CalCOFI Reports, Vol. 30, 1989 - California Cooperative Oceanic ...

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HUNTER ET AL.: SABLEFISH REPRODUCTION CalCOFl Rep.,Vol. 30,1989 4 > *, 3.5 - bg 3- 52 02 2.5- :: 2- E: 1.5- '2 6,. p 1- 0.5 - 0 0 0 Oct 1986 0 Jan-Feb 1987 (no POs) e Jan-Feb 1987 (with POs) 0.4 10 1 4 I I I I I 1 2 3 4 5 6 Figure 8. Relation between mean density of advanced oocytes in the ovary (Y axis) and density of oocytes calculated from the average diameter (X axis). The average diameter is calculated using the votume of a sphere and assuming oocyte specific gravity of 1 .O: For October 1986 data (squares), K = 0.91; for February 1987 data (open circles), K = 0.89; and K = 0.94 for all data combined (he). Inset shows 1987 data in greater detail; solid circles represent ovaries with postovulatory follicles. where R2 = 0.61 (T was deleted as a variable because its contribution to R2 was negligible when diameter was included in the equation). Thus the mean diameter of the remaining advanced stock of oocytes appeared to be a better index of losses of oocytes due to spawning than was elapsed time. Diameter was also a significant variable in the fecundity equation when only the specimens taken in October were considered. The inclusion of diameter as a variable increased R2 from 0.49 for female weight alone to 0.66, yielding the equation F, = 278,114 + 127 W - 317,198 D. We assumed that the ovaries of females taken in October for fecundity estimation were in a prespawning state. That the mean diameter of the advanced oocytes was inversely correlated with fecundity may indicate that some losses due to spawning may have occurred in some of our October specimens. DISCUSSION Sablejish Reproduction Unlike many pelagic fishes such as anchovy, sardine, tunas, and mackerels, the standing stock of advanced yolked oocytes in sablefish is equivalent to the total potential fecundity; in other words, fecundity is determinate. Five lines of evidence support this view. (1) In mature ovaries (mean diameter of advanced oocytes >0.7 mm) a hiatus exists between the advanced stock of mature oocytes and smaller immature oocytes (this hiatus is obvious in our figure 1, and Mason [1984] provides many more illustrations). (2) The standing stock of advanced oocytes declined over the spawning season. (3) The standing stock of advanced oocytes was lower in females having postovulatory follicles. (4) The mean diameter of the oocytes in the standing stock increased over the spawning season. (5) Our estimates of batch fecundity, total fecundity, and numbers of advanced yolked oocytes in hydrated ovaries were consistent with the assumption of determinate fecundity. Two uncertainties exist. Our analysis does not rule out the possibility that more than one stock of advanced oocytes might be developed and spawned in succession during the year. The extent to which the potential total fecundity is realized is also uncertain. However, the low incidence of atretic oocytes in our specimens indicated that the realized and potential fecundity may have been similar in 1987. The total potential fecundity of sablefish from central California was about twice that of fish from Canadian waters (Mason 1984; Mason et al. 1983), 70
~~~ ~ ~~~~~~~ ~ ~~ HUNTER ET AL.: SABLEFISH REPRODUCTION CalCOFl Rep.,Vol. 30,1989 TABLE 4 Summary of Stepwise Regression of Total Fecundity on Ovary-Free Female Weight (W), Mean Oocyte Diameter (D), and Elapsed Time (T) and Analysis of Variance Table for Second Step with Independent Variables Wand D Stepwise regression Step 1 Constant 13785 W 84 2 t-ratio 6.76 D t-ratio T t-ratio S 85664 R2 36.67 2 351992 71.4 7.18 - 263462 -7.08 67260 61.45 3 340087 70.7 6.90 - 248948 - 4.10 - 85 -0.30 67655 61.50 Analysis of variance Source DF ss MS F P Regression 2 5.62 X 10" 2.81 X 10" 62 18
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Cooperative Oceanic Fisheries Inves
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CALCOFI COORDINATOR Gail Theilacker
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COMMITTEE REPORT CalCOFl Rep., Vol.
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~~ ~ FISHERIES REVIEW: 1988 CalCOFl
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FISHERIES REVIEW: 1988 CalCOFl Rep.
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~~ ~ ~~ ~~ FISHERIES REVIEW: 1988 C
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~~~ FISHERIES REVIEW: 1988 CalCOFl
Page 21 and 22: ~~ LO AND METHOT: 1988 NORTHERN ANC
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Page 27 and 28: LO AND METHOT: 1988 NORTHERN ANCHOV
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Page 35: PUBLICATIONS CalCOFl Rep.,Vol. 30,1
Page 38 and 39: SYMPOSIUM INTRODUCTION CalCOFl Rep.
Page 40 and 41: POLOVINA: ARTIFICIAL REEFS: BENTHIC
Page 42 and 43: BUCKLEY: ENHANCING MARINE FISHERIES
Page 48 and 49: MACCALL: AGAINST MARINE FISH HATCHE
Page 50 and 51: MACCALL: AGAINST MARINE FISH HATCHE
Page 52 and 53: RUTLEDGE: TEXAS MARINE HATCHERY PRO
Page 54 and 55: RUTLEDGE: TEXAS MARINE HATCHERY PRO
Page 56 and 57: DAVIS: DESIGNATED HARVEST REFUGIA C
Page 63 and 64: HUNTER ET AL.: SABLEFISH REPRODUCTI
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Page 75 and 76: ~~~ - LAVANIEGOS-ESPEJO ET AL.: EL
Page 77 and 78: LAVANIEGOS-ESPEJO ET AL.: EL NINO E
Page 79 and 80: ~~~~~ ~ -~ ~~ ~ ~~~~ ~ Stylocherrot
Page 89 and 90: ~ . LAVANIEGOS-ESPEJO ET AL.: EL Nl
Page 91 and 92: ~~~ . ~ SMITH ET AL.: ZOOPLANKTON P
Page 93 and 94: ~ 2:48:031 SMITH ET AL.: ZOOPLANKTO
Page 95 and 96: SMITH ET AL.: ZOOPLANKTON PATERN AN
Page 97 and 98: SMITH ET AL.: ZOOPLANKTON PATTERN A
Page 103 and 104: SMITH ET AL.: ZOOPLANKTON PAllERN A
Page 105 and 106: SMITH ET AL.: ZOOPLANKTON PATTERN A
Page 107 and 108: HENDRICKX AND ESTRADA-NAVARRETE: PE
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HENDRICKX AND ESTRADA-NAVARRETE: PE
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HANAN ET AL.: SEA LIONS AND COMMERC
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HANAN ET AL.: SEA LIONS AND COMMERC
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SANZ AND URIARTE: BAY OF BISCAY ANC
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~~ ~_____ ~ SANZ AND URIARTE: BAY O
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SANZ AND URIARTE: BAY OF BlSCAY ANC
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SANZ AND URIARTE: BAY OF BISCAY ANC
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~ ~~~~ LEONG: ANCHOVY SPERM CONCENT
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LEONG: ANCHOVY SPERM CONCENTRATIONS
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AUTHOR-TITLE INDEX, 1983-88 CalCOFl
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SUBJECT INDEX, 1983-88 CalCOFl Rep.
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SUBJECT INDEX, 1983-88 CalCOFl Rep.
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130' 125' 120" 115' 1100 1 I I 1 1
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CalCOFI Reports, Vol. 30, 1989 - California Cooperative Oceanic ...

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