Development of habitat prediction models to reduce by-catch of sailfish (Istiophorus platypterus) within the purse-seine fishery in the eastern Pacific Ocean

2015 ◽  
Vol 66 (7) ◽  
pp. 644 ◽  
Author(s):  
Raul O. Martinez-Rincon ◽  
Sofia Ortega-Garcia ◽  
Juan G. Vaca-Rodriguez ◽  
Shane P. Griffiths

Sailfish (Istiophorus platypterus) is an important apex predator in neritic and oceanic pelagic ecosystems. The species is also a primary target of important catch-and-release sport fisheries that the support local economies of developing countries. However, commercial purse-seine fisheries that target tuna in the eastern Pacific Ocean (EPO) incidentally catch and discard large numbers of sailfish. Sailfish by-catch data recorded by scientific observers in the Mexican tuna purse-seine fleet in the EPO from 1998 to 2007 was used in generalised additive models (GAMs) to predict environmental and spatial preferences of sailfish. GAM predicted the highest sailfish catches to occur in coastal waters during El Niño events during late autumn and winter, with sea surface temperatures >26°C, with negative values of deviation in sea surface height (<–10cm), and low chlorophyll-a (<0.25mgm–3). GAM predicted that the catch probability for sailfish increased 1.8-fold during El Niño events in coastal waters and 1.5-fold under La Niña. However, the spatial distribution of sailfish remained largely unchanged during El Niño and La Niña events. Our models may be an additional fisheries management tool that may be used to support temporary spatial-temporal throughout the fishing season to reduce sailfish by-catch in the EPO.

Atmosphere ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 424
Author(s):  
Yinlan Chen ◽  
Li Yan ◽  
Gen Li ◽  
Jianjun Xu ◽  
Jingchao Long ◽  
...  

In the recent four decades, there were three record-breaking El Niño events: 1982/1983, 1997/1998, and 2015/2016 events. A double intertropical convergence zone (ITCZ) pattern distinctively emerges over the eastern Pacific Ocean during boreal spring. Based on reanalysis (ERA-Interim) during 1979–2018, this study examines how these three extreme El Niños modulate such double ITCZs. The 1982/1983 and 1997/1998 El Niños moved both northern and southern ITCZs equatorward to form an individual and broad equatorial ITCZ. In contrast, the regulation of 2015/2016 El Niño was unique with a strengthened southern ITCZ to form a symmetric double-ITCZ. The above differences can be attributed to the different meridional structures of sea surface temperatures (SSTs). For the 1982/1983 and 1997/1998 El Niños, there was a meridionally symmetric structure of SST warming with a maximum at the equator. While for 2015/2016 El Niño, there was a meridionally symmetric structure of SST warming with a minimum at the equator.


Eos ◽  
2016 ◽  
Vol 97 ◽  
Author(s):  
Sarah Stanley

Underwater gliders and ocean modeling reveal unexpectedly weak El Niño effects on a major West Coast current.


2021 ◽  
Vol 241 ◽  
pp. 106001
Author(s):  
Osman Crespo-Neto ◽  
Eric Díaz-Delgado ◽  
Tatiana A. Acosta-Pachón ◽  
Raúl O. Martínez-Rincón

2012 ◽  
pp. n/a-n/a
Author(s):  
Cleridy E. Lennert-Cody ◽  
Jeremy D. Rusin ◽  
Mark N. Maunder ◽  
Edward H. Everett ◽  
Erick D. Largacha Delgado ◽  
...  

2019 ◽  
Vol 169-170 ◽  
pp. 104621 ◽  
Author(s):  
Chin-Hwa Sun (Jenny) ◽  
Mark N. Maunder ◽  
Minling Pan ◽  
Alexandre Aires-da-Silva ◽  
William H. Bayliff ◽  
...  

2008 ◽  
Vol 65 (6) ◽  
pp. 970-978 ◽  
Author(s):  
Cleridy E. Lennert-Cody ◽  
Jason J. Roberts ◽  
Richard J. Stephenson

Abstract Lennert-Cody, C. E., Roberts, J. J., and Stephenson, R. J. 2008. Effects of gear characteristics on the presence of bigeye tuna (Thunnus obesus) in the catches of the purse-seine fishery of the eastern Pacific Ocean. – ICES Journal of Marine Science, 65: 970–978. Overfishing of bigeye tuna in the eastern Pacific Ocean has motivated a search for a practical means of reducing the catch of bigeye tuna in mixed species aggregations. To explore the effects of gear characteristics on the catch of bigeye tuna, a classification algorithm for the presence/absence of bigeye tuna catch in purse-seine sets on floating objects is developed, using the tree-based method, random forests. Although the location of the set was the strongest determinant of bigeye tuna catch with these data, bigeye tuna in some areas were more likely to be caught on floating objects with greater underwater depths and with deeper purse-seines. Misclassified sets that caught bigeye tuna were concentrated within certain vessels, suggesting the existence of additional vessel effects. Results indicate that fishers may avoid catching bigeye tuna in some areas by changing the depth of the material hanging from the floating object and the actual fishing depth of the purse-seine, or by moving to other fishing areas. Nonetheless, given the complexity of configuring a purse-seine, and the difficulties associated with monitoring compliance with gear regulations, fishery-wide gear restrictions would be problematic.


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