最新刊期
期 0 ， 2020
- 摘要：The otoliths from 3789 individuals, taken monthly from the Chekiang coast, during the period from September 1958 to December 1959 inclusive, were used in the present investigation. Monthly observation on the marginal structure of the otoliths and terminal index of ,each ring group carried out over a period of one year confirmed that the rings on the otolith were formed annually (excluding the first ring of the autumn spawners), as there was an complete turning over of one sort margin to the other during a definite period of the year. It is therefore concluded that the otolith of the Large Yellow Croaker is a reliable index for age determination. The opaque zone at the margin began to appear in January. Its percentage occurrance was highest in May and June, and fell to zero in July. However, the period of commencement of formation of the opaque zone varied regularly according to the age of the fish. It began to appear in April in the individuals with 1-13 rings, in February and March in those with 14-17 rings, and as early as in January in those with 18 rings onward. A preliminary analysis of the monthly length frequency distribution of the young fish and of the marginal structure of the otoliths revealed that the first annual ring on the otoliths of the young fish of the spring spawners was formed one year after and that of the young fish of the autumn spawners a year and a half after being laid. During the winter and spring the growth of the otolith was very slow, but during the summer and autumn it showed remarkable growth. It can be deduced that the growth rate of the present species also varies periodically, i.e. it grows slowly in the earlier half of the year, and remarkably in the latter half of the year. In the present report, the distinction between the true annulus and the false annulus has also been described.关键词：otoliths;age determination;Pseudosciaena crocea
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发布时间：2023-04-28 - 摘要：The aim of the present investigation is to study the feeding habit and seasonal variation of the food contents of the Large Yellow Croaker. Altogether 1,767 stomachs of the adult specimens, 20-52.5 cm in standard length, collected off Chekiang and Kiangsu in 1958 to 1961 have been studied. The results are as follows: The Large Yellow Croaker is a predatory fish with a more mixed diet. It takes nearly hundred species of animals, mainly small fishes (including young fishes), shrimps, mantis shrimps and crabs, of which the following 20 species of fishes (with *) and crustaceans are of great importance, namely, Harpodon nehereus*, Squilla oratoria, Harengula nymphaea*, Johnius belengerii*，Pseudosciaena polyactis*，P. crocea* (young fish) , Acetes chinensis, Leptochela gracilis, Solenocera sinensis, Parapenaeopsis hardwickii, Coilia ectenes*, C. mystus*, Collichthys niveatus*，C. lucidus*，Chaeturichthys hexanema*, Myctophum pterotum*, Xenophthalmus pinnotheroides, Squilla inornata, and Palaemon (Palaemon) gravieri. The majority of these animals are widely distributed and found abundantly in the area where the specimens were collected. The advantages of its feeding habit and of the abundant food supply seem favourable to the increase and stability of the population of the fish. However, its predacious nature should have direct inf1uence upon the population of the young fishes of several important species. The feeding intensity of this fish reaches its peak in the autumn and is very low during the spawning seasons, and it stil1 takes much food during the winter. However, the feeding intensity is rather even all the year around, as compared with some northern species of food fishes. [19, 21] Based upon the seasonal variation of the feeding intensity, the annual feeding cycle may be divided into two main phases: low feeding intensity during the spawning seasons, and high feeding intensity during the rest of the year. According to the period of appearance, the food contents can be divided into three categories: 1) those taken constantly, 2) those taken intermittently, and 3) those taken incidentally. The food contents are subject to great seasonal variations, and there occur two periods of maximum change in the composition of diet, one in spring and other in autumn. Further more, the items of food are greatly enlarged during the summer and autumn, while the size of food organisms is larger in winter and spring. Such seasonal changes indicate that the relationship between the need and availabi1ity of the food is rather complicated. According to the data on growth [12] of this fish, the growth rate in the summer is equal to that in the autumn or even higher. The results of food analysis, however, show that the feeding intensity is higher in the autumn than in the summer, as the index of fullness (21.3?) in the summer is only about one third of that in the autumn. It is interesting to note that the stomach contents in the summer season consisted mainly of the young fishes of Sciaenidae (30% in weight), while those in the autumn mainly the animals of poor quality such as Harpodon nehereus and Squilla oratoria (35.3 % in weight). Therefore, the relation between the quality of the food and the seasonal growth of the fish is obvious.关键词：the Large Yellow Croaker;feeding habit;SEASONAL VARIATION
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发布时间：2023-04-28 - 摘要：The important morphological characters of different stages of the eggs and larvae from fertilization to about 15 mm in total length have been described, based mainly upon the material obtained by plankton nets and by artificial fertilization made during the spawning seasons of the fish at Taichu-Yang, Chekiang, and near Naochow Island,Kwangtung in 1958 and 1959. It is interesting to note that the diameter of the eggs of the Taichu-Yang specimens (1.19-1.52 mm) is much larger than that of the Naochow specimens (1.09-1.32 mm). Some preliminary experiments on the development of the eggs under different constant temperatures (15℃，18℃, 20℃, 21℃, 23℃ and 25℃) were carried out in May and June 1959 at Taichu-Yang. The results showed that the eggs developed normally between 18-23℃. The eggs and larvae of the Large Yellow Croaker look very similar to those of the Small Yellow Croaker, Pseudosciaena polyactis Bleeker, and of some other sciaenids.Hence, their diagnostic features for distinguishing them have been described, especially the two species mentioned above.
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发布时间：2023-04-28 - 摘要：The material for this study was collected from Wenchow, Chekiang, during the period from March 18th to April 3rd，1961, just before the spawning migration of the fish.
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发布时间：2023-04-28 - 摘要：The present paper deals principally with the dynamics and difference of individual fecundity in the spring and autumn spawners of Large Yellow Croaker, collected in the periods from March-June and September-一October， 1959 from Taichu-Yang, Chekiang. 1n 304 spring spawners studied, the individua1 absolute fecundity ranges from 52.2 to1616.8 (× 1,000) (average 376.2); the individua1 relative fecundity r/q ranges from276.7 to 1005.9 (×1) (average 608.7) and r/1 from 2.1 to 32.7 (× 1,000) (average9.9). 1n 41 autumn spawners studied, the individual absolute fecundity ranges from156.1 to 601.2 (× 1,000) (average 286.8); the individua1 relative fecundity r/q from304.3 to 726.6 (×1) (average 459.5) and r/1 from 4.5 to 14.1 (× 1,000) (average 7.8). After analysing the relations of individual fecundity to weight (excluding the gut and the gonads) ， standard 1ength and age of this fish, we consider that: 1, The individual fecundity increases, but differently, with the increase of weight, length and age.2, 1t is closely associated with weight rather than with length and age. Therefore the main influential factor is growth.
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发布时间：2023-04-28 - 摘要：The present paper deals with the variation of meristic and measurement characters in 7 principal spawning shoals of the Large Yellow Croaker along the coast of China. The problem of classification of its geographical populations is also discussed. Analyses of our samples yeilded the following results: 1. Both the average and the frequency distribution of the meristic characters, such as the gil1-rakers and branches of the air-bladder, and of the measurement characters such as eye-diameter, the depth of the caudal peduncle, the body depth, etc., increase or decrease gradually from the north to the south according to the distribution of the populations. It is worth mentioning that individuals with 27 vertebrae were met with in the three main shoals off Kiangsu and Chekiang belonging to the northern area of distribution, but not in the southern ones. 2. Basing upon the comparative analyses of Mdiff and frequency distribution of some characters, together with the data on oceanographical conditions, peculiarities of reproduction, and the structure of the populations, we further classify the Large Yellow Croaker along the coast of China into three geographical populations--the Tai-chu race, the Min-Uehtung race and the Naochow race. Among these three races the difference between Tai-chu and Naochow races is very conspicuous, while the Min-Uehtung race has a transitional disposition. 3. The relationships between morphological characters of the populations and some environmental factors are also preliminarily discussed.关键词：Large Yellow Croaker;geographical populations;meristic and measurement character
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发布时间：2023-04-28 - 摘要：This article is the analytic results of the data on population structure of the Large Yellow Croaker, collected along the China coast from 1958 to 1960. It is our first attempt to analyse the problem of geographical variation of its population pecularities such as life-span, age-composition and sexual maturation.关键词：Large Yellow Croaker;geographical variation;population structure
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发布时间：2023-04-28
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