Environmental effects on yellowfin tuna catch by the Taiwan longline fishery in the Arabian Sea

Lan, Kuo‐Wei; Lee, Ming-An; Nishida, Tom; Lu, Hang; Weng, Jinn-Shing; Chang, Yi

doi:10.1080/01431161.2012.685971

Cited by 12 publications

(11 citation statements)

References 26 publications

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“…Shifts in the distribution of catches and catch rates of yellowfin tuna by the purse seine fleet in the Indian Ocean have been associated with positive IOD events (Marsac and LeBlanc 2000;Menard et al 2007;Marsac 2008;Lan et al 2012a). During a positive IOD event in 1997-98, catch rates declined in the western Indian Ocean in association with a deepening of the thermocline and a reduction in surface biological productivity, which resulted in a reduction in surface schools available to the fishery.…”

Section: Introductionmentioning

confidence: 99%

Effects of climate variability on the distribution and fishing conditions of yellowfin tuna (Thunnus albacares) in the western Indian Ocean

2012

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Variations in the abundance and distribution of pelagic tuna populations have been associated with large-scale climate indices such as the Southern Oscillation Index in the Pacific Ocean and the North Atlantic Oscillation in the Atlantic Ocean. Similarly to the Pacific and Atlantic, variability in the distribution and catch rates of tuna species have also been observed in association with the Indian Ocean Dipole (IOD), a basin-scale pattern of sea surface and subsurface temperatures that affect climate in the Indian Ocean. The environmental processes associated with the IOD that drive variability in tuna populations, however, are largely unexplored. To better understand these processes, we investigated longline catch rates of yellowfin tuna and their distributions in the western Indian Ocean in relation to IOD events, sea surface water temperatures (SST) and estimates of net primary productivity (NPP). Catch per unit effort (CPUE) was observed to be negatively correlated to the IOD with a periodicity centred around 4 years. During positive IOD events, SSTs were relatively higher, NPP was lower, CPUE decreased and catch distributions were restricted to the northern and western margins of the western Indian Ocean. During negative IOD events, lower SSTs and higher NPP were associated with increasing CPUE, particularly in the Arabian Sea and seas surrounding Madagascar, and catches expanded into central regions of the western Indian Ocean. These findings provide preliminary insights into some of the key environmental features driving the distribution of yellowfin tuna in the western Indian Ocean and associated variability in fisheries catches.

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Section: Introductionmentioning

confidence: 99%

Effects of climate variability on the distribution and fishing conditions of yellowfin tuna (Thunnus albacares) in the western Indian Ocean

2012

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“…Although previous studies have identified relationships with the DMI (Corbineau et al ., ; Lan et al ., ,b), it was not retained in any of our models (Table ). This is not particularly surprising, as our study area did not overlap with the region from which the DMI values are calculated.…”

Section: Discussionmentioning

confidence: 99%

“…The Dipole Mode Index (DMI) is the gradient of SST anomalies across the western equatorial and the south eastern Indian Ocean. This gradient represents the intensity of the Indian Ocean Dipole (IOD; Saji et al ., ) and has been associated with fishing effort in the Indian Ocean (Corbineau et al ., ; Lan et al ., ,b).…”

Section: Methodsmentioning

confidence: 98%

Environmental associations with broad‐scale Japanese and Taiwanese pelagic longline effort in the southern Indian and Atlantic Oceans

Michael

Tuck

Strutton

et al. 2015

Fisheries Oceanography

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Tunas are globally important to fisheries because of their broad distribution and high market value. However, these characteristics also complicate their management, owing to difficulties estimating population size and sustainable harvest levels. Fishing effort data can be difficult to interpret, as the magnitude and distribution of effort are the result of multiple factors, including environmental variation and targeting different species. Yet, resolving patterns in fishing effort may provide information enabling the setting of sustainable harvest levels, the management of bycatch and the projection of potential responses to environmental change. To better understand the allocation of fishing effort, we evaluated Japanese and Taiwanese longline effort in the southern Indian and Atlantic Oceans and their relationships to the environment using generalized additive models. The variables evaluated included sea surface temperature (SST), sea ice extent, climate indices, and seasonal cycles, and the results were interpreted in physical, ecological, and management contexts. Our findings indicated hierarchical relationships are impacting fishing effort, with a seasonal cycle an important component of most models, which we hypothesize relates to variation in species targeting. This was often followed by finer‐scale environmental indices, including isotherms and sea ice, indicating region‐specific dynamics impacting the magnitude and distribution of fishing effort. Additionally, effort in some regions was associated with climate indices, highlighting interannual variation. This first quantitative description of the environmental associations of multi‐species tuna fleets in the Southern Ocean is a step towards an improved understanding of fleet behaviour.

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“…Monthly nominal catch rates were calculated as the number of fish captured per 1,000 hooks (fish/10 3 hooks). The number of hooks between floats was classified as regular (6–12 hooks) or deep (13–20 hooks; Lan et al., ; Lee et al., ). However, some logbook data did not contain this information, including all data from 1990 to 1994 and nearly 50% of the data from 1995 to 2002.…”

Section: Methodsmentioning

confidence: 99%

“…Monthly nominal catch rates were calculated as the number of fish captured per 1,000 hooks (fish/10 3 hooks). The number of hooks between floats was classified as regular (6-12 hooks) or deep (13-20 hooks; Lan et al, 2012;Lee et al, 2005).…”

Section: Bigeye Tuna Fishery Datamentioning

confidence: 99%

Association between the interannual variation in the oceanic environment and catch rates of bigeye tuna (Thunnus obesus) in the Atlantic Ocean

Lan

Lee

Chou

et al. 2018

Fisheries Oceanography

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The environmental processes associated with variability in the catch rates of bigeye tuna in the Atlantic Ocean are largely unexplored. This study used generalized additive models (GAMs) fitted to Taiwanese longline fishery data from 1990 to 2009 and investigated the association between environmental variables and catch rates to identify the processes influencing bigeye tuna distribution in the Atlantic Ocean. The present findings reveal that the year (temporal factor), latitude and longitude (spatial factors), and major regular longline target species of albacore catches are significant for the standardization of bigeye tuna catch rates in the Atlantic Ocean. The standardized catch rates and distribution of bigeye tuna were found to be related to environmental and climatic variation. The model selection processes showed that the selected GAMs explained 70% of the cumulative deviance in the entire Atlantic Ocean. Regarding environmental factors, the depth of the 20 degree isotherm (D20) substantially contributed to the explained deviance; other important factors were sea surface temperature (SST) and sea surface height deviation (SSHD). The potential fishing grounds were observed with SSTs of 22–28°C, a D20 shallower than 150 m and negative SSHDs in the Atlantic Ocean. The higher predicted catch rates were increased in the positive northern tropical Atlantic and negative North Atlantic Oscillation events with a higher SST and shallow D20, suggesting that climatic oscillations affect the population abundance and distribution of bigeye tuna.

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Environmental effects on yellowfin tuna catch by the Taiwan longline fishery in the Arabian Sea

Cited by 12 publications

References 26 publications

Effects of climate variability on the distribution and fishing conditions of yellowfin tuna (Thunnus albacares) in the western Indian Ocean

Effects of climate variability on the distribution and fishing conditions of yellowfin tuna (Thunnus albacares) in the western Indian Ocean

Environmental associations with broad‐scale Japanese and Taiwanese pelagic longline effort in the southern Indian and Atlantic Oceans

Association between the interannual variation in the oceanic environment and catch rates of bigeye tuna (Thunnus obesus) in the Atlantic Ocean

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