Previous Page Table of Contents Next Page


A REVIEW OF THE BIOLOGY AND FISHERIES FOR YELLOWFIN TUNA, THUNNUS ALBACARES, IN THE EASTERN PACIFIC OCEAN (contd.)

12. POPULATION DYNAMICS

12.1 Recent Adjustments to the Basic Data

In 1989 the IATTC staff introduced several analytical modifications to its assessments of the yellowfin stock in the EPO (IATTC, 1991a). One of them was the separate treatment of yellowfin inside and outside the CYRA. In the past, tagging experiments (Section 6.3) and studies on population structure (Suzuki et al., 1978) supported the view that the fish inside the CYRA represented the eastern Pacific stock while those outside the CYRA, but east of 150°W, belonged to the stock of the central Pacific. This separation was also upheld by historic differences in the relationship between catch and effort in the two regions. Inside the CYRA catch versus effort generated a curvilinear production model (see below) with the implied need for regulation, but outside the CYRA the linear relationship suggested that no constraints were necessary, at least during the 1968–88 period (IATTC, 1989). However, the fishery has been unregulated since 1979, and in the interim the distribution of effort has become more continuous over the adjacent areas. As a result, the increased amount of data has revealed that since the early 1970s the average sizes of fish in the catches (Figure 15, upper panel) and the CPDFs (Figure 15, lower panel) in both areas displayed similar trends. Analyses carried out in 1990 therefore treated yellowfin to the east of 150°W as a single stock, and this practice will probably be continued in the future. The growth relationships based on otolith increments (Wild, 1986) have also been incorporated in the analyses, and they indicate that the growth rate in length and weight is more rapid than previously thought. As mentioned earlier (Section 5.3), studies on sex ratios point to the virtual disappearance from the fishery of females larger than 140 cm, and this has prompted the use of different natural mortality rates for the sexes. Additionally, the length at recruitment has been adjusted downward from 40 to 30 cm, and the number of recruits has therefore increased as a result of their entering the fishery two months earlier. Finally, the speed of convergence and accuracy of fishing mortality estimates prepared through cohort analysis have been improved by using monthly, rather than quarterly, calculations. Despite all of these adjustments the biomass estimates (next Section) have not changed to a large extent, and the trends in the fishery remain intact (IATTC, 1991a).

Figure 15

Figure 15. Average weights of yellowfin caught (upper panel) and average catches of yellowfin per day's fishing (lower panel) by Class-6 purse seiners in the eastern Pacific Ocean. (Reproduced from IATTC, 1991a).

12.2 Biomass Analyses

The IATTC staff has collected length-frequency samples from the yellowfin fishery in the EPO since 1954, and it has access to the corresponding information for 1951–54 collected by the California Department of Fish and Game. As a first step in the development of biomass estimates, the samples and total landings for each year are stratified by month, by 13 areas, and by gear type. Samples within strata are weighted and combined and, by procedures involving the growth-in-length relationship, the numbers of fish caught of each age group of the X and Y cohorts are estimated. Total monthly estimates of these fish within age groups and cohorts are obtained by summation across areas and gear types. When these monthly estimates are arranged chronologically in ascending order of years, the data are amenable to the application of cohort analysis, or the back-calculation to recruitment of all the numbers of fish in a cohort that contributed to its catch history. For this purpose, an annual, instantaneous natural mortality rate (M) of 0.8 is used for males of all ages, while for females M is set at 0.8 for the first 30 months in the fishery and allowed to increase linearly to 6.5 at 80 months. In practice these rates are allowed to vary somewhat for each cohort. Values of the annual instantaneous fishing mortality (F) used to initiate the back calculations are chosen on the basis of experience, seasonal variations in effort, and data on completely-fished age groups whose F values have converged toward stability. The results of these calculations appear in Table 5 as the quarterly average number of fish in each age group for each cohort during the 1967–89 period. The average weights of the fish during each quarter, beginning with the quarter (qtr.) they are recruited into the fishery were also estimated to be:

Qtr.lbkg
1   0.84  0.38
2   1.80  0.82
3   3.52  1.60
4   6.33  2.87
5  10.58  4.80
6  16.60  7.54
7  24.6211.18
8  34.7615.78
9  47.0121.34
10  61.2427.80
11  77.1935.80
12  94.5442.92
13112.8951.25
14131.8659.86
15151.0768.59
16170.1777.26
17188.8685.74
18206.9093.93
19224.11101.75
20240.35109.12
21255.52116.01
22269.60122.40
23282.55128.28
24294.40133.66
25305.18138.55
26314.95142.99
27323.75146.98

The average annual biomass is obtained by multiplying the data in Table 5 by the corresponding quarterly weight and averaging over four quarters. These biomass estimates appear in the bottom panel of Figure 14.

Compared to the abundance indices derived from CPDF or searching time, those calculated by the above method appear to be smoothed, or less sensitive to smaller fluctuations. Trends are preserved, however, including the decline during the mid 1970s to 1982 that resulted from escalating effort and the capture of both small and large fish. The recovery of the fishery also began in 1982, according to the cohort biomass estimate, one year earlier than the other indices began to respond. This may be because the cohort biomass is more responsive to the contribution of recruits. By 1985 the biomass appears to have stabilized at more than twice the level in 1982. While this may be partially the result of increasing trends in average recruitment (Figure 16 and Table 4), the tendency of the fishery to concentrate on larger fish must also have had a beneficial and substantial impact.

TABLE 5. Estimated average numbers of yellowfin in the eastern Pacific Ocean, in thousands, for the X and Y cohorts during the 1967 through 1989 seasons. (Reproduced from IATTC, 1991a).

Year Año  Quarter TrimestreX Cohort--Cohorte XY Cohort--Cohorte Y
0IIIIIIIVVVI0IIIIIIIVVVI
19671014437831512004011065001799127857592006734
 201182057429232768341373411277717195231425427
 3089963996712196663430572816713433641084422
 4210817217316752114253272502964861064250843618
                
19681017259569623793691084302045950578101756729
 2014124388412182438435253041522034595561235424
 3011518283887216967292071896352450375934420
 4235689214226263612454241694275891947259733616
                
19691019296705317974239344013643540812931755829
 201569349491403248723627047900532266311214724
 30124763887108317058292214562452457396923820
 4270419358307975212247241812846371883242723116
                
19701022139626522064789336014561297513141585725
 2018119372713102337231266271042517197681024620
 3014682281691715158252180070911326475773817
 43457211365213259510546211783252551010289603114
                
1971102830282311562375793801429737746791534825
 202299656541186232603127402988522834271033821
 3018455441187115948252243573511706280783117
 41973914168348154710939211836557901271152612614
                
1972101616010615219631478320145304023694804821
 201321365501070175592636708107392811324463817
 301072748787448348213005477692136161313114
 41661786323485466443817246036127159271242511
                
1973101360568822419227313101936642021082411721
 20108475147132110624256856892792548592261517
 30873340979425619215613952021893263171314
 44654869533203466301617456293624145684131011
                
19741038110531319822381713033755251899023108
 2030958402911311421310289131822517056461387
 302477932427835510823669100061301316966
 4363881931825174632287184767139976148755
                
1975102978012768170927811701451750286837954
 20236958546100213576369141068334843872843
 30177896092618495530134802723711971133
 4174121323745163561944240596428158885632
                
1976101425197982930212113016120493811113352
 201153758241988916328482930937226401342
 3089114110126531522328556162327243931
 418656642731337021542185723802144578621
                
197710151944864226626683013699267510563552
 2012028319415041556369564798818717142342
 3092542219680585256610459410872581231
 43427266791561312154243514319778076731
                
19781027913487511791809302898823245703252
 2019549331376711563426471360215743881842
 30121732464528555234214795511692311031
 43951188901760298144225833574285580431
                
19791032319593812681577301677940145343922
 20242853918770895339983976522243472322
 30164763003504354231792605715251811321
 4301049376224632222322047941641047116911
                
19801024140621116191659201355331096035261
 201685031761205763242578734323193831621
 309968225584832223440046281599189711
 4219976650165956316212657333761135102411
                
198110177314726116230910101918625718385121
 2012690303981713641310991115117975441421
 307698203954964312516357161295235810
 423899412113593204231192073360828142510
                
19821019146253796818010201295221215714031
 20125451720669102523888681569463802031
 307612130744650423070051146781851221
 43125353131022254242121003395144894720
                
198310254054021802796201488432012752021
 20193292933612283141428101882478152721
 301329522324111321337667542174183511
 4397529868171027081126865601697643311
                
19841032240796013151265102116847395971921
 20252816059985563138674163083272351821
 30178054770666182131420125682299151211
 441355122793587360621255869439150759110
                
19851033858941726281432102083970139332011
 202707873101759571134462162254780456711
 302175652771075171127976127363127174211
 445636168053998589411227439976203856110
                
1986103717510302292730121017305758412792510
 203011373171827961042169133025003602710
 30239625848104221103432196503266169310
 448943186664629544710261596334220655200
                
1987103980414361349428841019754465714631610
 20316791011421411582162542143582996856510
 302375375481222581050984110672039327210
 44073115641509163319104087587051427145110
                
1988103323611269376233651030323666510234410
 2025862748827291192155012170894945604610
 301744853651925381044877110703711309110
 439380119363651126614103577172582513154010
                
198910322148054259377651026364477417537300
 202468148391568439214578119377301510672500
 3018275267594025310373981479417515251600
 4450081275114875021591029920111539802671100

12.3 Yield-Per-Recruit Analysis

There does not appear to be a discernible relationship between the biomass of large fish in the EPO in any given year and the number of recruits to the fishery one year later (Figure 17; IATTC, 1991a). Constant recruitment has therefore usually been assumed in yield-per-recruit analysis. Recent changes in the distribution of effort though, have helped to identify two major periods in which differences in age-specific fishing mortality rates have caused a significant change in the yield per recruit. For example, beginning in the last few months of 1973, the purse-seine fleet began to focus increasingly on the smaller fish associated with floating objects. This re-direction of effort was partly a response to the diminishing numbers of large fish, but it may also have been a reaction to the increased awareness of and public response to dolphin mortality. During the 1978–82 period the distribution of effort had evolved to the point that the age-specific mortalities of small, medium and large fish were similar. In subsequent years, however, effort was again directed toward larger fish, so that by 1985–89 their age-specific mortality was substantially greater than that of smaller fish. As mentioned earlier, a rising trend in recruitment (Figure 16) was also evident during this latter period. Collectively, these changes in fishing mortality patterns and recruitment, and recognition that recruitment occurs at 30 cm, are reflected in the yield-per-recruit diagrams for each period (Figure 18). The comparative effects on the yield-effort relationship are also more clearly illustrated in Figure 19. In each diagram the x-axis represents a multiple of effort in which the value 1.0 is the average effort for the particular period.

Figure 16

Figure 16. Estimated initial recruitments of yellowfin in the eastern Pacific Ocean, with the average recruitments for 1967–75, 1976–82, and 1983–89. (Reproduced from IATTC, 1991a).

Figure 17

Figure 17. Relationship between stock and recruitment for yellowfin in the eastern Pacific Ocean for 1967 through 1989. Each dot represents the average recruitment of the X and Y cohorts. (Reproduced from IATTC, 1991a).

Figure 18

Figure 18. Relationships among size at entry, fishing effort, and yield per recruit for yellowfin for two different patterns of age-specific fishing mortality. (Reproduced from IATTC, 1991a).

Figure 19

Figure 19. Yields for average recruitment and age-specific fishing mortality similar to that of 1978–1982 and for high recruitment and age-specific mortality similar to that of 1985–89. (Reproduced from IATTC, 1991a).

The major differences between the two periods for the surface fleet are summarized below:

Average1978–19821985–1989Percent Change
Effort (x 10-3 days)30.9620.24-35
CPDF (mt)5.3913.26+146
Catch (x 10-3 mt)167.2266.1+59
Recruitment (x 10-3)70.795.0+34
Y/R (kg)2.263.04+34
Biomass (x 10-3 mt)243471+94

It is reasonable to assume that the increased catch during the 1985–89 period stems from the increase in biomass, and in turn, that the biomass had benefitted from the reduction in effort and the increase in recruitment. These factors alone, however, do not explain the disproportionately large increase (146 percent) in CPDF. As a rough estimate, only 64 percent of this increase can be accounted for by changes in effort and recruitment. The remaining 36 percent stems from the reallocation of effort toward the older and larger fish in the stock, further increasing the yield per recruit. The use of less effort to obtain a greater yield from the fishery is instructive. It is also worth noting that the substantial increase in the CPDF has been clearly beneficial to some fishermen.

12.4 Production Model Analysis

Production model analysis (Schaefer, 1954; Pella and Tomlinson, 1969) has been useful in describing the relationship between catch and effort during various phases of development of the yellowfin fishery. Initially, the 1934–55 catch and effort data for the near-shore baitboat fishery fitted the logistic, or symmetrical, form of the model quite well, and there was no reason to doubt its applicability at that time (Schaefer, 1957; 1967). One reason for the agreement may have been the effect of the baitboat fishery on stabilizing the age composition (Tomlinson, IATTC; pers. commun.), an assumption of the model and a necessary condition if it is to work. The apparent utility of the model was also supported by tagging results, which suggested a slow exchange rate between the near- and offshore areas, and by the impression that the catch and effort relationship was not masked by changes in environmental conditions. As a further sign of its usefulness, the model detected the first overfishing condition in the early 1960s. The decline in CPDF was attributed to the increase in effort, and particularly to that of the newly-introduced purse seiners. As the fishery rapidly expanded towards the outer boundary of the CYRA, and beyond it in 1968, it became apparent that the average maximum sustainable yield (AMSY) exceeded that predicted for the inshore area. A series of experiments was therefore undertaken to permit the use of successively larger quotas as a means of empirically determining the AMSY, while simultaneously monitoring the effect on the apparent abundance (Peterson and Bayliff, 1985). The experimental programme remained in effect until 1979.

The production model intentionally describes average conditions over the time series of the available data and it is insensitive to rapid, short-term changes in recruitment or age-specific mortality (IATTC, 1991a). In addition, the effect of changes in age composition on the yield are not incorporated into the model. Partly as a result of these limitations, the increasingly large catches of the mid 1980s, generated by the rising trends in recruitment and the capture of larger fish after 1982 (see above), began to exceed the AMSY considerably. The declines in stock size predicted by the model, however, did not materialize and contrasted with the opposite trends indicated by CPUE, cohort-biomass and yield-per-recruit analyses. To adjust for these imbalances, the stock size in 1985, a year in which all three indices were relatively large (Figure 14), was re-estimated by dividing the CPDF (for Class-6 purse seiners) by the catchability coefficient (q). Although the parameter estimates of the model were not particularly affected by this process, the 1987 biomass estimate increased substantially and the fishery was effectively divided into two time periods. The early portion corresponded to the interval 1968–1983 with q = 2.7 × 10-5 and an AMSY of 181 × 103 mt, and the late stage included 1984–1989 with q = 3.9 × 10-5 and AMSY = 298 × 103 mt. The general production models (Pella and Tomlinson, 1969) fitted to the catch and effort data for these two distinct phases (Figure 20, upper panel) are skewed to the left, as indicated by the shape parameter, m = 0.8. For the latest phase the distribution of points indicates that, with the current level of recruitment and concentration on larger fish, the fishery is operating in the optimum region of the AMSY. In relation to the observed CPDF, the values predicted by the model (Figure 20, lower panel) are smoothed by the averaging process. The differences between the two types of values in the late period are also exaggerated because the fit is based on only five data points.

Figure 20

Figure 20

Figure 20. Relationships between effort and catch for the yellowfin fishery in the eastern Pacific Ocean during 1968–89 for the generalized stock production (asymmetrical) model with m set at 0.8 (upper panel), and observed and predicted values of CPDF (lower panel). (Reproduced from IATTC, 1991a).

13. GEAR INTERACTIONS

The interaction between longline and purse-seine gears involving yellowfin in the EPO began to materialize through encounters in the early 1960s. Since then the subject has appeared in longline-fishery reviews of the region (Suda and Schaefer, 1965b; Kume and Schaefer, 1966; Kume and Joseph, 1969; Shingu et al., 1974; Miyabe and Bayliff, 1987), in population studies (Suzuki et al., 1978) and in exploratory analyses (Lenarz and Zweifel, 1979; Hilborn, 1989). The topic has also been reviewed by the IATTC (1987) and Suzuki (1988). A rather consistent theme throughout this literature is that the fish caught by longlines are almost entirely large, whereas the surface fleet captures smaller yellowfin. While this may be historically correct on average, the emergence of the purse seine as the dominant surface gear has modified this viewpoint. A more accurate description would be that both gears catch the same sizes of large fish, mostly between 90–150 cm, but additionally, because purse seines are more efficient, they also capture smaller fish in the 30–90 cm range. This overall range of sizes developed through evolution of the purse-seine fishery in seeking larger fish. In the process the tonnage caught by longlining in the EPO fell below that of purse seining in all size categories for the first time beginning in the early 1970s (Miyabe and Bayliff, 1987), and since then the quantity of longline-caught fish has declined progressively to a small fraction of that of the surface fleet (Table 4).

One of the topics examined by Lenarz and Zweifel (1979) was the effect on the Y/R of the degree of independence of stocks available to the longline and surface fisheries. Since no reliable information existed at the time on the simultaneous availability of yellowfin to both gears, they constructed stocks for each fishery based on the average size composition caught by the different gears in the eastern Atlantic during 1967–71 (Lenarz et al., 1974). The stocks also incorporated the sex ratios found in the central Pacific (Murphy and Shomura, 1972) for each gear type, and realistically portrayed the rapid decline in the proportion of females for fish larger than 135–140 cm. Simulation was then used to determine the effect of: 1) fishing a homogeneous stock by both gears, 2) allowing each gear type to fish a separate stock, and 3) allowing access of purse seiners to 50 percent of the longline stock. They drew several inferences from the study that were considered to be generally applicable. First, the portion of the longline catch that came from stock(s) exploited by the surface fishery did not have a significant effect on the relative values of Y/R within each hypothetical fishing situation. Consequently, “… decisions concerning minimum size regulations …” were not likely to be affected by the availability of stock(s) to the two fisheries. Second, the effect of one gear on the yield of the other was less pronounced for the realistic sex ratio than for the usual, 1:1 assumption. Finally, if the fish are equally available to both gears, the surface fishery depressed the Y/R of the longline gear to a greater extent than in the reverse situation, and the Y/R for combined gears was somewhat greater than the sum of each gear operating alone.

Hilborn (1989) reanalyzed the data used by Lenarz and Zweifel (1979) in the context of a spatially-structured population model in which the separate stocks fished by longlines and purse seiners were connected only by movements of individual fish. With constant recruitment, the Y/R analysis agreed with that of Lenarz and Zweifel (1979) in that the maximum amount was obtained when both fisheries were operating. In a stock-recruit situation, the total yield was still maximized by a combined fishery even though the overall yield was reduced for both gear types. Hilborn (1989) emphasized that the results were conditional upon the size distribution in the catch and the assumed growth curve. It should be mentioned that the data used in the above studies represents an historic situation because the catch in numbers for both gears were roughly the same. Today, as a consequence of mounting pressure from the purse-seine fleet, the longline catch in the eastern Atlantic and Pacific fisheries is about an order of magnitude less than that of purse seiners. Suzuki (1988) also pointed out that the study by Lenarz and Zweifel (1979) implied that the Y/R for both fisheries were about equal, and masked the impact of purse seining on the longline fishery. By assuming that in the eastern Atlantic the purse-seine and longline gears caught fish between 1–8 and 3–8 years, respectively, a Y/R analysis demonstrated that longlining was relatively much more sensitive to competition than purse seining.

Tagging results have indicated that there is a relatively low rate of mixing in an east-west direction within the EPO (Bayliff, 1979; 1984), and therefore it is reasonable to assume that the longline and purse-seine fisheries operate on the same stock. This has been difficult to demonstrate, however, given that depth appears to be the only major obstacle that separates the different gears. For example, tags from only six, large fish originally caught by surface gear have been returned by longline fishermen (IATTC, 1973, 1975, 1982), and one fish in the reverse direction (IATTC, 1982). In search of other linkages between the fisheries, Suzuki et al. (1978) noted that in the same area and similar period of time, female yellowfin caught by purse seines demonstrated a substantially higher degree of sexual maturity (gonad index) than those caught on longlines. Females captured by surface gear also displayed seasonal trends in reproductive activity in different size categories, a feature that was not as apparent for the longline-caught fish. Similar results were reported by Koido and Suzuki (1989), but for non-overlapping time periods. The amount of spatial overlap between the fisheries has also changed over time and obscured their relationship to a common stock. During 1971–80, for example, the longline fleet was largely absent from the region between 10°–20°N in the EPO, an area that was previously shared to a degree by both fisheries. At the same time, longlining operations expanded into the region of 20°–30°S, well beyond the southern limit of the purse-seine fishery.

Longline effort in the CYRA increased from 70 × 106 hooks during 1963–75 to 160 × 106 hooks in 1983 (Suzuki, 1988, Figure 30), but despite this substantial change the tonnage of yellowfin caught by this fishery has remained relatively stable since 1970 (Table 4, column 5). If the purse-seine and longline fisheries operate on the same stock, this stability is difficult to explain considering that over the same period the trends in the catch of the surface fleet reached high (288.2 × 103 mt) and low (94.1 × 103 mt) extremes (Table 4). In part, the stability may be due to the increased use of deep longlining and other selective practices to capture bigeye tuna, so that yellowfin has become an incidental catch. The fact that the longline yield of bigeye in the EPO has increasingly surpassed that of yellowfin since the early 1960s tends to support this view (IATTC, 1989). The stability may have also arisen from a dynamic balance achieved through increasing longline effort and the long-term effect of the purse-seine fishery's interception of a portion of the longline recruits. In this situation the change in the age composition of the longline catch would be reflected in a reduction in average weight, and indeed this quantity has gradually declined from approximately 59 kg (130 lb) during 1958–62 to 43 kg (95 lb) in 1967–80 (Miyabe and Bayliff, 1987). Further evidence that the two gear types act on the same stock is derived from a comparison of the CPUE of Class-6 seiners and longlines specifically for large fish (Figure 21, upper panel). The trends in these variables are visibly reinforced with appropriate scaling (Figure 21, lower panel) such that 73,800 hooks appear to be equivalent to one day of Class-6 effort (IATTC, 1987). In Section 11 it was mentioned that the escalation of effort and harvest of smaller fish by the purse-seine fleet during the 1970s and early 1980s eventually drove the biomass estimate to its lowest level in 1982. Since the CPUEs for both gear types paralleled each other during this period, and since the decline in abundance is reflected in the CPUE for the purse-seine fleet (Figure 14), there is little doubt of the impact that the purse-seine fishery has had on the longline catch.

Figure 21

Figure 21

Figure 21. CPUEs of large yellowfin by Class-6 purse seiners and by longliners, compared to biomass estimates of large yellowfin (upper panel); and catch per day's fishing by Class-6 purse seiners, compared to catch of yellowfin per 73,800 hooks by longliners (lower panel). All comparisons are for the eastern Pacific Ocean east of 150°W. (Reproduced from IATTC, 1987).

To help clarify the effect of the longline and purse-seine fisheries on each other and on the stock of yellowfin they exploit, research in a few key areas is needed. First, the timing and behavioural movement of fish from one fishery to the other will probably be best illuminated by tagging experiments. However, steps should be taken first to discover or circumvent the reasons why past experiments have produced such poor recovery rates. If tagged purse-seine- and longline-caught fish have little prospect of survival, the use of other gear, such as baitboats, to seek out and tag large yellowfin may be more successful. Since the two types of fisheries may interact in the Pacific, Atlantic and Indian Oceans, the location with the greatest potential for producing information should also be chosen. Second, the sex ratio and stages of female sexual maturity in the same time-area strata should be explored more fully in both fisheries. This is important for clarifying seasonal reproductive patterns and determining if changes in sex ratio are indicative of movement between the fishing zones. Third, an effort should be made to update and maintain a current position on the catch and CPUE of longline operations in the EPO. The information is needed to identify the response of the fishery relative to the increased recruitment and post-1983 recovery of the purse-seine fishery. The data are also necessary to monitor and detect changes or similarities in the CPUE between the two types of gear.

14. ACKNOWLEDGEMENTS

I would like to thank several members of the Commission's staff, and particularly Wm. Bayliff, R. Deriso and Pat. Tomlinson, for generously providing their time and counsel during the preparation of the manuscript.

15. REFERENCES CITED

Aikawa, H., and M. Kato. 1938. Age determination of fish-I [In Jpn.; Engl.summary]. Bull.Jap.Soc.Sci.Fish., 7(2):79–88. English translation In W G. Van Campen, 1950, Spec.Sci.Rep.U.S.Fish Wildl.Serv. (Fish.), (21):22 p.

Allen, R., and R. Punsly. 1984. Catch rates as indices of abundance of yellowfin tuna, Thunnus albacares, in the eastern Pacific Ocean. Bull. I-ATTC, 18(4):303–79.

Au, D.W.K., W.L. Perryman, and W.F. Perrin. 1979. Dolphin distribution and the relationship to environmental features in the eastern tropical Pacific. Admin.Rep.NMFS-SWFC La Jolla, LJ-79-43:59 p.

Bard, F.X. 1983. Croissance de l'albacore (Thunnus albacares) Atlantique, d'apres les donnes des marquages. Collect.Vol.Sci.Pap.ICCAT, 20(1):104–16.

Bard, F.X. 1984. Aspects de la croissance de l'albacore est Atlantique (Thunnus albacares) a partir des marquages. Collect.Vol.Sci.Pap.ICCAT, 21:108–14.

Barrett, I., and H. Tsuyuki. 1967. Serum transferrin polymorphism in some scombroid fishes. Copeia, (3):551–57.

Bayliff, W.H. 1971. Estimates of the rates of mortality of yellowfin tuna in the eastern Pacific Ocean derived from tagging experiments. Bull.I-ATTC, 15(4):379–436.

Bayliff, W.H. 1979. Migrations of yellowfin tuna in the eastern Pacific Ocean as determined from tagging experiments initiated during 1968–1974. Bull.I-ATTC, 17(6):447–506.

Bayliff, W.H. 1983. Analysis of population structure of fishes from life-history data. Collect.Vol.Sci.Pap.ICCAT, 18:776–91.

Bayliff, W.H. 1984. Migrations of yellowfin and skipjack tuna released in the central portion of the eastern Pacific Ocean, as determined by tagging experiments. Intern.Rep.IATTC, (18):107 p.

Bayliff, W.H. 1988. Growth of skipjack, Katsuwonus pelamis, and yellowfin, Thunnus albacares, tunas in the eastern Pacific Ocean, as estimated from tagging data. Bull.IATTC, 19(4):311–85.

Bayliff, W.H., and B.J. Rothschild. 1974. Migrations of yellowfin tuna tagged off the southern coast of Mexico in 1960 and 1969. Bull.I-ATTC, 16(1):1–64.

Bell, R.R. 1964. A history of tuna age determinations. Proc. Symp.Scombroid Fishes; J.Mar.Biol.Assoc.India, 2:693–706.

von Bertalanffy, L. 1938. A quantitative theory of organic growth. Hum.Biol., 10:181–213.

Blackburn, M. 1965. Oceanography and the ecology of tunas. Oceanogr. Mar.Biol.Ann.Rev., 3:299–322.

Blunt, C.E., Jr., and J.D. Messersmith. 1960. Tuna tagging in the eastern tropical Pacific, 1952–1959. Calif.Fish Game, 46(3):301–69

Broadhead, G.C. 1959. Morphometric comparisons among yellowfin tuna, Neothunnus macropterus, the eastern tropical Pacific Ocean. Bull.I-ATTC, 3(8):353–91.

Broadhead, G.C., and C.J. Orange. 1960. Species and size relationships within schools of yellowfin and skipjack tuna, as indicated by catches in the eastern tropical Pacific Ocean. Bull.I-ATTC, 4(7):449–92.

Brouard, F., R. Grandperrin and E. Cillaurren. 1984. Croissance des juenes thons jaunes (Thunnus albacares) et de bonites (Katuwonus pelamis) dans de Pacifique tropical occidental. [In Fr.; Engl. summary]. Doc.d'Ocean.ORSTOM Port-Vila, 10:23 p.

Buñag, D.M. 1956. Spawning habits of some Philippine tuna based on diameter measurements of the ovarian ova. J.Philipp.Fish., 4(2):145–77.

Bushnell, P.G., R.W. Brill and R.E.Bourke. 1990. Cardiorespiratory responses of skipjack tuna, Katsuwonus pelamis; yellowfin tuna, Thunnus albacares; and bigeye tuna, T. obesus, to acute reductions of ambient oxygen. Can.J.Zool.,: 1857–65.

Calkins, T.P. 1975. Geographical distribution of yellowfin and skipjack tuna catches in the eastern Pacific Ocean and total catch statistics, 1971–1974. Bull.I-ATTC, 17(1):1–116.

Calkins, T.P., and B.M. Chatwin. 1967. Geographical distribution of yellowfin tuna and skipjack catches in the eastern Pacific Ocean, by quarters of the year, 1963–1966. Bull.I-ATTC, 12(6): 433–508.

Calkins, T.P., and B.M. Chatwin. 1971. Geographical catch distribution of yellowfin and skipjack tuna in the eastern Pacific Ocean, 1967–1970, and fleet and total catch statistics, 1962–1970. Bull.I-ATTC, 15(3):283–377.

Carey, F.G., and R.J. Olson. 1982. Sonic tracking experiments with tunas. Coll.Vol. Sci.Pap.ICCAT, 17(2):458–66.

Chatwin, B.M. 1959. The relationships between length and weight of yellowfin tuna (Neothunnus macropterus) and skipjack tuna (Katsuwonus pelamis) from the eastern tropical Pacific ocean. Bull.I-ATTC, 3(7):307–52.

Cole, J.S. 1980. Synopsis of biological data on the yellowfin tuna, Thunnus albacares (Bonnaterre, 1788), in the Pacific Ocean. Spec.Rep.I-ATTC, (2):75–150.

Collette, B.B., and C.E. Nauen. 1983. FAO species catalogue. Vol. 2. Scombrids of the world. An annotated and illustrated catalogue of tunas, mackerels, bonitos and related species known to date. FAO Fish.Synop., 2(125):137 p.

Collette, B.B., T. Potthoff, W.J. Richards, S. Ueyanagi, J.L. Russo and Y. Nishikawa. 1984. Scombroidei: development and relationships. In Ontogony and systematics of fishes, edited by H.G. Moser. Spec.Publ.Am.Soc.Ichthyol.Herpetol., (1):591–620.

Davidoff, E.B. 1963. Size and year class composition of catch, age and growth of yellowfin tuna in the eastern tropical Pacific Ocean, 1951–1961. Bull.I-ATTC, 8(4):199–251.

Davis, T.L.O., G.P. Jenkins and J.W. Young. 1990. Diel patterns of vertical distribution in larvae of southern bluefin Thunnus maccoyii, and other tuna in the east Indian Ocean. Prog.Ser.Mar.Ecol., 59:63–74.

Díaz, E.L. 1963. An increment technique for estimating growth parameters of tropical tunas, as applied to yellowfin tuna (Thunnus albacares). Bull.I-ATTC, 8(7):381–416.

Draganik, B., and W. Pelczarski. 1984. Growth and age of bigeye and yellowfin tuna in the central Atlantic as per data gathered by R/V “Wieczno.” Collect.Vol.Sci.Pap.ICCAT, 20:96–103.

Fahay, M.P. 1983. Guide to the early stages of marine fishes occurring in the western North Atlantic Ocean, Cape Hatteras to the southern Scotian Shelf. J.Northwest.Atl.Fish.Sci., 423 p.

Fink, B.D., and W.H. Bayliff. 1970. Migrations of yellowfin and skipjack tuna in the eastern Pacific Ocean as determined by tagging experiments, 1952–1964. Bull.I-ATTC, 15(1):1–227.

Fishery Agency of Japan. 1974. Annual report of catch and effort statistics by area on Japanese longline fishery 1972. Annu.Rep.Effort Catch Stat.Area Jap.Tuna Longline Fish., (1972):279 p.

Fishery Agency of Japan. 1975. Annual report of catch and effort statistics by area on Japanese longline fishery 1973. Annu.Rep.Effort Catch Stat.Area Jap.Tuna Longline Fish., (1973):265 p.

Fishery Agency of Japan. 1976. Annual report of catch and effort statistics by area on Japanese longline fishery 1974. Annu.Rep.Effort Catch Stat.Area Jap.Tuna Longline Fish., (1974):267 p.

Fishery Agency of Japan. 1977. Annual report of catch and effort statistics by area on Japanese longline fishery 1975. Annu.Rep.Effort Catch Stat.Area Jap.Tuna Longline Fish., (1975):269 p.

Fonteneau, A. 1980. La croissance de l'albacore de l'Atlantique est. Collect.Vol.Sci. Pap.ICCAT, 9:152–68.

Francis, R.C. 1974. TUNPOP, a computer simulation model of the yellowfin tuna population and the surface tuna fishery of the eastern Pacific Ocean. Bull.I-ATTC, 16(3):233–79.

Francis, R.C. 1977. TUNPOP: a simulation of the dynamics and structure of the yellowfin tuna stock and surface fishery of the eastern Pacific Ocean. Bull.I-ATTC, 17(4):233–79.

Fujino, K. 1970. Immunological and biochemical genetics of tunas. Trans.Am.Fish. Soc., 99(1):152–78.

Fujino, K., and T. Kang. 1968a. Transferrin groups of tunas. Genetics, 59:79–91.

Fujino, K, and T. Kang. 1968b. Serum esterase groups of Pacific and Atlantic tunas. Copeia, (1):56–63.

Gibbs, R.H. Jr., and B.B. Collette. 1967. Comparative anatomy and systematics of the tunas, genus Thunnus. Fish.Bull.U.S.Fish Wildl.Serv., 66(1):65–130.

Godsil, H.C. 1948. A preliminary population study of the yellowfin tuna and the albacore. Fish Bull.Calif.Dep.Fish Game, (70):90 p.

Godsil, H.C., and E.E. Greenhood. 1951. A comparison of the populations of the yellowfin tuna, Neothunnus macropterus, from the eastern and central Pacific. Fish Bull.Calif.Dep.Fish Game, (82):33 p.

Graves. J.E., M.A. Samovich, and K.M. Schaefer. 1988. Electrophoretic identification of early juvenile yellowfin tuna, Thunnus albacares. Fish.Bull.NOAA-NMFS, 86(4):835–38.

Green, R.E. 1967. Relationships of the thermocline to success of purse seining for tuna. Trans.Am.Fish.Soc., 96(2):126–30.

Hammond, P.S. (editor). 1981. Report on the workshop on tuna-dolphin interactions. Spec.Rep.I-ATTC, 4:259 p.

Hanamoto, E. 1974. Fishery oceanography of bigeye tuna-I. La Mer (Bulletin de la Société Franco-Japonaise d'Océanographie), 12(3):128–36.

Harada, T., O. Murata, and S. Oda. 1980. Rearing of and morphological changes in larvae and juveniles of yellowfin tuna. Bull.Fac.Agric.Kinki Univ., (13):33–6.

Harada, T., K. Mizuno, O. Murata, S. Miyashita, and H. Furutani. 1971. On the artificial fertilization and rearing of larvae in yellowfin tuna. Bull.Fac.Agric.Kinki Univ., (4):145–51.

Hayashi, S. 1957. A review on age determination of the Pacific tunas. Indo-Pac. Fish.Coun., 7(II-III):53–64.

Hennemuth, R.C. 1961a. Size and year class composition of catch, age and growth of yellowfin tuna in the eastern tropical Pacific Ocean. Bull.I-ATTC, 5(1):1–112.

Hennemuth, R.C. 1961b. Year class abundance, mortality and yield-per-recruit of yellowfin in the eastern Pacific Ocean, 1954–1959. Bull.I-ATTC, 6(1):1–51.

Higgins, B.E. 1967. The distribution of juveniles of four species of tunas in the Pacific Ocean. Proc.Indo-Pac.Fish.Coun., 12(2):79–99.

Higgins, B.E. 1970. Juvenile tunas collected by midwater trawling in Hawaiian waters, July–September 1967. Trans.Am.Fish.Soc., 99(1):60–73.

Hilborn, R. 1989. Yield estimation for spatially connected populations: an example of surface and longline fisheries for yellowfin tuna. North Amer.J.Fish.Mgmt. 9(4):402–10.

Hisada, K. 1973. Investigation on tuna hand-line fishing ground and some biological observations on yellowfin and bigeye tunas in the northwestern Coral Sea. Bull.Far Seas Fish.Res.Lab., 8:35–69.

Holland, K.N., R.W. Brill and R.K.C. Chang. 1990. Horizontal and vertical movements of yellowfin and bigeye tuna associated with fish aggregating devices. Fish.Bull.NOAA-NMFS, 88(3):483–507.

Inter-American Tropical Tuna Commission. 1971. Annual report of the Inter-American Tropical Tuna Commission, 1970. Annu.Rep.I-ATTC, (1970):127 p.

Inter-American Tropical Tuna Commission. 1972. Annual report of the Inter-American Tropical Tuna Commission, 1971. Annu. Rep.I-ATTC, (1971): 129 p.

Inter-American Tropical Tuna Commission. 1973. Annual report of the Inter-American Tropical Tuna Commission, 1972. Annu. Rep.I-ATTC, (1972): 166 p.

Inter-American Tropical Tuna Commission. 1974. Annual report of the Inter-American Tropical Tuna Commission, 1973. Annu.Rep.I-ATTC, (1973): 150 p.

Inter-American Tropical Tuna Commission. 1975. Annual report of the Inter-American Tropical Tuna Commission, 1974. Annu.Rep.I-ATTC, (1974): 169 p.

Inter-American Tropical Tuna Commission. 1976. Annual report of the Inter-American Tropical Tuna Commission, 1975. Annu.Rep.I-ATTC, (1975): 176 p.

Inter-American Tropical Tuna Commission. 1977. Annual report of the Inter-American Tropical Tuna Commission, 1976. Annu.Rep.I-ATTC, (1976): 180 p.

Inter-American Tropical Tuna Commission. 1978. Annual report of the Inter-American Tropical Tuna Commission, 1977. Annu.Rep.I-ATTC, (1977): 155 p.

Inter-American Tropical Tuna Commission. 1979. Annual report of the Inter-American Tropical Tuna Commission, 1978. Annu.Rep.I-ATTC, (1978): 163 p.

Inter-American Tropical Tuna Commission. 1980. Annual report of the Inter-American Tropical Tuna Commission, 1979. Annu.Rep.I-ATTC, (1979): 227 p.

Inter-American Tropical Tuna Commission. 1981. Annual report of the Inter-American Tropical Tuna Commission, 1980. Annu.Rep.I-ATTC, (1980): 234 p.

Inter-American Tropical Tuna Commission. 1982. Annual report of the Inter-American Tropical Tuna Commission, 1981. Annu.Rep.I-ATTC, (1981):303 p.

Inter-American Tropical Tuna Commission. 1983. Annual report of the Inter-American Tropical Tuna Commission, 1982. Annu.Rep.I-ATTC, (1982): 272 p.

Inter-American Tropical Tuna Commission. 1984. Annual report of the Inter-American Tropical Tuna Commission, 1983. Annu.Rep.I-ATTC, (1983): 272 p.

Inter-American Tropical Tuna Commission. 1987. Annual report of the Inter-American Tropical Tuna Commission, 1986. Annu.Rep.I-ATTC, (1986): 264 p.

Inter-American Tropical Tuna Commission. 1988. Annual report of the Inter-American Tropical Tuna Commission, 1987. Annu.Rep.I-ATTC, (1987): 222 p.

Inter-American Tropical Tuna Commission. 1989. Annual report of the Inter-American Tropical Tuna Commission, 1988. Annu.Rep.I-ATTC, (1988): 288 p.

Inter-American Tropical Tuna Commission. 1990. Quarterly report of the Inter-American Tropical Tuna Commission. Quart.Rep.I-ATTC, 2:5–6.

Inter-American Tropical Tuna Commission. 1991a. Annual report of the Inter-American Tropical Tuna Commission, 1989. Annu. Rep.I-ATTC, (1989): 270 p.

Inter-American Tropical Tuna Commission. 1991b. Quarterly report of the Inter-American Tropical Tuna Commission. Quart.Rep.I-ATTC, 2:(in press).

Joseph, J. 1963. The fecundity of yellowfin tuna (Thunnus albacares) and skipjack (Katsuwonus pelamis) from the eastern Pacific Ocean. Bull.I-ATTC, 7(4):255–92.

Joseph, J., and F.R. Miller, 1988. El Ni±o and the surface fishery for tunas in the eastern Pacific. In Proceedings of the Tuna Fishery Research Conference, Far Seas Fish.Res.Lab. Maguro Gyogyo Kyogikai Gijiroku, Suisancho-Enyo Suisan Kenkyusho: 199–207.

Joseph, J., F.G. Alverson, B.D. Fink, and E.B. Davidoff. 1964. A review of the population structure of yellowfin tuna, Thunnus albacares, in the eastern Pacific Ocean. Bull.I-ATTC, 9(2):53–112.

June, F.C. 1953. Spawning of yellowfin tuna in Hawaiian waters. Fish.Bull.U.S.Fish Wildl.Serv., 54(77):47–64.

Kamimura, T., and M. Honma. 1963. Distribution of the yellowfin tuna Neothunnus macropterus (Temminck and Schlegel) in the tuna longline fishing grounds of the Pacific Ocean. FAO Fish.Rep., 6(3):1299–328.

Kikawa, S. 1959. Notes on the regional difference of spawning season of Pacific yellowfin tuna. Rep.Nankai Reg.Fish.Res.Lab., (11):59–76.

Kikawa, S. 1962. Studies on the spawning activity of Pacific tunas, Parathunnus mebachi and Neothunnus macropterus, by the gonad index examination. Rep.Nankai Reg.Fish.Res.Lab., (1):43–56.

Kikawa, S. 1966. The distribution of maturing bigeye and yellowfin and an evaluation of their spawning potential in different areas in the tuna longline grounds in the Pacific. Rep.Nankai Reg.Fish.Res.Lab., (23):131–208.

Klawe, W.L. 1963. Observations on the spawning of four species of tuna, Neothunnus macropterus, Katsuwonus pelamis, Auxis thazard, and Euthynnus lineatus, in the eastern Pacific Ocean, based on the distribution of their larvae and juveniles. Bull.I-ATTC, 6(9):447–540.

Klawe, W.L. 1980. Classification of tunas, mackerels, billfishes, and related species and their geographical distribution. Spec.Rep.I-ATTC, (2):7–16.

Klawe, W.L., J.J. Pella, and W.S. Leet. 1970. The distribution, abundance and ecology of larval tunas from the entrance to the Gulf of California. Bull.I-ATTC, 14(4):505–44.

Knudsen, P.F. 1977. Spawning of yellowfin tuna and the discrimination of subpopulations. Bull.I-ATTC, 17(2):117–69.

Koido, T.V., and Z. Suzuki. 1989. Main spawning of yellowfin, Thunnus albacares, in the western tropical Pacific Ocean based on the gonad index. Bull.Far Seas Fish.Res.Lab., (26):153–63.

Kume, S., and J. Joseph. 1969. The Japanese longline fishery for tunas and billfish in the eastern Pacific Ocean east of 130°W, 1964–1966. Bull.I-ATTC, 13(2):275–418.

Kume, S., and M.B. Schaefer. 1966. Studies of the Japanese long-line fishery for tuna and marlin in the eastern tropical Pacific Ocean during 1963. Bull.I-ATTC, 11(3):101–70.

Kurogane, K., and Y. Hiyama. 1957. Morphometric comparison of the yellowfin taken from the equatorial Pacific. Bull.Jap.Soc.Sci.Fish., 23(7–8):388–93.

Le Guen, J.C., and G.T. Sakagawa. 1973. Apparent growth of yellowfin tuna from the eastern Atlantic Ocean. Fish.Bull.NOAA-NMFS, 71(1):175–87.

Legand, M. 1960. Longuer, repartition des sexes et maturation sexuelle des thons a nageoires jaunes de Nouvelle-Caledonie. Rapp.Sci.ORSTOM Nouvelle-Caledonie, (11):6–20.

Lenarz, W.H., and J.R. Zweifel. 1979. A theoretical examination of some aspects of the interaction between longline and surface fisheries for yellowfin tuna, Thunnus albacares. Fish.Bull.NOAA-NMFS, 76(4):807–25.

Lenarz, W.H., W.W. Fox, Jr., G.T.Sakagawa, and B.J. Rothschild. 1974. An examination of the yield per recruit basis for a minimum size regulation for Atlantic yellowfin tuna, Thunnus albacares. Fish.Bull.NOAA-NMFS, 72(1):37–61.

Lindberg, G.U. 1971. Fishes of the world. A key to families and a checklist. New York, John Wiley and Sons, 545 p.

Marsac, F., and G. Lablanche. 1985. Preliminary study of the growth of yellowfin (Thunnus albacares) estimated from purse seine data in the western Indian Ocean. In Expert Consultation on the Stock Assessment of Tunas in the Indian Ocean, Nov. 28–Dec.2, 1985. Indo-Pac.Tuna Dev.Mgmt.Programme, Doc. 31:13 p.

Matsumoto, W.M. 1958. Description and distribution of larvae of four species of tuna in central Pacific waters. Fish.Bull.U.S.Fish Wild.Serv., 58(128):31–72.

Matsumoto, W.M. 1961. Collections and descriptions of juvenile tunas from the central Pacific. Deep-Sea Res., 8(3–4):279–86.

Matsumoto, W.M. 1962. Identification of larvae of four species of tuna from the Indo-Pacific region I. Dana Report, 55:16 p.

Matsumoto, W.M. 1966. Distribution and abundance of tuna larvae in the Pacific Ocean. In Proceedings of the Governor's Conference on Central Pacific Fishery Resources, edited by T.A. Manar, :221–30.

Matsumoto, W.M., E.H. Ahlstrom, S. Jones, W.L. Klawe, W.J. Richards, and S. Ueyanagi. 1972. On the clarification of larval tuna identification particularly the genus Thunnus. Fish.Bull.NOAA-NMFS, 70(1):1–12.

McNeeley, R.L. 1961. The purse seine revolution in tuna fishing. Pac.Fish., 59(7):27–58.

Mead, G.M. 1951. Postlarval Neothunnus macropterus, Auxis thazard, and Euthynnus lineatus from the Pacific coast of Central America. Fish.Bull.U.S.Fish Wildl.Serv., 52(63):121–27.

Miller, F.R., and R.M. Laurs. 1975. The El Niño of 1972–1973 in the eastern tropical Pacific Ocean. Bull.I-ATTC, 16(5):403–48.

Miyabe, N., and W.H. Bayliff. 1987. A review of the Japanese longline fishery for tunas and billfishes in the eastern Pacific Ocean, 1971–1980. Bull.I-ATTC, 19(1):1–163.

Moore, H.L. 1951. Estimation of age and growth of yellowfin tuna (Neothunnus macropterus) in Hawaiian waters by size frequencies. Fish.Bull.U.S.Fish Wildl.Serv., 52(65):132–49.

Mori, K. 1970. A consideration on the spawning of the tunas, especially of the yellowfin tuna (Thunnus albacares) in the adjacent sea of the Pacific coast of Japan. Bull.Far Seas Fish.Res.Lab., (3):215–28.

Mori, K., S. Ueyanagi, and Y. Nishigawa. 1971. The development of artificially fertilized reared larvae of the yellowfin tuna, Thunnus albacares. [In Jpn.; Engl. synop.]. Bull.Far Seas Fish.Res.Lab., (5):219–32.

Murphy, G.I, and R.S. Shomura. 1972. Pre-exploitation abundance of tunas in the equatorial central Pacific. Fish.Bull.U.S.Fish Wildl.Serv., (70):875–913.

Murphy, T.C., and G.T. Sakagawa. 1977. A review and evaluation of estimates of natural mortality rates of tunas. Collect.Vol.Sci.Pap.ICCAT, 6(1):117–23.

Nakamura, E.L., and W.M. Matsumoto. 1967. Distributions of larval tunas in Marquesan waters. Fish.Bull.U.S.Fish Wildl.Serv., 66(1):1–12.

Nakamura, E.L., and J.H. Uchiyama. 1966. Length weight relations of Pacific tunas. In Proceedings of the Governor's Conference on Central Pacific Fishery Resources, Hawaii, : 197–201.

Nishikawa, Y., and D.R. Rimmer. 1987. Identification of larval tunas, billfishes, and other scombroid fishes (Suborder Scombroidei): an illustrated guide. CSIRO Rep.Aust., (186):20 p.

Nishikawa, Y., M. Honma, S. Ueyanagi, and S. Kikawa. 1985. Average distribution of larvae of oceanic species of scombroid fishes, 1956–1981. S Ser.Far Seas Fish.Res.Lab., (12):99 p.

Nose, Y., H. Kawatsu, and Y. Hiyama. 1957. Age and growth of Pacific tunas by scale reading [In Jpn.; Engl. summary]. Suisan Gaku Shusei, Tokyo University Press, pp. 701–16.

Orange, C.J. 1961. Spawning of yellowfin tuna and skipjack in the eastern tropical Pacific, as inferred from studies of gonad development. Bull.I-ATTC, 5(6):457–526.

Orange, C.J., M.B. Schaefer, and F.M. Larmie. 1957. Schooling habits of yellowfin tuna (Neothunnus macropterus) and skipjack (Katsuwonus pelamis) in the eastern Pacific ocean as indicated by purse seine catch records, 1946–1955. Bull.I-ATTC, 2(3):83–126.

Pella, J.J., and C.T. Psaropulos. 1975. Measures of tuna abundance from purse-seine operations in the eastern Pacific Ocean adjusted for fleet-wide evolution of increased fishing power, 1960–1971. Bull.I-ATTC, 16(4):283–400.

Pella, J.J., and P.K. Tomlinson. 1969. A generalized stock production model. Bull.IATTC, 13(3):421–96.

Perrin, W.F. 1969. Using porpoise to catch tuna. World Fishing, 18(6):42–5.

Perrin, W.F., R.R. Warner, C.H. Fiscus, and D.B. Holts. 1973. Stomach contents of porpoise, Stenella spp., and yellowfin tuna, Thunnus albacares, in mixed-species aggregations. Fish.Bull.NOAA-NMFS, 71(4):1077–92.

Peterson, C.L. and W.H. Bayliff. 1985. Organization, functions, and achievements of the Inter-American Tropical Tuna Commission. Spec.Rep.I-ATTC, (5):56 p.

Philander, S.G. 1990. El Niño, La Niña, and the Southern Oscillation. Vol. 46, Ser.Internat.Geophys., Academic Press, 293 p.

Pickard, G.L. 1968. Descriptive Physical Oceanography. London, Permagon Press, 200 p.

Punsly, R. 1987. Estimation of the relative annual abundance of yellowfin tuna, Thunnus albacares, in the eastern Pacific Ocean during 1970–1985. Bull.I-ATTC, 19(3):265–306.

Richards, F.J. 1959. A flexible growth function for empirical use. J.Exp.Bot., 10(29):290–300.

Richards, W.J. 1989. Preliminary guide to the identification of early life history stages of scombroid fishes of the western central Atlantic. NOAA Tech.Memo.NMFS-SWFC, La Jolla, (240):101 p.

Richards, F.J., and G.R. Dove. 1971. Internal development of young tunas of the genera Katsuwonus, Euthynnus, Auxis and Thunnus (Pisces, Scomberidae). Copeia, (1):72–8.

Richards, F.J., and D.C. Simmons. 1971. Distribution of tuna larvae (Pisces, Scombridae) in the northwestern Gulf of Guinea and off Sierra Leone. Fish.Bull.NOAA-NMFS, 69(3):555–68.

Richards, F.J., T. Potthoff, and J.-M. Kim. 1990. Problems identifying tuna larvae species (Pisces: Scombridae: Thunnus) from the Gulf of Mexico. Fish.Bull.NOAA-NMFS, 88(3): 607–609.

Ricker, W.E. 1979. Growth rates and models. In Fish Physiology, edited by S. Hoar, D.J. Randall and J.R. Brett, Vol. 8., New York, Academic Press, 786 p.

Rosa, H., Jr. 1950. Scientific and common names applied to tunas, mackerels and spearfishes of the world with notes on their geographical distribution. Washington, FAO, 235 p.

Royce, W.F. 1953. Preliminary report on a comparison of the stocks of yellowfin tuna. Proc.Indo-Pac.Fish.Coun., 4(2):130–45.

Royce, W.F. 1964. A morphometric study of yellowfin tuna Thunnus albacares (Bonnaterre). Fish.Bull.U.S.Fish Wildl.Serv., 63(2):395–443.

Schaefer, K.M. 1987. Reproductive biology of black skipjack, Euthynnus lineatus, an eastern Pacific tuna. Bull.I-ATTC, 19(2):169–260.

Schaefer, K.M. 1988. Time and frequency of spawning of yellowfin tuna at Clipperton Island, and plans for future studies. In Proceedings of Tuna Fishery Research Conference, Far Seas Fishery Research Laboratory. Maguro Giyiroku, Suisancho-Enyo Suisan Kendyusho, :118–26.

Schaefer, K.M. 1989. Morphometric analysis of yellowfin tuna, Thunnus albacares, from the eastern Pacific Ocean. Bull.I-ATTC, 19(5):389–427.

Schaefer, K.M. 1991. Geographic variation in morphometric characters and gill-raker counts of yellowfin tuna Thunnus albacares from the Pacific Ocean. Fish.Bull.NOAA-NMFS, 89(2):289–97.

Schaefer, M.B. 1952. A comparison of yellowfin tuna of Hawaiian waters and of the American west coast. Fish.Bull.U.S.Fish Wildl.Serv., 52(72):353–73.

Schaefer, M.B. 1954. Some aspects of the dynamics of populations important to the management of the commercial marine fisheries. Bull.I-ATTC, 1(2):27–56.

Schaefer, M.B. 1955. Morphometrics comparison of yellowfin tuna from southeast Polynesia, Central America and Hawaii. Bull.I-ATTC, 1(4):89–136.

Schaefer, M.B. 1957. A study of the dynamics of the fishery for yellowfin tuna in the eastern tropical Pacific Ocean. Bull.I-ATTC, 2(6):245–85.

Schaefer, M.B. 1967. Fishery dynamics and present status of the yellowfin tuna population of the eastern Pacific Ocean. Bull.I-ATTC, 12(3):87–136.

Schaefer, M.B., and J.C. Marr. 1948. Juvenile Euthynnus lineatus and Auxis thazard from the Pacific Ocean and Central America. Pac.Sci., 2(4):262–71.

Schaefer, M.B., B.M. Chatwin, and G.C. Broadhead. 1961. Tagging and recovery of tropical tunas, 1955–1959. Bull.I-ATTC, 5(5):341–455.

Sharp, G.D., and S. Pirages. 1978. The distribution of red and white swimming muscles, their biochemistry, and the biochemical phylogeny of selected scombrid fishes. In The physiological ecology of tunas, edited by G.D. Sharp and A.E. Dizon. New York, Academic Press, 485 p.

Shimada, B.M. 1951. Contributions to the biology of tunas from the western equatorial Pacific. Fish.Bull.U.S.Fish Wildl.Serv., 52(62):111–9.

Shingu, C., P.K. Tomlinson, and C.L. Peterson. 1974. A review of the Japanese longline fishery for tunas and billfishes in the eastern Pacific Ocean, 1967–1970. Bull.I-ATTC, 16(2):65–230.

Shomura, R.S. 1966. Age and growth studies of four species of tunas in the Pacific Ocean. In Proceedings of the Governor's Conference on Central Pacific Fishery Resources, edited by T.A. Manar. Hawaii, pp. 203–219.

Sprague, L.M. 1967. Multiple molecular forms of serum esterase in three tuna species from the Pacific Ocean. Hereditas, 57:198–204.

Strasburg, D.W. 1960. Estimates of larval tuna abundance in the central Pacific. Fish.Bull.U.S.Fish Wildl.Serv., 60(167):231–55.

Suda, A., and M.B. Schaefer. 1965a. Size-composition of catches of yellowfin in the Japanese long-line fishery in the eastern tropical Pacific east of 130°W. Bull.I-ATTC, 10(4):267–331.

Suda, A., and M.B. Schaefer. 1965b. General review of the Japanese tuna long-line fishery in the eastern tropical Pacific Ocean 1956–1962. Bull.I-ATTC, 9(6):307–462.

Sun', Tszi-Dzen'. 1960. Lichiniki i mal'ki tuntsov, parunsnikov i mech-ruby (Thunnidae, Istiophoridae, Xiphiidae) tsentral 'noi i zapadnoi chasti Tikhogo okeana (Larvae and juveniles of tunas, sailfishes and swordfish (Thunnidae, Istiophoridae, Xiphiidae) from the central and western part of the Pacific Ocean. Trudy Inst.Okeanol., 41:175–91.

Sund, P.N., M. Blackburn, and F. Williams. 1981. Tunas and their environment in the Pacific Ocean: a review. Oceanogr.Mar.Biol.Ann.Rev., 19:443–512.

Suzuki, A. 1962. On the blood types of yellowfin and bigeye. Amer.Natur., 96(889):239–46.

Suzuki, Z. 1971. Comparison of growth parameters estimated for the yellowfin tuna in the Pacific Ocean [In Jpn.; Engl. synopsis]. Bull.Far Seas Fish.Res.Lab., (5):89–105.

Suzuki, Z. 1974. Re-examination of scale reading method of yellowfin tuna taken in the western and central Pacific Ocean. [In Jpn.; Engl. synopsis]. Bull.Far Seas Fish.Res.Lab., (5):89–105.

Suzuki, Z. 1988. Study of interaction between longline and purse seine fisheries on yellowfin tuna, Thunnus albacares (Bonnaterre). Bull.Far Seas Fish.Res.Lab., (25):73–143.

Suzuki, Z., P.K. Tomlinson, and M. Honma. 1978. Population structure of Pacific yellowfin tuna. Bull.I-ATTC, 17(5):273–441.

Suzuki, Z., Y. Warashina, and M. Kishida. 1977. The comparison of catches by regular and deep tuna longline gears in the western and central equatorial Pacific. Bull.Far Seas Fish.Res.Lab., (15):51–73.

Uchiyama, J.H., and P. Struhsaker. 1981. Age and growth of skipjack tuna, Katsuwonus pelamis, and yellowfin tuna, Thunnus albacares, as indicated by daily growth increments of sagittae. Fish.Bull.NOAA-NMFS, 79(1):151–62.

Ueyanagi, S. 1966. On the pigmentation of larval tuna and its usefulness in species identification. Rep.Nankai Reg.Fish.Res.Lab., (24):41–8.

Ueyanagi, S. 1969. Observations on the distribution of tuna larvae in the Indo-Pacific Ocean with emphasis on the delineation of the spawning areas of albacore, Thunnus alalunga. Bull.Far Seas Fish.Res.Lab., (2):177–256.

Ueyanagi, S. 1978. Recent tuna culture research in Japan. Paper presented at the International Ocean Development Conference, 5(C1):23–39 (preprint).

Ueyanagi, S., K. Mori, and Y. Nishikawa. 1969. Research on distribution of larvae. S Ser.Far Seas Fish.Res.Lab., (1):12–7.

U.S. Dept. of Commerce. 1977. Administration of the Marine Mammal Protection Act of 1972. NOAA-NMFS. Reprinted from Fed. Register, 42(147):38982–9030.

U.S. Dept. of Commerce. 1978. The Marine Mammal Protection Act of 1972. Annual Rep., April 1, 1977, to March 31, 1978 : 202 p.

de Vlaming, V.L. 1982. On the use of the gonosomatic index. Comp.Biochem.Physiol., 73A (1):31–9.

Wade, C.B. 1950a. Juvenile forms of Neothunnus macropterus, Katsuwonus pelamis and Euthynnus yaito from Philippine seas. Fish.Bull.U.S.Fish Wildl.Serv., 51(53):395–404.

Wade, C.B. 1950b. Observations on the spawning of Philippine tuna. Fish.Bull.U.S. Fish Wildl.Serv., 51(55):409–23.

Wade, C.B. 1951. Larvae of tuna and tuna-like fishes from Philippine waters. Fish. Bull.U.S.Fish Wildl.Serv., 51(57):445–85.

Wankowski, J.W.J. 1981. Estimated growth of surface-schooling skipjack tuna, Katsuwonus pelamis, and yellowfin tuna, Thunnus albacares, from the Papua New Guinea region. Fish.Bull.NOAA-NMFS, 79(3):517–45.

Wild, A. 1986. Growth of yellowfin tuna, Thunnus albacares, in the eastern Pacific Ocean based on otolith increments. Bull.I-ATTC, 18(6):423–82.

Wild, A., and T.J. Foreman. 1980. The relationship between otolith increments and time for yellowfin and skipjack tunas marked with tetracycline. Bull.I-ATTC, 17(7):507–60.

Wyrtki, K., and B. Kilonsky. 1984. Mean water and current structure during the Hawaii-to-Tahiti shuttle experiment. J.Phys.Oceanogr., 14:242–54.

Yabe, H., and S. Ueyanagi. 1962. Contributions to the study of the early life history of tunas. Occas.Rep.Nankai Reg.Fish.Res.Lab., (1):57–72.

Yabe, H., N. Anraku, and M. Yukinawa. 1958. Studies on the yellowfin tuna-III. Annual variations of the size composition and the hooked-rates of yellowfin tuna distributing in the equatorial Pacific. Rep.Nankai Reg.Fish.Res.Lab., (7):88–104.

Yabe, H., Y. Yabuta, and S. Ueyanagi. 1963. Comparative distribution of eggs, larvae, and adults in relation to biotic and abiotic environmental factors. FAO Fish.Rep., 6(3):979–1,009.

Yabe, H., S. Ueyanagi, S. Kikawa, and H. Watanabe. 1958. Young tunas found in the stomach contents. Rep.Nankai Reg.Fish.Res.Lab., (8):31–48.

Yabuta, Y., M. Yukinawa, and Y. Warashina. 1960. Growth and age of yellowfin tuna II. Age determination (scale method). [In Jpn.; Engl. summary]. Rep.Nankai Reg.Fish.Res.Lab., (12):63–74.

Yamanaka, K.L. 1990. Age, growth and spawning of yellowfin tuna in the southern Philippines. Colombo, Sri lanka, Indo-Pac.Tuna Dev.Mgt.Programme, IPTP/90/WP/21:87 p.

Yang, R-T. 1971. Population study of yellowfin tuna in the waters adjacent to Taiwan. Nat.Taiwan Univ.Sci.Rep.Acta Oceanogr.Taiwanica, (1):137–55.

Yang, R-T., Y. Nose, and Y. Hiyama. 1969. A comparative study on the growth of yellowfin tunas from the Atlantic and Pacific Oceans. Bull.Far Seas Fish.Res.Lab., (2):1–21.

Yuen, H.S.H. 1963. Schooling behavior within aggregations composed of yellowfin and skipjack tuna. FAO Fish.Rep., 6(3):1419–29.

Yuen, H.S.H., and F.C. June. 1957. Yellowfin tuna spawning in the central equatorial Pacific. Fish.Bull.U.S.Fish Wildl.Serv., 57(112):251–64.


Previous Page Top of Page Next Page