Observer Accuracy and Precision in Aerial and Foot Survey Counts of Pink Salmon in a Southeast Alaska Stream

Jones, Edgar; Quinn, Terrance J.; Alen, Benjamin W. Van

doi:10.1577/1548-8675(1998)018<0832:oaapia>2.0.co;2

Cited by 28 publications

(28 citation statements)

References 10 publications

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“…Moreover, we did not detect an effect of seed quantity on recovery rates of seeds. Multiple observers can represent a significant source of variability and nonrecovery of seeds can lead to negative biases in count data (Caughley 1974, Sauer et al 1994, Jones et al 1998). However, multiple observers are often required to collect data and process samples due to temporal or logistical limitations of field studies.…”

Section: Discussionmentioning

confidence: 99%

Estimation and correction of seed recovery bias from moist‐soil cores

2011

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Scientists estimate seed abundances to calculate seasonal carrying capacities and assess wetland management actions for waterfowl and other wildlife using soil core samples. We evaluated recovery of known quantities of moist‐soil seeds from whole and subsampled experimental core samples containing 12 seed taxa representing small, medium, and large size classes. We recovered 86.3% (SE = 1.8) of all seeds added to experimental cores; 8.3% (SE = 1.2) of seeds were destroyed during the sieving process and 5.4% (SE = 1.2) were not recovered by observers. Recovery rates varied by seed size, but not seed quantity or disproportionate ratios of seed‐size classes. Overall seed recovery rates were similar between subsampled (${\bar {x}}$ = 81.2%, SE = 3.6) and whole–processed core samples (${\bar {x}}$ = 86.3%, SE = 1.8). We used recovery rates to generate size‐specific, taxon‐specific, and constant correction factors and applied each to actual core sample data. Size‐specific correction factors increased seed mass estimates in the Mississippi Alluvial Valley (${\bar {x}}$ = 10.1%, SE = 0.32), upper Midwest (${\bar {x}}$ = 21.2%, SE = 0.61), and both regions combined (${\bar {x}}$ = 15.7%, SE = 0.51) differently, as seed composition in core samples varied regionally. We suggest scientists consider using size‐specific correction factors to account for seed recovery bias in core samples because these factors may be applied to a variety of taxa and produced similar mass estimates as taxon‐specific correction factors. However, if data from core samples are unavailable at the resolution of seed size classes, we suggest increasing seed mass estimates by 16% to account for seed recovery bias. © 2011 The Wildlife Society.

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Section: Discussionmentioning

confidence: 99%

Estimation and correction of seed recovery bias from moist‐soil cores

2011

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“…However, doubling the abundance estimates of pink salmon (which is a common correction factor for peak count data; Jones and McPherson , Jones et al. ) prior to 1998 did not significantly affect our results. Given that pink salmon abundance estimates over the four decades of this system ranged from less than 1000 to over 100,000, we suggest that the signal‐to‐noise ratio of these data are robust to potential observation error and potential bias in pink salmon abundance estimates.…”

Section: Methodsmentioning

confidence: 54%

The roles of extrinsic and intrinsic factors in the freshwater life‐history dynamics of a migratory salmonid

et al. 2018

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Key life‐cycle transitions, such as metamorphosis or migration, can be altered by a variety of external factors, such as climate variation, strong species interactions, and management intervention, or modulated by density dependence. Given that these life‐history transitions can influence population dynamics, understanding the simultaneous effects of intrinsic and extrinsic controls on life‐history expression is particularly relevant for species of management or conservation importance. Here, we examined how life histories of steelhead (Oncorhynchus mykiss) are affected by weather, pink salmon abundance (Oncorhynchus gorbuscha), experimental nutrient addition, and density‐dependent processes. We tested for impacts on the size of steelhead smolts (juveniles migrating to the sea), as well as their age and abundance across four decades in the Keogh River, British Columbia, Canada. Larger steelhead smolts were associated with warmer years and artificial nutrient addition. In addition, higher pink salmon abundance and artificial nutrient addition correlated with juvenile steelhead migrating at younger ages. While density dependence appeared to be the primary factor regulating the abundance of steelhead smolts, nutrient addition and temperature were positively and negatively associated with smolt production, respectively, prior to 1991, and pink salmon spawning abundance was positively associated with smolt production after 1990. Thus, this study provides evidence that the temporal dynamics of one species of salmon is linked to the juvenile life history of co‐occurring steelhead. A complex interplay of species interactions, nutrient subsidies, density dependence, and climatic variation can control the life‐history expression of species with complex life cycles.

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“…Populations with small effective sizes diverge more quickly than larger populations, and each of the Wood River system streams likely had a population size of <100 individuals based on field observations of their absolute numbers, which averaged fewer than 10 individuals per kilometre of habitat (Pess 2009). Process and observation error associated with visual surveys may have biased our estimates of Wood River system chum and Chinook salmon population sizes downward (see Jones et al 1998). Chum and Chinook salmon are larger-bodied and have distinct coloration from sockeye salmon, making them noticeable in the field, but they would have been missed if they arrived after the surveys.…”

Section: Discussionmentioning

confidence: 99%

Self-sustaining populations, population sinks or aggregates of strays: chum (Oncorhynchus keta) and Chinook salmon (Oncorhynchus tshawytscha) in the Wood River system, Alaska

et al. 2011

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Small populations can provide insights into ecological and evolutionary aspects of species distributions over space and time. In the Wood River system in Alaska, USA, small aggregates of Chinook (Oncorhynchus tshawytscha) and chum salmon (O. keta) spawn in an area dominated by sockeye salmon (O. nerka). Our objective was to determine whether these Chinook and chum salmon are reproductively isolated, self-sustaining populations, population sinks that produce returning adults but receive immigration, or strays from other systems that do not produce returning adults. DNA samples collected from adult chum salmon from 16 streams and Chinook salmon from four streams in the Wood River system over 3 years were compared to samples from large populations in the nearby Nushagak River system, a likely source of strays. For both species, microsatellite markers indicated no significant genetic differentiation between the two systems. Simulations of microsatellite data in a large source and a smaller sink population suggested that considerable immigration would be required to counteract the diverging effects of genetic drift and produce genetic distances as small as those observed, considering the small census sizes of the two species in the Wood River system. Thus, the Wood River system likely receives substantial immigration from neighbouring watersheds, such as the Nushagak River system, which supports highly productive runs. Although no data on population productivity in the Wood River system exist, our results suggest source-sink dynamics for the two species, a finding relevant to other systems where salmonid population sizes are limited by habitat factors.

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Observer Accuracy and Precision in Aerial and Foot Survey Counts of Pink Salmon in a Southeast Alaska Stream

Cited by 28 publications

References 10 publications

Estimation and correction of seed recovery bias from moist‐soil cores

Estimation and correction of seed recovery bias from moist‐soil cores

The roles of extrinsic and intrinsic factors in the freshwater life‐history dynamics of a migratory salmonid

Self-sustaining populations, population sinks or aggregates of strays: chum (Oncorhynchus keta) and Chinook salmon (Oncorhynchus tshawytscha) in the Wood River system, Alaska

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