358 



Abstract-From 1978 to 1988, approx- 

 imately 71,000 spiny dogfish (Squalus 

 acanthias ) were tagged off the west coast 

 of Canada. This program is the most 

 extensive tagging study conducted for 

 a shark species. Twelve years after the 

 last year of tagging, recaptured tagged 

 spiny dogfish are still being reported. 

 As of December 2000. 2940 tagged 

 fish (4.1%) have been recaptured. 

 Spiny dogfish were tagged in three 

 major areas: Strait of Georgia, west 

 coast Vancouver Island, and northern 

 British Columbia waters. Generally, 

 spiny dogfish were recaptured close to 

 their release site; however, extensive 

 migrations (up to 7000 km) did occur 

 Migration rates varied across release 

 areas. Spiny dogfish tagged in the 

 Strait of Georgia underwent the least 

 extensive movement; only 10-14% of 

 the recaptures occurred outside the 

 strait. Spiny dogfish tagged off the 

 west coast of Vancouver Island or in 

 northern British Columbia waters 

 underwent more extensive movement; 

 approximately 49-80% of the tagged 

 spiny dogfish recaptured outside of the 

 release areas. Spiny dogfish from all 

 three release areas were recaptured 

 off the west coast of United States 

 and Alaska. Most impressive are the 

 recaptures of tagged spiny dogfish off 

 the coast of Japan. Over 30 spiny dog- 

 fish were recaptured near Japan, most 

 of which originated off the west coast 

 of Vancouver Island or from northern 

 British Columbia waters. 



Migration patterns of spiny dogfish 



{Squalus acanthias) in the North Pacific Ocean 



Gordon A. McFarlane 

 Jacquelynne R. King 



Pacific Biological Station 



Fisheries and Oceans Canada 



Nanaimo, Bntish Columbia, Canada V9R 5K6 



E-mail address (for G. A. McFarlane, contaa author) McFarlaneSm'pac dfo mpo gc ca 



Manuscript accepted 23 October 2002. 



Manuscript received 31 December 2002 

 at NMFS -Scientific Publication.s Office. 



Fish. Bull. 101:358-367 (2003). 



Interest in sharks, particularly the 

 spiny dogfish (Squalus acanthias), is 

 not new. Off the west coast of British 

 Columbia dorsal spines from spiny 

 dogfish have been found in shell midden 

 sites dating as far back as 4000 years 

 (Ketchen, 1986). Aside from a source of 

 food, the skin of the spiny dogfish was 

 used for polishing, the spines as perfo- 

 ration awls, and the liver oil for various 

 domestic purposes. Dogfish even played 

 a role culturally, for native peoples took 

 the dogfish as a symbol of their families. 

 More recently, commercial fisheries for 

 spiny dogfish were dominant from the 

 late-1800s to the mid-1900s as a source 

 of oil for lubrication, lighting, and vita- 

 min A, and as a source of fishmeal, in 

 addition to or in place of fertilizer. In 

 addition, since the mid-1970s spiny 

 dogfish have been used exclusively as a 

 source of food for human consumption. 



Spiny dogfish biology is equally as 

 fascinating as their cultural history. 

 They are long lived and slow growing, 

 attaining ages in the North Pacific in 

 excess of 80 years, and sizes in excess 

 of 130 cm (McFarlane and Beamish, 

 1987). Females in the North Pacific 

 mature at 35 years (Saunders and Mc- 

 Farlane, 1993). One very unique aspect 

 of dogfish biology is their long gesta- 

 tion period (fertilization to birth) — 22 

 months (Holden, 1977)— which is lon- 

 ger than their closest rival for longest 

 gestation, the Asiatic elephant (Elephas 

 maximus). 



Despite their unique position both 

 economically and culturally, spiny 

 dogfish have been the recipients of 

 considerable disdain, from commercial 

 and sport fishermen alike. The spe- 

 cies has been used as a "poster child" 

 for trash fish and has been accused of 

 preying upon other valuable fish such 



as salmon, herring, and crabs, and of de- 

 stroying fishing gear. Reports of dogfish 

 being released minus their snouts, fins, 

 and tails; of two fish being tied together 

 (tail to tail), and other ghastly stories 

 are common. Despite all this, spiny 

 dogfish are ubiquitous and abundant 

 throughout the North Pacific Ocean. 



Spiny dogfish are distributed from 

 California to Alaska, along the Aleutian 

 chain to the Asian coast, south to Japan. 

 Ketchen (1986) pointed out that knowl- 

 edge of the movements of spiny dogfish 

 and the interrelationships of spiny 

 dogfish from different areas is at best 

 incomplete. In this report, we present 

 the results of the spiny dogfish tagging 

 program conducted off the west coast 

 of Canada between 1978 and 1988. To 

 date, it is the most comprehensive tag- 

 ging program for spiny dogfish or for 

 any shark species. 



Methods 



Tagging occurred in three major areas 

 off the west coast of Canada: Strait of 

 Georgia (SOG) from Johnstone Strait 

 through to, and including, the Juan 

 de Fuca Strait; the west coast of Van- 

 couver Island (WCVI); and northern 

 British Columbia (NBC) from Queen 

 Charlotte Sound through Hecate Strait 

 into Dixon Entrance (Fig. 1). 



One of the impediments to studying 

 spiny dogfish movements has been the 

 availability of a suitable, durable tag. 

 The use of Floy anchor tags was inap- 

 propriate because dogfish placoid scales 

 wore through the plastic. Initially (in 

 1978 and 1979), a Petersen disc tag 

 was used to tag spiny dogfish in the 

 Strait of Georgia. However, based on ob- 

 served severe wounding caused by the 



