Precision and accuracy of Dahl‐Lea back‐calculated smolt lengths from adult scales of Atlantic salmon<i>Salmo salar</i>

Hanson, Nora; Smith, Gordon W.; Middlemas, Stuart J.; Todd, Christopher

doi:10.1111/jfb.13863

Cited by 12 publications

(9 citation statements)

References 17 publications

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“…Scale reading methods followed international guidelines on age and growth determination in salmon ( 67 , 68 ). Studies on marked and recaptured fish have found good correspondence between the period spent at sea versus sea age inferred using scale reading ( 66 ) and size at first capture versus back-calculated size ( 69 , 70 ).…”

Section: Methodsmentioning

confidence: 99%

Introgression from farmed escapees affects the full life cycle of wild Atlantic salmon

et al. 2021

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Section: Methodsmentioning

confidence: 99%

Introgression from farmed escapees affects the full life cycle of wild Atlantic salmon

et al. 2021

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“…The present data are for stratified subsamples ( n = 1947; 96–114 fish per year) spanning the full available date range of 1SW return migrants captured within each year (typically April/May to end August). Fish were measured (fork length, rounded down to 0.5 cm) and weighed (to 0.01 kg), and scale samples removed from the standard region (Hanson et al ., 2019; Shearer, 1992). Scales were air‐dried in paper packets and stored for further analysis.…”

Section: Methodsmentioning

confidence: 99%

“…An estimate of the body length of each fish at the midpoint of the winter annulus was derived by back‐calculation of scale measures, and by applying the correction factor of Hanson et al . (2019) to the estimate of body length of the smolt at river emigration. Growth in body length between smolt emigration and capture of the measured adult fish was assumed to be isometric with the scale radius.…”

Section: Methodsmentioning

confidence: 99%

Variation in the post‐smolt growth pattern of wild one sea‐winter salmon (Salmo salar L.), and its linkage to surface warming in the eastern North Atlantic Ocean

Todd

Hanson

Boehme

et al. 2020

Journal of Fish Biology

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Variation in circulus spacing on the scales of wild Atlantic salmon is indicative of changes in body length growth rate. We analyzed scale circulus spacing during the post‐smolt growth period for adult one sea‐winter salmon (n = 1947) returning to Scotland over the period 1993–2011. The growth pattern of the scales was subjectively and visually categorized according to the occurrence and zonal sequence of three intercirculus spacing criteria (“Slow”, “Fast” and “Check” zones). We applied hierarchical time‐series cluster analysis to the empirical circulus spacing data, followed by post hoc analysis of significant changes in growth patterns within the 20 identified clusters. Temporal changes in growth pattern frequencies showed significant correlation with sea surface temperature anomalies during the early months of the post‐smolt growth season and throughout the Norwegian Sea. Since the turn of the millennium, we observed (a) a marked decrease in the occurrence of continuous Fast growth; (b) increased frequencies of fish showing an extended period of initially Slow growth; and (c) the occurrence of obvious growth Checks or hiatuses. These changes in post‐smolt growth pattern were manifest also in decreases in the mean body length attained by the ocean midwinter, as sea surface temperatures have risen.

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“…Upon return, a proportion of the salmon is captured by anglers, who report size of each fish and often provide researchers with a scale sample ( 8 ). Experienced scale readers can reconstruct individual growth in length at different periods at sea by analyzing growth pattern in the scales ( 9 , 10 ). By using these data in combination with information on capture site and biological information about the species, it is possible to reconstruct spatiotemporal patterns in marine growth and thereby infer detailed information on the marine conditions while the fish was at sea.…”

Section: Introductionmentioning

confidence: 99%

Ecological regime shift in the Northeast Atlantic Ocean revealed from the unprecedented reduction in marine growth of Atlantic salmon

Vollset

Urdal²,

Utne

et al. 2022

Sci. Adv.

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Ecological regime shifts are abrupt changes in the structure and function of ecosystems that persist over time, but evidence of contemporary regime shifts are rare. Historical scale data from 52,384 individual wild Atlantic salmon caught in 180 rivers from 1989 to 2017 reveal that growth of Atlantic salmon across the Northeast Atlantic Ocean abruptly decreased following the year 2004. At the same time, the proportion of early maturing Atlantic salmon decreased. These changes occurred after a marked decrease in the extent of Arctic water in the Norwegian Sea, a subsequent warming of spring water temperature before Atlantic salmon entering the sea, and an approximately 50% reduction of zooplankton across large geographic areas of the Northeast Atlantic Ocean. A sudden decrease in growth was also observed among Atlantic mackerel in the Norwegian Sea. Our results point toward an ecosystem-scale regime shift in the Northeast Atlantic Ocean.

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Precision and accuracy of Dahl‐Lea back‐calculated smolt lengths from adult scales of Atlantic salmonSalmo salar

Cited by 12 publications

References 17 publications

Introgression from farmed escapees affects the full life cycle of wild Atlantic salmon

Introgression from farmed escapees affects the full life cycle of wild Atlantic salmon

Variation in the post‐smolt growth pattern of wild one sea‐winter salmon (Salmo salar L.), and its linkage to surface warming in the eastern North Atlantic Ocean

Ecological regime shift in the Northeast Atlantic Ocean revealed from the unprecedented reduction in marine growth of Atlantic salmon

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