613. Sea-Bottom Photographs and Macroben- 

 thos Collections from the Continental Shelf 

 off Massachusetts. By Roland L. Wigley and 

 Roger B. Theroux. August 1970, iii + 12 pp., 

 8 figs., 2 tables. 



ABSTRACT 



Epibenthic invertebrate animals were sampled 

 with a large scallop dredge and photographed with 

 a sled-mounted camera at four locations on the 

 Continental Shelf off Massachusetts in August 1965. 

 Sea-bottom photographs taken at a station south 

 of Martha's Vineyard, Mass., at a depth of 59 m. 

 revealed a sandy silt sediment with a slightly 

 uneven microtopogi'aphy. At three stations on south- 

 eastern Georges Bank, at 64 to 82 ni., sediments 

 were predominantly sand with small proportions of 

 shell fragments and silt. The microtopography was 

 generally rough and irregular, largely caused by 

 feeding of fish and other biological activity. Sand 

 ripples were common; some apparently formed by 

 wave action and others by tidal currents. 



Species composition of the large epibenthic in- 

 vertebrates was similar at the three localities on 

 Georges Bank but differed markedly from that south 

 of Martha's Vineyard. Also, the number of speci- 

 mens were substantially higher on Georges Bank 

 than south of Martha's Vineyard. The densities of 

 invertebrates estimated from photographs (0.7, 1.7, 

 1.8, and 8.6 individuals per square meter) at the four 

 stations were substantially higher than estimates 

 based on the dredge collections (0.02, 0.16, 0.3 and 

 3.3 individuals per square meter). 



614. A Sled -Mounted Suction Sampler for Ben- 



thic Organisms. By Donald M. Allen and J. 



Harold Hudson. August 1970, iii + 5 pp., 5 



figs., 1 table. 



ABSTRACT 



The sampler is an underwater vacuum device 

 mounted on a sled; a venturi-type water dredge 

 provides suction. This equipment collects quantita- 

 tive samples of young pink shrimp, Poicu-nt: ditora- 

 )it>ii diioranoii, and is effective in capturing other 

 small benthic organisms. 



615. Distribution of Fishing Effort and Catches 

 of Skipjack Tuna, Katt^uwoiiiis pelaniis, in 

 Hawaiian Waters, by Quarters of the Year, 

 1948-65. By Richard N. Uchida. June 1970, 

 iv + 37 pp., 6 figs., 22 tables. 



ABSTRACT 

 The temporal and spatial distribution of fishing 

 effort and skipjack tuna catches are described on 

 the basis of detailed data on catch, location, and 

 effort obtained each year from all vessels that fish 

 full time for skipjack tuna in Hawaiian waters. 

 Summarized are the amount of "effective" fishing 

 (defined as a trip on which skipjack tuna are caught), 

 the resulting catch, and catch per standard effective 

 trip in each statistical area and combinations of 



statistical areas (regions). 



The fishing is highly seasonal. Usually the effort 

 expended and the catch in the first quarter were 

 15 and 9 percent, respectively, of their annual 

 totals. Fishing intensified in May and second quarter 

 catches, produced by 32 percent of the annual effort, 

 accounted for 33 percent of the annual catch. .■^ 

 further increase in effort to 36 percent of the annual 

 total in the third quarter increased catches sharply 

 so that they constituted 46 percent of the annual 

 take. As the abundance of skipjack tuna declined in 

 the fall, fishing also declined; fourth quarter effort, 

 which was reduced to 17 percent of the annual total, 

 produced only 12 percent of the annual catch. 



616. Effect of Quality of the Spawning Bed on 

 Growth and Development of Pink Salmon 

 Embryos and Alevins. By Ralph A. Wells and 

 William J. McNeil. August 1970, iii + 6 pp., 



4 tables. 



ABSTRACT 



Among three segments of the spawning ground in 

 Sashin Creek, southeastern Alaska, the largest and 

 fastest developing embryos and alevins of pink 

 salmon, Oticorhyiichus gorbitscha, came from spawn- 

 ing gi-avels characterized by high levels of dissolved 

 oxygen in intragi-avel water. The high oxygen 

 levels occurred in a stream segment which has a 

 relatively steep grade and coarse materials in the 

 bed. No differences in water temperature were ob- 

 served among the three segments. 



617. Fur Seal Investigations, 1968. By NMFS, 

 Marine Mammal Biological Laboratory. De- 

 cember 1970, iii + 125 pp., 32 figs., 53 tables, 



99 app. tables. 



ABSTRACT 



Field investigations in 1968 were made on the 

 Pribilof Islands from June to October, in Washing- 

 ton waters in November-December 1967 and Janu- 

 ary-February 1968. and in Alaska waters from May 

 to August 1968. Data wei'e collected during these 

 periods for studies of population levels and the 

 maximum sustained yield, and the distribution, 

 feeding habits, migrations, and pregnancy rates 

 of fur seals. 



In 1968, 45,625 male and 13,335 female fur seals 

 iCatlorhiniis ursiniis) were killed on the Pribilof 

 Islands. 



Dead fur seals counted included 31,438 pups and 

 350 animals older than pups. The major causes of 

 death among 379 pups were malnutrition, hook- 

 worm disease, trauma, infections, and perinatal 

 comple.\. 



We estimated that the Islands had 7,924 harem 

 and 4,383 idle males in mid-July. 



Pregnancy rates of females were 42 percent for 

 1,058 from hauling gi-ounds in 1968 and 100 percent 

 for 221 from rookeries in 1957. 



The average weights of the pups were 9.6 kg. for 

 males and 8.3 kg. for females. Seals tagged included 



17 



