Reproduction occurs from October[2] to March.[3] In February, the population of C. propinquus greatly increases.[4] During this time, the population is mostly concentrated in the top 150 metres (490 ft) of the sea. The next month, the population shifts, with stages I through III found from sea level to 25 metres (82 ft) in depth. The females, on the other hand, are usually found deeper than 500 metres (1,600 ft).[3] In the Southern Hemisphere autumn, some stage III through V copepodites migrate to overwinter below depths of 200 metres (660 ft) (probably in diapause). Most of these copepodites, however, stay at the surface, overwintering in an active state.[5] During October and November, most of the population is found between 100 and 500 metres (330 and 1,640 ft) of depth.[4]
The lipid content of this species changes throughout its lifecycle. The highest concentration of lipids are found in adults, with lipids making up about 40%, on average, of the dry weight of females during the summer.[6] It has the highest lipid content during the autumn, and the lowest during the spring. These stores decrease as its gonads develop.[2] Most of the accumulated lipids are triglycerides, contrasting with other calanoid copepods that primarily use wax esters.[6] This is partially achieved through the elongation of 11-Eicosenoic acid into erucic acid, which serves to concentrate the energy found.[7] C. propinquue primarily uses triglycerides likely because most individuals are active during winter.[5] The percentage of lipids that are triglycerides increases as the copepod ages; about 42% of the lipids in stage II copepodites are triglycerides, whereas in females, this increases to about 91% of the total lipid content.[6]
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