Diversity in Habitat Use by White Sturgeon Revealed Using Fin Ray Geochemistry

Abstract

Understanding life-history diversity in a population is imperative to developing effective fisheries management and conservation practices, particularly in degraded environments with high environmental variability. Here, we examined variation in habitat use and migration patterns of White Sturgeon (Acipenser transmontanus), a long-lived migratory fish that is native to the San Francisco Estuary, CA, United States. Annual increment profiles were combined with respective geochemical (87Sr/86Sr) profiles in sturgeon fin rays to reconstruct annual salinity chronologies for 112 individuals from 5 to 30 years old. Results indicated a complex and diverse amphidromous life history across individuals, characterized largely by estuarine residence, a general ontogenetic trend toward higher-salinity brackish habitats, and high variability in habitat use across all age groups. Hierarchical clustering based on fin ray geochemistry during the first 10 years of life, prior to sexual maturation, indicated at least four distinct migratory phenotypes which differed largely in the timing and duration of juvenile to subadult movements between fresh- and brackish-water habitats. This study provides information regarding habitat use and migration in sub-adult fish that was previously lacking. Different migratory phenotypes vary in exposure to stressors across time and space and populations. Understanding White Sturgeon habitat distributions through space and time at different life stages can help identify areas where habitat restoration would be most effective and develop management actions to reduce stressors associated with specific areas where White Sturgeon are present.

Habitat use differences mediate anthropogenic threat exposure in white sturgeon

“…Groups of shortnose sturgeon ( Acipenser brevirostrum ) inhabiting coastal waters and river systems of Maine also exhibit divergent patterns of movement and habitat use (Dionne et al 2013; Altenritter et al 2018), and in the same Sacramento River system green sturgeon ( Acipenser medirostris ) exhibit distinctly bimodal early/late downriver migration patterns (Colborne et al 2022). Sellheim et al (2022) found evidence for groups of white sturgeon from the same population as this study exhibiting distinct patterns of habitat use with age. Intraspecific variation in habitat occupancy and migration behavior could be a common and linking feature of sturgeon ecology more generally (Miller et al 2020).…”

“…For lake sturgeon, habitat use patterns were generally consistent over time, suggesting that sturgeon habitat use groups reflect individuals' intrinsic preferences or specialization, possibly influenced by life history factors. Groups of shortnose sturgeon (Acipenser brevirostrum) inhabiting coastal waters and river systems of Maine also exhibit divergent patterns of movement and habitat use(Dionne et al 2013;Altenritter et al 2018), and in the same Sacramento River system green sturgeon (Acipenser medirostris) exhibit distinctly bimodal early/late downriver migration patterns(Colborne et al 2022) Sellheim et al (2022). found evidence for groups of white sturgeon from the same population as this study exhibiting distinct patterns of habitat use with age.…”

“…(2019), which Sellheim et al (2022) indicate would tend to be using higher-salinity habitats. The discrepancy in ages between these studies also highlights that telemetry data on juvenile white sturgeon are limited, resulting in uncertainty over their habitat use and movements.…”

“…Fish in this age range are below the slot limit, and below-slot fish, in our study, tended to be found lowest in the system, in areas tending toward higher salinity, compared with larger fish. Note that the youngest fish in our dataset was estimated at 7 years old based on the growth curve presented in Blackburn et al (2019), which Sellheim et al (2022) indicate would tend to be using higher-salinity habitats. The discrepancy in ages between these studies also highlights that telemetry data on juvenile white sturgeon are limited, resulting in uncertainty over their habitat use and movements.…”

“…In the San Francisco Estuary and Sacramento River system, white sturgeon at different size classes exhibit variable patterns of habitat use. Differentiated patterns of habitat use and movement within populations appear to be a common feature of sturgeon biology across related species (Dionne et al 2013;Kessel et al 2018;Altenritter et al 2018;Colborne et al 2019Colborne et al , 2022Sellheim et al 2022). Further study is needed to resolve the biological underpinnings and implications for population health and management.…”