Long Beach & Huntington Beach is an important reproductive area for one shark and one ray species.

Data from fishery catches, satellite and acoustic telemetry monitoring, unmanned aerial vehicle (UAV) surveys, and environmental DNA (eDNA) surveys have confirmed the regular presence of White Sharks in the area (Lowe et al. 2012; Anderson et al. 2021; Rex et al. 2023; McCauley et al. 2024; Merson et al. 2025). These data indicate that southern California contains spatiotemporally dynamic centres of primary and secondary nursery habitat for young-of-the-year (YOY) and juvenile White Sharks. Juveniles form aggregations at locations that are inter-annually variable along the coast, with individuals exhibiting increased site fidelity, residency levels, and spatially restricted movements for periods up to eight years (Anderson et al. 2021). Long Beach & Huntington Beach represents one of the largest and interannually most reliable sites in which YOY and juvenile White Shark aggregations are regularly and predictably observed (Lowe et al. 2012; Anderson et al. 2021; Rex et al. 2023).

Catch data from multiple fisheries operating in nearshore waters between 1936–2009 revealed that the broader area of the Southern California Bight is a nursery area for White Sharks (Lowe et al. 2012). Of 369 records, 39% (n = 144) were neonate/YOY measuring <175 cm total length (TL; Cailliet et al. 1985; Malcolm et al. 2001), 21% (n = 77) were juveniles, 5% (n = 18) were adults, and the rest were of unreported size. Inside the Southern California Bight, Long Beach & Huntington Beach was identified as a hotspot for catches of YOY and juvenile White Sharks especially during the summer (Lowe et al. 2012).

Between 2010–2026, the California State University – Long Beach (CSULB) Shark Lab tagged 378 White Sharks across southern California. Of these, 40 (10.6%) were neonate (<150 cm TL; Ebert et al. 2021), 61 (16.1%) were YOY, and 243 (64.3%) were juveniles at the time of tagging (CSULB Shark Lab unpubl. data 2026). In Long Beach & Huntington Beach, only seven YOY/juvenile White Sharks were tagged with tagging effort being lower here compared to other areas across the California coast. However, 77 YOY and juvenile White Sharks tagged in other locations were detected 481,153 times from 2010 to 2026 highlighting the area as a hotspot for these early life-stages (CSULB Shark Lab unpubl. data 2026). This area holds a large abundance of the main prey for early life-stage White Sharks (benthic sharks, rays, and bony fishes) compared to other areas across southern California (Jahn 2024).

Data from beach seines surveys, underwater visual census, acoustic telemetry, aerial drone surveys, and recreational fishing records gathered between 1998–2026 indicate that Haller’s Round Ray aggregations occur regularly in the area (Hoisington & Lowe 2005; Vaudo & Lowe 2006; Lowe et al. 2007; Jirik & Lowe 2012; Lyons & Lowe 2013; Jahn 2024). Aggregations of up to 1,000 individuals are present in the area, mostly between June–August around Seal Beach and Belmont, near the mouth of the San Gabriel River and up to 30 m from the shore, with abundances decreasing after periods of high wave activity (Hoisington & Lowe 2005; Vaudo & Lowe 2006; Lowe et al. 2007). Aggregations are composed mostly of mature individuals and while males are more abundant year-round, female aggregations are more abundant in July and August. These are the reported months for pupping (Jirik & Lowe 2012) as confirmed by dissection of near-term pregnant females (Lyons & Lowe 2013). Pregnancy has been confirmed in most of the females sampled across multiple studies using ultrasounds (all females sampled), dissection, and steroid hormone levels (Mull et al. 2008, 2010; Jirik & Lowe 2012; Lyons & Lowe 2013). Aggregations of pregnant female Haller’s Round Rays occur in the summer through fall, where warm shallow waters may provide thermal reproductive benefits including shorter gestation periods, larger offspring, and higher offspring survival rates (Jirik & Lowe 2012; Lyons & Lowe 2013). Male abundances peak during the spring, likely present to mate, before vacating during peak warm water months (Jirik & Lowe 2012) as confirmed by testosterone levels (Mull et al. 2008). In addition, neonates and YOY have been recorded in small numbers (compared to adults) in beach seines based on their size <8.1 cm disc width (DW) as the reported size-at-birth is 6–8 cm DW (Last et al. 2016) and confirmed by age-and-growth studies (Hale & Lowe 2008). These early life-stages have been recorded year-round (Hale & Lowe 2008). Recent beach seine surveys during 2022–2023 have been recording these adult aggregations of hundreds of individuals indicating pregnant females still occur in the area (Jahn 2024; CSULB Shark lab unpubl. data 2025).