Environmental influence on life-history traits in male squid Uroteuthis edulis with alternative reproductive tactics

Abstract

Squid are characterized by flexible life-history traits (LHTs) that change in response to changing oceanic parameters. Male alternative reproductive tactics (ARTs), characterized by large-sized ‘consorts’ versus small-sized ‘sneakers’, are commonly observed in loliginid species. This study reports on LHTs flexibility in male squids displaying ARTs. LHTs of consorts and sneakers in Uroteuthis edulis, including body size, age, growth rate and gonado-somatic energy allocation, were compared among seasonal and geographical groups from Japan and Taiwan. The ratio of consorts to sneakers was highest in the group spawning in the ‘Japan-warm’ season (June–November), followed by that of the ‘Japan-cold’ season (December–May), and lowest in Taiwan (spring and autumn). LHTs were compared among cohorts separated by hatching season and catch location (Jwarm, Jcold and Taiwan cohorts). Mean body size of consorts showed no difference among cohorts, although Taiwan consorts were relatively younger than Japan consorts. Mean size and age of sneakers decreased with increased water temperature at hatching. Growth rates of consorts and sneakers were slightly different among cohorts, in accordance with differences of statolith increment widths during their early life stage (50–150 days). Growth rates of both consorts and sneakers were highest in the Taiwan cohort, followed by the Jwarm cohort, with the Jcold cohort lowest. Sneakers invested more both in mantle and gonadal weights than consorts in all cohorts. Gonado-somatic energy allocation patterns of consorts and sneakers were consistent at different temperatures. LHTs of U. edulis consorts and sneakers were strongly influenced by temperature, with higher flexibility in sneakers than consorts.

Population dynamics of two squid species, <em>Uroteuthis duvaucelii</em> (D'Orbigny, 1835) and <em>U. singhalensis</em> (Ortmann, 1891) (Family: Loliginidae) in the Trincomalee bay, Sri Lanka

“…Generally, spawning seasons in tropical fish stocks are longer than those in the temperate regions but encounter a 'survival window' that is open only during a short period (Bakun et al 1982;Pauly and Navaluna 1983), which may result in sharply peaked recruitment pulses. Despite the fact that the information about recruitment seasonality in squid stocks is scanty, they are known to exhibit considerable flexibility in life-history traits, which make them to adapt successfully to environmental changes (Doubleday et al 2016;Pang et al 2022). Recruitment patterns of the two squid species in the present study having a single peak can therefore be assumed to be due to such flexibility.…”

“…In the world fisheries, compared to finfish capture fisheries squids make a rather small contribution, but over the last decade, the proportion has increased steadily over, with some signs of recent leveling off (Arkhipkin et al 2015). One of the crucial factors contributing to the increase of squid stocks worldwide is assumed to be due to their considerable flexibility in life-history traits, which make them adapt successfully to environmental changes (Doubleday et al 2016;Pang et al 2022). In various squid species, considerable differences in life-history traits have been observed.…”

Ontogenetic growth responses to the environmental changes of the swordtip squid (Uroteuthis edulis) spring stock in the East China Sea

“…The weight of SSS showed a V‐shaped trend throughout the growth period of the spring stock (Figure 7). Salinity regulates the osmotic pressure balance of marine organisms and affects the related indicators of squids such as their reproductive development, growth metabolism, and energy rationing (Gaylard et al, 2020; Kako et al, 2016; Pang et al, 2022). Salinity and temperature are important factors in maintaining the balance between yolk uptake rate and yolk utilization rate in the embryonic stage, which determines the stock hatchability (Li et al, 2020; Natsukari et al, 1988; Pecl & Jackson, 2008).…”

“…Salinity and temperature are important factors in maintaining the balance between yolk uptake rate and yolk utilization rate in the embryonic stage, which determines the stock hatchability (Li et al, 2020; Natsukari et al, 1988; Pecl & Jackson, 2008). With the complete development of gonads and body size, squids need continuous feeding to reserve sufficient reproductive energy for mating and this process depends on osmotic pressure regulation (Pang et al, 2020, 2022). Therefore, salinity may affect organism physiological functions so that its weight is larger in the embryo–larval stage and adult stage.…”

“…In a suitable water temperature range, the hatching time of embryos decreases with the increase in temperature, whereas the growth rate of paralarvae increases with the increase in temperature (Pecl & Jackson, 2008; Pimentel et al, 2012; Yamaguchi et al, 2020). Therefore, water temperature allows the input allocation of energy accumulation to body growth and gonad development to be in a dynamic balance through the biochemical and physiological effects of squids (Kuan et al, 2022; Pang et al, 2020, 2022). However, individual metabolic costs continued to increase with the increase in temperature, so the growth rate in the adult stage gradually decreases (Pimentel et al, 2012; Rosa et al, 2014).…”