Age and length-weight structure of local stocks of sockeye salmon <i>Oncorhynchus nerka</i> in some feeding-spawning lakes of Kamchatka Region

Abstract

Age and length-weight structure of sockeye salmon spawners are considered for the feeding-spawning lakes of southeastern Kamchatka, as Dalneye (1976-2013), Blizhneye (1939-2013), and Listvenichnoye (1999-2013), and for Lake Sarannoye on Bering Island (1990-2013). By these data, the age of sockeye salmon maturing is: 2.2, 2.3 and 3.2 in Lake Dalneye, 1.2, 1.3, 2.1 and 2.2 in Lake Blizheye, 2.2, 2.3 and 3.3 in Lake Listvenichnoye, and 2.2, 2.3, 3.2 and 3.3 in Lake Sarannoye. These age groups dominate in the samples of spawning sockeye with the portion 70-90 %. Long-term dynamics of length and weight of sockeye spawners is distinguished by negative trends significant for the longest time-series in Lake Blizhneye and insignificant for the shorter one in Lakes Dalneye; the length of observations in Lakes Listvenichnoye and Sarannoye is not enough to reveal trends. Besides, cyclic variations with the period 5-10 years could be revealed for the long tome-series. As a rule, each cycle includes the phases of gradual decreasing and sharp increasing of length and weight. Year-to-year dynamics of the length-weight structure in the common period of observations is similar for all investigated lakes.

Genetic Structuring and Conservation of Asian Sockeye Salmon: Identification of Regional Stock Complexes

“…For instance, the length of the rivers on the west coast significantly exceeds that of the rivers of North-East Kamchatka. The lower and middle sections of the channels of most West Kamchatka rivers pass through low-lying swampy tundra and have a weak current (Pogodaev, 2013). In the majority of these watersheds, there are no deep lakes essential for the reproduction of this species, except for the Ozernaya and Palana rivers.…”

“…Juvenile salmon from this region first migrate to partially enclosed coastal waters, bays, and inlets before running to the open sea. This transitional phase may significantly influence their early marine survival (Pogodaev, 2013). Rivers on the northeast coast tend to be shorter and faster flowing.…”

“…Positive bottleneck tests have been obtained for almost all samples from the Kamchatka River watershed including Azabachye sample (Table 1, Supplementary Table S3). In summary, we can deduce that the genetic characteristics unique to the metapopulation of Kamchatka river basin were caused by prolonged isolation of its part during the Upper Pleistocene glaciations within a large lake that existed in the middle reaches of the river (Bugaev & Kirichenko, 2008), subsequent rapid expansion into local and neighboring watersheds during the Holocene transgression, and, probably, secondary contact with adventive populations that colonized predominantly the lower part of the river basin after the glacier retreat (Brykov et al, 2005;Khrustaleva et al, 2020).…”

Adaptive and Neutral Polymorphisms of the Onne-DAB Gene from the Major Histocompatibility Complex (MHC) in Sockeye Salmon Populations on the Asian Range

“…The shift in genotype frequencies in the sample indicates either a relatively recent epizootic in this lake-river system or the limited species composition of pathogens and parasites in this water body. There is only fragmentary information about the planktonic community of Anana Lagoon Lake [59]. The composition of zooplankton is very specific here: the abundance of Cyclops scutifer is low, and the main food organism for juvenile sockeye salmon is the brackish-water cold-tempered species Limnocalanus macrurus, which is not an intermediate host for Diphyllobothriidae.…”

“…Therefore, it can be assumed that in this lake, the infestation of fish with cestode plerocercoids should be low, and other parasitic organisms should come to the fore. According to the data of Bugaev and Kirichenko [60], the density of oligochaetes in benthos samples was quite high, which may indicate the presence of myxosporidia in the lake because their actinosporeic phase takes place in the bodies of Oligochaeta of the family Tubificidae [52]. On the other hand, similar effects in natural populations can be explained by demographic processes associated with a high degree of isolation of the lacustrine sockeye and a decrease in the effective population size (genetic drift, bottleneck).…”