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

REPORTS VOLUME XI, 1 JULY 1963 TO 30 JUNE 196641SERIES 11042.43 CLASS 1941-42 CLASSsoAPR. 1044I& SERIES 28jAN.1946wn m so . w8 A-xJ real946z8300 &80 APR. 1046JULY 194680 AUG. 1046other Australian states gave results which were lessreliable, but on the whole consistent with the findingsfor Victoria.REP ROD U CTI 0 NGonad maturity stages of E. australis were describedby Blackburn (1950 a). The running ripestage was not found, so estimates of length at firstmaturity were based on frequency of occurrence of“full”, “spent”, and “recovering” gonads in fishof successive length-groups. This showed that virtuallyall fish of both sexes become sexually mature at oneyear of age (about 6 em) in Victoria. Data from Tasmaniawere consistent with this result, and those fromother states were too scanty to justify a conclusion.Spawning seasons and areas were identified bystudying the distribution of advanced gonad stagesin samples of fish old enough to be mature, and thedistribution of eggs and larvae in plankton catches.The results (Blackburn 1941, 1950 a; Kott 1955)may be summarized as follows.Xozctherrz subspecies.-Spawning occurs from Octoberthrough April with a peak in summer, mostly inbays and estuaries and to a much less extent in opensea waters over the continental shelf.Easterrz subspecies.-The data are not nearly asgood as for the southern subspecies. The peak spawningseason in the southernmost part of the range is thesummer, like that for the adjacent southern subspecies,but it appears to become progressively earlier,through spring and probably into late winter, in successivelymore northern areas. In the southern part ofthe range there is some spawning both in inlets and inthe open sea, as with the southern subspecies; it isdifficult to say which of these habitats is the moreimportant for spawning in that region, but farthernorth, especially in Queensland, the inlets appear to bequite unimportant as spawning places compared withthe sea.Western. subspecies.-The information is veryscanty; all of it concerns gonad stages in inlet fishfrom the southern end of the range, and points to asummer peak of spawning.80 SEW. 1946eo 100 lllMOY LENGTH IN UW.FIGURE 11. Length frequency polygons by months, two series for E.australis from Port Phillip Boy, Victoria. All samples in series 1 arefrom the head of the bay; in series 2 the January and Februaryfish, and those from the younger age-group in later months, are fromthe head of the bay, and the others are from localities closer to thesea (from Blackburn 1950a).length subsequent to “ring” formation on the scales.They also agree with length frequency data fromPort Phillip, which are mainly for fish under threeyears of age, and some of which are shown in Figure11 (Blackburn 1950 a). Figure 11 shows that mostgrowth occurs in spring and summer, and none inwinter. Scales read from anchovies obtained fromCHANGES IN DISTRIBUTION WITH AGEAND SEASONThe following observations (Blackburn 1950 a,1957) have been made on the southern subspecies, forwhich the best data on occurrence, growth, and reproductionare available.1. In Port Phillip, anchovies under two years ofage are most common at the head of the bay andolder fish are most common closer to its mouth (e.g.,Figure 11). No similarly detailed studies of distributionof age-groups were made in any other bays orestuaries.2. Along the Victorian and Tasmanian coasts, anchoviesof various sizes, but mainly large enough to betwo and a half years or older, occur in the sea outsidethe inlets in the winter months. They are much less