No abstract

Total egg production in the “reference” points of canyons, date of peak spawning, duration of spawning and coefficients of egg losses are evaluated in this work on the data of ichthyoplankton survey math simulation for the canyons of Avacha Gulf for 2014–2018. It has been figured out that during the period analyzed, the spawning intensity of walleye pollock in the canyons decreased compared to the period 2003– 2013.

Distribution and biological parameters are considered for eggs and adults of two flatfish species on the data of annual surveys conducted on the shelf of southeastern Kamchatka in summer of 2011–2014 and 2016–2019. The eggs of Pleuronectes quadrituberculatus were sampled mostly at the stage of a germinal strip forming, whereas the eggs of Hippoglossoides elassodon were mostly at the stage of embryo cleavage. The main congestions of the eggs were found in the Kronotsky Bay and northern Avachinsky Bay. The adults of both species concentrated mainly in the northern Kronotsky Bay, at Cape Povorotny. Old age groups prevailed in aggregations of P. quadrituberculatus, but middle-age and young fish — in the aggregations of H. elassodon.

Purpose: To characterize some issues of East Kamchatka pollock reproduction in the last 10 years.Methods: complex (ichthyoplankton and hydrological) surveys in the Pacific waters adjacent to the Kamchatka Peninsula and the northern Kuril Islands, surveys in the spawning center —  the “North” canyon, located in Avacha Bay, layer-by-layer surveys in the canyons and on the shelf.Novelty: the currently available data on the main spawning areas of the Eastern Kamchatka pollock were supplemented, new data on the state of the spawning stock, vertical distribution of eggs at different stages of development were presented.Results: During the period under consideration, the main pollock spawning in Avacha and Kronotsky bays occurred above deep-water canyons, and on the shelf near southeastern Kamchatka and northern Kuril Islands —  in the whole surveyed water area, in some years —  to the south of the island Paramushir. According to the results of ichthyoplankton surveys, model calculations, the spawning stock of the Eastern Kamchatka pollock peaked in 2010, and then it gradually decreased. Currently, resources are at an average level. Horizons of the main pollock spawning in deep-water canyons change in an inter-a nnual aspect. In addition, as egg development, as a result of internal processes occurring in the canyons (internal waves), it, then rises, then falls in the underlying layers of water.Practical significance: The results of the work can be used to improve the method of assessment of the current and prospective state of stocks, justification of the TAC of the Eastern Kamchatka pollock.

В работе использованы данные, полученные в результате проведения ихтиопланктонной съемки в июне 2016 г. на Западно-Камчатском шельфе. Личинка наваги была поймана на глубине 63 м при температуре воды у дна +1,7 ºС и на поверхности +6,8 ºС в районе с координатами 53º19´ с. ш. и 155º37´ в. д. Полная длина личинки наваги составила 9,7 мм. Миомеров-58-59.