Short communication

Updated distribution range of longfin mako Isurus paucus (Lamniformes:Lamnidae) in the North Atlantic

By G. Mucientes1,2, R. Ba~n�on1,3 and N. Queiroz4,5

1IIM-CSIC, Instituto de Investigaciones Marinas, Vigo, Spain; 2CETMAR, Centro Tecnol�ogico del Mar, Vigo, Spain; 3Servizode Planificaci�on, Direcci�on Xeral de Desenvolvemento Pesqueiro, Conseller�ıa do Mar e Medio Rural, Xunta de Galicia, Santiagode Compostela, Spain; 4CIBIO, Centro de Investigac�~ao em Biodiversidade e Recursos Gen�eticos, Vair~ao, Portugal; 5MBA, TheMarine Biological Association of the United Kingdom, Plymouth, UK

Introduction

The mackerel sharks, family Lamnidae, are composed ofthree genera and five species living in tropical and temperate

waters of the Atlantic, Indian, and Pacific oceans (Nelson,2006). The genus Isurus Rafinesque, 1810 is cosmopolitanand represents two species, the shortfin Isurus oxyrinchus

Rafinesque, 1810 and longfin mako sharks Isurus paucusGuitart Manday, 1966 (Compagno, 2001).Widely scattered records suggest that the longfin mako

shark, I. paucus, has a worldwide distribution in tropical and

warm-temperate waters of Atlantic, Indian and Pacificoceans (Compagno, 2001). However, current longfin makorecords are sporadic and the complete distribution remains

unclear (Reardon et al., 2006). This is in part due to themorphological confusion with the more common shortfinmako I. oxyrinchus (Compagno, 2001).

The known Atlantic distribution is limited mainly to shelfareas and it is poorly known in oceanic areas. In the westernAtlantic, it was reported by Garrick (1967) and Dodrill and

Gilmore (1979), in the Gulf of Mexico (Killam and Parsons,1986; Wakida-Kusunoki and Anda-Fuente, 2012), Venezuela

(Cervig�on, 2005) and South Brazil (Amorim et al., 1998). Inthe eastern Atlantic, it is known off Guinea, Ghana and the

Cape Verde Islands (Compagno, 1984) on the northwesternAfrican coast and off the Iberian Peninsula (Moreno andMoron, 1992). Recently, Queiroz et al. (2008) recorded two

sharks in the mid-North Atlantic, northwest of the Azoresislands.Due to its rarity, little is known of the longfin mako life

history. The smallest sexually mature female recorded to date

measured 245 cm in total length (TL), and the smallestmature male 229 cm TL. I. paucus is an aplacental vivipa-rous species with oophagy to nourish embryos; litters of 2–8young have been reported, each measuring 97–120 cm(Gilmore, 1993; Compagno, 2001). Subpopulation structureis unknown, but it is possible that Atlantic and Indo-Pacific

populations may be isolated (Reardon et al., 2006).

Materials and methods

Catch data were collected from two Spanish longline vesselstargeting swordfish Xiphias gladius, I. oxyrinchus and blue

Fig. 1. Details of two Isurus paucusspecimens caught by commerciallongline

U.S. Copyright Clearance Centre Code Statement: 0175-8659/2013/2704–1163$15.00/0

J. Appl. Ichthyol. 29 (2013), 1163–1165© 2013 Blackwell Verlag GmbHISSN 0175–8659

Received: November 14, 2012Accepted: February 11, 2013

doi: 10.1111/jai.12203

Applied IchthyologyJournal of

shark Prionace glauca between 1997 and 2012. Fish weremainly caught between the surface to 70 m depths. Besideshook depth, logbook data also included fishing day, geo-graphic position (latitude and longitude), sea surface temper-

ature (SST), number and fresh weight of each specimen(Table 1). Geographical positions were plotted using ESRI

ArcGis. Morphologically, I. paucus differs mainly in havinga large rounded first dorsal fin, large pectoral fins as long asthe head, moderately long conical snout, lower anterior teethslightly protruding from jaws and in line with the laterals,

and ventral surface of body dusky on underside of head(Compagno, 2001; see also Fig. 1). In contrast, shortfinmakos, I. oxyrinchus, have pectoral fins considerably shorter

than the head, snout usually acutely pointed, and cusps ofupper/lower anterior teeth flexed with reversed tips (Comp-agno, 2001).

Results

A total of 68 specimens ranging between 29 kg and 145 kgwere caught in the mid-Atlantic, 6°–44°N; 19°–54°W(Table 1). Geographical positions are shown in Fig. 2, alsoin relation to the previously confirmed distribution (Compag-

no, 2001). Recorded SST ranged from 14.9 to a maximum of27°C, with an average of 23 � 2.7°C. According to our catchdata from the two longline vessels, the observed ratio

between I. paucus and I. oxyrinchus was 1:364, given that atotal of 24 744 shortfin makos were caught (unpublisheddata).

Discussion

The results obtained here represent a thermal niche expan-sion for I. paucus, since the previously estimated tempera-

tures for one specimen caught in the southeast Pacific Oceanwas 18.5°C (Bustamante et al., 2009), and 22.74°C for themid-North Atlantic records (Queiroz et al., 2008). The pres-ent distribution (Fig. 2) is in agreement with earlier studies

(Queiroz et al., 2008; Bustamante et al., 2009), and confirm-ing the presence of this species in pelagic Atlantic waters.One of the records presented here, an 87 kg specimen caught

on 7 August 2008 at 44.88N/40.55W is, thus far, the north-ernmost reported record. Given the expanded distribution,this species is likely to be more commonly caught as by-catch

by offshore longline vessels in the North Atlantic than waspreviously believed (Moreno and Moron, 1992; Buencuerpoet al., 1998). Moreover, a wider distribution coupled with a

slower growth rate, low reproductive capability and latermaturity than most sharks species, suggest that I. paucus ishighly susceptible to overfishing (Levesque, 2008). In fact,I. paucus were also listed as highly migratory in the conser-

vation of migratory species of wild animals (Bonn Conven-tion) under Appendix II, and classified as vulnerable(Reardon et al., 2006) in the Red List of Threatened and

Endangered Species because it is believed to have undergonesignificant declines in the Atlantic.According to our catch data, the observed ratio between

I. paucus and I. oxyrinchus was 1:364; similarly, Moreno andMoron (1992) also reported a low I. paucus vs. I. oxyrinchuscatch ratio, with only 51 longfin makos landed as opposed to

45679 shortfin makos (a ratio of about 1:896). Althoughthese ratios are likely to be underestimations due to misiden-tifications or non-reporting, this could be an acceptable ini-tial approximation of I. paucus relative abundance in the

North Atlantic. Compagno (2001) and Castro (2011) suggestI. paucus has a greater depth range and is less active thanI. oxyrinchus, which could also explain their scarcity in the

pelagic longline fisheries. Hence, since the overall catchesreported to ICCAT (ICCAT, 2005) are unlikely to representthe total catch of this shark species, any future management

Table 1Catch data of Isurus paucus from fishing vessels ‘Ameal’ and ‘Amel’

Date Latitude Longitude SST NumberWeight(Kg) Vessel

28/09/1999 39.73 �36.85 22.7 1 72.5 Ameal03/07/2000 41.45 �45.42 22.7 1 87 Ameal27/08/2000 40.93 �36.70 24.2 2 116 Ameal13/09/2000 41.77 �38.52 23.3 1 87 Ameal15/09/2001 37.85 �37.67 24.6 1 79.75 Ameal13/12/2001 37.73 �20.92 17.3 2 58 Ameal14/12/2001 37.93 �19.80 17.7 1 72.5 Ameal24/06/2002 37.13 �45.97 21.2 1 145 Ameal16/07/2002 38.72 �43.15 23.8 1 145 Ameal26/09/2003 37.90 �35.28 23.3 1 36.25 Ameal05/10/2003 39.15 �35.98 21.8 1 116 Ameal13/10/2003 39.52 �36.27 21.7 1 145 Ameal15/06/2004 41.70 �38.70 17.8 1 72.5 Ameal24/09/2004 33.35 �33.03 26.1 1 29 Ameal03/10/2004 34.35 �33.88 25 2 94.25 Ameal10/10/2004 33.88 �31.22 24.2 1 145 Ameal16/04/2005 38.18 �49.30 17 1 43.5 Ameal04/09/2005 37.92 �37.47 23.9 1 66.7 Amel07/09/2005 37.85 �39.68 23.2 1 72.5 Amel13/09/2005 37.23 �42.35 24.4 1 101.5 Ameal15/09/2005 38.37 �43.42 22.9 1 78.3 Amel19/09/2005 38.20 �42.58 23.2 1 58 Ameal20/09/2005 38.47 �43.63 23.9 1 110.2 Amel26/09/2005 39.37 �42.15 22.8 1 43.5 Ameal12/10/2005 38.53 �39.53 22.1 1 43.5 Ameal19/12/2005 42.13 �20.98 14.9 1 58 Ameal15/02/2006 8.50 �24.58 25.2 1 78.3 Amel21/02/2006 6.83 �21.40 26.9 1 66.7 Amel22/02/2006 6.70 �21.22 27 1 30.45 Amel24/02/2006 6.22 �20.68 26.5 1 88.45 Amel04/08/2006 37.13 �44.28 26 1 87 Ameal09/08/2006 41.08 �45.10 25.3 1 72.5 Ameal10/08/2006 41.10 �45.07 25.2 1 101.5 Ameal11/08/2006 41.12 �45.05 25.4 1 87 Ameal16/08/2006 41.88 �43.62 24.1 1 79.75 Ameal29/10/2007 33.33 �50.65 24.2 1 72.5 Ameal30/10/2007 33.25 �50.57 23.8 1 43.5 Ameal31/10/2007 33.70 �50.90 23.2 1 87 Ameal04/11/2007 34.13 �50.03 22.6 1 130.5 Ameal05/11/2007 34.12 �50.02 23.2 2 79.75 Ameal08/11/2007 34.02 �50.05 22.9 1 72.5 Ameal10/11/2007 34.18 �47.18 21.4 1 108.75 Ameal24/07/2008 43.38 �45.38 21 1 58 Ameal07/08/2008 44.88 �40.55 23.4 1 87 Ameal05/10/2008 36.23 �39.52 25.3 1 29 Ameal23/10/2008 36.77 �37.82 23.4 1 43.5 Ameal24/10/2008 36.72 �36.83 23.8 1 43.5 Ameal27/10/2008 36.43 �35.97 22.8 1 36.25 Ameal07/11/2008 36.30 �32.05 22.3 1 43.5 Ameal11/11/2008 32.20 �33.77 24.4 1 58 Ameal17/04/2009 38.88 �54.23 18.3 1 60.9 Ameal18/04/2009 39.32 �54.17 17.7 1 60.9 Ameal11/07/2009 43.32 �43.28 19.3 1 84.1 Ameal10/10/2009 43.15 �41.77 21.7 1 – Ameal16/10/2009 35.68 �46.72 21.8 2 145 Ameal19/10/2009 34.12 �49.00 24.2 1 72.5 Ameal21/10/2009 32.82 �48.42 24.6 1 87 Ameal23/10/2009 32.05 �47.75 24.7 1 – Ameal24/10/2009 32.05 �47.88 24.5 1 58 Ameal27/10/2009 32.30 �48.38 24.2 1 145 Ameal20/06/2010 40.05 �48.77 23.2 1 137.75 Ameal02/10/2010 36.08 �38.25 24.7 1 43.5 Ameal29/08/2011 31.75 �36.82 27 1 145 Ameal

1164 G. Mucientes, R. Ba~n�on and N. Queiroz

or conservation attempt is further hampered. The latestICCAT stock assessment (ICCAT, 2012) suggests it is essen-tial to improve I. paucus biological data collection so as toaccurately evaluate its biological productivity. If such spe-

cies-specific fisheries data then becomes openly available,Regional Fisheries Management Organisations (RFMOs)could implement conservation and management measures,

which, given the extended distribution here presented, willlikely require international cooperation and agreements(Reardon et al., 2006; Dulvy et al., 2008). In the absence of

reliable catch statistics, the analysis of logbooks could be animportant source of information on the distribution andabundance of this poorly known species. As a consequence,

given current fisheries data limitations it has been suggestedthat oceanic pelagic sharks may face greater threats thanwhat are currently portrayed in the IUCN Red List catego-ries (Dulvy et al., 2008).

Acknowledgements

We would like to thank the crew of the vessels ‘Amel’ and‘Ameal’ for providing the logbook data. GM was supportedby the Isabel Barreto human resources programme of the

Government of Galicia; NQ was funded by the FCT scholar-ship SFRH/BPD/70070/2010.

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Author’s address: Gonzalo Mucientes, IIM-CSIC, Instituto de Inves-tigaciones Marinas, Eduardo Cabello 6, E-36208Vigo, Spain.E-mail: gonzalo@iim.csic.es

Updated distribution of Isurus paucus in the North Atlantic 1165