Половое созревание минтая в северной части Охотского моря и обоснование минимального промыслового размера

• Main Authors: Фадеев, Н., Раклистова, М.
• Format: Text
• Language: unknown
• Published: Федеральное государственное унитарное предприятие «Тихоокеанский научно-исследовательский рыбохозяйственный центр» 2003
• Subjects: Okhotsk; Kamchatka; okhotsk sea; КАМЧАТК*
• Online Access: http://cyberleninka.ru/article/n/polovoe-sozrevanie-mintaya-v-severnoy-chasti-ohotskogo-morya-i-obosnovanie-minimalnogo-promyslovogo-razmera; http://cyberleninka.ru/article_covers/212187.png

Изучена динамика полового созревания минтая в зависимости от длины и возраста в двух центрах воспроизводства в Охотском море у западной Камчатки и в североцентральной части моря за 19841988 гг. Выявлена половая, межгодовая и географическая изменчивость темпов полового созревания. На основе динамики биомассы поколения с возрастом и скорости созревания предложено увеличить минимальный промысловый размер (МПР) до 37 см вместо 32 см в Правилах рыболовства. При этом предлагается увеличить прилов минтая менее 37 см до 1620 % (в Правилах 8 %) в зависимости от численности пополнения и общего состояния запасов. Вылов неполовозрелого минтая при внедрении рекомендуемых изменений уменьшится в 1,5 раза по сравнению с ограничениями в действующих Правилах рыболовства. Но при этом существенно увеличится средняя масса минтая, доля самок в уловах, а следовательно, выход икры и филе. Change of a ratio of mature and immature individuals with increase of length and age is one of the major population signs of fishes. The data on maturity are mentioned when stocks estimation and possible catch forecasting. The same parameter is taken into account for determination of the minimal size of fish, allowed to catch, that is considered as a basis of rational fishery management. For walleye pollack, the minimal commercial size must have the value that allows reducing the catch of immature fish with low weight to the minimal level in this case a basis of the catch would be formed by repeatedly spawning individuals. Herein the data on maturity of the pollack spawning at western Kamchatka and in the north-central part of the Okhotsk Sea (i.e. at two the largest spawning grounds of the Okhotsk Sea) are analyzed, obtained in 15 and 9 years, accordingly. Percentage of mature individuals in each size class was taken as a criterion of maturity. Age was calculated by the length-age keys. Sexual dimorphism and interannual and geographical variability were analyzed in detail for every ten-day period and then averaged for the whole periods, with usage of leveling by logistical function. Generally, immature males in both areas included the individuals with the length up to 50 cm, females up to 53 cm. A half of males was completely matured at length of 3536 cm, females 3739 cm. In certain years, the size of sexual maturity of males changed from 40 to 51 cm, females from 39 to 54 cm. Females became completely mature, as a rule, at 24 cm longer length than males. Interannual variability of maturity-length correspondence was well expressed in both areas. The rate of males and females maturation was higher in 19941997 and lower in 1987, 19911993 and 1998. The pollack spawning in the northern Okhotsk Sea reached its sexual maturity at smaller length in compare with that one from western Kamchatka. The difference was expressed well enough for both sexes, although didn't exceed 12 cm. The 50: 50 ratio of mature and immature fish was chosen as the criterion for determination of the minimal commercial size. Using this criterion, the minimal commercial size for the pollack in the northern part of the Okhotsk Sea was estimated as 37 cm in average (it is 32 cm in present rules of fisheries). For more detailed determination, the biomass dynamics with age has to be studied taking into account a natural mortality rate. Usually, the biomass of a generation of pollack is maximal in the age of 6 years. If to assume, that the age of rational exploitation beginning is to precede the age of the maximal biomass, the withdrawal would begin in the age 5 years, with size 36.3 cm. So, if the minimal commercial size for the northern Okhotsk Sea pollack will be 37 cm, a part of the population with the size