Compensating for length biases in underwater visual census of fishes using stereo video measurements

2015 ◽  
Vol 66 (3) ◽  
pp. 286 ◽  
Author(s):  
Tom Davis ◽  
David Harasti ◽  
Stephen D. A. Smith
Keyword(s):  
Marine Protected Areas ◽  
Reef Fishes ◽  
Fish Length ◽  
Correction Factors ◽  
Visual Census ◽  
Underwater Visual Census ◽  
Observer Bias ◽  
Stereo Video ◽  
Non Destructive ◽  
Specific Correction

Underwater visual census (UVC) is a widely used technique for estimating species richness, abundance, and lengths of reef fishes. The technique has the advantage of being non-destructive, and can therefore be used for monitoring in marine protected areas. However, acquisition of robust data using UVC is reliant on the ability of individual divers to accurately identify fish, and estimate their lengths. Both of these variables can be affected by observer bias, which may also differ among observers. This study examines a technique with the potential to quantify and correct for observer bias in individual divers. We used simultaneous diver-operated stereo video and underwater visual census surveys, and compared the results to generate diver-specific correction factors. These correction factors were subsequently applied in additional estimates of fish length, with measurable improvement in the accuracy of the data.

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 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.

scholarly journals Tutupan karang dan komposisi ikan karang didalam dan luar kawasan konservasi pesisir timur Pulau Weh, Sabang

DEPIK ◽  
2014 ◽  
Vol 3 (2) ◽  
Author(s):  
Riany Hastuty ◽  
Yonvitner . ◽  
Luky Adrianto
Keyword(s):  
Protected Areas ◽  
Reef Fish ◽  
Marine Protected Areas ◽  
Conservation Areas ◽  
Visual Census ◽  
Marine Protect Area ◽  
Underwater Visual Census ◽  
Protect Area ◽  
Reef Fish Species ◽  
Composition Point

Abstract. The study was conducted onApril to October 2013 in marine protected areas of Weh Island. The samplings were done at10 siteswhere 6 sitesare situatedinside of conservation areas, while 4 sites are situated outside of conservation areas. The purpose ofthis study was to evaluate coral covers andreef fish composition. Point intersept transect(PIT), underwater visual census (UVC) and fish catches were used to examine coral covers, abudance and biomass of reef fish. The results showed that average of coral covers, abudance and biomass of target fishes inside conservation were 54%, 1,662 ind/ha and 408.78 kh/ha, respectively, while than outside conservation was 33.05%, 1,058 ind/ha and 307.77 kg/ha, respectively. Total of reef fish species and the catch were increased from previous years, for example there are 60 species in 2010 and it was increased to 83 species in 2013. In addition the fishermen catches were increased slightly from 3.03 kg/trip in 2008 to 3.6 kg/trip in 2013. It is concluded that the coral condition and reef fish composition in the conservation are much better compared to outside of conservation areas.Keywords : Marine protect area; reef fish; Weh Island Abstrak. Penelitian ini dilakukan pada April sampai Oktober 2013 di Kawasan Konservasi Perairan Pesisir Timur Pulau Weh yang terdiri dari 10 stasiun dimana 6 stasiun berada didalam kawasan konservasi dan 4 stasiun diluar kawasan konservasi.Penelitian ini bertujuan untuk menilai persentase tutupan karang dan komposisi ikan karang. Sampling menggunakan transek titik dan underwater visual sensus (UVC) dan hasil tangkapan.Hasil penelitian menunjukkan bahwa rata-rata kondisi tutupan karang, kelimpahan dan biomassa ikan target dikawasan konservasi yaitu 54%, 1.662 ind/ha dan 408,78 kg/ha, secara berurutan, sedangkan diluar kawasan konservasi adalah 33,05%, 1.058 ind/ha dan 307,77 kg/ha biomassa ikan target.Jumlah jenis ikan karang di kawasan konservasi meningkat, yaitu 60 jenis tahun 2010 menjadi 83 jenis pada tahun 2013 dan rata-rata hasil tangkapan tahun 2008 yaitu 3,03 kg/trip dan tahun 2013 yaitu 3,6 kg/trip. Dapat disimpulkan bahwa kondisi karang dan komposisi jenis dan ukuran ikan lebih baik di dalam kawasan konservasi berbanding diluar kawasan.Kata kunci: Kawasan Konservasi; Ikan karang; Pulau Weh

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

PLoS ONE ◽  
2021 ◽  
Vol 16 (2) ◽  
pp. e0238557
Author(s):  
Zachary Gold ◽  
Joshua Sprague ◽  
David J. Kushner ◽  
Erick Zerecero Marin ◽  
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

Monitoring 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 23 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 (50 m) and site (~1000 m) demonstrates the sensitivity of eDNA to address key questions such as community composition inside and outside MPAs. Results demonstrate the utility of eDNA metabarcoding for monitoring marine ecosystems, providing an important complementary tool to visual methods.

Small home range in southern Australia's largest resident reef fish, the western blue groper (Achoerodus gouldii): implications for adequacy of no-take marine protected areas

2012 ◽  
Vol 63 (6) ◽  
pp. 552 ◽  
Author(s):  
Simon Bryars ◽  
Paul Rogers ◽  
Charlie Huveneers ◽  
Nicholas Payne ◽  
Ian Smith ◽  
...  
Keyword(s):  
Home Range ◽  
Protected Areas ◽  
Marine Protected Areas ◽  
Site Fidelity ◽  
Reef Fishes ◽  
Fish Length ◽  
Narrow Strip ◽  
Permanent Resident ◽  
High Site ◽  
Small Home Range

No-take marine protected areas (MPAs) represent an effective biodiversity conservation tool for a range of species including resident reef fishes that are intrinsically vulnerable to overfishing and other localised impacts. The western blue groper (Achoerodus gouldii) is the largest permanent-resident reef teleost in southern Australian waters and has the second-oldest recorded age of any labrid at 70 years. Acoustic telemetry was used to investigate whether adult A. gouldii can be effectively protected within adequately sized no-take MPAs. Ten passive acoustic receivers tracked the movements of 15 A. gouldii individuals (69–112-cm total length; 7–31-kg weight) at a site off north-western Kangaroo Island, South Australia. Most of the fish displayed high site fidelity (91–100% residence time for 10 of the 11 fish with useful data) for a narrow strip of fringing coastal reef (~1-km length by ~40-m width) throughout a 12-month period. Mean home-range along-shore length and area were estimated at 1076 ± 83 m (s.e.), and 45 188 ± 3497 m2, respectively (n = 11 fish with useful data). Comparison with other resident temperate-reef teleosts indicated no relationship between fish length and home-range area, and that A. gouldii has a relatively small home range. The high site fidelity and small home range of adult A. gouldii individuals makes localised populations amenable to a high level of protection within no-take MPAs.

scholarly journals Typhoon-driven Coral-Algal Phase-shifts in Southern Negros Oriental, Philippines

2014 ◽  
Vol 2 (3) ◽  
Author(s):  
Abner A Bucol
Keyword(s):  
Phase Shift ◽  
Marine Protected Areas ◽  
Protected Area ◽  
Marine Protected Area ◽  
Control Site ◽  
Slow Recovery ◽  
Visual Census ◽  
Underwater Visual Census ◽  
Total Fish ◽  
Fish Species Composition

An underwater visual census (UVC) conducted to assess the biophysical conditions of the two marine protected areas (Antulang Marine Protected Area and Andulay Marine Protected Area) in Siaton, Negros Oriental revealed slow recovery from severe damage resulting from Typhoon Sendong in December 2011, suggestive of “coral-algal phase-shift”. Live hard coral (LHC) cover was consistently poor in the survey sites (2.25±0.78 % in Antulang Marine Protected Area; 1.25±0.50 % in the Control Site; and 3.33±0.17 % in Andulay Marine Protected Area) following destruction by the typhoon and colonization of algae (between 37-53%), dominated by Bornetella oligospora. Mean total fish biomass (including fusiliers and schooling juvenile Caranx sexfasciatus) was highest in Antulang Marine Protected Area at 70.60±28.07 kg/500m2 (equivalent to 141.21±56.14 tonne/km2) while lowest in Andulay Marine Protected Area at 9.83±4.32 kg/500m2. Mean total fish density was highest in Antulang Marine Protected Area at 597.0±114.7 fish/500m2 followed by the Control Site with 361.7±159.0 fish/500 m2, while Andulay Marine Protected Area had 200.7±31.6 fish/500m2. Fish species composition was slightly altered, i.e. decline in coral-dependent species such as damselfishes. Keywords: coral reef, macroalgae, phase-shift, resilience, recovery, typhoon

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