Abandoned, Lost or Otherwise Discarded Fishing Gear (ALDFG) in Tuna Pole-and-Line Fisheries

The fishing industry is recognized as one of the primary sources of at-sea marine litter, largely through its contributions via abandoned, lost or otherwise discarded fishing gear (ALDFG). Individual fleet’s contributions to ALDFG vary significantly across this global industry. While much information is available for some fisheries, the rate of ALDFG remains poorly known for many techniques. In this study, we used data collected by fisheries observers onboard pole-and-line fishing vessels in the Azores (Atlantic Ocean) and the Maldives (Indian Ocean) to provide an accurate and representative estimate of ALDFG for this gear. Our analysis of 993 fishing events demonstrated ALDFG contributions much lower than have been recorded for any other commercial tuna fishing gear. Overall, we found that an angler loses some monofilament line in 1.4% (±0.2) of fishing events. This informs that for every thousand tonnes of tuna harvested using this fishing technique, 0.3 kg of nylon is entering the marine environment. Globally, we estimate that all pole-and-line fisheries together contribute to 96 kg ± 42.6 kg of ALDFG per year. These results further evidence the low environmental impact of this traditional fishing practice, as well as the need for other methods to convert to less damaging gears.

A non-negative matrix factorization based clustering to identify potential tuna fishing zones

<span lang="EN-US">Many nonnegative matrix factorization based clusterings are employed in discovering pattern and knowledge. Considering the sparseness nature of our data set about the daily tuna fishing data, we attempted to utilize a clustering approach, which is based on non-negative matrix factorization. Adding sparseness constraint and assigning good initial value in the modified NMF method, a proposed algorithm Direct-NMFSC yielded better result cluster compared to other methods which are also utilizing sparse constraint to their approaches, SNMF and NMFSC. The result of this study shows that Direct-NMFSC has 5.376 times of iteration number less than NMFSC in average with 531.97 as the CH index result. The determination of potential fishing zones is one of the essential efforts in the potential fishing zone mapping system for tuna fishing. By means of this novel data-driven study to construct the information and to identify the potential tuna fishing zones is done. We also showed that utilizing the Direct-NMFSC can spot and identify the potential tuna fishing zones presented in red cluster that covers both the spatial and temporal information.</span>

DINAMIKA MUSIM PENANGKAPAN IKAN CAKALANG DAN TONGKOL DI PERAIRAN PALABUHANRATU

The monthly fluctuation of fish catch is closely related to the presence of fish or the fishing season. Information about the fishing season is important to improve the efficiency and effectiveness of fishing carried out by fishermen. Skipjack and tuna are important catches landed by fishermen in Palabuhanratu fishing port, with fishing grounds in the waters around Palabuhanratu Bay. This study aims to describe the dynamics of the catch and the effort to catch skipjack and tuna that land their fish in the Palabuhanratu fishing port and determine the fishing season. The data used is the Palabuhanratu fishing port fisheries statistical data for the 2015-2019 period. Data analysis used catch per unit effort (CPUE) analysis and moving average model. The results showed that the CPUE value of skipjack tuna fluctuates tends to increase by 0,009 tons per trip and reaches the highest in 2017 which is around 3,068 tons per trip. The CPUE value of tuna tends to increase from 0,021 tons per trip in 2015 to 0,266 tons per trip in 2019. The skipjack tuna fishing season occurs in March, July to November, while the tuna fishing season occurs from July to November. Keywords: skipjack tuna, fishing season index, moving average model, tongkol, Palabuhanratu

Tuna Fisheries Conservation and Management in the Pacific Islands Region

The Korean tuna fishing fleet has a long history of participation in the tuna fisheries of the Western and Central Pacific Ocean (wcpo), the largest tuna fisheries in the world. As one of the largest distant water fishing fleets operating in the wcpo, Korea has a strong interest in maintaining access to both eez s and the high seas, and ensuring sustainability of the region’s tuna stocks. The regulatory environment for tuna fisheries in the wcpo is complex and multi-layered, with regional, sub-regional and national legislation, regulation and policies all affecting tuna fishing vessels and operations. Management of tuna fisheries within Pacific Island eez s is increasingly being tightened, including through the introduction of zone-based management approaches, and Pacific Island countries are also advocating for improved management of tuna fishing in the high seas. While all four primary tuna species in the wcpo are currently considered healthy, catch rates and economic conditions in the southern and tropical longline fisheries are in decline and catch reductions will be necessary to improve catch rates and increase economic returns for longline vessels. Within this context, the Korean distant water fishing fleet will need to strengthen engagement and cooperation with Pacific island States in order to maintain their competitiveness.

Analysis of sizes and state of ovarian maturity in yellowfin tuna (Thunnus albacares) captured in the Gulf of Mexico

The yellowfin tuna Thunnus albacares is the second most important fishery in Mexico, due to its production costs and commercial value” The species is fished on both coast of the country, with the Pacific Ocean presenting productions lightly higher than that of the Gulf of Mexico where, in spite of the above statement, tuna catches have recently shown a downward trend. For this reason, analysis is required of the size and stage of ovarian maturity and it is necessary to determine whether capture size is the primary reason behind the decline in the yellowfin tuna fishery Three tuna fishing trips were conducted in the Gulf of Mexico in order to gather data pertaining to fork length (Lf) and gonads Histological sections were obtained from the latter for analysis and determination of maturity stage. The results showed that males were predominant (40%) among the individuals for which the sex could be differentiated in the catches of T. albacares. The Lf values in the catch, were between 75 and 162 cm. However, variations in this parameter were found between sexes. The relationship between length and weight showed that the males are larger than the females, however, the equationgiven by the parameters of a=0.9406 and b= 3.4504, demonstrated growth of positive allometric type in both sexes. There was progressive development in the state of ovarian maturity over the months of capture. Chromatin nuclear (CN) was the most frequent phase within primary ovarian development (November, February, March), stages were present, although these did not present a direct relationship to fork length.

Analisis Pendapatan Usaha Nelayan Tangkap Ikan TunaDi Kabupaten Manokwari

The purpose of his study aims to determine and analyze how much the income level of tuna fishing business is and what factors affect the level of tuna fishing business income in Manokwari Regency. The analytical method used is the quantitative descriptive analysis method with interview guides and questionnaires as instruments. Data analysis was performed using multiple linear regression analysis. The results showed that simultaneously and partially the variables of capital, length of time at sea, number of workers and experience at sea had a significant effect on the income of tuna fishermen in Manokwari Regency.

Karakteristik Pola Pertumbuhan dan Distribusi Ukuran Thunnus albacares, Bonnaterre, 1788 (Teleostei: Scombridae) yang Tertangkap dengan Pancing Ulur di Perairan Selatan Pulau Ambon

Handline is a fishing tool that is always used by fishermen in Passo Village to catch tuna fish in the southern waters of Ambon Island. In carrying out tuna fishing activities, these fishermen use two hand lines at the same time operating together but differ in their operating techniques. This research was conducted to know the size distribution and growth pattern of yellowfin tuna caught by handline (PUT and PUH) in the southern waters of Ambon Island. From the results of this study, the total yellowfin tuna caught using the PUT handline was 323 individuals with an average class length of 117.23 cm, while the yellowfin tuna caught using the PUH handline was 159 with an average class length of 118.1 cm. The average total weight of yellowfin tuna caught by the PUT handline was 21.26 kg. The average total weight caught using the PUH handline was 21.94 kg. The growth pattern of yellowfin tuna as a whole is negative allometric, which means that the length growth is faster than the weight growth. Pancing ulur merupakan alat tangkap yang selalu dipakai oleh nelayan di Desa Passo untuk menangkap ikan tuna di perairan selatan Pulau Ambon. Dalam melakukan aktivitas penangkapan ikan tuna, nelayan tersebut menggunakan dua pancing ulur (hand line) sekaligus diopresikan secara bersama-sama namun berbeda dalam teknik pengoprasiannya. Penelitian ini dilakukan dengan tujuan untuk mengetahui distribusi ukuran dan pola pertumbuhan ikan tuna madidihang yang tertangkap dengan pancing ulur (PUT dan PUH) di perairan selatan Pulau Ambon. Dari hasil penelitian ini total ikan tuna madidihang yang tertangkap dengan PUT sebanyak 323 individu dengan rata-rata kelas ukuran panjang yang tertangkap yaitu 117.23 cm, sedangkan tuna madidihang yang tertangkap menggunakan PUH sebanyak 159 ekor dengan rata-rata kelas ukuran panjang 118.1 cm. Rata-rata berat total tuna madidihang yang tertangkap dengan PUT yaitu 21.26 kg. rata-rata berat total yang tertangkap dengan PUH yaitu 21.94 kg. Pola pertumbuhan ikan tuna madidihang secara keseluruhan bersifat allometrik negatif hal ini berarti pertumbuhan panjang lebih cepat pertumbuhan beratnya.