ABSTRACT 



A detailed account and evaluation are presented 

 for certain methods used by the STOR (Scripps 

 Tuna Oceanography Research) Program. This de- 

 scription should assist readers and users of the 

 STOR data and be of general interest to workers 

 in the field. 



An Eppley 10-junction 180° pyranometer was 

 used in conjunction with a Speedomax recorder for 

 the measurement of incident solar radiation. Daily 

 incident radiation was obtained by integration of 

 the daily record with a polar planiraeter. Errors 

 due to integration and failure of the gimbals to 

 stabilize the pyranometer completely are estimated 

 to be ± 1 percent and zt 5 percent, respectively. 

 A comparison between observed daily radiation and 

 computed radiation from four standard climatologi- 

 cal equations revealed the inaccuracy of using in- 

 direct methods for daily totals. 



The deck and submarine irradiance meters were 

 equipped with cosine collectors; their construction, 

 calibration, and operation are described. A blue- 

 green Wratten filter (No. 45) was routinely used 

 with both detectors. The relative spectral sensitiv- 

 ity in air and Jerlov ocean water type I was cal- 

 culated. In air, the maximum transmittance was 

 at 490 mil and the half-band width was roughly 

 63 m/i. At 100-m depth in type I water, this value 

 shifted to 475 m/i with a 50 m/i band width. By 

 assuming the universal validity of the Jerlov sea- 

 water transmission curves, it was possible to obtain 

 estimates of total visible downwelling irradiance at 

 depth from a single attenuation coefficient measure- 

 ment. Under ideal conditions and with no depth 

 measurement error, a coeflncient of variation of 

 lb 10.5 percent was obtained for the attenuation co- 

 efficient. This error increased appreciably when 

 vessel motion and errors of depth measurement oc- 

 curred. 



Chlorophyll a measurements were obtained by 

 spectrophotometric method with acetone extracts 

 of membrane-filtered water samples. Corrections 

 for blank values at 750 m/j were applied, and con- 

 centrations computed with the equations of Richards 

 with Thompson. The coefficient of variation for 

 surface samples varied between 14 and 27 percent 

 and increased with depth. 



Primary production was measured with C"; the 

 details of the methodology and standardization are 

 given. Because a number of different incubation 

 techniques were used (i.e., in situ, deck incubator, 

 trailing bottle, and laboratory incubator) , an at- 

 tempt was made to compare these procedures with 

 the in situ method. All of the methods yielded 

 results which were correlated with those obtained 

 by the in situ method. Thus unbiased estimates of in 

 situ production may be obtained from the different 

 incubation techniques. 



565. Passage conditions and counts of fish at 

 the Snake Island fishway, Little Falls Dam, 



Potomac River, Md., 1960-63, by Paul R. 



Nichols. February 1968, iii + 14 pp., 7 figs., 



5 tables. 



ABSTRACT 

 Resident fish such as sucker, carp, channel cat- 

 fish, bluegill, and black crappie travelled through 

 the fishway, but apparently no anadromous fish 

 ascended the river far enough to reach the fishway. 

 It is possible that: (1) the runs of anadromous 

 fish are now at such a low level that the spawning 

 area above Little Falls is not needed as in former 

 years; (2) the stocks with the instinct to move 

 above Little Falls which were blocked from their 

 natural spawning ground when the Little Falls Dam 

 was rebuilt in 1949 have since disappeared; and 

 (3) the rapids between Chain Bridge and the fish- 

 way may deter the upstream progress of migrating 

 fish. 



Success in reestablishing runs of anadromous fish 

 above Little Falls may require the planting of 

 fertilized eggs and adult fish in the upper river 

 and the construction of fish-passage facilities at 

 the rapids above Chain Bridge. Successful hatch- 

 ing of shad eggs and the collection of young shad 

 above Little Falls indicate that the river is suitable 

 for the restoration of this species. 



566. Horizontal and vertical distribution of 

 juvenile salmonids in upper Mayfield Reser- 

 voir, Washington, by Jim Ross Smith, John 

 R. Pugh, and Gerald E. Monan. April 1968, 

 iii -I- 11 pp., 6 figs., 6 tables. 



ABSTRACT 



The proposed installation of a fish collecting de- 

 vice in the upper end of Mossyrock Reservoir, soon 

 to be created on the Cowlitz River in southwestern 

 Washington, prompted this study to determine the 

 horizontal and vertical distribution of juvenile 

 salmonids in such an environment. A section of 

 the upper end of Mayfield Reservoir, an existing 

 body of water on the Cowlitz River, was systemat- 

 ically sampled with gill nets and a trawl from April 

 1964 to June 1965. Eighty-seven percent of the 

 11,467 salmonids captured were taken in the upper 

 7.3 m of water, which constituted 52.8 percent of 

 the total sampling area. 



If the distribution of fish in upper Mossyrock 

 Reservoir is similar to the distribution in Mayfield 

 Reservoir, a collecting device running from shore 

 to shore, extending to a depth of 7.3 m, and designed 

 to collect fish approaching from both the upstream 

 and the downstream sides should collect over 80 

 percent of all migrating salmonids. 



567. Setting and first season survival of the 

 American oyster, Crassostrea virginica, near 

 Oxford, Maryland, 1961-62, by J. R. Webster 

 and W. N. Shaw. July 1968, iii + 6 pp., 2 

 figs., 4 tables. 



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