|Scientific Name:||Isurus oxyrinchus|
|Species Authority:||Rafinesque, 1810|
|Infra-specific Taxa Assessed:|
|Red List Category & Criteria:||Vulnerable A2abd+3bd+4abd ver 3.1|
|Assessor/s:||Cailliet, G.M., Cavanagh, R.D., Kulka, D.W., Stevens, J.D., Soldo, A., Clo, S., Macias, D., Baum, J., Kohin, S., Duarte, A., Holtzhausen, J.A., Acuña, E., Amorim, A. & Domingo, A.|
|Reviewer/s:||Fowler, S.L., Dudley, S., Soldo, A., Francis, M. & SSG Pelagic Shark Red List Workshop participants (Shark Red List Authority)|
Shortfin Mako (Isurus oxyrinchus) is an important target species, a bycatch in tuna and billfish longline and driftnet fisheries, particularly in high-seas fisheries, and is an important coastal recreational species. Most catches are inadequately recorded and underestimated and landings data do not reflect numbers finned and discarded at sea. Various analyses suggest that this species may have undergone significant declines in abundance over various parts of its range. A global assessment of Vulnerable is considered appropriate for this species on the basis of estimated and inferred declines, inadequate management resulting in continuing (if not increasing) fishing pressure, the high value of its meat and fins, and vulnerable life history characteristics. Although it is difficult to accurately assess the conservation status of this shark because it is migratory and caught in numerous poorly monitored fisheries worldwide, it is reasonable to assume that decreases may be occurring in those areas for which there is limited or no data.
Several subpopulations of Shortfin Mako have been assessed separately for the IUCN Red List, however further data are required to determine whether individuals occurring in the Mediterranean constitute a subpopulation (based on the definition of "subpopualtion" as given in the IUCN Red List Categories and Criteria). Recent investigations in the Mediterranean suggest that the western basin is a nursery area where bycatch of Shortfin Mako (Isurus oxyrinchus) from the tuna and swordfish fishery consists almost exclusively of juveniles. It is possible that this nursery area corresponds to the Eastern Central Atlantic population, which is affected by the swordfish longline fishery off the western coast of Africa and the Iberian peninsula. In other areas of the Mediterranean, the Shortfin Mako is caught sporadically. Reports from the Ligurian Sea show a significant decline since the 1970s. In the Adriatic Sea, Shortfin Makos were considered common at the end of 19th/beginning of the 20th centuries, but since 1972 there have been no records of this species reported despite a large increase in fishing pressure and introduction of new fishing gear to the area. On the basis of the absence of records of this species from some localised areas, evidence of large declines in others and captures of juveniles in a probable nursery area, this species is considered Critically Endangered in the Mediterranean, warranting focused attention and immediate action in order to preserve this species in the region.
|Range Description:||Shortfin Mako is a coastal, oceanic species occurring from the surface to at least 500 m depth and is widespread in temperate and tropical waters of all oceans from about 50°N (up to 60°N in the northeast Atlantic) to 50°S. It is occasionally found close inshore where the continental shelf is narrow. It is not normally found in waters below 16°C (Compagno 2001).
Summary of range
Western Atlantic: Grand Banks (Canada) to Uruguay and northern Argentina, including Bermuda, Gulf of Mexico and Caribbean. Eastern Atlantic: Norway, British Isles and Mediterranean to Morocco, Azores, Western Sahara, Mauritania, Senegal, Côte d?Ivoire, Ghana, southern Angola, probably Namibia, and South Africa (west coast).
Indo-West Pacific: South Africa (east coast), Mozambique, Madagascar, Mauritius and Kenya north to Red Sea and east to Maldives, Iran, Oman, Pakistan, India, Indonesia, Viet Nam, China, Taiwan (Province of China), North Korea, South Korea, Japan, Russia (Primorskiyi Kray), Australia (all states and entire coast except for Arafura Sea, Gulf of Carpentaria and Torres Strait), New Zealand (including Norfolk Island), New Caledonia, Fiji. Central Pacific: From south of Aleutian Islands to Society Islands, including Hawaiian Islands. Eastern Pacific: USA (Southern California and exceptionally Washington), south to Mexico, Costa Rica, Ecuador, Peru and central Chile.
In addition to the distribution given in Compagno (2001), Shortfin Mako may also occur from 20?50° between Australia and Chile, and to almost 60° Southeast of New Zealand (Yatsu 1995, M. Francis pers. comm. 2006).
Casey and Kohler (1992) suggest that the core distribution in the western north Atlantic is between 20?40°N, bordered by the Gulf Stream in the west and the mid-Atlantic ridge in the east (see Habitat and Ecology section for more details). Shortfin Mako in Atlantic Canadian waters represent the margins of the distribution of the population (Campana et al. 2005). In the eastern North Atlantic, it is presumed that the Strait of Gibraltar is nursery (Buencuerpo et al. 1998 and Tudela et al. 2005).
The area between 17° to 35°S off the coast of Brazil is an area of birth, growth and mating (Amorim et al. 1998). Pregnant females with near term embryos have been found there, but not females in early pregnancy stages (Costa et al. 1995, Costa 1994). The presence of this species in Uruguayan waters year round has been confirmed by the observers on board the Uruguayan tuna fleet. Although a few new borns were captured, no pregnant females have been found (Domingo pers. comm. 2008).
Highest abundance is reported in the western Mediterranean and mako are rarely reported in eastern waters (Aegean Sea and Sea of Marmara). Recent investigations suggest that the western basin is a nursery area (Buencuerpo et al. 1998). It is possible that this nursery area is from the eastern central Atlantic population, which is affected by the swordfish longline fishery off the western coast of Africa and Iberian peninsula. Two Shortfin Makos a few months old were reported in the western Ligurian Sea as bycatch of the swordfish longline fishery (Orsi Relini and Garibaldi 2002). They are not reported from the Black Sea. In the eastern Adriatic Sea, Shortfin Makos were reported as common a century ago (Katuri 1893 and Kosi 1903), recent publications consider it to be rare (Mili?i? 1994, Jardas 1996). Soldo and Jardas (2002) report that there have been no records of Shortfin Mako in the eastern Adriatic since 1972.
Eastern North Pacific
There are comparatively few records of pregnant females, especially in the eastern north Pacific. However, there are a large number of juveniles and young of the year fish in the southern California Bight indicating that it is a nursery area. In summer, the Southern California Bight is home to a large population of Shortfin Mako sharks (Klimley et al. 2002, Holts and Kohin 2003). Abundance surveys and fishing reports indicate that juvenile mako sharks appear in the Bight in spring when water temperatures rise above 16°C and may depart from the area in fall when water temperatures decline.
Native:Albania; Algeria; Angola (Angola); Anguilla; Antigua and Barbuda; Argentina (Buenos Aires, La Pampa); Australia (Ashmore-Cartier Is., Australian Capital Territory, Coral Sea Is. Territory, Lord Howe Is., Macquarie Is., New South Wales, Northern Territory, Queensland, South Australia, Tasmania, Victoria, Western Australia); Bahamas; Bangladesh; Barbados; Belize; Benin; Bermuda; Brazil (Bahia, Brasília Distrito Federal, Minas Gerais, Pará, Rio de Janeiro, São Paulo); Brunei Darussalam; Cambodia; Cameroon; Canada (British Columbia, Newfoundland I, Nova Scotia); Cape Verde; Cayman Islands; Chile; China; Colombia (Colombia (mainland), Colombian Caribbean Is.); Congo; Cook Islands (Cook Is.); Costa Rica; Côte d'Ivoire; Croatia; Cuba; Curaçao; Cyprus; Dominica; Dominican Republic; Ecuador (Ecuador (mainland), Galápagos); Egypt; El Salvador; Equatorial Guinea (Equatorial Guinea (mainland)); Eritrea; Fiji; France (Clipperton I., Corsica, France (mainland)); French Guiana; French Polynesia (Marquesas, Society Is., Tuamotu, Tubuai Is.); Gabon; Gambia; Ghana; Gibraltar; Greece (East Aegean Is., Kriti); Grenada; Guadeloupe; Guatemala; Guinea; Guinea-Bissau; Guyana; Haiti; Honduras (Honduran Caribbean Is., Honduras (mainland)); India (Andaman Is., Andhra Pradesh, Kerala, Maharashtra, Nicobar Is., Orissa, Pondicherry); Indonesia (Bali, Irian Jaya, Jawa, Kalimantan, Lesser Sunda Is., Maluku, Sulawesi, Sumatera); Iran, Islamic Republic of; Ireland; Israel; Italy (Italy (mainland), Sardegna, Sicilia); Jamaica; Japan (Hokkaido, Honshu, Kyushu, Nansei-shoto, Shikoku); Kenya; Kiribati; Korea, Democratic People's Republic of; Korea, Republic of; Liberia; Libya; Macao; Madagascar; Malaysia (Peninsular Malaysia, Sabah, Sarawak); Maldives; Malta; Marshall Islands; Martinique; Mauritania; Mauritius (Mauritius (main island)); Mexico (Baja California, México State, Veracruz, Yucatán); Micronesia, Federated States of ; Montenegro; Montserrat; Morocco; Mozambique; Myanmar (Coco Is., Myanmar (mainland)); Namibia; Nauru; Netherlands Antilles (Bonaire, Netherlands Leeward Is.); New Caledonia; New Zealand (Antipodean Is., Chatham Is., Kermadec Is., North Is., South Is.); Nicaragua (Nicaragua (mainland), Nicaraguan Caribbean Is.); Nigeria; Northern Mariana Islands; Norway; Oman; Pakistan; Palau; Panama; Papua New Guinea; Peru; Philippines; Pitcairn; Portugal (Azores, Madeira, Portugal (mainland)); Puerto Rico (Puerto Rico (main island)); Russian Federation (Primoryi); Saint Kitts and Nevis; Saint Lucia; Saint Vincent and the Grenadines; Samoa; Saudi Arabia; Senegal; Sierra Leone; Singapore; Solomon Islands (Santa Cruz Is., South Solomons); Somalia; South Africa (Eastern Cape Province, KwaZulu-Natal, North-West Province, Western Cape); Spain (Baleares, Canary Is., Spain (mainland), Spanish North African Territories); Sri Lanka; Sudan; Suriname; Taiwan, Province of China (Taiwan, Province of China (main island)); Tanzania, United Republic of; Thailand; Timor-Leste; Tonga; Trinidad and Tobago; Tunisia; Turkey; Turks and Caicos Islands; Tuvalu; United Kingdom (Great Britain, Northern Ireland); United States (Aleutian Is., Arizona, California, Connecticut, Delaware, District of Columbia, Florida, Georgia, Hawaiian Is., Louisiana, Maine, Maryland, Massachusetts, Mississippi, Nebraska, New Hampshire, New Jersey, New Mexico, New York, North Carolina, Oregon, Rhode Island, South Carolina, Texas, Virginia, Washington); Uruguay; Vanuatu; Venezuela, Bolivarian Republic of (Venezuela (mainland), Venezuelan Antilles); Viet Nam; Virgin Islands, British; Virgin Islands, U.S.; 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.|
Shortfin Mako contribute some 9.5?10% of the pelagic sharks caught by Spanish longline fleets (targeting sharks and swordfish) in the Atlantic and Pacific Oceans (Mejuto et al. 2002, 2005, 2006, 2007).
Shortfin Mako in the north and the south Atlantic constitute genetically distinct groups (Heist et al. 1996). Casey and Kohler (1992) hypothesized from tag-recapture data that western north Atlantic makos form a separate population from those in the eastern Atlantic although limited intermixing is possible as shown by crossings to the Azores and Europe. Mitochondrial DNA data indicate separation of female makos between the western and eastern north Atlantic, but a lack of differentiation in nuclear DNA suggests male mixing across the north Atlantic (Heist et al. 1996, Schrey and Heist 2003). For fishery assessment purposes, mixing between the western and eastern North Atlantic is considered minimal.
Mature males were occasionally caught in the western English Channel in the 1960s and 1970s but are now rarely encountered (J. D. Stevens, pers. comm.), suggesting possible range contraction in the north-east Atlantic.
Analyses of catch per unit effort (CPUE) from US pelagic longline fishery logbooks reported that Isurus spp. may have declined by about 40% in the northwest Atlantic between 1986 and 2000 (Baum et al. 2003). A more recent assessment of observer data for the same fishery found a similar instantaneous rate of decline of 38% between 1992 and 2005 (Baum et al. in prep). A similar analysis of the same dataset and species grouping that restricted the areas of analysis to account for unbalanced observations, resulted in an overall decline of 48% from beginning to end of the time series (1992-2005; Cortes et al. in press). A 2004 ICCAT stock assessment workshop reported that stock depletions for north Atlantic Shortfin Mako are likely to have occurred based on CPUE declines of 50% or more. Demographic model results varied widely, with one approach suggesting present stock size is about 80% of virgin level, and another approach suggesting reductions to about 30% of virgin biomass (1950s) (Cortes et al. in press).
In the South Atlantic, the magnitude of decline appears to be smaller than in the north Atlantic and the stock size appears to lie above MSY, although only one modeling approach could be applied to the available data and assessments results were more uncertain than for the North Atlantic.
For both north and south Atlantic populations, uncertainties about demographic parameters and catches, and the uninformative nature of available catch data indicate that further analysis is necessary to properly delineate stock status. If historical Shortfin Mako catch is higher than the estimates in this report, the likelihood of the stock being below the biomass at MSY will surely increase (ICCAT 2005). A standardized catch rate index from the commercial large pelagic fishery off Canada suggested a decline in the 1970s and stable abundance since 1988 (Campana et al. 2005). However, the analysis did not have the statistical power to detect anything less than a severe decline and these sharks represent the margins of the population. The most heavily fished areas lie outside of Canadian waters. The median size of mako sharks in the commercial catch has declined since 1988, possibly indicating a loss of larger sharks (Campana et al. 2005).
Off Brazil, the highest and lowest catches of shortfin mako from Santos longliners were 235 and 29 t from 1971?2001. The CPUE and average weight decreased from 4.5 to 4.1 kg/1,000 hooks and 60 to 37.3 kg respectively (Amorim et al. 2002). About 20 t/yr were caught by gillnetters in southern Brazil between 1993?94 (Jorge Kotas, pers comm, CEPSUL-IBAMA, Brazil). The unstandardised CPUE in the Uruguayan longline fleet was low and stable (average 35 kg/1,000 hooks) from 1983 to 1998 and has increased steadily to 2004 (185 kg/1,000 hooks), lower in 2005 (90 kg/1000 hooks) (ICCAT data). According to Mourato et al. (in press), based on the landings records and logbooks from the Sao Paulo fleet operating off Southern Brazil, the standardized CPUE for the period 1971-2006 was fluctuating but showed a slight decline. In contrast, the standardization of the CPUE of 29 years in the Brazilian tuna longline fleet showed a slight upward trend (Hazin et al. in press). In Uruguay, the total captures oscillated through the years, mainly in low values (8 to 21 tons per year), and reached maximum values in 2003?2005 (up to 200 tons per year) (Domingo 2002, Domingo et al. 2008). The standardization of the mako shark CPUE in the Uruguayan pelagic longline fleet for the period 1981?2006 show a slight increase between 1989 and 2003, and a decreasing trend towards 2006 (Pons and Domingo in press).
In the Mediterranean, ?Tonnarella? (tuna-trap) catches in the Ligurian Sea from 1950 to the 1970s show a rapid decline and eventual disappearance of the Shortfin Mako (Boero and Carli 1979). Landings data from Maltese waters for 1979?2001 (data from the Maltese fishery department) shows a decline although the fishing pressure was not changed. Historically described as common (end of 19th/beginning of 20th century), Soldo and Jardas (2002) report that there have been no records of Shortfin Mako in the eastern Adriatic since 1972. Since 1998, there have been few records of mako sharks from the central and eastern Mediterranean (A. Soldo pers. comm.). Previously, the species was considered common throughout the Mediterranean.
In the eastern north Pacific, tagging studies have been carried out by the California Department of Fish and Game (Anon. 2001), and more recently by the National Marine Fisheries Service, Southwest Fisheries Science Center (Holts and Kohin 2003, Holts et al. 2004). Using a consistent sample size of 28 sets of 200 hooks during each of eight years (1994?1997, 2000?2003), CPUE data showed a slight decline (Holts et al. (2004); y = -0.0696x + 1.0982, R2 = 0.5107). However, it does not appear to be sufficient to warrant serious concern about the population. The large horizontal (primarily north-south along the coastline, but with some inshore-offshore movements) (Holts et al. 2004) and vertical (up to ~500 m) (Holts and Kohin 2003, Sepulveda et al. 2004) movements of Shortfin Makos, a behaviour that could make them more or less available to the gear spatially but not necessarily indicating a population decline. Likewise, for males and females, there appeared to be a slight increase in the average size caught over the same eight years (y = 1.8368x + 112.38, R2 = 0.3751). This, combined with the CPUE changes would suggest that the biomass indices had not changed. The variability among years in CPUE can also be attributed to inter-annual oceanographic and climate changes, especially water temperature (http://www.pcouncil.org/hms/hmsback.html). Thus, although there are no precise or accurate population estimates, it appears that the population of shortfin makos in the eastern North Pacific has been relatively stable. (Taylor and Holts 2001, PFMC 2003).
|Habitat and Ecology:||
Habitat and movements
The Shortfin Mako is an active, offshore littoral and epipelagic species, found in tropical and warm-temperate seas from the surface down to at least 500 m, seldom occurring where water temperature is <16°C (Compagno 2002). It is probably the fastest shark and is among the most active and powerful of fishes. Like other lamnid sharks, the Shortfin Mako is endothermic using a heat-exchanging circulatory system to maintain muscle and visceral temperatures above that of the surrounding seawater allowing a higher level of activity (Carey et al. 1981, Bernal et al. 2001). This shark occurs well offshore but penetrates the inshore littoral just off the surf zone in some areas such as parts of KwaZulu-Natal, South Africa where the continental shelves are narrow. Off South Africa, shark meshing data suggests that this species occurs in clear to turbid water in water temperatures from 17?22°C. In the western north Atlantic it occurs in a similar range of temperatures, and only moves onto the continental shelf when surface temperatures exceed 17°C. In the eastern north Pacific, juveniles range into southern Californian waters and tend to be seen and caught near the surface. They appear to use these offshore continental waters as nursery areas (Taylor and Holts 2001). It was previously thought that they stay near the surface above 20 m depth, in waters between 20?21°C, seldom descending into cold subsurface waters below the thermocline (Holts and Bedford 1992). However, this has been challenged by more recent tracking studies (summarized below).
Results from a large tagging study in the western north Atlantic show that Shortfin Makos make extensive movements of up to 3,433 km with 36% of recaptures caught at greater than 420 km from their tagging site (Casey and Kohler 1992). However, only one fish crossed the mid-Atlantic ridge suggesting that trans-Atlantic migrations are not as common as in blue sharks Prionace glauca. Klimley et al. (2002) tracked three shortfin makos near La Jolla, California, for several days, and their movements were mainly offshore from the surface to 50 m. Holts and Kohin (2003) deployed pop-up archival tags on eight makos (118?275 cm TL) in June?July 2002 for 2?4 months. Pop-up locations ranged from 20?911 km from deployment locations. The sharks utilized near-shore and open-water areas off California and Baja California roughly between 23?43°N and out to 125°W. While the records indicate that greater than 90% of the time was spent above 50 m, several sharks showed a diurnal pattern of vertical excursions to beyond 200 m during daylight hours. Sharks frequently dove into water less than 10°C. These data demonstrate the range of habitats utilized by mako sharks and begin to shed light on their daily and seasonal behaviours. Sepulveda et al. (2004) found that seven tagged juveniles stayed near the surface at night, and went as deep as 200 m, mostly during the day. In addition, stomach temperatures were measured, indicating feeding occurred during the daytime, with meals taken during a dive causing stomach temperatures to drop noticeably.
Life History Parameters
The Shortfin Mako reaches a maximum size of about 4 m (Compagno 2001). Initial age and growth studies in the western north Atlantic suggested that two pairs of growth bands are laid down each year in their vertebral centra, at least in young shortfin makos (Pratt and Casey 1983). However, recent evidence using marginal increment analysis in Mexico (Ribot-Carballal et al. 2005) and bomb radiocarbon (Campana et al. 2002, Ardizzone et al. 2006) indicates that the alternative hypothesis (one pair of growth bands per year; Cailliet et al. 1983) is valid. Age at maturity has been determined recently in several populations, including New Zealand (7?9 years for males, and 19?21 years for females Bishop et al. (2006)), and the western north Atlantic (eight years for males, and 18 years for females (Natanson et al. 2006)). Longevity has been estimated as 29?32 years (Bishop et al. 2006, Natanson et al. 2006).
There is a large difference in size at sexual maturity between the sexes. In the northwest Atlantic, males reach maturity at about 195 cm and females at about 265?280 cm (Pratt and Casey 1983, Stevens 1983, Cliff et al. 1990). In New Zealand, males mature at 198?204 cm and females at 301?307 cm (Francis and Duffy 2005). Compagno (2001) reports males mature between 203?215 cm, reaching a maximum size of 296 cm, and females mature between 275?293 cm, reaching a maximum of almost 4 m.
The Shortfin Mako is ovoviviparous and oophagous, but what little is known of its reproductive cycle indicates the gestation period is 15?18 months, with a three year reproductive cycle (Mollet et al. 2002). Litter size is 4?25 pups (possibly up to 30, mostly 10?18), which are about 60?70 cm long at birth (Garrick 1967, Compagno 2001). There are comparatively few records of pregnant females. Among 26 shark species, the Shortfin Mako has an intrinsic rebound potential (a measure of its ability to recover from exploitation) in the mid-range (Smith et al. 1998). The annual rate of population increase is 0.046 yr-1 (S. Smith pers. comm.) Cortes (2002) calculated a finite rate of increase (lambda) of 1.141 (1.098 to 1.181 95% CI, r = 0.13) and the average reproductive age as 10.1 (9.2 to 11.1 95% CI) years.
The diet of Shortfin Makos has been reported to consist mainly of teleost fishes (including mackerels, tunas, bonitos and other scombrids, anchovies, herrings, grunts, lancet fishes, cod, ling, whiting and other gadids, salmon, yellowtails and other carangids, sea basses, porgies, swordfish) and cephalopods in studies from the northwest Atlantic and Australia (Stillwell and Kohler 1982, Stevens 1984), while elasmobranchs were the most common prey category from Natal, South Africa (Cliff et al. 1990). A daily ration of 2 kg/day (based on an average weight of 63 kg) was estimated for makos in the northwest Atlantic (Stillwell and Kohler 1982). Large makos (over 3 m in length) have very broad, more flattened and triangular teeth, perhaps better suited to cutting large prey than the awl-shaped teeth of smaller individuals (Compagno 1984a). There are several anecdotal accounts of makos attacking and consuming Broad-bill Swordfish Xiphias gladius. It also eats sea turtles, dolphins, salps and occasionally detritus (Compagno 1984a).
The Shortfin Mako is an important species for pelagic longline, drifting or set gill nets and on hook-and-line fisheries wherever it occurs, particularly from nations with high seas fleets (Holts et al. 1998), because of its relatively high abundance (9.5?10% of pelagic sharks caught in Spanish long line fleets (Mejuto et al. 2002, 2005, 2006, 2007) and high quality meat. It is taken as a bycatch from tuna and swordfish longline fisheries worldwide, with carcasses and fins being retained. Big-game sports angling for mako sharks is widespread, New Zealand and South Africa being traditional places for offshore sports fishing. The International Game Fish Association lists the shortfin mako as a record game fish. In the 1980s mako angling became popular in the USA off southern California, with numerous anglers involved and mako tournaments rivaling competitive angling for marlin (Compagno 2001). Recreational fishing has also been reported in the Mediterranean, although there are no official data (A. Soldo pers. comm.).
Fisheries for Shortfin Mako exist or existed in the eastern Atlantic, the Mediterranean Sea, off Cuba, in the Gulf of Mexico and Caribbean, off southern California, and in the western and central Pacific (Compagno 2001). This is also a target of pelagic swordfish fisheries in the Atlantic and Pacific (Mejuto et al. IBID).
Despite the role of Shortfin Makos in worldwide pelagic fisheries, catches have been poorly reported to FAO. Catch data are incomplete, and the extent of finning in high seas fisheries is unclear. Brazil, New Zealand and the United States reported very small catches (2?76 t) to FAO from 1987?1997 (FAO FishStat Plus database 2000). Although it is difficult to accurately assess the conservation status of this shark because it is migratory and caught in numerous poorly monitored fisheries worldwide, it is reasonable to assume that decreases may be occurring in those areas for which there are limited or no data (Castro et al. 1999).
Shortfin Makos have been caught in large numbers particularly on the high seas in pelagic longline fisheries, but also in other commercial pelagic fisheries and recreational fisheries. The first longline fisheries were prosecuted by Japan in western equatorial waters beginning in 1956 (Uozumi and Nakano 1996). The fleet expanded rapidly in the 1960s, and covered almost the entire Atlantic by the late 1960s (Bonfil 1994), including the areas currently fished by the American fleet. Throughout the Atlantic, the fleet landed mako sharks and fins (Nakano 1993). In the US and Canadian pelagic longline fisheries, Shortfin Mako is one of the most commonly caught sharks. The index of abundance in the commercial longline fishery off the Atlantic coast of US has shown a steady decline (Cramer 1996) and other reports on declines are now available (Baum et al. 2003, Baum et al., in prep, ICCAT 2005, Cortes et al. in press: see Population section for details). As for recreational fishing, Casey and Hoey (1985) stated that the recreational catch of Shortfin Makos along the US Atlantic coast and in the Gulf of Mexico in 1978 was 17,973 fish weighing some 1,223 t. Between 1987 and 1989, the catch was about 1000 t/year (Casey and Kohler 1992) taken by longline and gillnet in the Southwest Atlantic (see Population section). Shortfin Mako shark is a high value bycatch of pelagic longline fisheries on the Atlantic coast of Canada and therefore retained (Campana et al. 2005).
In 1989, Bonfil (1994) estimated that 5,932 Shortfin Makos were caught by Korean longliners in the (mainly equatorial) Atlantic and that 763 t of makos were landed in the Spanish swordfish fishery in the Mediterranean and Atlantic. Mejuto (1985) noted that 304?366 t of mako shark was landed by longliners operating from northern Spain in 1983?84. More recently, shortfin mako sharks have comprised about 7% (~2,500 t) of the total catch of the large Spanish pelagic longline swordfish fleet in the Atlantic (Mejuto et al. 2005). Munoz-Chapuli et al. (1993) estimated that some 4,500 makos/year are landed from a longline fishery based at Algeciras, southern Spain (given an average weight of 20 kg this would represent about 90 t). The landings of Shortfin Makos as bycatch from the swordfish fishery of the Azorean fleet also showed a decrease (Castro et al. 1999). Shortfin Mako landings reported to ICCAT from Portuguese surface longline fisheries in the north Atlantic averaged about 698 t during 1993?1996 and 340 t for the period 1997?2002. Off Namibia, the large pelagic fisheries caught an estimated 123 t in 2001, 399 t in 2002 and 393 t in 2003 by means of pelagic longline. The 2001 catch is an underestimate as many boats grouped different shark species as ?sharks? (MFMR catch data). Domingo (2002) records high catches of Shortfin Makos by the Uruguayan fleet in the early-mid 1980s (to a maximum of 144 t in 1984), followed by much lower catches (10?20 t/annum) in the 1990s. This does not necessarily reflect stock abundance because changes in the distribution and depth of fishing operations and rising mean temperature of water masses in the area had also occurred.
It has been estimated that in the early 1990s, the Spanish longline fleet caught approximately 750 t/y of Shortfin Mako sharks in the Atlantic Ocean and Mediterranean Sea (Bonfil 1994, Compagno 2001). The Brazilian longlining fleet based in Santos landed between 13.3 and 138.3 t annually between 1971 and 1990 (Costa et al. 1996, Compagno 2001). Despite increasing fishing effort during this period, the CPUE of Shortfin Makos has remained relatively stable with an initial slight decreasing trend followed by a slight increasing trend (Compagno 2001).
No complete data are available for the northeast Atlantic, but the species is taken as a bycatch of the pelagic fishery. The area around the Strait of Gibraltar is considered a nursery area for central Atlantic Shortfin Makos and most specimens caught are juveniles. This area is heavily fished by the swordfish longline fishery off the western coast of Africa and Iberian peninsula. There is also evidence that Shortfin Makos are becoming increasingly targeted in the western Mediterranean. EU vessels fishing for small pelagic species off the western coast of Africa are also known to take significant elasmobranch bycatch, including Shortfin Makos in unknown numbers.
Reports of ?Tonnarella? catches in the Ligurian Sea from 1950 until the 1970s show a rapid decline and eventual disappearance of the Shortfin Mako (INP 2000). Recent investigations of the shortfin mako bycatch from the swordfish longline fishery in the western basin show that catches from this fishery consist almost exclusively of juveniles. It is likely that the western Mediterranean is a nursery area for the eastern Central Atlantic population Soldo and Jardas (2002) report that there have been no records of shortfin mako in the eastern Adriatic since 1972 (where they were historically common).
Even though driftnetting is banned in Mediterranean waters, this practise has continued illegally (WWF 2005). The Moroccan swordfish driftnet fleet in the Alboran Sea operates year round, resulting in high annual effort levels (Tudela et al. 2005). Even though sharks are a secondary target or bycatch of this fishery, some boats deploy driftnets 1?2 miles from the coast where the chance of capturing pelagic sharks is higher. The catch rate for Shortfin Mako is nearly three times higher in boats actively fishing for sharks (from 0.6 to 1.9 N/fishing operation and 0.06 to 0.14 catch per km net). Both annual catches and mean weights of shortfin mako have fallen as a result of fishing mortality in the Moroccan driftnet fishery, illustrating the likely impact of this illegal fishery on stocks in the Alboran Sea and adjacent Atlantic (Tudela et al. 2005).
Megalofonou et al. (2005) reported 321 specimens caught as bycatch in tuna and swordfish fisheries in the Mediterranean Sea. Of those, 268 specimens were caught in Alboran Sea, 42 in Balearic Islands area, three in Catalonian Sea, while only eight specimens were caught in central and eastern Mediterranean area, e.g., Levantine basin. Furthermore, most of caught specimens were juveniles, with only a few large specimens from Levantine basin. Of 595 specimens caught in south Spain waters all of them were immature juveniles (Buencuerpo et al. 1998). Reports from the Ligurian Sea show a significant decline since the 1970s (Boero and Carli 1979).
Estimates of mako bycatch in various gillnet fisheries in the north Pacific are given in Bonfil (1994). Bycatch in the Japanese salmon fishery in 1989 was about 15 t, and about 63 t was taken in the squid fishery in 1990. In the Japanese large-mesh driftnet fishery in the South Pacific, about 286 t of Shortfin Mako was caught in 1990. The Spanish pelagic longline fishery for swordfish and sharks is expanding rapidly in the Pacific. Shortfin Makos comprise about 5% (~600?700 t) of the total catch of this fleet (Mejuto et al. 2007).
Reported average catch rates for Shortfin Makos vary from 0.3?3.4 sharks per 1,000 hooks (Stevens and Wayte 1999). Stevens (in press) used stratified catch rates in conjunction with fishing effort and average weights to estimate a catch of 4,100 t caught by high-seas longlining in the Pacific in 1994. Longline fleets take about 100?200 t from around New Zealand each year (Ministry of Fisheries Science Group 2006) and about 100 t were taken in Australian EEZ waters by Japanese tuna vessels each season (Stevens and Wayte 1999).
A coastal driftnet fishery for juvenile Shortfin Mako shark developed during the late 1970s in California; landings reached 242 t in 1982, fluctuated between 102-278 t from 1983?91 and declined to less than 100 t after 1991 (Holts et al. 1998). An experimental coastal longline fishery targeting makos took between 50 and 120 t annually during 1988?91 before the fishery was closed. Bycatch will continue to be an issue in the drift gillnet and longline fisheries until effective measures are developed which reduce the bycatch to close to zero (Crooke 2001). Although makos are not targeted in these fisheries, they are kept as the third most valuable species. The Short?n Mako shark was taken by the high seas shark and sword?sh drift longline ?shery, which developed between 1991 and 1994 (Taylor and Holts 2001) outside the US 200-nm Exclusive Economic Zone prior to its closure in spring 2004. A small portion of the catch was landed in California with annual landings ranging from 9,523 to 128,116 pounds between 1991 and 1999.
The present status of the short?n mako shark in state and federal waters off California is not known but is of some concern (Taylor and Holts 2001). This is mainly because adult mako sharks do not frequent California?s coastal waters. A possible threat to the mako population off California and in the eastern Paci?c would be the potential for over-development of ?sheries within the coastal nursery. Therefore, continued efforts to monitor the Short?n Mako shark juveniles are needed.
Makos have long been prized game fish along the east coast of the U.S. (Taylor and Holts 2001) (see Threats section). In the mid-to late-1980s, estimates of the number of California angler trips for sharks grew ten-fold from 41,000 to 410,000 annually: the principal target being Shortfin Mako. After the increase during the 1980s, the sport fishery has stabilized at a relatively high level. Total annual landings (sport and commercial) peaked in 1987 at 464,308 pounds and again in 1994 at 394,792 pounds. In both cases, landings declined rapidly in the two years following the peaks. Currently, commercial passenger fishing vessels run fishing trips on a regular basis from nearly all ports in southern California.
In Chile, the only target fishery for shortfin mako is a spring-summer longline fishery off the northern coast (Acuña et al. 2002). In Ecuador, there is evidence that catches of Shortfin Makos have declined from a high of 2,000 t in 1994 to lows approaching 100 t in 2000 and 2001 (Herrera et al. in press).
Off California, early juvenile shortfin makos were targeted by a short-lived experimental drift longline fishery and are a welcome bycatch in the driftnet fishery for swordfish (Cailliet et al. 1993, Compagno 2001). Up to 475 t of Shortfin Makos were taken jointly by these fisheries in 1987, and although CPUE did not show a declining trend there, concerns over the heavy exploitation of immature fish prompted the closure of the experimental longline fishery in 1992 (O?Brien and Sunada 1994, Compagno 2001). Total bycatch of shortfin makos in the former high-seas driftnet fisheries in the North Pacific in the early 1990s was estimated at about 360 t/y (Bonfil 1994, Compagno 2001). This species is apparently very common in the tuna fisheries of Indonesia: unconfirmed reports indicate that landings of shortfin makos from Indonesian waters attained 5 200 t in 1995 and that the estimated potential is about 16 000 t/y (Priyono 1998, Compagno 2001).
This species is taken by tuna and shark longline fisheries in Indonesia (White et al. 2006) and throughout many areas of its range in the Indo-West Pacific. Pelagic fisheries have operated in the Indian Ocean for more than 50 years; Japanese long-liners in the eastern Indian Ocean since 1952 and in the western region since 1956. Russian, Taiwanese and South Korean vessels have fished there since 1954-1966 (Gubanov and Paramonov 1993). The Spanish swordfish longline fishery, which also targets sharks, is also active across the Indian Ocean (ICCAT 2006). Sharks are targeted in several areas, including off India where they are captured on using hook and line and in large mesh gillnets, which are among the worlds largest (Anderson and Simpfendorfer 2005). Finning and discarding of carcasses has also been reported, especially in offshore and high seas fisheries (Anderson and Simpfendorfer 2005). A recent review of fisheries in the Indian Ocean (Young et al. 2006) reported that sharks in this region are considered fully to over-exploited. Its distribution overlaps many intensive pelagic fisheries in this area. Although species-specific catch data are not currently available from this region, given the declines observed where it is heavily fished elsewhere, declines in this area are inferred based on continuing high levels of exploitation.
A vast improvement in the collection of data is required and effective conservation of this species will require international agreements. Fishing pressure must be considerably decreased through reduction in effort, catch limits, measures to enhance chances of survival after capture, when released and possibly through the implementation of large-scale oceanic non-fishing areas. Closed areas can only be effective if overall fishing effort is reduced, rather than merely displacing effort outside of the closed area (Baum et al. 2003).
The Shortfin Mako is listed as a highly migratory species under the 1995 UN Agreement on the Conservation and Management of Straddling Fish Stocks and Highly Migratory Fish Stocks (UNFSA). The Agreement specifically requires coastal and fishing States to cooperate and adopt measures to ensure the conservation of listed species. To date, there has been little progress (see http://www.unclos.com for further details). Also of relevance is the FAO International Plan of Action for the Conservation and Management of Sharks (IPOA-Sharks) which recommends that Regional Fisheries Organisations (RFO?s) carry out regular shark population assessments and that member States cooperate on joint and regional shark management plans. This is of particular importance for species such as shortfin mako whose stocks are exploited by many State on the high seas. Steps are being taken by some RFOs, such as ICCAT, to collect species-specific data on pelagic sharks. To date two RFOs, ICCAT and IATTC, have adopted finning bans, as have several range states (e.g., Canada, USA, EU, Australia, Brazil etc.). More are likely to follow suit.
A recent shark stock assessment (ICCAT 2005) reported that the overall volume of catch reported to ICCAT does not represent the total removals of sharks and that the data are also very limited with respect to the size-, age- and sex- composition of the catch. It is noted that improvements in the ICCAT shark database can only be achieved if the Contracting Parties increase infrastructure investment into monitoring the overall catch composition and disposition of the catch of sharks and by-catch species. The workshop recommended larger monitoring and research investments directed at sharks in particular and by-catch species. The group also identified a number of research activities that could provide for improved advice on the status of these species. This situation applies to all RFOs and is included here as a standard that needs to be applied internationally.
In 2004 ICCAT requested that management recommendations for this species be developed in 2005 for consideration by the Commission (ICCAT 2004), so far without effect. In the fall of 2008, ICCAT and the ICES Working Group on Elasmobranch Fishes (WGEF) plan to assess shortfin mako jointly. In 2007, at the data preparatory meeting of ICCAT?s Shark Sub-committee, it was emphasized that the contribution of CPUE and historical catch data by the member countries would be very important for the stock assessment of this species to be made at the 2008 meeting.
Northwest Atlantic and western central Atlantic
Canada and the USA have shark management plans (NMFS 1993; Joyce 1999). In the US, this species is included in the Highly Migratory Species Fishery Management Plan (FMP). The 1995 Fisheries Management Plan for pelagic sharks in Atlantic Canada established precautionary catch levels of 100 t for Shortfin Makos in the longline pelagic shark fishery. The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) recently assessed Shortfin Mako in Canada as ?threatened?. It has undergone a Recovery Potential Assessment and it is being determined whether the species will be placed on Schedule 1 of the Species at Risk Act. License limitation, a ban on finning, restrictions on gear, area and seasons, by-catch limits and restrictions to recreational fishers permitting hook and release only were also implemented (Hurley 1998). Since 1993, shark fisheries in Atlantic and Gulf of Mexico waters in the US have been managed under the Fishery Management Plan for Sharks of the Atlantic Ocean. The plan set commercial quotas for 10 species of pelagic sharks at 580 t dressed weight annually, with recreational bag limits also applied.
Within the north Atlantic and Mediterranean this species has been identified as a high priority for management. Anonymous (2003) suggested that a collaborative stock assessment should be carried out in the future.
The draft action plan for the conservation of cartilaginous fishes in the Mediterranean Sea (Anonymous 2002) highlights that the Shortfin Mako, along with other large pelagic sharks (whether as target or bycatch), urgently require measures to ensure their sustainable management in the Mediterranean.
On the west coast of the US, declines in the coastal driftnet fishery taking thresher and shortfin makos led to management actions in 1985. Management now comprises of limited entry, mandatory logbooks, and specific time-area closures. An experimental longline fishery targeting Shortfin Makos was terminated (Hanan et al. 1993, Holts et al. 1998). Bag limits for recreational take of makos in California were introduced in 1991. The draft Highly Migratory Species Fishery Management Plan (PFMC 2003) indicates that the shortfin mako population is not overfished and they have set a harvest guideline of 150 t off California, Oregon and Washington. US west coast based longline fishing for swordfish is currently prohibited and expected to reopen in the fall of 2005 under new restrictions. The Hawaii based swordfish longline fishery recently reopened with restrictions aimed at preventing turtle mortalities. New Zealand included shortfin mako shark in its Quota Management System in October 2004.
In Chile, there are gear regulations for the shortfin mako artisanal fishery and since 2002 fishing areas and register of boats in the National Marine Service is required, the access to the fishery is also regulated (E. Acuña pers. comm.).
|Citation:||Cailliet, G.M., Cavanagh, R.D., Kulka, D.W., Stevens, J.D., Soldo, A., Clo, S., Macias, D., Baum, J., Kohin, S., Duarte, A., Holtzhausen, J.A., Acuña, E., Amorim, A. & Domingo, A. 2009. Isurus oxyrinchus. In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.2. <www.iucnredlist.org>. Downloaded on 23 April 2014.|