Investigation of age composition and growth of cod Gadus morhua morhua of the Barents Sea in connection with the estimation of its stocks state

Kotenev, B. N.; Kuznetsova, E. N.; Bondarenko, Marina

doi:10.1134/s0032945209010068

Cited by 3 publications

(1 citation statement)

References 2 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Intense fishing may be considered as an additional selection factor which gives selective advantage to quickly maturing individuals (Borisov, 1978;Naish & Hard, 2008;Enberg et al, 2012). Furthermore, thinningout of population can lead to increase in the food provision, which in turn can cause increase in the growth rate and earlier maturation (Nikol'skij, 1974;Kotenev et al, 2009). Thus, increase in the maturation rate in the conditions of relative stability of the food base of fish in general indicates deterioration of the status of the grayling population in the upper reaches of the Vym River.…”

Section: Discussionmentioning

confidence: 99%

Change in the state of an exploited fish population: From individual indicators to integral assessment

2020

View full text Add to dashboard Cite

We adapted the approach used for the integral assessment of the status of ecosystems in order to assess population status. Classic theoretical concepts of fish population dynamics are the basis of this approach. The convolution of information about changes in several structural and functional characteristics into one integral index was performed using the analytical function of desirability. The index varied 0 to 1 and quantitatively characterizes the state of the population. This approach was tested on the example of the European grayling Thymallus thymallus (Linnaeus, 1758), inhabiting the Vym River (basin of the Northern Dvina River, North of the European part of Russia). The materials were collected during the environmental monitoring carried out by the Institute of Biology of Komi Science Centre of the Ural Branch of the Russian Academy of Sciences (IB FRC Komi SC UB RAS) in 2002, 2005–2019. The population parameters used in the calculations (relative abundance; average and maximum age of fish; the proportion of matured individuals in the 4+ age group; average specific growth rate of fish at the age of 6+; body weight of fish in the age group 6+) were characterized on the basis of the control net catches. Compared with the period 2005–2006, the value of the integral index in 2015–2018 decreased by almost two times. This indicates deterioration in the condition of the grayling group in the study area. There were no serious disturbances in the fish habitat in this area. The main hydrochemical and hydrobiological indicators have not changed significantly. The main reason for the observed changes is likely the significant increase in the impact of recreational anglers. The proposed integral index may be useful both for assessing the state of fish populations and for developing measures for the rational management of fish stocks.

show abstract

Section: Discussionmentioning

confidence: 99%