Comparison of condition factors of skipjack tuna (Katsuwonus pelamis) associated or not with floating objects in an area known to be naturally enriched with logs

2014 ◽  
Vol 71 (3) ◽  
pp. 472-478 ◽  
Author(s):  
Marianne Robert ◽  
Laurent Dagorn ◽  
Nathalie Bodin ◽  
Fabrice Pernet ◽  
Eve-Julie Arsenault-Pernet ◽  
...  
Keyword(s):  
Skipjack Tuna ◽  
Short Term ◽  
Free Swimming ◽  
Katsuwonus Pelamis ◽  
Meeting Point ◽  
Mozambique Channel ◽  
Alternative Hypotheses ◽  
Floating Objects ◽  
The Impact ◽  
Fish Aggregating Devices

In an area that has barely been modified by fish aggregating devices (FADs) (e.g., the Mozambique Channel, known to be naturally enriched with logs, with few FADs), we found that the condition of skipjack tuna (Katsuwonus pelamis) associated with floating objects was lower than those in free-swimming schools. As this result was found in an area that mimics the environmental state prior to the use of FADs, it questions the interpretation of previous studies where such a difference has been interpreted to reflect the impact of extensive FAD deployment on tunas. It is possible that before the use of FADs, tunas associated with logs were also in poorer condition than tunas in free-swimming schools. Our results suggest that the evolutionary reason for which tunas associated with floating objects might not relate to short-term trophic benefit, and alternative hypotheses (e.g., the meeting point hypothesis) are discussed to explain this result.

scholarly journals Quantifying the increase in fishing efficiency due to the use of drifting FADs equipped with echosounders in tropical tuna purse seine fisheries

2020 ◽  
Author(s):  
Gwenaëlle Wain ◽  
Loreleï Guéry ◽  
David Michael Kaplan ◽  
Daniel Gaertner
Keyword(s):  
New Technology ◽  
Recent Change ◽  
Purse Seine ◽  
Catch Per Unit Effort ◽  
Katsuwonus Pelamis ◽  
Thunnus Obesus ◽  
Efficiency Increase ◽  
Tropical Tuna ◽  
Floating Objects ◽  
The Impact

Abstract Numerous pelagic species are known to associate with floating objects (FOBs), including tropical tunas. Purse seiners use this behaviour to facilitate the capture of tropical tunas by deploying artificial drifting fish aggregating devices (dFADs). One major recent change has been the integration of echosounders in satellite-tracked GPS buoys attached to FOBs, allowing fishers to remotely estimate fishable biomass. Understanding the effects of this new technology on catch of the three main tuna species (yellowfin tuna, Thunnus albacares; bigeye tuna, Thunnus obesus; and skipjack tuna, Katsuwonus pelamis) is important to accurately correct for this change in catch-per-unit-effort (CPUE) indices used for stock assessments. We analysed catch data from the French purse seine fleet for the period 2010–2017 in the Indian Ocean to assess the impact of this fleet’s switch to echosounder buoys around 2012. Results indicate that echosounders do not increase the probability a set will be succesful, but they have a positive effect on catch per set, with catches on average increasing by ≈2−2.5 tonnes per set (≈10%) when made on the vessel's own dFADs equipped with an echosounder buoy. Increases were due to a decrease in sets below ≈25 tonnes and an increase in those greater than ≈25 tonnes, with a non-linear transition around this threshold. This increase explains the considerable investment of purse seiners in echosounder buoys, but also raises concerns about bias in stock size estimates based on CPUE if we do not correct for this fishing efficiency increase.

scholarly journals Efektivitas penggunaan rumpon sebagai daerah penangkapan ikan di Perairan Pusong Kota Lhokseumawe

DEPIK ◽  
2018 ◽  
Vol 7 (2) ◽  
pp. 119-126
Author(s):  
Makwiyah A. Chaliluddin ◽  
Ratna M. Aprilla ◽  
Junaidi M. Affan ◽  
Abdullah A. Muhammadar ◽  
Heri Rahmadani ◽  
...  
Keyword(s):  
Purse Seine ◽  
Fishing Ground ◽  
Survey Method ◽  
Skipjack Tuna ◽  
Tuna Fish ◽  
Katsuwonus Pelamis ◽  
Direct Sampling ◽  
Euthynnus Affinis ◽  
Fish Aggregating Devices

The existence of fish aggregating devices (FADs) in a waters is able to establish a new fishing ground that potential waters. FADs are able to attract the attention of the gathering of fishes and other aquayic organisms around it, increasing the density of fish around FADs can increase the chances of successful catching operation, and therefore the FADs has benefited significantly to increase the capture fishery production significantly. The purposes of the research were to evaluate the catching composition of purse seine production  using FADs and non FADs, and to examine the fectiveness of FADs. This research was conducted on February 1 - 28, 2018 located at Pusong Waters, Lhokseumawe City. The survey  method was used in this study. The direct sampling by following the fisherman in fishing activities was performed both the purse seine with FADs and no FADs. Total purse seine catches during the research were 4,320 kg consisting of Long Jawed Mackerel (Rastrelliger sp.) 1,280 kg (29.63%), Decapterus Fish ( Decapterus sp.) 350 kg (8,107%), skipjack tuna (Katsuwonus pelamis) 845 kg (19.56 %), tuna fish (Euthynnus affinis) 720 kg (16.67%), Torpedo scad (Megalaspis cordyla) 300 kg (6.94%), Queenfish 140 kg (3.24%), and starry triggerfish (Abalistes stellaris) 685 kg (15.86%). It was concluded that the purse seine used FADs is more effective  compared to the a purse seine that does not use FADs.Keberadaan rumpon di suatu perairan mampu menarik perhatian berkumpulnya ikan dan organisme lain disekitarnya, sehingga dapat meningkatkan hasil tangkapan ikan. Penelitian ini bertujuan untuk menganalisis komposisi hasil tangkapan purse seine yang menggunakan rumpon dan purse seine yang tidak menggunakan rumpon, dan menilai efektivitas rumpon dalam mengumpulkan ikan. Penelitian ini dilaksanakan pada 01 - 28 Februari 2018 bertempat di Perairan Pusong, Kota Lhokseumawe. Metode penelitian yang digunakan adalah metode survei, yaitu dengan mengikuti nelayan dalam kegiatan penangkapan ikan, baik nelayan purse seine yang menggunakan rumpon dan nelayan purse seine yang tidak menggunakan rumpon. Data ikan hasil tangkapan yang diperoleh dihitung jumlah ikan hasil tangkapan dan diidentifikasi spesies ikan dan selanjutnya dibandingkan dengan hasil tangkapan nelayan yang menggunakan rumpon dan ikan hasil tangkapan nelayan yang tidak menggunakan rumpon. Total hasil tangkapan purse seine selama penelitian sebanyak 4.320 kg terdiri dari kembung (Rastrelliger sp.) 1.280 kg (29,63%), layang (Decapterus sp.) 350 kg (8,107%), cakalang (Katsuwonus pelamis) 845 kg (19,56%), tongkol (Euthynnus affinis) 720 kg (16,67 %), tegang ekor/tetengkek (Megalaspis cordyla) 300 kg (6,94 %), talang/daun bamboo (Scomberoides lysan) 140 kg (3,24%), dan ayam-ayam (Abalistes stellaris) 685 kg (15,86 %).  Dari kedua jenis kegiatan penangkapan ikan tersebut, maka purse seine menggunakan rumpon lebih efektif dibandingkan purse seine yang tidak menggunakan rumpon sebagai daerah penangkapan ikan.

scholarly journals STATUS KEBERLANJUTAN PERIKANAN HUHATE BERDASARKAN ASPEK BIOLOGI DI PPI DUFA-DUFA KOTA TERNATE

1970 ◽  
Vol 10 (1) ◽  
pp. 117-116
Author(s):  
Irham . ◽  
Amirul Karman ◽  
Kusdi Hi Iksan
Keyword(s):  
Size Structure ◽  
Economic Value ◽  
Fork Length ◽  
Pelagic Fish ◽  
Fishing Ground ◽  
Skipjack Tuna ◽  
Katsuwonus Pelamis ◽  
Strategic Location ◽  
Catch Composition ◽  
Fish Aggregating Devices

ABSTRACTTernate Island lies in a strategic location as it is situated in the middle of  the main fishing ground for skipjack (Katsuwonus pelamis) fishing using pole and line (huhate) and fish aggregating devices (FADs). As typical pelagic fish, skipjack that is gathered near the water surface is the younger fish, likewise the ones which are caught around FADs. Therefore, this fishing method has caused serious problem due to the domination of young fish and increasing bycatch and discard. The objective of this research is to analyze the size structure of the fork length, appropriate size for catching, catch composition, bycatch and discard level. Pole and line catch samples were collected in 3 months fromMay to July 2018. The results show that in average, skipjack tuna caught in the study location was undersize. The total catch is predominantly targeted fish which has a higher economic value compared to bycatch and discarded fish. Even though bycatch in the pole and line fisheries are low, reduction efforts are still required. which can be done by sorting bycatch and unwanted fish then discard it into the sea when the fish is still alive.Keywords: biology, pole and line, sustainability status, Ternate City ABSTRAKPosisi Pulau Ternate sangat strategis karena berada di tengah perairan yang menjadi daerah operasi penangkapan cakalang (Katsuwonus pelamis) dengan alat tangkap huhate (pole and line) yang dibantu dengan penggunaan rumpon. Sebagaimana ikan pelagis lainnya,  ikan-ikan cakalang yang berkumpul di lapisan permukaan air cenderung tergolong ikan-ikan muda. Oleh karena itu, cakalang yang tertangkap di sekitar rumpon juga cenderung ikan-ikan yang masih muda. Fenomena ini menyebabkan munculnya sebuah masalah besar, yaitu dominasi ikan-ikan muda, selain itu juga sering tertangkap ikan yang bukan target tangkap yang terdiri dari bycatch dan discards. Tujuan dari penelitian ini adalah menganalisis struktur ukuran panjang cagak dan ukuran cakalang layak tangkap, komposisi hasil tangkapan, persentase bycatch dan discards. Sampel hasil tangkapan huhate dikumpulkan selama 3 bulan (Mei sampai Juli 2018). Hasil penelitian menunjukkan bahwa rataan cakalang di lokasi penelitian didominasi ukuran belum layak tangkap. Total hasil tangkapan didominasi ikan target, sementara itu bycatch yang tertangkap memiliki nilai ekonomis yang baik dan tidak ditemukan discards. Walaupun bycatch pada perikanan huhate rendah namun usaha-usaha untuk meminimumkan tetap perlu dilakukan. Salah satu usaha yang bisa dilakukan adalah menyortir hasil tangkapan, ada apabila ada ikan yang akan dibuang ke laut, dilakukan dalam keadaan masih hidup.Kata Kunci: Biologi, huhate (pole and line), status keberlanjutan, Kota Ternate

Modeling Effects of FADs and Islands on Movement of Skipjack Tuna (Katsuwonus pelamis): Estimating Parameters from Tagging Data

1994 ◽  
Vol 51 (12) ◽  
pp. 2642-2653 ◽  
Author(s):  
P. Kleiber ◽  
J. Hampton
Keyword(s):  
Solomon Islands ◽  
Fish Movement ◽  
Skipjack Tuna ◽  
Movement Model ◽  
Katsuwonus Pelamis ◽  
Movement Parameters ◽  
Fish Aggregating Devices

From an experiment with ordinary dart tags, we have found evidence of the effect of fish-aggregating devices (FADs) and of islands on the movements of skipjack tuna (Katsuwonus pelamis) around the Solomon Islands. By fitting a fish movement model to the tag data, we were able to estimate mortality and movement parameters (including diffusivity), parameters of a function that models FAD attraction, and a separate parameter of island attraction. Diffusivity was high enough to effectively distribute fish throughout the island archipelago (approximately 150 000 km2) within a few months. Estimates of FAD parameters indicate that the presence of up to four or five FADs in an area approximately 50 × 50 km can reduce the propensity for skipjack to leave that area by approximately 50%, but that deploying additional FADs in such an area does not significantly increase their effectiveness in holding skipjack. Estimates of the island attraction parameter imply that the propensity of skipjack for movement away from the archipelago is less than half the propensity for movement within it.

scholarly journals Identification of skipjack tuna (Katsuwonus pelamis) pelagic hotspots applying a satellite remote sensing-driven analysis of ecological niche factors: A short-term run

PLoS ONE ◽  
2020 ◽  
Vol 15 (8) ◽  
pp. e0237742
Author(s):  
Robinson Mugo ◽  
Sei-Ichi Saitoh ◽  
Hiromichi Igarashi ◽  
Takahiro Toyoda ◽  
Shuhei Masuda ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Satellite Remote Sensing ◽  
Ecological Niche ◽  
Skipjack Tuna ◽  
Short Term ◽  
Katsuwonus Pelamis

A Newspaper’s Effect on the Strength of Automatic Associations in Memory

2012 ◽  
Vol 24 (1) ◽  
pp. 1-8 ◽  
Author(s):  
Florian Arendt
Keyword(s):  
Treatment Group ◽  
Term Effect ◽  
Control Group ◽  
Implicit Measure ◽  
Short Term ◽  
Short Term Treatment ◽  
Short Term Effect ◽  
Automatic Associations ◽  
Foreign Nationality ◽  
The Impact

A test was done to see if reading a newspaper which consistently overrepresents foreigners as criminals strengthens the automatic association between foreign country and criminal in memory (i.e., implicit cultivation). Further, an investigation was done to find out if reading articles from the same newspaper produces a short-term effect on the same measure and if (1) emotionalization of the newspaper texts, (2) emotional reactions of the reader (indicated by arousal), and (3) attributed text credibility moderate the short-term treatment effect. Eighty-five participants were assigned to one of three experimental conditions. Participants in the control group received short factual crime texts, where the nationality of the offender was not mentioned. Participants in the factual treatment group received the same texts, but the foreign nationality was mentioned. Participants in the emotionalized treatment group received emotionalized articles (i.e., texts which are high in vividness and frequency) covering the same crimes, with the foreign nationality mentioned. Supporting empirical evidence for implicit cultivation and a short-term effect was found. However, only emotionalized articles produced a short-term effect on the strength of the automatic association, indicating that newspaper texts must have a minimum of stimulus intensity to overcome an effect threshold. There were no moderating effects of arousal or credibility pertaining to the impact on the implicit measure. However, credibility moderated the short-term effect on a first-order judgment (i.e., estimated frequency of foreigners of all criminals). This indicates that a newspaper’s effect on the strength of automatic associations is relatively independent from processes of propositional reasoning.

Diatoms in the Amur Bay sediments (Sea of Japan) and the impact of typhoons on their accumulation over the last 2000 years

2019 ◽  
pp. 252-256
Author(s):  
Irina A. Prushkovskaya ◽  
Ira B. Tsoy
Keyword(s):  
Sea Of Japan ◽  
Short Term ◽  
Catastrophic Events ◽  
Bromine Content ◽  
Amur Bay ◽  
The Impact

The study of diatoms in the sediments of the Amur Bay (Sea of Japan), formed over the last 2000 years, showed that the sharp short-term drops in the concentration of diatoms coincide with the minima of bromine content, which can be explained by the influence of typhoons or other catastrophic events leading to floods and used later in paleoreconstructions.

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