|Scientific Name:||Isurus oxyrinchus Rafinesque, 1810|
|Taxonomic Source(s):||Eschmeyer, W.N., Fricke, R. and Van der Laan, R. (eds). 2017. Catalog of Fishes: genera, species, references. Updated 30 March 2017. Available at: http://researcharchive.calacademy.org/research/ichthyology/catalog/fishcatmain.asp. (Accessed: 06 April 2017).|
|Red List Category & Criteria:||Critically Endangered A2bd (Regional assessment) ver 3.1|
|Assessor(s):||Walls, R.H.L. & Soldo, A.|
|Reviewer(s):||Dulvy, N.K. & Allen, D.J.|
|Contributor(s):||Fordham, S., Cailliet, G.M., Cavanagh, R.D., Kulka, D.W., Stevens, J., Clò, S., Macias, D., Baum, J.K., Kohin, S., Duarte, A., Holtzhausen, J., Acuna, E., Amorim, A.F. & Domingo, A.|
|Facilitator/Compiler(s):||Walls, R.H.L. & Dulvy, N.K.|
Mediterranean regional assessment: Critically Endangered (CR)
The Shortfin Mako (Isurus oxyrinchus) is an offshore littoral and epipelagic species, found in tropical and warm-temperate seas from the surface down to at least 500 m. It is an important target species, a bycatch in tuna (Thunnus spp.) and billfish (family Xiphiidae and Istiophoridae) longline and driftnet fisheries (particularly in the high seas), and 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 lack of appropriate data precludes the confirmation of whether Mediterranean Shortfin Mako constitute a distinct subpopulation. Data suggest a nursery area exists in the western Mediterranean basin where bycatch of this species from the tuna (family Scombridae) and Swordfish (Xiphias gladius) fishery consists almost exclusively of juveniles. It is possible that this nursery area corresponds to the Eastern Central Atlantic subpopulation, which is affected by the Swordfish longline fishery off the western coast of Africa and the Iberian Peninsula. In other areas of the Mediterranean Sea, the Shortfin Mako is caught sporadically. Reports from the Ligurian Sea show a significant decline in abundance since the 1970s. In the Adriatic Sea, the species was considered common at the end of 19th/beginning of the 20th centuries, but since 1972 there have been no records reported despite a large increase in fishing pressure and introduction of new fishing gear to the area. Given the fact that nothing has changed in terms of management or fishing effort in the Mediterranean Sea since the previous assessment, the status will be carried over. The Shortfin Mako is therefore listed as Critically Endangered in the Mediterranean Sea based on: i) steep localised declines and possible local extinctions in several areas of the region; ii) inadequate management resulting in continuing (if not increasing) fishing pressure throughout the region; iii) the high value of the Shortfin Mako's meat and fins; iv) the sensitive life history characteristics of the species; and v) ongoing captures of juveniles in a probable nursery area.
The Shortfin Mako occurs throughout the Mediterranean Sea; the highest abundance has been reported in the west, and it has rarely been reported from the east (Aegean Sea and Sea of Marmara). Individuals several months old were reported from the western Ligurian Sea (Orsi Relini and Garibaldi 2002) and other regions including Campania, Sicily, and Sardinia (MEDLEM Database). However, the species may be very close to local extinction from the Mediterranean Sea, based on the last reported sighting being from Malta in 2005 (Soldo et al. 2014). It has never been reported from the Black Sea. Despite very low numbers remaining in the region, recent sightings data from the eastern Mediterranean Sea suggest a possible spawning and nursery area in the Aegean Sea (Kabasakal and Kabasakal 2013, Soldo et al. 2014). The depth range is zero to 500 m.
Native:Albania; Algeria; Bosnia and Herzegovina; Croatia; Cyprus; Egypt (Egypt (African part), Sinai); France (Corsica, France (mainland)); Gibraltar; Greece (East Aegean Is., Greece (mainland), Kriti); Israel; Italy (Italy (mainland), Sardegna, Sicilia); Lebanon; Libya; Malta; Montenegro; Morocco; Palestinian Territory, Occupied; Spain (Baleares, Spain (mainland), Spanish North African Territories); Syrian Arab Republic; Tunisia; Turkey (Turkey-in-Asia, Turkey-in-Europe)
|FAO Marine Fishing Areas:|
Mediterranean and Black Sea
The relationship between Shortfin Makos in the Atlantic and Mediterranean Sea is still unclear, therefore the Mediterranean Sea is assessed as a separate subpopulation. Major declines in abundance have occurred, notably in the eastern Mediterranean Sea where the species is now rarely seen (ICES 2012).
Towards the end of the 19th century, the Shortfin Mako was considered common throughout the Mediterranean Sea. “Tonnarella” (tuna-trap) catches in the Ligurian Sea from 1950 to the 1970s showed a rapid decline and eventual disappearance of the species (Boero and Carli 1979). Landings data from the Maltese fishery department from Maltese waters for 1979–2001 showed a decline, with corresponding stable fishing effort, indicating population decline in the area. Since 1998, there have been few records from the central and eastern Mediterranean Sea.
In the eastern Adriatic Sea, the Shortfin Mako was considered common a century ago (Katuri 1893, Kosi 1903), whereas publications from the 1990s considered it to be rare (Jardas 1996). Soldo and Jardas (2002) reported an absence of records of the species in the eastern Adriatic Sea since 1972.
Between 1998 and 2000, this shark was caught more often in the Swordfish fishery in the Mediterranean Sea than any other fishery, with a mean catch per unit effort (CPUE) of 0.07 fish per 1,000 hooks in the “American type” longline and 0.05 fish per 1,000 hooks in the standard longline. It was more abundant in the Alboran Sea and the Levantine basin than other areas of the Mediterranean Sea surveyed by Megalofonou et al. (2005). The Azorean fleet mako landings decreased by almost 50% in numbers from 1987–94 (Castro et al. 1999). This species may have been one of the most overfished pelagic sharks in the Mediterranean Sea (Megalofonou et al. 2005). More recently, across the Mediterranean Sea, total reported landings of the Shortfin Mako for 2011 were just two tonnes (ICES 2012). Since 1997, the Mediterranean Sea catches have always been low (less than nine tonnes), with peak reported catches of 17 and 10 tonnes in 2005 and 2006, respectively.
Ferretti et al. (2008) grouped the Shortfin Mako with the Porbeagle (Lamna nasus) for an analysis of elasmobranch population declines in the Mediterranean Sea, finding the largest declines in the Camogli tuna trap of >99.99% over 56 years, in both abundance and biomass. Similar rates of decline were observed in the northern Ionian Sea, where a large drop in mackerel sharks (family Lamnidae) caught by pelagic longlines was observed in the early 1980s. It should be noted that catch rates were very low even at the beginning of the data series, with an average of 0.2 sharks per 1,000 hooks. The meta-analytical estimate of the rate of decline was >99.99% for biomass (IRD: –0.15; CI 95%: –0.21, –0.10; time range: 106 years) and abundance (IRD: –0.12; CI 95%: –0.22, –0.03; time range: 135 years).
The area around the Strait of Gibraltar could be a nursery area for the north Atlantic subpopulation. However, the status of this nursery is unclear following the severe declines seen throughout the Mediterranean Sea, and indeed the disappearance reported from most Mediterranean regions (Soldo et al. 2014).
Based on the available data, a regional population decline of at least 80% over the past three generation period (75 years) is inferred for the Shortfin Mako in Mediterranean waters. This decline is expected to continue into the future given the lack of effective elasmobranch-focused or species-specific management in the region, coupled with continued or increasing fishing levels.
|Current Population Trend:||Decreasing|
|Habitat and Ecology:|
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 (Compagno 2002). In the Mediterranean Sea, it is presumed that the Strait of Gibraltar is a nursery area (Buencuerpo et al. 1998, Tudela et al. 2005). It is possible that this nursery area is from the north Atlantic subpopulation (Soldo et al. 2014). Stevens (2008) suggested that nursery areas would likely be situated close to the coast in highly productive areas, based on the majority of reports.
The Shortfin Mako is live bearing with yolk sac nutrition and oophagous. What little is known of its reproductive cycle indicates a gestation period of 15–18 months, with a three year reproductive cycle (Mollet et al. 2000). Litter size is four to 25 pups (possibly up to 30, mostly 10–18), which are about 60–70 cm TL at birth (Garrick 1967, Compagno 2002).
Length at 50% maturity in the Northeast Atlantic – presumably akin to that in the Mediterranean Sea – is reportedly 180 cm total length (TL) in males, but no estimate was obtained for females in this region as no mature individuals were caught (Maia et al. 2007). Compagno (2002) found that males mature between 203 and 215 cm TL, reaching a maximum size of 296 cm TL, and females mature between 275 and 293 cm TL, reaching a maximum of almost 400 cm TL. In the Northwest Atlantic, size at maturity is quite similar: ~195 and 265–280 cm TL in males and females, respectively (Pratt and Casey 1983, Stevens 1983, Cliff et al. 1990). From the same region, age at maturity was calculated as 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). The generation length is therefore estimated to be 25 years. Cortés (2002) calculated a finite rate of population increase (lambda) of 1.141 (1.098 to 1.181 95% CI, r = 0.13) and the average reproductive age as 10.1 years (9.2 to 11.1 95% CI). Given the similarity between regional data, the inference can be made that Mediterranean Shortfin Makos have the same life history characteristics.
|Generation Length (years):||25|
|Movement patterns:||Full Migrant|
|Use and Trade:||This is one of the most valuable shark species for its high quality meat, however use of the species sourced from the Mediterranean is not certain. The meat is used fresh, frozen, smoked, and dried-salted for human consumption; the oil is extracted for vitamins; the fins used for shark-fin soup; the hides are processed into leather; and the jaws and teeth are used for ornaments (Compagno 2002).|
The main threat to the Shortfin Mako in the Mediterranean Sea is incidental capture in pelagic fisheries, particularly tuna fisheries using gears such as longlines. Driftnetting is also a major threat to the population, especially since this practise has continued illegally in Mediterranean waters despite being banned in the region (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 one to two miles from the coast where the chance of capturing pelagic sharks is higher. The catch rate for the Shortfin Mako is nearly three times higher in boats actively fishing for sharks (from 0.6–1.9 individuals per fishing operation and 0.06–0.14 catch per km net). Both annual catches and mean weights of the Shortfin Mako have fallen as a result of fishing mortality in the Moroccan driftnet fishery, illustrating the likely effect of this illegal fishery on stocks in the Alboran Sea and adjacent Atlantic (Tudela et al. 2005).
In addition to the primary major threats, this species is a known target of recreational fishers in other areas of the world; this could be relevant to the Mediterranean region as well, but there are no data at present. Moreover, fisheries records are sometimes confused by the widespread use of similar common names for different Mediterranean species; for example, 'Tiger' Shark in Malta may refer to this species, the Sand Tiger Shark (Carcharias taurus), or the Smalltooth Sand Tiger Shark (Odontaspis ferox).
In 2013, the European Union (EU) banned the removal of shark fins on board vessels through Regulation No. 605/2013, in line with advice from the IUCN Shark Specialist Group and other shark fishery experts, in order to enhance enforcement of the 2003 EU ban on shark finning (Regulation No. 1185/2003) and facilitate improved shark fishery data collection.
The Shortfin Mako was listed in 2008 under Appendix II of the Convention on Migratory Species (CMS), based on a proposal from Croatia. The species is thereby covered under the 2010 CMS Memorandum of Understanding (MoU) for Migratory Sharks and an accompanying 2012 Conservation Action Plan for MoU listed sharks, but no species-specific, regional plans or measures have resulted from this listing to date.
Although plans for implementation are not yet evident two years later, Parties to the Barcelona Convention agreed in 2012 that elasmobranch species listed in Annex II of the Protocol concerning Specially Protected Areas and Biological Diversity in the Mediterranean Sea — which includes the Shortfin Mako — cannot be retained on board, transshipped, landed, transferred, stored, sold or displayed, or offered for sale, and must be released unharmed and alive to the extent possible.
Despite its commercial importance, catches of the Shortfin Mako are not limited by European fishery regulations. This is however a protected species in Croatian waters, although enforcement of this protection is as yet unclear. Efforts by the EU and the United States to secure international Shortfin Mako fishing limits through the International Commission for the Conservation of Atlantic Tunas have been unsuccessful to date.
The Shortfin Mako is listed as a highly migratory species under the 1995 United Nations Agreement on the Conservation and Management of Straddling Fish Stocks and Highly Migratory Fish Stocks. The Agreement specifically requires coastal and fishing States to cooperate and adopt measures to ensure the conservation of listed species. Also of relevance is the Food and Agriculture Organization of the United Nation’s International Plan of Action for the Conservation and Management of Sharks (IPOA-Sharks) that recommends that Regional Fisheries Organisations carry out regular shark population assessments and that member States cooperate on joint and regional shark management plans.
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 and when released.
|Citation:||Walls, R.H.L. & Soldo, A. 2016. Isurus oxyrinchus. The IUCN Red List of Threatened Species 2016: e.T39341A16527941.Downloaded on 22 November 2017.|
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