Jervis Bay is an important reproductive area for one shark and one ray species.

This area has been documented as a regular and predictable breeding site for Port Jackson Sharks since the 1960s. Historic SCUBA diving surveys, fisheries capture records, and external tagging programs in the 1960s and 1970s identified that Port Jackson Sharks gathered on nearshore rocky reefs in sheltered bays and inlets every year during the austral winter and autumn (June–November) along the east coast of Australia at ‘traditional oviposition sites’ (McLaughlin & O’Gower 1971; O’Gower & Nash 1978). An in-depth analysis of the reproductive status of Port Jackson Sharks during the breeding aggregation period, including sharks sampled from within Jervis Bay, found that females were in reproductive condition (mature oocytes) from July–October and ultimately lay eggs throughout that period (Powter & Gladstone 2008). It has been speculated that Port Jackson Sharks develop an extensive mental map of their breeding aggregation locations (O’Gower 1995). Acoustic telemetry tracking data using 10-year transmitters show that males arrive and depart Jervis Bay two weeks earlier than females (Martin-Podevin et al. 2025), and the peak breeding period is July to November (Bass et al. 2016). These data show that both males and females return to the same reef within Jervis Bay every year, with an average year-to-year return rate of 77% (Bass et al. 2021). A repeatability analysis of migration timing was conducted and found that over a 7-year period, the individual repeatability scores for arrival and departure were 0.51 and 0.40, respectively (Martin-Podevin et al. 2025). The long-term nature of these tags (10-year deployments) demonstrated prolonged use of the same locations in the area, by the same individuals over multiple years, and confirm that the same traditional breeding locations historically identified are still used. In addition, anecdotal observations of Port Jackson Shark breeding behaviours have been reported in the area and include courtship, mating, and egg laying (C Brown & J Pini-Fitzsimmons pers. obs. 2025). The bay represents one of only three known breeding aggregation sites for Port Jackson Sharks along the New South Wales coast (the other two are Port Stephens and Sydney Harbour to the north of the area), confirming its importance for reproduction for this species.

Jervis Bay serves as a gestating area for female Smooth Stingrays. The population within the bay is strongly adult female biased, a pattern consistent across multiple years of acoustic tracking and behavioural observations (2017–2022), with the majority of females present across multiple years (Pini-Fitzsimmons et al. 2018, 2023; Pini-Fitzsimmons 2022). During late winter and spring, adult females are frequently observed from the shore as mid- to late-stage pregnant (~75% of all observations are of pregnant females; J Pini-Fitzsimmons unpubl. data 2025), evidenced by their visibly extended abdomens, indicating that the bay provides a safe area for gestating females. Tracking of 35 female Smooth Stingrays tagged within Jervis Bay across three years (2017–2019) has revealed strong seasonal patterns of habitat use. Individuals are most likely to be present within the bay during late winter and early spring (August–September) and more likely to be absent during summer to early autumn (February–March; Beck 2022). These absences coincided with detections at the mouth of the bay, including both short-term departures and longer absences exceeding one month (Beck 2022). Some females were >200 km along the New South Wales coast before returning to the bay, suggesting the use of broader coastal habitats during these periods (Beck 2022). While the precise function of these departures is unknown, it is hypothesised that this is for the purpose of pupping and subsequent mating. A study in New Zealand documented seasonal offshore breeding aggregations of Smooth Stingrays during the austral summer (Le Port & Lavery 2012), and in Jervis Bay, seasonal movements from inshore to coastal habitats corresponded with spring–summer. One female tracked from Jervis Bay was documented returning to the bay with fresh mating wounds following a ~3-week departure in late-spring (Pini-Fitzsimmons 2022), and long-term monitoring indicates the highest frequency of mating wounds on females within Jervis Bay occurs during spring–summer (J Pini-Fitzsimmons unpubl. data 2025).

In contrast, males are rarely recorded within the bay; only three males have been sighted and tracked compared to 35 females tagged over six years, despite targeted research in the area and concerted efforts to tag and track males (Beck 2022; Pini-Fitzsimmons 2022). This observation is consistent with male-biased dispersal patterns reported for Smooth Stingrays (Roycroft et al. 2019), whereby males are likely more transient than females. Collectively, these findings indicate that Jervis Bay functions as a gestating area for female Smooth Stingrays. Females remain within the bay for most of the year before undertaking seasonal movements outside the bay, likely to seek mating opportunities with more transient males (J Pini-Fitzsimmons pers. obs. 2025). The combination of the observed female-biased population, pregnant individuals, and seasonal absences linked to pupping demonstrates that Jervis Bay is especially important for Smooth Stingray reproduction relative to surrounding areas.