The maturation of Pacific mackerel has never been documented

clearly. Analysis of data reveals spawning can occur from

March through October, but the majority takes place from April

through August. During this April through August period,

22.5%, 65.7%, 75.1%, 84.7%, 84.2%, and 87.5% of the female

fish were mature or maturing for Age Groups I, II, III, IV, V,

and VI+ respectively.

A von Berta1anffy growth curve and a weight-length curve

were calculated. The weight-length curve was found to differ

significantly from a curve previously published. (21pp.

Knaggs, Eric H.

Parrish, Richard H.

English

Aquatic Commons

MATURATION AND GROWTH
OF PACIFIC MACKEREL
SCOMBER JAPONICUS HOUTTUYN
by
Eric H. Knaggs and Richard H. Parrish
MARINE RESOURCES
TECHNICAL REPORT NO.3 1973
CALIFORNIA DE PAR TME NT OF FISH A ND GAME
MARINE RESOURCES TECHNICAL REPORTS
******************************************************
Marine Resources Technical Reports are research
documents by Department personnel that are of sufficient
importance to be preserved, but which for some reason
are not appropriate for primary scientific publication. No
restriction is placed on subject matter.
These Reports may be cited in publication, but care
should be taken to indicate their manuscript status. The
material in these Reports may eventually appear in the
primary scientific literature.
Inquiries concerning the Reports should be directed
to The Editor, Marine Resources Region, 350 Golden Shore,
Long Beach, California 90802.
MATURATION AND GROWTH OF PACIFIC r1ACKEREL
SCOMBER JAPONICUS HOUTTUYN
by
Eric H. Knaggs and Rich~rd H. Parrish
Marine Resources Region
MARINE RESOURCES TECHNICAL REPORT NO. 3
California Department of Fish and Game
1973
ABSTRACT
The maturation of Pacific mackerel has never been documen-
ted clearly. Analysis of data reveals spawning can occur from
March through October, but the majority takes place from April
through August. During this April through August period,
22.5%, 65.7%, 75.1%, 84.7%, 84.2%, and 87.5% of the female
fish were mature or maturing for Age Groups I, II, III, IV, V,
and VI+ respectively.
A von Berta1anffy growth curve and a weight-length curve
were calculated. The weight-length curve was found to differ
significantly from a curve previously published.
(2)
TABLE OF CONTENTS
Page
ABSTRACT-------------------------------------------------------------- 2
ACKNOWLEDGEMENTS------------------------------------------------------ 4
INTRODUCTION---------------------------------------------------------- 5
METHODS--------------------------------------------------------------- 5
Maturation Data----------------------------------------------------- 5
Growth Data--------------------------------------------------------- 5
RESULTS--------------------------------------------------------------- 6
Maturation---------------------------------------------------------- 6
Growth-------------------------------------------------------------- 7
DISCUSSION------------------------------------------------------------16
CONCLUSIONS-----------------------------------------------------------17
REFERENCES------------------------------------------------------------18
(3)
ACKNOWLEDGMENT
This study was conducted in cooperation with the Department
of Commerce, National Oceanic and Atmospheric Administration,
National Marine Fisheries Service, under Public Law 88-309,
Project 6-3-R.
(4)
INTRODUCTION
The biology of Pacific mackerel must be clearly understood to properly
manage this resource. One of the aspects of its biology which has not been
clearly documented in the literature is age at first spawning. Fry (1936)
states that yearling fish do not spawn, whereas most of the 2 year olds do.
Fitch (1952) observed that most mackerel do not spawn until their third or
fourth year.
To clearly document age at maturity, we conducted a special study on
the maturation and growth of Pacific mackerel. This information will con-
tribute to our understanding of the biology and population dynamics of
this fish.
METHODS
Maturation Data
Data concerning 1958-59 through 1969-70 Pacific mackerel seasons
were utilized to determine age at maturity. Information about 3,397
female Pacific mackerel was used in the study. Samples used were taken
as part of a program for monitoring the California commercial mackerel
catCh.
Three maturity stage categories were established. If eggs were not
visible with the naked eye, fish were considered immature (Stage i). If
a fish had unripe yellowish ·eggs visible to the naked eye, it was considered
to be developing (Stage g). Any fish which had large transparent ripe eggs
was classified as mature (Stage G). This maturity index agrees favorably
with that suggested by Holt (1959) for Rastrelliger (Table 1).
Growth Data
Weight-length relationships were determined by using a computer
program (Abramson, 1971) which fits weight-length data to the exponential
(5)
-6-
b
curve: W = a L
where: W = weight
L length
a = constant
b = constant
A computer program also was used to fit Pacific mackerel data to the
von Berta1anffy growth equation: 1t = L [l-exp (-kt+kt )].00 0
where: 1 t
L
00
t
o
k
total length at age t
maximum expected length
fitted length at age zero, extrapolated backward from
growth pattern in later life
a parameter related to the matabo1ic rate
exp= exponential function
This program fits a curve using the least squares procedure with weights
proportional to sample size (Tomlinson and Abramson. 1961).
RESULTS
Maturation
Analysis of data indicates spawning can occur from March through
October, but the majority takes place from April through August. An impor-
tant factor contributing to the great spread in spawning time is that eggs
of an individual fish appear to mature in successive batches. Ripe trans-
lucent eggs appear irregularly in the ovary amongst still unripe ova in
early stages of development. This condition also has been found in Atlantic
mackerel, Scombe~ scombrus Linnaeus, (Steven, 1949) and in the genus
Rast~ellige~ (Holt, 1959).
Only five fish were found in a spent condition during the entire study
and all of these in October. Since eggs mature in successive batches, a
spent condition would not be found in a fish until all spawning was completed.
Due to this fact, we did not include spent condition in our maturity stage
classification (Table 1).
-~
All identification and examination of ovaries was done externally;
therefore, the number of mature fish may have been underestimated. Steven
(1949) found that Atlantic mackerel ovaries containing numerous ripe eggs
in the lumen may show no external evidence of their presence.
Immature individuals were found in each age group throughout the year
(Table 2). No female Pacific mackerel spawn during their first season
(Age Group 0), and only 22.5% of Age Group I fish were found to be mature
or maturing from April through August (Table 3). During this same period,
the percentage of maturation in older age groups was 65.7%, 75.1%, 84.7%,
84.2% and 87.0% for Age Groups II, III, IV, V, and VI+ respectively. It
is not definite that all individuals of any age group spawn in any given
season, and the percentage of maturation is higher during some months than
for the spawning season (Table 4).
We also conducted a study on maturity of male Pacific mackerel; how-
ever, our results should be considered preliminary because of the small
sample size (205). Male Pacific mackerel mature earlier in life than
females and appreciable amounts of ripe sperm commonly are found. No Age
Group 0 males were found to be mature or maturing. During a 3 month period
(May through July), the percentage of male fish mature or maturing was
88.0%, 96.6%, 100.0%, 100.0%, 100.0%, 100.0% for Age Groups I, II, III, IV,
V, and VI+ respectively.
Growth
We processed lengths and weights of 1,232 fish with the resultant
weight-length relationship for Pacific mackerel being W= 0.0000013660
L3.39358. Using this formula, a 270 rom FL fish weighs 243 grams (Table 5)
while a 340 rom FL fish weighs 532 grams. The calculated length-weight
curve is a good fit for the data with the correlation coefficient being
0.994 (Table 6).
-8-
TABLE 1. l'1aturity Stages of Rastre Uiger and Scomber
Extent of ovary
in body cavity
About 1/3 length
of cavity.
About 1/2 length
of cavity.
General appearance of ovary
Translucent; reddish to pink-
ish ova invisible to naked eye.
Translucent; pinkish color; ova
invisible to naked eye.
Raetre ~ lige r '*
Stage and State
I
Immature
II
Mature virgins
and recovering
spents
Scomber
Stage
i
--------------------------------------------------
About 2/3 to full
length of cavity.
From 2/3 to full
length of cavity.
Shrunken to about
1/2 length of
cavity; walls loose.
'* From Holt, 1959.
Pinkish yellow color; granular
opaque appearance; ova entirely
opaque; no translucent or trans-
parent ova visible.
Orange to pink color; super-
ficial blood vessels; conspicu-
ous large translucent to trans-
parent ripe ova visible; eggs
might be extrusable.
Remnants of disintegrating
opaque and ripe ova visible;
may be darkened or translucent.
III
Ripening
IV
Ripe
V
Spent
g
G
-9-
TABLE 2. Monthly Maturity Index of Pacific Mackerel in Percent·
HOT'.th
................_..'~-..
-II-ill IV VI+a I v---------~-
J :111 •
i 100 100 100 95 94 100
g -~,. 5 6
G
Feb. ...
i --- lOa 100 83 78 50 100
g 17 22 50
G
Mar.
i 97 84 50 25 20 34
g 3 16 45 75 80 67
G ..-- 5
Apr.
i 76 28 16 4 5 24
g 21 69 72 91 90 70
G 3 3 12 5 5 6
May
i 78 34 13 2 9
g 22 66 78 82 61 64
G 9 16 30 36
June
i 77 16 25 23 23 14
g 23 82 n 60 77 71
G 2 3 17 15
July
i 72 33 28 18 39 ./
g 28 65 72 82 61. 67
G 2 26
Aug.
i 100 86 76 55 36 17 25
g 14 24 41 if3 44 25
G 4 21 39 50
Sept.
i 100 89 75 54 74 83 56
g 11 25 46 26 17 44
G
Oct.
i 100 99 94 75 87 99 70
g 1 6 25 12 1 30
G 1
Nov.
i 100 100 100 100 96 100 95
g 4 5
G
Dec.
i 100 100 100 100 100 100 100
g
G
-10-
TABLE 3. Maturity Index of Female Pacific Mackerel in Percent for
April Through August
Months Age Group
0 I II III IV V VI+
April-August
i 100 77 .5 34.3 24.9 15.3 15.8 13.0
g 22.2 64.5 69.9 73.1 64.2 64.8
G 0.3 1.2 5.2 11.6 20.0 22.2
Percent mature
or maturing 0.0 22.5 65.7 75.1 84.7 84.2 87.0
Number examined 45 613 318 173 190 120 54
-11-
TABLE 4. Highest Percentage of Mature and Maturing
Stages of 'Female Pacific Maekerel in any
One Month
Ap. Group Percentage Month Number Examined
I 28 Jll1y 137
II 84 Jlm.e 82
III 87 May 46
IV 98 May 44
V 95 Apl'il 20
VI+ 100 May 11
-12-
TABLE 5. Some Expected Weights ·for Given Lengths by 10 nun FL Groupings
Fork Expected Fork Expected Fork Expected Fork Expected
Length Weight Length Weight Length Weight Length Weight
(nun) grams (nun) grams (nun) grams (nun) grams
130 20 220 122 310 389 400 924
140 26 230 141 320 433 410 1005
150 33 240 163 330 481 420 1090
160 41 250 188 340 532 430 1181
170 51 260 214 350 587 440 1277
180 62 270 243 360 646 450 1378
190 74 280 275 370 709 460 1485
200 88 290 310 380 776 470 1597
210 104 300 348 390 848 480 1716
-13-
TABLE 6. Constants and Standard Errors for the Weight-Length Relationship
a
1. 36600E-06
b
3.39358
Standard
error of b
0.01088
Standard error Correlation
of the estimate coefficient
39.04692 0.994
-14-
TABLE 7. Lengths a t Vari DUS Ages
Sample Standard error
Age Fitted length Mean length of sattIple mean Sample Size
(mm FL) (mmFL)
I 272.96 272.44 1.121 349
II 308.34 312.35 1.113 119
III 336.05 334.75 0.789 157
IV 357.75 356.09 0.927 172
V 374.75 375.52 0.675 232
VI 388.05 388.52 1.242 108
VII 398.48 396.80 1.623 57
VIII 406.64 412.27 3.653 11
Standard error of estimate = 14.8762
-15-
TABLE 8. Estimates of Parameters for Von Berta1anffy Growth Curve
Parameters Parameters Metabolic rate Fitted length
Average maximum Average maximum constant at age zero
length cm/4 length mm. k to
Estimates 174.45 436.12 0.244440 -3.0222
Standard
errors 2.10 5.26 0.13694 0.154625
-16-
Traditionally Pacific mackerel measurements have been reported in
quarter-centimeters. To facilitate future workers who may use this
b
measurement with the exponential equation W = a L , the constant a should
be changed to 3.06119E-05 while the constant b of 3.39358 remains the same
number.
The weight-length curve was compared to the curve determined by
D. H. Fry, Jr. (Fitch, 1951). An analysis of covariance was calculated
from the resulting two lines of a log transformation. There was no signi-
ficant difference between the slopes of the two lines; nevertheless, there
was a significant difference in elevations and variation about the regression
lines (all differences at the 99% significance level). The older set of
data showed more variation about the regression line.
The von Berta1anffy growth curve estimate for Age Group I fish was
273 mm FL (Table 7), while the estimate for Age Group III was 336 mm FL.
The maximum expected length (L ) was calculated to be 436 mm FL (Table 8).
00
These estimates are derived from data taken throughout the season and
represents mean size at midseason for each age group.
DISCUSSION
Population size may account for the relative rate of growth. Davidson
and Vaughan (1941) suggested that more abundant populations of pink salmon,
Oncorhynchus gorbuscha (Wa1baum), are slower grOWing. Witney (1961) found
that growth rates of bairdie11a, BairdieUa icistius (Jordan and Gilbert),
in the Salton Sea, California, decreased as the population increased.
MacGregor (1959) found that low population levels of Pacific sardine
are associated with high condition factors and, conversely, high population
levels are associated with lower condition factors. The inverse corre1a-
tion was interpreted as a cause and effect relation; that is, high popu1a-
tion levels result in less available food per fish and low condition
-17-
factors, while low population levels result in more available food per fish
and higher condition factors.
In Pacific mackerel, the population decreased in biomass from a high
during the 1931 to 1933 period to a low during the 1966 to 1970 period.
The estimated total biomass for I year-old fish and older during the 1931
to 1933 period ranged from 1,040,519,000 to 1,593,966,000 pounds. The
total biomass estimates for the 1966 to 1970 period ranged from 6,728,000
to less than 1,101,000 pounds. If at this later period there was a decrease
in the competition within the population, then certainly the weight at size
could increase.
A comparison was made between Murphy method estimates of recruits at
age I and mean size at age I for twenty-nine consecutive years. The
results show little correlation between estimated numbers of recruits and
mean size at age I (r = -0.208).
Witney (1961) found that bairdie11a matured later in life as the popu-
lation increased and growth rates decreased. In Pacific mackerel, if growth
by weight at size has increased, then this may account for the apparent
increase in maturation at an earlier age.
The two studies were done over 30 years apart. An environmental or
growth change may have occurred; however, the true reason for these apparent
changes may be based on the manner in which the data was collected. The
older data was collected only intermittently during the study period,
while the newer set of data was collected throughout the year.
CONCLUSIONS
Most female Pacific mackerel (65.7%) are mature or maturing by their
third year of life (Age Group II). The percentage of fish maturing con-
tinues to increase from age at first spawning until Age Group IV where it
levels off at a high percentage of fish maturing within a spawning season.
-18-
The Pacific mackerel sampled during the 1966 to 1970 period had a
larger mean weight at size than those fish sampled from 1931 to 1933.
Fish sampled from 1958 to 1970 also appear to mature earlier in life than
those caught during the early years of the fishery.
REFERENCES
Abramson, Norman J. 1971. BGC 2 - von Bertalanffy growth curve fitting,
2.(-).1.1-1.3. In Computer Programs for Fish Stock Assessment.
F.A.O. Fish Tech. Paper (lOl):V.P.
Davidson, F.A., and Elizabeth Vaughan. 1941. Relation of population size
to marine growth and time of spawning migration in the pink salmon
(Oncorhynchus gorbuscha) of southeastern Alaska. Jour. Mar. Res.
4:231-246.
Fry, Donald H., Jr. 1936. A preliminary summary of the life history of
the Pacific mackerel. Calif. Fish Game 22(1) :30-39.
Fitch, John E. 1951. Age composition of the southern California catch of
Pacific mackerel, 1939-40 through 1950-51. Calif. Dep. Fish and Game,
Fish Bull. (83):1-73.
1952. The decline of the Pacific mackerel fishery. Calif. Fish
Game 38(3):381-389.
Holt, Sidney J. 1959. Report of the International Training Center on the
Methodology and Techniques of research on mackerel (RastreZZiger).
F.A.O. Report, (1095) :1-129.
MacGregor, John S. 1959. Relation between fish condition and population
size in the sardine (Sardinops caeruZea). u.S. Fish Wild. Serv.,
Fish. Bull. 60(166):215-230.
Steven, G.A. 1949. Contributions to the biology of the mackerel Scomber
scombru8 L. II. A study of the fishery in the southwest of England,
with special reference to spawning, feeding, and fishermen's signs.
-19-
J. Mar. Bio1. Assoc. U.K., 28:555-581.
Tomlinson, Patrick K., and N. Abramson. 1961. Fitting a von Berta1anffy
growth curve by least squares including tables of polynomials. Calif.
Dep. Fish and Game, Fish Bull., (116):1-69.
Witney, Richard R. 1961. The bairdiella, BairdieZZa ioistius (Jordan and
Gilbert):105-l5l. In The Ecology of the Salton Sea, California, in
relation to the Sportfishery. Calif. Dep. Fish and Game, Fish Bull.,
(113):1-204.


Maturation and growth of Pacific Mackerel, Scomber japonicus Houttuyn

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Maturation and growth of Pacific Mackerel, Scomber japonicus Houttuyn

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