Fishes Killed by the 1950 Eruption of Mauna Loa I. The Origin and of the Collections

W. A. GOSLINE, V. E. BROCK, H. 1. MOORE, , and Y. YAMAGUCHI 1

THE GREAT MAUNA LOA plays the column into a water-impervious shell many parts in the Hawaiian community. We through which the rest of the lava flowed. are here concerned with its, role as a fish (Such conduits, now hollow and sometimes collecting apparatus. The present paper, which extending for distances Of more than a mile, is the first of a series that will deal with the are well-known features of the Hawaiian ter­ the fishes made available to uS by the 1950 restriallandscape.) Since the molten material eruption, is limited to an account of the gen­ flowed continuously without ever filling this eral nature of our collections. shell, it can be assumed that the lava was The Mauna Loa lava flows of June, 1950, breaking out somewhere below. Such out­ reached the sea on the Kona coast of the breaks presumably produced steam explo­ Island ofHawaii at three main points (Fig. 1). sions which could be felt even in a skiff The first two of these flows dwindled to al­ anywhere near the flow. However, no steam most nothing a short time after entering the from these assumed outbreaks ever reached water on the morning of June 2. The third the surface, nor was this to be expected unless flow has far greater significance for us. It they had been very large or very near the entered the ocean somewhat to the south of surface. the other two (at 19°16'N., 155°55'W.) on The total amount of lava entering the sea the afternoon of the same day. Surges of lava from the 1950 eruption was estimated by from this flow continued to pass into the sea Macdonald and Finch (1950: 1) at over 100 in quantity through June 4 and in lesser million cubic yards. amounts through June 7. Whenever a heavy surge of lava hit the sea, a large amount ofsteam rose from the surface (Fig. 2). Between the peaks of the surges, Jat least during the later stages of the flow, the moving column oElava entered the sea quietly, unexpectedly resembling an escalator disap­ pearing through the floor of a department 19·IS'-f-----;r---+-I-+-+-++--±:'''b store (Fig. 3). Apparently the failure to cause surface steam at such times was due to the cooling and hardening of the outer layer of FIG. 1. Land areas covered by the Mauna Loa lava Bows of 1$>19 and 1950. Heights above and below given in rhousands of feet. Diagonally hatched 1 Universiry of ; Terrirory ,of Hawaii, Divi­ areas: 1950 Bows; those that entered the sea are num­ sion of Fish and Game; U. S. Fish andWildlife Service; bered in the sequence with which they reached sea and Terrirory of Hawaii, Division of Fish and Game, level. Stippled area: 1919 Bow. Redrafted in part from respectively. Manuscript received January 17. 1953. Macdonald and Finch. 23 24 PACIFIC SCIENCE, Vol. VIII, January, 1954

water was still being formed closer in. The molten lava was still pouring into the sea continuously (Fig. 3), but in surges of greatly varying volume. The average width of the column entering the water at this time was perhaps about 30 feet. On June 7 lava was entering the sea in greatly decreased volume and more or less intermittently, ceasing completely on this day or the next. Four collections were made of the fishes brought to the surface of the sea by the 1950 FIG. 2. Third lava flow reaching sea level on]une 3. lava flows. On the morning orJune 2 Brock flew over the area where the lava was entering Concerning sea conditions around the lava the water and made awingements for collect­ flow on June 2, Finch and Macdonald (1950: ing. In the .afternoon of the same day Eugene 6) state: Burke and Homer Hayes of the Territorial By 5:00 P. M. a line of steaming water, marking Division ofFish and 'Game took a small the sub-sea coutse of the flow, extended to sea for about.half a mile from the point where the ... fl'ow number of fishes. On June 3 the U. S. Fish entered the ocean. Close to the shore and directly and Wildlife Service vessel "Henry O'Malley," over the submerged flow, the water was boiling, with Moore as scientist in charge, sent into and a semicircular area of hot turbulent water ex­ rended for a mile offshore. Many fish were killed the area a small boat from which collections' and were seen drifring or were washed up on shore were made in both the morning and afternoon. during succeeding days. The prevailing currents On the morning of June 6 Yamaguchi col- drifted the area of hot water southward. ,lected from a skiff. That afternoon Gosline, On the morning of J uf.le 3 there, was a Homer Hayes, and Ed Keen took specimens "windrow" of dead fishes, 2, to 6 feet wide from a sampan owned by Keen. On June 7 and extending as far as the eye could see, Hayes and Gosline returned to the area but about 2 miles offshore from the flow. Inside found almost nothing. ' this windrow, which marked a border be­ Circumstantial evidence' is rather strong tween murky green and deep blue oceanic that most of the fishes taken were brought water, were other smaller, linearly arranged to the surface during the early middle stages aggregations of dead fishes. At approximately ofthe third flow.'We know,that the first stages half a mile from the point ofentry ofthe lava, of all three flows killed mostly inshore fishes, the water-cooled engine of the boat from and we saw few of these. On the other hand, which these observations were made became by June 6 relatively few fishes were coming overheated. to the surface, though live specimens were By the afternoon of June 3 the windrows still occasionally seen. Furthermore, speci­ of fishes had broken up. mens in the June 6 collections often showed On June 6 the water in a roughly semi­ signs ofmore or less advanced decompo~ition. circular area several miles in radius around Some of the fishes in these collections, par­ the point of entry of the lava was discolored ticularly those taken on the first two dates, and of dirty appearance. The relatively rare are in excellent condition. 'Others are not. and scattered fish carcasses were found mostly Some of the latter were parboiled, some were toward the periphery of the disturbed area. partially decomposed, and some were both. Water a quarter of a mile from the flow was The myctophids collected onJune 6 gave the hardly warm, though a slick of upwelled hot impression that if one looked at them in- Fishes Killed by 1950 Eruption - GOSLINE et at. 25 tently their scales would fall off. Neverthe­ .' records for .such fishes as Opisthoproctus, of less, the specimens in these four collections which we took five specimens, indicate that are probably in a better sfate of preservation at least some of our material is from rather than is most deep-water fish material. deep water, presumably greater than half a Certain highly desirable data concerning mile. our collections are unobtainable. For one We also do not know how representative thing, little can definitely be said about the. our collections af(~ of the total fish fauna depth from which these fishes came. Some of living in the area. Four types of selectivity our specimens, such as the brotulids, are deep­ have probably restricted the representative­ water bottom forms. Others like the mycto­ ness of our sample. Two of these are due to phids arebathypelagic. A few probably 'our collecting methods and can be taken into normally inhabit the surface layers ofthe open account. First, we made no effort to collect ocean. A very few are obviously inshore forms the obviously inshore forms. Second, small which had drifted into the area where we were fishes were almostcompletely missed because collecting. The maximum depth at which our we took only what we could see and catch fishes were killed is likewise unknown. The with a dip net from 'a boat.'The other possible most that can be said is that the known depth selective factors are: differential decimation

FIG. 3. The third lava flow entering the watet sevetal days later. Photograph by Jack Matsumoto. 26 PACIFIC SCIENCE, Vol. VIII, January, 1954 among the species in the area and differential ' It does seem apparent that, regardless oEthe flotation among the species killed. These last amount of mixing, fishes with a high specific two factors are impossible to evaluate, and gravity would be less readily transported to the best that can be done is to point out their the surface than those with lighter bodies. possible effeds. Likewise, among fishes with the same spec­ Death ofthese fishes may have been brought ific gravity, those with a higher surface­ about by one or more of four causes: (1) the volume ratio, e.g., small fishes, would be fishes may have been killed by simple over­ more easily carried in the upwelling water heating; (2) the lava entering the water may than those with a lower surface-volume ratio. have introduced some directly or indirectly It is possible, however, that not all the fishes lethal chemical; (3) fishes with an air bladder· we collected were originally brought to the may have been carried upward so rapidly by surface by upwelled water, but rather that, the upwelling water as to have caused over­ some of them were forced up after death by expansion of this organ; and (4) the under­ gases of decomposition. water explosions, caused by the breaking out This possibility leads into the question of of the molten lava from ;the conduits, may why fishes were at the surface when we got have caused some mortality. We do not have there. Evidence from some of our specimens evidence that would make profitable a dis­ indicates that their air bladders became over­ cussion of any of these possible causes of expanded and remained so after death, serving death. With any of them, however, it would as floats. However, others show no expansion seem likely that large fishes would be better of an air bladder, and a large number of our able than smaller ones to move out of the specimens presumably do not even possess way in time to avoid harm. The differentiai this organ. The presence of such fishes at the in decimation between large and small fishes surface can best be explain~d by hypothesiz­ may have been increased by the possibility ing the formation ofgases in parts ofthe body that the water moving in to replace that. which other than the air bladder. For example, the had upwelled carried with it small, weak two brotulids we took on June 6 had the swimmers from the surrounding region into belly (but not the air bladder) greatly dis­ the outbreak area. tended and empty. Most of our specimens, Concerning the possibility of differential however, showed no abdominal distension. flotation, our only evidence is from the spec­ Whether decomposition gases and air bladder imens we collected. With regard to these, two expansion can explain the presence of all our questions arise. What brought them to the . fishes at the surface seems open to question. surface, and, once there, why did they not Whatever the full explanation is, it must take sink back to the bottom? As' to the first, one into account the fact that, with the exception might suspect that the water heated by the of two jellyfishes, we found no organisms lava would make its way through the water other than fishes at the surface. column above it to the surface, where it would Our four collections together probably to­ spread out as a thin layer. Under such a tal 300 to 500 specimens distributed among hypothesis only the fishes from the area more than 20 families. Perhaps a third of the around.the outbreaks would be brought to individuals are myctophids. Except'for the the top. Actually our collections contain epi­ Myctophidae, and to a lesser extent the Ster­ pelagic arid a large numb.er of bathypelagic noptychidae, none of the families is repre­ fishes, as well as bottom forms. The presence sented by more than a few specimens. Among of these pelagic species can best be explained groups unrepresented in our collections are by hypothesizing considerable mixing be­ sharks, flatfishes, and angler fishes. tween the rising water and that around it. In number of species our material would Fishes Killed by 1950 Eruption - GOSLINE et al. 27 seem to be much richer than the number of It is planned to publish reports on the va­ individuals might indicate. For example, each rious groups in our collections in this journal of the five brotulid specimens represents a as they are completed. The section on bro­ different species. Such a representation indi­ tulids has been finished and appears elsewhere cates the variety of fish life that must exist in this issue. Specimens ofcertain groups have in the deeper waters around Hawaii. Another been sent out to be worked up by others: piece of evidence bears on this same point. the zeoids by Dr. George Myers, the myeto­ In 1922 Jordan reported on seven species phids and gonostomatids by Dr. R. L. Bolin, collected from the sea around the point of both of Stanford University, and the sterno­ entry of the 1919 lava flow (Fig. 1), six of ptychids by Miss Janet Haig, of the Allan which he described as new. Of these seven Hancock Foundation. species, at least three and probably six were For constructive criticism and help in pre­ not taken by us. paring the present paper we wish to thank There appear to be only two extensive re­ Dr. R. L. Bolin, Dr. C. K. Wentworth, Mr. ports on the deep-water fishes of the Central T. Cromwell, and various members of the Pacific (Gilbert and Cramer, 1896; Gilbert, University of Hawaii faculty. 1905). Both of these are based on dredge hauls made by the "Albatross" in Hawaiian REFERENCES waters. In the later paper, which summarizes the results, Gilbert recognizes 111 species FINCH, R. H., and G. A. MACDONALD. 1950. taken below the 100-fathom line. Since 1905 The June 1950 eruption of Mauna Loa. occasional deep-water forms, mostly taken Part 1. Narrative of the eruption. The Vol­ by fishermen, have been added to the Ha­ cano Letter () 508: 1-11. waiian fauna from time· to time. The only GILBERT, C. H: 1905. The aquatic resources previous paper based on Hawaiian fishes of the . Part II. Section killed by a lava flow is that by Jordan (1922) II. The deep-sea fishes. U. S. Fish Comm., mentioned above. Ett!' for 1903, 23(2): i-xi, 577-713, pIs. After the "Albatross" material, the 1950 66-101. lava-flow collections constitute the most im­ --- and F. CRAMER. 1896. Report on the portant deep-water fish material yet taken in fishes dredged in deep water near the Ha­ the Central Pacific. Their value is enhanced waiian Islands, with descriptions and fig­ by the fact that, though there is some overlap, ures oftwenty-three new species. U. S. Natl. the 1950 collections by no means duplicate Mus., Proc. 19: 403--435, pIs. 36--48. those taken by the "Albatross." For example, JORDAN, D. S. 1922. Description of deep-sea we took five species of brotulids whereas fishes from the coast of Hawaii, killed by Gilbert did not record any; conversely, in a lava flow from Mauna Loa. U. S. Natl. another bottom-fish group-the flatfishes­ Mus., Proc. 59: 643-656. Gilbert reported 13 species and we did not MACDONALD, G. A., and R. H. FINCH .. 1950. take any. Such examples, though extreme, The June 1950 eruption of Mauna Loa. again indicate the tremendous size of the Part II. Special features. The Volcano Letter fauna from which our samples wete drawn. (Honolulu) 509: 1-6.