Reproductive Characteristics of the Subtidal Hermit Crab Brandt, 1851 (Decapoda: Paguridae) from Peter the Great Bay, Sea of Japan

The reproductive characteristics of the subtidal hermit crab Brandt, 1851 from Peter the Great Bay (Sea of Japan) were studied based on material collected in 2014–2015 and 2023–2024. Within the depth range of 2 to 11 m, this hermit crab was encountered year-round, except in July and August, when it was either absent at these depths or represented by single individuals. The bulk of the population (over 90%) consisted of males with a shield length () of 8–18 mm and females with a of 7–13 mm. A peak in abundance was observed in April–May, primarily due to ovigerous females. Spawning in is asynchronous: ovigerous females were recorded from January to June and, in smaller numbers, in August. The presence of females that had recently laid eggs in August suggests a probable repeat spawning involving older size classes. The incubation period of the first generation eggs lasted from two to five months and ended in late May to early June. The development duration of the second generation eggs was likely about one month. The minimum (5.7–5.8 mm) of ovigerous females of corresponded to the second year of life. Individual fecundity in females with from 5.7 to 12.8 mm ranged from 2127 to 14 853 (with an average of 7984 ± 3320) eggs.