Allometric Growth in the Striped Marlin, Makaira mitsukurii, from New Zealand'
JAMES E. MORROW, JR. 2
INTRODUCTION of a size commonly taken on rod and line. The world 's record for striped marlin is 409 MEASUREMENTS MADE on 49 striped marlin centimeters in total length (about 325 cm. in obtained by the Yale-New Zealand Expedi standard length), and marlin less than about tion, 1948, are the basis for this study. The 150 centimeters are rarely if ever taken on rod fish were caught on rod and line between and line. Since our specimens range from January 31 and March 3, 1948, near Cape 201.9 to 286.5 centimeters in standard length, Brett, New Zealand. The majority (36) were we are thus dealing here neither with the taken in the immediate vicinity of Cape largest nor the smallest, but r~ther with the Brett, at the mouth of the Bay of Islands, middle portion of the adult SIze rang~ . while the remaining 13 were caughtnear the Studies of allometric growth are applicable Cavalli Islands, about 20 miles to the north to a number of broad problems. They may west. Thirty of the fish were caught by mem help to elucidate the laws governing the bers of the expedition. For the privilege of growth of animals and establish general examining the remaining 19, it is our pleasant principles of wide applicati?n. The~ ~ay duty to extend our thanks to the guests' of provide a clue to the ~echamcs ~f raciatron, Otehei Lodge, Otehei Bay, New Zealand. speciation, and evolution; changing grow.th We also wish to thank the proprietors, Me. patterns, both ontogenetic and phylogenetic, and Mrs. G.]. Hassall, and their staff for their are indicators that these phenomena are tak generous co-operation and for the .excellent ing place. They may indicate whether or not working facilities which they furnished us. a widely ranging species is homogeneous or The fish measured in this work ranged be composed of a number of separate popula tween 201.9 and 286.5 centimeters in standard tions, information which is often vital to the length. This is, then, an examination of all ~ fisheries biologist or conservationist. It was metry in adult animals . Ideally, a study ofthis with particular reference to this last point that type would include specimens from the the measurements here recorded were made. smallest postlarva to the largest adult, thereby These measurements should be especially providing indices to the growth patterns at valuable to workers who gather similar data all ages and showing when and how these on this species in different parts of the world . growth patterns change. Because of the methods of capture available to us, however, MATERIALS AND METHODS we were unable to do more than examine fish All big-game fish brought in to Otehei Bay lScientific results of the Yale-New Zealand Expe- were weighed on the official scale of the Bay dition, 1948. . of Islands Swordfish and Mako Shark Club 2Bingham Oceanographic Laboratory, Yale Uni versity, New Haven, Conn . Manuscript received by G. ]. Hassall, weighmaster. Linear meas December 26, 1950. urements were made by us with a tape
[ 53] 54 PACIFIC SCIENCE, Vol. VI, January, 1952
graduated to Y-i inch and read to the nearest double logarithmic scale and regression Va inch. For convenience in calculating, equations were fitted by the method of least inches were later converted to centimeters and squares. The significance of deviations from pounds to kilograms. These converted mea isometry was tested by methods outlined by surements are listed in Table 1. It may be Snedecor (1948: 103-168) and Simpson and added here that measurements made with a Roe (1939: 186-284). Comparisons of k tape are not completely satisfactory.: As a values followed the methods of Snedecor result of this experience, we suggest the use (1948: 318-339) and Simpson and Roe of large calipers, which can be laid parallel (1939: 277-280). The standard length was to the long axis of the body and the arms of always measured along the central axis of the which are long enough to encompass the body from the tip of the sword to the center greatest depth of the animal. In this way, of the notch on the caudal peduncle. Other accuracy will be greatly enhanced. measurements are described in the appro Throughout this study, use has been made priate sections. of the logarithmic growth equation, Y = There appears to be but little data in the bXk, or log Y == log b-l-k log X, where literature on allometry in the striped marlin. Y = length ofbody part, X = standard length, Gregory and Conrad (1939: Table 1) give b = initial growth index, k = equilibrium con detailed measurements of 17 specimens stant (Huxley, 1932: 4-8; Huxley and Teissier, (standard lengths from 250.8 to 284.0 crn.) 1936: 780). In the use of this equation, k = 1 from Cape Brett, N. Z., and nine specimens indicates isometry, with the portion under (standard lengths from 203.0 to 286.0 cm.) consideration increasing in size at the same from Mayor Island, N. Z. Shapiro (1938: rate as the standard length. Similarly, k greater 1-20) has examined growth patterns in the or less than 1 indicates positive or negative blue marlin (Makaira nigricans ampIa) of the allometry, with the body parts increasing at . Atlantic from 195.0 to 304.0 centimeters in a greater or lesser rate than the standard standard length. Where appropriate, .we have length. Note also that the units of the body compared the patterns shown by our sample parts are not necessarily equal to the units of with the data given by these authors. the standard length, but are related to them through a factor represented by the constant GROWTH PATTERNS b. Thus, if X changes by 1 meter and Y changes by only 1 centimeter, then k = 1.0 The Length-Weight Relationship and b .=0.01. In the vast majority of fishes which have With respect to the length-weight relation been examined from this standpoint, the ship, it should be noted that weight is equal equilibrium constant of weight on length is to density times volume. Since volume is the approximately 3. However, wide variations resultant of three dimensions, length, breadth have been recorded, from as low as 1.4 (Hile, and depth, the length-weight relationship is 1936: 243) to over 3.9 (Shapiro, 1938: 5), in thus a cubic rather than a linear one. Isometry various species. Indeed, comparable variations of length and weight, therefore, must be are to be found between different populations indicated by k = 3. In the same way as before, of the same species (e.g., the cisco, Leucich k greater or less than 3 indicates that weight thys artedi, according to Hile, varies approxi is increasing more or less rapidly than the mately from 1.4 to 3.7. Although sampling cube of length, and also shows that the three errors may often account for a large portion linear components of weight do not vary at of the deviations in this relationship (Mor the same rate. row, 1951: 20-22 ), real differences in the Each set of measurements was plotted on a length-weight relationship undoubtedly in- Growth in Striped Marlin-MoRROW 55
TABLE 1 M EASUREMENTS OF STRIPED MARLIN E XAMINED AT OTEH EI BA Y, BAY OF I SLANDS, N. Z.*
Ul Z ~ z ~ Ii: ~Ii: ~ .... Ii .... Q .... -c .... <: ...... z ~ ~ ... Q <: Q < <:I: sa Ul I-< <: :I: Q:I: .... ~ ~ ~ o ~ ~ I-< :::;
· Weight in kilograms, other measurements in cennrnerers. 56 PACIFIC SCIENCE, Vol. VI, January, 1952 dicate different growth patterns, either be 'O 0 ....-4 0 0\ 0\ ~ rf'\ ....-l ++ ~ rn~ ('(') rn N \f"\ ...... ~ N O tween species or at different times or In '" l 00 00 0 0 0 00 different populations of the same species. r---oo~ ...... O\ ooO\ ...... rn O \f'\ V"\ ,""",N Ci\N O~ The sample of striped marlin considered O ooll"\\O O\O\ O\ r-oo here has a length-weight equilibrium con ""';00000000 stant of 3.009. However, the standard error * Q ofk, Sk is 0.307, indicating the possibility of Z ..: ...... V'\ O ...... \ON ~ N In ...l '<:t'N NN NN NN ...... rather wide random variations k which -c 00 0 0 0 0 00 0 >< 000000 000 would not be significant. Shapiro (1938: 5) N'" o reported the equilibrium constant of weight ~ · 0 '" d on length for the Atlantic blue marlin as 3.93 Z 11- '"- --+------ :=o * for a sample of 23 specimens. The difference 0:: ~ o '<1'0\ '<1'000\\0000\ '" is quite reasonable, for the blue marlin is a O N ~ """" \f"\ N O\\f"\ "d' ""Z \ o ...... V"\ t--- «"'I OO O\ N O\ OO ::l ...l \O OOO ...... l'f"\ '<:t' ...... \D 1I"\ much deeper-b odied fish. It is probable that 0:: ("(")f"C"'l....-.l N Ml ("(") N"'\ ...... N ..: 000000000 the Pacific black marlin (Makaira nigricans ~ 000000000 mar/ina) might have an even higher constant . Q The white marlin (Makaira albida) seems to ;;;'""" 11--.."..-- ;.------1 I-< to be a very slim fish and ought to have a con en ~ Z o siderably lower constant in its length- weight o o d equation. en to Linear M easurements >< o o Statistics of the logarithm ic regressions of d en the various linear measurements are given in Table 2. Significant departures from isometry ;:iz g>< I were found in only two of these measure :=- ...l ments , although two others , pectoral length z >< ..: '" "0 on standard length and dorsal fluke of the :=- ...l I tail on ventral fluke, approach a significant z level. It is possible that examination of larger I samples might show the allometry of these dimensions to be significant. I-< The length of the sword , from the tip to ~ >< Q • the anterior margin of the eye, maintain s an z 5 isometric relationship to the standard length. '""" ..:'" Q'" -0:: The data publi shed by Gregory and Conrad "o ..:;> (lo c. cit.) give values of k of 0.816 for 17 fish ...l from Cape Brett and 0.889 for 9 fish from Mayor Island. Shapiro (1938: 15) gives k = 0.88 for the sword of the blue marlin. None I-< of these figures represent a significant de Z Cl >< parture from isometry. This IS somewhat Z .". surprising, for it is popularly assumed that '" ...l '"""Q ..:'" the sword tends to become relatively shorter Z 0:: -..: with increased overall length . o" ;> ...l ] The anterior-posterior diameter of the eye c (IJ shows a very slight degree of negative allo- :> Growth in Striped Marlin - MORROW ' 57
metry, but again this is not significant. The slightly longer than the ventral, although measurements made by Gregory and Conrad there is a tendency in these adult animals for also do not indicate significant allometry in the tail to become more nearly symmetrical the eye. with greater size. Comparison of the two It was not possible to measure the distance flukes shows that the dorsal fluke is nega between the posterior edge of the eye and the tively allometric with respect to the ventral pectoral base along the mid-line of the body fluke, with k=0.843, sk~O.071, P<0.05. with reasonable accuracy, so this measure Thus, the rate of growth of the dorsal fluke .ment was made directly between the eye and relative to the rate of growth of the ventral the anterior margin of the pectoral base. This fluke decreases as the gross size of the flukes distance is distinctly isometric. Even though increases. this is a slanted measurement, it is close With respect to the standard length, both enough to the mid-line so that, in combina the dorsal and ventral moieties of the caudal . tion with the isometry of the sword length, fin exhibit highly significant degrees of it suggests that the relative length ofthe head negative allometry in this sample . For the also remains constant. dorsal fluke, k = 0.554, for the ventral fluke, When the length-weight relationship is k = 0.611. Both these values represent de isometric, as in the present example, the same partures from isometry which are significant . condition is to be expected in depth and at P < 0.001. Thus, the rate of growth of the girth, for these two dimensions may be con tail relative to the rate of growth of the fish sidered as linear components of weight. One as a whole tends to decrease rapidly with of the more obvious differences in body form greater size in adult animals. between the striped marlin and the blue and It is interesting to compare these data on black marlins is illustrated more simply by the tail with those derived from the measure the isometry of these measurements than by ments published by Gregory and Conrad the length-weight relationship. In the striped (loc. cit.). Their group of 17 specimens from marlin, the equilibrium constants for depth Cape Brett shows negative allometry in the and girth are 0.998 and 0.929, respectively. lengths of the caudal flukes quite comparable Shapiro (1938: 7) reports k = 1.45 for depth to that reported here for fish from the same of body in the blue marlin. We have found area. no data on the black marlin, but Nichols and By contrast, their sample of nine fish from LaMonte (1941: 8) describe this species as Mayor Island , some 175 miles to the south "Heavier at larger sizes ...," which certainly east, exhibits positive allometry in both suggests positive allometry in depth and the dorsal and ventral flukes, although this girth. Thus, the greater depth of the body in allometry is of a low order of significance the blue and black marlins is reflected in the (P = 0.09 for the dorsal flukes and 0.04 for higher equilibrium constants. the ventral flukes). Nevertheless, there ap The length of the longest ray of the pec pears to be a real difference between the two toral fin shows slight negative allometry, with geographical groups as shown by a com k=0.707, P=0.065. This slight negative parison of the k values for the nine fish from allometry is not shared by either of the Mayor Island and those of the 47 fish of the samples examined by Gregory and Conrad . present sample from the vicinity of Cape The two flukes of the caudal fin were Brett (P