CalCOFI Reports, Vol. 11, 1967 - California Cooperative Oceanic ...

48 CALIFORNIA COOPERATIVE OCEANIC FISHERIES IXVESTIGATIONSstages (or etap) from egg to adult, and upon theyearly cycle of life inclusive of spawning and shoalingcycles as suggested by Steven (1948). Even the sameenvironmental factors may have different effects upontwo individuals at different stages or cycles. From theabove discussion it may be readily accepted that thesystematic fractions must be distinguished by differenceof occurrence of the developmental stages andthe maturation phases.For these reasons, the biological information mustbe systematized on the basis of developmental stagesand yearly cycles for each species. The system obtainedas such may provide hypotheses of the systematicstructure and assessment of any fish populations.Accordingly the present section is divided into threeparts : (i) biological notes of the fish at each developmentalstage or maturation phase, (ii) systematicfractions, and (iii) assessment of the population.The developmental stages and yearly cycle of lifeare to be defined through the whole body of knowledge,and will be modified if those categories are found tocontradict observations made by succeeding investigations.At present, we can assume that the anchovypasses through the developmental stages defined byHubbs (1943), and that two yearly cycles repeatedlyappear every year at the adult stage. The developmentalstages and yearly cycles adopted here are listedbelow. The substance of the stage or cycle was obtainedby unifying existing knowledge on all aspects of thestage or phase in question.Developmental stage I Yearly cycle of life- - - .Juvenile 6efore reaching adult form) _ ___________ I --Geographical DistributioltThe Japanese anchovy is actually widely distributedin the temperate zone of the Far East, extendingfrom southern Sakhaline to Formosa, but the fisherieson this species have been concentrated in the watersaround Japan and Korea (Hayasi 1961). Almost allthe coastal waters surrounding Japan produce thisspecies, except south of the Kurosio Current (Matsubara1955, Hayasi 1961). Most previous descriptionsare given only in terms of the species.Egg and larval stages. The spawning activities ofanchovies have been determined through systematicplankton net collections conducted since 1949 (Nakaiet al. 1955, Yokota and Asami 1956, Yamanaka andIto 1957, Ex. Com., Conf., Invest. Neritic-PelagicFisher. Japan 1961-63). According to these studies,the species actually spawns over a wide extent of thewaters between Hokkaido and Kyusyu, from the inletsto the high seas to a distance of around 1,000 nauticalmiles from the coast. The spawning activities aredistributed more abundantly over the middle andsouthern Pacific coast of Japan, and around the edgeof continental shelf than in any other part of the sea.The spawning season lasts throughout a year in southof the middle Pacific and west Japan sea regions. Theheaviest spawning activities occur during winter andearly spring in the southern areas around Kyusyuand Sikoku, or in spring and in autumn in centralPacific waters such as between the Kii and BosoPeninsulas. Within an area the spawning proceedswith the passage of time from the outer coastal watersto the bays and inlets (Hayasi 1961; Asami 1958a,1958b, 1962). The eggs are often transported bycurrents, and then the distribution pattern changesdepending upon age of the eggs (Yokota 1953). Theanchovy larvae have the same distribution as theeggs (Nakai et al. 1955, Yokota and Asami 1956,Yamanaka and It0 1957).Postlarval and juvenile stages. It is dificult toestimate, with the use of plankton nets, distributionand abundance of the postlarvae and juveniles thathave gained enough swimming activity to avoid thenets. Some of the postlarval stocks are concentratedin the coastal waters, and are exploited by boat seinesand other commercial fisheries operating within 5miles from the coast and 20 m from the surface. Themajor fishing grounds for postlarval anchovies arelocated within the general areas comprising thespawning grounds. Representative fishing groundsare : The coast of Ensyu Nada and Hyuga Nada on thePacific, and various parts of the Set0 Inland Sea.Minor fishing grounds for postlarvae are found on thecoast south of Kasima Nada on the Pacific and inToyama Bay on the Japan Sea (Hayasi 1961). Thepostlarvae are abundantly distributed out of the fishinggrounds (Nakai et al. 1962). Dense shoals areoften found on siome in the waters off eastern coast ofHonsyu (Odate 1957). The juveniles, less lucrativethan the postlarvae, are caught just after the majorfishing season for sirasu (Tanaka 1956).Immature stage. Anchovies leave the nurserygrounds by the time they reach the immature stage,and some are exploited by commercial fisheries mainlyin the bays and inlets (Ex. Com., Conf. Invest.Neritic-Pelagic Fisher. Japan 1961-63, Hayasi 1961,Asami 1962, Takao 1964).Adult stage. The adult anchovy is exploited in allareas. Generally speaking, the ratio of the adultsamong the total anchovy catch is higher in the outercoastal waters than in the bays and inlets, and ishigher in the northern area than in the south (Yamanakaand Ito 1957, Hayasi 1961).a. Xhoaling cycle. Almost all the anchovies caughtin the areas south of middle Pacific region are in theshoaling cycle (Hayasi 1961, Usami and Sugiyama1962).b. Spawning cycle. The spawning areas are identicalwith the distribution areas of the spawningadults. The set nets in the northern areas catch the