摘要:

Crustacean food is partially broken down and digested in the caecum of the stomach of the herring. It becomes more finely divided in the pyloric sac and consists of an oily chyme, intermingled with chitin, mucus and bacterial clumps in the pyloric caeca and intestine. The acidic condition of the gastric contents is probably instrumental in the reddening of chitinous food in the tract. Pepsin from the stomach and trypsin from the pyloric caeca increase in digestive power over a temperature range from 2.4 to 37.5 °C. The stomach secretes a protease (pepsin), a weak amylase, and possibly a weak lipase. The pyloric caeca secrete a strong protease (trypsin), a strong amylase, and a lipase rendered active by bile. The intestinal mucosa exhibits lipolytic and amylolytic ferments, while the bile has some amylolytic properties.

ISSN:0706-652X    

DOI:10.1139/f35-001

出版商:NRC Research Press    

年代:1935

数据来源: NRC

摘要:

In 1,557 fish examined, the groups, based upon years in the sea and spawning marks, were:—grilse or 1+, 2 and 2+, 3 and 3+, and 1 S.M. and 2 S.M. groups. The 2 and 2+ form 85.1 per cent of the total (grilse excluded), and S.M. 12.8 per cent, and the 3 and 3+, 2.1 per cent.Of fish with one spawning mark, 68.3 per cent first spawned as grilse, 29.9 per cent after two sea winters, and 1.8 per cent after three sea winters. The S.M. group had 11 per cent return to river in less than a year after first spawning, the remainder in little better than a year. Most of the fish with two spawning marks had the same length of absence on both occasions.Only four smolt ages were found:—3 (78.1 per cent), 2 (15.1 per cent), 4 (6.6 per cent) and 5 (0.2 per cent).

ISSN:0706-652X    

DOI:10.1139/f35-002

出版商:NRC Research Press    

年代:1935

数据来源: NRC

摘要:

Large scale mixing in the region of the tidal reversing falls of the Saint John river water with salt bay of Fundy water gives light mixed water traceable during spring freshets as far as Grand Manan. This water when moving out may cause renewal of the bay of Fundy waters, at a rate of over 4,000,000 cu. ft./sec. (over 97,000,000 litres/sec).

ISSN:0706-652X    

DOI:10.1139/f35-003

出版商:NRC Research Press    

年代:1935

数据来源: NRC

摘要:

Cod, haddock, salmon, herring, skate and lobster, were investigated, the first two alone proving to be closely related chemically. In the first four the total non-protein nitrogen is of the same order; but in skate it istimes as great, due to urea, ammonia and other volatile bases, and in lobstertimes as great, due to the monoamino acid and histidine-arginine fractions. Cod is very rich in the lysine fraction and poor in the histidine-arginine fraction, the reverse of the condition in ox. In herring this difference is also present but is not so great. In lobster the lysine fraction is slightly less than in cod but the nitrogen of the histidine-arginine fraction is extremely high.

ISSN:0706-652X    

DOI:10.1139/f35-004

出版商:NRC Research Press    

年代:1935

数据来源: NRC

摘要:

Approximately 20,000 measurements were made of crabs and cast exoskeletons, chiefly from Boundary bay, southern British Columbia.From size frequencies of crabs under 3 cm. seven modes have been identified as representing the early post-larval instars. Increase in size of animals in the laboratory or in live wells is significantly less than in nature, and leads to erroneous results when applied to growth.The increase per moult decreases from about 40 per cent in the early post-larval stages to about 15 per cent in males of 13.5 cm. and 10 per cent in females of 13.0 cm. Above 10 cm. the males increase more per moult. The intervals between moults become progressively longer with increasing size, and tagging experiments indicate that large crabs moult yearly. Probably to reach the maximum size, seventeen and sixteen post-larval instars are required for males and females respectively.Sexual maturity in female crabs is probably attained during the fourth or fifth year but may occur in the third or the sixth year. The legal size in British Columbia (6½ inches, or 16.5 cm.) is probably attained during the seventh or eighth year. The average duration of life is probably about eight years and the maximum age not more than ten years.

ISSN:0706-652X    

DOI:10.1139/f35-005

出版商:NRC Research Press    

年代:1935

数据来源: NRC

摘要:

The claws of males and the width and depth of abdomen of females increase at a higher rate than body length with approaching sexual maturity. Consequently for lobsters over 20 cm. in length males possess claws relatively larger and females an abdomen relatively wider and deeper in an area such as that near Pointe du Chêne where sexual maturity occurs at about 20 cm. than in that near Grand Manan where lobsters only become sexually mature at about 34 cm.

ISSN:0706-652X    

DOI:10.1139/f35-006

出版商:NRC Research Press    

年代:1935

数据来源: NRC