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Developing an Abundance Index of Skipjack Tuna (Katsuwonus pelamis) from a Coastal Drifting Gillnet Fishery in the Southern Waters of Indonesia

1
Marine Research Center, Jakarta 14430, Indonesia
2
Department Fishing Technology, Faculty Fishing Technology, Fisheries University Jakarta, Jakarta 12520, Indonesia
3
Research Institute for Tuna Fisheries, Bali 80224, Indonesia
*
Author to whom correspondence should be addressed.
These authors contributed equally to this work.
Fishes 2019, 4(1), 10; https://doi.org/10.3390/fishes4010010
Received: 10 December 2018 / Revised: 18 January 2019 / Accepted: 18 January 2019 / Published: 11 February 2019
Skipjack tuna is targeted by various types of fishing gear in coastal countries. Due to its resilience, it has withstood heavy fishing pressure in the past few decades. Coastal drifting gillnet fleets also mark skipjack as their main target, but it is often overlooked in terms of stock assessment. This study provides new information on an abundance index based on fishery-dependent data from 2010 to 2017. Generalized linear models (GLMs) were used to standardize the catch-per-unit-of-effort (CPUE) using year, quarter, and gross tonnage as the prediction variables. Model goodness-of-fit and model selection were based on the Akaike Information Criterion (AIC), the pseudo coefficient of determination (R2), and model diagnostics with a residual analysis. The final estimation of the abundance index was calculated by least square means or marginal means. The results showed that the index was heavily influenced by the year and quarter, but it did not relate to the vessel’s capacity. While the CPUE series fluctuated greatly, it showed a declining trend over the years of observation. View Full-Text
Keywords: abundance index; small scale; drifting gillnet; generalized linear model; Indian Ocean abundance index; small scale; drifting gillnet; generalized linear model; Indian Ocean
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Novianto, D.; Ilham; Nainggolan, C.; Syamsuddin, S.; Efendi, A.; Halim, S.; Krisnafi, Y.; Handri, M.; Basith, A.; Yusrizal; Nugraha, E.; Nugroho, S.C.; Setyadji, B. Developing an Abundance Index of Skipjack Tuna (Katsuwonus pelamis) from a Coastal Drifting Gillnet Fishery in the Southern Waters of Indonesia. Fishes 2019, 4, 10.

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