August 1966 



COMMERCIAL FISHERIES REVIEW 



39 



namics and secular changes in water masses. 

 Three cruises by other Bureau laboratories, 

 studying herring, lobsters, and acoustical 

 problems occupied 44 days. Other cruises 

 included research on the benthos, midwater 

 distribution of juvenile groundfish, serology 

 of groundfishes, and sea scallop populations. 



'r 'r ^ ^ ^ 



DISTRIBUTION OF 



ZOO PLANKTON STUDIED: 



M/V " Rorqual '' Cruise 4-66 (May 17-26, 

 1966): To determine the inshore -offshore 

 and vertical distribution of zooplankton with 

 regard to hydrographic conditions in an area 

 extending from Cape Ann to Machias Bay, 

 Me., was the objective of this cruise by the 

 research vessel Rorqual , operated by Inter- 

 iqr's Bureau of Commercial Fisheries. 



BIOLOGICAL OBSERVATIONS: Plankton 

 tows lasting 15 minutes each using Clarke- 

 Bumpus closing samplers in a vertical series 

 0, 10, 30, and 60 meters (0, 32.8, 98.4 and 

 196.8 feet), were made along 6 transects from 

 inshore to the 100 -meter (328 feet) isobath. 

 Oblique tows from to 20 meters (0 to 65.6 

 feet) and lasting 30 minutes each were taken 

 using a Gulf III sampler at 8 coastal continu- 

 ity stations and at 4 additional locations. Ex- 

 ploratory Clarke-Bumpus tows were made in 

 Pleasant Bay and the Machias, Sheepscot, and 

 Piscataqua Rivers. 



HYDROGRAPHIC OPERATIONS: At each 

 station: (1) a Nansen bottle cast was made to 

 determine salinity at 0, 10, 20, and 30 meters 

 and the bottom; (2) a bathythermograph (BT) 

 cast was made to determine vertical temper- 

 ature distribution; (3) water transparency was 

 measured with a Secchi disc; and (4) meteo- 

 rological observations were recorded. Five 

 sea -bed drifters and 5 surface drift bottles 

 were released at each station. 



PRELIMINARY FINDINGS: The average 

 concentration of zooplankton along the coast 

 was not significantly different (P>.05) from 

 the average station value obtained in spring 

 1965. However, the center of zooplankton 

 abundance shifted from the western Gulf coast 

 in 1965 to the central area this year. The 

 average volume in the western area was 4 

 times lower than in 1965. As in previous 

 years, the lowest areal volumes occurred in 

 the eastern sector. 



Copepods were the dominant zooplankters 

 in the western and central Gulf coast (70 per- 



cent of the zooplankton). Larval barnacles 

 were numerous in the eastern area (82 per- 

 cent of the zooplankton). Calanus finmarchi- 

 cus was the dominant copepod species in all 

 areas. 



Note: See Commercial Fisheries Review , April 1966 p. 29. 



North Pacific Fisheries Explorations 

 and Gear Development 



HAKE POPULATION SURVEY CONTINUED: 

 M/V " John N. Cobb ," Cruise 78 (May 13- 

 June 10, 1966): To determine the distribution 

 of schools of hake ( Merluccius productus ) in 

 Puget Sound and the coastal waters of Washing- 

 ton was the primary objective of this 4 -week 

 midwater trawling cruise by the exploratory 

 fishing vessel John N. Cobb , operated by the 

 Bureau of Commercial Fisheries, U.S. Depart- 

 ment of the Interior. Secondary objectives 

 were to (1) obtain biological data on Pacific 

 hake and (2) obtain additional data on the a- 

 vailability of hake to the "Cobb" pelagic trawl. 



Bureau of Commercial Fisheries exploratory fishing vessel M/V 

 John N. Cobb . 



Echo-sounding transects were made to lo- 

 cate concentrations of hake and their avail- 

 ability was measured with the "Cobb" pelagic 

 trawl. These transects were made through- 

 out Puget Sound and in the coastal waters of 

 Washington between 25 and 100 fathoms. 



PUGET SOUND: Hake concentrations were 

 located in Saratoga Passage, Port Susan to 

 Port Gardner, Possession Sound, and Hood 

 Canal. In Saratoga Passage the fish signs 

 were sporadic and light and were mainlyfound 

 along the western side of the Passage close 

 to shore. Hake signs in Port Susan were more 

 concentrated than those in Saratoga Passage 

 and were found as far north as Kayak Point 



