Fishery Oceanography from Space

1969 (6th) Vol. 2 - Space, Technology, and The Space Congress® Proceedings Society Apr 1st, 8:00 AM Fishery Oceanography From Space Kirby L. Drennan Dept. of the Interior Follow this and additional works at: https://commons.erau.edu/space-congress-proceedings Scholarly Commons Citation Drennan, Kirby L., "Fishery Oceanography From Space" (1969). The Space Congress® Proceedings. 2. https://commons.erau.edu/space-congress-proceedings/proceedings-1969-6th-v2/session-9/2 This Event is brought to you for free and open access by the Conferences at Scholarly Commons. It has been accepted for inclusion in The Space Congress® Proceedings by an authorized administrator of Scholarly Commons. For more information, please contact [email protected]. FISHERY OCEANOGRAPHY FROM SPACE Our initial effort at Pascagoula was to Kirby L. Drennan determine the potential application of standard aerial photographic techniques as a means of Bureau of Commercial Fisheries obtaining quantitative and qualitative data on Exploratory Fishing and Gear Research Base pelagic fish stocks. The field activities Pascagoula, Mississippi associated with this program were concluded in May of 1968 after more than 1,000 schools had been photographed using black and white, color, The exploration and utilization of world and color infrared films and filter combinations. oceanic fishery resources have been limited in Sixty-five of these schools were sampled in an the past for lack of a technology which could effort to determine size and species composition. provide the observations required for rapid Simultaneous sonar soundings were also obtained assessment, real time intelligence, or the en of a number of schools in an effort to determine vironmental monitoring necessary to determine sub-surface configuration and school density. the space time ecosystem relationships on which Preliminary results show that both the position a predictive system could be based within usable and surface configuration of fish schools at or time factors. near the surface may be precisely determined from high altitude photography. An effort is The space agency has undertaken an exten now being made to correlate the photographic sive study to determine if it would be eco imagery with the "ground truth" data and sonar nomically feasible to develop a satellite soundings obtained during the field operations. system to survey the resources of the earth. Upon completion, forty transparencies of fish This satellite would be equipped with various schools of different species will be subjected types of sensors which operate on the principle to densitometric analyses. Transmissivity of that each object on earth reflects, absorbs, the images will be measured in the red, green, or re-emits energy in a manner characteristic and blue spectral regions, and with white light. of the object's physical and molecular structure These data will then be subjected to a statisti giving each its own spectral signature. The cal analysis to determine correlations between Bureau of Commercial Fisheries Exploratory spectral transmissivity and species, surface Fishing and Gear Research Base, Pascagoula, area of schools and quantity of fish in school, Mississippi, in cooperation with the National and transmissivity of image and school size. It Aeronautics Space Administration's Spacecraft is believed that this study will serve to de Oceanography Project, is engaged in a program termine the potential application of the photo which seeks to apply existing remote sensing graphic techniques employed as a means of technology to the problems of fishery resource identifying and quantifying pelagic fish stocks. assessment, i.e., the location, identification, and quantification of surface and near-surface The distinctive color of certain species fish stocks. Several approaches are being suggests that measurements of the spectral taken in this effort. These include studies energy distribution may reveal characteristic of the reflectance spectra of fish schools and spectral signatures which may be used to locate associated surface fish oil films; the intensity and identify fish schools in their natural en and spectral emittance of bioluminescence vironment under certain conditions. During associated with most schools, which may permit September 1968 the Pascagoula Base and TRW night-time detection of fish schools through Systems obtained spectral reflectance measure the use of low-level light sensors; and the ments of fifteen schooling species in the north possible application of a pulsed laser system ern Gulf of Mexico. Measurements were made on which may provide a means for locating fish single fish, fish in small groups and fish in schools at sub-surface depths. Results of schools inside impoundments using a recently studies conducted in these areas by the Bureau developed TRW Water-color Spectrometer. of Commercial Fisheries, Pascagoula Base, are the subject of this paper and are discussed This Spectrometer (figure l) was designed in the following sections. for field use, is aircraft rated, and possesses the characteristics described in table 1. It Spectro-Photographic Studies receives incoming light focused by the objective lens on a narrow slit located at the focal plane Many species of pelagic fish can be dis of a parabolic mirror. Light which passes tinguished on the basis of color by a qualified through the slit is reflected by the spherical observer. These color differences are used mirror onto a reflection diffraction grating, by spotter pilots of the commercial fishing The diffracted light reflected from the grating industry to locate and identify commercial fish is reflected by the spherical mirror and focused stocks. The experienced spotter also uses a on the base of the rotating disc located in the number of other features in addition to color, front of the sensitive end of a multiplier photo to locate and identify fish. These are the tube. A slit in the rotating disc allows only presence of fish-oil films, diving birds, a small portion of the spectrum to reach the face ripples, and, in some cases, a churning of the of the phototube and as the disc rotates the slit waters. It is assumed, on the basis of these successively permits light from, all portions of and other considerations, that present airborne the spectrum to register on the face of the and spaceborne sensors, which outperform the phototube. In this study, output from the tube human eye in many important respects, may be was recorded on a paper strip chart recorder. used to locate and identify surface and near- surface fish stocks. 9-1 The observational program was conducted in however, fishing is also done on cloudy nights. the area extending from Cape San Bias westward to Mexico Beach, Florida. All data were ac A search of the literature dealing with the quired aboard a Bureau vessel and from "Stage spectral characteristics and geographical dis II", a Texas type tower which was made available tribution of luminescing animals has revealed to the Bureau of Commercial Fisheries by the the following: U. S. Navy Mine Defense Laboratory, Panama City, Florida. Thirty-three of approximately 120 1. Bioluminescence is usually evident in spectra obtained during this period were ana the upper layers of the ocean usually within lyzed by TRW. Examination of these data indi the Euphotic Zone or above the Thermocline. cate that, in general, the reflectances are separable on a species basis and are different 2. Luminescent flashes may have an from sea-water reflectance. The results of intensity as high as 10~ 2 microwatts per square this initial research effort prove the strong centimeter and are well above the visual thresh potential for application of remote spectral old of the human eye. sensing for fishery resource assessment. It also appears that existing sensor technology 3. Four species of dinoflagellates were is adequate in resolution and sensitivity to shown to have similar emission spectra with a discern differentials and color spectra in spectral peak between 470 and 480 ran. The a variety of pelagic schooling species. In wavelength of maximum transmissivity in clear this study, measurements were made on a oceanic water. relatively large variety of species in an effort to gain an impression of the range of signatures 4. Two types of bioluminescence are recog which might be available and the feasibility nized, the steady glow and the flash. Both of detecting and classifying species by remote responses can be induced in Noctiluca miliaris sensing. However, these data were acquired by prolonged or sudden mechanical stimulation. under laboratory-like conditions, and it must now be determined whether these techniques 5. Dinoflagellates luminesce upon agi will achieve similar results when applied to tation by schooling fish which is observable schools of fish in the sea. The second phase from the air at night. Night aerial spotting of this research will be concerned with the operations have been conducted off southern reliability and application of these techniques California to locate sardine schools. in a field program. During the coming months, observations will be made of the reflectance 6. It appears that fish schools may be spectra of a number of commercially important seen to a depth of 10 fathoms under certain species in their natural environment. These conditions. observations will be made on captive schools under a wide range of known (monitored) en During the past four months a series of vironmental conditions of sea-state, lighting tests have been conducted by the Pascagoula conditions, and water turbidity. It is antici Base from Coast Guard helicopters, fixed-wing pated that the results of these tests will aircraft, a stationary oceanographic platform, determine the feasibility of an operational and surface vessels using a Plumbicon Television system which will provide a means for location Image Intensifier system (figure 3). The image and identification of fish school from obser intensifiers, loaned to us by the Night Vision vations of the spectral energy distribution. Laboratories, Fort Belvoir, Virginia^ amplify the ambient light, or in this case the bio Night-time Detection of Pelagic Fishes Through luminescence., 40,000 times.

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