the northeastern Indian Ocean (Kailola et al. 1993).
Transmitted temperature and depth data indicate Striped Marlin spend 80% of their time in the mixed layer including 72% of their time in the top 5 m. Temperature data indicated 75% of the Striped Marlin’s time was spent in water temperatures between 20°C and 24°C (Sippel et al. 2007).
The results of an assessment of Striped Marlin in the northeast Pacific (Hinton and Maunder 2011) estimated that the unfished generation time (mean age weighted by fecundity at age) was about 5.3 years (Hinton pers. comm. 2011). This generation length has been applied to all stocks of Striped Marlin.
Maximum Size is 420 cm total length (TL). The all-tackle game fish record is of a 224.1 kg fish caught off Tutukaka, New Zealand in 1986 (IGFA 2011).
|Use and Trade:||This is an important commercial and recreational species.|
An important commercial and recreational resource throughout its range, with the largest catches taken as bycatch by the pelagic longline fisheries targeting tunas. Commercial catch is taken mostly by surface long lining with less than 1% of the total catch taken by harpooning. The quality of the flesh is among the best of the billfishes for sashimi and sushi. It marketed mostly frozen, sometimes fresh. The observed distribution of several large pelagic predators, including the striped marlin, has significantly contracted from the 1960s to 2000 (Worm and Tittensor 2011).
In the western central Pacific Ocean (WCPO), catches of Striped Marlin were dominated by the Japanese longline fleet until the early 1990s. Taiwanese and Korean fleets have reported relatively small catches of Striped Marlin since the mid 1960s and mid 1970s, respectively. However, Taiwanese catches have increased in recent years, mainly due to the high effort of this fleet in the eastern temperate WCPO, targeting mainly Albacore Tuna. Longline fleets of Pacific Island Countries and Territories, and by Australia and New Zealand, have reported increasing catches since the early 1990s mainly due to the development of these domestic fleets. Catches by Australian longline fleets have rapidly increased in recent years due, at least in part, to specific targeting of striped marlin by some vessels during some periods. Since 1987, longline fleets operating in the New Zealand Exclusive Economic Zone (EEZ) have been prohibited from landing Striped Marlin in an attempt support recreational fisheries in the north of the country (Kopf 2005). Extensive recreational fisheries exist throughout the southwest Pacific Ocean (Whitelaw 2001, Bromhead et al. 2004, Kopf 2005) although total catches by recreational fisheries are very small relative to commercial catches. In addition, a high proportion of Striped Marlin are (tagged and) released by recreational fisheries in the WCPO (up to 60%, Holdsworth et al. 2003, in Kopf et al. 2005). However, studies into the survival of recreationally captured marlin have estimated that between 0–50% of marlin suffer post-release mortality due to hook damage, stress or increased susceptibility to predation (Pepperell and Davis 1999), although studies are rare, sample sizes are typically small and the durations of monitoring of post-released fish are relatively short (e.g., maximum of 93 days for Striped Marlin, Domeier et al. 2003).
Fishing in the tropical eastern Pacific region is by both industrial and artisanal fisheries. Striped Marlin are caught mostly by the longline fisheries of Far East and Western Hemisphere national. Lesser numbers are caught by recreational, gillnet and other fisheries. This species may be threatened by the expansion of long line fisheries and also increased artisanal fisheries in the tropical eastern Pacific region.
This is a highly migratory species, listed in Annex I of the 1982 Convention on the Law of the Sea (FAO Fisheries Department 1994).
In the Western Central Pacific, the Western and Central Pacific Fisheries Commission (WCPFC) is tasked to undertake precautionary measures that will not permit increases in fishing mortality until the estimates of stock status are more certain. The Commission is tasked with reporting the number of vessels fishing for striped marlin and report on catch levels.
There are no conservation measures for this species in the Eastern Pacific. It is recommended that there should not be an increase in fishing for this species in the northern population in the Eastern Pacific.
Similarly, the International Scientific Committee for Tuna and Tuna-like species for the North Pacific Ocean (ISC) recommended that fishing mortality for Striped Marlin in the North Pacific not be permitted to exceed current levels.
There are no management measures for Striped Marlin in the Indian Ocean.
|Citation:||Collette, B., Acero, A., Boustany, A., Canales Ramirez, C., Cardenas, G., Carpenter, K.E., Di Natale, A., Die, D., Fox, W., Graves, J., Hinton, M., Juan Jorda, M., Minte Vera, C., Miyabe, N., Montano Cruz, R., Nelson, R., Restrepo, V., Schaefer, K., Schratwieser, J., Serra, R., Sun, C., Uozumi, Y. & Yanez, E. 2011. Kajikia audax. The IUCN Red List of Threatened Species. Version 2015.2. <www.iucnredlist.org>. Downloaded on 01 July 2015.|
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