History of Ichthyology

INTRODUCTION

The Holy Bible is the first book that declared Adam as the first person to name species. However since this web site is dealing with recorded scientific information we must forego the theological path and instead focus on Man's ichthyologic method record. The sciences essentially began in Europe and later works in the New World were to advance European sciences. For practical purposes, science is still relatively young in the Americas. Many overlooked works can be found in manuscripts by Christopher Columbus who wrote about the fauna he saw in the New World or the Egyptians who catalogued their fishes on pyramid walls. Even Leif Ericsson's explorations which predated Columbus had mention of fishes that later scientist's would "discover." But even with this knowledge of history, we mustn't overlook the aborigines who themselves named species. Some of which bear the native name in the species binomen.

The beginning of taxonomy can be probably traced to John Ray (1628-1705). Ray introduced the complex grouping system and greatly improved the language description. Ray used the genus and species method of naming organisms. Prior to that the Greeks and Romans, notably Aristotle (384-322 B.C.) is credited with starting taxonomy having an accurate knowledge of fish anatomy and able to correctly distinguish aquatic mammals or cetaceans. But it was the work of the next author that drew the most praise and credit.

Karl Linnaeus (1707-1778) brought sharp focus to the method used today. Linnaeus (see picture at left) is considered by all as the "father" of taxonomy. It was his work that was massive in its undertaking, surpassing all before him including Ray. Linnaeus created a system of keys for naming species that were simple to use. This enabled many to use the method to identify organism's themselves. Linnaeus first classification of nature (minerals, plants and animals) appeared in 1735 and was immediately accepted by his peers. He grew in stature and reputation throughout the world. Later, he would establish a school (University of Upsala) in Sweden, which became the center of taxonomony which students from all over the world came. He called his work Systema Naturae. This work was in its 13th edition when Linnaeus died in 1778, this work however was carried over through more editions by his students for the next 50 years. Modifications took place over time following the method first established by Ray. By the 10th edition the list of names and species became shorter and shorter to its abbreviated form. Linnaeus suggested that it was sufficient it if merely identified the species among those of the genus. This simple answer established the binominal system of nomenclature.

Linnaeus further gave names to groups larger than the genus, establishing the class (similar to what Aristotle had established). The first was called CLASSES and each was divided into ORDERS, which then were broken down further to genera and species. By 1800 other workers introduced FAMILY as a category between ORDER and the genus. Finally, the classes were grouped into higher categories called PHYLA.

The 10th edition of Systema Naturae is the first publication to adhere strictly to binominal nomenclature, one of the International Rules states that no name published prior to this is valid. Hence, the 4,236 descriptions in this book include the earliest species are considered and accepted as official. The International Rules of Zoological Nomenclature require that whenever a new species is discovered and described the name of the designated species must be called a Holotype on which the species is based. Other species used in describing the new species become paratypes, and the data collected from them is included in the description. It is customary for ichthyologists to give the designated type to (country of origin) museums for permanent preservation. This then can be reviewed and used for research by professional ichthyologists and students who are qualified.

But problems would begin to surface that would lead to more changes and a new burst of interest in this work. The 19th century saw rise of a period called "romanticism" and a philosopher by the name of Johann Wolfgang von Goethe paved the way in city-state of Weimar in Germany. He was a poet and a biologist among other things. His belief in harmony and the inherent goodness of nature started a new trend which was called "nature-philosophy" as a method understanding life. This however did not last long as the generation began to mature more. Georges Cuvier was a biologist in France (survived not only the French Revolution but Napoleon too) and extended single-handedly a new method of classification called comparative anatomy. By reconstructing bones of extinct animals (fossils) he began the laborious task of naming them. This resurgence however did not last long even though Cuvier work uncovered many things that were once considered distinct. The concept of evolution was not accepted nor popular at the time and Cuvier et al., were vehemently opposed to it. The thought of those days was that all creatures were created just as they were. The original method of Linnaeus had not been realized yet and taxonomy declined after 1832.

Charles Darwin entered the arena in 1858 and by that time taxonomy was facing its worst crises, lack of interest by scientists. When Darwin presented his ideas and arguments about evolution eyes perked up and now a newer method was being devised. In Cuvier's time evolution would have been unthinkable and unscientific. Even by today's standards Darwinism as it was known then postulated that man descended from a common ancestor, the ape. This was met with much controversy even court action to prevent schools to teach was is now called "Evolution." Darwin was able to postulate the "why" of a species where before it could never be asked. This allowed a species to be better defined as an evolutionary unit, as well as a taxonomic category.

Ichthyology

Ichthyology which is the focus of this OPEFE website was confronted with many inadequate descriptions and figures of fishes printed during the over 200 years since records were first kept. The first original observations may be attributed to Pierre Belon (1517-1575) in De aquatilibus libri duo; Hyppolyto Salviana (1514-1572) in Aquatilium animalium histoae...; and Gulielmus Rondelet (1507-1566) in libri de piscibus marinis, whose works are almost entirely limited to Mediterrean and European fishes.The next century, Guilielmus Piso (1611-1678) and George Marcgrav (1610-1644) accompanied Prince Moritz of Nassau (1604-1679) to Brazil in 1637-1644 approximately 100 species of fish. It was about this time John Ray (see above) and Francis Willoughby (1635-1672) and ichthyology flourished.

A Swede by the name of Peter Artedi (1705-1735) surfaced from the University of Uppsala, Sweden. His earliest investigation were more important than others before him. There are those who consider him the father of ichthyology. In 1728 Karl (Latinized as Carolus) Linnaeus visited this university. Linneaus inquired as to who was engaged in the study of natural history and he was then referred to Artedi. That is how they met and became friends. Each helping the other not only in personal money needs but even making an agreement that the survivor would publish the works of the one deceased. Artedi drowned in 1735 in Holland. Linnaeus true to his word published Artedi Ichthyologia in 1738. Artedi method was that he believed that a genus represented a group of species which agreed with each other in general but which differed in minor characters. Having established the generic concept, Artedi proceeded to group the genera into "maniples." This is the same family concept used today. The maniples were arranged into natural orders, and these into a class, representing the whole group of fishes. In all Artedi recognized 47 genera and 230 species. The only weakness in this rating was below the genus. He retained the polynomial scheme of nomenclature. There is no doubt Artedi greatly influenced Linnaeus.

Many more ichthyologic works would follow Artedi and Linnaeus. Some of those names include, Otto Fabricus (1744-1822), Petrus Forskål (1736-1763), Petrus Pallas (1741-1811), Antione Risso (1777-1845), Thomas Pennant (1726-1798), Wlhelm G. Tilesius (1769-1857), Georg Wilhelm Steller (1709-1746). Constantine Samuel Rafinesque (1783-1840), had the dubious distinction of having described and published non-existent animals. This as a result of a friend suggesting the famed bird painter Audobon meet Rafinesque since both shared a passion for natural history. This was during the summer and Rafinesque having impressed Audobon with his knowledge of natural history was invited to spend the night in Audobon's cabin. During the night, Audobon awoke to a commotion in the naturalist room. To his astonishment he saw his guest, running naked, holding the handle of Audobon's favorite Cremona (a violin), the body of which was battered to pieces in attempting to kill bats for examination. Audobon as earlier stated was a noted artist and famous for painting birds. He used this skill to create non-existent animals by placing the head of one and then painting onto the body of another. Perhaps revenge in his heart Audobon gave these paintings to Rafinesque and the naturalist immediately set out in describing these new species. Ten of these were actually published in Ichthyologia Ohiensis.

Marc Elieser Bloch (1723-1799), Bernhard G.E. Lacepède (1756-1825), Georges L. C. F.D. Cuvier (1769-1832) and Achille Valenciennes (1794-1865). The first ichthyologist to publish an actual description can be traced to an American named LeSueur (1821). The species described was Mollinesia latipinna, commonly called the sail-fin Mollie. In those days there was a lot of carelessness in describing and naming new species. Many of the plates used as illustrations contained many errors in spelling, etc. Because the egregious mistake in spelling of Mollinesia was in dispute (the plate illustration had the name misspelled as Molinesia) it took three ichthyologist in the future to investigate and correct the nomenclature error.

The last attempt to write a series of volumes on the fishes of the world was by Albert C.L.G. Günther (1830-1914). This work was entitled Catalogue of the Fishes of the British Museum. It was published in eight volumes from 1859-1870. To many species were being discovered and the task became more complicated. More work than one person could accomplish. The local fauna was by and large greater than what was once thought and could not be worked into the treatise on fishes of the world. The next serious attempt was made by Johann Baptis von Spix (1781-1826) and Louis Aggassiz (1807-1873). This work pertained to Brazilian local fauna and related fishes. Johann Müller (1801-1858) and Friedrich G. J. Henle (1807-1885) produced the first authoritative work on sharks (Systematische Beschriebungen der Plagiostomen) in 1841. Peter Bleeker (1819-1878) published 500 separate contributions, chiefly on the fishes of the tropical Indo-Pacific. His book which was not only fully illustrated, it was one of the best 9 volumes from previous works of other authors. The book name is Atlas Ichthyologique des Indes Orientales Néerlandaises, 1862-1877. The literature from that work is the most accurate and comparable to many literature found today.

Cuba also had a notable ichthyologist by the name of Felipe Poey y Aloy (1799-1891). He labored for over a 50 years on the local fish and fauna. Japan also produced other ichthyologic works by Coenraad Jacob Temminck (1770-1858) and Herman Schlegel (1804-1844). Their work catalogued the fauna and fishes of the Japanese island. There were other ichthyologists from other lands (way to many to list here), but some other notable ones include; Franz Steindachner (1834-1919), George Boulenger (1858-1937), Robert Collett (1842-1913), Carlos Berg (1843-1902), Francis Day (1829-1889), and Leon Louis Vaillant (1834-1915).

American Ichthyology is dated from the feeble beginnings of Rafinesque and from Samuel Latham Mitchill (1764-1831). His work pertained to the treatise on the fishes of New York. Shortly after that Charles Alexander LeSueur (1778-1846) reported on the Great Lakes and Ohio basin. He was an artist and naturalist. Other American ichthyologist surfaced during that period; Jared Potter Kirtland (1793-1877) on Ohio fishes; James Ellsworth DeKay (1792-1851) on the New York fauna; John Richardson (1787-1865), published Fauna boreali-Americana in 1836. Massachusetts also produced an ichthyologist named David Humphreys Storer (1804-1891) who focused his work on the fishes from that state. South Carolina fishes were examined and written about by John Edwards Holbrook (1796-1871).

In 1846, The Smithsonian Institution was created in the city of Washington, D. C. This institution was under the direction of the United States government. This gave a permanent residence to the United States National Museum where specimens could stored and later reviewed by people interested in North American fauna and the fauna found in the world. The U.S. National Museum, Division of Fishes is so large that very little space is available for its multitude of specimen jars exceeding 300,000. This collection belongs to the people of the United States and is available only those students qualified in ichthyologic studies. This collection is very similar to a book library where the student can research past observations and record new ones. The institution is assisted by the U.S. Fish and Wildlife Commission who has a history of systematic ichthyologic leadership in investigations over a century old. Noteworthy contributions can be traced to G. Brown Goode (1851-1896) and his Oceanic Ichthyology; David Starr Jordan (1851-1931) in collaboration with Charles Henry Gilbert (1859-1928) and Barton Warren Evermann (1853-1932) were responsible for publishing over 100 citations on American fishes. Henry W. Fowler (1878-?), Academy of National Sciences in Philadelphia, did many citations on Philippine collections using his on ship called Albatross. Furthermore, Fowler in 1945 and Bailey & Miller in 1950 examined the work by LeSeur amended the name to Mollienesia which closely followed the name of the man it was supposed to honor, LeSueur. This was the first time an examination of ichthyologic review was ever done in order to correct an egregious error in a citation. A volume of fishes in Peru was provided by Samuel Frederick Hildebrand (1883-1949) and that on freshwater fishes of Thailand (then Siam) by Hugh McCormick Smith (1865-1941).

Louis Agassiz (1807-1873) in 1850 wrote a monograph on the fishes of Lake Superior and trained one of his students, Charles Frederic Girard (1822-1895), in ichthyology. Many fish collections and preservations were completed during the United States Pacific Railway surveys which were brought back to Washington. Here Spencer Fullerton Baird (1823-1887) published the survey fauna (mostly from the Western United States) with the assistance of Girard. Baird was one of the secretaries to the Smithsonian Institution during this time. Also engaged in these earlier explorations were James Wood Milner (1841-1879), Marshall McDonald (1835-1895), William O. Ayers (1817-1891), William Neale Lockington (184?-1902), and George Suckley (1830-1869) among others.

Certain American educational institutions (latter half of nineteenth century and early twentieth century) later arose into centers of leadership in the study of fishes and exploration. Harvard University had Samuel Garman (1843-1927). Garmon was a student of Agassiz and he made valuable contributions on the sharks and the deep-sea fishes collected by Albatross. Indiana University became another important research center for fishes under the leadership of David Starr Jordan during the 1880's. He would be then followed by the man whom many would call "the father of characid studies," Carl Eigenmann.

Carl H. Eigenmann (1863-1927) took over and became famous for his valuable contributions on South American fishes. Jordan had trained Eigenmann and inspired his very active ichthyologic career. Eigenmann collaborated in many of Jordan's works and Jordan would later appoint Eigenmann as professor of zoology at Indiana University. Upon Eigenmann's death his successor (Fernandus Payne) praised Eigenmann's researches by stating in his opinion "place him (Eigenmann) in the first rank of ichthyologists of all time." Jordan praised Eigenmann by saying "one of the most eminent workers in the field of systematic zoology and one of the ablest of natural history teachers, withal the most tireless of explorers." Jordan in the meantime left Indiana and took over as first president of Stanford University, California. His leadership in establishing a fish center there is still strong today. When he left Indiana he took with him Charles Henry Gilbert (1859-1928). At Stanford he gathered two important men, John Otterbein Snyder (1867-1943) and Edwin Chapin Starks (1867-1932). For half a century Standford University was the main center for training students in ichthyology. Charles Henry Gilbert was known for his methodical handling of American fishes. His work was primarily on salmon and to apply statistical methods to fishery research. This earned him the title of "the father of modern fisheries biological research in America."

Seth John Meeks (1859-1914) was another of Jordan's students and like Eigenmann revised many early group and regional papers. He largely focused his attention on freshwater fishes of Middle America. Many more followed Jordan's lead and most were his students. George Brown Goode (1851-1896) played an important role in pure and applied ichthyology in the United States. His ichthyology overlapped Jordan, but the two did not publish together. However, they did cooperate effectively. Much of his work was focused on fisheries biology, particularly that of certain commercially important fishes. His research of deep-sea fishes was firmly established since Jordan had no interest in them. Tarleton H. Bean (1846-1916) was an associate of Goode and helped lay out the rational inclusion of deep-sea fishes in the Fishes of North and Middle America. Later Bean's brother Barton A. Bean (1860-1947) followed him as Curator of Fishes in the National Museum. However his reign seemed to be (quoting from Carl L. Hubbs) "less productive and less illustratrious scientific life (during slightly more than the last decade of the nineteenth century and the first two decades of the twentieth)."

Louis Agassiz while in San Francisco picked up another fellow by the name of Samuel Garman (1843-1927) from what was then called "the Wild West." Agassiz trained Garman in ichthyology (both Garman and Jordan were fellow students under Agassiz at Penikese). In addition to publishing a considerable number of minor papers, Garman monographed the "Discoboli" (Cyclopteidae and Liparididae) in 1892, and the Cyprinodontes in 1895. Garmon's work methodical in his attention to the anatomical detail. However, he was never admired nor a member of the Jordan clique. Garmon was indeed a recluse, locking himself into his ill-lit quarters at MCZ. The period 1875-1900 knowledge of fish fauna of the Pacific Coast of the United States flourished. Several incidental studies were conducted by Louis and Alexander Agassiz, Gill, William O. Ayres, James Grahm Cooper (1830-1902), William Gibbons (1812-1897), and a few other lessor known figures. Much of the work reached a standstill during the Pacific Railroad Survey of the 1850's. That is until Jordan and Gilbert carried out their survey in 1880. The collected from British Columbia to San Diego, chiefly fish markets, which then, especially in California, contained a wide variety of inshore fishes.

This were quickly returned to their hotel room where they prepared the fishes for shipment in preservative. Many quick descriptions were done this way with prompt publication following their discovery. These were published in short papers in the Proceedings of the United States National Museum for 1880 and 1881. Never mind, that expediency for correct descriptions was the norm and this would later create problems for ichthyologists to follow. In one situation on a trip to Matzatlán and on two trips to Panamá, in 1881 and 1882, Gilbert made large fish collections that were destroyed by fire. This before a monograph on The Fishes of the Pacific Coast of Tropical America could be written!

by Frank Magallanes, OPEFE

Artikel , Perikanan

Tingkah Laku Ikan terhadap Rumpon

Rumpon (fish agregation device) dalam bahasa kelautan adalah karang buatan yang dibuat oleh manusia dengan tujuan sebagai tempat tinggal ikan. Rumpon merupakan rumah buatan bagi ikan di dasar laut yang dibuat secara sengaja dengan menaruh berbagai jenis barang di dasar laut secara kontinyu (Soemarto 1962). Biasanya, bila di suatu perairan terdapat rumpon, maka plankton akan berkumpul. Seperti diketahui plankton sebagai bahan makanan bagi ikan besar. Beberapa jenis ikan tuna dan cakalang menjadikan rumpon sebagai tempat bermain. Hal ini memudahkan bagi nelayan untuk menangkap ikan.

Definisi rumpon menurut SK Mentan  No. 51/Kpts/IK.250/1/97  adalah  alat  bantu penangkapan ikan yang dipasang dan ditempatkan pada perairan laut. Selanjutnya dalam SK Mentan No. 51/Kpts/IK.250/1/97 tentang Pemasangan  dan  Pemanfaatan  rumpon menjelaskan bahwa terdapat 3 jenis rumpon, yaitu:

1. Rumpon perairan dasar; adalah alat bantu penangkapan ikan yang dipasang dan ditempatkan pada dasar perairan laut. 
2. Rumpon perairan dangkal; adalah alat bantu penangkapan ikan yang dipasang dan ditempatkan padaperairan laut dengan kedalaman sampai dengan 200 meter. 
3. Rumpon perairan dalam; adalah alat bantu  penangkapan  ikan yang  dipasang dan  ditempatkan   pada perairan  laut   dengan  kedalaman  di atas 200 meter.

Konstruksi dan teknis pemasangan rumpon
Secara garis besar rumpon menurut Preston (1982) dalam Anonim₂ adalah tersusun dari tiga bagian utama yang terdiri dan attraktor, mooring line dan pemberat. Konstruksi rumpon, terdiri dan komponen-komponen yang sama bila dilihat berdasarkan fungsinya seperti pelampung, alat pengumpul ikan, tali-temali dan pemberat. tetapi untuk rumpon-rumpon yang dipergunakan oleh nelayan diberbagai lokasi di Indonesia mempunyai perbedaan bila dilihat dan material masing-masing komponen konstruksi rumpon tersebut.

Tim Pengkajian Rumpon IPB (1987) mengemukakan bahwa persyaratan umu komponen komponen dan konstruksi rumpon adalah sebagai berikut:

1)   Pelampung,

§  Mempunyai kemampuan mengapung yang cukup baik (bagian yang mengapung di atas air 1/3 bagian).

§ Konstruksi cukup kuat tahan terhadap gelombang dan air.

§ Mudah dikenali dari jarak jauh.

§ Bahan pembuatnya mudah didapat;

2)   Atraktor atau pemikat,

§  Mempunyai daya pikat yang baik terhadap ikan.

§  Tahan lama.

§  Mempunyai bentuk seperti posisi potongan vertikal dengan arah ke bawah.

§  Melindungi ikan-ikan kecil.

§  Terbuat dan bahan yang kuat, tahan lama dan murah;

3)   Tali-temali,

§  Terbuat dan bahan yang kuat dan tidak mudah busuk.

§  Harganya relatif murah  mempunyai daya apung yang cukup untuk mencegah  gesekan terhadap benda-benda lainnya dan terhadap arus

§  Tidak bersimpul (less knot);

4)   Pemberat,

§  Bahannya murah, kuat dan mudah diperoleh.

§  Massa jenisnya besar, permukaannva tidak licin dan dapat mencengkeram.

Daya tahan rumpon yang dipasang di laut sangat bervariasi tergantung jenis material dari masing-masing komponen serta kondisi dan kedalaman perairan dimana rumpon tersebut dipasang. Tim Pengkajian Rumpon IPB (1987) mengemukakan bahwa berdasarkan hasil evaluasi rumpon yang dipasang PT. Usaha Mina di Perairan Utara Irian Jaya dan  di perairan Maluku utara dapat disimpulkan bahwa rumpon yang dipasang pada kedaan 600-1000 m dapat bertahan antara 10-17 bulan

Menurut Atapattu (1991). penggunaan rumpon sebagai alat bantu penangkapan mempunyai tujuan utama untuk meningkatkan laju tangkap dengan pengurangan biaya produksi, mengurangi waktu untuk mencari gerombolan ikan sehingga mengurangi biaya operasi kapal, meningkatkan efisiensi penangkapan serta memudahkan operasi penangkapan ikan yang berkumpul di sekitar rumpon.

Rumpon sebagai alat bantu penangkapan dipasang di tengah laut. Oleh sebab itu agar rumpon dapat berfungsi dengan dengan baik sesuai dengan tujuannya. maka dalam pemasangannya diperlukan adanya informasi tentang kedalaman, kecerahan air. arus. suhu, salinitas dan keadaan topografi dan dasar perairan dimana rumpon akan dipasang. Informasi dasar tersebut sangat diperlukan untuk diketahui agar dalam pemasangan rumpon benar-benar tepat pada perairan yang diharapkan dan menghindari rumpon putus. Pemasangan rumpon harus pula memperhatikan aspek biologis dan ikan yang menjadi sasaran penangkapan. Hal ini bertujuan agar rumpon yang dipasang benar-benar pada perairan yang subur dan banyak ikannya.

Tingkah laku ikan di sekitar rumpon

Menurut Asikin (1985) mengemukakan bahwa keberadaan ikan di sekitar rumpon disebabakan oleh bebrapa hal, antara lain:

1. Rumpon sebagai tempat bersembunyi di bawah bayang-bayang daun rumpon bagi beberapa jenis ikan tertentu;
2.  Rumpon sebagai tempat berpijah bagi beberapa jenis ikan tertentu; 
3. Rumpon itu sebagai tempat berlindung bagi beberapa jenis ikan yang mempunyai sifat fototaksis negatif.

Samples dan Sproul (1985) mengemukakan teori tertariknya ikan yang berada di sekitar rumpon disebabkan karena:

1. Rumpon sebagai tempat berteduh (shading place) bagi beberapa jenis ikan tertentu; 
2. Rumpon sebagai tempat mencari makan (feeding ground) bagi ikan-ikan tertentu;
3. Rumpon sebagai substrat untuk meletakkan telurnya bagi ikan-ikan tertentu; 
4. Rumpon sebagai tempat berlindung (shelter) dan predator bagi ikan-ikan tertentu;
5.  Rumpon sebagai tempat sebagai  titik acuan navigasi  (meeting point)  bagi     ikan-ikan tertentu yang beruaya. 

Selain kelima teori di atas Gooding dan Magnuson (1967) dalam Anonim₂ megemukakan bahwa rumpon merupakan tempat stasiun pembersih (cleaning place) bagi ikan ikan tertentu. Dikemukakan bahwa dolphin dewasa umumnya akan mendekati bagian bawah floating objects dan menggesekkan badannya.  Breder (1949) dalam Anonim₂  juga mendukung hal ini dimana kadang-kadang dolphin mendekati ikan lain untuk membersihkan badannya.  Tingkah laku ini sesuai dengan tingkah laku dan famili coryphaenids yang memindahkan parasit atau menghilangkan iritasi kulit dengan cara menggesekkannya.  Freon dan Dagom (2000) dalam Anonim₂  menambahkan teori tentang rumpon sebagai tempat berasosiasi (association place) bagi jenis ikan-ikan tertentu.

Rumpon yang dipasang. pada suatu perairan akan dimanfaatkan oleh kelompok ikan tertentu sebagai tempat berlindung dan serangan predator. Kelompok jenis ini akan berenang-renang dengan mengusahakan agar posisi tubuh selalu membelakangi bangunan rumpon. Selain sebagai tempat berlindung, rumpon diibaratkan sebagai pohon yang tumbuh di padang pasir yang merupakan wadah pemikat kelompok ikan (Subani 1972).

Ikan berkumpul di sekitar rumpon untuk mencari makan. Menurut Soemarto (1962) dalam area rumpon terdapat plankton yang merupakan makanan ikan yang lebih banyak dibandingkan di luar rumpon.  Diterangkan juga oleh Soemarto (1962) bahwa perairan yang banyak planktonnya akan menarik ikan untuk mendekat dan memakannya.

Menurut Subani (1972) mengemukakan bahwa ikan-ikan yang berkumpul disekitar rumpon menggunakan rumpon sebagai tempat berlindung juga untuk mencari makan dalam arti luas tetapi tidak memakan daun-daun rumpon tersebut.

Alat Bantu Penangkapan , Artikel , Perikanan Tangkap

Global Positioning System (GPS)

Global Positioning System (GPS) adalah sistem radio navigasi dan penentuan posisi dengan menggunakan satelit yang dimiliki dan dikelola oleh Departemen Pertahanan Keamanan Amerika Serikat. Sistem ini didesain untuk memberikan posisi dan kecepatan tiga dimensi dan informasi mengenai waktu secara kontinu. GPS terdiri dari tiga segmen utama, segmen angkasa (space segmen) yang terdiri dari satelit-satelit GPS, segmen sistem kontrol (control segment) yang terdiri dari stasion-stasion pemonitor dan pengontrol satelit, dan segmen pemakai (user segment) yang terdiri dari pemakai GPS termasuk alat-alat penerima dan pengolah sinyal data GPS.

Konsep dasar pada penentuan posisi dengan GPS adalah reseksi (pengikatan kebelakang) dengan jarak, yaitu dengan pengukuran jarak secara simultan ke beberapa satelit GPS yang koordinatnya telah diketahui. Pada pelaksanaan pengukuran penentuan posisi dengan GPS, pada dasarnya ada dua jenis/tipe alat penerima sinyal satelit (receiver) GPS yang dapat digunakan, yaitu :

• Tipe Navigasi digunakan untuk penentuan posisi yang tidak menuntut ketelitian tinggi.

• Tipe Geodetik digunakan untuk penentuan posisi yang menuntut ketelitian tinggi.

Kelebihan penentuan posisi dengan menggunakan GPS antara lain :

1. GPS dapat digunakan setiap saat tanpa bergantung waktu dan cuaca. 
2. GPS dapat digunakan oleh banyak orang pada waktu yang sama dan pemakaiannya tidak bergantung pada batas politik dan alam. 
3. Penggunaan GPS dalam penentuan posisi secara relatif tidak bergantung dengan kondisi topografis daerah survey. 
4. Posisi yang ditentukan dengan GPS mengacu ke datum global yang dinamakan World Geodetic System 1984 (WGS’84). Dengan kata lain posisi yang diberikan oleh GPS akan selalu mengacu ke datum yang sama. 
5. Pemakaian sistem GPS tidak dikenakan biaya, setidaknya sampai saat ini. 

Sistem GPS terdiri dari 24 satelit. Konstelasi 24 satelit GPS tersebut menempati 6 orbit yang mengelilingi bumi dengan sebaran yang telah diatur sedemikian rupa sehingga mempunyai probalitas kenampakan setidaknya 4 satelit yang bergeometri baik dari setiap tempat di permukaan bumi di setiap saat. Satelit GPS mempunyai ketinggian rata-rata di atas permukaan bumi sekitar 20.200 km. Satelit GPS memiliki berat lebih dari 800 kg, bergerak dengan kecepatan sekitar 4 km/detik dan mempunyai periode 11 jam 58 menit. Pengumpulan dan perekaman data penginderaan jauh dapat dilakukan dengan tiga variasi, yaitu distribusi daya, distribusi gelombang bunyi dan ditribusi energi elektromagnetik, namun yang sering digunakan dan paling dikenal adalah penginderaan jauh denngan energi elektromagnetik. Tujuan utama dari penginderaan jauh adalah mengumpulkan data mengenai sumber daya alam dan lingkungan. Informasi tentang objek disampaikan ke pengamat melalui energi elektromagnetik yang berfungsi sebagai pembawa informasi dan penghubung komunikasi. Data yang dihasilkan dari teknik pengindaraan jauh berupa beberapa bentuk citra yang selanjutnya diproses dan diinterpretasikan sehingga diperoleh informasi yang dapat digunakan untuk aplikasi di bidang pertanian, kehutanan, geografi, geologi, perencanaan, arkeologi dan bidang-bidang lain.

Sumber:

Pendidikan dan pelatihan teknis pengukuran dan pemetaan data. Oleh: Danar Guruh Pratomo, ST – Prodi Teknik Geodesi – FTSP – ITS Surabaya agustus 2004

Alat Bantu Penangkapan

Light Fishing

Berawal dari manusia mengetahui cara membuat api, setelah itu manusia juga mengetahui bahwa ada juga ikan yang tertarik akan cahaya. Namun, tidak diketahui juga sejak kapan manusia melakukan penangkapan ikan dengan menggunakan alat bantu cahaya. Seiring dengan berkembangnya teknologi, penggunaan alat bantu cahaya inipun ikut berkembang dalam penangkapan ikan. Dimulai dengan pencahayaan yang sederhana (traditional) hingga menggunakan lampu sebagai sumber cahaya. 

Penangkapan ikan dengan alat bantu cahaya inilah yang disebut dengan light fishing. Sehingga, dapat disimpulan bahwa caha hanyalah merupakan alat bantu dalam suatu operasi penangkapan, yang tentunya berfungsi untuk mengumpulkan ikan dalam suatu area penangkapan (fishing ground) dan kemudian ditangkap dengan menggunakan berbagai jenis alat tangkap. 

Mengapa ikan tertarik akan cahaya?. Pertanyaan inilah yang membuat para ilmuan ingin mengetahui sebenarnya apa yang membuat ikan itu suka dengan cahaya. Pada dasarnya ikan tertarik pada cahaya melalui penglihatan (mata) dan rangsangan melalui otak (pineal region pada otak). Peristiwa tertariknya ikan terhadap cahaya disebut phototaxis (Sudirman and Mallawa 2004). Sehingga dengan demikian ikan yang tertarik dengan cahaya adalah ikan yang mempunyai sifat phototaxis, yang umumnya adalah ikan pelagis dan sebagian ikan demersal. Sedangkan ikan yang tidak tertarik dengan cahaya atau menjauhi cahaya biasa disebut fotophobi, dan adapula yang menyebutnya dengan fototaxis negative. Menurut penelitian tingkah laku ikan, telah diketahui bahwa rangsangan cahaya antara 0,01-0,001 lux, ikan sudah memberikan reaksi, namun ambang cahaya tertinggi untuk mata ikan belum banyak diteliti. Ikan mempunya suatu kemampuan yang mengagumkan untuk dapat melihat pada siang hari dengan kekuatan penerangan ratusan ribu lux dan dalam keadaan gelap sama sekali. Kalau cahaya biru-hijau yuang mampu diterima oleh mata manusia hanya 30% saja, maka mata iikan mampu menerimanya sebesar 75%, sedangkan retina mata dari beberapa jenis ikan dapat menerima sebesar 90%. Jadi bisa disimpulkan bahwa batas ambang cahaya yang mampu diterima ikan lebih tinggi caripada manusia. Cahaya yang masuk ke mata ikan akan diteruskan ke otak pada bagian cone dan rod, yang sangat peka terhadap cahaya. 

Prinsip Light Fishing dan Peristiwa Tertariknya Ikan pada Cahaya. 

Penangkapan ikan dengan menggunakan cahaya sebagai alat bantu untuk mengumpulkan ikan di suatu fishing ground pada umunya hanya memanfaatkan behavior ikan yang tertarik akan cahaya. Menurut Ayodhyoa (1976;1981), bahwa peristiwa tertariknya ikan di bawah cahaya dapat dibagi menjadi 2 macam, yaitu:  

1. Peristiwa langsung, dimana ikan tertarik oleh cahaya lalu berkumpul. Ini tentunya berhubungan langsung dengan peristiwa fototaxis seperti jenis ikan sardinella, kembung, dan layang. 
2. Peristiwa tidak langsung, dimana karena adanya cahaya maka plankton, ikan-ikan kecil dan sebagainya berkumpul, dengan tujuan “feeding”. Beberapa jenis ikan yang termasuk dalam kategori ini adalah seperti ikan tenggiri, cendro, dan lain-lain. 

Dari kedua prinsip di atas, dapat kita ketahui bahwa peristiwa ketertarikan ikan terhadap cahanya itu ada dua macam. Selain untuk mengetahui prinsip-prinsip light fishing, perlu adanya persyaratan-persyratan dalam light fishing demi untuk mengefektifkan proses penangkapan ikan dengan menggunakan alat bantu cahaya. Adapun persyaratan-persyaratan yang perlu diperhatikan adalah lingkungan. Pada perikanan ligh fishing tidak semua kondisi lingkungan dapat dilakukan penangkapan, tetapi harus pada malam hari. Hal ini berhubungan dengan fase bulan, yaitu bulan terang dan bulan gelap. Light fishing hanya efektif pada malam bulan gelap. Kondisi lingkungan lain yang dapat menpengaruhi adalah keadaan perairan, dimana air tidak boleh dalam keadaan keruh, sebaiknya jernih atau tidak terlalu keruh. Karena dapat mempengaruhi daya tembusa cahaya yang semakin pendek. 

Selain memperhatikan kondisi lingkungan, proses penangkapan ikan pun perlu untuk diperhatikan. Persyaratan penangkapan ini sangat perlu untuk diperhatikan, karena sangat berpengaruh terhadapa banyaknya hasil tangkapan.Untuk mengefektifkan sebuah penangkapan, maka seharusnya cahaya mampu menarik ikan pada jarak yang jauh baik secara vertikal, maupun secara horizontal. Setelah berkumpul, hendaknya ikan-ikan itu tetap berada di area cahaya pada jangka waktu yang dibutuhkan untuk melakukan penangkapan. Berbagai jenis alat tangkap mulai dari yang tradisional sampai pada alat tangkap yang modern telah menggunakan cahaya sebagai alat bantu. Jenis-jenis alat tangkap berupa bagan tancap di Perairan Sulawesi Selatan menggunakan lampu strongkin (pressure lamp) sebagai sumber cahaya. Begitu juga purse seine yang beroperasi pada malam hari yang tersebar luas di Perairan Indonesia merupakan alat tangkap yang memanfaatkan cahaya sebagai alat bantu. (Terima Kasih).

Baca juga alat bantu penangkapan RUMPON.

Alat Bantu Penangkapan , Perikanan Tangkap

Pembagian WPP Perairan Indonesia

WPP-RI (Wilayah Pengelolaan Perikanan Republik Indosesia) ini diterbitkan oleh Komisi Nasional Pengkajian Stok Sumberdaya Ikan Laut yang lebih ditujukan untuk memudahkan sistem pendataan sumberdaya ikan, yang selanjutnya digunakan untuk estimasi (pendugaan) stok sumberdaya ikan di laut. Pembagian WPP ini lebih didasarkan pada daerah tempat ikan hasil tangkapan didaratkan di pelabuhan. Pembagian WPP ini sebenarnya telah mengalami beberapa kali perubahan, dimulai dengan pembagian 11 WPP menjadi sembilan WPP  yang ada di Indonesia.

Berikut nama-nama ke-9 WPP-RI  yang ada di Indonesia:

1. Selat Malaka; 
2. Laut Cina Selatan; 
3. Laut Jawa; 
4. Laut Flores dan Selat Makassar;
5. Laut Banda;
6. Laut Arafura;
7. Laut Seram dan Teluk Tomini; 
8. Laut Sulawesi dan Samudera Pasifik; dan 
9. Samudera Hindia.

Tabel keterangan pembagian WPP-RI yang ada di Indonesia.

No	Nama WPP	Terdiri dari
1	Selat Malaka	Provinsi Aceh, Sumatera Utara, dan Riau
2	Laut Cina selatan	Provinsi Kepulauan Riau, Jambi, Sumatera Selatan, Kepulauan Bangka Belitung, Kalimantan Barat.
3	Laut Jawa	Provinsi Lampung, Banten, Jakarta, Jawa Barat, Ja.wa Tengah, Yogyakarta, Jawa Timur, Kalimantan Tengah, Kalimantan Selatan
4	Selat Makasar dan Laut Flores	Provinsi Bali, Nusa Tenggara Timur, Nusa Tenggara Barat, Sulawesi Barat, Sulawesi Selatan, Sulawesi Tenggara
5	Laut Banda	Provinsi Maluku.
6	Laut Arafuru	Laut Aru, dan Laut Timur Timor meliputi Provinsi Papua
7	Laut Maluku	Teluk Tomini dan Laut Seram meliputi Provinsi Sulawesi Tengah, Maluku Utara, dan Papua Barat
8	Laut Sulawesi dan Samudera Pasifik	Provinsi Gorontalo, Sulawesi Utara, Papua dan Kalimantan Timur.
9	Samudera Hindia	Provinsi Aceh,Sumatera Utara, Sumatera Barat, Bengkulu, Lampung, Banten, Jawa Tengah, Jawa Timur, Yogyakarta, Bali, Nusa Tenggara Timur, dan Nusa Tenggara Barat

Perikanan