Abstract
Two groups of juvenile sockeye salmon are feeding in Lake Azabachye. They belong to the 2nd order stock of the lake (stock A) and to other 2nd order stocks of middle and down stream tributaries of the Kamchatka River which underyearlings migrate into the lake for feeding and wintering (group E). The main part of the stock A leaves the lake to the sea at the age 2+ (mainly 2.3) and the youngsters of the group E migrate to the sea at the age 1+ (mainly 1.3). The body length and weight parameters of the stock A smolts at the age 2+ and the group E smolts at the age 1+ could be similar or dissimilar in particular years. The maximal difference between the smots of these stocks is observed in the years with higher body length and weight for the stock A. Mean for 1979–2016 length and weight of smolts at abovementioned ages are evaluated as 98.42/87.46 mm and 10.40/7.38 g for the A/E stocks. For the stock A, statistically signifcant positive correlation is noted between size-weight parameters of smolts in the years of emigration and their abundance in the years of mass return. However, the regression has a shift between the periods of emigration/return of 1979–2000/1982–2003 and 2003–2013/2006–2016. The correlation is higher for the frst period (r = 0.820; P < 0.001 for body weight and r = 0.797; P < 0.001 for body length, n = 16) than for the second one with higher abundance (r = 0.669; P < 0.05 for body weight and r = 0.711; P < 0.05 for body length, n = 11). On opposite, the returns of the group E depend weakly on size-weight parameters of its smolts for the period of emigration/return of 1979–1997/1982–2000 (no data for return in 1999) and the dependence is insignifcant for the period of 2000–2013/2003–2016.
Highlights
Two groups of juvenile sockeye salmon are feeding in Lake Azabachye
They belong to the 2nd order stock of the lake and to other 2nd order stocks of middle and down stream tributaries of the Kamchatka River which underyearlings migrate into the lake for feeding and wintering
The main part of the stock of the lake (stock A) leaves the lake to the sea at the age 2+ and the youngsters of the group E migrate to the sea at the age 1+
Summary
Полученные результаты свидетельствуют о более сильном влиянии размерно-массовых характеристик смолтов стада «А» и группировки «Е» на численность возвратов половозрелых рыб этой же группировки в период 1982–2000 гг. Азабачьем нагуливаются две группы молоди (Бугаев, 1995, 2011; и др.): аборигенная молодь стада нерки оз. Увеличение размерно-массовых характеристик смолтов нерки стада «А» положительно влияло на возвраты половозрелых рыб этого аборигенного стада; применительно к рыбам транзитной группировки «Е» отмеченные выше связи были менее заметны (Бугаев, 2004а, 2011; Бугаев и др., 2004, 2007). Вулканическим пеплом вулкана Шивелуч, когда на бассейн озера выпало 15–18 мм пепла (Бугаев, Базаркина, 2013), был резон вернуться к обозначенной проблеме только после завершения серии возвратов основной возрастной группы нерки стада «А» возраста 2.3 (средняя встречаемость в пробах — 70 %), что и произошло в 2016 г. Цель настоящей работы — выяснить, как возвраты половозрелой нерки стада «А» и группировки «Е» в 1982–2016 гг. были связаны с размерно-массовыми характеристиками смолтов соответствующих 1979–2013 гг. ската
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