I

AGE AND GROWTH OF SKIPJACK TUNA, KATSUWONUS PELAMIS, AND YELLOWFIN TUNA, THUNNUS ALBACARES, AS INDICATED BY DAILY GROWTH INCREMENTS OF SAGITTAE

JAMESH. UCHIYAMA'AND PAUL~TRUHSAKER~

ABSTRACT

Counts of the daily growth increments on otoliths provided the means for establishing growth curves for central Pacific skipjadc tuna,Katsuwnuspelis, up to 3 years old and for central Pacific yellowfin tuna, Thunnus albacarea, up to 2 years old. The data indicated three stanzas of linear growth for 51 skipjack tuna ranging in size from 3 to 80 cm fork length. Estimated daily growth rates were 1.6 -/day for fish up to a length of about 27.0 an;0.8 mm/day for fish between 27.0and 71.4 cm; and 0.3 mmlday for fish between 71.4 and80.3 an.Growth data for 20 eastern Pacific skipjack tuna ranging in size from 38 to 65 cm fork length suggested that skipjack tuna in the eastern Pacific grew at a slower rate than those from the central Pacific. Age determinations of 14 central Pacific yellowfin tuna suggested possibly two stanzas of linear growth.Estimatedgrowthratesare1.4mm/dayforfishup toalengthof64.2cmand0.9mm/dayforfish between 64.2 and 93.0 cm. Growth curves from this study were compared with published growth curves based on other methods. The validity of daily growth increments was tentatively determined by observationson skipjack and yellowfin tunas held in captivity. Agreement of our growth curvea with those of previous studies on the same stock oftunas using other growth estimating techniques also suggests that our aging technique is acceptable. However, the day-to-growth increment relation and the effect of various variables on the formation of growth increments of tunas need to be investigated further.

The many studies on age and growth of skipjack hard parts such as vertebrae and dorsal spines tuna, Katsuwonus pelamis, have primarily were interpreted to determine age and growth of utilized three basic methods. Brock (19541, skipjack tuna by Aikawa and Kat0 (1938), Yokota Schaefer (1961), Kawasaki (1965), Joseph and et al. (1961), Shabotiniets (1968),Bath (19'721,and Calkins (19691, Yoshida (19711, Marcille and Chi and Yang(l973). Numerous reviews have been Stequert (1976a1, and Diaz3 determined growth written on the subject and the lack of agreement rate and estimated the age of skipjack tuna by on the aging and growth rate of skipjack tuna has examining modal progression in length-frequency frequently been noted. distributions. Yamashita and Waldron (1959), Likewise, many studies have been conducted on Shaefer et al. (1961), Clemens and Roedel (1964), age and growth of yellowfin tuna, Thunnus alba- Rothschild (196'71, and Joseph and Calkins (1969) cares. Moore (1951),Yabuta and Yukinawa (19571, used data from tagged skipjack tuna to determine Hennemuth (19611, Davidoff (19631, Dim (1963), growth rates. Wild and Foreman (1980) estimated Le Guen et al. (1969), Yang et al. (19691, Le Guen the growth rate of eastern Pacific skipjack tuna and Sakagawa (1973), and Marcille and Stequert from the recapture fork length, the known period (1976b)have estimated age and growth rate by the of growth, and the linear change in an otolith analysis of modal progression in either length or dimension following a tetracycline injection which weight frequencies. Blunt and Messersmith was used to estimate length at marking. Marks on (1960), Schafer et al. (1961),and Bayliff4 used re- sults of their tagging experiments to determine 'Southwest Fisheries Center Honolulu Laboratory, National the growth rate of yellowfin tuna in the eastern Mpne Fisheries Service, NOAA, Honolulu, HI 96812. Pacific. Wild and Foreman (1980) estimated the Southwest Fisheries Center Honolulu Laboratory, National Manne Fisheries Service, NOM, Honolulu, Hawaii: present growth rate of eastern Pacific yellowfin tuna by address: Easy Rider CorporaQon. 1050 Koloa Street, Honolulu, HI, 96816. Bayllff, W H 1973 Observations on the growth of yellow- Dim, E. L. 1966. Growth of skipjack tuna, Katsurvonus fin tuna in the eastern Pacific Ocean derived from tagging exper- pelnrnrs, in the eastern Paafic Ocean. Unpubl. rep., 18 p. iments Unpubl rep, 26 p Inter-Am Trop Tuna Comm , La Inter-Am. Trop. Tuna Comm., La Jolla, Calif. Jolla, Calif

accepted Au sf 1980. 151 %%$BULLETIN. %L. 79. NO. 1.1981 FISHERY BULLETIN. VOL 79. SO I their tetracycline-otolith method. Aikawa and identified on the basis of skeletal characters given Kat0 (1938, Nose et al. (19571, Yabuta et al. (19601, by Matsumoto et al. (1972) and descriptions of Tan et al. (1965), and Shabotiniets (1968) inter- Thunnus livers by Godsil and Byers (1944) and preted marks on scales, dorsal spines, and the cen- Gibbs and Collette (1967). trum of vertebrae to estimate age and growth. The caudal rays were missing from most tuna These studies were performed on commercial- specimens collected from stomachs. Fork lengths sizedfish(>2 kg); growthduringearlylife(<2 kg) were estimated by increasing standard lengths by has yet to be examined. 3 .3%(Matsumoto5). Pannella’s reports (1971, 1974) provided cir- Heads from which the sagittae were not im- cumstantial evidence that the smallest discern- mediately removed after collection were frozen or ible growth increments in the sagittae (otoliths)of preserved in 75% isopropanol. fish are deposited daily. More recent studies pro- In tunas species cleaned the sagittae by teasing or brushing off the of teleosts. In the study of the short-lived en- sacculus and nerve endings. Sagittae that were graulid Stolephorus purpureus, the information not mounted immediately were stored in distilled gained from the reading of sagittae was utilized in water or 4@%0isopropanol, but were then mounted the construction of a growth curve for the first 190 within a year. d after yolk-sac absorption (full life cycle) After removal and cleaning, sagittae from tunas (Struhsaker and Uchiyama 1976). In the present >45 cm FL were etched in a 1%solution of HCl for paper, growth curves are presented for central 3-5 min. The otoliths were then rinsed with sev- Paciiic skipjack tuna to an age of about 3 yr, based eral changes of water, mounted in Euparal: and, on a sample of 51 fish, and for yellowfin tuna to in most cases, permitted to clear for 4 wk or more. about 2 yr, based on 14 fish. Counts on sagittae Short lengths of monofilament line prevented con- from 20 skipjack tuna from the eastern Pacific and tact of the otolith with the glass cover slip. 5 skipjack tuna from Papua New Guinea are also Increment counts were made from the core,’ the given. The results are discussed in relation to ear- center of the nucleus, to the tips of the rostrum, lier age and growth studies of these species. antirostrum, and postrostrum (terminology of Messieh 1972) for most sagittae. On sagttae from METHODS fish >60 cm FL, counts were made only to the rostrum and postrostrum. When the edge of the Otolith Preparation and Counting rostrum and postrostrum was fringed with irregu- lar projections, counts were made on the projec- The central Pacific skipjack and yellowfin tunas tions leading to the point. Specimens were were caught in the vicinity of the Line Islands and examined at magnifications of 200-800 X. A mi- Hawaii. All specimens >20 cm FL (fork length) croscope with a zoom feature was found to be use- are samples taken from commercial fisheries or ful, as the width of daily increments varied. caught by trolling. Specimens <20 cm FL are from Counting increments in whole mounted otoliths stomach contents of troll-caught skipjack tuna becomes progressively more difficult with increas- and regurgitations of a seabird, Sula sp., after it ing specimen sue. Experience is best obtained by landed on the deck of a research vessel. begmning with otoliths from young fish and pro- Juvenile skipjack tuna from stomach contents gressing through older fish. The initial counts en- were identified by vertebral counts and skeletal characters given by Godsil and Byers (1944) and 5W.M. Matsurnoto, Southwest Fisheries Center Honolulu Gibbs and Collette (1967). In one case, only the Laboratory, National Marine Fishenes Service, NOAA. Hon- anterior portion of a juvenile skipjack tuna was olulu. HI 96812, pers. comrnun. October 1974. “Reference to trade names does not imply endorsement bv the collected; standard length ISL) was estimated National Marine Fisheries Service, NOAA. from the length of the precaudal vertebrae using ’Terminology agreed upon at the Otolith Workshop, Scnpps Institution of Oceanography and Southwest Fisheries Center. the equation given by Yoshida (1971).A small (7.0 National Manne Fishenes Service, NOAA, La Jolla. Calif.. 12-16 cm FL) yellowfin tuna specimen was tentatively July 1976. 152 UCHIYAMA and STRUHSAKER: AGE AND GROWTH OF SKIPJACK AND YELLOWFIN TUNAS able the investigator to determine the best path to days, we calculated a growth curve for central follow from the core to the edge of the otolith. Pacific skipjack tuna, eastern Pacific skipjack Eventually, the counts either converge on a value tuna, and central Pacific yellowfin tuna for com- or repeated identical counts are obtained. The parison with other studies. The von Bertalanffy number of counts required to determine age is growth parameters were estimated on an annual dependent on the readability of the otolith. An basis using the computer program BGC3 (Abram- average of about 20 counts was made for fish >1 yr son 1971). old. We found that yellowfin tuna sagittae were easier to read than those of skipjack tuna. In yel- ESTABLISHING THE lowfin tuna, the increments are wider and can be GROWTH INCREMENT-DAY RELATION examined at a lower magnification (ZOOx), which provides a broader view and greater depth of field. The only direct evidence we have that a number The increment counts on 15 skipjack tuna and 3 of growth increments equal the same number of yellowfin tuna sagittae were verified by a second days came from the serendipitous opportunity to reader whose counts were within 9% (5.4% aver- examine skipjack and yellowfin tunas under age deviation) of the original counts except for one known captive conditions. These fishes were not which was 17% off the original count. held under strict experimental conditions and their primary use was not for aging studies; how- Statistical Analysis ever, a detailed record on the amount of food con- sumed by each fish during the experiment was The parametem of linear growth stpnzaa were maintained. The experiment was similar to that determined by the use of LINFIT, a computer prc+ used for nehu, S. pwpureus (Struhsaker and gram (Kamer") which uoed the ordinary least Uchiyama 1976), and was carried out at the squares procedure to fit two or three straight lines Kewalo Research Facility of the Honolulu to bivariate data. Join pointa, also known as break Laboratory points, are the places where one regime ends and The stress of being hooked, transported, and another begins; these are a~eumedto exist. The confined in the community tanks at the Kewalo range of the explanatory variable in which the join Research Facility, as well aa the taking of little or pointa are expected to occur must be designated. no food during the first week of captivity, probably Given the range for thee join points, the program all contributed to the formatioh of a check mark on performs the ordinary least squares procedure on the otolith (Figure la, b). When the tuna were each possible combination of regimes. The result- sufficiently recovered to feed normally, they re- ing output indicates the partitioning scheme, the ceived a daily ration which apparently was intercept and slope of each fitted line representing adequate to maintain life but inadequate for nor- a regime, the residual sum of squares for each mal increment formation. Perhaps very thin in- regime, the combined residual sum of squares for crements were formed during this period, which the model, and the values of the dependent and might have added prominence to the check mark. explanatory variables at the join points. The When these tunas were fed to satiation through- linear growth stanzas used in this paper were out the day, the widths of the increments increased selected under the following conditions: 1) and became countable. minimized combined residual sum of squares for Under low magnification (200 x 1, growth incre- the model and 2) each join point associated with a ments formed on the edge of a saGtta during the partitioning scheme has a value for the explana- experiment were not as well defined as those of a tory variable which lies between the last data tuna captured in the wild. The increments ap- value in the regime to the lee and the first data peared thinner than normal when examined value in the regime to its right. under high magnification (400x). For this reason, On the assumption that the maximum number a sagitta was first examined under low power of increments approximates the age of the fish in (200x1 to locate the check mark and then examined under high power (400 X) to enumerate the growth increments formed during the experi- 8Kamer, G. A computer program for fittmg straight lines to mental feeding period. Although growth incre- rwmented data. Manuscr. in prep. Southwest Fishenes Center Honolulu Laboratory, National Manne FishenesService, ments occurred all along the periphery of the NOM,Honolulu, Hawaii. sagitta, the full array of increments corresponding 153 FISHERY BULLETIN VOL. 79.NO. 1

FIGURE 1.-Check mark, indicated by arrow, separates the environmentally marked increments from previous growth increments at ai tip of skipjack tuna sagitta rostrum: b) postrostrumof same skipjack tuna sagitta.

to the feeding period formed primarily on the tips trolled. Therefore, these data are considered ten- of the rostrum and postrostrum (Figure la, b). tative and in need of replication by rigorous ex- The highest count attainable corresponded with perimental methods. the number of days the tuna were fed to satiation, Wild and Foreman (1980) were able to show a 1:l thus confirming the growth increment-day rela- (day-to-growth increment) relationship for yel- tion (Table 1). The number of increments formed lowfin tuna, 40-110 cm FL. However, their day-to- after the check mark usually exceeded the number growth increment relation for skipjack tuna was of feeding days because the tunas continued to live significantly <1:1. Although an experiment where beyond the feeding period. During this latter the fish lived in its natural environment was period, the tunag either received a daily ration or highly desirable, there was no control over vari- starved. Great care was taken to avoid double ables and a record of variables which the fish counting of an increment where the sagitta was might have encountered was unavailable. thin. The observations on these specimens were Variables such as the amount of food a fish con- not long term and conditions were not fully con- sumes (Struhsaker and Uchiyama 1976; Methot 154 I

UCHIYAMA and STRUHSAKER AGE AND GROWTH OF SKIPJACK AND YELLOWFIN TUNAS

TABLE1 -Expenmental data on marked daily growth increments in skipjack and yellowfin tunas Experiment& Fak lengm Date of death Length of feed- No of marked animals (an) FMngperlod per sampling ing period (d) inuements Skipjack tuna 3 48 3 23 Aug -22 Sept 6 Ocl 30 33 Skiplack lune 4 453 9-14 OCl 27 Ocl 5 7 Skipjack tuna 5 493 15-22 Ocl 27 Oct 7 8 Skipjack luna 6 450 19-30 Ocl 4 Nov 11 14 Yellowfintuna 1 52 2 2 -26 Aq 4 Sept 24 24 Yellowtin tuna 2 52 0 20 Aug -19 Sept 29 Sept 30 31

and Kramer 1979), temperature (Taubert and TABLE 2.-Length-age regression parameters for the three Coble 1977; Methot and Kramer 1979), and age of linear growth stanzas of skipjack tuna: N = number of data fish (Pannella 1971; Brothers et al. 1976) have been and RSS = residual sum of squares. demonstrated to affect the formation of daily IntwSectlOns Fork growth rings on the sagitta. In our experiments Slanzas N intercept Slope RSS Years length(cm) with nehu, skipjack tuna, and yellowfin tuna, the 1 11 00552 584167 30910 amount of daily ration appeared to have an influ- 04616 270192 2 35 136402 28.9853 17 6038 ence on otolith growth increments. Fishes fed once 19921 71 3812 daily did not have clear otoliths with countable 3 5 51 6918 98838 02761 growth increments. Only when the fishes were fed Tom RSS 20.9709 to satiation throughout the day were countable growth increments formed. In the experiment on domly about the x-axis, signifying a good fit (run's the effect of winter conditions on the formation of test 2 = 0.39678, P = 0.6892). On the other growth increments by Taubert and Coble (1977), hand, the residuals for the von Bertalanffl curve the green sunfish, Lepomis cyanellus, lowered oscillated about zero and were largest at break- their activity level and fed less when the tempera- points between linear stanzas and at the midpoint ture fell below 10"C. Wild and Foreman (1980) also of the stanzas, thus suggesting a deviation from suggested that the difference in their restilts be- randomness (run's test: 2 = - 3.32287, P

117*LlumcuIM(soC 3.N.51, FL 3.7-80.3cml 102.0cn 0.55 -0.02yr I -LINEAR GROWTH STAGES

3 6 9 12 15 18 21 24 27 30 33

FIGURE 2.--Gmwth curve of skipjack tuna in the central Paafic as determined by otolith examination. bear growth stanzaa detennined by LINFIT (see text). For parameters of growth stanas, see Table 2. rates up to 65 cm FL; beyond 65 cm FL, Brock's tuna (Figure 5). Ofthe 20 specimens examined, 11 curve departs from ours and approaches an were caught off Baja California, Mexico. The other asymptote more rapidly. The difference in the nine were caught in the eastern Pacific west of the growth rates above 65 cm may be due to two factors Inter-American Tropical Tuna Commission's Yel- which would affect the modea of large (>6.8kg) lowfin Regulatory Area. Most of these nine speci- skipjack tuna: differential fishing or total mortal- mens had age-length relationships similar to ity and temperature requirements of skipjack those of fish caught off Baja California, but several tuna. Barkley et al. (1978)hypothesized that large had relationships similar to specimens taken in (>6.8kg) skipjack tuna required cooler water than the central Pacific. Indications are that skipjack small skipjack tuna and therefore could tolerate tuna in the eastern Pacific Ocean off Baja Califor- the warmer surface water for relatively short nia grew at a slower rate than those in the central periods. If so, the catchability of large skipjack Pacific. tuna would be altered in the surface fishery and Our eastern Pacific skipjack tuna growth curve length-frequency modes of large skipjack tuna was compared with thase of earlier studies from would be underestimated. Our otolith age deter- the eastern Pacific (Figure 5). A growth curve minations are not affected by these factors. based on the progreesion of modes in length fre- Otolith readings were also used to examine the quencies (Joseph and Calkins 1969) is similar to age-length relationship of eastern Pacific skipjack our curve; both show good agreement between 40 156 UCHIYAMA and STRUHSAKER: AGE AND GROWTH OF SKIPJACK AND YELLOWFIN TUNAS and 65 cm FL. Growth curves determined from VON BERTALANFFY 3- CURVE tagging data (Schaefer 1961; Joseph and Calkins 4 1969) showed slower growth. 2- The sagittae of five skipjack tuna from Papua

I- New Guinea waters were examined (Figure 6).

0. These fish grew more slowly than those from the t. - R 0. 1 central Pacific area.

0. -I -3 . 0- *; *; c Central Pacific Yellowfin Tuna -2 - ltvo distinct stanzas of growth are evident for -3. the sample of 14 central Pacific yellowfin tuna (Figure 7). Linear growth is apparent for about the first 14 mo of life, aRer which time the data suggest either the beginning of another linear growth phase or an asymptotic growth process. A seg- mented model with two linear phases was fitted to the data (Table3). A von Bertalanffy growth equa- I 2 tion was also fitted to the data and the following YEARS growth parameters were obtained: L = cm; = 0.3864, and to = 0.0366 yr. FIGURE 3.- Plot of residuals from von BertalanfTy growth curve 170.3 K and linear growth stanzas ofcentral Pacific skipjack tuna shown Plots of residuals on age for both the segmental in Figure 2. model and the von Bertalanffy growth curve were

9(

I

3 2 6 4

7c I

'0 1I THIS STUDY (SI POINTS) - 102 Ocm 0 55 - -0 02yr 2 . SKILLMAN ( MALESN ONLY 1 -101 lcm -0 39 3..3 ROTHSCHILD ( UNCORRECTED ) - - 90 6cm 0 59 4 - SKILLMAN (MALES 8 FEMALES) 92 4cm 0 47 5 -BROCK 85 5cm 0 92 6 _ROTHSCHILD (CORRECTED ) -82 3cm -0 n

12 I8 24 30 36 MONTHS FIGURE 4.-A cornpanson of von Bertalanffy growth curves determined for central Pacific skipjack tuna (for full references, see text) 157 FISHERY BULLETIN: VOL. 79. NO. 1

2

3

4 5

L, L, K ‘0 i -EASTERN PACIFIC (OTOLITH ) __ -1425cm 029 -0 16yr

2-CENTRAL PACIFIC (OTOLITH1 ~~ ~ .102.0cm 0.55 -002yr 3-JOSEPH 8 CALKINS (LENGTH FREQUENCY) --I07 5 em -0.41 4 -JOSEPH 8 CALKINS (TAGGING , CORRECTED ) 88 I cm 0 43 5-JOSEPW a CALKINS (TAGGING, UNCORRECTED) 72 9cm 0 82

12 18 24 30 36 MONTHS

FIGURE 5.--lhe von Bertalanffy growth curve of skipjack tuna in the eastern Pacific as determined by otolith examina- tion and its comparison with von Bertalanffy growth curves ofprevious studies from that area and the central Pacilic (for full reference, see text).

TABLE 3.--Length-age regreesion parameters for the two linear, and was an improvement over the von Bertalanffy growth stanzas of central Pacific yellowfin tuna: N = number of curve with the increase in the number of runs from data and RSS = residual sum of squares. 7 to 9. lntersecaons The results of our study on yellowfin tuna within Fwk Stanre8 N intercept SI- RSS Yews length(cm) the size range examined agree with most earlier 1 10 0.8831 52.5837 5.7430 studies for this species from the eastern and cen- 1.2047 64.2304 tral Pacific Ocean. The results of aging by scales 2 4 25.5653 32.0854 0.4820 Tot& RSS 6.20050 (Yabuta et al. 1960) and modal progression in length-frequency distributions (Hennemuth 1961) are given for comparison (Figure 6). It has been compared (Figure 8). As with skipjack tuna, the suggested that growth of yellowfin tuna in the von Bertalanffy model gives a poorer fit than the eastern Pacific between the lengths of 50 and 100 linear segmental model. Although the probability cm is linear and that growth rates are 0.6-1.0 for the distribution of residuals to be randomly mmid (Inter-American Tropical Tuna Commis- distributed along the von Bertalanffy curve was sion 1972. 1974). significant at P = 0.05 (run’stest, table of critical values: r = 7, nl= 7, n2 = 7),clustering of pluses CONCLUSIONS and minuses occurred. The run’s test for the linear segmental model also showed randomness (r = 9, Daily growth information provides much nl = 6, n2 = 8; table of critical values, P < 0.05), greater insight into the growth patterns of teleost 158 UCHIYAMA and STRUHSAKER: AGE AND GROWTH OF SKIPJACK AND YELLOWFIN TUNAS

12 18 24 30 36 I MONTHS

FIGURE B.-Age determinations (points) of skipjack tuna from Papua New Guinea and comparison wth the von Bertalanffy growth curve of central Pacific skipjack tuna derived in th~spaper. fishes than can be gleaned using traditional an- Estimation of growth rates from daily growth nual techniques. Data presented here suggest increments on sagittae is subject to at least two three stanzas of linear growth for central Pacific possible sources of error. One is that increments skipjack,tuna ranging in size from 3 to 80 cm FL, may not be deposited due to variables such as an and that central Pacific yellowfin tuna from 7 to 93 inadequate ration, diet, temperature, age of fish, cm FL have at least one stanza of linear growth. or during some physiologically stressful activity, Our assumption that the growth increments on such as reproduction. This is apparently the case the sagittae of skipjack and yellowfin tunas are for three species of boreal gadoids investigated by deposited daily was supported by the deposition of Pannella (1971). Another source is differential experimentally induced increments on the sagit- error during increment counting. If fewer rings tae of captive fishes and the relatively good agree- are counted than actually exist, this, in addition to mept of our skipjack tuna and yellowfin tuna nondeposition of daily increments, would result in growth curves with those of previous studies overestimation of growth rate. utilizing other growth estimating techniques such as progression of modes in length-frequency dis- ACKNOWLEDGMENTS tributions and interpretation of other hard parts. Growth studies on tunas based on tagging experi- We thank Edward B. Brothers, Gary T. ments have usually slower growth rates. Sakagawa, Robert A. Skillman, Richard N. Otolith readings on specimens from three dif- Uchida, and Jerry A. Wetherall for reviewing this ferent areas suggest that there are geographical manuscript and for their suggestions for improv- variations. ing it. We also wish to thank Wilvan G. Van Cam- 159 FISHERY BULLETIN VOL 79,NO 1

130 I'I~I,,"'' I

AGE (WhTHS) FIGURE 7.-Growth curve of yellowfin tuna in the central Pacific as determined by otolith examination and compared with growth curves of previous studies from that area and the eastern Paclfic. Linear growth stanzas determined by LINFIT (see text). For parameters of growth stanzas, see Table 3. pen and Howard 0. Yoshida for their editorial em tropical Pacific Ocean. [In Engl. and Span.] Inter- help. We are especially indebted to Gary L. Kamer Am. Trop. Tuna Comm. Bull. 7:295-396. and Jeffrey J. Polovina for assisting with the BARKLEY, R. A,. W. H. NEILL, AND R. M. GOODING. statistical problems encountered. Marian Y. Y. 1978. Skipjack tuna, Katsuwonus pelamis, habitat based on temperature and oxygen requirements. Fish. Bull., Yong assisted with the data processing and Glen US.76:653-662. Sugiyama verified some of the age determina- H. BARKMAN.R. C. tions. We are grateful to Sherry Steffel for sharing 1978. The use of otolith growth rings to age young Atlantlc her dataon feeding records and otoliths of skipjack silversides. Menidia rnenidia. Trans. Am. Fish. Soc. and yellowfin tunas from her experiment. 107:790-792. BATS, B. S. LITERATURE CITED 1972. Age and growth of the skipjack tuna, Katsuwonus pelarnrs (Linnaeusl, in North Carolina waters. Chesa- peake SCI. 13237-244. ABRAMSON. N. J. Icompiierl. 1971. Computer programsfor fish stock assessment. FA0 BLUNT. C. E., JR.. AND J. D. MESSERSMITH. Fish. Tech. Pap. 101 1149 p.]. 1960. Tuna taggmg in the eastern tropical Paafic. 1952- AIKAWA, H.. AND M. KATO. 1959. Calif. Fish Game 36:301-369. 1938. Age determinations of fish. I [In Jpn., Engl. BROCK, V. E. synop.] Bull. Jpn. Soc. Sci. Fish. 7:79-88. iEngl. transl. 1954. Some aspects of the biology of the aku,Katsuwonus by W G. Van Campen, 1950. US. Fish Wildl. Sen., Spec. pelarnrs. in the Hawaiian Islands. Pac. Sci. 8:94-104. Sci. Rep. Fish. 21, 22 p.) BROTHERS. E. B.. C. I? MATHEWS. AND R. LASKER. ALVERSON. F. G. 1976. Daily growth increments In otoliths from larval and 1963. The food of yellowfin and skipjack tunas in the east- adult fishes. Fish. Bull.. U.S. 74:l-8. 160 UCHIYAMA and STRUHSAKER. AGE AND GROWTH OF SKIPJACK AND YELLOWFIN TUNAS

3 JOSEPH, J.,AND T. F? CALKINS. 1969. Population dynamics of the skipjack tuna (Kat- VON BERTALANFFY CURVE . 2- .. suwonus pelanrsi of the eastern Pacific Ocean. [In Engl. and Span.] Inter-Am. Trop. Tuna Comm. Bull. 13,273 p. I- KAWASAKI,T. RO 1965. Ecology and dynamics of the skipjack population I. Resources and fishing conditions. [In Jpn.] Jpn. Fish. -I - Resour. Prot. Assoc. 8-1:l-48. (Translated by M. F? Miyake. 1967,54 p., Inter-Am. Trop. Tuna Comm.. La Jolla, Calif., -2 ~ LE GUEN, J. C.. F. BAUDIN-LAURENCIN,AND C. CHAMPAGNAT. 1969. Croissance de l'albacore (Thunnus albacaresi dans les regons de Pointe-Noire et de Dakar. [In Fr., Engl. summ.1 Cat. O.R.S.T.O.M. sir. Ocianogr. 7:19-40. LINEAR STANZAS LE GUEN. J. C., AND G. T. SAKAGAWA. 1973. Apparent growth of yellowlin tuna from the eastern Atlantic Ocean. Fish. Bull., U.S.71:175-187. MARCILLE, J., AND B. STEQUERT. 1976a. Etude preliminaire de la croissance du listao (Kat- sumnus pelamrs) dans l'ouest de I'Ocean Indien tropi- -0 I 2 3 cal. Cah. O.R.S.T.O.M.ser. Oceanogr. 14:139-151. YEARS 1976b. Croissance des jeunes albacores Thunnus alba- cams et patudos, Thunnus obesus de la cote nord-ouest de FIGURE 8.-Plots of residuals from von Bertalanffy growth Madagascar. Cah. O.R.S.T.O.M. ser. Oceanogr. 14:153- curve and linear stanzas of central Pacific yellowfin tuna shown 162. in Figure 7. MATSUMOTO,W. M., E. H. AHLSTROM. S. J0NES.W. L. KLAWE. W. J. RICHARDS,AND S. UEYANAGI. 1972. On the clarification of larval tuna identification CHI, K.-S., AND R.-T YANG. particularly in the genus Thunnus. Fish. Bull., U.S. 1973. Age and growth of skipjack tuna in the waters 70:l-12. also Tr. Atl. Nauchno-Issled. Inst. Rybn. Khoz. around the southern part of Taiwan. [In Engl., Chin. Okeanogr. 53~12-33,1973[In Russ.1.) abstr.] Acta Oceanogr. Taiwan. 3399-221. MESSIEH. S. N. CLEMENS, H. B., AND P. M.ROEDEL. 1972. Use of otoliths in identifying hernng stocks in the 1964. Tagging experiments on tuna and mackerel in the southern Gulf of St. Lawrence and adjacent waters. J. eastern Pacific. Proc. Spp. Scombroid Fish., Part 11. Fish. Res. Board Can. 29:1113-1118. Mar. Biol. Assoc. India, Symp. Ser. 1769-784. METHOT. R. D.. JR., AND D. KRAMER. DAVIDOFF,E. B. 1979. Growth of northern anchovy, Engmulis mordar. 1963. Size and year class composition of catch, age and larvae in the sea. Fish. Bull., U.S.77:413-423. growth of yellowfin tuna in the Eastern Tropical Pacific MOORE, H. L. Ocean, 1951-1961. [In Engl. andSpan.1 Inter-Am. Trop. 1951. Estimation of age and growth of yellowfin tuna Tuna Comm. Bull. 8:201-251. iNeothunnus rnacropterus~in Hawaiian waters by size DIU, E. L. frequencies. US.Fish Wildl. Serv. Fish. Bull. ,52:133- 1963. An increment technique for estimating growth 149. parameters of tropical tunas, as applied to yellowfin tuna NOSE. Y., H. KAWATSU.AND Y. HIYAMA. (Thunnus albacamsl. an Engl. and Span.] Inter-Am. 1957. Age and growth of Pacific tunas by scale read- Trop. Tuna Comm. Bull. 8:383-416. ing. @n Jpn.. Engl. summ.1 In Suisan Gaku Shusei, GIBBS, R. H., JR., AND B. B. COLLETI'E. Tokyo Univ. Press, p. 701-716. 1967. Comparative anatomy and systematics of the tunas. PANNELLA.G. genus Thunnus. US. Fish Wildl. Serv.. Fish. Bull. 1971. Fish otoliths: dady growth layers and periodical 66:65-130. patterns. Science (Wash.. D.C.1 173:1124-1127. GODSIL,H. C.. AND R. D. BYERS. 1974. Otolith growth patterns: an aid in age determina- 1944. A systematic study of the Pacific tunas. Calif. Fish tion in temperate and tropical fishes. In T. B. Bagenal Game, Fish Bull. 60, 131 p. leditor). Proceedings of an international symposium on HENNEMUTH.R. C. the ageing offish, p. 28-39. Unwn Brothers. Surrey, Engl. 1961. Size and year class composition of catch. age and ROTHSCHILD. B. J. growth of yellowfin tuna in the Eastern Tropical Pacific 1967. Estimates of the growth of skipjack tuna (Kat- Ocean for the years 1954-1958. [In Engl. and sumnus pelamisl in the Hawaiian Islands. Indo-Pac. Span.] Inter-Am. Trop. Tuna Comm. Bull. 5:S-llZ. Fish. Counc., Proc. 12th Sess.. Sect. 2:lOO-lll. INTER-AMERICAN TROPICAL TUNACOMMISSION. SCHAEFER.M. B. 1972. Annual report of the Inter-Amencan Tropical Tuna 1961. Append% A. Report on the investiqations of the Commission, 1971. [In Engl. and Span.] La Jolla, Inter-hencan Tropical Tuna Commission for the year Calif., 129 p 1960. [In Engl. and Span.] Inter-Am. Trop. Tuna 1974. Annual report of the Inter-American Tropical Tuna Comm., Annu. Rep. 1960.40-183. Commission. 1973. [In Engl. and Span.] La Jolla. SCHAEFER. &I.B.. B. M. CHATWIN. AND G. C BROADHEAD. Calif., 150 p. 1961. Tagging and recovery of tropical tunas. 19%- 161 FISHERY BULLETIN: VOL. 79, NO. 1

1959. [In Engl. and Span.] Inter-Am. Trop. Tuna racycline. [In Engl. and Span.] Inter-Am. Trop. Tuna Comm. Bull. 5:341-455. Comm. Bull. 17:509-560. SHABOTINIETS, E. I. YABUTA, Y., AND M. YUKINAWA. 1968. Opredelenie vozrasta tuntsov Indiiskogo okeana 1957. Age andgrowth ofyellowfin tuna (Neothunnusmac- (Age determination of Indian Ocean tunas). [In ropterus) in Japanese waters by size frequencies. [In Russ.] Tr. VNIRO 64, Tr. AzcherNIRO 28:374-376. Jpn., Engl. summ.] Rep. Nankai Reg. Fish. Res. Lab. (Translated by W. L. Klawe, 1968, 5 p.. Inter-Am. Trop. 5127-133, Tuna Comm., La Jolla, Calif) YABVTA, Y., M. YUKINAWA, AND Y. WARASHINA. SlXUHASKER, E,AND J. H. UCHIYAMA. 1960. Growth and age of yellowfin tuna. 11. Age detenni- 1976. Age and growth of the nehu,Stolephonrspurpureus nation (Scale method). [In Jpn., Engl. summ.] Rep. (Pisces: Engraulidae) from the Hawaiian Islands as indi- Nankai Reg. Fish. Res. Lab. 263-74. cated by daily growth increments ofsagittae. Fish. Bull., YAMASHRA, D. T., AND K. D. WALDRON. US.74:9-17. 1959. Tagging of skipjack in Hawiian waters. Pac. Sci. TAN. H.-C., Y. NOSE, AND Y. HIYAMA. 13:342-348. YANG,R.-T.. Y. NOSE, AND HIYAMA. 1965. Age determination and growth of yellowfin tuna, Y. A comparative study on the age and growth of yel- Thunnus albacares Bonnaterre by vertebrae. Bull. Jpn. 1969. SOC.Sci. Fish. 31:414-422. lowfin tunas from the Pacific and Atlantic Oceans. Bull. Far Seas Fish. Res. Lab. (Shimizu) 2:l-21. TAUFIERT,B. D., AND COBLE. D. \V. YOKOTA, T., M.TORIYAMA, F. KANAI,AND S. NOMURA. Daily ringsin otolithsofthreespeciesofLepomis and 1977. 1961. Studies on the feeding habit of fishes. an Jpn.. Tilapta mossambica. J. Fish. Res. Board Can. 34:332- Engl. summ.] Rep. Nankai Reg. Fish. Res. Lab. 14,234p. 340. YOSHIDA,H. 0. WILD,A., AND T. J. FOREMAN. 1971. The early life history of skipjack tuna, Katsuwonus 1980. The relationship between otolith increments and pelamcs, in the Pacific OQM. Fish. Bull., US. 69545- time for yellowfin and skipjack tuna marked with tet- 554.

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