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

REPORTS YOLUME SI, 1 JULY 1963 TO 30 JUNE 1966 11California including northern Baja California. Followupcruises in southern and central California serveas both gear research cruises and intensive samplingsurveys.The first phase of the expanded survey, in fiscal1965-66, was designed to provide continuity withcruises conducted during the past and to develop thefollowing survey techniques, which have been in effectsince June, 1966. An echo sounder is operated continuouslyduring the day over predetermined transectlines that extend perpendicularly from shore for atleast 35 miles or until the 1000-fathom depth contouris reached. These lines are spaced 15-30 miles apartand average about 50 miles in length. Hourly fixes areobtained and the number of schools appearing on theecho sounder are recorded for each hour of runningtimci. Identification of species is accomplished by echotrace characteristics and by fishing x small, 30-footmidwater trawl. The trawl is also fished at regularIO-miles intervals during the night as the vessel returnsinshore over the outbound transect lines. Arecord is kept of all visually observed surface schoolsand indications of fish during both day and night.Catch records include species, numbers, sizes and sex.Scale or otolith samples are obtained Prom the imtantspecies for determining age composition. Limitedoceanographic obserrations pertaining to fish distributionare regularly obtained. These include bathytherinographcasts, water turbidities, temperatures, aiidweatlier conditions.We hare now completed five cruises of this newtype ; two to central California. two off southern Californiawhich includes northern Baja California andone in southern Baja California. Anchovies have beentlie dominant species in all areas. Since these surveyswere initiated some important seasoiial distribution andbeharioral aspects have been deterniined for anchovies.During spring the anchovy population was composedof thousands of rery sniall schools distributed overlarge areas extending at least 50 to 80 miles offshore.These schools were located near the surface in clear,deep water and normally contained less than 2 tons offish. All were adults in advanced spawning stages.Imge compact schools, suitable for purse-seine fishing,were scarce and found only in a, few localized areas.*Juvenile fish were generally found close to shore inwater shallower than 50 fathoms. During sumnier andfall all sizes of anchovies were found rniich closer toshore, at greater depths, and in larger but fewerschools. Decrease? in school numbers from spring tofill1 in th(J southern California area exreedd 80 percent.These rcsults indicate that, in general. the fishspread over a large area in spring to spawn and concentratein small coastal areas during suninier and fall.The most opportune time to estimate population sizeappears to be spring. With the large iiuinber of schoolsand extensive distribution, echo sounding surveyingis much inore effective. Schools size and identificationare also inore easily detemniined. Fall aiid suninier distributions,with fewer and large schools, decrease theeffectiveness of tlie echo sounder in probability of de-tection, species identification and school size determination.This type of distribution and behavior shouldbe more favorable for commercial fishing.School types and behavior patterns were also observed.Small numbers of horizontal-layer schooltypes 80 to 100 fathoms below the surface and morenumerous plumes located 20-50 fathoms deep werethe predominant schools in northern Baja Californiaand central California. The southern California regioncontained these types plus plume-type schools at shallowerdepths. At nightfall a11 school types came tothe surface where almost all dispersed into surfacescatter or loose detached school segments. Only a veryfew remained compact enough to be visible as a bioluminiscentspot or register as an echo trace.The night behavior of anchovies appears closely associatedwith the upper extremity of the scatteringlaper that coiners toward the surface after dark. Theafter dark rise and surface dispersal of schools suggestsa feeding behavior as eyidenced by the largenumbers of recently ingested food organisms observedin stomachs of night-caught fish. 9 very high percentageof these organisms were euphausiids, which are animportant constituent of the upper scattering layer.Quantities of sardines were present only in thesouthern part of Sebastian Vizcaino Bay. Adults ofthe fall spawning sub-population overwhelmingly predominatedthe samples taken. This group is now apparentlythe strongest remnant of the whole population.Incoming juvenile year-classes were practicallynil. Other species surveyed were minor in importancecompared to anchovies. Juyenile jack mackerel,mostly of the 1966 year-class, were widely distributedin small scattcred schools. Trawl catches usuallyranged from 1 to 50 individuals, they rarely exceededI00 specimens.Hale were locally abundant in July off San Francisco.Many- schools were found associated with whitebaitsmelt. Both species were in close association witheach other, the hake wre 1 to 3 fathoms off the bottomwith the smelt 3-4 fathoms abovc them. The hakeappeared as small groups, 20 to 50 yards apart. Aseries of these groups was counted as a school. Onesuch school was over a mile across. Those sampledwere large adults, 20-25 inches. Only minor traces ofhake were noted in southern California in Octoberand no concentrations were seen in November off centralCalifornia.The Department continued to issue data reports onpast-year cruises (since 1930). The material is codedonto IKM carcls. organized into tables by ail electroniccomputer, and printed directly by a photographicprocess. The data are printed in the California CooperativeOceanic Fisheries Investigations ( CalCOFI)Data Report series.EicL.lit reports, co~~ring the I) years from 19330through 1938, wcre printed and distribixted whik twoinore reports 19 and 10) for 1939 and 1960 Twre conpletedniid ready for printing. Data for the sevraladditional yearc, were partially processed and will beprinted as they are ready.