Evidence of Metapopulation Dynamics in Shortnose Sturgeon in the Southern Part of Their Range

Peterson, Douglas L.; Farrae, Daniel J.

doi:10.1080/00028487.2011.638584

Cited by 11 publications

(14 citation statements)

References 20 publications

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“…Interestingly, previous studies have documented similar patterns in other Shortnose Sturgeon populations. A recent study of Shortnose Sturgeon in the Ogeechee River, Georgia (Peterson and Farrae 2011), documented a comparable level of population variability from 2007 to 2009 (CV = 33.0%). Although Bain et al (2007) did not provide a quantitative estimate of variability in annual adult abundance, their data showed that adult abundance in the Hudson River Shortnose Sturgeon population was steady over the 4 years of their study.…”

Section: Discussionmentioning

confidence: 92%

Abundance and Size Structure of Shortnose Sturgeon in the Altamaha River, Georgia

Peterson

Bednarski

2013

Trans Am Fish Soc

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Endangered Shortnose Sturgeon Acipenser brevirostrum inhabit large tidal rivers along the Atlantic coastline of North America, ranging from the St. John River, Canada, southward to the St. Johns River, Florida. Currently, longterm assessments of the abundance and age structure of southern populations are completely lacking. To address this information gap, we assessed recent changes in Shortnose Sturgeon abundance and age structure by sampling with anchored entanglement gear in the Altamaha River, Georgia, during summer in 2004-2010. To estimate abundance, we used the Huggins closed-capture model in Program MARK. We assessed size structure by interpreting the first, second, and third quartiles of the FL of individuals captured during each year. In total, we captured 1,737 Shortnose Sturgeon (72 recaptures). Total estimated abundance was variable, ranging from 1,206 individuals (95% lognormal confidence interval [CI] = 566-2,759) in 2009 to 5,551 individuals (95% CI = 2,804-11,304) in 2006. Much of the annual variation in total abundance was attributable to wide variations in juvenile abundance, which ranged from a low of 62 individuals (95% CI = 24-181) in 2009 to a high of 3,467 individuals (95% CI = 1,744-7,095) in 2006. Annual shifts in size structure were indicative of rapid population turnover, probably resulting from a combination of mortality and permanent emigration. Although the Altamaha River Shortnose Sturgeon population shares several characteristics with northern populations (e.g., variable juvenile abundance and stable adult abundance), our results suggest that southern populations are more susceptible to decline because of their accelerated life cycle and inherently lower abundances.

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Section: Discussionmentioning

confidence: 92%

Abundance and Size Structure of Shortnose Sturgeon in the Altamaha River, Georgia

Peterson

Bednarski

2013

Trans Am Fish Soc

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“…However, genetic evidence indicates that the Ogeechee River population is closely related to that in the Altamaha River (Wirgin et al 2005). The probability of emigration from the Ogeechee population was estimated to be 0.16 (SE = 0.275) and the probability of immigrating was 0.84 (Peterson and Farrae 2011). Thus, the PVA model presented here should be expanded to describe these systems in tandem to account for potential "rescue effects" (Brown and Kodric-Brown 1977) in which extirpated populations may be recolonized by their neighbors.…”

Section: Small Coastal Rivers As Ecological Trapsmentioning

confidence: 96%

“…The spawning migration of Shortnose Sturgeon begins in late winter, but seems to follow different patterns in different rivers. In some rivers (e.g., the Hudson River), adults that are ready to spawn congregate downstream and migrate upstream together (Dovel 1981), and in other rivers, individuals migrate separately (Peterson and Farrae 2011). When the congregation option is simulated, all spawners join a group near a specified downstream location at the start of the breeding season.…”

Section: Reproductionmentioning

confidence: 99%

“…Locations used for spawning have not yet been confirmed in the Ogeechee River. Efforts to track three migrating adult females and 15 males were made during 1 year (Peterson and Farrae 2011). However, juveniles were occasionally sampled in earlier years (Fleming et al 2005).…”

Section: Small Coastal Rivers As Ecological Trapsmentioning

confidence: 99%

“…The Shortnose Sturgeon population in the Ogeechee River is smaller than those in the neighboring Savannah and Altamaha rivers, and is most closely related genetically to the Altamaha population (Quattro et al 2002;Wirgin et al 2005). Markrecapture estimates were between 25 and 275 individuals in the early 1990s (Rogers and Weber 1994), around 150 individuals in year 2000 (Fleming et al 2005), and between 200 and 450 individuals in (Peterson and Farrae 2011.…”

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A Population Model to Assess Influences on the Viability of the Shortnose Sturgeon Population in the Ogeechee River, Georgia

et al. 2013

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Southern populations of the federally endangered Shortnose Sturgeon Acipenser brevirostrum are considered to be at greater risk of extirpation than northern populations. Our study focused on the Ogeechee River, Georgia, a small, undeveloped, coastal river that supports a population with fewer than 300 Shortnose Sturgeon. We designed a population viability analysis (PVA) model to represent and quantify the demographic influences of three factors (poor water quality, intrusion of saline water via rice canals, and incidental harvest) on the viability of this population. As an isolated population, only 75% of simulated populations persisted beyond a 20‐year time horizon with all factors simulated. However, immigration from the Altamaha River may help to support the population. We quantified population persistence with and without simulating each factor and found that (1) incidental harvest had no effect on simulated persistence, (2) poor water quality decreased simulated persistence by 29%, primarily due to low oxygen conditions in summer, and (3) roughly one‐third of this effect was attributed to rice canals (premature exposure of juveniles to high salinities). Simulated recruitment to age 1 was limited by a habitat squeeze between density‐dependent starvation upstream near the spawning grounds and premature exposure to salinity downstream. These results highlight a need for research on availability of summer refuge and freshwater rearing habitat. As these results derived from a PVA model, which required many assumptions, they should be considered preliminary. Further field research is needed to confirm those results where it is possible to test intermediate predictions. We conclude by suggesting that efforts to maintain or increase the number of viable populations of Shortnose Sturgeon in southern U.S. rivers will probably require an understanding of (1) source‐sink dynamics between populations in rivers with access to adequate freshwater rearing habitat and those without, and (2) the effects of climate change.

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Long‐term trends in abundance and recruitment of Shortnose Sturgeon in the Altamaha River, Georgia

Kleinhans,

Fox

2024

Mar Coast Fish

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ObjectiveThe objective of this study was to estimate the population size and annual recruitment of Shortnose Sturgeon Accipenser brevirostrum in the Altamaha River estuary in Georgia, United States, during an 11‐year period. The Shortnose Sturgeon is an endangered fish species that occupies rivers on the east coast of North America. Previous studies have suggested that the Altamaha River supports the largest population of Shortnose Sturgeon in the southern United States; however, the status of the population has not been assessed in 11 years.MethodsWe used entanglement gears to capture Shortnose Sturgeon in the Altamaha River estuary, marked them, and used an established statistical method (closed‐population capture–mark–recapture models) to annually estimate total population size and age‐1 recruitment from 2012 to 2022.ResultWe were able to estimate the size of age‐1 cohorts in 7 of the 11 years of data collection. Point estimates of annual age‐1 recruitment varied between 113 and 1021 individuals, and total population size varied between 452 (95% confidence interval [CI]: 116–2277) and 5054 individuals (95% CI: 2155–13,267).ConclusionRecruitment of age‐1 juveniles was variable, suggesting that reproduction success is inconsistent between years in the Altamaha River. The results of this study, in combination with previous work, do not show any clear trends in Altamaha River Shortnose Sturgeon population abundance or recruitment. The population seems to be stable, but in the absence of historical population numbers, it is unclear whether the population should be considered recovered or is stagnated in its recovery.

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Evidence of Metapopulation Dynamics in Shortnose Sturgeon in the Southern Part of Their Range

Cited by 11 publications

References 20 publications

Abundance and Size Structure of Shortnose Sturgeon in the Altamaha River, Georgia

Abundance and Size Structure of Shortnose Sturgeon in the Altamaha River, Georgia

A Population Model to Assess Influences on the Viability of the Shortnose Sturgeon Population in the Ogeechee River, Georgia

Long‐term trends in abundance and recruitment of Shortnose Sturgeon in the Altamaha River, Georgia

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