Distribution and Centers of 

 Abundance 



The Pacific dogfish ranges from Baja Cali- 

 fornia, to Alaska in the eastern Pacific, and 

 it has been recorded from off northern China 

 and Japan in the western Pacific. The same 

 fish is found throughout the temperate and 

 subarctic waters of the North Atlantic where 

 it is called the Atlantic spiny dogfish. 



Centers of abundance for dogfish along the 

 Pacific coast of North America have not been 

 studied, although results of the intense com- 

 mercial fishery that was carried on in the 

 midforties did shed some light on the subject. 

 If productive fishing grounds are used as an 

 index, Puget Sound, Strait of Georgia, and 

 waters over the Continental Shelf from northern 

 Washington to Hecate Strait would appear to 

 be the centers of large concentrations. Within 

 Puget Sound, dogfish apparently are common 

 in most of the bays and inlets (figs. 2 and 3). 



Development and Grcwth 



The mating period of the Pacific dogfish 

 is not known with certainty, but Bonham, 

 Sanford, Clegg, and Bucher (1949) have de- 

 scribed the beginnings of embryonic develop- 

 ment in females captured in December. Mating, 

 therefore, probably takes place in fall and 

 early winter. 



The reproductive organs of the female 

 dogfish are relatively complex. The mature 

 dogfish eggs pass from the ovary to the shell 

 gland where they receive the sperm and are 

 fertilized before they receive a protective, 

 transparent membrane or shell. The fer- 

 tilized, shelled eggs then pass to the uterus 

 where they undergo the period of gestation. 

 During gestation, the uterine walls of the 

 shark are thrown into oblique rows of folds 

 or villi through which gaseous materials are 

 exchanged between the mother and the em- 

 bryos (Daniel, 1934). Growth and maturation 

 of the embryos are slow, with gestation last- 

 ing approximately 20 months. Eggs fertilized 

 in December develop into embryos about 8.5 

 mm. (0.33 inches) long by the following March 

 (Bonham, Sanford, Clegg, and Bucher, 1949) 

 and 25 to 50 mm, (1.08-1.97 Inches) by July. 



Just prior to birth, the membrane or shell 

 is shed and the young emerge alive at lengths 

 of 220 to 280 mm. (8.66-11.02 inches). 



Owing to the long gestation period, females 

 can give birth to a set of pups no oftener 

 than every second year. Females from Puget 

 Sound have been observed with from 2 to 20 

 pups, and the average is about 8. Birth of the 

 young takes place in the late fall and early 

 winter of the second year of gestation, gen- 

 erally in November or December. 



Growth after birth continues to be slow. Data 

 from Bonham, Sanford, Clegg, and Bucher, 

 (1949) and Kaganovskaia (1933, 1937) indi- 

 cate that a 61-cm. (24 inches) dogfish is about 

 8 years old. Maturity is probably not reached 

 until after the 10th year of life, for females 

 reach maturity at a minimum observed length 

 of about 92 cm. (36 inches) and males at about 

 72 cm. (28 inches). A 92-cm. (3 feet) male 

 dogfish may be 15 years old. Dogfish live 

 longer than 30 years. 



Feeding 



A great variety of vertebrate and inverte- 

 brate marine organisms have been noted in 

 dogfish stomachs. Bonham, Sanford, Clegg, 

 and Bucher (1949) analyzed stomachs of 1,122 

 dogfish, mostly from Puget Sound \ and found 

 that fish constituted two-thirds of the diet. 

 Food fish accounted for nearly one-half of the 

 volume of identified items. Ratfish (Hydrolagus 

 colliei), herring (Clupea harengus pallasi), and 

 krill (Euphausia sp.) were the items most 

 commonly reported by these authors. 



Chatwin and Forrester (1953) studied the 

 feeding habits of dogfish in the Fraser River 

 estuary, British Columbia, during the springs 

 of 1950 and 1953. They found that dogfish were 

 feeding on eulachonf'rAaZetcAt/jys pacificus) that 

 were entering the river. A positive relation 

 was noted between availability of dogfish to 

 trawlers in the area and the relative abundance 

 of eulachon at the Fraser River mouth. Of the 



'The collection area is not mentioned in the text, 

 but in a telephone conversation with the senior author, 

 Bonham stated that most of the specimens examined 

 were collected in Puget Sound. 



