Abstract:
Research cruises were made between August 28, 1967, and June 19, 1968,
to study the vertical distribution and movements of pink shrimp, Pandalus
jordani, off Tillamook Head in 68-80 fathoms. Shrimp traps suspended from
surface to bottom, midwater trawl, and bottom shrimp trawl nets were used.
Results are discussed in general terms and problems encountered are described.
Shrimp were found to migrate off bottom rapidly at night. No apparent
correlation between moon phase and migration was indicated. Data on moon
phase-migration pattern are limited, however, due to weather and/or cloudy
conditions. Seasonal d5fferences in vertical migration in the study area
(sex composition and height of migration) were indicated, probably due to
(1) sex segregation and 2) presence or absence of thermocline. Few shrimp
were caught in pots during May and June 1968, possibly due to a change in
feeding habits. Differences in sex composition of catches in pots and
midwater trawl indicate the pots are probably biased toward catching females.
These data await detailed analysis. Results will appear in a final report on
this study next year.
