|Scope: Gulf of Mexico|
|Scientific Name:||Makaira nigricans Lacepède, 1802|
Eumakaira nigra Hirasaka and Nakamura 1947
Histiophorus herschelii (Gray 1838)
Istiompax howardi Whitley 1954
Istiompax mazara Jordan and Snyder 1901
Maikaira nigricans Lacepède 1802
Makaira ampla Poey 1860
Makaira ampla ampla Poey 1860
Makaira ampla mazara Jordan and Schneider 1901
Makaira bermudae Mowbray 1931
Makaira ensis Jordan & Evermann 1926
Makaira ensis Lacepède 1800
Makaira herschelii Gray 1838
Makaira nigra Hirasaka and Nakamura 1947
Makaira nigricans Poey 1860
Makaira nigricans mazara (Jordan and Snyder 1901)
Makaira perezi de Buen 1950
Tetrapturus amplus Poey 1860
Tetrapturus herschelii Grey 1838
Tetrapturus mazara Jordan and Snyder 1901
Blue Marlin (Makaira nigricans) of the Indo-Pacific and the Atlantic are conspecific (Buonaccorsi et al. 1999, 2001; Collette et al. 2006). The Indo-Pacific Blue Marlin previously was known as Makaira mazara (Jordan and Snyder).
|Red List Category & Criteria:||Endangered A2bd (Regional assessment) ver 3.1|
|Assessor(s):||Collette, B.B., Wells, D. & Abad-Uribarren, A.|
Based on the most recent stock assessment for Blue Marlin (ICCAT 2011) in the Atlantic Ocean, there has been an approximately 60% decline in estimated biomass over the past three generation lengths (14-18 years). Current biomass in the Atlantic is estimated to be at or below biomass at maximum sustainable yield (BMSY) and current fishing mortality rates are above FMSY, indicating the Atlantic stock is not considered to be well-managed. Although catches in U.S. waters are stable, Mexican landings have been increasing over the past 10 years. There is evidence of higher residency within the Gulf of Mexico compared to other billfishes, however, the status of this species is not considered to differ from the population in the broader western Atlantic. Therefore, it is listed as Endangered in the Gulf of Mexico under A2bd.
|Range Description:||An epipelagic oceanic species, blue marlin is often found in wide open blue waters with surface temperatures between 22° and 31°C. It is the most tropical of the billfishes. Its latitudinal range changes seasonally, expanding northwards and southwards in the warmer months and contracting towards the equator in colder months.|
In the Eastern Pacific it is found from California to the southwestern and central eastern Gulf of California to Peru, including all of the oceanic islands. In the Atlantic Ocean, adults are commonly found in the tropics within the 24°C isotherm.
In both the eastern tropical Pacific and the eastern tropical Atlantic, Blue Marlin concentrate in shallower waters than in the western part of both oceans due to hypoxia-based habitat compression over oxygen minimum zones in the eastern tropical seas (Prince et al. 2010).
Native:American Samoa; Angola; Anguilla; Antigua and Barbuda; Australia; Bahamas; Bangladesh; Barbados; Belize; Bermuda; Bonaire, Sint Eustatius and Saba; Brazil; Cameroon; Canada; Cape Verde; Chile; China; Christmas Island; Colombia; Comoros; Congo; Congo, The Democratic Republic of the; Cook Islands; Costa Rica; Côte d'Ivoire; Cuba; Dominica; Dominican Republic; Ecuador; El Salvador; Equatorial Guinea; Fiji; French Polynesia; Gabon; Gambia; Ghana; Grenada; Guadeloupe; Guam; Guatemala; Guinea; Guinea-Bissau; Haiti; Honduras; Hong Kong; India; Indonesia; Jamaica; Japan; Kenya; Kiribati; Korea, Republic of; Madagascar; Malaysia; Maldives; Marshall Islands; Mauritania; Mauritius; Mexico; Micronesia, Federated States of ; Montserrat; Mozambique; New Caledonia; New Zealand; Nicaragua; Nigeria; Niue; Norfolk Island; Northern Mariana Islands; Oman; Pakistan; Palau; Panama; Papua New Guinea; Peru; Philippines; Pitcairn; Portugal (Azores, Madeira); Puerto Rico; Réunion; Saint Barthélemy; Saint Helena, Ascension and Tristan da Cunha; Saint Kitts and Nevis; Saint Lucia; Saint Martin (French part); Saint Vincent and the Grenadines; Samoa; Sao Tomé and Principe; Senegal; Seychelles; Sierra Leone; Sint Maarten (Dutch part); Solomon Islands; Somalia; South Africa; Spain (Canary Is.); Sri Lanka; Taiwan, Province of China; Tanzania, United Republic of; Tokelau; Tonga; Trinidad and Tobago; Turks and Caicos Islands; Tuvalu; United States; United States Minor Outlying Islands; Vanuatu; Viet Nam; Virgin Islands, British; Virgin Islands, U.S.; Wallis and Futuna
|FAO Marine Fishing Areas:|
Atlantic – western central; Atlantic – southwest; Atlantic – southeast; Atlantic – eastern central; Atlantic – northeast; Atlantic – northwest; Indian Ocean – eastern; Indian Ocean – western; Mediterranean and Black Sea; Pacific – southeast; Pacific – eastern central; Pacific – western central; Pacific – southwest; Pacific – northeast; Pacific – northwest
The most recent stock assessment for Blue Marlin (ICCAT 2007) used a Bayesian Surplus Production model to estimate biomass from 1990 through 2006. The remaining data series (1956–1989) are based on biomass estimates from the previous stock assessment (ICCAT 2002). Population declines were examined using a generation length estimated between 4.5 and 6 years. Over a three generation length period of 14 years, the decline was 60% and over a three generation length period of 18 years, the decline was 64%. These declines were calculated using a linear regression over each of the time periods examined. Population reduction for Atlantic blue marlin was therefore estimated to be between 60% and 64%. For all of the models for which the stock productivity was constrained to be near the productivity estimated by the last full assessment, the current biomass was estimated to be at or below biomass at maximum sustainable yield (BMSY) and current fishing mortality rates were above FMSY. The stock is therefore not considered to be well-managed.
Based on the 2011 Blue Marlin Stock Assessment, declines in the Atlantic have not ceased, and B/Bmsy <1 and F/Fmsy>1, indicating no improvement in the Atlantic stock status. The largest catches reported in the Atlantic are from Japan, Chinese Taipei and Brazil (2012 ICCAT Blue Marlin Stock Assessment).
U.S. recreational fisheries manage this species with minimum size and limited landings of 250 individuals of Blue and While Marlin combined per year (ICCAT 2000). It has been prohibited from commercial fisheries in the United States since around the year 2000. In Mexico, it is mainly caught as by-catch in tuna fisheries. Catches reported from Mexico have been increasing over the past 10 years, from around 27 mt in 2000 to over 90 mt in 2010 (2012 ICCAT Blue Marlin Stock Assessment), and effort in the tuna long-line fishery has also increased over the past 10-15 years (A. Abad-Uribarren pers. comm. 2015). In Mexico, all catches of both Blue and White Marlin are kept (not discarded) (Plan de Manejo Pesquiero de Atun Alerta Amarilla en el Golfo de Mexico). Catches in Cuba and the U.S. are declining in both catch and discards over the last 10 years (2012 ICCAT Blue Marlin Stock Assessment), likely due to lack of resources in oil in Cuba and to increased regulation and changes in fishing practices in the U.S.
It appears that connectivity of this species in the Gulf of Mexico to Caribbean/Atlantic populations is likely lower than White Marlin based on otolith chemistry (Wells et al. 2010). Based on tagging data (Kraus et al. 2011), it seems to have higher residency within the Gulf of Mexico compared to other billfishes. Post-release survival is high (Kerstetter and Graves 2006, Graves and Horodysky 2008, Musyl et al. in press)
The best knowledge currently available indicates that Blue Marlin constitutes a single world-wide species (Buonaccorsi et al. 1999, 2001, Collette et al. 2006), and that there is a single stock of Blue Marlin in the Pacific Ocean (Hinton 2001). No recent estimates of biomass or catch per unit effort (CPUE) were available. Biomass estimates from the last stock assessment for Pacific Blue Marlin (Kleiber et al. 2003) were available only until 1997. We therefore used estimated catch data from the Inter-American Tropical Tuna Commission (IATTC) (Hinton, unpublished data 2011), which were the only available recent data. We assume that effort has remained stable or has increased over the time period examined. Based on catch data and a generation length of 4.5–6 years, we estimated declines of 5% over 14 years (1996–2009) and 19% over 18 years (1992–2009) using linear regression. We consider that these estimates of decline (based on catches) are likely conservative. This stock is not considered to be well-managed and there is urgent need for a newer stock assessment to evaluate population trends.
Nominal yearly CPUE of Japanese longliners in Northwest Australia has declined 58.9% over a 14 year period (1993–2007) and 70.6% over a 18 year period (1989–2007; Figure 40, IOTC 2009). The CPUE decline for Japanese longliners in the Seychelles was 79.5% over 14 years and 56.9% over 18 years (Figure 40, IOTC 2009). For each time period considered, an average of the declines in Northwest Australia and the Seychelles was used to characterize the population in the Indian Ocean. The decline in the Indian Ocean ranged from 63–69% depending on the time period considered. It is important to note that 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 blue marlin in the Indian Ocean.
|Current Population Trend:||Decreasing|
|Habitat and Ecology:||This epipelagic and oceanic species is mostly confined to the waters on the warmer side of the 24°C surface isotherm and known to undergo seasonal north-south migrations. It is found to 1,000 m depth but spends the highest percentage of its time at shallower depths, and is not usually seen close to land masses or islands, unless there is a deep drop-off of the shelf. This species can dive as deep as 1,000 m, but it remains mostly within the upper 40 m. It is believed to form small-scale schools of at most 10 individuals. Larger fish tend to swim solitarily (Nakamura 1985) but smaller ones form aggregations.|
It feeds on squids, tuna-like fishes, crustaceans, and cephalopods (Nakamura 1985). Spawning seems to peak in July in the northern Gulf of Mexico (Rooker et al. 2012). Spawning probably takes place year-round in equatorial waters to 10°N/S and during summer periods in both hemispheres to 30°N/S, in both the Indian and Pacific oceans (Kailola et al. 1993). In the southern hemisphere, concentrations of spawning fish probably occur around French Polynesia (Howard and Ueyanagi 1965). In Brazil, spawning occurs February to March from 20–23°S, primarily in the Abrolhos Archipelago (Amorim et al. 1998). Most of the individuals captured at this location have been juveniles (Amorim pers. comm. 2010).
Maximum time at large recorded is 11 years (Ortiz et al. 2003). Maximum age is estimated to be at least 20 years (Wilson et al. 1991). Maximum age is estimated in the Pacific as 27 years (females) and 18 years (males) (Hill et al. 1989). Age estimation in marlins is problematic and longevity information from the Pacific has also been applied to the Atlantic. Age at maturity is estimated to be two years (Prince et al. 1991, Torres-Silva et al. 2006). Using longevity estimates of 20 years and 27 years, and age of maturity of two years, the generation length was estimated to be between 4.5–6 years. 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).
The all-tackle game fish record is of a 636-kg fish caught off Vitoria, Brazil in 1992 (IGFA 2011).
|Generation Length (years):||4.5-6|
|Movement patterns:||Full Migrant|
|Use and Trade:||
Blue Marlin occurs as bycatch, primarily in longline fisheries for tuna. There is also a directed recreational catch for this species in many areas. The flesh is of good quality and is marketed frozen and prepared as sashimi and but most of it is marketed frozen or for sausages in Japan (Nakamura 1985).
In the Gulf of Mexico off Mexico, this species is taken as bycatch in fisheries targeting Thunnus albacares (SAGARPA 2012).
In the Pacific, Blue Marlin are an incidental catch of longline fisheries, bycatch in swordfish fisheries, and an important resource for big game recreational fishing. More than 73% of reported landings are incidental to large offshore longline fisheries, and other major fisheries are the directed recreational fisheries of the USA and other countries (Restrepo et al. 2003). Protections efforts for blue marlin have continued to decrease in recent years, as deeper longline gear is introduced (Uozumi 1999).
In the Atlantic, new fleets have harvested large catches of Blue Marlin, including artisanal fish aggregating devices (FAD) fisheries in the eastern Caribbean islands and a new artisanal fleet of small longliners operating off Brazil between 18°S and 30°S. This species is primarily taken as bycatch by longline fisheries, but also by purse seines, by some artisanal gears which are the only fisheries targeting marlins and also by various sport fisheries located on both sides of the Atlantic. The increasing use of anchored FADs by various artisanal and sport fisheries is causing greater vulnerability of these stocks (STECF 2009). For example, over the last fifteen years, Antillean artisanal fleets have increased the use of Moored Fish Aggregating Devices (MFADs) to capture pelagic fish. Catches of Blue Marlin caught around MFADs are known to be significant but reports on these catches made to the International Commission for the Conservation of Atlantic Tunas (ICCAT) are very incomplete (ICCAT 2006).
This is a highly migratory species, listed under Annex I of the 1982 Convention on the Law of the Sea (FAO Fisheries Department 1994).
In some areas, long-lining is restricted to protect fish stocks for sport fishing. Size limitations, encouragement of catch-and-release sport fishing, and recommendations for using circle hooks instead of J-hooks are measures designed to increase survival in catch-and-release sport fishing (Pine et al. 2008, Serafy et al. 2009). Marlin species are a special case because bycatch in the longline fisheries concentrating primarily on tunas causes the majority of fishery mortality (>90%) for marlin (Kitchell et al. 2004). In the Pacific, marlin are most frequently captured on the shallow hooks of a longline set (those close to the floats), and removing less than 15% of the hook sets adjacent to floats would decrease marlin catch by as much as 50% (Kitchell et al. 2004).
For Blue Marlin in the Atlantic, the ICCAT Standing Committee on Research and Statistics (ICCAT–SCRS) in 2008 asked the Commission, at a minimum, to continue the management measures already in place because marlins have not yet recovered. The Commission should take steps to assure that the reliability of the recent fishery information improves in order to provide a basis for verifying possible future rebuilding of the stocks. Improvements are needed in the monitoring of the fate and number of dead and live releases, with verification from scientific observer programs; verification of current and historical landings from some artisanal and industrial fleets; and complete and updated relative abundance indices from CPUE data for the major fleets. Should the Commission wish to increase the likelihood of success of the current management measures of the marlin rebuilding plan, further reduction in mortality would be needed, including: implementing plans to improve compliance of current regulations; encouraging the use of alternative gear configurations, including certain types of circle hooks, hook/bait combinations etc., in fisheries where its use has been shown to be beneficial; and broader application of time/area catch restrictions.
In the Atlantic Ocean, unless the current catch levels (3,431 t, 2010) are substantially reduced, the stock will likely continue to decline. The Commission should adopt a rebuilding plan for the stock of Atlantic Blue Marlin (2011 ICCAT Blue Marlin Stock Assessment).
Given the recent importance of the catch from artisanal fisheries, and to increase the likelihood of recovery of marlin stocks, the Commission should consider regulations that control or reduce the fishing mortality generated by these fisheries. The Commission should encourage continued research on development of methods to incorporate this information into stock assessments in order to provide a basis for increasing the certainty with which management advice can be provided.
The Scientific, Technical and Economic Committee for Fisheries (STECF) stresses the need for correct identification and reporting of billfish species in all fisheries. Furthermore, STECF notes that the 2007 ICCAT–SCRS report indicated the potential for the stocks of blue marlin and white marlin to recover to the BMSY level. However, recent increases in catches of Blue Marlin by artisanal fisheries on both sides of the Atlantic may compromise the effectiveness of the ICCAT plan (STECF 2009).
Recent analyses suggest that the recovery of blue marlin stock might proceed faster than would have been estimated at the 2000 assessment, provided catches remain at the level estimated for 2004. Some signs of stabilization in the abundance trend are apparent in the most recent catch per unit of effort data of Blue Marlin (2000–2004) Recommendations [Rec. 00-13], [Rec. 01-10] and finally [Rec. 02-13] placed additional catch restrictions for Blue Marlin and White Marlin. The first established that the annual amount of Blue Marlin that can be harvested by pelagic longline and purse seine vessels and retained for landing must be no more than 33% for White Marlin and 50% for Blue Marlin of the 1996 or 1999 landing levels, whichever is greater. That recommendation established that all Blue Marlin and White Marlin brought to pelagic longline and purse seine vessels alive shall be released in a manner that maximizes their survival. The provision of this paragraph does not apply to marlins that are dead when brought along the side of the vessel and that are not sold or entered into commerce. Catches of both species have declined since 1996–99, the period selected as the reference period by the recommendations. Since 2002, the year of implementation of the last of these two recommendations, the catch of Blue Marlin has been below the 50% value recommended by the Commission. This analysis represents only longline caught marlin even though the recommendations referred to the combined catch of pelagic longline and purse seine because the catch estimates of billfish by-catch from purse seine vessels are more uncertain than those from longline. More countries have started reporting data on live releases in 2006. Additionally, more information has come about, for some fleets, on the potential for using gear modifications to reduce the bycatch and increase the survival of marlins (ICCAT 2007).
Catches of Blue Marlin in the Indian Ocean are very poorly reported and there is need of better data to evaluate the condition of the Indian Ocean stock.
|Citation:||Collette, B.B., Wells, D. & Abad-Uribarren, A. 2015. Makaira nigricans. The IUCN Red List of Threatened Species 2015: e.T170314A76596659.Downloaded on 21 June 2018.|
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