Figure I. — Location of plankton and oceanographic sampling stations 

 occupied monthly in southeastern Alaska, April-November 1972. 



sisting of stations 1-12, extended southerly from Dyea in 

 northern Lynn Canal to Auke Bay, located about 19.3 km 

 northwest of Juneau. A southern cruise, stations 13-21, 

 ranged from Gambler Bay on Admiralty Island to the 

 junction of Frederick Sound and Chatham Strait near 

 Red Bluff Bay. The only months when all stations could 

 be sampled were May, June, and July. Beginning in 

 August, stormy weather reduced sampling to 18 stations 

 in August, 15 stations in September, 16 stations in Oc- 

 tober, and only 7 stations in November. 



Before sampling for zooplankton, we completed a stan- 

 dard oceanographic station including surface observations 

 (wind, wave, cloud cover, temperatures, barometric 

 pressure, and water transparency), subsurface obser- 

 vations (temperature, salinity, oxygen, phosphates, 

 nitrates, silicates, and chlorophyll a), and a surface 

 phytoplankton collection. The physical and chemical ob- 

 servations are on file at the National Oceanographic 

 Data Center, National Oceanic and Atmospheric Ad- 

 ministration, U.S. Department of Commerce, Rockville, 

 MD 20852, and data on the phytoplankton composition 

 were reported by Williamson.' 



Zooplankton samples were collected with a bongo net 

 array consisting of a 20-cm (mouth diameter) frame 

 equipped with 0.253- and 0.333-mm mesh nets placed 1.0 

 m above a 61-cm frame equipped with 0.333- and 0.505- 

 mm mesh nets. A 1.2-m Braincon type 275 v-fin depres- 

 sor was suspended 1 m below the larger bongo frame. 

 Sampling depths were recorded with a Bendix Model Tl 

 bathykymograph of 300-m depth range. General 

 Oceanics Model 2030 digital flowmeters were used to es- 

 timate water filtered. 



Sampling technique was a single oblique tow in depths 

 over 150 m, and multiple oblique tows in shallow depths 

 (100 m or less). Target sampling depths ranged from 50 

 m in shallow bays and channel margins to 3(X) m at the 

 deepest channel stations (Table 1). Towing was at a con- 

 stant surface speed of 2 kn (1.029 m/s). Tow cable was 

 served out at 60 m/min and retrieved at 20 m/min, while 

 rates were monitored by stopwatch and cable amounts 

 by a dial-reading meter wheel. When necessary, winch 

 speed changes were made verbally to the winch operator. 

 Towing times ranged from 12 to 47 min, depending upon 

 target depth and maneuvering room within confined 

 bays. Towing distances ranged from 0.7 km (0.4 n.mi.) to 

 2.9 km (1.6 n.mi.). When multiple shallow oblique tows 

 were made, the nets were raised until visible, checked for 

 debris or plugging, then lowered. Upon tow completion, 

 all samples were preserved in 3-5^c unbuffered seawater 

 formaldehyde. 



For processing, the samples were taken to the 

 laboratory where the formaldehyde was buffered with a 

 saturated borax solution. We processed only the catches 

 by the 61-cm, 0.333-mm mesh net. Each sample was 

 sorted in its entirety under a dissecting microscope at 

 magnifications of 7-lOX. All fish eggs and fish larvae 

 were removed and counted. Only the fish larvae were 

 identified. Notes were kept on the abundance rank of 

 general plankton categories. Total settling volumes of 

 plankton were estimated to the nearest 25 ml in a 

 graduated 0.95-liter (1 qt) widemouth bottle. 



The data were converted to standardized tows as num- 

 bers under 10 m^ of water surface (computed as number 

 per 10 m' per meter of tow depth (Ahlstrom 1948) ) for 

 larval fish and eggs and to milliliters per 1,000 m' of 

 water filtered for the plankton settling volumes. 



RESULTS 



One hundred twenty-six plankton tows were com- 

 pleted at the regular stations of which 119 were sorted for 

 fish eggs and fish larvae (Table 2). Three samples, sta- 

 tion 13 in May and stations 13 and 14 in June, were 

 processed for plankton volumes but not for ichthyo- 

 plankton because of exceptionally high quantities of 

 phytoplankton. Samples from four tows could not be 

 processed because they contained large amounts of mud 



'Williamson, R. 1974. Phytoplankton species and their geographical 

 distribution in southeast Alaska. Northwest and Alaska Fisheries Cen- 



ter Auke Bay Laboratory. National Marine Fisheries Service, NOAA, 

 Auke Bay. AK 99821. Unpubl. manuscr. 



