. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 392 WILLIAM C. SUMMERS AND JOHN J. McMAHON Survival of squid was averaged for the last observation in every 24 hour period for all runs resulting from a single method of capture. Figure 1 shows how the mean survival decreased with time and that the relative variation (standard deviation divided by the mean) increased with time for both trawl and trap caught squid. The mean survival of squid is shown on an absolute scale because the numbers of squid per run were kept within practical laboratory levels and there were insuffici
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 392 WILLIAM C. SUMMERS AND JOHN J. McMAHON Survival of squid was averaged for the last observation in every 24 hour period for all runs resulting from a single method of capture. Figure 1 shows how the mean survival decreased with time and that the relative variation (standard deviation divided by the mean) increased with time for both trawl and trap caught squid. The mean survival of squid is shown on an absolute scale because the numbers of squid per run were kept within practical laboratory levels and there were insufficient runs, in our opinion, to justify the use of a relative scale. The observed mean survival of squid appears to be proportional to the number of squid in the tank and similar for both methods of capture. The survival rate does not vary appreciably with time in the tank within one week. Least square fit proportional survival curves are shown as lighter lines in Figure 1, these corre- spond closely to a survival rate of 71% per day (, 50% every two days). More exactly, it was per day for trawl caught squid and per day for trap caught squid. Breeding activity and subsequent egg deposition is thought to cause rapid mortality in several species of cephalopods and is especially well documented for Loligo opalcscens (McGowen, 1954; Limbaugh and Shepard, 1957; Hobson, 1965; Fields, 1965). Thus, survival of immature squid versus breeding, sexually mature squid as well as survival of males versus females in the latter group is of interest. The similarity of relative survival rates for trawl caught squid (sexually mature and breeding) and trap caught squid (sexually immature) shown in Figure 1 indicates that no major differences exist between these groups over a period of one CAPTURE-TRAWL = 0 TRAP=« (8 RUNS) (4 RUNS). < tr LJ 3 4 TIME IN DAYS FIGURE 1. Mean survival of unfed squid, L. pcalci, in an aquarium over a period of one week. Dashed lines represent th
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