|Scientific Name:||Xiphias gladius|
|Species Authority:||Linnaeus, 1758|
|Infra-specific Taxa Assessed:|
Phaethonichthys tuberculatus Nichols, 1923
Xiphias estara Phillipps, 1932
Xiphias imperator Bloch & Schneider, 1801
Xiphias thermaicus Serbetis, 1951
|Red List Category & Criteria:||Least Concern ver 3.1|
|Assessor/s:||Collette, B., Acero, A., Amorim, A.F., Bizsel, K., Boustany, A., Canales Ramirez, C., Cardenas, G., Carpenter, K.E., de Oliveira Leite Jr., N., Di Natale, A., Die, D., Fox, W., Fredou, F.L., Graves, J., Guzman-Mora, A., Viera Hazin, F.H., Hinton, M., Juan Jorda, M., Minte Vera, C., Miyabe, N., Montano Cruz, R., Masuti, E., Nelson, R., Oxenford, H., Restrepo, V., Salas, E., Schaefer, K., Schratwieser, J., Serra, R., Sun, C., Teixeira Lessa, R.P., Pires Ferreira Travassos, P.E., Uozumi, Y. & Yanez, E.|
|Reviewer/s:||Russell, B., Elfes, C. & Polidoro, B.|
Globally, this species has shown a 28% decline over three generation lengths (20 years). The only stock that is not considered to be well-managed is the Mediterranean, which comprises less than 10% of the species' global range. It is therefore listed as Least Concern, as it is below the threshold for a threatened category under Criterion A1.
|Range Description:||This species is pandemic, and is found in the Atlantic, Indian, and Pacific oceans in tropical, temperate and sometimes cold waters, including the Mediterranean Sea, the Sea of Marmara, the Black Sea, and the Sea of Azov.
Mitochondrial DNA restriction analysis reveal that genetic differentiation occurs between populations inhabiting the Mediterranean Sea and the tropical Atlantic Ocean, indicating little genetic exchange occurring between the two (Kotoulas et al. 1995).
In the Eastern Pacific, this species ranges from southern California and the mouth of the Gulf of California to Chile, including all of the offshore islands.
Native:Albania; Algeria; American Samoa (American Samoa); Angola (Angola); Anguilla; Antigua and Barbuda; Argentina; Aruba; Australia; Bahamas; Bangladesh; Barbados; Belize; Benin; Bermuda; Brazil; Bulgaria; Canada; Cape Verde; Cayman Islands; Chile (Easter Is.); China; Christmas Island; Cocos (Keeling) Islands; Colombia; Comoros; Congo; Congo, The Democratic Republic of the; Cook Islands; Costa Rica; Côte d'Ivoire; Croatia; Cuba; Cyprus; Denmark; Djibouti; Dominica; Dominican Republic; Ecuador (Galápagos); Egypt; El Salvador; Equatorial Guinea; Eritrea; Fiji; France; French Guiana; French Polynesia; Gabon; Gambia; Georgia; Germany; Ghana; Gibraltar; Greece; Greenland; Grenada; Guam; Guatemala; Guinea; Guinea-Bissau; Guyana; Haiti; Honduras; Iceland; India (Andaman Is., Nicobar Is.); Indonesia; Iran, Islamic Republic of; Ireland; Israel; Italy; Jamaica; Japan; Kenya; Kiribati; Korea, Republic of; Lebanon; Liberia; Libya; Madagascar; Malaysia; Maldives; Malta; Martinique; Mauritania; Mauritius; Mayotte; Mexico; Micronesia, Federated States of ; Monaco; Montenegro; Morocco; Mozambique; Myanmar; Namibia; Nauru; Netherlands; New Caledonia; New Zealand; Nicaragua; Nigeria; Niue; Norfolk Island; Northern Mariana Islands; Norway; Oman; Pakistan; Palau; Panama; Papua New Guinea; Peru; Philippines; Pitcairn; Portugal (Azores, Madeira); Puerto Rico; Réunion; Romania; Russian Federation; Saint Helena, Ascension and Tristan da Cunha; Saint Kitts and Nevis; Saint Lucia; Saint Vincent and the Grenadines; Samoa; Sao Tomé and Principe; Saudi Arabia; Senegal; Seychelles; Sierra Leone; Slovenia; Solomon Islands; Somalia; South Africa; South Georgia and the South Sandwich Islands; Spain (Canary Is.); Sri Lanka; Sudan; Suriname; Sweden; Syrian Arab Republic; Taiwan, Province of China; Tanzania, United Republic of; Thailand; Togo; Tokelau; Tonga; Trinidad and Tobago; Tunisia; Turkey; Turks and Caicos Islands; Tuvalu; Ukraine; United Arab Emirates; United Kingdom; United States (Alaska, Georgia, Hawaiian Is.); United States Minor Outlying Islands (Howland-Baker Is., Johnston I., US Line Is., Wake Is.); Uruguay; Vanuatu; Venezuela, Bolivarian Republic of; Viet Nam; Virgin Islands, British; Virgin Islands, U.S.; Wallis and Futuna; Western Sahara; Yemen
|FAO Marine Fishing Areas:||
Atlantic – western central; Atlantic – northeast; Atlantic – eastern central; Atlantic – southwest; Atlantic – southeast; Atlantic – northwest; Indian Ocean – western; Indian Ocean – eastern; Mediterranean and Black Sea; Pacific – southeast; Pacific – northeast; Pacific – northwest; Pacific – eastern central; Pacific – western central; Pacific – southwest
|Range Map:||Click here to open the map viewer and explore range.|
The Atlantic population is comprised of three stocks that are genetically distinct: South Atlantic, North Atlantic and Mediterranean. The best scientific evidence indicates that there are four stocks of Swordfish in the Pacific Ocean (Hinton and Alvarado Bremer 2007), with centres in the northwest, northeast, southwest, and southeast. The Indian Ocean population is currently assessed as a single management unit.
The North Atlantic stock of Swordfish is not overfished and overfishing is not occurring (ICCAT 2009). The stock is rebuilding with current biomass levels increasing by 4.4% over a three generation length period based on the ASPIC base case (Figure 20, ICCAT 2009). The reduction was calculated using the first and last data points of the time series considered. The stock is considered to be under adequate management.
The South Atlantic stock was overfished and overfishing had been occurring, but at present, fishing mortality is below FMSY, stock biomass is slightly above BMSY and under current management quotas (13,700 t TAC), the stock is projected to remain above the BMSY and slightly rebuild further (ICCAT 2009). The reduction in biomass for the South Atlantic stock over three generations has been approximately 30.3% based on the ASPIC base case (Figure 30, ICCAT 2009). The reduction was calculated using the first and last data points of the time series considered. The stock is considered to be under adequate management.
The Mediterranean stock is currently considered to be overfished and stock is experiencing slight overfishing. The International Commission for the Conservation of Atlantic Tunas Standing Committee on Research and Statistics (ICCAT-SCRS) report that the Mediterranean Sea swordfish compose a unique stock separated from the Atlantic, although more research is needed to clearly define the stock boundaries. Mitochondrial DNA restriction analysis reveal that genetic differentiation occurs between populations inhabiting the Mediterranean Sea and the tropical Atlantic ocean, indicating little genetic exchange occurring between the two (Kotoulas et al. 1995). The spawning stock biomass (SSB) in 2008 was 46% below the value that would maximize yield-per-recruit. In addition, the majority of the catch includes juveniles. However, landings statistics and population parameters indicate a certain stability over the past 20 years. The estimated decline in total biomass over a three generation period (20 years) ranged from 27–50% depending on whether a regression line or first and last points of the data series were used (Figure 21, ICCAT 2010). The Mediterranean population of Swordfish was therefore regionally assessed as Near Threatened in an overview of the conservation status of Mediterranean fishes (Abdul Malak et al. 2011). This stock is not considered to be well-managed.
In the North Pacific, a two-stock scenario analysing the western and central Pacific (subarea 1) and the eastern Pacific (subarea 2) was considered the most plausible based on analyses of Japanese longline catch per unit data (CPUE) data. Using the two-stock Bayesian production model (Brodziak and Ishimura 2009), a decline of 43.9% was estimated for subarea 1, and an increase of 111.2% in subarea 2 over a three generation length period (20 years). The decline was calculated using a linear regression over the time period considered. The results indicate that the North Pacific population is stable (Brodziak and Ishimura 2010).
In the Western Central Pacific, a MULTIFAN-CL stock assessment of south-west Pacific Swordfish showed a decline in total biomass ranging from 25.7% (optimistic scenario) to 36.9% (pessimistic scenario) over three generation lengths (20 years) (Figure 29, Kolody et al. 2008). The reduction was calculated using the first and last data points of the time series considered. The stock is considered to be under adequate management.
In the Southeastern Pacific, spawning biomass is estimated to have increased by 3.3% over three generation lengths (Figure 4.4, Hinton and Maunder 2006). The percent change was calculated using a linear regression over the time period considered. The stock is considered to be under adequate management.
For the Indian Ocean, an ASPIC model showed a decline in total biomass of 57.8% over the last three generation lengths (20 years) (Figure 59, IOTC 2010). The reduction was calculated using the first and last data points of the time series considered. The model results indicate that biomass is close to the BMSY level, and that overfishing is not presently occurring. The stock is considered to be under adequate management.
Globally, this species has shown a 28% decline over three generation lengths (20 years). The only stock that is not considered to be well-managed is the Mediterranean, which comprises less than 10% of the species' global range.
|Habitat and Ecology:||
This is an oceanic species, but sometimes found in coastal waters; generally above the thermocline, preferring temperatures of 18–22°C. It is primarily a warm-water species that migrates toward temperate or cold waters for feeding in the summer and back to warm waters in summer for spawning and overwintering. Adults are opportunistic feeders, known to forage for their food from the surface to the bottom over a wide depth range (Nakamura 1985). Swordfish typically forage in deep water during the day and stay in the mixed layer at night (Abascal et al. 2010). Based on records of forage organisms taken by swordfish, its depth distribution in the northwestern Pacific ranges normally from the surface to a depth of about 550 m but there are depth records down 2,878 m.
This species uses its sword to kill prey. It feeds mainly on fishes but also on crustaceans and squids. Large individuals may accumulate high concentrations of mercury in the flesh (Collette 1995).
The distribution of larval swordfish in the Pacific Ocean indicates that spawning occurs mainly in waters with a temperature of 24°C or more. Spawning appears to occur in all seasons in equatorial waters, but is restricted to spring and summer at higher latitudes (Nishikawa and Ueyanagi 1974). In the Atlantic Ocean, spawning occurs in the upper water layer at depths between 0–75 m, at temperatures around 23°C, and salinity of 33.8–37.4 ppt. Pairing of solitary males and females is thought to occur when spawning (Palko et al. 1981). Spawning in southern Brazil occurs from November to February in between 20–28°S and 40–47°W (Amorim and Arfelli 1980). Estimates of egg numbers vary considerably, from one million to 16 million in 168,000 g female (Palko et al. 1981) and 29 million in a 272,000 g female (Wilson 1984).
Determination of age is difficult since the otoliths are very small and scales are missing in adults. Year rings have been successfully counted on cross sections of the fin rays (Arocha et al. 2003, DeMartini et al. 2006). Longevity is estimated to be 15 years (based on Arocha et al. 2003, DeMartini et al. 2006), and age of first maturity is estimated to be five years (based on Arocha and Lee 1996, Hinton and Maunder, unpublished data). These life history parameters do not differ greatly between stocks, therefore, the generation length for this species was estimated to be 6.5 years globally. The generation length is calculated as: age of first reproduction + z * (longevity - age of first maturity), where z is 0.15 (Collette et al. 2011).
Maximum size is 445 cm. The all-tackle game fish record is of a 536.15 kg fish caught odd Iquique, Chile in 1953 (IGFA 2011).
This species is a highly important food and game species. Swordfish are caught by longline, harpoon, drift gill net, set net and other fishing gear in commercial fisheries. For the most part, swordfish captures are incidental in tuna longline fisheries. Major sport fishery areas, trolling, and drifted baited lines are located off the coast of California to Ecuador, Peru and northern Chile (Nakamura 1985). In the Mediterranean Sea, it is mostly caught by drift nets, long lines, but also by harpoons, tuna traps and sport and recreational fisheries. It is a good food fish, marketed fresh or frozen.
The largest proportion of Atlantic catches are made using surface drifting longlines, mostly by Spain, United States, Canada and Portugal. However, many additional gears are used (STECF 2009). Other directed swordfish fisheries include fleets from Brazil, Morocco, Namibia, EC-Portugal, South Africa, Uruguay, and Venezuela. The primary by-catch or opportunistic fisheries that take swordfish are tuna fleets from Chinese Taipei, Japan, Korea and EC-France. The tuna longline fishery started in 1956 and has operated throughout the Atlantic since then, with substantial catches of swordfish that are produced as a bycatch of tuna fisheries (ICCAT 2009). In the Atlantic, the Mediterranean stock is considered to be overfished and that overfishing is occurring. The stocks of the North and South Atlantic are considered to be well-managed (ICCAT 2009).
In the Indo-Pacific the main fisheries are Japan and Taiwan. Taiwan has had stable standardized CPUE trends, and Japan has shown variable CPUE trends depending on the fishing area (IOTC 2009). The Indian Ocean, Western Central Pacific and Southeastern Pacific are similarly considered to be under adequate management at present (fishing mortality below Fmsy and biomass above Bmsy; Kolody et al. 2008, IOTC 2009, Hinton and Maunder 2006).
This is a highly migratory species, listed in Annex I of the 1982 Convention on the Law of the Sea (FAO Fisheries Department 1994).
There have been some changes in U.S. regulations which may have impacted catch rates, but the effects of these remain unknown. It is important to note that since 2003 the catches have been below the total allowable catches (TACs), greatly increasing chances of a fast recovery (STECF 2009). The total allowable catch in the North Atlantic during the 2007–2008 period was 14,000 t per year. The reported catch during that period averaged 11,536 t and did not exceed the TAC in any year. The total allowable catch in the South Atlantic for the years 2007 through 2008 was 17,000 t. The reported catch during that period averaged 13,365, and did not exceed the TAC in any year. There are two minimum size options that are applied to the entire Atlantic: 125 cm LJFL with a 15% tolerance, or 119 cm LJFL with zero tolerance and evaluation of the discards.
Since 1994 there have been quotas and minimum size limits to restrict the harvest of north Atlantic Swordfish. There are also longline area closures in place in the U.S. Atlantic. Reduced landings have been attributed to the International Commission for the Conservation of Atlantic Tunas (ICCAT) regulatory recommendations and shifts in fleet distributions, including the movement of some vessels some years to the South Atlantic or out of the Atlantic. In addition, some fleets, including the United States, EC-Spain, EC-Portugal and Canada, have changed operating procedures to opportunistically target tuna and/or sharks, taking advantage of market conditions and higher relative catch rates of these species previously considered as by-catch in some fleets. Recently, socio-economic factors may have also contributed to the decline in catch. Consistent with the goal of the Commission’s swordfish rebuilding plan (Rec. 96-02), in order to maintain the northern Atlantic Swordfish stock at a level that could produce maximum sustainable yield (MSY) with greater than 50% probability, the Committee recommends reducing catch limits allowed by Rec. 06-02 (15,345 t) to no more than 13,700 t. This reflects the current best estimate of maximum yield that could be harvested from the population under existing environmental and fishery conditions. Should the Commission wish to have greater assurance that future biomass would be at or above BMSY while maintaining F at or below FMSY, the Commission should select a lower annual TAC, depending on the degree of precaution the Commission chooses to apply in management. The Committee noted that allowable catch levels agreed in (Recs. 06-02 and 08-02) exceeded scientific recommendations. The successful rebuilding of this stock could have been compromised if recent catches had been higher than realized. Because of the poor size-selectivity of longliners, regulating minimum landing size may inadvertently have resulted in under-reporting of juvenile catches. Alternative methods for reducing juvenile catches, such as time and/or area closures or technological changes in gear deployment, may be more effective and their utility should be further investigated (STECF 2009). Future TACs above MSY are projected to result in 50% or lower probabilities of the stock biomass remaining above BMSY over the next decade (SWO-ATL-Figure 13) as the resulting probability of F exceeding FMSY for these scenarios would trend above 50% over time. A TAC of 13,000 t would provide approximately a 75% probability of maintaining the stock at a level consistent with the Convention Objective over the next decade (ICCAT 2009).
Until more research has been conducted to reduce the high uncertainty in stock status evaluations for the southern Atlantic swordfish stock, the Committee emphasizes that annual catch should not exceed the provisionally estimated MSY (15,000). Considering the unquantified uncertainties and the conflicting indications for the stock, the Committee recommends a more precautionary Fishery Management approach, to limit catches to the recent average level (~15,000 t), which are expected to maintain the catch rates at about their current level (STECF 2009). In general, catches of 14,000 t or less will result in increases in the biomass of the stock, catches on the order of 15,000 will maintain the biomass of the stock at approximately stable levels during the period projected. Catches in the order of 16,000 t or more will result in biomass decrease. The current TAC is 17,000 t (ICCAT 2009).
In the Mediterranean Sea, there are minimum size regulations, such as 90cm lower jaw-fork length in Spain, 140 upper jaw fork-length in Italy, 130 UJFL in Turkey. However, these minimum size regulations were cancelled because it was considered ineffective as a management tool. In Greece, the fishing season is closed from October to January. In 2009, ICCAT adopted a closed season for the Mediterranean Sea from 1 October to 31 November. The EU has banned all drift nets since January 2002 and ICCAT banned them since 2005 (some illegal drift nets still occur).
In Chile there is a size limit for this species, and total effort for this species has declined as they moved from driftnets to longlines. However, recent catches in this region are mostly targeted by the Spanish fleet. Given the potential for rapid change in the nature of the gill-net and longline fisheries that are increasingly targeting swordfish in the Eastern Pacific region, the trends in standardized catch per unit effort should be closely monitored for indications of changing status of these stocks (Hinton 2003, Hinton and Maunder 2006). The Western Central Pacific Fisheries Commission has recommended to limit the number of boats as well as catch and effort for the southwestern stock (WCPFC 2008).
The Scientific Committee recommends that management measures focused on controlling and/or reducing effort in the fishery targeting Swordfish in the southwest Indian Ocean be implemented (IOTC 2006).
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|Citation:||Collette, B., Acero, A., Amorim, A.F., Bizsel, K., Boustany, A., Canales Ramirez, C., Cardenas, G., Carpenter, K.E., de Oliveira Leite Jr., N., Di Natale, A., Die, D., Fox, W., Fredou, F.L., Graves, J., Guzman-Mora, A., Viera Hazin, F.H., Hinton, M., Juan Jorda, M., Minte Vera, C., Miyabe, N., Montano Cruz, R., Masuti, E., Nelson, R., Oxenford, H., Restrepo, V., Salas, E., Schaefer, K., Schratwieser, J., Serra, R., Sun, C., Teixeira Lessa, R.P., Pires Ferreira Travassos, P.E., Uozumi, Y. & Yanez, E. 2011. Xiphias gladius. In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.2. <www.iucnredlist.org>. Downloaded on 18 April 2014.|
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