Female reproductive output in the squid Loligo pealeii:multiple egg clutches and implications for a spawning strategy

Abstract

We examined actual and potential reproductive output with particular attention to the females' abilities to lay multiple clutches of eggs. Combining the results of 2 summer spawning seasons, 28 of 47 females that laid eggs in captivity produced substantial clutches (i.e., 5 or more egg capsules per clutch) at least twice. Multiply-ovipositing females exhibited a variety of patterns of oviposition, ranging from relatively small clutches at short intervals to large clutches several weeks apart. Actual reproductive output varied greatly between females. In both years, the number of egg capsules and ova laid showed a negative relationship with the combined mass of the ovary and oviduct at the time of death. Separate correlations between the number of ova laid and the combined number of oocytes and ova remaining in the reproductive tract at death revealed a similarly negative, although statistically weaker, relationship in both years. Most importantly, the number of ova laid in captivity (mean = 11 800 in 1997 and mean = 15 293 in 1998) exceeded the combined number of ova and oocytes remaining at death (mean ca 4500 in both years) by roughly 3x, providing an inhcation of the extent to which only counting remaining oocytes and ova can underestimate fecundity. The ages of ovipositing females spanned 4 to 6 mo. Interestingly, neither age nor mantle length consistently affected reproductive output, i.e., short young females could be just as fecund as longer older females. A supplementary feeding experiment failed to demonstrate an effect of feeding regime on captive lifespan or reproductive output. The females in one year (1998) were maintained in isolation without access to males; these females laid fertilized eggs, some over periods of 15 or more days, demonstrating the use of stored sperm. For females that had oviposited in both years, the oocytes remaining in the ovary always ranged greatly in size and structure. Thus, the 'spawning strategy' of Loligo pealeii appears to involve multiple ovipositions over weeks or months, with oocytes possibly being developed continually. Placing the results of this study in a larger context, reproduction by females in this and other loliginids most likely entails copulation with multiple males and the laying of multiple clutches of eggs, possibly in different locations.

Use of acoustic telemetry for spatial management of southern calamary Sepioteuthis australis, a highly mobile inshore squid species

“…Likewise, tagged Sepia apama remain in their aggregation area actively laying eggs for up to 6 wk (Hall & Hanlon 2002). Captive Loligo pealeii can spawn small clutches at short intervals or large clutches several weeks apart over durations of up to 50 d, with a big range in spawning frequency and output between captive females (Maxwell & Hanlon 2000).…”

“…The origin of these individuals is unclear, but they could potentially be individuals moving northward from Mercury Passage. Additionally, although multiple spawning is now recognized to be common among loliginid squids (Moltschaniwskyj 1995, Maxwell & Hanlon 2000) it has been difficult to assess the length of individual maturity in Sepioteuthis australis or any other species. Consequently, it is unknown how long spawning individuals are resident within the spawning regions, i.e.…”

Dependance of paternity rates on alternative reproductive behaviors in the squid Loligo bleekeri

“…A combined approach using both behavioral observations in the captive condition and genetic analysis can provide important information about the mechanism of sperm storage, release, and fertilization for each mating position (sperm storage site). Furthermore, previous studies analyzed only 1 or 2 egg capsules for each female even though females generally spawn many egg capsules (~20 to 100 in L. pealeii, Maxwell & Hanlon 2000). The utilization pattern of spermatozoa stored inside the mantle cavity and those stored in the seminal receptacle probably differ among egg capsules, so parentage analysis of all egg capsules spawned is needed to accurately determine the parentage rates of the different mating behaviors.…”

Pattern of Inheritance of Microsatellite Loci in the Squid Loligo pealeii (Mollusca: Cephalopoda)

“…Female A was kept in isolation in this tank for 48 hours. Female L. pealeii have no known organs for sperm storage within the mantle cavity (Drew, 1911), and Maxwell and Hanlon (2000) failed to find spermatophores within the mantle cavities of several females that had been kept in isolation for 1 or 2 days. Female A did not lay eggs during this isolation period.…”