UNITED STATES DEPARTMENT OF THE INTERIOR, OSCAR L. CHAPMAN, Secretary FISH AND WILDLIFE SERVICE, ALBERT M. DAY, Director

OBSERVATIONS ON THE SPAWNING OF PHILIPPINE TUNA

By CHARLES B. WADE, Aquatic Biologist

FISHERY BULLETIN 55 From Fishery Bulletin: of the Fish and Wildlife Service VOLUME 51

UNITED STATES GOVERNMENT PRINTING OFFICE WASHINGTON : 1950

For sale by the Superintendent of Documents, U. S. Government Printin~ Office, Washington 25, D. C. Price 15 cents CONTENTS Page Classification of gonads- 409

Euthynnus yaito (Kishinouye) 410

Katsuwonus pelamis (Linnaeus) 411

N eot/mnllus macropterliS (Temminck and Schlegel)______415 Summary . .______423

Literature cited __ .. . .______423

II QBSERVATIO~S ON THE SPAwNING. OF PHILIPPINE. 'ruN-A..

By CHARLES B. WADE, Aquatic Biologist

The study of the life histories of the several com­ criteria described by Marr (1948); .' To the stages of mercially important species of tuna in the Pacific gonad development as classified by him. immature, Ocean has been greatly accelerated by the postwar ripening, ripe, spawning, and spent, was added 'the expansion .of the tuna fishery in that area. One term "unknown" for those fish in which the gonads phase of their life histories that has aroused con­ were insufficiently developed to determine the. sex, siderable interest· and speculation, both scientific or the degree of maturity was not noted 'for some and popular; concerns the time and place of spawning. reason. Some research has been done on this in the Mediter­ Marr (1948) suggested that after the fish spawn ranean area, and although incomplete, much has for the first time the gonads do not. reduce to the been learned of the early life history of the tuna of small size prevailing before first maturity.. The' size that region. In the Pacific, on the other hand, of the gonads during the so-called "resting, stage" almost nothing was known of their spawning habits between spawning periods is not known. It is .im­ until Schaefer and Marr (1948) and Marr (1948) possible at the present time to distinguish externally published a series of short papers on the spawning between gonads ripening for the first time and those and juvenile forms of the genera Neothunnus, Kat­ that are reduced .in .size after spawning. At some suwonus, Euthynnus, and A1txis. They demon­ time during the spawning cycle. the two stage's 'could strated; by the collection of juveniles, that these presumably appear identical. There seems:to be no four genera spawn along the west coast of Central doubt that a certain percentage of fish designated America and that the genus Katsuwonus also spawns as ripening in the present' study were iIi' this ~esti~g in the northern Marshall Islands. stage. In the pelagic fish studies of the Philippine Fishery Although this classification gives a good estimate Program 1 of the Fish and Wildlife Service informa­ of the gross changes that occur during the maturation tion on all phases of the biology of the Philippine of the gonads, it is not sufficiently precise to evaluate tuna has been sought since October 1947. One part properly the gonad condition in a more comprehen~ of this operation has been concerned with the accu­ sive study. It has been the experience of biologists mulation of data on the degree of maturity of the of the Philippine Fishery Program that the external fish caught and the search for juvenile forms. The . appearance of the gonads is often deceiving and con~ data were collected on the oceanographic research siderable experience is required to classify these vessel, Spmcer F. Baird, from fish caught principally organs correctly. by trolling during the period October 1947 through Many factors contribute to the variations in the' November 1948. external appearance of the gonads that might in~ fluence the judgment of the observer. Among these: CLASSIFICATION OF GONADS are the size of .the specimen, the number of times it . Determinations of the degree of maturity were had spawned, ';'ariations in' size and appearance ot made as the fish were captured,in accordance with the gonads of seemingly identical specimens, the physi­ cal condition of, the 'fish; and there-~lfe;-' no 'doubt~ lA part of the Philippine Rehabilitation Program authorized by the Philippine Rehabilitation Act of 1946. title SO. App. U. S. Code. Sec. 1789. other factors. The development of a method of ac- '469 410 FISHERY BULLETIN OF THE. FISH .&ND WILDLIFE SERVICE curately evaluating the gonad condition will require Ripening fish of both sexes and in all stages of considerable research. It appears that the ovary, ripening were captured throughout the year. This rather than the testes, offers the more satisfactory suggests that spawning is not confined to any par­ means of establishing an index to maturity. It may ticular period. Also, based on the size range of be that after considerable study of the maturation ripening and .ripe specimens in the collections, it is of the eggs in the ovary," a reference point can be evident that E. yaito begins to ripen at a smaller located from which small identical samples may be size' than this sample of ripening fish would indicate. taken. The diameters of the eggs in the sample The difficulty of distinguishing ripe from spent could then be tabulated and it may be found that males has, undoubtedly, introduced some degree of combinations of certain percentages of various size error in the number of ripe males reported. The classes will provide a formula for determining more tendency has been to classify males as ripe rather accurately the various degrees of maturity. than spent. On the other hand, no error of this nature should occur with the females. Consider­ ..EUTHYNNUS YAITO (KISHINOUYE) able range in the' size of ripe gonads' wa.s noted not The field data for this species are presented in only throughout the size range, but among indi­ tables 1, 2, and 3 and figure 1. viduals of similar size. Immature fish were captured only from March Spawning and spent fish were taken throughout through July. The immature females averaged the period of operation. No .running-ripe females larger .than the males, which may have been the were seen although specimens were secured in which result of an inadequate sample. Again, it may the eggs were lying free in the posterior part of the indicate that the females grow more rapidly or reach ovary. Spawning males were common, ·however, maturity at a greater age and a larger size, than the often extruding milt on the deck when brought males, if the growth rate of the two sexes is equal. aboard ship. In addition to the immature fish of which the sex There is only one specific reference to the spawning could be determined, specimens were taken of which of E. yaito in the literature. Kishinouye (1923) the sex could not be identified by field methods. stated that spawning takes place in Taiwan (For­ The gonads of these fish were elongate, thread-like mosa) about May. This observation was based bodies barely visible in the enveloping membrane on a single 115 mm. specimen collected from that and in all cases the weight of the gonads and attached area during the latter part of August. Schaefer membranes was less than 1 gram. and Marr (1948) collected a running-ripe female of

II

14 LENGTH FREQUENCY Euthynnus yo ito

10 ! ­o '8 ~

I>• E '1 iI

e

•

300 no 400 450 . 500 550 &\10 &50 70 Length' in millimeters FIGURE 1.-Length-frequency distribution of Euthynnus yaito taken in Philippine waters from October 1947 through November 1948. SPAWNING OF PHILIPPINE TUNA 411 a closely related species, Euthynnus lineattlS, off the· TABLE I.-Mollthly Jummary of all Jpecimem of Euthynnus yaito taken by the Spencer F. Baird, October 1947-NorJember 1948"':""Con. Cen~ral west. coast of America in AprjI. . . ." The presence of fish in all stages of sexual develop­ ment· during the entire· year in Philippine waters seems indicative of year-round spawning in that ALL FISH-Continued area. Although its is certain .that spawning does JUly ] 2 1 5 6 • "_ 18 occur throughout the year, the sample is not suffi­ ~~~~b-;,~:::::::::::: ~_ ~ ciently large to determine possible seasonal varia­ October ,______:::::: ::::::1 1::::::.:: 5:::::: 7 ::::::: 1. November . f6 9 23 8 I. 87 tions in intensity during that time. Total. __ --19 ------97 88 137 ---95 ------2f f60 KATSUWONUS PELAMIS (LINNAEUS) MALES The data for KatsuflJOllllS pelamis are presented October _ in tables .4, 5, and 6 ·and figure 2. November _ December______3 1 15· __ ~ ~ __ ~___ 19 . Only an occasional immature fish was taken dur­ January______1 4 16 ~ ~~_ 21- February______25 23 6 ,-__-_... -I 55 ing the· entire period of operations. The poor March ~__ I 3 • ~epresentation of small, imma·ture fish of all species in the collections c;:an be explained partly by the ~i~m~m~m~m ::::~: ~m~~ ~.~~~~~~ il_ fact that the trolling ·gear was designed primarily :::I .t _" t ._ . b~~~:'~e::::::::::::: :::::: :::::: :::::: ------.5" ---T ::::::: -----9 for larger fish and, consequently, smaller specimens November______18 5 23 3 .9 --. could not readily take the lure. TotaL______------52 56 117 7--- 2 239

TABLE I.-Monthly Juminary of all Jpecime1lJ of Euthynnus yaito FEMALES taken by the Spencer F. Baird, October 194i-NorJembrr 1948 II~';'ea-1Ri~:n-\ SPi~~n-1 k~:n October _ Month Ripe \ SpentI ITotal E~E~~~~::::::::::: ~~~~~~ :::::ij: ::::i: ~~~~~~~ February______:::::: 1 1 3 37 1 .22! March______4 3 1 1 9 ALL FISH ""priL______5 3 1 17 26 May______7 10 3 2 16._ 38 October _ f~i;::::::::::::::::: ~_ ---T ~ ::::::::: 1~ ~;:;~:::::::::::::: :::::: ---T ~ -----g------2- . ~ January______1 10 27 ----i- ----1-;- 39 ~~'i;~-;,~:::::::::::: February______26 23 9 37 .. 109 :::::: ::::i: ::::i: :::::::: ::::j: ::::::: :::::i March______5 6·1 2 14 November______28 4 5 37 ""prjL______5 6 10 17 1 39 ------I\day ~______10 14 11 34 16 4 89 Total______14 .5 32 22 88 4 205 June .______2 1 14 2 4 23

TABLE 2.-Lenglh-frequenry and degree of maturity of troll-caught Euthynnus yaitofrom Philippine waterJ, taken by the Spencer F. Baird, October 1947-Nove'Tllbtr 1948 .

Immature Ripening Ripe Spawning Spent Unknown J Length in millimeten All Male Fe- Fe­ Fe­ Male Fe­ Male Fe­ All Male Fe­ male All Male male All Male male All male All male male '------1------280-289 • 1 _ 290-299_" _ 300-309 _

I~ftmm~~mmmm _:::1: ~::I :_:I ~mJ~ mm ~mJ~ ~;;-i; ;:;~~; mm mm mm ~m~: ~m:~ mm mm :::T mm m~~: 370-379_"______1 1 2 1 1 1 1 _ 380-389______3 3 2 1 1 • 390-399______1 1 1 1 4()()-409______1 1 2 2 410-419______1 1 4 • ---T ------T ~~~~~~ ~~~~~~ :::::: ~~}~ :::::: ~~~~~~ ::::i: :::::: :::::: .20-429______1 1 5 2 3 • ----j- 1 1 1 _ 2 _ .3(),-439 " "__ -1 1 _ 4 2 2 1 1 ------or ------or _ 44O,-449_~ · . 1 1 1 1 • 3 2 3 3 4 4 2 _ 450-459 .______1 --____ ·1 I ----6-- 1 6 1 5 5 4 ---T 4 • 1 _ f60-469_ 1 1 12 6 470-479 •· "__ 11- 8 3· ~ ---T 1 1~ l~ ---T ~ ~ ---T :::::: ----OJ 480-489______11 • 7 3 2 ----i- 9 8 1 8 8 ~ __ • " _ 490-499 .~ 10 7 3 6 • 2 8 7 l liZ Z •_ See footnote at eDd of table. 412 FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE

TABLE 2.-Ltngth-frequency and degree of maturity of troll-caught Euthynnus yaito from Philippine waters, taken by the Spencer F. Baird, ",' , October 1947-Noflfmber 1948-Continued

Immature Rip.ninB, Rip. Spawning Sp.nt Unknown·· . Length in millimeters F~ Mal. F.­ F.­ Mal. F.­ Male F.­ Mal. F.· All male All Mal. mal. All Mal. mal. All mal. All mal. All male ""'"-"-'---'-----1------500-509 •• :__ 5 3 2 10 7 6 5 11 11 ._ 5'lO-519 ~______4 3 1 5 4 6 6 __ 7 --- 2 5 1 - 1 520-529______3 1 2 3 3 8 5 ----3 9 1 8 • •_ 530-539 .__ 3 1 2 4 4 ._ 4 3 1 9 9 1 1 _ 540-549______5 4 1 2 1 ----1 13 11 2 6 6 •_ 550-559 .___ 4 3 1 7 4 3 5 5 10 2 8 • _ 560-569 •• 2 2 4 2 2 5 4 -- 1 5 2 3 1 1 _ 570-579______2 1 1 5 3 2 5 4 1 2 2 1 •__ ._ ~~8::~~L:::::::::::::::::: ~ ~ ~ ~ ~ ~_ 600-609 • :::::: ::::::•__ •• :::::: ---T• ---T ::::::.__ t32 1 2 6 3---T 3 2 2 __ • :::::: ::::::• 610-619 ••• __ • .____ 5 5 ._ _ • 620-629 •.•• • .____ 1 1 5 3 - 2 1 ::____ 1 :_ 630-639 ._____ 1 1 2 2 3 2 1 1 1 1 •• 640-649______1 1 ._ 6 5 1 • 650-659 • ._ 1 1 1 1 • 660-669______1 1 1 1 • • 670-679 •• • 1 1 2 2 •_ 680-689 ••_ 1 1 • •• •• • _ ------TotaL_._~______19 5 14 97' 52 45 88 56 J2 137 115 22 95 7 88 24 4 2

. .I-Includes those specimens in which the sex and gonad condition were not known or one or other was unknown.

TABLE 3.-Locality, length, st.~, degree of maturity, and gonad TABLE 3.-Local1"ty. lmgth, sex, degree of maturity, and gonad weight of Euthynnus yaito takm by the Spencer F. Baird in weight of Euthynnus yaito take-n by the Spencer F. Baird in . Philippine «'aters, October 1947-No~ember 1948 Philippine waters, October 1947-Nooember 1948-Continued

Fork Fork I.~gth le~gth .. Degre. of Gonad Degre. of Gonad , Dat. ~cality ID weight Dat• Locality ID S•• S." maturity maturity weight milli- in grams milli- in gram. meters meters

1917 ' 1948 Nov. 11 , ia;:;,boanga _ F.mal._____ Ripe___ • ____ F.male • Spawning••__ 580 _____do______135.0 Jan. '14 Pilas Island. Siilu Ar- 600 140.0 Dec. 5 Sulu Archipelago _ 585 ___do____ • __ 141.0 chipclago. ___do_. _____ Rip.ning______• _do ______Mal. • ._.__ do. _ Dec. 14 Pilas Island" Sulu 621 123.5 14 526 ___ do do. _ 104.0 .. "_Archip.lago., "" 14 _•• __ do ___ •______._ 611 113.5 ,.14 .do •_ ~do_. 557. ______do__ • ___ 111.3 14 _. _. _do ______._ 605 F.mal. • do _ , 177.5 14. do • Mal.______Spawning______• __ do __ ••______do do _ , 14 do _ 625 __ .do______103.5 14 ____ .do_____ • ______481 63.0 582 Ripe______37.0 14 550 Mal.______Rip. _ 101.0 ...... 14 .. ,_·_do_~_~~ ,__ "_,_ ___do__ " ____ Rip.ning______do______._ F.mal._____ Spawning. _ 14 do •_ 533' ___ do______do______7J .1 14 477 67.7 529 52.8 14 ____ .do______634 Mal.______Rip. • 14 do •_ ___ do ______do______do ___ • ______do Spawning _ 133.7 557 91.2 14 _____ do______545 F.mal. do _ , 98.7, ,- .. "14 _::._i:lo::':. : :'- 5% ___ do____ : __ Spawllins____ 84.4 14 571 Dec. 15 Zamboallga • ___do______do______do __ • ______do • __do _ 136.0 . 15 _: do _ 584 ___ do______do______130.0 14 _____ do__ • ______540 ___do" do_. • 74.6 15 do _ 607 ___do __ • ______do______140.0 14 _____ do ___ ••______620 Mal. do _ 133.5 570 120.0 14 591 92.7 15 do _ ___do. ______do___ • __ _. ___ do______F.male do _ 53S 98.0 14 _____ do______601 126.0 15, do _ Femalc_____ Mal. do • __ 15 do •• __ 566 99.5 14 497 5303 Mal••••____ - Sp~-;.;~i-ng-::: ___ • _do ______• __ F.mal._____ Ripe • 1'5 do _ 545 ___ do______de______162.5 14 ____ • do______430 __ .do ••__ do _ 41.0 491 73.0 14 562 59.5 15 do _ Female______do____ • ______do do • 15 do •_ 499 69.0 14 _____ do____ • ______457 58.5 471 Male.__ •__ • -Spa-;.;~i~g--::: 49.0 14 454 Mal.______Spawning _ 79.1 15 do •_ F.male_____ Ripening ______do ______do. • ._.do _ 15 do _ 488 47.0 14 _____do______• __ 484 ___do • __ do • 61.6 470 Mal.______Spawning____ 43.0 14 496 55.0 15 do _ ___do ______do______do ______F.male_____ Rip. _ 15 do _ 479 ___ do______do______7-1.0 14 _____ do ______• ___ 485 72.0 474 Mal. • do _ 15 do •_ ___ do______. ___ do______46.5 14 • ____ do______•_ 523 ___ do do__ • __ • 64.0 15 do _ 455 ___ do______39.0 14 _____ do ___ • ______542 75.0 466 • ____ do______63.0 522 F.mal. Spawning _ 75.0 Dec. 16 do _ ___ do ______• ___ .do______14 _____ do______do_ •• do _ 16 do _ 592 86.0 14 _____ do ______540 113.5 462 F.mal._____ Ripening____ 39.0 14 560 ___ do_ •••• do _ 98.0 F.b. 19 Port Santa Maria, 550 Male•••_.__ Rip._. _ 37.5 1918 Zamboanga P.nin- Jan. 7 South Sulu Se. _ 594 Mal._._____ Spawning____ 1JS.6 sula. 7 .do _ F.mal._____ • ____ do. ______do______7 do _ 603 82.4 19 _____do______480 F.mal._____ Sp.nt______19.4 556 Mal.______do______53.2 19 622 Mal. Rip.______188.6 7 • do _ ___do______do_. ______do_. ___ • ______F.male • .____ 37.7 7 do _ 618 ___do______.do______129.0 19 530 (1) ._. _ 578 72.4 19 ___ • _do ______645 77 • do •_ Femal.______do______do______(1)_. --- • _ • do ••_ 593 Mal.______do______162.5 19 _____do______• _____ 576 7 • __ ._do •_ 613 ___do______do______81.0 19 _____ do______476 __ •••do ._. _ 545 ___do_____ ._ • ____ do______70.0 19 _____do______424 7 620 102.5 19 422 ~ do ______do______637 ___do__ • __ ._ Rip.ning____ 97.5 19 582 7 do•• _ ___do_._. ___ Spawning______do ______!~!~~ ~~~~ ~~~~~~~~~~~~~ ~~~~~~~~ _____ do _ 656 178.5 19 • ____ do•• ______446 566 F.mal._____ Sp.nt______62.3 19 443 (1) •• ••_ 7 do •_ ___do______Ripe______do_____ • ______Mal. Ripe______150.0 Jan. 12 __ •__ do •• 601 • ____do______154.5 19 _____do______• ___ 687 m ___do____ ••• 70.0 19 56S ._.do Spawning____ 43.0 I Pr.s.rved in the rouneL SPAWNING OF PHILIPPINE TUNA 413

TABLE 3.-Loca/ity, ·lmgth, SIX, degrte of maturity, alld gonad TABLE 3.-Loca/ity, 1l1lgtk, me. degree ·of n~aturity, and gonad weight of Euthynnus yaito takm by t/ie Spencer F. Baird in weight of Euthynnus yaito taken by the Spencer F. Baird ill Philippilll waters, October 1947-NOfJemher 1948-Continued Philippine waurs, October 1947-NorJelllher 1948-Continued

Fork Fork le!'gth Degree of Gonad length Degree of Gonad pate Locality in 'Sex Date Locality in maturity .weiglit Sex maturity weight .. milli- m graDtI milli­ in grams meters meters

19#8 1m Feb. 19 Port Santa Maria. 558 Female_____ Spent______37. 6 Feb. 19 Port Santa Maria, 494 Female Spawning____ 44.6 Zamboanga Penin- Z.,mboanga Penin­ lula. sula. _____ do______do______do______do • __ 458 do Spent______13.6 19 _____do______560 37. 5 19 19 510 Male______Spawning____ _ do _ 478 Male Ripening____ 19.2 _____do______do______34. 5 19 19 503 Ripening____ 165. o 19 _ do _ 519 Female Spent______32.2 ___ -"_do ______. _____ Female_____ Spent______do _ ~88 do do______23.1 19 _____ do______535 63. 1 19 19 540 Male______Ripening ______do _ 508 • __ do do______23.5 __ • __ do._.______27. 5 19 19 510 Female_____ Spent______33. 8 Feb. 21 Zamboallga ~ _ 638 Male Spawning____ 22.1.5 _____ do______Male______Ripening____ 339 C'l--- Immature _ 19 _____ do______562 ___ do______33. o Feb. 23 Margosatubig. Mora 19 642 Ripe______do._.______do______do______llO. 3 _____Gulfdo _ 355 C'l--- do •• 19 _____do____ • ______556 ___ do______58. 1 23 19 592 Ripening______do _ 345 C'l do ______do______do______44. 2 23 _____ do _ 19 651 Ripe______90. 5 23 355 C'I------do _ 19 _____do______575 Female_____ SpenL______283 do______1 _____ do ______do______do______54. 4 Mar. 2 Bangka Passage, ('l------19 ___ __do______600 69. 1 Celebes 19 558 Male______Spawning______do _ 283 Ripe • 28.1 _____ do______do______67. o 2 _____ do • __ (/J------._ 19 564- Ripening____ 26. 2 571 Female • do______161.2 _____ do______do______do______o _ do _ 521 do Spawning • 80.9 19 673 ___ do______221. 6 2 19 _____ do______555 Spawning____ _ do _ 542 do Spent______56.3 _____do______Spent______8. 3 2 _ do _ 19 _____do______520 Female_____ 48. 3 2 520 Male Spawning____ 56.9 19 510 ___ do______do______do _ 498 Female_____ 48.9 ____ _do______Male______44. 9 2 _ do _ 19 560 Ripe______69. 7 2 500 do • __ Spawning____ 69.3 _____ do______Female_____ Spent______575 Male • do______159.2 19 _. ___ do______508 29. 8 Mar. 13 West coast of Panay_ 19 570 Male______Ripening____ _ do _ 553 Female Ripe.______185.7 _____do______do______do______28. 2 13 _ do _ 508 do .do______220.0 19 _____do______560 ___ do______21. 9 13 _ do _ 19 462 _____ do______505 do .do______119.0 _____do______do______do______IS. 6 13 _ do _ 19 _____do______540 33. 7 13 406 Male Spawning • 38.7 19 587 Female_____ SpenL______do _ 455 Female • __ do__ " __ • 43.8 _____ do______Male______42. 6 13 19 494 Ripening_ ._. 28. ~ North Sulu Sea _ 447 Male • do______39.8 _____ do______Female_____ Spent______2 Apr. _ do _ 19 _____do______509 _____ do______48. 8 440 Female Spent______24.0 19 490 ___ do______6 _ do _ 473 Male • Spawning____ 61.7 ____ _do______Malc______Ripe______18. 6 _. do _ 19 _____ do______• ____ 472 25. 2 6 406 Female SpenL______16.0 19 516 Female_____ Sl?ent" ___ • __ _ do _ 443 do do______21.7 _____ do______do ______25. 3 6 _ do • 19 466 RlpenInS____ 14. 7 6 443 do do______51.5 _, ___ do______do______Spent______do _ Ripe.~. 19 _.___ do______562 35. 2 6 448 Male • 36.8 19 5% ___ do______do______do _ 426 Female Immature___ 6.8 _____ do______Male______Ripe______51. 5 6 600 Male Ripe • 56.9 19 _. ___ do______668 125. 5 Apr. ~ Sulu Archipelago _ 19 558 Female____ . Spent______do _ 543 Female Spent ,"__ 50.4 _____do______do______41. 4 _ do _ 485 do 24.9 19 _____do______530 • __ ._do______48. 3 8 do______19 530 __.do______do_____ • _ do _ 450 do Immature___ 8.9 _____do__ •______Male______Ripe______34. 7 8 _ do _ 412 do do______3.4 19 _____do______• ______532 26. 1 8 ___ do______• Ripening______do " _ J~5 do do______1.4 19 _____ do______595 ___ do______• 22. 1 8 _____ do _ 19 520 Ripe______8 63' 2 do Spawning____ 66.4 _____do______• ___ do_. ______do______32. 3 _ do _ ___ do SpenL______42.4 19 _____do______550 ___ do______43- 5 8 _ do _ 5J 0 19 515 _____ do______472 do "do______24.4 _____ do______"____ ,_ ___ do______do______27. 8 8 _ do _ 19 _____ do______509 34. 3 8 490 Male ._ Ripe______66.3 19 603 Female_____ SpenL______do _ 540 Female Spent • 66.2 _____ do______do______do______51. 7 8 _ do _ 509 do de______30.4 19 _____ do_.______SIS 28.5 8 19 SOl Male______Ripening____ _ do _ 663 Male Spawning____ 99.9 _____ do______18.5 8 • do _ 19 471 Female_____ Spawning____ 14.5 8 500 Female Spent______31. 1 _____ do______Male______Ripe______do _ 19 _____ do______573 ___ do______95.9 8 553 Male Spawning____ 70.3 19 554 Ripening____ _ do _ 542 Female Spent______46.5 _____ do ______do______do______51.7 8 _ do _ 19 _____ do______559 51.6 8 525 Male Spawning____ 38.1 19 460 ___ do______do______do _ 419 (1) Immature___ 4.6 _____ do ______Female_____ Spent______7.6 8 _ do _ 19 _____ do______484 ___ do______24.8 8 561 Female Spent______38.2 19 500 _____do______do _ 592 do Ripe______116.1 _____ do______Male______29.3 8 _ do _ 19 _,___ do______463 Ripening____ 10.4 8 648 Male ._ Spawning____ 123.6 19 470 Female_____ SpenL______do _ 545 Female SpenL •______do______do______do______17.9 8 585 do do • 66.0 19 466 8 _ do ______do______Male______11.4 _ do _ 375 do Immature__ • 1.3 19 _____ do______475 ___ do______Ripeningdo______8.3 8 19 548 _ do _ 484 do Spent______33.8 _____do ______Female_____ 36.8 Apr. 17 _ do _ 19 533 SpenL______23.4 17 484 Male Spawning • 10.5 19 _____ do______518 Male______Ripening____ _ do _ 504 Female • Ripe______44.9 _____ do______SpenL ______13.4 17 _____ do _ 19 _____ do______526 Fem:tle_____ 26.8 17 593 do SpenL______94.0 19 510 Male______Ripening____ _ do _ 567 Male Spawning • 46.1 _____ do ______do______Ripe______18.5 Apr. 18 _____ do _ 485 do do • 29.0 19 _____ do______498 21.2 18 19 Female_____ Spa\vning____ 543 Female_. Ripe______83.6 _____ do______534 Male______44.9 Apr. 21 Welt Zamboanga 19 _____do______472 ___ do______Ripeningdo______7.6 Peninsula. 19 514 5 North Sulu Sea • Sll Male Spawning • 12.0 _____ do______Female_____ 13. 1 May 5 do _ 19 _____ do______523 ___ do______SpenLdo______28.4 532 Female Ripening____ 18.2 19 467 5 do _ 495 Male Spawning____ 10.8 _____ do______Male______16.7 5 do _ 19 _____do______477 12.5 452 Female. Ripening_____ 10.2 ___ do______-Rip~:::::::: 5 do _ 475 Male do______6.5 19 _____do______493 ___ do______29.3 19 502 _____ do_.____ 5 do _ 499 do do______6.5 _____ do____ • ______22.7 5 do _ 19 _____ do______522 Female_____ Spent______38.5 498 Female do______ZO.1 19 507 Male______Ripe______5 do _ 494 do do______17.0 _____ do____ • ______do______._do______17.9 19 __ • __do____ • ______483 ___ do______9.9 May 7 Pila. Island, Sulu Ar· 574 Male • Ripe______23.8 19 477 _____ do_.______do____ • ______Spent______11. 1 chipelago. 19 SOl Female_____ 21.7 7 do _ SIS Female ._ Spawning____ 41.5 _____ do___ ._.______Male______Ripe______7 do _ 556 do Ripe______92.0 19 _____ do______503 15.9 19 480 Female_____ Spent______7 do _ 359 (1) Immature •______do___ • ______Male______Ripe______17.3 7 do _ 19 485 ___ do______22.1 548 Male______Spawning____ 85.1 19 _____ do______460 Ripening____ 7 do _ 527 do do______25.0 _____ do______do______6.5 7 do _ 19 _____ do______510 Spawning___ • 74.1 505 Female Spent______14.7 19 527 Female_____ Speut.______28.3 7 do ...", 514 . Male Spawning__•• 22.1 I Gonads insufficiently developed to determine the sex. 414 FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE

TABLE 3.-Lotality, lmgth. sex, degru oj"maturity, and gonad TABLE 3.-Locality, length, sex, degru of maturity, and gonad .",'eight of Euthynnus yaito taken by the Spencer F. Baird in rveight of Euthynnus yaito taken by the Spencer F. Baird in Philippine waters, October 1947-No~e1llber 1.948-Continued . Philippine waters, October 19.f.i-No~ember 1948-Continued . -- ...... Fork Fork 1.,:,Bth Degro. of Gonad le,:,gth Gonad Dat. Lo.i:slilY In weight Dato Dogro. of SOlI: maturity Locality m S.z maturity weight milli- in grams milli- in graIDI meters meters

1948 Mal._••____ 1948 May 7 Pilas Island,Sulu Ar- 547 Spawning.____ 39.1 June 29 Busuanga Islands, 448 Mal•.______Rip•.•_____ 21.o chipelago. - _____ do______do______do______China Sea. _____ do______7 608 100.6 29 _____ d" _• ______431 Female______do______do______Ripe______• _____ do ______Male___ •______do __ • ___ 14.o 7 _____ do_____ • ______570 71.8 29 436 9.7 7 591 ___do______Spawning____ _. ___ do ______do. ______do______do______do______do______41.4 29 _._ ••do______425 _____ d,,______6.2 7 _____ do______540 44.5 29 491 Female_____ 70.o 7 Femalc_____ SpenL __ • ______Llo ______Male______do______do______• _____ 500 ___ do______27.5 29 _____ do ______428 21.o 7 511 Ripening____ 20.8 Femal.______do______do ______do______29 _••_.do______492 ___ do______do______42.4 7 _____ do __ •_• ______400 Immi1ture ___ 3.1 29 _____ do ______401 24.5 7 521 ___ do.______Ripening ____ Male______Ripenins______do __ • ______Ripe______22.5 29 _____ do______362 2.o 7 539 Mole______29.3 29 Female__ •__ Ripe______do ______• ______do______do______454 Male______.do______18.o 7 _____ do ______• ___ 548 Spawning.___ 53.5 29 450 18.3 May 8 547 Female_____ Ripening____ 42.0 July 11 South Sulu S.a______388 _._do______Immature __ .. 2. __ •__ do ______Male______do ______~_ ___ do______o 8 454 Spawning____ 3.4 II 486 Spawning____ 27.3 8 _____ do ______501 Female_____ Ripening____ Sea __ ___ do______do______44.8 July 12 Southwest Sulu 385 ___ do______Immature___ 2.o 8 549 Mal.____ ••_ Spawning____ 54.5 12 ____ .do______Spawning______do______Female______•• _do______484 37.o 8 _____ do" ______644 96.5 July 14 Balabac Island, Sulu 582 Femal.____ • Spent____ ••_ 89. 7 8 539 Mal.______• __ do______do ______• ______do______do______25.9 __ __S.a._do______• __ ___ do___ • ______do___ • __ 8 ____ .do_ • ___ • ______500 32.5 14 555 104. 7 8 527 Female_••__ Sp.nt______35.7 _____ do____ • ______• Male______.do____ •______do______do______14 _____ do______548 ___ do______Spawning._._do______75.5 8 530 ___do______do______41.0 14 549 82. 5 8 _____do __ • ______525 _____ do____ • ______Femal._____ Spent.______.do______do______.do______39.0 14· _____ do______550 ___ do______92. 5 8 536 36.9 14 450 Rip••______45. o _____do______do______.do______do______do______• Ripening____ 8 __ ___do______532 ___ do__ • ______.do______3-1.5 14 406 ___ do______8. o 8 531 26.2 _____ do______Ripe______do______._ Male___ •___ 14 _____ do ______565 Male______87. o 8 _____ do ___ • ______521 Spawning____ 21.9 14 611 Spawning____ 178. o 8 620 F.mal••••__ Spent______do ______do______do_.______do______Male______86.5 14 _____ do ______546 48. 5 8 _____ do______498 Ripening____ 11.5 14 571 Femal._____ ~.nt------25. 9 ___ do__ •• __ • Spawning~ _. ___ do ______8 _____ do ______492 ___ 22.0 14 508 Male______• 41. 3 Female______do ______Femal.______,pe------do___ ._. 8 _____ do ______498 Ripenins ____ 18.2 14 _____ do______458 63. 5 8 (1) Immature. __ ___ do______do______do ______361 • ____ do______------14 457 _____do______50. o 8 _____ do ______345 (I) Aug. 9 Si~,~f~y More 348 Male______18. o 8 459 Male______Spawning____ ----in Bay, _____ do______do______• __ •••do______do______8 "____ do ______566 ___ do______42.6 Oct. 31 North Palawan, 467 Spawning____ 9. o 8 554 _____ do______. ___ do ______21.9 ___ China• _do ______Sea. _____do______8 __ __ _do______578 F.male_____ Ripening____ 15.5 31 432 ___ do______11. Male______do______F.mal._____ o 8 513 ___ do______• Immaturc___ 3.3 31 524 SpenL______25. o May 10 Moro Gulf, Mindanao 515 Ripe______• _____ do______Male______Spawning______do____ •______do______do______58.1 31 _____ do______425 9. o 10 531 59.8 31 412 Femal._____ Ripening____ 9. May 12 _____ do____ • ______do______Ripening______do ______Sp.nt______o _____ do _____ • ______476 ___ do____ • __ 7.3 31 _____ do ______507 Mal.______• 15. o 12 383 Immaturc ___ 2.0 Femal.______do______do ______Female______.do______31 _____ do ______448 Male______12. o 12 _____ do ______343 4.2 31 473 Spawning____ 8. o 12 344 Male_.__ • ______do______do______Femal._.___ Sp.nL_____ • F.male______.do______2.5 31 _____ do ______455 _____ do______25. o May 15 Davae Gulf, Min- 348 3.8 31 550 Male______10. o danao. _____ do______do______Spawning______do ___ • ______do______do______31 _____ do ______503 • __ do______10. o 15 _____ do ______343 ___ do______.do______2.2 31 550 SpenL______14. o 15 356 _____ do______Female_____ Ripe______do______Male______• _____ do______7.2 31 _____ do______463 SO. o 15 358 2.1 31 511 Male______Spent______5. 15 ___ • _do ______Femole______do______do ______do______o _____ do______331 ___ do______4.8 Nov. 2 _____ do ______496 ___ do ______Rip.ning____ 5. o 15 334 _____ do______SpenL______do ______do ______Spent______3.4 Nov. 4 _____ do ______550 ___ do______do______6. o 15 435 J 13.1 ___do______Ripe______.' 4 ____ •do ______565 _____ do______10. o May 17 _____Sulu doArchipelago.______564, 51.5 4 465 Femal._____ 20. o 17 64,8 Mal.______Spawning______do______do______do______• ____ do______do______do______84.5 4 _____ do______464 ___ do______do______26. o 17 _____ do______677 65.8 4 450 10. o 17 626 F.male_____ Spent______Male______, Ripe______do______._ Male______Ripe______58.9 Nov. 5 Northeast Palawan_. 428 8. o 17 636 35.0 North Palawan______do______Ripening______do______F.mal._____ Spent______Nov. 6 _____ do _____ • ______485 _____ do______3. o 17 _____ do______637 51.5 6 481 Female_____ 6. o 17 605 Mal.______Spawning______do______Male______do______do______do______do______71.0 6 _____ do ______• 490 ___ do______3. o 17 _____do ______64,1 69.5 6 482 _____ do______6. 17 ___ do______• ____ do______do_____ • ______Femal.______do______o _____ do __ • ______566 ___ do______106.0 6 487 18. o 17 642 _____do______do______do______do______do______.do______97.5 Nov. 7 Northeast Palawan__ 478 ___ do______do______13. o 17 612 65.5 • ____ do ______do____ • ______do______do______7 _____ do ______482 Male______do______14. o 17 _____ do ______._ 549 ___ do______54.0 7 473 7. o 17 587 ____ .do______do______Femal.______do______do______do______• __do______52.0 7 _____ do______481 _____ do______16. o 17 583 732.0 Male______• _do __ • ______._ ___ do______do______7 _____ do ______470 ___ do______do______7. o 17 _____ do ______516 45.0 7 495 7. 17 ___ do______Ripe______do ______do ______do______o _____ do______532 ___ do ___ ._._ 19.9 7 _____ do ______475 4. o 17 499 Spawning____ 31.0 Femal.______do______do_____ • ______do______do______7 _____ do ______402 _____ do___ • __ 8.o 17 ____ .do______634 35.5 7 380 Mole______4. 17 604 Female_.___ Ripe______• ___ .do______do______do______o _. ___ do ______• ______do______143.4 7 420 4.o 17 _____ do______554 Spent______27.8 Nov. 8 West Sulu S.a______420 Female______do_. ___ • 9. May 18 ___ do______do______do______do______do______o ___ ._do______556 Male______51.0 8 420 9.o 18 568 Ripe______46.2 • ____ do ______Male______do______. ___ do. ______~ __ 8 430 2.o 18 542 F.male___ ._ Spent______do ______Female__ •______do______do______do______do______37.5 8 _____ do______•• 414 8.o 18 Sea______557 ___ do______do______35.5 8 410 m______._ Immature___ Jun. 16 _____NorthdoSulu______485 12.7 Nov. 9 Southwest Sulu Sea__ 416 Female_____ Ripening__ .... -----ii.-0 16 ___do______do______do ______do______do______do______463 ___do______15.0 9 _____do ______428 10.o 16 461 Immaturc___ 3.2 Male____ ••_ Spawning.__ • _____ do______do______do______9 _____do ______477 ___ do___ • ______do___ ••_ 16.o 16 _____ do______442 1".2 9 521 12. 16 Male____ • __ Spawning__ .______do ______o _____ do ______515 10.6 9 _____do______522 Femal.___ •• Ripening____ 24. o 16 467 Female_____ Spent______15.6 __ .do______Rip.______do ______• Male____ • __ 9 _____ do __ ._.______• 508 Male______22. o 16 _____do __ ••______479 Spawning____ 15.8 9 441 Spawning____ 10.o 16 458 F.mal._____ SpenL______do ______• ___ •• ___ do______Ripe______• ____ do ______Male____ •__ Ripe______13.6 Nov. 10 _____ do____ • _____ ••• 520 10.o Jun. 27 _____ do ______512 37.5 10 468 Female_____ Ripening____ 16.o 27 580 ___ do_. ______do______do ____ • ______do______do__ • ______do______do______• ____ do______85.5 Nov. 11 _____ do__ •___ • ______442 ___do______8.o 27 508 35.8 11 475 _____do____ .______do ______do______do____ ~ ______do.______._ 6.o 27 498 35.2 11 535 ___ do._._._. ---.-Ilo••••-- 20.o SPAWNING OF PHILIPPINE TUNA 415

TABLE 3.-Locality, ltngth, StX, dtgru of maturity, and gonad K. pelamis were males, but the larger percentage of wtight of Euthynnus yaito takm by the Spencer F. Baird in Philippine waters, Octobn 1947-NorJtlllbn 1948-Continued spent fish were females. From the information available the reversal of sex dominance in spawning Fork and spent fish cannot be explained. The lack of length Degree of Gonad Date Locality in Se", maturity weight milli­ in gran18 spent males may be partly explained as resulting meters from misidentification of the stage of maturity.'

1918 At the present time there is no way to determine Nov. 11 Southwelt Sulu Sea __ 50S Female • Ripening _ 18.0 • do_. __ •_ Male______Ripe _ accurately the differences between males approach­ 11 _____do •_ SIS 6.0 ___ do Ripening _ 4.0 11 _____do. _ 480 ___do do ._ ing spawning and those past the peak of spawning. 11 _____do _ 465 _._do do _ 4.0 11 _____do •_ 506 Female do _ 8.0 The larger percentage of spawning males caught 11 462 14.0 _____ do _ Male • Spawning _ 11 _. do __ •• _ 480 ___ do • do _ 12.0 probably can be explained in that the aggressiveness 11 503 8.0 __ • __do__ •• _ Femalc_____ Ripening__ .. _ 11 __do. __ ._. _ 472 ___ do do •_ 14.0 of the male during spawning makes him more prone 11 ____ .do__ ••• _ 485 12.0 Nov. 12 490 Male do _ 4.0 ~_ ___ do Ripe _ to strike at a lure. , 12 _ ••do•• _ 430 6.0 ____ .do • ._ ___ do______Spawning _ 12 _____do • __ 575 ___ do do _ 48.0 The only reference available on the spawning of 12 _____do _ 585 ___ do do _ 50.0 12 _____do _ 585 48.0 this species in the western Pacific (Kishinouye 1923) 12 545 Female Spent _ 44.0 West Sulu Sea _ ___ do______Ripening _ Nov. 13 _____ do _ 385 __ .do ._d" _ 10.0 indicates that in Japan K. pclamis spawns from May 13 391 10.0 _____ do _ Male______Spawning _ 13 _____ do _ 500 __ .do do _ 22.0 to August. This period coincides with what is be­ 13 _____do _ 505 17.0 ___ do d" _ 23.0 13 _____do _ 490 ___ do Spent. _ lieved to be the peak of spawning in Philippine 13 _____do _ 525 9.0 13 482 Female. do _ 19.0 __ • __ do _ Male Spawning • waters. Schaefer and Marr (1948) are of the opin­ 13 485 ___ d', do _ 12.0 13 _. do •_ 487 12.0 ion that along the west coast of Central America _____do •• _ ___ .10 do _ 17.0 13 _____ do _ 470 __ .do do _ 13 _____do _ 475 ___ do d,, _ 18. 0 pclamis spawns at least from January into March. 13 472 12.0 South Sulu Sea. _ 420 ___ do______Ripening _ 5.0 Nov. 16 • do _ ___ do do _ Although there is evidence that it also spawns dur­ 16 _____ do •_ 460 Female do _ 12.0 16 • do _ 410 ___ do .10 _ 8.0 ing this time in Philippine waters, spawning of the 16 ____ .do _ 460 Male • __ do _ 14.0 16 480 11.0 _____ do _ Female Ripe_. _ greatest intensity occurs during the early summer Nov. 17 • .do _ 445 40.0 17 ____ .do_. ._ 440 30.0 months. 17 410 ~::::=';I~~~~::[::: :~~:::~:: 30.0 17 ____ .do _ 670 Male 1 Spawning _ 145.0 _____ do••• •_ ~ d(~ ~ The data show that in Philippine waters Katsu­ 17 649 ___ do __ _ 78.0 _____do • __ ._ __ ~do do~ _ 17 _____ do ._ 625 90.0 WOUlIS pcla-m-is spawns through the year. The prin­ 17 428 Female_._._ Ripe _ 40.0 17 _____ do _ 467 ___ do Ripening ~ 10.0 North Sulu Sea _ M:J.lc Spawning _ cipal spawning period, however, begins in February Nov. 22 ____ •do ._ 405 20.0 22 375 Ftmale: Ripening _ 4.0 _____ do _ Spawning~ and reaches its peak in June. Spawning activity 22 _____ do _ 442 Mo.lc _ 20.0 22 400 ___ do. .do _ 10.0 then decreases until a period of minimum activity is West of Mindoro • _ FCI1I:l)C 1 RipcninK _ Nov. 23 _____ do ._ 365 ___ do .do _ 6.0 23 _____do • ••_ 360 8.0 reached during September and October followed by a 23 370 Male______Sp'w"illg _ 8.0 slight increase in November and December and another decline during January. A few ripe fish Although the sample of ripening fish is too small taken during September and December suggests that to permit definite conclusions, there are indications some spawning may also occur in October and Jan­ of the possible trend in the maturation of this species. uary, although no spawning or spent fish were caught Those fish caught during the first half of the year during those months. appear to have ripening gonads more fuIIy developed than those taken during the latter half. This sug­ NEOTHUNNUS MACROPTERUS gests that spawning occurs mainly during' the late (TEMMINCK AND SCHLEGEL) spring and summer months. Ripe K. pelamis were taken throughout the islands during the entire year, In tables 7, 8, and 9 and figure 3 are presented the but in the greatest abundance in April, May, June, field data for Ncotlummu macroptcNtS (yellowfin and July, The larger number of ripe fish taken dur­ tuna). , ing this period is probably indicative of a period of Almost one-half (48.5 percent) of the yellowfin, more intensive spawning. tuna caught were immature and too poorly devel­ Spawning and spent fish were taken from March oped to yield information on spawning. The sex through July and scattered specimens during the of 61 percent of the immature fish could not be remainder of the year. The majority of spawning determined by the usual field methods.

S70654°-60--2 41'6' FJSHEllY BULLETIN OF 'rJ-.IE FISH AND WILDLIFE SERVICE Do;;"'"..,."""'"'T"'""""--:-"""7"--:----.:....------. ... ,

:.. . ~

32 LENGTH FREQUENCY ~!!.!!!...pelomis

,28

" 24~;c

~ 20 .. .a.. ' 'S ,~ '16' Z .....

.,

.' .

',:

3~0 400 .q50 5QO 5~O 600 6~0 100 Length in mil!imetllrs

FIGlTR'E 2:~Len~th-frequencydistribution of K"/m:w;; us pd'i'llli.f takt'n in Philippine waters from October 1947 through November 1948. .------, I.

I. LENGTH FREQUENCY Neothunnus macfopflrus

14

IZ' ~ ;;: '0 10 .. ...~ E z"

400 4.0 .00 550 R"O b50 800 "0 Lenoth II) millimetels

FIGURE 3.-Lcngth-frequency distribution of NeothuJlJlus 1JwcropI<')"uS taken in Philippine waters from October 1947 through November J.~).1g. · SPAWNINR· OF PHILIPPINE TUNA 417

TABLE 4.-Monthly. Slt111111ary· of all spm'mens of troll-callgkt TABLE 4,-Monthly summary of all ·specimt1ls of troll-caught Katsuwonus pelamis, taken by tlte Spencer F. Baird, October Katsuwonus .pelamis, taken by the Spencer F. Baird, October 1947-Nooember 1948 .. . . 1947-No!Jember 1948-Continued ~IR!pen- Month ture Ing R'pI e Isp.awn-!109 Spent

ALL FISH MAV;:S-Continued

i%~~~j,~~======October ~~~:~~ - _ ~mmm:m mm!:::T :::;: ::::::;:I~~~~~~ ~~:~:;: ::::~ ======It ====:=== j ==:=:== I! ApriL .____ 5 I 31 7 I 2 47 Novem;::~;~~~~~~~~~~ ~~~ ~I~ ~~ Mar -___ I 6 33 8 II. I 60 June .____ 6 42 8 3J . 89 Jul}, .____ 25 13 I 19 FEMALES Augllsl.______4 II 2 I 18 -~--~-~--~-- September______3 I 4 October • _ October ------November_~ __ • __ ~ __ • • • •_ November______2 13 4 I 2· 22 December______.3 9 5 17 ------JaMary______I I TotaL ~____ 6 30 173 60 50 16 335 February______3 I 2 6 March .__ 7 5 ------2-- 12 MALES ApriL______4 I 13 6 26 May______1 3 25 3 _ __ 32 Oc1:ober______June ------4 22 8 -- -6 40 November_~ ~___ I~ I~ 2~ ;luly---- c------December ---- 3 5 8 Sugun,,------], nary· el'tem er ------F~bl:uary==:======----Z- ----i- ===:=::: :====: ==:=:== ----OJ Octobc'------2 I 9 November ------I 5 4 ------10 arch ------M 61 U{~:-::======::::~: --- T ~ !_ ~! ======It TotaL. ------13-9S--52---6----7-178

TABLE 5.-Comparison of Ihe lenglk-freqltrncies of Katsuwonus pelamis al several stagt'S of gOilad d''1Jelopmelll, taken in Philippine and AIarshal/ l.rlands i(/aurs 1

Immature Ripening Ripc Spawning Spent

Mar- Mar- Mar- Mar- Mar- Mar- Mar- Mar- Phil- Mar- Phil- Phil- Mar-I Phil- Phil- Phil- Phil- Phil- Phil- Phil- Length in shall shall ip- sy:!l. !p_ shall shall shall ip- shall ip- shall shall ip- shall millimeters ip- !p~ Is- ip- Is- ip- Is- Is- !p- Is- Is- Is- pines pines pInes Is- pines pines pmes Is- pines pines I.nds pines lands I.nds pmes I'Dds lands lands lands I.nds lands lands

Fe- Fe- Male Male Fe- Fe- Male Male Fe- Fe- Male Fe- Fe- Male Male Fe- Fe- Male Male male male male male male male Male male male male male -----1------_·_----- 3400iJ09,I~~~_~_~_~_~ ~:~~~_ ~:~~~: ~~:~~~ :~:~i~ ~~~~~~ ~~~~j~ ~~~~~~ ~~~~~~ ~~~:i~ ~~~~~~ ~:~~~~ m~1~ :~~~~~ _~:~~~ ~:_~~~ ~~~~-~ ~-m_ ~~~~~: -m~~ _:_J I I 410-419 ------6 ------i------'j------I 420-429430-439 .___• -.------1II 62 ------52 4 2 ----1-. 2 ------1I -----i 440-449______2 2 • 1 5 6 4 I 3 _ 2 1 450-459______I I 4 ------3 Q, 3 4 3 ----j- ---T ::::.: ==::== ==:=== I I 460-469 .___ I 6 II 7 5 8 4 2 1 I I 2 470-479 .___ 1 1 6 5 2 .\ 6 1 ._____ 1 480-489______II 7 4 7 3 I I 2 I 490-499______I I 9 3 6 2 Ii 2 I 2 500-509 .___ 1 7 3 '8 3 I 3 51(1-519______2 .__ 10 7 2 4 2 5 52(1-529______I 3 5 5 3 53(1-539 • -- --_. __ -_____ 4 I 5 6 • 5 54(1-549 .__ 3 5 4 I I 2 550-559 ._ 2 3 2 I 2 3 560-569______I 7 2 I 2 3 570-579 ._ I 3 4 3 2 ~::::: :::::: :::::: ---T :::::: I 580-5S9 -_____ 2 1 5 1 3 590-599______I I I 1 ._ I 600-609 • --____ I I 2 ______620-629610-619 ------• ------.------__ ------_____ ------12 3 ----i- -i3 -- -I =:--== :---=: ::=:-: ---T ::=:== ---T ------_ 630-639 • --____ I 2 I __ _• 640-64-9 ------__ 1 2 I ::__ :: :_:::: :::=_: :::::: ::=::: :::=:: ::::== 650-659 ------__ 4 6 _ 660-669.______I• ------6 2_ 670-679 •• ---- __ ------_ 3 -_. • ::::_: ::::~: :::::: :::::: :::::: ::=::: :::::: -----i 680-689 • ------_ 9 I 690-699 •------6 1 - _ ~r8=m======I~ ====~= ====~l======Total. __======5======3======1======3 13 ======13 ======17 ======1 ======95 ---.!-97 ==:=::78 45 ======52 ======3======8======1======6 1 44 ======9 t Length-frequency data OD Marshall Islands specimens taken from Marr (1948). 418 FISHERY BULLETIN OF THE; FISH AND WILDLIFE SERVICE

TABLE 6.-Localit'Y, length, sex, degree ofmaturity, and gonad weight TABLE 6.-Locality, length, sex, degree of maturity, and gonatl ofKatsuwonus pelamis taken in Philippine woln'J by th, Spencer weight of Katsuwonus pe1amis taken in Philippine waters by the F. Baird, October 1947-NofJember 1948 Spencer F. Baird, October 1947-NofJember 1948-Continued

Fork Fork le!'gth Degree 01 Gonad le!'gth Gonad Date Locality In Sex weight Date Locality m Sex Degree of maturil}" maturity weight milli- in grams milli- in grams· meters meters

1947 1948 Sulu Archipelago____ Male______Unknown____ Male______Ripe______Dec. II _____ do_____ •______540 86.0 Apr. 16 Sulu Archipelago____ ~99 57. ;­ II 505 Female_____ Ripe______168.2 16 _____ 00___ • ______do______. __ do______do. ______• __ ._ ___ do____ • ______do ____ . ___ . ____ 512 __ • __ do______56. 5 II ~85 Unknown____ 90.5 16 515 Female_____ 64. 5 II _. ___ do_____ •_____ ,_ 500 ._.do______Ripe______119.9 16 _____ do ___ • __ • ______Male______do______• ___ do. ______• __ Male__ •______do ___ ••______50S _____do______69. 1 II 502 Uknown. ____ 68.5 16 ~94 Female__ • __ 45. 1 __ ___do______~95 ___ do______Spawning______do______•____ Male______II __ • __ do ______• ____ 77.2 16 504 Spawning____ 81. 5 II 512 ___ do______do. ____ • 51.2 ____ .do___ • ______• Female______do______• __ do ______16 _____ do ___ • ______509 58. 2 II ~91 Female____ • Ripe______126.1 16 Male______Ripe______~8. __ • __ do. ______Male______. ___ do ____ • ______520 _____do______1 II _____ do ______475 Spawning___ • 59.3 16 ~9O Female_____ 7.1. o II ~90 ___ do_____ ._ __ • __ do_____ • Male______do______.do____ ••______do______• __ do______40.5 Apr. 19 Basilan Island, Sulu 488 40. 8 II 500 74.5 Archipelago. II ____ .do____ • ______490 ___ do___ • ______do______do___ • _____ • ______do.______do______• __ .do______do______do______71. 0 19 _____ do______510 ___ do______~2. 2 Dec. 12 479 64.7 19 487 Spawning____ 51. 6· ____ .do______~97 Female____ • Unknown______do ___ • ______do_____ ._ Ripe___ • ____ 12 Ripe______90.0 19 490 59. 1 12 _• ___ do ______.,_____ 510 Male______• 72.0 19 _____ do______Female______._do_.______do______do______do___ • ______520 _____do______117. 2. 12 5n Sp3l\"ninR____ 7~.0 19 ~83 ___ do ___ ---- 86. 3 Dec. 13 ____•do____ • ______498 __ .do______Unknown____ 32.0 ____ .do______Male__ •____ . _____do______do___ • ______do______•• __ do______Apr. 20 513 _____do. _____ H. 5 13 462 18.5 Apr. 21 West coast of Zam- ~85 Female_____ 64. _____ do______. ~85 Fem.le______• ___ do._____ o 13 __ • __ do______• ______39.0 boanga Peninsula. 13 ~82 M.le. ______Ripe____ • ______.do______Male______Ripening______do___ • ______40.0 21 _____ do ___ • ______• __ 564 36. 6 13 ~84 Female_____ Unknown____ 57.0 21 H2 Female__ • __ Ripe______do______Male•• _____ Ripe___ • ______do______• __ __ .do.______do______91. 5 13 __ ___ do_____ •______517 54.0 21 514 10~. 0' 13 465 Female_____ Unknown____ ~8.0 _____ do______• _____ MaJe__ •••__ _. ___ do______do______. ______Male.______do ______21 505 _____ do______~8. 2. 1.1 ~ 12.0 21 • ____ do_____ • ___ • ___ 527 Female_•• __ 83. 3 ___ do____ • __ Spawning____ Luzon Island______do___ • ___ Dec. 15 Zamboanga. Minda- 521 63.0 May 4 560 ___do______Ripening____ 177. 5 nao. May 6 West Coast of Zam- 510 Spawniog___ ... 8l 1948 _. ___boangado______Peninsula. 7 West coast 01 Panay_ 510 ___ do______Rip~ning---- 65.5 M.le____ • ______do______ian. Ripe______6 534 Ripe______50. 3 eb. 23 Mora Gulf, Minda- 5~5 Female_____ 110.0 May 9 Basilan Island, Sulu 549 ___ do_. __ • __ 71. 5 nao. __ •Archipelago.__ do______do____ • ______do______Feb. 25 Celebos Sea _____ • ___ 446 Unknown.___ 9 516 ~9. -M;i;.~~~~== Ripe______----5i~6 ___ ._do______• ___ do____ • ______do•• ____ 5 Feb. 26 Davao Gulf. Minda- 490 9 491 ~2. o oao. • _. __ do______._ Female_____ Ripening______.do__ • ______. ______do______9 476 38. 5 26 ~58 Spawning____ ~1.4 9 ___ ._do. ______508 Male______Ripe______32. 6 _____ do____ • ______~73 ___ do__ •___ • _____ do______7O.~ _____ do_____ • ______Fem:lle_____ 26 _____ do______9 460 Spent.____ ._ 23. 7 26 463 Fem.le_____ Ripening____ 76.0 9 ____ .do______493 ___ d,-.. ______Ripe_____ • __ 77. 1 Feb. 27 _____ do______513 M.le______do____ ._ 19.9 _____ do______._.____ _._do______• ___ do__ ._._ •____ do______• ______do. ____ •______do______9 _____ do______535 ___ do______37. 7 Feb. 29 429 33.4 9 541 _____ do___ •• _ ~5. 2 _____ do______Fem.le______•___ do•• ______do ______• __ ___ do______Spent______29 441 _____ do______56.1 9 ~9O 38. 7 Mar. 3 Celebes Sea ______._ 445 _._do______53.5 ___ ._do______• ____ _._do______Ripe______do______do. _____ • _____ do____ ._ 9 _____ do______.,_ 500 35. 8 3 ~38 37.0 9 ~85 ___do. ___ • __ Spent______34. 5 3 ____ .do____ • _____ • __ 461 Male______Ripe______• 39.0 _____ do______• __ Male______Ripening______do______._ ___ do.______do______9 _____ do______• ______495 27. 3 3 _____ do______431 2.1.0 9 510 Female.____ Spent___ • __ • 22. 7 Female_____ Ripening______do ______Male______Ripe______Mar. 8 _. ___ do______._ 425 _____ do______31.2 9 468 16. 6 MaT. 9 -131 ___ do.______40.0 ____ .do___ • ______do______do______. ___ do______Male__ •____ 9 ____ .do__ • __ • __ . ____ 467 _._do______do______12. 7 9 -155 Spawning._._ 73.0 9 ~71 17. 8 _____ do___ • ______do.______• ____ do______~8.5 Female_____ Spawning____ 9 _• ___ do______• ___ 453 ___ do______Ripe______May 10 Sibuguey Bay, Mora ~98 60. 9 9 _____ do___ • ______437 32.0 Gull. 9 -139 ___ do. ______Spawning__ •• #.0 ___ ._do______Male____ • __ Ripe. ______.do____ . ______._do______Ripe______10 #5 _____ do______17. 5 9 438 55.0 10 _____ do______#1 _._do__ • ____ 17. 7 9 • ____ do___ •_•______435 Female•• ___ Ripening____ ~7.0 North Moro GuIL______do____ •______do. __ ._. _____ do______Male______Ripe______May 11 ___ ._do __ • ______498 29. 8 9 _____ do ______-152 40.0 11 500 Fem.le_____ Spawning____ 32. 5 9 461 • __ do______Spawning.______• _do __ ._. ______Male______Ripening______do______63.0 11 _____ do__ • ______449 15. o Mar. t.l West coast 01 Panay_ 582 Female_____ 142.0 11 438 Female••______do_____ • 22. 1 13 _____ do ______• _____ 569 Male______Ripe____ • ___ %.1 ___ __ do______Male_ ••____ Ripe_. ___ • ______do_. ______• ______do______do__ • ___ II _____ do __ • ______429 IS. 2 J.l 567 52.2 11 459 Female_.___ Spent______29. 5 13 ___ • _do ______546 Fema1e_____ SpenL______~9.2 _____ do __ • __ • ______Male.______Ripe______M.le______11 __ __ .do__ •• ______449 12. 4 Mar. 19 Verde Island Pas- 528 Spawning____ 52.0 11 447 Fem.le_.___ Spent._.____ 22. 4 sage, Luzon. 11 ___ • _do ______• _._ 413 Ma1e______Ripe______29. 7 _____ do ______Female______.do______Female.____ Spent______19 531 ___ do______(f.I.5 May 12 Olf Cotabato Prov- 436 26- 9 ApT. 6 North Sulu Sea______607 Ripe______104.6 _____do _• ______Malc______do______ince.do______Mindanao.• __ • 6 630 76.6 12 ~22 Male___ •___ Ripe______33. 2 6 _____ do______573 ___ do____ ._. Spawniug______uo ______• :Femalc. ____ Spcnt______do______89.5 12 _____ do______402 12. 5 6 592 Female_____ Ripe. ______97.0 12 386 Male___ • ___ Immature ___ 8 _____ do ______._. __ • ___ do______do______do______• _____ Female_____ SpenL __ • ___ 6 _____ do ______;75 76.8 12 419 22: 4 6 585 ___ do. ______do______85.2 _____ do______Male___ • ___ Ripening______do______• __ do_____ • 12 388 8. 3 Celebes Sea ______do____ . _. ____ a_ Apr. 10 __ ___ do ______• ____ 495 ___ do______48.5 12 357 (1) Immature___ 1. 5 Apr. II 422 SpenL______• _do______~93 Female_.___ Ripe_. ______do ______15.6 12 ___ do______do______90. o 11 361 Mal.____ • __ Immature~ _. 3.0 12 _____ do_. ______490 70. _____ do ______.do______• _____ do______Male•• _____ o 11 382 ___ do______3.9 May 14 Davao Gull, Min- 576 Spawning____ 70. 2 11 _____ do ______3n _____ do____ ._ 1.1 danao. • ____ do ______S7S Femalc______do. ______. __ do______Female______.do______11 _____ do ______._do______i.O 14 _____ do______568 92. 5 Apr. 13 469 Ripe__ • _____ 51. 6 May 15 463 Male______Ripe______37. _____ do ______Male___ .•__ •. ___ do______. ____ do______do___ • ______. do______o 13 _____ do ______500 ___ do______28.9 15 484 38. 5 13 ~60 Unknowll____ 20.0 15 __ ___do___ • ______471 Female_.___ Spent______52. 9 _____ do ____ . ____ • ___ -150 ___ do______do______• _do. ______._ __ do______._._do______13 __ . __ do______._ ___ do______16.0 15 __ __ _do______460 58. 1 J.l 4-19 Spawning____ 27.9 15 477 Male___ • ___ Ripe______58. 3 • ____ do______Female•• ___ Ripe______do __ • ______• ___ do______do______13 _____ do______H8 44.5 15 475 46. 3 13 390 Male______Immature______do ____ • ______._ ___ do______do______.1.0 15 __ __ _do______• _____ 473 36. 2 Apr. 15 445 Female_____ Ripe______52.5 15 455 Femal._____ SpawninS____ 66. 5 ('~t,~;~_"::::: __ .d....J ______do______do______• ___ Male______Ripe______15 _____ do. ______426 36.5 15 _____ do. ______#0 26. ~ 15 469 Male______Spawning____ 45.5 15 489 ___ do_. ______do______43. 6 _____ do______de' _____ ._ Ripe______do______do___ • ______do______Apr. 16 495 ___ do______31.0 15 433 17. 7 16 ____ .do•• ______._do______Celeb., Sea______do__ ••______do______• _do ______520 ___ do______58.7 May 16 _____do______436 ___ do______.do______31. 2 16 ~93 Spawning____ 34.3 16 ~12 18. 2 SPAWNING OF PHILIPPINE TUNA 419

TABLE 6.-Localit'y, length, sex, d,gree of maturity, and gonad TABLE 6.-Locality, le1/gtlt, SIX, degrel of ·maturity, and gonad wligkt. ofKatsuwonus pelamis taken in Pkilippifll wattrs by the weigla of Katsuwonus pelamis takm in Philippine waters by the Spencer F. Baird, October 1947-NofJember 1948-Continued Spencer F. Baird, OctobIT 1947-NofJ//Ilber 19'J8-Continued

Fork Fork length Degree of Gonad le",gth Degree of Gonad Locality in Sex weight Date Locality In Sex maturity weight milli­ maturity "in grams" milli- in grams meters meten

19f8 Male______19f8 May 16 Celebes Sea______422 Spawning____ 5.0 June 23 Puerto Princeu, Pal- 516 Female_____ Ripe. ______51. o R.ipe______awan.do______M.le______do______May 20 West coast of Zam- 539 Female_____ 94.6 23 519 25. ___ __do______do______do______o _____boangado______Peninsula.• ___ Male______23 _____ do______530 ___ do______do______36. 2 20 547 _____ do______83.9 23 531 32. 8 Female______do______· ____ 00______00______do______May 22 North coast of Min- 584 122.1 23 50S Spent______36. o dore. June 24 West Sulu Sea______584 Female_____ 55. 8 ~ _._do______do______do__ •______Male______Ripe______June .14 Batangas, Luzon____ 505 69.2 24 ___ __do______510 ___ do______41. 2 June 15 East and south coast 456 Male______do______30.2 24 578 Spent.______27. 3 _____ do______Female____ • _____ do______of.doMindoro.______. ______24 580 M.le______Ripe______57. 2 15 481 Female.______do______40.5 25 East Sulu Sea______525 50. o 15 : ___ .do______530 Male___ . ___ Spawning____ 55.4 Juneune 27 North Sulu Sea______563 Female_____ Spent______58. ___ __do ______do______00______• _do ______do______Ripe______5 15 525 53.2 27 540 ___ do______40. 5 Southwest of Panay__ Female_____ Ripe______do______June 16 _____ do______• 575 _____ do_____ 59.8 June 29 Busuanga Islauds. 488 51. 7 16 5.15 _____ do______63.9 China Sea. _____do ______Male____ • __ Spawning______do______do______do______16 _____do______532 ··31.0 29 _____ do______488 ___ do______00______45. o 16 525 Female_____ Spenr______56.7 29 458 66. 5 _____ do ______Male______Spawning______do ______Male______do______16 530 32.0 29 _____ do______468 15. 6 _____ do_. ______.do______do______466 Female______do______16 _____do. ______550 54.1 29 _____ do______Male______00______42. o 16 548 Female_____ SpenL______89.0 29 492 55. _____do_._.______do______do______South Sulu Sea______Female______do______o 16 597 ___do______do______208.5 July 10 _____do______504- Male. ______do______45. o June 18 ZamboaMia Penin- 533 61.2 10 _____00______498 _____ 00______35. 1 Bula, mdanao. 10 508 Female_____ 37. 4 East Sulu Sea______Male______Spawning______do______Male______Spawning____ Ju'!e 19 529 50.0 10 _____ do______510 ___ d,,______46. 8 _____do______. __ ___ do______Ripening.... _... Ripe______19 503 ___do. ______Ripe______32.0 July II _' ___ do______551 ___ do______do______81. 5 June 21 Dumarin Island. Pal- 509 19.0 II 508 _____ do______70. o Balahac Island, 508 ___ do______wan.do ______do______Spent______July 14 Sulu 41. 3 21 _____do ______50S 22.5 Sea. ____ -"do ______21 485 __ .do_. ______._do______32.0 14 _' ___ do______458 Female_____ 63. _____do______Female______do______do______do______do______5 21 _____ do______522 ___do___ . ___ 66.8 14 _____ do______._ 457 Male______50. o 21 499 _____ do______53.4 14 345 Spawning______do______do______do______. _do ______Female_____ Ripe______31. o 21 ____ .do______5.17 ___do______• _____ do______56.5 14 340 Male______33. 5 21 513 82.2 July 17 West coast of Zam- 565 Spawning______do______.do______do______34. 5 21 _____ do______520 94.6 _____boanR'ado_____Peninsula.. ___ . ___ 21 493 Male______Spawning____ 23.6 17 588 Female_____ Ripe. ______98. 5 _____ do______Female_____ Spent. ______do______do______21 __ " __ do______515 ___ ._do______48.4 July 18 _____Westdocoast______of Panay. 528 Male______84. o 21 553 ._.do______56.5 18 516 _____ do______25. _____ do______Male______. ___ do______Sea______do______00______o 21 _____ do______483 26.5 July 27 _____NorthdoSulu______565 ___ do______36. 3 21 516 ___ 00. ______Spawning__ ... 31.0 27 554 Spawning____ 43. 6 _____ do______~ ______do___ . ___ Spent______do______do__ •______00______21 547 43.5 27 535 41. o _____do______Female______do______do______Female_____ Ripe______21 _____ do ______538 __ .do______do______63.6 27 _____ do______516 Male______51. 2 21 _____do ______508 51.0 27 540 ___ do______Spawning___ • 37. o 615 __ .do______do.______. _00 ______do______21 : ____ do ______do______do______83.9 27 _____ do______564 ___ do______do______67. 2 21 _____ do______518 52.3 27 _____ do______SIS ___ do______30. 5 538 ___do______do_____ . 643 _____ do______21 _____ do______do______do______25.8 27 _____ do______100. o 21 486 36.4 27 627 Fem.le_____ Ripe. ______150. 5 _____ do______.do______do______., __ do______Male______Spawning____ 21 580 ___do______do.____ • 58.6 27 615 ___ do______Ripe______94. o June 22 Tubbataha Reefs, 614 82.3 July 29 Zamboanga, Min- 4S1 21. o ____Sulu_do.Sea.______danao.do______do______595 Male______Ripening______do______22 ___••do______76.7 29 _. _. _do ______472 ___do______29. 5 22 615 __ .do______SpenL______82.6 29 476 Spawning____ 32. 5 ____.do______.._do______Ripe______do ______Female_____ Spent______22 _____do ______5:19 28.0 29 500 39. o 22 560 Fem.le_____ Spent______49.0 29 _____ do______. ____ '_ 478 Male______Ripe_____ . __ 32. 3 ____ _do~ ______do______.do______do______22 558 Ripening____ 8.2 29 47S Spawning____ 39. 5 ____ _do ______Male.______Ripe______do______.do______Ripe______22 555 33.2 29 448 _____00______29. o 22 _____.do.•______. _. 553 Female_.___ Spent. ____.______do______Female______do______Ripe______43.0 29 _____ do______• 440 Male______29. o 22 555 Male.._____ 44.6 29 436 Sp.wning____ 18. _____do______Female______do______do__ . ______Female_____ Ripe______o 22 ___ __do______583 ___ do______103.8 29 448 _____ do_____ • 27. o 22 574 SpenL ______50.5 30 Sulu Archipelago____ 45.1 Male______33. 2 . ____ do______do______.do______July · ____ do______do______00______22 _____ do______551 Ripe______46.8. 30 _____ do______416 _____ do______14. 7 22 570 Male__ . ____ 30 452 Fem.le_____ 35. 6 ____ _do______do______do______no _____ do______do______00______22 ____ .do______621 58.5 30 405 67. 7 22 60S Female______do______Northeast ___ do______Ripening______do______do______do______H.l Aug. I coast of 420 14. 2 22 579 ___ do______70.0 Borneo. ___ do______June 23 Puerto Princesa. Pal- 535 Ripe______• 54.1 Aug. 2 Southwest Celebes 431 _____ do______25. o awan. Se•. . ____ do______._ Male______Ripening______do______do______do______23 526 Ripe______30.0 2 · ____ do______401 ___ do______do______11. 8 23 __ ' __ do______509 Female_____ 47.1 2 396 14. _____ do______'. ___ do______do._____ · ____ do______Male______Ripe______o 23 _____do_____ • ______525 Male______do______54.5 Aug. 6 465 ___ do______48. o 23 561 35.0 6 __. _.do..______440 Spawning...__ 28. 5 _____ do ______do______._do______. _.do______Female_____ SpenL______23 _____ do______564 ___ do______36.0 6 442 34. 5 2.1 _____ do______•. ___ do______. ____ Male. ______Spawning~ ___ ,. __ . _do. ______.____ 545 ___ 00______do______60.6 6 440 ___ do______Ripe______28. o 23 565 38.2 Aug. 10 Sibuguey Bay. Moro 519 28. o ____ .do______"_ Female____ • Ripening____ 23 • ____ do______553 ___00______5.1 _____Gulf.do______do______23 546 Ripe______Female______do ______00______00______65.0 10 _____ do______486 ___ do______do______37. o 23 _____ do______566 Male______do______61.0 10 _____ do______521 ___ do______do______66. o .23 _____do______561 ___ do______00______33.5 10 _____ do______488 54. o 23. .530 54.0 10 481 Male.______._do______29. o _____ do______00______Ripening____ Female.____ _. ___ do______23 _____ 00" ______576 30.5 Aug. II _Northeast____ do______Sulu Sea._ 580 87. o 23 Female_____ Sl?ent______Male______do______' __ do______533 R,pe______60.0 11 _____ do______. ______608 ___ do______70. o 23 535 . __ do______74.4 11 5S0 _____ do______67. _____ do ______Male.______00______do______do______. ___ 00______o 23 ___• _do ______SIS ___ ._00______43.0 11 577 ___ 00______00_____ • 65. o 23 507 Female_____ 58.0 Aug. 31 South Sibuyan Sea___ 584: 60. o 420 FISHERY BULLETIN "OF THE' FISH AND WILDLIFE SERVICE

TABLE 6.-Locality. length, scx, dcgrec of maturity, and gonad TABLE 7.-Monthly sum.mary of all spccimens of troll-caught rocigllt of Katsuwonus peIamis takcn in PMlippine roaters by tllc Neothunnus macropterus, taken by the Spencer F. Baird, Octobcr Spencer F. Baird, Octobcr 1947-No'Ocmber 1945-Continued 1947-November 1948

Fork Month rmma-!R!pen-j R'pe s~awn-I S t Un- ~ tal length Gonad ture mg 1 I mg pen Iknown I 0 "Degree of Date Locality in Se", weight . " . maturity I . milli­ .in Rrams mr.t~r8 ALL FISH October _ 1948 November ~_~_~ ~ ~ ~ _ Sept. 4 North Morc GuIL _ 456 Female Spen!.______55.5 December______6 25 1 2 34 Sept. 13 Celebes Sea _ 460 .10 Ripe______43.0 _____ .10 _ 466 .10 . .10______82.0 January_ .______.I I 1 5 IJ _____ .1,, _ February______2 2 13 46S .10 . .10 .__ 49.0 March______2 1 9 12 North Palawan _ 498 .10 Spent __ .____ 54.0 Nov. 4 _.. .10 . __ ApriL______2 11 11 24 4 _____.10 _ 475 Male______Spawning____ 24.0 May______24 4 1 12 41 4 495 Female. Ripe______40.0 P3.1awan~ 510 .10 .10______50.0 June______4 37 6 1 48 Nov. 6 Northeast __ July______2 6 I 14 23 _____ .10_" _ 498 Male______Spawning____ 54.0 6 S25 .10 .10______53.0 Nov. 7 _____East.10coastof Palawan__ Nov. 10 430 Female Ripe______20.0 _____ .1,, _ 410 Male .10______10.0 10 _____ .10 ._ ~Et~~~~~~~~~~~~ ===~~=I---~~- ~~~~~~~~ ~~~~~~I:=:=~t ----!~ 10 417 do .10______6.0 =:=L 10 _. do _ 465 Female .10______30.0 _____ .10 _ 415 Male .10______4.0 TotaL______45 108 15 71 239 10 _____ .10 _ 10 430 Female .10______20.0 South Sulu Sea _ Nov. 13 _____ .10 _ 515 MALES Nov. IS _____ .10 _ IS t~~ ~~~f:~==== ll~:~~~~==== Nov. 20 Northeast Sulu Sea __ 490 ----on18.0 October : • _____ .10 _ -F~;,;~i;,-_~=== -Rip~===::=== 20 __ .10 _ 470 14.0 November _ 20 480 Male .10______10.0 December______.I 14 1 18 SlO Female .10______40.0 Nov. 21 _____Nortb.10Sulu Sea _ January______1 1 2 495 Male______Spawning____ 30.0 ~ ~ Nov. 22 ___ __ .10 _ February A • _ 22 488 Female Ripe______40.0 March______1 1 Nov. 23 West coast of Min­ 495 .10 Ripening____ 40.0 ApriL______2 6 8 doro. May______13 2 1 16 June______3 20 4 27 Jul)"______I 3 I 5 Augus!.______2 8 2 ._____ 12 September______1 2 j The most of the other individuals of this species October . _ in the collection were considered to be ripening. November ~ ~ ~ ~ ~ _ 13 _ Ripening individuals were found throughout the TotaL______25 54 92 year but most abundantly from April through FEMALES August. Only a few ripe specimens were taken in October _ the course of the operations and no spawning or No,·ember _ December______3 11 ._ 14 spent fish were captured. Although the sample is Januar)"______2 :__ 2 not sufficiently adequate to form the basis for con­ ~~:cu;~::=:=====:==== ~ ~ clusions regarding spawning, it appears that as ApriL. __ • "_____ ==:=== 5 =:======:======: =====:: 5 scattered specimens of ripe fish are found over a ru~~:=:======July______1:1I~ 3 ---T ======!64 Augus'.______2 8 10 long period of time the spawning period is an ex­ September______I I tended one. On the basis of the present data the October _ November______3 .3 spawning period seems to be most intense during TotaL______--20 ----54 2 ------76 May, June, July, and August.

TABLE 8.-Lmgth-frequmcy at uvcralstages ofgonad dcvclopmetlt ofNeothunnus macropterusfrom the Pllilippines andthc nortllern Marshall Islands I

Immature Ripening Ripe Spent

Phil- Phil· Mar- Phil- Mar- Phil- Mar- Phil- Mar- Phil- Mar- Phil- Mar- Phil- Mar- Phil- Mar- Length in millimeters ~p- shall ip- shall shall shall ip- shall shall shall shall !p- Is- Is- ip- h- ip- Is- Is- !P- Is- ip- h- ip- Is- pmes pmes lands pines lands pines lands pines lands pines lands pInes lands pines lands pines lands

Sex 1 Male Male Fe- Fe- Male Fe- Fe- Male Fe- Fe- Fe- Fe- male male Male male male Male male male Male Male male male ------J------H(}"'359 _ 1 • _ 360-379 _ 38(}"'399 _ 1 4()()-419 _ 2 42Q-439 • _ 5 :=====--- =====: ======: ======:::=== :===:: :===:= ===:== -N~~-;'- ======None -N:,'-;'- ===:==None =:=:==_ 440-459 _ 7 46(}"'479 • __ 13 48(}"'499 • _ 18 ----1------i- :====: :====: ======::== ::==== ::===: ===:=: ====:: ==:=:= :::::: ::===: :======500-519 _ 10 6 ~ '--T ---T ---T See footnote at end of table. g ======SPAWNING OF PHILIPPINE TUNA 421

TABLE 8.-Length-frequtncy at serJeral stages ofgonad 4roelopment ofNeothunnus macropterus from the Philippines andthe northern l\{arshall "" " Islands I-Continued

Illlmature Ripening.- Ripe Spent"

Mar- Mar- "Mar- Mar- Phil- Phil- .Phil- Mar- Phil- Phil- Mar-" Phil- Mar- Phil- Phil· Phil- Mar- Length in millimeters ip- shall ip- .hall shall shall shall shall shall ip- shall !p- Is- Is· ip- Is- !p- !s- ip- Is- !p. Is- !p- Is- Is- pines pines lands pines lands pmes lands pmes lands pmes lands pmes land. pmes land. pines lands Fe-· Sea 1 Male Male Fe- Fe- Male Male Fe- Fe· Male Male Fe- Fe- Male Fe- male male male male male male Male male male ------1·------"------520-539. •••_._.______6 6 11 1 7 4 1 1 •••• •• ._ • __ • __ 540-559 .______2 16 3 10 10 3 _. __ ._ •• • __ • __ • __ • __ • __ ~~8::~~t::::::::::::::::::::::::: ~_ ~ '-'T ~ ~ "'T : ---.-- ---T :::::: :::::: :::::: :::::: :::::: :::::: :::::: 600-619 ._••• ::::::2 7 5 9 3 • ._. ••• 620-639 •• .____ 6 3- 5 4 __ •• •• ••_.___ 1 640-659 •• __ • --____ 1 1 --··i- 5 6 ----2-- 4 __ ••••__ __ 5 ------• ------_ 660-679_._" • __ • ._____ 5 2 3 3 -1 -2 2 •• •• _ ~ggjn::::::::::::::::::::::::::: ~. ~ ~ 720-739 •••:::::: ::::::._ t2 1 1 ---T ---T1 :::::: ---T••:::::: :::::: :::::: :::::: ::::::_ 740-759_. • .___ 2 1 .____ 1 • • • _ 760-779 • ._____ 2 __ .___ 1 1 1 •. _ 780-799 • • • • • • 2 1 2 • •• __ ._. •_ 800-819. • ••_.__ 1 1 1 •• • __ • _ 820-839 • • .__ 1 1 • •• __ •••• .___ 3 840-859 •• •• __ ._._. • __ ••• 2 __ •• .___ 1 1 • ._. _ 860-879 • • • .___ 2 •__ •• • • __ • __• _ 88lHl99. •• ••• • ._. __ .___ 1 __ •• .___ 1 900-919 •• .__ 1 • •• •• __ • _ 920-939 ~. ._. • • •• _ 2 1 __ •• .___ 1 940-959 • __ •• • •••__ 1 1 • __ • ._. • __ ••__ • _ 960-979__ • ._. • •• •• 1 _

980-999. •• ~ __ • •• • • __ .___ 1 •__ •• •_ 1~11~1!~~~~~~~~~~~~~~~~~~~~~~~~ ~~~m ~~~~~~ ~~~~~~ m~~~ ~~~~~~ ~~~~~~ ~~~~1~ ~~~~~~ ::::~: ~~m~ ====1= ~~~~~~ ~~~~~~ ~~~~~~ ~~~~~~ ~~~~~~ ~~~~~~ l:lgg::l:g~:::::::::::::::::::::::: :::::: :::::: :::::: :::::: :::::: :::::: :::::: :::::: :::::: :::::: :::::: :::::: :::::: :::::: :::::: :::::: ::::::

Hii:}~======1,200-1,219 ======._. ======•• ======••======__======••• ======~~~~~~ ======• __:=====••_======TotaL .____ --71 --25 --76 --20 ---28 ---54 ---12 ---54 ---9 ---13--- 13 ---2--- 0--- 0--- 0--- 0--- 7

I Length-frequency data of Marohalllsiands specimens taken from Marr (1948).

TABLE 9.-Locality, length, StfX, degree of maturity, and gonad weight TABLE 9.-locality, length. sex, degree of fIlaturity, and gonad weight of NE;othunnus macropterus taken in Philippine fualtfrs by the of Neothunnus macropterus taken in Philippine "wattrs by the Spencer F. Baird, October 19.J7-NorJember 1948 Spencer F. Baird, October 1947-NofJtnlber 19.J8-Continued

Fork Fork le~gth Je~gth Degree of Gonad Dellree of Gonad Locality ID Date Locality III Date Sea maturity .weight Se" maturity .weight milli- mgrams milli- 10 grams meters meters

19#7 1947 Dec. 11 Sibutu Passage, Sulu 673 Female__ •__ Ripening____ 131. 4 Dec. 12 Sibutu Passage, Sulu 553 Male____ ••_ Ripening____ 46.1 Archipelago. Archipelago. _. ___ do ____ • ______Male_.______do. ______. __ do ______Female.____ Immature___ 11 _____ do __ ••_. ______• 575 ___ do______do_____ • 21. 9 12 _____ do ______• _• __ 527 4.6 11 520 12.0 12 517 __.do______do_.____ 8.0 _____ do ______•_•••_. ___ do______.do__ • __ • _____ do____ • ______._ Unknown______.do______11 560 • __ do______15.6 12 _____ do______520 2.4 11 __ • __ do ____ • _. _. __ ._ 608 Ripe.______85.9 12 526 Male______do. _____ 8.0 _____ do ____ • ______do______Ripening______.do_. ______•• ___ do______do__ • ___ 11 __ • __ do ______• 601 ___ do______33.0 12 510 5.5 11 601 • __ ._do_____ • 40.0 Dec. 16 Basilan "land, Sulu 596 Female_____ Ripening____ 54.0 _____ do ______• Female_____ 11 _____ do ____ • ______512 Immature___ 8.0 Archipelago. Male______Ripeni ng.______do ______._ _._do.______do___ • __ 11 • ____ do ______700 _._do______• _____do______9".0 16 602 12.0 11 • ____ do_. ___ • ______645 70.0 11 595 ___ do. _____ • _____ do______63.3 1948 ___ ._do_ ._._._._____ Female.______do______Unknown___ Immature___ 11 610 ___ do ______• 9Q.2 Jan. 12 ____SuI".do_.Archipelago_.______583 3.0 Dec. 12 __ • __ do ______568 ___ ._do______52.0 12 612 Male______• Ripe______13.5 • ____ do ______• _'_ Male______• • ____ do______do. ____ •••_. ___ Female.____ Immature___ 12 ___ • _do ___ • ___ • _____ 574 32.5 12 587 6.8 12 523 _._do__ ••___ Immature_ .. _ 3.5 12 _._ ._do_.______••___ 546 ___ do_____ ._ _.___ do_____ • 7.8 _____ do__ • ______• _. Female____ • Ripeninll_. ______do ___ • ____ •••__ •____.do__ •___ 12 _____ do __ • _. ______554 __ .do______26. 5 12 545 Male_._•••_ 4.2 12 575 _••_.do______22.2 Feb. 19 Port Santa Maria, 797 Female.____ Ripening______do __ • ______.do_. ______do______n.l 12 _____ do______612 ___ do______do______74.8 Zamboanga Pen- 12 _____ do ______555 __ • __ do______14.4 __ •insula.__ do. ______do ______12 547 ___ do______48.6 19 785 _____ do.__ • __ 58.3 12 • __ ••do ••______468 __ .do______• _. __ .do______58.5 Mar. 4 Celebes Sea ______604 _._do______• __ do___ • __ 106.0 _____ do ______• Male.______••do______do______do______do____ ._ 12 _____ do. ______546 __ .do.______do______31.5 4 _____do______587 Male______Ripe.______76.2 12 • __._.do______621 66.5 4 ___ • _do ______525 38.0 12 480 Unknown __ Immature___ 2.3 Mar. 8 470 Unknown___ Immature______••do ______Male______• Ripening______do______do______._do•••___ <') 12 ._____ do __ • ______590 _._do______••___ do______38.2 8 _____do______455 ___do______-----_ .. - 12 626 35.7 8 352 _____do______------1 Gonad weight I..s than 1 gram. 422 FISHERY BULLETiN OF THE FISH AND WILDLIFE SERVICE

TABLE 9.-Locality, length, sex, d~gree of maturity; and gonad fueight TABLE 9.-Locality, ltl/gth; ux, degree ofmaturity, and gonad weighi of Neothunnus rnacropterus takm in Philippine wal"! by lhe of Neothunnus macropterus taken in Philippine waters by the Spencer F. Baird, October 1947-Nouember 1948-Continued "" Spencer F. Baird, October 1947-NorJt1Ilber 1948-Continued"

Fork Fork le!'gth Degree of Gonad length Degree of Gonad Date Locality In Sex maturity .weight" Date Loca1ity in Sei: maturity .weight milli- In gram. milli- In grams meters meters

1948 1918 Unknown___ Immature. __ Male___ •___ Ripe______Mar. 14 Verde Island Passage, 480 -----_.... June 23 ___East.docoast_____ofPalawan_• ______828 ___ do ______52.3 Luzon. 23 6H Ripening____ 30.0 • ____ do______453 • __ do. ______do_____ • _____ do ______• __ 683 Female______do______14 _____ do••______do______do______------23 _____ do__ • ______do______do____ ._ 25.3 14 _____ do ______463 _____ do___ • __ ------23 _____do______._ 660 ___do______do_____ : 25.0 14 47~ ___ do ___ • ___ 23 618 10.5 _____ do______do______do______------_____ do______• ______Male______do_____ • 14 482 ___ do______------23 _____ do______650 43.9 14 _____ do. ______473 ____ _do______2.1 662 ___do ______do______.do______do______------_____ do______.do______._do______11.6 Apr. 11 Celebes Sea ______• __ 454 ------23 640 10.0 _____ do______• __ ___ do______do______• ___ do ______do___ ~ ______do______11 450 ------23 _____ do ______657 7.5 _____ do______do______._do______2,1 Female_____ : ____ do ___ • __ 11 449 _____ do______651 Ripe______32.5 Apr. 12 _• ___ do_. ______493 Male______. ___ do______----Tii 23 700 ___do______• 85.7 ____ .do______• _____ Unknown___ _• __ .do______. ___ do ______• Male______do______12 ____ .do______426 ___doc ______• ____ do______1.9 23 ___ __do ______668 _: __ :do______"21.5 12 _____do______433 2.6 23 710 Female:___ • 54.6 Apr~ Female_____ Ripening______do ______• __ ___ do ______Ripening____ 13 _____do______••_ 614 74.4 23 __ ___ do __ • ______622 ____ .do______22.6 13 464 Unknown___ Immaturc___ 1.5 23 656 ._"_do ______86.2 _____do __ • ______do __ ~ ______13 556 Female____ • Ripening____ 61.5 23 7I5 Male______do______32.1 _____do ______• ______do______do____ ~ ______do ___"____ 13 593 Male______31. 2 23 708 Ripe_. ______55.0 __ • __ do ______• __ ___ do______.do______do ______do______Ripening.:. ___ 13 _____ do_. ______558 48.3 23 __• __ do ______697 _____do______17.0 1.l 418 Unknown.__ ImmatuR'___ 1.0 23 656 ___do ______": 14.0 _____ do______do_ ..____ _. ___ do______•_.do______Female______:_do._____ Apr. 14 _• ___ do______492 ___ do __ • ____ • ____ do______2.2 23 __ • __ do______696 ___ do. ______do______37.2 J4 ____ .do______470 _____ do ___ • __ 1.4 23 _____ do _____ • ______613 ___ do ______11.5 14 472 ___ do ___ • __ • 2.0 23 630 ____.do______18.0 ___ __do ______Male_____ •_ ____ .do___ • ______do ______do ______: __ .do______14 477 __ .do______3.8 23 _____ do ____ • ______641 21. 0 Apr. 17 Sulu Archipelago____ 631 Ripening___ • 14.1 597 Male______do__ : ______do ______Female______do______23 _____do ______do______do______11.0 17 _____ do. _. ______630 Male______• __ do_____ : 19.1 23 _____ do_. ______• 627 9.0 17 530 8.5 23 646 Female______:.do______20.0 _____ do _____ • __ ••______do.______do_._. ______do ______• ______Male______Ripening____ Apr. 18 Island______600 7.5 23 ___ • _do __ • ____ • _____ 60+ ___do ______65.0 Apr. 19 Basilan 596 Female____ • ____ .do_.____ 12.4 23 652 Immature___ 4.0 _____ do______• __ ___ do______.do______• _do ______do______Ripening____ 19 665 17.3 23 __ ___ do______700 ___do______do______17.0 Apr. 21 West coast of Zam- 501 Unknown ___ Immature____ 2.3 23 643 18.0 ____ _do••______Female_____ Immature______boangado. ______Peninsula.._ Male______do ______23 • ____ do_. ______• 640 _____do______3.0 21 537 8.1 23 596 Unknown___ _. ___ do. ______• Unknown______do______West Sulu Sea______• Female____ • May 6 526 _____do._____ 2.5 June H _____do______716 Ripening____ ----:in 6 _____ do______521 Male______3.5 682 ___do ______do_. ____ 25.5 ___ do______do______24 __ ___ do___ • ______Male______do______May 9 East coast Zam- 485 2.1 24 _____do______711 10.5 boanga. 24 800 ___do____ ._. ____ .do_____ ~ 60.0 ____.do_. ______478 Female___ •_ ___ ._do______.do______828 ___do______do______9 _____do_. ______do__ • ___ 2.1 24 ____ .do____ • ______do______do______43.0 9 492 Unknown__ 2.0 H 769 40.0 _____do______• _____ Male______• __do.__ • ______do ______Female______do____ ,_ 9 _____ do. ______517 __ • __do______2.1 24 618 ___do______do______27.4 9 517 Female_____ 2.3 June 27 Cuyo Islands, Sulu 683 44.0 _____do. ______do______Ripening____ 9 _• ___ do______769 _____do______103.4 Sea. Male______.do______9 665 Male__ •____ 42.9 27 __ • __ do__ • ______689 _____ do______.. ____ Female______do__ • ___ 60.5 9 608 48.3 12 Southwest Sulu Sea __ 531 Unknown___ Immature___ ------Moro Gulf____ Male.______Immature___ July South Sulu Sea__ • ______do______._do______May 10 _North____ do ______• ___ • __ 531 ___ do______Ripe______3.5 uly 16 ____ .do______• 462 ___do______do______------10 672 63.8 16 457 GuIL____ Female.____ Immature___ Male______Ripening____ ----on May 12 _____EastdoMorn___ • ______• 483 ___ do__ • ___ • ___ ._do______2.4 July 17 West coast of Zam- 550 12 _____ do __ • ______514 Male______._do______2.9 boanga Peninsula. 12 488 2.3 17 _____ do______• _. ____ 518 Female_____ Immature___ 2.5 _____do__ • ______do______.do______Male______Ripening___ • 12 516 Ripening____ 12.0 17 _____do ______554 6.2 __ ___ do__ • ___ • __ • ___ Unknown __ Immature______do______Immature ___ 12 _____ do______418 _____do______1..1 17 ___ • _do ______520 3.6 12 496 Male_____ •_ 2.0 17 522 Female_____ Ripening____ 9.0 ____.do______• __ ___ do______do______do __ •______Unknown___ Immature___ 12 __ ___do______484 _____ do______2.0 17 455" ___ do______------12 507 Female••___ 2.8 Northeast Sulu Sea __ 385 ___ ._do______do______• ______do____ • ______do ______July 27 _____do______do______do______------12 _____ do______491 _____ do______4.5 27 422 12 497 ___do____ ._. 1.6 July 29 Basilan Island, Sulu 531 Female_____ Ripening____ ----ii~ii _____ do. ______Unknown_.' _____ do______12 ___ __do. ______461 _••__ do______2.3 _____Archipelago.do ______• _____ 12 485 Male._____ • 2.4 29 481 Unknown___ Immature_...... _____ do___ • ______Unknown______.do______do ______do______do______------_ 12 409 _____ do______1.9 29 437 _____ do______------_____ do______472 Female______do ______do. ______12 _____ do______.do______do______2.2 29 ___ __ do. ______397 ___do______do______------12 _____ do ______• _____ 497 Male______do______2.0 29 +06 12 487 2.2 29 _____ do______• ___ 585 Male______Ripening____ ----in ___ __ do. ______Unknown __ ._._._do______do______Unknown___ Immature___ 12 _____do __ • ______484 ____ .do______1.4 29 505 ___do______do__ • ___ ------12 503 Female____ • 5.0 July 30 Sulu Archipelago____ 475 _____ do __ • ______.do.______.do______Female_.__ '_ Ripening____ ----4i~i 12 ____ .do__ • ___ • ______512 Unknown_. 1.9 30 532 Male______12 593 Male_._____ Ripening ____ 20.9 30 _____ do ______617 Ripe __ • _____ 42.5 _• ___ do_ ~ ______Unknown __ Immature______do ______Unknown___ Immature___ 12 ____ _do ______505 _____do______2.5 30 ____ .do______451 _____ do______------12 50-! Male_._____ 6.0 30 458 __.do. ______do. ______• __ Unknown ______do______do______do______------12 _____ do ______• ___ 475 ___do______.do______2.3 Aug. 1 Northeast coast of 430 ------_ .. 12 528 2.0 Borneo, Celebes ___• _..10 ____ .. ______Female______do______12 _• ___ do ______492 5.5 • ____Sea.do. __ •______do______do______12 479 Unknown______.do_.____ 2.2 1 459 _____ do______Mal.______• _____ do______West Celebes Sea______do______do______------12 488 ___do______• _____do______1.6 Aug. 3 438 ___ do______do______------May 15 Davao Gulf. Min- 491 1.8 Aug. 4 _. ___do __ • ___ • ______461 ___ ._do______do______do______" " danao. _____do______4 458 ___do______May 22 Mindanao Sea______526 Unknown__ 1.0 4 _____ do ______428 ____ .do______do______._ Male___ • ______do______do ______Female__ •__ Ripening____ ----3~D 22 533 __ .do______• ___do______4.2 Aug. 6 _____ do_.______546 ___do______• __ • __ do______June 17 East Sulu Sea_____ c_ 513 2.5 6 540 29.1 __ • __ do______do______Ripening______• __ do______Male______.do______17 524 ___ do. ______8.2 6 535 ___do____ • __ Ripe______26.2 June 18 West coast of Zam- 520 Immature.. _.. 2.5 Aug. 7 Basilan Island, Min- 58S 40.0 boanga Peninsula. danao. _____do______do_._____ Ripe______do______• _____ Female_____ Ripening____ 18 _____do______732 ___do__ • ____ 65.0 7 516 Male______do______7.0 18 612 Ripening ____ 16. 4 7 _____ do_ • _____ ••____ 563 8.5 Female______do______do_. ______Female______do______June 22 Tubbataha Reefs, 800 47.0 7 _____ do_. ___ • ______536 Male______••___do______7.0 _____Suludo ______Sea. _._do______• ____ do_____ • 7 ____ .do_. ______527 ___do______.do______7.5 22 745 77.2 7 537 5.0 SPAWNING OF PHILIPPINE TUNA 423

TABLE 9.-Locality, lengtk, sex, degree ofmaturity, and gonad weight Ellthynnlls yaito, in all stages of sexual maturity, of Neothunnus macropterus takm in Philippine waters by the Spencer F. Baird, October 1947-November 1948-Continued was noted throughout the period, and was the most abundant species taken during these studies. The Fork sample was not sufficiently adequate to determine length Degree of Gonad Date Locality in maturity weight milli­ in graIns accurately if spawning remains fairly constant meten throughout the year or if a peak or several peaks of intensive spawning occur followed by periods in 1m Aug. 7 Basilan Island, Min- 487 Female_____ Immature_ __ 4. 5 which only a few scattered individuals spawn. On danao. 7 ._.__do _ Unknown do _ 7 de • __ 476 the basis of the available data the former seems likely. 518 Female do______4.0 7 .do _ Male do______3.0 7 .do _ 504 Unknown do • _ The second most abundant species taken was 7 do • 454 ___do do _ 7 •• do _ 502 ___ do de _ Katsuwonus pelarnis. Both males and females in all 7 do_. • 476 ___do do • __ 464 ___do do _ degrees of sexual maturity were taken throughout Aug. 10 Zamboanga, Min- 472 10 danao.do _ the year. The data indicate that spawning of 10 do _ 567 Female Ripening____ 10.5 544 Male______Immature_ __ 4.5 greater intensity occurs during April, May, June, 10 do _ ___ do______Ripening____ 6.0 10 do _ 550 ___do do______6.5 10 do _ 545 ___do do______7.0 and July than the rest of the year. 10 do _ 554 551 ___do do______29.0 The collection of Neothunnus macropt.erus furnished 10 do _ Female • do______10.5 10 do _ 555 573 __ .do do_.____ 13.0 little data on the spawning habits of this species as 10 do •_ UnknowD Immature .... 10 do _ 522 10 • de _ 5S4 Female • Ripening____ 7.0 almost one-half of the fish caught were immature and 548 Male.______Ripe______26.0 Sept. 3 West coast of Zam- 56S ___do Ripening____ 7.0 most of the others taken were in the early stages of N~~j,nMo~~~W~~ Unknown Immature _ Sept. 4 do ___ 454 ___ do do _ ripening. Only a few individuals were taken that 4 do _ 464 ___do • do _ 4 .do _ 481 ___do do _ were classified as ripe and no spawning or spent fish 4 ._do _ 497 __.do do _ 4 do _ 480 ___ do. do _ were caught. Scattered specimens of 'ripe males 4 do _ 460 ___do do _ 371 were taken at random intervals throughout the Sept. 6 Sarangani Island. 543 Female_____ Ripening____ 17.0 Sulu Archipelago. year, and two ripe females were taken in June. 6 do _ Male______Ripe______18.5 6 do _ 555 ___do • do______15.5 6 do _ 552 Data based upon ripening fish and a few ripe indi­ 406 Unknown Immature _ Nov. 16 South Sulu Sea _ 550 Female Ripening____ 14.0 16' do _ ___ do do______16.0 viduals indicate that spawning apparently extends 16 de _ 620 580 ___do do_.____ 11.0 over a considerable period but is most intense during May, June, July, and August. SUMMARY LITERATURE CITED The data for these preliminary observations on KISHINOUYE, KAMAKICHI. 1923. Contributions to the comparative study of the so-called the spawning of tuna in Philippine waters were scornbroid :fishes. Jour. College of Agriculture, Imperial collected aboard the Philippine Fishery Program's University, Tokyo, vol. 8, No.3, pp. 293-475, 26 :figs., 22 research vessel Spencer F. Baird from October 1947 pis. through November 1948. Three species of tuna, MARR, JOHN C. Neothunnus macropterus, Kat,J1two'/tus pelmnis, and 1948. Observations on the spawning of oceanic skipjack (Katsuwollus pela1nis) and yellowfin tuna (Neotkunnus ma.­ Euthynnus yaito, were collected in numbers sufficient croptmu) in the northern Marshall Islands. U. S. Fish and to make several tentative observations relative to Wildlife Service, Fishery Bull. 44, vol. 51, pp. 201-206, 2 their spawning. The gross field method used in tables, 1 fig. determining the degree of sexual maturity, although SCHAEFER, MILNER B., AND JOHN C. MARR. satisfactory for preliminary exploratory studies, 1948. Spawning of yellowfin tuna (Neothunnus macropterus) and skipjack (Katsuwollus pelamis) in the Pacific Ocean off needs considerable refinement before it can be used in Central America, with descriptions of juveniles. U. S. Fish a comprehensive study of the life histories of the and Wildlife Service, Fishery Bull. 44, vol. 51, pp. 187-196, several species. 5 figs. o