scholarly journals Effect of underwater visual survey methodology on bias and precision of fish counts: a simulation approach

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5378 ◽  
Author(s):  
Miguel Pessanha Pais ◽  
Henrique N. Cabral
Keyword(s):  
Survey Methodology ◽  
Rotation Speed ◽  
General Point ◽  
Visual Census ◽  
Underwater Visual Census ◽  
Factors Affecting ◽  
Point Counts ◽  
Mobile Species ◽  
Census Methods ◽  
Length Width

Bias in underwater visual census has always been elusive. In fact, the choice of sampling method and the behavioural traits of fish are two of the most important factors affecting bias, but they are still treated separately, which leads to arbitrarily chosen sampling methods. FishCensus, a two-dimensional agent-based model with realistic fish movement, was used to simulate problematic behavioural traits in SCUBA diving visual census methods and understand how sampling methodology affects the precision and bias of counts. Using a fixed true density of 0.3 fish/m2 and a fixed visibility of 6 m, 10 counts were simulated for several combinations of parameters for transects (length, width, speed) and point counts (radius, rotation speed, time), generating trait-specific heatmaps for bias and precision. In general, point counts had higher bias and were less precise than transects. Fish attracted to divers led to the highest bias, while cryptic fish had the most accurate counts. For point counts, increasing survey time increased bias and variability, increasing radius reduced bias for most traits but increased bias in the case of fish that avoid divers. Rotation speed did not have a significant effect in general, but it increased bias for fish that avoid divers. Wider and longer transects and a faster swim speed are beneficial when sampling mobile species, but a narrower, shorter transect with a slow swim is beneficial for cryptic fish.

scholarly journals Pemantauan Kondisi Ikan Karang Menggunakan Metode Reef Check Di Perairan Selat Sempu Malang Selatan

2017 ◽  
Vol 3 (2) ◽  
pp. 171 ◽  
Author(s):  
Oktiyas Muzaky Luthfi ◽  
Riza Alifia ◽  
Sherla Rizqia Putri ◽  
Firmina Bethrix Dasi ◽  
Bramastrha Artha Putra ◽  
...  
Keyword(s):  
Coral Reefs ◽  
Reef Fish ◽  
Human Activities ◽  
Management System ◽  
The Other ◽  
Visual Census ◽  
Underwater Visual Census ◽  
Research Site ◽  
The Family ◽  
Length Width

Reef Check is an activity to find out the condition of coral reefs and its surrounding ecosystems be then described and categorized its healthiness. The island of Java is one of the Islands in Indonesia that has lots of beaches, especially for East Java, here they have several areas that has become our research site in Sempu Strait, Sendang Biru, South Malang they are called Teluk Semut, Watu Meja, and Waru-waru. Underwater Visual Census (UVC) was used as a method for this research to identify reef fish in a transect of 100 x 5 x 5m scale in (Length, Width, and Height). Results shows several fishes was used to identify yet the family of  Chaetodontidae with mean abundance 8 in Teluk Semut 1 station, 2.25 in Teluk Semut 2 station, 12.5 in Rumah Ikan station, & 13.5 in Watu Meja station. Watu Meja and Fish Apartment station shows higher mean abundance than other station, this indicates coral reefs ecosystem in this station have a better health & condition compare to the other stations. Results for family family Haemulidae, Snapper and Grouper shows low mean abundance, that indicates overfishing on Sempu Strait, South Malang. In other cases, the purposes of Reef Check is to determine the extents of human activities and its impact against the distribution and the healthiness of coral reefs in the area. For further extent, there has been still indications toward its management system yet fisheries potential in certain areas for this research.

Asosiasi ikan pada terumbu buatan di Teluk Tahuna Kabupaten Kepulauan Sangihe

2016 ◽  
Vol 2 (2) ◽  
Author(s):  
Wenseslaus Fransiscus Makawaehe ◽  
Lefrand Manoppo ◽  
Revols D.Ch. Pamikiran
Keyword(s):  
Visual Census ◽  
Underwater Visual Census ◽  
Scuba Divers

Minimnya pengetahuan tentang ekologi terumbu buatan merupakan inti masalah perdebatan penggunaannya dalam manajemen sumberdaya perikanan; dan membatasi aplikasi habitat buatan tersebut sebagai alat mitigasi pada berbagai kerusakan lingkungan. Pemahaman ekologi yang lebih baik akan menuntun pada pembuatan desain dan penggunaan struktur buatan secara lebih efektif dan efisien. Hal ini juga akan menjawab pertanyaan tentang manfaat konstruksi habitat buatan pada berbagai kondisi lingkungan. Asosiasi ikan di terumbu buatan bervariasi, namun perlu dilakukan perbandingan jenis ikan yang berasosiasi pada saat air pasang dan air surut. Oleh karena itu penelitian ini bertujuan untuk Membandingkan struktur asosiasi ikan di terumbu buatan pada saat air pasang naik dan pasang surut di perairan Teluk Tahuna. Penelitian ini dilakukan di perairan Teluk Tahuna, Kabupaten Kepulauan Sangihe pada bulan April–Juni 2015; yang didasarkan pada metode deskriptif. Asosiasi ikan di terumbu buatan diamati dengan teknik Underwater visual census (UVC) oleh dua orang SCUBA divers sebanyak 4 kali. Kelimpahan spesies ikan di terumbu buatan dianalisis dengan indeks keragaman dan indeks dominansi. Berdasarkan jumlah individu total ikan yang berasosiasi dengan terumbu buatan, maka nilai tertinggi terdapat pada bulan purnama saat pasang tertinggi (156 ekor), kemudian diikuti bulan kuartir pasang tertinggi (120 ekor), bulan purnama surut terendah (107 ekor) dan bulan kuartir surut terendah (103 ekor). Keanekaragaman spesies ikan, baik pada bulan kuartir maupun pada bulan purnama masih tergolong sedang dan dominansi spesies tergolong rendah

scholarly journals Complementarity of Rotating Video and Underwater Visual Census for Assessing Species Richness, Frequency and Density of Reef Fish on Coral Reef Slopes

PLoS ONE ◽  
2014 ◽  
Vol 9 (1) ◽  
pp. e84344 ◽  
Author(s):  
Delphine Mallet ◽  
Laurent Wantiez ◽  
Soazig Lemouellic ◽  
Laurent Vigliola ◽  
Dominique Pelletier
Keyword(s):  
Species Richness ◽  
Coral Reef ◽  
Reef Fish ◽  
Visual Census ◽  
Underwater Visual Census

scholarly journals eDNA metabarcoding as a biomonitoring tool for marine protected areas

2020 ◽  
Author(s):  
Zachary Gold ◽  
Joshua Sprague ◽  
David J. Kushner ◽  
Erick Zerecero ◽  
Paul H. Barber
Keyword(s):  
Protected Areas ◽  
Fish Species ◽  
Marine Protected Areas ◽  
Marine Reserve ◽  
Marine Ecosystem ◽  
Site Occupancy ◽  
Visual Methods ◽  
Visual Census ◽  
Underwater Visual Census ◽  
Promising Alternative

AbstractMonitoring of marine protected areas (MPAs) is critical for marine ecosystem management, yet current protocols rely on SCUBA-based visual surveys that are costly and time consuming, limiting their scope and effectiveness. Environmental DNA (eDNA) metabarcoding is a promising alternative for marine ecosystem monitoring, but more direct comparisons to visual surveys are needed to understand the strengths and limitations of each approach. This study compares fish communities inside and outside the Scorpion State Marine Reserve off Santa Cruz Island, CA using eDNA metabarcoding and underwater visual census surveys. Results from eDNA captured 76% (19/25) of fish species and 95% (19/20) of fish genera observed during pairwise underwater visual census. Species missed by eDNA were due to the inability of MiFish 12S barcodes to differentiate species of rockfishes (Sebastes, n=4) or low site occupancy rates of crevice-dwelling Lythrypnus gobies. However, eDNA detected an additional 30 fish species not recorded in paired visual surveys, but previously reported from prior visual surveys, highlighting the sensitivity of eDNA. Significant variation in eDNA signatures by location (50m) and site (~1000m) demonstrates the sensitivity of eDNA to address key questions such as community composition inside and outside MPAs. Interestingly, eDNA results recorded higher species richness outside the MPA while visual surveys observed the opposite pattern. This result is likely caused by swamping effects of high fish abundance in MPAs that reduce detection probabilities of pelagic and intertidal taxa. Results demonstrate the utility of eDNA metabarcoding for monitoring marine ecosystems, providing an important complementary tool to visual methods.

scholarly journals ANALISIS KESESUAIAN PERAIRAN BAGI KEGIATAN WISATA BAHARI SNORKLING DAN SELAM DI PERAIRAN PULAU NUSALAUT KABUPATEN MALUKU TENGAH

2019 ◽  
Vol 11 (3) ◽  
pp. 653-666
Author(s):  
Terry Indrabudi ◽  
Arif Seno Adji ◽  
Widhya Nugroho Satrioajie ◽  
Robert Alik
Keyword(s):  
Life Form ◽  
Visual Census ◽  
Underwater Visual Census

Maluku memiliki sumberdaya laut yang sangat besar, baik sumberdaya hayati maupun nir-hayati termasuk potensi wisata bahari yang menjadi prioritas pemerintah untuk dikembangkan. Namun pada kenyataannya, perkembangan wisata bahari di Maluku masih menghadapi berbagai kendala, yaitu menentukan lokasi yang layak untuk dijadikan tujuan wisata. Penelitian ini bermaksud untuk melihat tingkat kesesuaian wisata khususnya wisata snorkling dan selam di perairan Pulau Nusalaut. Pengambilan sampel dilakukan pada tahun 2014 dan 2015 di 6 (enam) lokasi yang berbeda.  Pengambilan data karang menggunakan metoda LIT (Line Intecept Trancect) dan dianalisis menggunakan "Life Form Program". Pengamatan ikan karang dilakukan dengan Underwater Visual Census (UVC) dan transek. Parameter lingkungan diambil dengan cara pengukuran langsung dilapangan. Terumbu karang dikategorikan dalam kondisi ”Baik” dan ”Sangat Baik” dengan persentase tutupan karang antara 58,54-77%. Sebanyak 217 jenis karang batu yang termasuk ke dalam 52 genera dari 16 famili menempati rataan terumbu. Keanekaragaman ikan karang berada pada kondisi yang cukup baik dengan indeks keanekaragaman berkisar antara 3,05-4,09. Setidaknya terdapat 2.838 individu ikan karang dari 25 famili dan 170 jenis, terbagi dalam kelompok ikan indikator sebanyak 6%, ikan mayor 67% dan ikan target 27%. Kecerahan perairan berkisar antara 8-12 m dengan kecepatan arus antara 1,6-18,5 m/s. Berdasarkan hasil analisis kesesuaian wisata, seluruh lokasi penelitian dikategorikan “Sangat Sesuai” untuk dijadikan tujuan wisata snorkling maupun selam dengan Indeks Kesesuaian Wisata antara 81,25-95,83%.

scholarly journals HUBUNGAN ANTARA KOMPOSISI IKAN TARGET DAN PRESENTASE TUTUPAN KARANG HIDUP DI KEPULAUAN KEI KECIL, MALUKU

2020 ◽  
Vol 26 (3) ◽  
pp. 147
Author(s):  
Ana Faricha ◽  
Isa Nagib Edrus ◽  
Rizkie Satriya Utama ◽  
Ahmad R. Dzumalex ◽  
Abdullah Salatalohi ◽  
...  
Keyword(s):  
Coral Reef ◽  
Reef Fishes ◽  
Average Density ◽  
Species Variation ◽  
Live Coral ◽  
Visual Census ◽  
Underwater Visual Census ◽  
Ecological Values ◽  
Average Biomass ◽  
The Relationship

Ikan terumbu karang memiliki peranan penting baik secara ekonomi maupun ekologi, namun kondisi terumbu karang termasuk di perairan Indonesia yang menjadi habitat utama ikan karang mengalami degradasi. Penelitian ikan karang sudah banyak dilakukan, namun di Indonesia kondisi habitat ikan karang memiliki karakter yang berbeda-beda. Tujuan penelitian ini adalah untuk mengetahui hubungan antara komposisi ikan karang target dan tutupan karang hidup. Penelitian ini dilakukan pada bulan Oktober 2019 di Kepulauan Kei Kecil, Maluku. Metode yang digunakan adalah UVC (Underwater Visual Census) untuk data ikan karang dan UPT (Underwater Photo Transect) untuk mengkaji tutupan karang hidup. Hasil pengamatan menunjukkan bahwa terdapat 130 spesies ikan karang target yang mewakili 19 famili, dengan variasi jenis ikan target antar lokasi pengamatan berkisar antara 25-66 spesies. Kepadatan rata-rata ikan karang target sebesar 8.811 ± 4.107 Ind/ha, dan biomassa rata-rata 1.335 ± 899 Kg/ha. Komposisi ikan karang target yang memiliki kedekatan dengan tutupan karang hidup yaitu famili Siganidae, Serranidae, Lutjanidae, Holocentridae, dan Pomacentridae. Akan tetapi hubungan tersebut rendah, dan kemungkinan besar ada faktor lain yang mempengaruhi. Reef fishes have an important economic and ecological values. However, the coral reef of the globe including in the most of the Indonesian waters which is the vital habitat for reef fishes is degraded. Study on the reef fishes is an abundance, while the habitat characteristic of reef fishes in Indonesian waters has a differences. The aim of this study is to determine the relationship between the target reef fishes compositions and the percentage live coral covers. This study was carried out in October 2019 at the Kei Kecil islands, Maluku. The method used in this study is UVC (Underwater Visual Census) for collecting the reef fishes data, and the UPT (Underwater Photo Transect) for assessing the live coral coverage. The result shows that there are about 130 fishes, which representing 19 families, with species variation ranges from 25 to 66 species among the observation sites. The average density of target fishes was about 8.811 ± 4.107 Ind/ha, whereas the average biomass of target fishes was 1,335 ± 899 Kg/ha. The target reef fishes compositions that has relation with live coral covers is family Siganidae, Serranidae, Lutjanidae, Holocentridae, and Pomacentridae. However, this relationship is weak, and may influenced by other factors.

Population estimates and size structure of Plectropomus leopardus (Pisces : Serranidae) in relation to no-fishing zones: mark-release-resighting and underwater visual census

2000 ◽  
Vol 51 (3) ◽  
pp. 221 ◽  
Author(s):  
D. C. Zeller ◽  
G. R. Russ
Keyword(s):  
Great Barrier Reef ◽  
Population Size ◽  
Size Structure ◽  
Barrier Reef ◽  
Visual Census ◽  
Underwater Visual Census ◽  
Coral Trout ◽  
Population Size Estimates ◽  
Lizard Island ◽  
Plectropomus Leopardus

A mark–release–resighting (MRR) technique was used to estimate population size of the coral trout, Plectropomus leopardus, on coral reefs fringing Lizard Island, Great Barrier Reef, Australia. Fish were captured by hook-and-line fishing, and marked with individual freeze-brand numbers in August 1995. An underwater visual census (UVC) technique was used during September and October 1995 both for resighting of marked fish and to make an independent estimate of fish density and thus population size. The study area was 750 966 m2 . The UVC sampled 154 000 m2 (20.5%) of this area. Six different methods of analysis of MRR gave similar population size estimates (e.g. Petersen 12 873; 95% CI 9989–15 754) extrapolated to the 4.5 million-m2 reef area from datum to 20-m depth around Lizard Island. UVC gave a population size estimate (24 182; 95% CI 21 860–26 504) twice that of MRR. The lower estimate derived from MRR may be the result of tag-induced mortality, or of the relative difficulty in discriminating between marked and unmarked trout by UVC. This is only the second estimate of population size of coral trout on an area of the Great Barrier Reef.

Sign in / Sign up

Export Citation Format

Share Document