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THRESHER SHARK OFF SUFFOLK

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THE OCCURRENCE OF THRESHER SHARK OFF THE SUFFOLK COAST J. R. ELLIS Common thresher shark Alopias vulpinus (Bonnaterre, 1788) (Lamniformes, Alopiidae) is one of three species of thresher shark, and the only species known to occur in the coastal waters of the British Isles (Quéro, 1984). Big eye thresher Alopias superciliosus (Lowe, 1839) occur in offshore areas in the North Atlantic and may be landed occasionally (Thorpe, 1997). It has also been suggested that a fourth species may exist in the Pacific (Eitner, 1995), but specimens to confirm this are lacking. Common threshers have a circumglobal distribution in tropical and temperate waters, and are found in both oceanic and coastal ecosystems (Gubanov, 1972, 1976; Kabasakal, 1998; Compagno, 2001), with the young typically found in shallower waters (Compagno, 2001). It has been suggested that nursery grounds occur in parts of the North-east Atlantic and Mediterranean, including off the Iberian Peninsula (Moreno et al., 1989), although their distribution off North-west Europe is less well known. A. vulpinus predate on a variety of pelagic fishes (e.g. herring, horse mackerel and mackerel) and cephalopods (Pascoe, 1986; Preti et al., 2001). Thresher sharks give birth to live young, with the developing young nourished by a yolk sac and subsequently by feeding on ovulated eggs (oophagy). Fecundity is low, with usually 2–7 pups (Hixon, 1979; Compagno, 2001) born at a length of 114–160 cm (Compagno, 2001). Little is known about the age and growth of thresher sharks (Cailliet et al., 1983), though they are reported to mature at a length of 3·1–3 5 m (males), 3·7–4 m (females), and maximum lengths reported are in the range of 5·6–6·1 m (Quéro, 1984; Compagno, 2001). Thresher sharks have long been known to occur off the coast of Suffolk, with many records resulting from them becoming caught in nets set for herring and mackerel (e.g. Patterson, 1910; Collings, 1933). There are several earlier records of thresher sharks in the North Sea, and these are listed in Table 1. From this it is apparent that both small individuals (<2 m) and larger fish are most often reported in the summer and autumn (June–November). Furthermore, most of the reported captures are from the southern North Sea, with comparatively few captures north of 55ºN (Figure 1). Reasons for this apparent seasonal occurrence of thresher sharks in the southern North Sea is unclear, but could possibly be that the area acts as a nursery ground, or that it is associated with the seasonal abundance of small pelagic fishes, or simply that it reflects seasonal patterns in fishing practices. Three of the more recent captures of A. vulpinus (a 150·5 cm female caught in June 2001, a 146·5 cm male caught in June 2004 and a 132 cm female caught in July 2004) have been examined and morphometric data collected (Table 2). The male specimen was whole and examined fresh. Total weight (WT) was approximately 7·17 kg, of which the liver weighed 652 g (9·09% WT), the alimentary tract weighed 320 g and the gutted weight about 6·2 kg. Stomach contents were composed of unidentifiable digested fish remains. Interestingly, two similarly sized thresher sharks were caught off the Suffolk coast on 17 June 2004, one landed at Aldeburgh (East Anglian Daily

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Table 1: Reports of thresher shark Alopias vulpinus in the North Sea and off Suffolk Date

Size*

Location and capture details

Source

20 Oct 1881 Sept 1897 Nov 7 1898 3 Oct 1905 12 Oct 1906

Lowestoft Lowestoft Lowestoft Sizewell Southwold

Patterson (1910) Patterson (1910) Patterson (1910) Collings (1933) Collings (1933)

Southwold White Bank

Sept 1960

3·66 m (12’) ‘small’ 4·4 m (14’4”) 2·8 m (9¼’) 3·3 m (11’); 131 kg (290 lbs) 1·8 m (6’) 420 cm 170 kg (WG) 372 cm female 114 kg (WG) 403 cm male 185 kg (WG) 406 cm male 100 kg (WG) Male, 450 cm

Oct 1960

Female 406 cm

6 Sept 1962

Male

Collings (1933) Krefft & Kotthaus (1957) Krefft & Kotthaus (1958) Krefft & Kotthaus (1958) Krefft & Kotthaus (1958) Kotthaus (1962) Kotthaus (1962) Krefft (1964)

6 Oct 1962

3·75 m male

8 Oct 1971 21 Nov 1971 5 Oct 1971

450 cm 140 cm 4·2 m

8/9 July 1973

144 cm

15 July 1973 12 June 1973 May 1975

100 cm 350 cm 392 cm male

July 1977

397 cm male 150 kg 435 cm female 180 kg 343 cm male 98 kg

1928 July 1955 22 Sept 1956 24 Sept 1956 24 Sept 1956

July 1977 July 1977

North of Helgoland Silver Pit Dogger Bank 57º00’ N, 01º30’ E (Trawl) 59º03’ N, 03º20’ E (Trawl) 54º05’ N, 02º30’ E (Pelagic pair trawl) 54º05’ N, 02º17’ E (Pelagic pair trawl) 53º55’ N, 02º55’ E 52º40’ N, 04º30’ E 54º10’ N, 03º10’ E (Pair trawl, 35–42 m) 3 miles off Lowestoft (Rod and line) Sizewell Bank 52º40’ N, 04º08’ E 50º43’ N, 01º27’ E (eastern English Channel) 51º25’ N, 01º49’ E

Krefft (1964) de Groot (1973) de Groot (1973) Blacker (1973) Blacker (1975) Blacker (1975) de Groot (1975) Du Buit et al. (1977) Du Buit et al. (1979)

51º25’ N, 01º49’ E

Du Buit et al. (1979)

50º25’ N, 01º08’ E (eastern English Channel)

Du Buit et al. (1979)

Trans. Suffolk Nat. Soc. 40 (2004)


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THRESHER SHARK OFF SUFFOLK

Table 1 continued July 1977

343 cm male 98 kg

July 1982 28 June 1983 August 1984 02 July 1987

5 m (estimate) 150 cm 128 cm, 5·1 kg 95 c m

01 June 1987

7·3 kg (16 lb)

11/12 June 2001 Female, 150·5 cm LT 66 cm LPC, WG=6·365 kg June 2003 9 kg (20 lbs) March 2004 17 June 2004

17 June 2004 29 June 2004 06 July 2004

50º25’ N, 01º08’ E (eastern English Channel) 52º30’ N, 02º00’ E Off Camperdown 1 km off Caister 3–6 miles off Blyth (Salmon drifter) Off Pakefield Beach (Herring drifter) Off Brittania Pier, Great Yarmouth (Herring net)

Du Buit et al. (1979)

Bass nets, Blackwater

A. Talbot (pers. comm.) A. Talbot (pers. comm.)

No data

Caught in ray nets on the Bench Head (River Colne) Male, 146·5 cm 52º17’ N, 01º39’ E LT, 66·4 cm LPC, (Gillnet), landed at 75 cm LF, Southwold WT=7·17 kg, WG=6·20 kg Ca. 146 cm Off Sizewell, landed at Aldeburgh No data Landed at Southwold Male, 132 cm St Osyth Beach LT, 58 cm LPC, (51º27·7’N, 01º01·2’ E) 67 cm LF, Weight = 3·7 kg

Millner (1985) de Groot (1986) Millner (1986) CEFAS CEFAS This study

This study

EADT (19/06/04) N. Curtis (pers. comm.) This study

*Data on length should be used with caution, as most reports do not identify which length measurement was recorded. More recent data provide total length (LT), precaudal length (LPC) and/or fork length (LF). Similarly, weights should be used with caution unless identified as total weight (WT) or gutted weight (WG). Where length or weight measurements have been converted from imperial measurements, the original measurements are given in parentheses.

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Table 2: Morphometrics of two juvenile thresher shark. Dimensions follow Compagno (2001) Specimen Date caught

A

11/12 June 2001 17 June 2004

Sex/Gutted weight Dimension Pre-caudal fin length Total length Fork length Pre-second dorsal fin length Pre-first dorsal fin length Head length Pre-branchial length Pre-spiracular length Pre-orbital length Pre-pectoral fin length Pre-pelvic fin length Snout-vent length Pre-anal fin length Interdorsal space Dorsal-caudal fin space Pectoral fin-pelvic fin space Pelvic fin-anal fin space Anal fin-caudal fin space Pelvid fin-caudal fin space Vent-caudal fin length Pre-narial length Pre-oral length Eye length Eye height Intergill space Mouth length Mouth width Internarial space Inter-orbital space Outer clasper length Inner clasper length Clasper width Spiracle length (mm) First dorsal: Height First dorsal: Base First dorsal: Inner margin

B

F

6·4 kg

M 6·20 kg

cm

% LPC

cm

66 150·5 – – 32 – 16 8·61 4·1 18·7 – – – 18 – 20 6·94 – – – 3·1 5·27 – – – 3·64 7·34 1·83 6·12 – – – 1·4–1·6 8·5 9·04 1·01

100·0 228·0 – – 48·5 – 24·2 13·0 6·2 28·3 – – – 27·3 – 30·3 10·5 – – – 4·7 8·0 – – – 5·5 11·1 2·8 9·3 – – – – 12·9 13·7 1·5

66·4 146·5 75 60 32 19·1 14·8 6·8 3·3 20 45 48·5 61 19·25 7·05 20·8 6·95 3·6 11·5 86 2·6 4·9 1·9 2·4 4·3 3·7 7·0 1·45 6·78 3·0 6·5 0·6 – 8·2 8·7 1·0

Trans. Suffolk Nat. Soc. 40 (2004)

C 06 July 2004 F

% LPC

cm

% LPC

100·0 220·6 113·0 90·4 48·2 28·8 22·3 10·2 5·0 30·1 67·8 73·0 91·9 29·0 10·6 31·3 10·5 5·4 17·3 129·5 3·9 7·4 2·9 3·6 6·5 5·6 10·5 2·2 10·2 4·5 9·8 0·9 – 12·3 13·1 1·5

58 132 67 50·5 28 18 13·5 – 3·2 16·5 39·8 43 52·5 16 6·9 17·1 7·3 4·65 13·4 87·5 3 5 1·9 2·1 4·65 3.05 6·3 1·73 5·6 – – – – 6·8 7·1 1

100 227·6 115·5 87·1 48·3 31·0 23·3 – 5·5 28·4 68·6 74·1 90·5 27·6 11·9 29·5 12·6 8·0 23·1 150·9 5·2 8·6 3·3 3·6 8·0 5·3 10·9 3·0 9·7 – – – – 11·7 12·2 1·7


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THRESHER SHARK OFF SUFFOLK

Table 2 continued Specimen Date caught Sex/Gutted weight Dimension First dorsal: Length First dorsal: Anterior margin First dorsal: Posterior margin Second dorsal: Height Second dorsal: Base Second dorsal: Inner margin Second dorsal: Length Second dorsal: Anterior margin Pectoral fin: base Pectoral fin: inner margin Pectoral fin: anterior margin Pectoral fin: posterior margin Anal fin: base Anal fin: inner margin Anal fin: length Anal fin: height Pelvic fin: base Pelvic fin: inner margin Pelvic fin: length Pelvic fin: anterior margin Pelvic fin: posterior margin Dorsal caudal fin margin Preventral caudal fin margin Upper postventral caudal fin margin Lower postventral caudal fin margin Caudal fin fork length Subterminal caudal fin margin Terminal caudal fin margin Terminal caudal fin lobe

A

B

C

11/12 June 2001 17 June 2004 F

6·4 kg

cm % LPC 10·05 15·2 11 16·7 – – 0·6 0·9 1·07 1·6 1·93 2·9 3 4·5 – – 9·2 13·9 2·55 3·9 – – – – 0·85 1·3 2·35 3·6 3·2 4·8 – – – – – – – – – – – – – – – – – –

M

6·20 kg

cm % LPC 9·7 14·6 11·0 16·6 8·5 12·8 1·0 1·5 1·4 2·1 1·8 2·7 3·2 4·8 1·55 2·3 – – 2·8 4·2 20·5 30·9 16·5 24·8 1·55 2·3 1·8 2·7 3·35 5·0 0·9 1·4 7·5 11·3 2·4 3·6 9·9 14·9 8·9 13·4 8·6 13·0 79·2 119·3 9·8 14·8 69·5 104·7

06 July 2004 F

cm

% LPC

8· 1 14· 0 9· 2 15· 9 7· 3 12· 6 0· 55 0· 9 1 1· 7 1.5 2.6 2.5 4.3 1· 2 2· 1 6· 85 11· 8 2· 3 4· 0 17· 7 30· 5 14 24· 1 1 1· 7 2· 1 3· 6 3· 1 5· 3 0· 55 0· 9 5· 75 9· 9 2· 05 3· 5 7· 8 13· 4 7· 3 12· 6 7· 45 12· 8 74· 5 128· 4 8· 4 14· 5 – –

4·1

6·2

– – – –

– – – –

7·4 1·55 4·9 6·25

11·1 2·3 7·4 9·4

7· 3 1· 55 4· 15 5· 05

12· 6 2· 7 7· 2 8· 7

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78 60.0

59.5

59.0

58.5

58.0

57.5

57.0

56.5

56.0

55.5

55.0

Blyth White Bank

Dogger Bank

54.5

54.0

Silver Pit

53.5

53.0

Caister Great Yarmouth Lowestoft Southwold Aldeburgh

52.5

52.0

51.5

51.0

50.5

50.0 -2

-1

0

1

2

3

4

5

6

7

8

9

Figure 1: Occurrence of thresher sharks in the North Sea (Data sources given in Table 1).

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Times, 19 June 2004), and one landed at Southwold (see Plate 8). The total weight of the 132 cm female caught in July 2004 was 3·7 kg, and this specimen was frozen whole. During the subsequent examination, liver weight was 192·5 g (5.2% WT) and the alimentary tract weighed 144·7 g. Given that there are several reports of juvenile thresher shark, many within the range cited as the size at birth (Compagno, 2001), it is possible that the southern North Sea may sometimes serve as a nursery area for thresher shark, though more data (e.g. the confirmed presence of females with near-term pups or recently-born pups) are required. Acknowledgements Thanks are given to the fishermen and fish merchants who made the three thresher sharks available for study, and Nick Dulvy for comments on the manuscript. References Blacker, R. W. (1973). English observations on rare fish in 1971. Annales Biologiques, Copenhagen 28: 221–222. Blacker, R. W. (1975). English observations on rare fish in 1973. Annales Biologiques, Copenhagen 30: 208–209. Cailliet, G. M., Martin, L. K., Harvey, J. T., Kusher, D. & Welden, B. A. (1983). Preliminary studies on the age and growth of blue, Prionace glauca, common thresher, Alopias vulpinus, and shortfin mako, Isurus oxyrinchus, sharks from California waters. In Proceedings of the International workshop on age determination of oceanic pelagic fishes: Tunas, billfishes and sharks (E. D. Prince & L. M. Pulos, eds.) NOAA Technical Report NMFS 8: 179–188. Collings, D. W. (1933). The fishes of Suffolk. Trans. Suffolk Nat. Soc. 2: 104– 133. Compagno, L. J. V. (2001). Sharks of the world. An annotated and illustrated catalogue of shark species known to date. Volume 2. Bullhead, mackerel and carpet sharks (Heterodontiformes, Lamniformes and Orectolobiformes). FAO Species Catalogue for Fishery Purposed No. 1, Vol. 2, 269 pp. de Groot, S. J. (1973). Dutch observations on rare fish in 1971. Annales Biologiques, Copenhagen 28: 222–223. de Groot, S. J. (1975). Dutch observations on rare fish in 1973. Annales Biologiques, Copenhagen 30: 209–210. de Groot, S. J. (1986). Dutch observations on rare fish in 1983. Annales Biologiques, Copenhagen 40: 188. Du Buit, M. H., Gueguen, J., Lamolet, J. & Quero, J. C. (1977). Observations sur les poissons rares en 1975. Annales Biologiques, Copenhagen 32: 185– 188. Du Buit, M. H., Gueguen, J., Lamolet, J. & Quero, J. C. (1979). Observations françaises sur les poissons rares en 1977. Annales Biologiques, Copenhagen 34: 231–233. Eitner, B. J. (1995). Systematics of the genus Alopias (Lamniformes: Alopiidae) with evidence for the existence of an unrecognized species. Copeia 1995(3): 562–571.

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Gubanov, E. P. (1972). On the biology of the thresher shark (Alopias vulpinus (Bonnaterre)) in the northwest Indian Ocean. Journal of Ichthyology 12(4): 591–600. Gubanov, E. P. (1976). The first recapture of a tagged thresher shark Alopias vulpinus Bonnaterre. Vopr. Ikhtiol. 16(3): 552–553. Hixon, M. A. (1979). Term fetuses from a large common thresher shark, Alopias vulpinus. California Fish and Game 65(3): 191–192. Kabasakal, H. (1998). A note on the occurrence of the thresher shark, Alopias vulpinus from south-western Black Sea. Journal of the Marine Biological Association of the United Kingdom 78(2): 685–686. Kotthaus, A. (1962). Rare fish: Germany. Annales Biologiques, Copenhagen 17: 109. Krefft, G. (1964). Rare fish: Germany. Annales Biologiques, Copenhagen 19: 81–82. Krefft, G. & Kotthaus, A. (1957). Rare fishes: Germany. Annales Biologiques, Copenhagen 12: 104. Krefft, G. & Kotthaus, A. (1958). Rare fishes from near northern seas: Germany. Annales Biologiques, Copenhagen 13: 96 Millner, R. S. (1985). English observations on rare fish in 1982. Annales Biologiques, Copenhagen 39: 186. Millner, R. S. (1986). English observations on rare fish in 1984. Annales Biologiques, Copenhagen 41: 162–163. Moreno, J. A., Parajua, J. I. & Moron, J. (1989). Breeding biology and phenology of Alopias vulpinus (Bonnaterre, 1788) (Squaliformes: Alopiidae) in the north-eastern Atlantic and western Mediterranean. Scientia Marina 53(1): 37–46. Pascoe, P. L. (1986). Fish otoliths from the stomach of a thresher shark, Alopias vulpinus. Journal of the Marine Biological Association of the United Kingdom 66: 315–317. Patterson, A. H. (1910). Rough notes on the Fish and Fisheries of East Suffolk. John Buckle, Great Yarmouth, 55 pp. Preti, A., Smith, S. E. & Ramon, D. A. (2001). Feeding habits of the common thresher shark (Alopias vulpinus) sampled from the California-based drift gill net fishery, 1998–1999. Reports of California Cooperative Oceanic Fisheries Investigations 42: 145–152. Quéro, J.-C. (1984). Alopiidae. In Fishes of the North-eastern Atlantic and the Mediterranean (P. J. P. Whitehead, M. L. Bauchot. J.-C. Hureau, J. Nielsen & E. Tortonese, Eds.), Volume 1. UNESCO, Paris, pp. 91–92. Thorpe, T. (1997). First occurrence and new length record for the bigeye thresher shark in the north-east Atlantic. Journal of Fish Biology 50: 222– 224. Jim Ellis, CEFAS Lowestoft Laboratory, Pakefield Road, Lowestoft, Suffolk, NR33 0HT

Trans. Suffolk Nat. Soc. 40 (2004)


J. R. Ellis Plate 8: Common thresher shark Alopias vulpinus (Bonnaterre, 1788), caught off the Suffolk Coast and landed at Southwold, 17 June 2004 (p. 79).

THE OCCURRENCE OF THRESHER SHARK OFF THE SUFFOLK COAST  

Jim Ellis

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