Prince William Sound is important for undefined aggregations of two shark species.

Fishing surveys, satellite and acoustic telemetry, and aerial surveys have revealed the regular and predictable occurrence of Salmon Shark aggregations in the area. Aerial surveys conducted in 1998–1999 documenting Pacific Herring Clupea pallasii spawning events recorded up to 100 Salmon Sharks at single events inside the area (A Carlisle et al. unpubl. data 2026). Aggregations have also been recorded through capture and tagging efforts, and tourism activities in the region. During tagging experiments, up to 13 individuals were recorded in a single day in Port Gravina (inside the area; A Carlisle et al. unpubl. data 2026) and tourism efforts have reported groups of 4–5 individuals hunting in the same area or swimming at the surface (Alaska Sharks pers. comm. 2026; Big Fish Expeditions pers. comm. 2026). Between 2002–2024, 128 adult female Salmon Sharks were tagged in this area with satellite transmitters to study their habitat use in Prince William Sound and the surrounding Gulf of Alaska region (Weng et al. 2008; Arnoldi et al. 2024). Tagged individuals spent the summer and autumn months of their migration cycle in the area likely foraging on Pacific salmon, Alaska Pollock Gadus chalcogrammus, and Pacific Herring (Weng et al. 2005; Carlisle et al. 2015; Coffey et al. 2017), with a particular focus on adult salmon which return to the streams, rivers, and hatcheries in July and August (Hulbert & Rice 2002). While most mature females migrate south out of the Gulf of Alaska into the California Current system in autumn months (86%; 88 of 102 individuals tracked for >1 month), some individuals were documented overwintering in the area (Weng et al. 2005; Coffey et al. 2017). Kernel utilization density (KUD) estimates from satellite tags show high density of detections in the area further confirming habitat use, with long-term tagged and tracked individuals showing repeated returns to the area across multiple years of migration (Arnoldi et al. 2024; S Daley et al. unpubl. data 2026). Acoustic telemetry of 24 individuals monitored between 2008–2009 showed that Salmon Sharks aggregate in the area with a higher residency in August when 20 individuals (83.3%) were continuously recorded.

Aggregations of Pacific Sleeper Sharks have been regularly recorded in the area. Between 1998–2025, the International Pacific Halibut Commission (IPHC) conducted annual longline surveys during summer (June–August) across nearshore and offshore waters from Southern California to Alaskan waters (Gulf of Alaska, Aleutian Islands, and Bering Sea; IPHC 2026a). Surveys were conducted at ~1,200 stations each year at depths of 15–503 m. Longlines consisted of 4–8 skates (longline units) with 96–104 hooks per skate with soak times between 5–24 hours (IPHC 2026b). Non-halibut species were counted either as subsample counts (20% of observations, where the majority for sharks are considered) and whole-haul counts (100% observations). Nominal catch-per-unit-effort (CPUE) was estimated as the number of individuals caught per 100 hooks per hour.

During this period, Pacific Sleeper Sharks were recorded in 3,455 sets during longline surveys, of which 196 (5.7%) sets were recorded inside the area during the months of June–August across all surveyed years and at depths of 32–263 m (IPHC 2026a). Individuals were counted in subsamples (20% of the observations) in 3,292 sets (95.3% of total) suggesting that abundances reported reflect an underestimate of the total catches for this species in this fishery. The highest mean CPUE of Pacific Sleeper Sharks in the region was reported from this area (mean = 0.09 individuals/100 hooks/hour; 0.008–0.390) compared to adjacent areas in the region (mean CPUE outside the area = 0.05 individuals/100 hooks/hour; 0.004–0.450). Multiple individuals (>10) were recorded in 32 sets (16.3% of the sets with the species captured inside this area) with 29 individuals being the maximum number recorded in a single set (mean = 5.5 individuals/set). In addition, this area has been highlighted as important to Pacific Sleeper Sharks due to the large catches (biomass) of individuals, according to commercial fisheries data collated from non-pelagic trawl gears (Tribuzio et al. 2022). High abundances for Pacific Sleeper Sharks have been associated with aggregations of the species, here and elsewhere (Matta et al. 2024). In addition, 14 individuals were tagged with satellite transmitters in the southern end of the fjord system near Whittier, Alaska, and Cochrane Bay within the area between June–August 2022. All mark-report tags popped up inside the area suggesting that tracked Pacific Sleeper Sharks remained in the fjord system year-round (Bishop et al. 2026). The horizontal and vertical seasonal movements of tracked Pacific Sleeper Sharks suggest that they may shift from pelagic foraging to benthic scavenging and also balance foraging with resting (Bishop et al. 2026).

Further information is required to understand the nature and function of these aggregations.