Macewicz et al.: Fecundity, egg deposition, and mortality of Loligo opa/scens 



315 



A 129-mmL. opalescens with a potential fecundity of 3844 

 oocytes would have a maximum fecundity of 3010 eggs 

 (3844-834 eggs) or about 78% of the potential fecundity. 

 Very few females would be expected to deposit 78% of 

 their potential because this maximum is based on extreme 

 values for both mantle condition index and ovarian matu- 

 ration. In a much larger set of mantle samples from the 

 catch (Table 4), only 1.5% of the females had values of 

 C less than 0.35 mg/mm-. Clearly very few squid live to 

 deposit 78% of their potential fecundity. 



Another approach is to count the number of oocytes 

 remaining in the ovaries of females presumed, from their 

 behavior and appearance, to be dying. Although L. opal- 

 escens has been observed to be dying or dead on the bot- 

 tom on video from a remotely operated vehicle (Cossio 1 ), 

 capturing such females was not attempted at the time. A 

 female L. opalescens (136 mm) believed to be dying was 

 opportunistically collected by a diver 6 July 2000 on the 

 La Jolla Canyon spawning grounds (McGowan, 1954). 

 There were no ova and the ovary contained 1487 oocytes — 

 substantially more oocytes than our estimate of the mini- 

 mum residual fecundity. In fact, the female had deposited 

 only about 63% of her potential fecundity. 



Role of body reserves 



We used weight relationships to evaluate the extent to 

 which body reserves might be used to support the repro- 

 duction of spawning female L. opalescens. In these crude 

 energetic calculations we did not include metabolism, 

 conversion efficiencies, or caloric values of tissues. We 

 used the average dry weight of squid eggs, length to body 

 weight conversion, potential fecundity equation, and 

 the conversion factor from wet to dry mantle weight. We 

 assumed preovulatory mantle condition index (C) for an 

 average mature female of 130 mm was 0.798 mg/mm 2 , 

 the mean for values (/!=41) of C > 0.700 mg/mm 2 in the 



1 Cossio, A. 2000. Personal commun. Southwest Fisheries 

 Science Center, National Marine Fisheries Service. 8604 La 

 Jolla Shores Dr., La Jolla, CA 92037 



our fecundity data set. We calculated that the potential 

 fecundity of a 130-mm L. opalescens (i.e., 3874 encapsu- 

 lated eggs) has a dry weight of 6.86 g which is equivalent 

 to 64.8% of the whole-body dry weight (10.58 g) of that 

 female just before spawning. If mantle condition is reduced 

 in proportion to the dry weight of all the eggs, our hypo- 

 thetical female would have a C of about 0.281mg/mm 2 

 (0.798x[(10.58-6.86)/10.58]). This end point (C=0.281, 

 egg=0) and the beginning point for the mature preovula- 

 tory female (C=0.798, eggs=3874) create a hypothetical 



