Port Phillip Bay is an important reproductive area for three shark species.

Fishing surveys and catch data have revealed the regular presence of neonate and young-of-the-year (YOY) Tope in the area since the 1940s (Olsen 1954, 1959; Stevens & West 1997; Walker et al. 2008). In southern Australia, this area was recognised as one of the six major nursery areas across Victoria and Tasmania for the species (Olsen 1954; Stevens & West 1997; Walker et al. 2008).

Between 1947–1953, 11 areas across Victoria and Tasmania were surveyed with handlines and gillnets to look for potential nursery areas for Tope (Olsen 1954). In Port Phillip Bay, 576 Tope measuring 27–50 cm total length (TL) were caught by handline. These individuals were classified as neonate/YOY. Reported size-at-birth for the species is 30–40 cm TL (Ebert et al. 2021) and YOY size in this region was set at 50 cm TL (Olsen 1954; Moulton et al. 1992). Port Phillip Bay was the area with the second largest number of neonate/YOY Tope recorded across all areas. Subsequently, between 1992–1996, three bays were also surveyed in Victoria to explore nursery areas for this species (Stevens & West 1997). In Port Phillip Bay, gillnet (n = 242, 75 m long gillnet) and longline (n = 92, 50 hook longline) sets were deployed in the area and 88 Tope were recorded mostly (81.8%) on longlines. Of these, 75 (85.2%) were classified as neonate/YOY based on their size and the rest were classified as one-year-old sharks (Stevens & West 1997). Port Phillip Bay recorded the second largest number of individuals and catch-per-unit-effort (CPUE) of these life-stages in Victoria after Western Port Bay. Neonate/YOY Tope were recorded mostly in summer, between December–March (Stevens & West 1997). Additional sampling was conducted in South Australia, but no neonate/YOY were recorded (Stevens & West 1997).

Population declines of Tope have been recorded since the 1950s across Australia including reductions of Tope pups in Port Phillip Bay (Walker 1999; Braccini et al. 2009). As part of regulations focused on population recovery, the use of nets has been prohibited in Port Phillip Bay since 2022 with limitations on catching Tope measuring <45 cm partial length (from the rear gill slit to the start of the tail) in this area (VFA 2023). In addition, seagrass degradation in this area following a drought from 1997 to 2010 has reduced the suitable habitat for early life-stage Tope (Jenkins et al. 2015). Existing regulations and the lack of surveys focused on monitoring neonate/YOY Tope are related with the reduction of contemporary records. However, records from recreational fishing forums between 2020–2023 have revealed that these life-stages are still incidentally caught in the area (Fishbrain 2025). These records confirm the contemporary importance of this area for reproductive purposes of this species. Despite the records of neonates and YOY, no pregnant females were recorded across all studies conducted in the area.

In the same monitoring from 1992–1996, 417 Gummy Sharks were caught in the area, mostly (60.2%, n = 251) on longlines (Stevens & West 1997). Of these, 137 (32.8%) were classified as neonate/YOY and 63 (16.1%) as one-year-old individuals. These individuals measured <45 cm TL which is close to the reported size-at-birth (30–35 cm TL; Ebert et al. 2021) and to the size set for YOY Gummy Sharks (50 cm TL) in the region (Moulton et al. 1992; Stevens & West 1997). Port Phillip Bay recorded the largest number of neonate/YOY and CPUE across all bays monitored in Victoria. As with Tope, existing regulations on the use of nets and size limits, and the lack of surveys focused on monitoring neonate/YOY Gummy Sharks are related to the shortage of contemporary records. However, records from recreational fishing forums since 2020 have revealed that these life-stages are still incidentally caught in the area (Fishbrain 2025). These records confirm the contemporary importance of this area for reproductive purposes of this species. Despite the records of neonates and YOY, no pregnant females were recorded across all studies conducted in the area.

Between November 2014–April 2015, 109 Broadnose Sevengill Sharks were caught with benthic longlines and rod-and-line (Schmidt-Roach 2018). Of these, 79 (73.1%) were classified as neonates/YOY (Schmidt-Roach 2018) as their size was smaller than the reported size for YOY in the region (<80 cm TL; Braccini et al. 2010). Almost all neonate/YOY were caught in March–April in the mid part of the bay. Sixty-one individuals were tagged with acoustic transmitters of which 43 were neonates. Broadnose Sevengill Sharks were monitored in an array of 46 receivers deployed across the entire bay between November 2014–January 2017. On average, individuals at early life-stages stayed ~80 days inside the area (3–469 days). Twelve neonates (28.5%) were detected leaving the area between June–July 2015, and 27 (64.3%) were detected after tagging and up to July 2015 but those were not detected leaving the area. Three neonates/YOY (7.1%) remained in Port Phillip Bay between nine months and one year. These individuals at early life-stages were detected mostly in the middle part of the bay at depths >20 m (Schmidt-Roach 2018). Six of the neonate/YOY tagged were detected on acoustic receivers or recaptured outside of this area, in locations around Victoria, New South Wales, and Tasmania, with the largest movement recorded to Maria Island in Tasmania (586 km from Port Phillip Bay) in 129 days. Port Phillip Bay is the only area in southern Australia that has been identified as a potential pupping and nursery area for the species (Schmidt-Roach 2018).